Growth and development (physiology of)  - Cattle

Strydom, P. E.; Frylinck, L.; van der Westhuizen, J.; Burrow, H. M. 2008 Growth performance, feed efficiency and carcass and meat quality of tropically adapted breed types from different farming systems in South Africa. Australian Journal of Experimental Agriculture, 48(5): 599–607


Keywords: Growth performance, feed efficiency, carcass, meat quality, farming systems, beef cattle, South Africa


Short summary: Two experiments measured the ability of tropically adapted beef breeds from resource-poor farmer herds in South Africa to produce high quality beef under commercial feedlot conditions. The resource-poor farming sector consists of ‘emerging’ and communal farmers. The herd and breed groups consisted of Sanga types (tropically adapted Bos taurus breed) including Nguni, Tuli, Bonsmara and Drakensberger, as well as Brahman and non-descript groups. The cattle were slaughtered after an average of 97 days in the first experiment and after an average of 92, 140 and 169 days on a grain-based diet in the second experiment. Growth performance, carcass quality and yield, occurrence of disease and meat quality were measured.

The performance of the breeds groups was a function of their genetic potential and herd type (carcass weight and condition at arrival). Steers from emerging and communal farmer herds enter the feedlot at a lighter weight, but show similar growth performance to achieve acceptable, albeit lighter carcass weights, than their commercial counterparts. The incidence of disease was no different between commercial, emerging and communal herds. Carcass and meat quality analyses indicate small or no differences between herd types or breeds, except that Brahman produced tougher meat.


Innovative concept: It was concluded that cattle from resource-poor farmer herds have the ability to meet the specifications of South Africa’s commercial beef markets, indicating a genuine opportunity for import substitution.


Siddiqui, M.A.R., Bhattacharjee, J., Das, Z.C., Islam, M.M., Islam, M.A., Haque, M.A., Parrish, J.J., Shamsuddin, M. 2008 Crossbred Bull Selection for Bigger Scrotum and Shorter Age at Puberty with Potentials for Better Quality Semen. Reproduction in Domestic Animals, 43, 74–79


Keywords: Crossbreeding, bull, puberty, reproductive traits


Short summary: Obtaining semen at the earliest possible age from bulls being proven tested is desirable to hasten the identication of superior sires. Shortening age at puberty of crossbred breeding bull is an important issue in cattle breeding, especially in the tropic. Early puberty in bulls is positively related to early puberty and subsequent pregnancy rates in their o-spring. The present study of Siddiqui et al. was aimed at determining the earliest possible age at which crossbred bulls with larger scrotal circumference would attain puberty with potentials for the production of quality semen for articial breeding. One hundred and thirty one crossbred bulls were examined. The bulls were of crossbred where the dam was either indigenous nondescript zebu or Sahiwal or crosses of nondescript zebu with Sahiwal and the sire was Holstein-Friesian. Results from this study conrmed that the larger scrotum has positive effect on proportion of spermatozoa with normal morphology. Therefore, if selection is made based on the guideline of this study, the crossbred bulls in tropics will produce better quality semen at an earlier age. An interesting nding of the present study is that the bull with a thicker scrotal skin produced a higher proportion of head abnormal spermatozoa.


Innovative concept: Cluster analysis of data on age at rst ejaculate collection and other reproductive traits of young bulls resulted in selection of 29.6% bulls with uniform and reduced age at puberty and increased scrotal circumference.



Strydom, P. E., Frylinck, L., van der Westhuizen, J., Burrow, H. M. 2008 Growth performance, feed efficiency and carcass and meat quality of tropically adapted breed types from different farming systems in South Africa. Australian Journal of Experimental Agriculture, 48(5): 599–607


Keywords: Growth performance, feed efficiency, carcass, meat quality, farming system, beef cattle, South Africa


Short summary: Two experiments measured the ability of tropically adapted beef breeds from resource-poor farmer herds in South Africa to produce high quality beef under commercial feedlot conditions. The herd and breed groups consisted of Nguni, Tuli, Bonsmara and Drakensberger, as well as Brahman and non-descript groups. The cattle were slaughtered after an average of 97 days in the first experiment and after an average of 92, 140 and 169 days on a grain-based diet in the second experiment. Growth performance, carcass quality and yield, occurrence of disease and meat quality were measured. The performance of the breeds groups was a function of their genetic potential and herd type (carcass weight and condition at arrival). Steers from emerging and communal farmer herds enter the feedlot at a lighter weight, but show similar growth performance to achieve acceptable, albeit lighter carcass weights, than their commercial counterparts. The incidence of disease did not differ between commercial, emerging and communal herds. Carcass and meat quality analyses indicate small or no differences between herd types or breeds, except that Brahman produced tougher meat.


Innovative concept: Cattle from resource-poor farmer herds have the ability to meet the specifications of South Africa’s commercial beef markets, indicating a genuine opportunity for import substitution.


Shirley, K. L., Beckman D. W., Garrick, D. J. 2008 Inheritance of pulmonary arterial pressure in Angus cattle and its correlation with growth. Journal of Animal Science, 86: 815-819


Keywords: Cattle, growth, heritability, maternal effect, pulmonary arterial pressure


Short summary: (Co)-variancecomponents for PAP, birth weight, and adjusted 205-d weaningweight were estimated from 2,305 spring-born, registered Anguscattle A singlemeasure of PAP was collected after weaning on animals born from1984 to 2003. Multitrait animal models with and without PAP maternaleffects were fitted. The interaction of year x sex was a significant fixed effectfor PAP, but age of dam was not. Age at PAP testingwas a significant linear covariate for PAP, andscores increased 0.012 ± 0.007 mmHg·dof age. Heritability of PAP direct was 0.34 ± 0.05. Maternalheritability converged to a boundary at 0.0, and the model withmaternal genetic effects for PAP was not significantly betterthan a model with only direct effects. Phenotypically, PAP wasuncorrelated with birth or weaning weights. Genetically, PAPappeared to have positive, unfavorable relationships with directeffects for birth (0.49 ± 0.12) and weaning weight (0.50± 0.18). Positive correlations imply sires whose offspringexhibited resistance to brisket disease had lower weights andgains. A model that evaluated PAP in females and males as differenttraits had heritability estimates for each sex of 0.38 ±0.07 and 0.46 ± 0.09, respectively, with a genetic correlationof 0.64 ± 0.12 between the sexes and was not significantlybetter than the model assuming homogeneity by sex and a unitgenetic correlation between sexes.


Innovative concept: The results suggest thatPAP is moderately heritable in spring-born Angus cattle acclimatizedand tested at high altitude, and selection for low PAP scoreswould be effective.


Annen, E. L., Stiening, C. M., Crooker, B. A., Fitzgerald, A. C. Collier, R. J. 2008 Effect of continuous milking and prostaglandin E2 on milk production and mammary epithelial cell turnover, ultrastructure, and gene expression. Journal of Animal Science, 86:1132-1144.


Keywords: Apoptosis, dairy cow, dry period, mammary epithelial cell, proliferation, prostaglandin


Short summary: The objectives were to 1) compareMEC turnover, ultrastructure, and gene expression in CM andinvoluting mammary tissue, and 2) evaluate the effects of CMand intramammary infusion of PGE2 on early lactation MEC turnover,ultrastructure, mammary gene expression, milk yield, and composition.First- and second-lactation cows were used in a half-uddermodel, in which one-half was dry for 60 d (CTL) and the otherwas CM. Udder halves were assigned to a postpartum(PP) treatment of PGE2 (+PGE2; 875 µg/10 mL of medium-chaintriglyceride oil) or no PGE2 (–PGE2) treatment at parturitionand at 72 h PP. Biopsies of CM and CTL quarters were obtainedduring milk stasis (MS) of the CTL half at 3 and 7 d after dry-offof the CTL half (3d-MS; 7d-MS) and postpartum (PP) at 2 and4 d (2d-PP; 4d-PP). Milk yield was reduced (P < 0.01) inCM udder halves compared with CTL halves (13.2 vs. 22.1 kg/d),but reductions were less in second-lactation cows. The apoptoticindex was greater (P < 0.05) in CTL glands than in CM glands(3d-MS, 0.52 vs. 0.11% and 7d-MS, 0.24 vs. 0.12, respectively).Proliferation of MEC was unchanged at 3d-MS, but was increased(P = 0.01) in CTL halves at 7d-MS compared with CM halves (3.10vs. 0.93%). At 2d-PP, MEC proliferation was increased (P = 0.05)in CM halves compared with CTL halves (1.3 vs. 0.6%), but wasunaffected by PGE2 (P > 0.2). Apoptosis was elevated in earlylactation regardless of treatment. Ultrastructure was unchangedby dry period length or PGE2.


Innovative concept: The results confirm that CM reduced milk yield of cows witha mammary growth requirement.


Wathes, D.C.; Cheng, Z.; Bourne, N.; Taylor, V.J.; Coffey, M.P.; Brotherstone, S. 2007 Differences between primiparous and multiparous dairy cows in the inter-relationships between metabolic traits, milk yield and body condition score in the periparturient period. Domestic Animal Endocrinology, 33, 203–225


Keywords: Dairy cow; parity; IGF-I; insulin; milk yield; body condition score


Short summary: Over the past decades, the Holstein breed has been selected to produce high yields through a greater propensity for losing body condition to support milk production in early lactation and to target nutrients preferentially to the mammary gland. The late dry period coincides with the last phase of fetal growth, so the nutrient requirements for the gravid uterus increase, and within 4 days of calving a further dramatic rise in the demand for glucose, amino acids and fatty acids for milk synthesis occurs. This is associated with alterations in blood metabolite and hormone profiles which in turn influence milk yield and fertility. The aims of research were: (1) to use a modelling approach to determine how metabolic traits, milk yield and body condition score were inter-related at different times in the periparturient period and (2) to compare these relationships in primiparous and multiparous cows. Obtained results suggest that there are differences in the control of tissue mobilization between primiparous and multiparous cows which may promote nutrient partitioning into growth as well as milk during the first lactation. Results aslo suggest that the differing endocrine background in the less mature animals may limit partitioning of nutrients into milk.


Innovative concept: This study developed models to determine how metabolic traits, milk yield and BCS were inter-related at different times in the periparturient period and to compare these relationships in primiparous and multiparous cows.


Kasai Kouji, Sano Fumihiko, Miyashita Norikazu, Watanabe Shinya, Nagai Takashi 2007 Comparison of the Growth Performances of Offspring Produced by a Pair of Cloned Cattle and Their Nuclear Donor Animals. Journal of Reproduction and Development, Vol. 53, No. 1, 2007


Keywords: Cattle, Calf of clones, Full siblings, Growth performance, Somatic cell cloning


Short summary: According to authors, there are a number of potential advantages that come from the use of cloned livestock such as making genetic copies of elite seed stock and preservation of endangered breeds. However, many studies that have investigated the link between errors in epigenetic modification shown that cloned embryos have epigenetic errors that cause loss of embryos and fetuses during differentiation and development in the uterus. Kasai et al. carried out this study in order to compare the growth performance of offspring obtained by mating a pair of cloned cattle with that of full siblings produced by mating the nuclear donors of the cloned animals. Results from this research show that the mating of a cloned dam and sire of the Japanese Black breed produced a calf whose birth weight was within the normal rage for Japanese Black breed cows. These observations would suggest that large offspring syndrome was not a problem among the progeny of pairs of clones in these studies. Also, the present study shows that the growth curves for body weight and shoulder height of the calf of clones were within the range of its full siblings produced by crossing the animals used as nuclear donors.


Innovative concept: Results support the premise that progeny produced by mating clones could be expected to have the same phenotypes as those of full siblings produced by mating the animals used as nuclear donors.


Oka Akio, Iwaki Fumiyuki, Iwamoto Eiji, Tatsuda Ken 2007 Effects of growth rate during the early fattening period on growth, carcass characteristics and circulating hormones in the different growth hormone genotypes of Japanese black steers. Animal Science Journal (2007) 78, 142–150


Keywords: Carcass characteristics, circulating hormones, GH genotype, growth rate,


Short summary: Growth hormone is well known to facilitate growth of animals and the meat quality of fattening cattle. Since the Japanese Black cattle have large variations in growth rate and meat quality, it is important to determine if the growth hormone genetic variants might be associated with those variations. In the present study, authors determined the growth rate, the beef quality and the circulating hormone levels in two strains (A (Leucine) and B (Valine) at amino acid position 127 of the protein) of Japanese Black steers, and evaluated the effect of high and moderate growth rates during early fattening period on growth and beef quality. The findings suggest that cattle with genotype A have greater feed intake, body weight and carcass weight than those of genotype B. Moreover, the steer with genotype A had higher percentages of 14:1 and 16:1 acids, and lower percentage of 18:0 in intramuscular lipid than the steers with genotype B. It should be noted that fatty acid composition of carcass fat might be affected by GH genotype. The present results also suggest that Japanese Black steers with genotype A have higher plasma GH concentration and lower serum IGF-I concentration than those with genotype B.


Innovative concept: The results of this study suggest that differences in growth and carcass characteristics of Japanese Black steers might be affected by differences in growth hormone status.


Brito, Leonardo F.C.; Barth, Albert D.; Rawlings, Norm C.; Wilde, Randal E.; Crews Jr, Denny H.; Mir, Priya S.; Kastelic, John P. 2007 Effect of improved nutrition during calfhood on serum metabolic hormones, gonadotropins, and testosterone concentrations, and on testicular development in bulls. Domestic Animal Endocrinology, 33, 460–469


Keywords: Bull; nutrition; metabolic hormones; puberty; testes


Short summary: Identification of hormonal links between nutritional status and the metabolic sensor is essential for elucidation of the mechanisms by which nutrition affects both growth and reproduction. Differences in mature testes weight in the absence of differences in metabolic hormones concentrations during the peripubertal period in bulls receiving different nutrition suggested that the gonadotropin-independent mechanisms involved in testicular growth are dependent on previous exposure to gonadotropins during calfhood. Therefore, increased gonadotropin secretion promoted by improved nutrition during calfhood may positively affect mature testes size in bulls. The objective of the present study was to evaluate the effects of improved nutrition during calfhood on serum metabolic hormones, gonadotropins and testosterone concentrations, and on sexual development in bulls. Obtained results suggest that improved nutrition during calfhood hastened body development and testosterone secretion, and increased testicular weight and sperm production at 74 weeks of age. Improved nutrition resulted in increased testosterone secretion that was associated with greater circulating IGF-I concentrations, suggesting a role for this metabolic hormone in regulating Leydig cell number and function. The beneficial effects of improved nutrition on testicular development extended beyond calfhood, but were probably related to the increased LH secretion during calfhood.


Innovative concept: Improved nutrition during calfhood resulted in greater testicular weight and sperm production in mature bulls, indicating that a more prolonged LH pulse frequency during calfhood, and increased IGFI and testosterone concentrations during calfhood and peripubertal period were associated with greater testicular cell proliferation and enhanced function.


Masoudi, A.A, Uchida, K., Yokouchi, K., Miyadera, K., Ogawa, H., Sugimoto, Y., Kunieda, T. 2007 Marker-assisted selection for forelimb-girdle muscular anomaly of Japanese Black cattle. Animal Science Journal, 78 (6): 672–675


Keywords: Marker-assisted selection, forelimb-girdle muscular anomaly, Japanese Black cattle


Short summary: Forelimb-girdle muscular anomaly is a hereditary disorder of Japanese Black cattle characterized by tremors and astasia caused by hypoplasia of the forelimb-girdle muscles. The locus responsible for this disorder has been mapped on a middle region of bovine chromosome 26. In this study, marker-assisted selection was applied to identify the carriers of this disorder. Four microsatellite markers, DIK4440, BM4505, MOK2602 and IDVGA-59, linked to the disorder locus were genotyped in 37 unaffected offspring of a carrier sire. Transmission of the mutant or wild-type allele of the disorder locus of the sire to the 37 offspring was determined by examining the haplotypes of these markers. The results showed that nine and 18 of the 37 animals possessed the paternally transmitted mutant and wild-type alleles, respectively, and therefore, the nine animals with the mutant allele were identified as carriers.


Innovative concept: Marker-assisted selection using these four markers can be applied for the identification of the carriers of forelimb-girdle muscular anomaly of Japanese Black cattle.


Nkrumah, J. D., Sherman, E. L., Li, C., Marques, E., Crews, Jr., D. H., Bartusiak, R., Murdoch, B., Wang, Z., Basarab, J. A., Moore, S. S. 2007 Primary genome scan to identify putative quantitative trait loci for feedlot growth rate, feed intake, and feed efficiency of beef cattle. Journal of Animal Science, 85:3170-3181.


Short summary: The study was conducted to identify QTL for feed intake and feed efficiency of beef cattle by using genotype information from 100 microsatellite markers and 355 SNP genotyped across 400 progeny of 20 Angus, Charolais, or Alberta Hybrid bulls. Traits analyzed include feedlot ADG, daily DMI, feed-to-gain ratio [F:G, which is the reciprocal of the efficiency of gain (G:F)], and residual feed intake (RFI). A mixed model with sire as random and QTL effects as fixed was used. Putative QTLs for ADG were detected across families on chromosomes 5. For DMI, putative QTLs were detected on chromosomes 1. Putative across-family QTLs influencing F:G were detected on chromosomes 3, 5, 7, 11, 16, 17, 22, 24, and 28. Putative QTLs influencing RFI were detected on chromosomes 1, 5, 7, 8, 12, 16, 17, and 26 in the across-family analyses. In addition, a total of 4, 6, 1, and 8 chromosomes showed suggestive evidence (chromosome-wise, P < 0.10) for putative ADG, DMI, F:G, and RFI QTL, respectively. Most of the QTL detected across families were also detected within families, although the locations across families were not necessarily the locations within families, which is likely because of differences among families in marker informativeness for the different linkage groups.


Innovative concept: The locations and direction of some of the QTL effects reported in this study suggest potentially favorable pleiotropic effects for the underlying genes. Further studies will be required to confirm these QTL in other populations.


Echternkamp, S. E. Thallman, R. M. Cushman, R. A. Allan, M. F. Gregory, K. E. 2007 Increased calf production in cattle selected for twin ovulations. Journal of Animal Science, 85:3239-3248.


Keywords: calf birth and weaning weight, cattle, fetal development, sex ratio, survival, twins


Short summary: The effects of increasing fetal numbers and their distribution between the left and right uterine horns on calf survival, calf BW at birth and weaning, gestation length, dystocia, and calf sex ratio were evaluated for single, twin, and triplet calves born to primiparous and multiparous females. Cattle were distributed equally between the spring and fall breeding seasons. For cows and heifers combined, number of calves per parturition increased from 1.34 in 1994 to 1.56 in 2004. Gestation length was 6.8 d shorter for twins compared with singles and 12.7 d shorter for triplets. Survival and BW of individual calves at birth decreased, but total calf BW per dam increased as fetal number increased from single to triplet births. Twins resulting from bilateral twin ovulations had increased survival and BW at birth, a longer gestation length, and less dystocia than twins resulting from unilateral twin ovulations. Birth weight of single calves increased by 0.51 kg/d for each additional day of gestation length vs. 0.38 kg/d for individual twins. Calf BW at birth increased with age of dam from 2 to 4 yr. Twin and triplet births had a greater incidence of dystocia than single births. The ratio of male:female calves at birth was not affected by type of birth. Postnatal calf survival was similar for all 3 types of birth.


Innovative concept: Although most bovine females have the uterine capacity to gestate twin calves, decreased survival and BW of unilateral twins and of all triplets indicate that their growth and development may have been compromised by uterine crowding.


Swali, A., Wathes, D.C. 2007 Influence of primiparity on size at birth, growth, the somatotrophic axis and fertility in dairy heifers. Animal Reproduction Science, 102 (1-2): 122-136


Keywords: Cattle-heifers; Parity; Fertility; Somatotrophic axis; Growth


Short summary: This study compared birth size, growth rates and fertility in consecutively born heifer offspring of 45 primiparous (PP) and 71 multiparous (MP) dairy cows on one farm. Measures of the somatotrophic axis (GH, insulin, IGF-I and glucose) were compared in blood samples collected at the start of the first lactation. Offspring of PP cows were significantly smaller at birth (weight, length, height, girth, P < 0.01) than those born to MP dams. The ponderal index (weight/height3) was similar, showing that growth restriction was proportional. These differences were no longer apparent at 3 months, indicative of early catch up growth. The PP offspring conceived more rapidly during their first service period as nulliparous heifers (P < 0.02). They experienced a greater weight loss postpartum (P < 0.002) and had lower concentrations of IGF-I and insulin following their first calving (P < 0.05). Fertility in the first lactation was, however, similar between the two groups.


Innovative concept: It is concluded that having a primiparous dam resulted in a smaller size at birth and influenced the somatotrophic axis around calving. Fertility was generally better in offspring of PP than MP dams.



Lusk, J. L. 2007 Association of single nucleotide polymorphisms in the leptin gene with body weight and backfat growth curve parameters for beef cattle. Journal of Animal Science, 85:1865-1872.


Keywords: Backfat, beef cattle, growth curve, leptin gene, single nucleotide polymorphism


Short summary: The objective of this study was to investigate the effect of 2 leptin SNP on growth curve parameters for BW and backfat. Two SNP (UASMS2 and R25C) were genotyped on 1,653 cross-bred steers and heifers in a commercial feedlot. Up to 4 serial measures of BW and ultrasound estimates of backfat thickness were taken for each animal from the time of placement on feed to slaughter. The measures were used to estimate growth models that describe changes in BW and backfat thickness as a function of days on feed. Data analysis was carried out by estimating nonlinear mixed models to determine the individual and joint effect of each SNP on growth curve parameters. Brody growth curves were fit to the BW data. Variations in the R25C SNP did not significantly affect growth parameters individually or in combination with the UASMS2 SNP. Variations in the UASMS2 SNP were significant in Brody growth curve parameters for BW growth (P < 0.001). The genotype UASMS2-CC was the heaviest at the beginning of the feeding period and exhibited the largest asymptotic mature BW, but UASMS2-TT cattle exhibited the fastest rate of BW growth. A modified power function was fit to the serial ultrasound backfat measures. Models that included the combined effect of the R25C and UASMS2 SNP provided the best fit to the data. Genotypes differed significantly in power function parameters for backfat growth (P < 0.001). The R25C-CC/UASMS2-TT cattle had the smallest backfat thickness at placement. The genotype R25C-CC/UASMS2-TT exhibited the fastest backfat growth rate, whereas backfat in R25C-CC/UASMS2-CC cattle grew at the slowest rate.


Innovative concept: The association between leptin genotype and growth in BW and backfat presents opportunities to identify genetically distinct cattle and to differentially optimize feeding times accordingly.


Nkrumah, J. D., Keisler, D. H., Crews, Jr., D. H., Basarab, J. A., Wang, Z., Li, C., Price, M. A., Okine, E. K., Moore, S. S. 2007 Genetic and phenotypic relationships of serum leptin concentration with performance, efficiency of gain, and carcass merit of feedlot cattle. Journal of Animal Science, 85:2147-2155.



Keywords: beef cattle, carcass merit, feed efficiency, performance, serum leptin


Short summary: This study estimated the genetic variation in serum leptin concentration and evaluated the genetic and phenotypic relationships of serum leptin concentration with performance, efficiency of gain, and carcass merit. Serum leptin concentration was moderately heritable (h2 = 0.34 ± 0.13) and averaged 13.91 (SD = 5.74) ng/mL. Sire breed differences in serum leptin concentration correlated well with breed differences in body composition. Consequently, ultrasound backfat (27%), carcass 12th-rib fat (31%), ultrasound marbling (14%), and carcass marbling (15%) were less in Charolais- than Angus-sired steers (P < 0.001). Conversely, carcass LM area (P = 0.05) and carcass lean meat yield (P < 0.001) were greater in Charolais- compared with Angus-sired steers. Steers with greater serum leptin concentration also had greater DMI (P < 0.001), greater residual feed intake (P = 0.04), and partial efficiency of growth (P = 0.01), but did not differ in feed conversion ratio (P > 0.10). Serum leptin concentration was correlated phenotypically with ultrasound backfat (r = 0.41; P < 0.001), carcass 12th-rib fat (r = 0.42; P < 0.001), ultrasound marbling (r = 0.25; P < 0.01), carcass marbling (r = 0.28; P < 0.01), ultrasound LM area (r = –0.19; P < 0.01), carcass LM area (r = –0.17; P < 0.05), lean meat yield (r = –0.38; P < 0.001), and yield grade (r = 0.32; P < 0.001). The corresponding genetic correlations were generally greater than the phenotypic correlations and included ultrasound backfat (r = 0.76 ± 0.19), carcass 12th-rib fat (r = 0.54 ± 0.23), ultrasound marbling (r = 0.27 ± 0.22), carcass marbling (r = 0.76 ± 0.21), ultrasound LM area (r = –0.71 ± 0.19), carcass LM area (r = –0.75 ± 0.20), lean meat yield (r = –0.59 ± 0.22), and yield grade (r = 0.39 ± 0.26).


Innovative concept: Serum leptin concentration can be a valuable tool that can be incorporated into appropriate selection programs to favorably improve the carcass merit of cattle.


Cushman, R. A., Allan, M. F., Thallman, R. M., Cundiff, L. V. 2007 Characterization of biological types of cattle (Cycle VII):Influence of postpartum interval and estrous cycle length on fertility. Journal of Animal Science, 85:2156-2162.


Keywords: beef breed, postpartum interval, reproductive efficiency


Short summary: The current study tested the hypotheses that:1) breeds vary in postpartum interval to estrus (PPIE) and estrous cycle length, 2) a longer estrous cycle immediately before breeding increased pregnancy rates, and 3) a greater number of cycles before breeding increased conception rates. The postpartum interval to estrus, estrous cycle length, and number of cycles before breeding were examined in F1 cows (n = 519) obtained from mating Hereford, Angus, and MARC III cows to Hereford, Angus, Simmental, Limousin, Charolais, Gelbvieh, and Red Angus sires. Cows were classified as having 0, 1, 2, or 3 observed estrous cycles before breeding. Sire breed of the cow influenced length of the PPIE and number of cycles before the start of breeding (P <0.001). Simmental-sired cows had the shortest PPIE and greatest number of cycles before breeding, whereas Limousin-sired cows had the longest PPIE and least number of cycles before breeding. Cows with a greater number of cycles before breeding did not have greater conception rates than cows that had not exhibited standing estrus before breeding (P = 0.87). In cows that cycled before breeding, the length of the estrous cycle immediately before breeding was influenced by dam breed and BCS (P <0.01). Cows out of Hereford dams had shorter estrous cycles than cows out of MARC III or Angus dams, and estrous cycle length increased as BCS increased. Conception rate decreased as length of the estrous cycle immediately before breeding increased (P = 0.05, – 2.2% per d of cycle length).


Innovative concept: Genetic improvement in reproductive efficiency through selection is difficult because many reproductive traits are binomial and have low heritabilities. Therefore, greater characterization of reproductive phenotypes is needed to understand the components of reproductive efficiency before generating genetic markers for its traits.


Alexander, L. J., Geary, T. W., Snelling, W. M., MacNeil M. D. 2007 Quantitative trait loci with additive effects on growth and carcass traits in a Wagyu-Limousin F2 population. Animal Genetics, 38 (4):413–416.


Keywords: carcass, cattle, Limousin, myostatin, quantitative trait loci, Wagyu


Short summary: A whole-genome scan for carcass traits [average daily gain during the pre-weaning, growth and finishing periods; birth weight; hot carcass weight and longissimus muscle area (LMA)] was performed on 328 F2 progeny produced from Wagyu × Limousin-cross parents derived from eight founder Wagyu bulls. Nine significant (P ≤ 0.05) and four suggestive (P ≤ 0.1) QTL affecting seven growth and carcass traits were identified. Significant QTL were located on bovine chromosomes 2, 4, 7, 9, 12, 16, 17 and 29. A QTL previously reported on chromosome 2 for LMA was also detected in this study.


Innovative concept: The results provide insight into genetic differences between the Wagyu and Limousin breeds.


Baker, M. J., Tedeschi, L. O., Fox, D. G., Henning, W. R., Ketchen, D. J. 2006. “Using ultrasound measurements to predict body composition of yearling bulls” J. Anim Sci. 84:2666-2672.

KEY WORDS: Beef bull, Body composition, Carcass trait, Dry matter required, Ultrasound

SUMMARY: Carcass traits have been successfully used to determine body composition of steers. Body composition, in turn, has been used to predict energy content of ADG to compute feed requirements of individual animals fed in groups. This information is used in the Cornell value discovery system (CVDS) to predict DM required (DMR) for the observed animal performance. In this experiment, the prediction of individual DMR for the observed performance of group-fed yearling bulls was evaluated using energy content of gain, which was based on ultrasound measurements to estimate carcass traits and energy content of ADG. One hundred eighteen spring-born purebred and crossbred bulls (BW = 288 ± 4.3 kg) were sorted visually into 3 marketing groups based on estimated days to reach USDA low Choice quality grade. The bulls were fed a common high-concentrate diet in 12 slatted-floor pens (9 to 10 head/pen). Ultrasound measurements including back-fat (uBF), rump fat, LM area (uLMA), and intramuscular fat were taken at approximately 1 yr of age. Carcass measurements including HCW, backfat over the 12th to 13th rib (BF), marbling score (MRB), and LM area (LMA) were collected for comparison with ultrasound data for predicting carcass composition. The 9th to 11th-rib section was removed and dissected into soft tissue and bone for determination of chemical composition, which was used to predict carcass fat and empty body fat (EBF). The predicted EBF averaged 23.7 ± 4.0%. Multiple regression analysis indicated that carcass traits explained 72% of the variation in predicted EBF (EBF = 16.0583 + 5.6352 x BF + 0.01781 x HCW + 1.0486 x MRB – 0.1239 x LMA). Because carcass traits are not available on bulls intended for use as herd sires, another equation using predicted HCW (pHCW) and ultrasound measurements was developed (EBF = 39.9535 x uBF – 0.1384 x uLMA + 0.0867 x pHCW – 0.0897 x uBF x pHCW – 1.3690). This equation accounted for 62% of the variation in EBF. The use of an equation to predict EBF developed with steer composition data overpredicted the EBF predicted in these experiments (28.7 vs. 23.7%, respectively). In a validation study with 37 individually fed bulls, the use of the ultrasound-based equation in the CVDS to predict energy content of gain accounted for 60% of the variation in the observed efficiency of gain, with 1.5% bias, and identified 3 of the 4 most efficient bulls.

Sissom E. K., Reinhardt C. D., Johnson, B. J. 2006. “Melengestrol acetate alters muscle cell proliferation in heifers and steers”. J. Anim Sci. 84:2950-2958.

KEY WORDS: Bovine, Carcass, Insulin-like growth factor-I, Melengestrol acetate, Progesterone, Satellite cell

SUMMARY: In vitro experiments were performed to investigate the effects of melengestrol acetate (MGA) or progesterone (P4) on bovine muscle satellite cells and C2C12 myoblasts. Addition of MGA at physiological and supraphysiological concentrations resulted in a dose-dependent decrease (P < 0.05) in DNA synthesis as measured by 3H]-thymidine incorporation (TI). Similarly, P4 addition (0.01 nM) reduced (P < 0.05) TI. Addition of MGA (10 nM) increased (P < 0.05) IGF-I mRNA abundance but did not affect myogenin mRNA. Progesterone addition (10 nM) increased myogenin mRNA abundance (P < 0.05). In C2C12 cultures, P4 addition resulted in a dose-dependent decrease in TI. The antiprogestin RU486, in combination with MGA or P4, also resulted in reduced (P < 0.05) TI. Treatment with RU486 alone had a negative effect (P < 0.05) on TI that was similar to the progestins. Treatment of C2C12 myoblasts with MGA (100 nM) resulted in an increase (P < 0.05) in myogenin mRNA. These studies suggest that progestins may reduce satellite cell proliferation, ultimately affecting carcass composition.

Albrecht, E., Teuscher, F., Ender, K., Wegner, J. 2006. “Growth- and breed-related changes of muscle bundle structure in cattle” J. Anim Sci. 84:2959-2964.

KEY WORDS: Breed, Cattle, Growth, Meat quality, Muscle fiber, Primary bundle

SUMMARY: The objective of this study was to investigate the changes in muscle fiber bundles of cattle of different breeds during growth. Different numbers of muscle fibers are surrounded by connective tissue to form bundles macroscopically visible as meat fibers or meat grain, a common meat quality trait. To determine the influence of breed and age on morphological characteristics of muscle fiber bundles, 4 cattle breeds with different growth impetus and muscularity were reared and slaughtered under experimental conditions. German Angus, a typical beef cattle; Galloway, a smaller beef type; Holstein Friesian, a dairy type; and double-muscled Belgian Blue, an extreme type for muscle growth, were used. Between 5 and 15 bulls of each breed were slaughtered at 2, 4, 6, 12, or 24 mo of age, and slices of semitendinosus muscle were removed. Muscle structure characteristics were determined by computerized image analysis. During growth, the muscle cross-sectional area enlarged (P < 0.001) about 5-fold in double-muscled Belgian Blue bulls and about 4-fold in the other breeds. This was a result of the enlargement (P < 0.001) of primary bundles and muscle fibers. The bundle size was similar (P 0.15) in bulls of German Angus and Galloway in all age groups and was doubled (P < 0.001) in double-muscled Belgian Blue animals from 4 mo of age on. The Holstein Friesian bulls had the smallest (P < 0.001) muscle fiber bundles at 24 mo of age. The number of muscle fibers per bundle and the number of bundles per muscle remained nearly constant (P > 0.05) during growth. This supports the existing view that the structure of the muscle is already fixed in prenatal life. The double-muscled Belgian Blue bulls showed a more than 2.5-fold greater (P < 0.001) number of muscle fibers per primary bundle compared with the other breeds investigated. The larger muscle fiber bundles led to a smaller amount of connective tissue per muscle area in double-muscled cattle. The coarser grain of meat in double-muscled Belgian Blue bulls and in older animals was not related to greater shear force values.

Berthiaume, R., Mandell, I., Faucitano, L., Lafrenière, C. 2006. “Comparison of alternative beef production systems based on forage finishing or grain-forage diets with or without growth promotants: 1. Feedlot performance, carcass quality, and production costs”. J. Anim. Sci. 84: 2168-2177.

KEYWORDS: Beef production system, Feedlot performance, Forage finishing, Production cost

SUMMARY: Forty Angus-cross steers were used to evaluate 5 beef cattle management regimens for their effect on growth performance, carcass characteristics, and cost of production. A 98-d growing phase was incorporated using grass silage with or without growth promotants (trenbolone acetate + estradiol implants, and monensin in the feed) or soybean meal. Dietary treatments in the finishing phase were developed, with or without addition of the same growth promotants, based on exclusive feeding of forages with minimal supplementation or the feeding of barley-based diets. Overall, ADG for animals treated with growth promotants or fed supplemented diets (soybean meal and barley) was increased (P < 0.01) by 25 and 21%, respectively, compared with steers reared on grass silage alone and not treated with growth promotants. Except for HCW (P < 0.01), the use of growth promotants did not affect carcass measurements. Increasing the proportion of barley in the diet of steers finished on forage produced a heavier HCW (P < 0.01) and a greater (P < 0.01) quality grade. Because of their lower HCW and quality grade, cattle targeted to a forage-fed, nonimplanted beef market would need to garner a 16% premium to be economically competitive with cattle finished conventionally.

Picard, B., Jurie, C., Duris, M. P., Renand, G. 2006. “Consequences of selection for higher growth rate on muscle fibre development in cattle”. Livestock Science. 102: 107-120.

KEY WORDS: Muscle hypertophy, Muscle fibre development, Contractile and metabolic properties

SUMMARY The aim of this study was to analyse the consequences of selection on the development of muscle fibres in the semitendinosus muscle of two groups of Charolais bulls with a high or low muscle growth index. Muscle fibre kinetics were analysed during foetal life (110, 180, 210, 260 days of gestation) and after birth (3 weeks, 9, 15, 19 months). The weight, length and area of muscle were measured. The total number of fibres and muscle fibre area were calculated for each stage. The contractile properties of fibres were revealed by immunohistochemistry. Oxidative capacity of individual fibres was determined on serial sections stained for Succinate Dehydrogenase. Finally, whole muscle metabolic properties were measured on homogenates of muscle with analysis of the activity of Lactate Dehydrogenase (glycolytic) and Isocitrate Dehydrogenase (oxidative). The main results showed muscle hypertrophy in bulls with a high growth potential due to a higher total number of fibres (indicating hyperplasia). From the last trimester of gestation onwards, this is associated with particular contractile and metabolic properties, with mainly a higher proportion of IIX fibres (fast glycolytic). However, the delayed physiological maturity of these bulls induced a delay in the plasticity of muscle fibres after birth. Consequently, the effects of selection on growth rate on muscle properties are not evident at each stage.

Hocquette, J. F., Sauerwein, H., Higashiyama, Y., Picard, B., Abe, H. 2006. “Prenatal developmental changes in glucose transporters, intermediary metabolism and hormonal receptors related to the IGF/insulin-glucose axis in the heart and adipose tissue of bovines”. Reproduction Nutrition Development. 46: 257-272.

KEY WORDS: Glucose transporter, Heart, Adipose tissue, Bovine, Foetal development

SUMMARY Glucose transporter ontogenesis is likely to play a key role in glucose uptake by foetal tissues in order to satisfy their energy requirements. We thus investigated developmental changes in the bovine heart and perirenal adipose tissue in two glucose transporter isoforms, namely GLUT1 and GLUT4, the latter being responsible for the regulation of glucose uptake by insulin. Other key players of the glucose/insulin axis were also assessed. Plasma glucose concentration in the foetus was lower at 8 and 8.5 months of age than previously. In the heart, GLUT1 protein level markedly decreased between 3 and 4 months of age, whereas the number of insulin and IGF-I binding sites continually decreased, especially between 7 and 8 or 8.5 months of age. On the contrary, the GLUT4 level increased until 8 months of age and remained high until 2 weeks after birth. The activities of enzymes of glucose metabolism (namely phosphofructokinase [PFK] and lactate dehydrogenase [LDH]) increased throughout gestation and reached a plateau at 6 and 8.5 months of age for PFK and LDH, respectively. The activities of enzymes involved in fatty acid metabolism increased especially at birth. In perirenal adipose tissue, high mitochondrial activity was detected before birth which is a characteristic of brown adipose tissue. Furthermore, lipoprotein lipase activity and GLUT4 protein level markedly increased to reach a maximum at 6-7 and 8 months of age, and sharply decreased thereafter, whereas GLUT1 protein level increased between 6 and 7 months of age. In conclusion, considerable changes in the regulation of the insulin/glucose axis were observed from 6 months onwards of foetal development in both the heart and adipose tissue of cattle, which probably alters the potential of these tissues to use glucose or fat as energy sources.

Coffey, M. P., Hickey, J., Brotherstone, S. “Genetic Aspects of Growth of Holstein-Friesian Dairy Cows from Birth to Maturity”. Journal of Dairy Science. 89: 322-329

KEYWORDS: Growth, Dairy heifer, Genetic selection

SUMMARY:In general, genetic selection is applied after first calving to traits that manifest themselves during the animal’s productive life, mostly during the early part of productive life. This selection policy has had undesirable correlated responses in other economically important traits, such as health and fertility, and may also have had an effect on the growth of animals both during productive life and before first calving. In this study, we analyzed the growth trajectory of dairy heifers that had been selected for maximum production of combined fat and protein (measured in kg; select line) or for average production (control line) in the United Kingdom. Before first calving, these divergent lines were managed as a single group. Select line heifers grew faster than did control line heifers. They were also heavier at first calving, but by the end of 3 lactations, the lines were not significantly different in live weight. Selection primarily for yield and for other traits has led to heifers that grow faster and reach higher growth rates earlier in life. A genetic analysis of birth, weaning, and calving weights yielded heritability estimates of 0.53 (birth weight), 0.45 (weaning weight), and 0.75 (calving weight). Confidence intervals for the genetic correlations between the traits indicated that these BW traits are not under the same genetic control.

Bradford, B. J., Oba, M., Ehrhardt, R. A., Boisclair, Y. R., Allen, M. S. “Propionate is not an important regulator of plasma leptin concentration in dairy cattle”. Domestic Animal Endocrinology. 2006. 30: 65-75.

KEYWORDS: Leptin, Propionate, Dairy cow, Adipose tissue

SUMMARY:Propionate was recently shown to increase leptin synthesis in rodents. To determine if a similar effect occurs in ruminants, propionate was administered to lactating dairy cows. In experiment 1, 31 cows were given an intrajugular Na propionate bolus (1040 μmol/kg body weight), increasing plasma propionate from 160 to 5680 μM and plasma insulin from 6.8 to 77.8 μIU/mL. Plasma leptin concentration decreased from 2.11 ng/mL before bolus to 1.99 ng/mL after dosing (P < 0.05) with no differences in leptin concentrations at 20, 50, and 100 min post-bolus (P > 0.10). In experiment 2, 12 cows were used in a duplicated 6 × 6 Latin square experiment to assess the dose–response effect of ruminal propionate infusion on plasma leptin concentration. Sodium propionate was infused at rates of 0, 260, 520, 780, 1040, or 1300 mmol/h, while total short-chain fatty acid infusion rate was held constant at 1300 mmol/h by addition of Na acetate to the infusate. Coccygeal blood was sampled following 18 h of infusion. Increasing the rate of propionate infusion linearly increased plasma propionate concentration from 180 to 330 μM (P < 0.001) and plasma insulin concentration from 6.7 to 9.1 μIU/mL (P < 0.05). There was a quadratic response in plasma leptin concentration (P = 0.04) with a maximum at 780 mmol/h propionate, but leptin concentrations increased by no more than 8% relative to the 0 mmol/h propionate infusion. Leptin concentrations were correlated with insulin concentrations but not with propionate concentrations in plasma. Propionate is not a physiological regulator of leptin secretion in lactating dairy cows.

Therkildsen, M. “Muscle protein degradation in bull calves with compensatory growth” 2005. Livestock Production Science. 98: 205-218.

KEY WORDS: Muscle protein turnover, Calpain, Fractional breakdown rate, Insulin-like growth factor 1

SUMMARY:Twelve 5-month-old bull calves were allocated to two feeding strategies: AA, 6 calves were fed ad libitum 34 weeks; and RA, 6 calves were fed restrictively for 14 weeks with an intake of 50% of the metabolic energy and protein eaten by the AA calves, followed by ad libitum feeding for 20 weeks. At the end of the 14-week restriction period, and after 2, 5, 8, 11, 14 and 17 weeks of re-alimentation, urine, blood and muscle biopsy samples from M. longissimus dorsi (LD) were collected. The urine was analysed for 3-methylhistidine for determination of the fractional breakdown rate of muscle protein (FBR). The FBR was depressed during restricted feeding (1.4 versus 2.0%/day; P = 0.05), however, during re-alimentation where the calves exerted compensatory growth, the FBR increased and reached a maximum after 5 weeks into this period (3.1 versus 1.9%/day; P < 0.001). The maximal FBR in the RA calves coincided with a maximum concentration of RNA and DNA in LD, and a maximal fractional rate of growth. The activity of μ-calpain in LD and the concentration of IGF-I in serum were decreased at the end of the restriction period but increased as soon as energy was offered ad libitum. The results support the hypothesis that muscle protein turnover is affected by a restriction/re-alimentation feeding strategy, and that muscle protein degradation reaches a maximum during the re-alimentation period, which exceeds that of control animals. .

Listrat, A., Hocquette, J. F., Picard, B., Ménissier, F., Djiane, J., Jammes, H. “Growth hormone receptor gene expression in the skeletal muscle of normal and double-muscled bovines during foetal development” 2005. Reproduction Nutrition Development. 45: 393-403

KEYWORDS: Muscle, Bovine, Receptor, Growth hormone, In situ hybridisation

SUMMARY The expression of the growth hormone receptor (GHR) gene was investigated in semitendinosus muscle during bovine foetal development in both normal and double-muscled Charolais foetuses which differ with respect to muscle development. Northern-blot analysis of foetal muscle RNA preparations with a GHR cDNA probe identified the 4.5 kb GHR mRNA as early as 130 days post-conception. In double-muscled animals, the expression of GHR mRNA increased from 130 to 210 days of gestation while it stayed stable in normal ones. It was significantly higher (P < 0.05) in double-muscled foetuses compared to normal ones from the second third of gestation. Northern-blot analysis of foetal muscle RNA preparations from both genotypes with a -actin cDNA probe, revealed lower -actin gene expression in double-muscled foetuses than in normal ones, suggesting a delay in the differentiation of muscle cells. In situ hybridisation revealed the localisation of specific GHR mRNA in muscle cells at all gestation stages analysed (130, 170, 210 days post-conception) but not in connective tissue surrounding the muscle cells. At the adult stage, the hybridisation signal was also very high and observed in muscle cells only. These results show the ontogeny of GHR mRNA in bovine muscle and demonstrate a difference between normal and double-muscled animals.

Altarriba, J., Varona, L., Moreno, C., Yagüe, G., Sañudo, C. “Consequences of selection for growth on carcass and meat quality in Pirenaica cattle”. 2005. Livestock Production Science. 95: 103-114.

KEYWORDS: Correlated response, Growth, Carcass quality, Meat quality, Beef cattle.

SUMMARY The male progeny of nine bulls used in artificial insemination were sampled to determine the effects of selection for weight at 210 days of age (W210) on carcass and meat quality in the Pirenaica cattle breed. For each of the 125 male offspring raised in experimental conditions, we measured 38 variables (y) defining carcass and meat quality. In turn, the breeding values of those animals for the W210 trait (û210) were calculated without their own record and without data of maternal siblings. Indirect responses were estimated from the slope of the covariate between the selection index (û210) and the phenotype of those variables (b(y, û210)). We derived that the covariate depends on the genetic correlation and the genetic variances of the selection index and the trait. Consequently, this method provides an unbiased estimator of the correlated response, without requiring an estimate of the genetic correlation. We conclude that, in the Pirenaica breed, selection for W210 produces animals with higher live- and carcass weights at slaughter, wider carcasses, deeper and longer legs with a greater perimeter, and greater loin surface. Genetic changes were not detected in dressing percentage and physicochemical or sensorial parameters of meat quality.

Curi, R. A., Oliveira, H. N., Silveira, A. C., Lopes, C. R. “Association between IGF-I, IGF-IR and GHRH gene polymorphisms and growth and carcass traits in beef cattle”. 2005. Livestock Production Science. 94: 159-167.

KEYWORDS: Beef cattle, Polymorphisms, Candidate gene, Growth, Carcass.

SUMMARY Molecular biology techniques are of help in genetic improvement since they permit the identification, mapping and analysis of polymorphisms of genes encoding proteins that act on metabolic pathways involved in economically interesting traits. The somatotrophic axis, which essentially consists of growth hormone releasing hormone (GHRH), growth hormone (GH), insulin-like growth factors I and II (IGF-I and IGF-II), and their associated binding proteins and receptors (GHRHR, GHR, IGF-IR and IGF-IIR), plays a key role in the metabolism and physiology of mammalian growth. The objectives of the present study were to estimate the allele and genotype frequencies of the IGF-I/SnaBI, IGF-IR/TaqI and GHRH/HaeIII gene polymorphisms in different genetic groups of beef cattle and to determine associations between these polymorphisms and growth and carcass traits. For this purpose, genotyping was performed on 79 Nellore animals, 30 Canchim (5/8 Charolais+3/8 Zebu) animals and 275 crossbred cattle originating from the crosses of Simmental (n=30) and Angus (n=245) sires with Nellore females. In the association studies, traits of interest were analyzed using the GLM procedure of SAS and least square means of the genotypes were compared by the Tukey test. Associations of IGF-I/SnaBI genotypes with body weight and subcutaneous backfat were significant (p<0.05), and nearly significant for longissimus dorsi area (p=0.06), with the BB genotype being favorable compared to the AB genotype. No significant associations were observed between this polymorphism and weight gain or carcass yield (P>0.05). The IGF-IR/TaqI and GHRH/HaeIII polymorphisms showed no association with production traits.

Jurie, C., Martin, J. F., Listrat, A., Jailler, R., Culioli, J., Picard, B. (2005). “Effects of age and breed of beef bulls on growth parameters, carcass and muscle characteristics”. Animal Science. 2005. 80: 257-264.

KEYWORDS: Age, Beef bulls, Breed differences, Carcass composition, Muscle

SUMMARY: The effects of age and breed on growth parameters, carcass and muscle characteristics of bulls, slaughtered at 15, 19 and 24 months of age, were analysed in four French breeds : Aubrac (AU), Charolais (CH), Limousin (LI), and Salers (SA). Muscle characteristics were determined in three muscles : longissimus thoracis (LT), semitendinosus (ST) and triceps brachii (TB). They included : (1) the % frequency, cross-sectional area and % area of
bre types, which were classied according to the contractile nature of the bres and their metabolic properties (SO slow oxidative, FOG fast oxidative glycolytic and FG fast glycolytic); (2) the isocitrate dehydrogenase (ICDH) and lactate dehydrogenase (LDH) activities, representative of oxidative and glycolytic metabolism respectively; and (3) the total and insoluble collagen contents. In the four breeds, the average daily gain and the food efciency decreased with age ( P < 0•001). The carcass characteristics (muscle, fat and bone weights) increased with age ( P < 0•001). The increase of muscle carcass weight with slaughter age was in parallel with the increase in cross-sectional area of individual muscle bres. Oxidative bre (SO and FOG) areas increased more between 15 and 24 months than glycolytic bre (FG) area. Differences between muscles in increases in areas of muscle bres were consistent : the increase was greater for TB than ST and LT. The muscles studied became more slow and more oxidative above 19 months of age, as evidenced by the fact that the SO % frequency ( P < 0•001) and % area ( P < 0•001) and ICDH activity ( P < 0•05) increased, and LDH activity decreased ( P < 0•01). Insoluble collagen content decreased between 15 and 19 months ( P < 0•001), and both total ( P < 0•01) and insoluble ( P < 0•001) collagen contents increased from 19 months. So carcass characteristics were modied between 15 and 24 months, and muscle characteristics were especially modied from 19 months of age. In addition, differences in slaughter data between breeds were clear and consistent, whereas those of muscle characteristics were few and not consistent.

Williams, C. B. (2005). “Technical Note: A dynamic model to predict the composition of fat-free matter gains in cattle. Journal of Animal Science”. 83: 1262-1266.

KEYWORDS: Body Composition, Cattle, Model, Protein.

SUMMARY: Composition of empty BW (EBW) was described in terms of ether-extractable lipid (FAT) and fat-free matter (FFM), and the terms dEBW, dFAT, and dFFM were used to represent daily gains in these components. The dFFM comprised protein, water, and ash, and a model was developed to predict the composition of dFFM. The conceptual approach used in model development was based on experimental data that showed as cattle grew from birth to maturity: 1) the water content of FFM decreased and the protein and ash content increased; 2) the protein content of FFM increased at a decreasing rate; and 3) the protein-to-ash ratio in the fat-free DM was approximately constant. These results suggest that the protein content of dFFM would be high at birth and decrease at a decreasing rate as the animal grows. The protein content of dFFM was predicted as a function of the fraction of dEBW that was dFFM, FAT content of EBW, and dFFM. A fixed protein-to-ash ratio of 4.1:1 was used to calculate the quantity of ash, and water was obtained as a residual. Growth and body composition of Hereford x Angus steers from birth to 500 kg BW were simulated with a previously published model using the experimental growth data as input, and the model under discussion was used to predict the composition of dFFM. Predicted response curves of the EBW components over the growth period were similar in shape to observed data. Predicted curvilinearity in response of protein weight against FFM weight for Hereford x Angus steers was similar to observed data. The standard error about the regression of predicted on observed protein weight was 1.87 kg, and the average bias of the model was to underpredict protein weight by 0.64%. Compared with using a constant value for the protein fraction of dFFM, the model provided more accurate predictions of dEBW in an independent evaluation data set.

Albuquerque, L.G., Meyer,K. (2005). “Estimates of covariance functions for growth of Nelore cattle applying a parametric correlation structure to model within-animal correlations”. Livestock Production Science. 93:213-222.

KEYWORDS: Covariance functions, Nelore cattle, Parametric correlation structure.

SUMMARY: A total of 20,065 weights recorded on 3016 Nelore animals were used to estimate covariance functions for growth from birth to 630 days of age, assuming a parametric correlation structure to model within-animal correlations. The model of analysis included fixed effects of contemporary groups and age of dam as quadratic covariable. Mean trends were taken into account by a cubic regression on orthogonal polynomials of animal age. Genetic effects of the animal and its dam and maternal permanent environmental effects were modelled by random regressions on Legendre polynomials of age at recording. Changes in direct permanent environmental effect variances were modelled by a polynomial variance function, together with a parametric correlation function to account for correlations between ages. Stationary and nonstationary models were used to model within-animal correlations between different ages. Residual variances were considered homogeneous or heterogeneous, with changes modelled by a step or polynomial function of age at recording. Based on Bayesian information criterion, a model with a cubic variance function combined with a nonstationary correlation function for permanent environmental effects, with 49 parameters to be estimated, fitted best. Modelling within-animal correlations through a parametric correlation structure can describe the variation pattern adequately. Moreover, the number of parameters to be estimated can be decreased substantially compared to a model fitting random regression on Legendre polynomial of age.

Sudre, K., Cassar-Malek, I., Listrat, A., Ueda, Y., Leroux, C., Jurie, C., Auffray, C., Renand, G., Martin, P., Hocquette, J. F. (2005). “Biochemical and transcriptomic analyses of two bovine skeletal muscles in Charolais bulls divergently selected for muscle growth”. Meat Science. 70: 267-277.

KEYWORDS: Beef, Muscle growth, Transcriptomic analysis, Selection.

SUMMARY: This work aimed to investigate the consequences of muscle growth selection on muscle characteristics. An oxidative muscle (Rectus abdominis, RA) and a glycolytic one (Semitendinosus, ST) were studied in two groups of six extreme young Charolais bulls of high or low muscle growth. Mitochondrial activity was lower in muscles of bulls with high muscle growth. Transcriptomic studies allowed the identification of putatively differentially expressed genes. The differential expression between genetic types of two genes in RA (a heat shock protein and a thyroid receptor interacting protein) and of seven genes in ST (including LEU5, tropomyosin 2, and sarcosin) was confirmed by different statistical approaches or Northern blot analysis, as well as the differential expression of five genes (including PSMD4 and DPM synthase) between RA and ST. Both biochemical and transcriptomic results indicate that selection on muscle growth potential is associated with reduced slow-oxidative muscle characteristics. Further studies are required to understand the physiological importance of genes whose expression is changed by selection.

Perry, D., Thompson, J. M. (2005) “The effect of growth rate during backgrounding and finishing on meat quality traits in beef cattle”. Meat. Sci. 69: 691-702

KEYWORDS: Growth rate, Tenderness, Meat quality, Palatability, Shear force, Compression

SUMMARY: The relationship between growth rate and meat tenderness was investigated in ≈7000 cattle from temperate and tropically adapted breeds, finished on either pasture or in a feedlot to one of three market weights. Growth rate was calculated from weaning to the beginning of finishing (backgrounding) and over the finishing period, for both contemporary groups and individuals within these groups. Shear force and compression of longissimus lumborum (striploin) and semitendinosus (eye round) were measured at two days ageing, and palatability of the striploin at 14 days ageing. Analyses assessed the importance of growth rate during backgrounding and finishing on both a within group and between group basis. Where significant in individual animals, increased growth rate resulted in more palatable or tender meat, but the results were not consistent between breed types, locations, or the two muscles sampled. The most consistent relationship was an increase in palatability of the striploin with increased growth rate during finishing. Increased growth rate of groups during backgrounding improved palatability consistently across breed types, finish and location; however most of this relationship was accounted for by difference in mean group age at slaughter.

Berry, D. P., Horan, B., Dillon, P. (2005) “Comparison of growth curves of three strains of female dairy cattle”. Anim. Sci. 80: 151-160

KEYWORDS: Dairy cattle, Growth curve, Strain differences

SUMMARY: The objective of the present study was to compare growth curves for live weight (LW) and body size of three strains of female dairy cattle reared under common environments in Ireland. One strain (HP) was selected from a predominantly North-American/European Holstein-Friesian genetic pool selected for high milk production. The second strain (HD) represented a predominantly North-American/European Holstein-Friesian genetic pool selected for high milk production but with greater selection emphasis on functional non-production traits. The third strain (NZ) consisted of New Zealand Holstein-Friesian females of high genetic merit for profitability in New Zealand. The data consisted of 99 animals (33 animals in each strain) with records on LW, length, girth and height from birth to a minimum of 594 days of age. The von Bertalanffy growth function was fitted to each animal’s records separately and least-squares analyses were used to investigate the effect of strain on birth LW/body size, parameters of the growth function and average daily gains. Average mature live weight of the HD animals (591 kg) was significantly larger than that of the HP (566 kg) or NZ (543 kg) strain; the HD strain matured more slowly. The HD (134 cm) and HP (135 cm) strains were significantly taller than the NZ (128 cm) strain. Although the data set was relatively small there are indications that dairy females of North-American genetic origin were heavier at birth, grew faster, and were heavier and taller at maturity than dairy females of New Zealand origin.

Bruns, K., W., Pritchard, R. H., Boggs, D, L. (2005) The effect of stage of growth and implant exposure on performance and carcass composition in steers

KEYWORDS: Beef, body composition, implants, estradiol, trenbolone acetate

SUMMARY: This study was conducted to quantify the growth of intramuscular fat relative to changes in body composition in steers fed high-energy diets and implated at two different points in the finishing phase growth curve. Angus and Angus x Limousin cross steers (n = 182; initial BW = 309 ± 27.8 kg) were used to evaluate the influence of an estradiol–trenbolone acetate implant (containing 24 mg of estradiol and 125 mg of trenbolone acetate). Treatments were 1) control, no implant (NI); 2) early implant (EI) on d 1 (BW = 309 kg); or 3) delayed implant (DI) on d 57 (BW = 385 kg). Comparisons were also made between the NI and implanted treatments (I; EI + DI). Steers were procured at weaning and were backgrounded (47 d) before the initiation of the experiment. Days on feed were constant across treatment. After 56 d, average daily gain (ADG) and gain-to-feed ratio (G:F) were improved by implants. At d 57, predicted carcass composition did not differ among treatments. From 57 to 112 d, DI caused higher ADG than NI or EI and higher G:F. Cumulative ADG and G:F were improved by implants with no differences between treatments that involved implants. Implanting increased dressing percentage and increased hot carcass weight and LM area. Rib fat and kidney, pelvic, and heart fat were not affected by treatment, and treatment had no effect on the whole carcass proportions of fat, protein, or water. Marbling scores were decreased by EI but not by DI. The percentage of i.m. fat content of the LM was decreased by EI and was not affected by DI. The results of this study suggest that growth of i.m. fat is sensitive to anabolic growth promotants administered during early periods of growth.