Cow Genotypes Research Articles

The effect of two levels of nutrient intake on milk production of two dairy cow genotypes

Breeding goals differ for different breeds of dairy cattle. For example the breeding programmes for Holstein-Friesian (HF) animals have been based primarily on improved milk production with little emphasis on functional traits such as fertility. In contrast, Norwegian (NC) dairy cattle have been bred using a multi-trait selection procedure for 25 years. These differences in selection procedures for the two breeds may have major effects on overall herd output and profitability with the forage-based systems of milk production employed in Northern Ireland. The objective of the present paper is to present the effects of two levels of nutrient input on food intake and utilisation, and animal performance of the two breeds, with diets based on grass silage during the first and second lactation.

Voluntary feed intake in autumn calving continental x dairy suckler cows given a grass silage based diet ad libitum

An understanding of the dry matter intake (DMI) capacity of suckler cows is crucial to the provision of adequate nutrition during lactation. However, quantitative data on the likely feed intake patterns of modern continental x dairy suckler cow genotypes is scarce. The objective of the current experiment was to determine voluntary DMI in Simmental x Holstein/Friesian (SIM) and Belgian Blue x Holstein/Friesian (BB) autumn calving suckler cows offered a grass silage based diet ad libitum.

Associations Between Casein Haplotypes and First Lactation Milk Production Traits in Finnish Ayrshire Cows

The objective of this study was to estimate the effects of β-κ-casein (CN) haplotypes on first-lactation milk production traits. The β-κ-CN haplotypes were deduced using information on β- and κ-CN genotypes of cows and their sires for 16,973 Finnish Ayrshire cows that had at least nine paternal half sibs. Effects of CN haplotypes on milk production traits were estimated for one haplotype at a time using an animal model, which included the fixed effects for calving year and month, age at calving, days open, β-lactoglobulin, and a β-κ-CN haplotype. Differences in milk production traits were also estimated between haplotype combinations A1A+A2B and A1B+A2A within β-κ-CN genotype A1A2AB and between combinations A1E+A2A and A1A+A2E within genotype A1A2AE. The β-κ-CN haplotypes A2A and A2B were associated with high milk and protein yields and low fat content, and those that included the β-CN A1 allele were associated with low yields and high fat content. Protein content was affected by the κ-CN locus; haplotype A1B was associated with high protein content and A1E was with low protein content. The haplotype combination A1A+A2B was associated with 140kg more milk yield (P=0.045) and 0.03 percentage units less protein content (P=0.055) than combination A1B+A2A, and combination A1A+A2E showed 0.02 percentage units greater protein content (P=0.098) than A1E+A2A. These results indicate that genes linked to the CN loci contribute to the variation in milk yield and protein content.

Association of the Leu127 variant of the bovine growth hormone (bGH) gene with increased yield of milk, fat, and protein in Australian Holstein-Friesians

The occurrence of the Leu127/Val127 variants of the bovine growth hormone (bGH) gene and their effect on milk production traits was investigated in Australian Holstein-Friesian cattle. Animals were genotyped for the Leu127/Val127 variants, with RFLP methodology, using PCR and AluI digestion of PCR products (AluI-RFLP). Alleles Leu127 and Val127 occurred with frequencies of 82% and 18%, respectively. The quantitative effect of this polymorphic site on milk-production traits was estimated from lactation data and test-day data. Results from the 2 data sets consistently showed that the Leu127 allele is associated with higher production of milk, fat, and protein and is dominant to Val127. The average effects of the gene substitution are 95 L for milk yield, 7 kg for fat yield, and 3 kg for protein yield per lactation. This locus may be directly responsible for quantitative variation or it may be a marker for a closely linked quantitative trait locus (QTL) for milk-production traits in Australian dairy cattle. In either case, it will be useful as an aid to selection for improvement of milk production traits. As the Leu127 allele is dominant, selection of AI sires homozygous for the Leu127 allele (Leu127/Leu127) will result in maximum benefit without the need for genotyping cows.

Análise de polimorfismos do gene da kapa-caseína em fêmeas da raça Nelore e efeito sobre o peso à desmama de suas progênies

Informações sobre peso à desmama de um rebanho Nelore, após ajuste para idade padrão de 205 dias, sexo da cria, idade da mãe, touro e mês de desmama, foram utilizadas para separar as reprodutrizes em dois grupos, cujos produtos diferiam em peso. As médias ajustadas pelo método dos quadrados mínimos e erros-padrão para os grupos pesado (P) e leve (L) foram 163,21±2,18kg e 134,44±2,18kg, respectivamente, com 41 animais em cada grupo. Colheram-se amostras de sangue das reprodutrizes para o estudo de polimorfismos do gene da kapa-caseína, pela técnica de polymerase chain reaction-restriction fragment length polymorphism. A análise de um segmento do éxon IV do gene da kapa-caseína identificou os genótipos 71AA, 10AB e 1BB, com as freqüências de 0,92 e 0,08 para os alelos A e B, respectivamente. Os pesos à desmama dos produtos dos genótipos AA e AB foram, respectivamente, 147,73±2,38kg e 156,76±6,35kg. Os grupos P e L não diferiram entre si quanto às freqüências alélicas apresentadas para esse gene. O genótipo das reprodutrizes não afetou o peso à desmama de suas crias, existindo, portanto, outros efeitos genéticos e não genéticos de maior magnitude.

The effect of genetic merit and concentrate proportion in the diet on nutrient utilization by lactating dairy cows

Sixty Holstein/Friesian dairy cows, 28 of high genetic merit and 32 of medium genetic merit, were used in a continuous design, 2 (cow genotypes)×4 (concentrate proportion in diet) factorial experiment. High and medium merit animals had Predicted Transmitting Abilities for milk fat plus protein yield, calculated using 1995 as the base year (PTA95 fat plus protein), of 43·3 kg and 1·0 kg respectively. Concentrate proportions in the diet were 0·37, 0·48, 0·59 and 0·70 of total dry matter (DM), with the remainder of the diet being grass silage. During this milk production trial, 24 of these animals, 12 from each genetic merit, representing three animals from each concentrate treatment, were subject to ration digestibility, and nitrogen and energy utilization studies. In addition, the efficiency of energy utilization during the milk production trial was calculated.There were no genotype×concentrate level interactions for any of the variables measured (P>0·05). Neither genetic merit nor concentrate proportion in the diet influenced the digestibility of either the DM or energy components of the ration (P>0·05). When expressed as a proportion of nitrogen intake, medium merit cows exhibited a higher urinary nitrogen output and a lower milk nitrogen output than the high merit cows. Methane energy output, when expressed as a proportion of gross energy intake, was higher for the medium than high merit cows (P<0·05), while urinary energy output tended to decrease with increasing proportion of concentrate in the diet (P<0·05). In the calorimetric studies, neither heat energy production, milk energy output and energy retained, when expressed as a proportion of metabolizable energy intake, nor the efficiency of lactation (kl), were affected by either cow genotype or concentrate proportion in the diet (P>0·05). However when kl was calculated using the production data from the milk production trial the high merit cows were found to have significantly higher kl values than the medium merit cows (0·64 v. 0·59, P<0·05) while k l tended to fall with increasing proportion of concentrate in the ration (P<0·05). However in view of the many assumptions which were used in these latter calculations, a cautious interpretation is required.

The influence of dairy cow genetic merit on the direct and residual response to level of concentrate supplementation

Twenty-eight high genetic merit and 32 medium genetic merit Holstein/Friesian dairy cows with Predicted Transmitting Abilities for milk fat plus protein yield, calculated using 1995 as the base year (PTA95 fat plus protein) of 43·3 and 1·0 kg respectively, were used in a continuous design, 2 (cow genotypes)×4 (concentrate proportion in diet) factorial experiment consisting of eight treatments. Concentrate proportions in the diet were 0·37, 0·48, 0·59 and 0·70 of total dry matter (DM), while the forage component of the diet was grass silage. Diets were offered ad libitum in the form of a complete diet. Animals remained on these concentrate regimes for a mean of 84·7 days before completing a standard 98-day grazing period. At pasture, cows received either 5·0 or 6·0 kg concentrate daily according to turnout date. There were no significant genotype×nutrition interactions for any of the variables examined during either the indoor feeding or post-turnout grazing periods (P<0·05). Outputs of milk, fat, protein and fat + protein were greater for high merit cows than for medium merit animals (P<0·001). Milk output and milk protein output responses to increasing concentrate proportion were linear for both cow genotypes (P<0·001), while high merit animals showed a linear response in terms of milk fat plus protein output (P<0·01) with these responses being statistically parallel for both merits. High merit cows had a significantly higher DM intake than medium merit animals (P<0·01). With high merit animals, concentrate proportion had little effect on body tissue reserves, while medium merit animals showed a tendency for increased condition score and backfat thickness with increasing concentrate inclusions (P<0·05). In terms of the output of milk and milk constituents during the grazing period, there were no significant residual effects from winter concentrate feed rate (P>0·05), while high merit cows continued to have higher outputs of milk and milk constituents (P<0·001). Body tissue reserves of both genotypes changed little during the grazing period. It is likely that the higher milk yields of the high merit cows can be attributed both to their higher DM intakes and their ability to partition a greater proportion of the nutrients consumed into milk rather than body tissue reserves. Although statistically both high and medium merit cows responded in a similar manner to an increasing proportion of concentrate in the diet, high merit cows did exhibit a 49% greater fat plus protein yield response during the indoor period, compared to animals of medium genetic merit, perhaps hinting at the existence of a genotype×nutrition interaction.

Estimation of Candidate Gene Effects in Dairy Cattle Populations

Standard programs for animal models can be modified to include the effect of a candidate gene, even if only a fraction of the population is genotyped. The elements of the incidence matrix for this effect is 0 or 1 for genotyped individuals and for the probabilities of the candidate gene genotypes for individuals that were not genotyped. The effects of a diallelic candidate gene that were estimated by this method were compared on simulated populations with three alternative estimation methods: analysis of genetic evaluations, yield deviations, and daughter yield deviations, all of which were derived from a standard animal model. The bases of comparison were mean squared error and bias. Four types of experimental designs were considered: genotyping sires only, genotyping cows only, genotyping half of the cows but no sires, and genotyping half of the sires and half of the cows. The estimates that were derived from the three alternative methods all underestimated the simulated effects. The genetic evaluations were more biased than were the yield deviations and the daughter yield deviations. The proposed method was significantly biased only for the design in which half of the daughters, but no sires, were genotyped. Bias and mean squared errors were always lowest by the proposed method.

Marked Effect of β-Lactoglobulin Polymorphism on the Ratio of Casein to Total Protein in Milk

The relationship between genetic variants for milk protein and the composition of milk was analyzed on 4475 repeated milk samples from individual cows; 371 dairy cows of the Swedish Red and White breed and 204 cows of the Swedish Holstein breed were used. The registrations included percentages of casein, protein, fat, and lactose in combination with milk yield and SCC. The genotype of individual cows for αs1-CN, β-CN, κ-CN, and β-LG was determined by alkaline and acidic PAGE. A mixed animal model was used for the analysis; β-LG and aggregate casein genotypes were included simultaneously as separate fixed effects in the statistical model. The results suggest a positive additive effect of the β-LG B allele on casein content and on the ratio of casein to total protein. For the latter trait, the β-LG genotype accounted for a relatively large part of the phenotypic variance, corresponding to a reduction in residual variance of 11% when included in the model. The corresponding value for casein content was 0.5%. The lack of unfavorable associations between milk protein variants and the traits included in this study makes the β-LG gene an obvious candidate when the breeding objective is improved conversion of milk protein into cheese.

Relationships of growth hormone gene and milk protein polymorphisms to milk production traits in Simmental cattle.

The importance of milk proteins and the positive effect of administration of growth hormone (GH) on milk production, and the presence in some dairy cattle lines of greater GH concentrations prompted us to examine the presence of restriction fragment length polymorphism at the GH gene using the restriction enzyme TaqI and to investigate associations between this polymorphism in Simmental cows and bulls, as well as milk protein variants in Simmental cows, and milk production traits. Blood and milk were sampled from 279 Italian Simmental cows and semen was collected from 148 bulls of the same breed. Two fragment bands, denoted A and B, of 6200 and 5200 bp respectively, were examined and three patterns, AA, AB and BB, were found in both animal samples. All variants previously reported in other studies, for kappa, beta, and alpha s1-caseins, and beta-lactoglobulin, were found in the cows' samples. For the cows' samples, a BLUP (Best Linear Unbiased Predictor) analysis of results was performed using a REML (Restricted Maximum Likelihood) program and known heritabilities, whereas for bulls we have performed a General Linear Model analysis. The effect of GH gene polymorphism, using TaqI restriction enzyme, on milk production traits was not significant, but bulls of BB pattern had a higher breeding value for milk yield than AA bulls (P < 0.05). For the kappa-casein genotypic effects, cows of AB genotype gave milk with 1.53 +/- 0.70 g/kg less fat than cows of AA genotype. In addition, breeding values for milk protein content were significantly higher in BB bulls, with 0.87 +/- 0.32 and 0.71 +/- 0.34 g/kg more milk protein than AA and AB bulls respectively. Thus, our results revealed a GH gene polymorphism and indicated significant effects of milk protein polymorphisms on milk production traits in the Italian Simmental breed.

Annual energy intake and early post-partum performance of beef cows differing in body size and milk potential

The energy requirements of beef cows depend on their body size and milk production. Consequently, the optimum cow genotype will depend on the capability of the farming environment to produce forage if undue feeding of purchased supplements is to be avoided. In this study cows of two genotypes with differing genetic potentials for body size and milk production were each offered two levels of annual energy intake.

Annual energy intake and early post-partum performance of beef heifers differing in body size and milk potential

As part of a long term study to assess the suitability of beef cow genotypes, differing in body size and milk potential, for different forage environments within the UK, eight purebred Aberdeen Angus (AA; considered to be small and relatively non-milky) and eight purebred Simmental (Sm; considered to be large and relatively milky) heifers were placed on different levels of annual energy intake. Changes in body composition and milk yield were recorded and related to early post partum ovarian activity.

Annual energy intake and early post-partum performance of beef heifers differing in body size and milk potential

As part of a long term study to assess the suitability of beef cow genotypes, differing in body size and milk potential, for different forage environments within the UK, eight purebred Aberdeen Angus (AA; considered to be small and relatively non-milky) and eight purebred Simmental (Sm; considered to be large and relatively milky) heifers were placed on different levels of annual energy intake. Changes in body composition and milk yield were recorded and related to early post partum ovarian activity.

Implications of genetic changes in body composition on beef production systems

Changing the body composition of beef has implications for the entire beef production system. The dynamic nature of an animal's body composition and the production system itself make predictions of the implications of genetic change in body composition difficult. The cow-calf, stocker, and feeder segments of the production system will be affected differently. Leaner cattle tend to be slaughtered at heavier weights. Heavier weights effectively reduce composition differences of slaughter beef to less than the genetic differences. The effects of four pricing scenarios on slaughter weight and composition were evaluated for two leaner genotypes, one with no change in marbling and one with reduced marbling. A genetic difference of 1.0 yield grade at the same carcass weight resulted in slaughter beef that differed by .4 to 1.0 yield grade because of increased slaughter weights. Separate analyses suggested the stocker segment of beef production will be least affected by changes in body composition. Genotypes that are best fitted to slaughter requirements will have the most flexibility in types of stocker systems that can be used. The cow-calf segment of beef production has several options to adapt to leaner cattle. Management to reduce nutritional stress on leaner cows may be required by some producers. Increased selection for reproductive traits in cow genotypes may be needed. An alternative to selection for reproduction is terminal crossing to partially disassociate the slaughter animals' genotype from the cow's genotype.

The effect of genotype × environment interactions on biological efficiency in beef cows

AbstractAn experiment was conducted to examine the response of three genotypes of beef cows to contrasting levels of nutrition supplied from grazed pasture. Twenty-two Hereford × Friesian (HF), 20 Aberdeen Angus × Friesian (AF) and 24 Welsh Black (WB) spring-calving beef cows with their Charolais-cross calves were used in 4 years consecutively. During the summer grazing period they grazed permanent pasture maintained at either 4 to 5 cm (short) or 7 to 8 cm (tall) sward surface height. Sward height treatment significantly (P &lt; 0·001) affected cow and calf live-weight gain (0·498 v. 0·041 (s.e.d. 0·0405) kg/day and 1·12 v. 0·90 (s.e.d. 0·021) kg/day for cow and calf live-weight gain on the tall and short swards respectively). The live-weight gains of the HF and WB cows were similar, but the AF cows gained less weight on the tall sward and lost weight on the short sward. Calf live-weight gain reflected cow milk yield, with the calves from HF and AF cows having similar live weight gains (1·06 and 1·02 kg/day respectively) and those from WB cows having lower gains (0·95 kg/day; P &lt; 0·001). The effect of sward height on calf live-weight gain was greatest in the WB-born calves because of the lower milk yield from WB cows. Body chemical composition changes of cows were predicted from live weight and body condition score, using prediction equations derived from separate groups of cows which were slaughtered at a range of body compositions for determination of chemical composition. Energy balances, calculated from changes in chemical composition, showed the AF cows to have the lowest energy balances with the WB cows the highest. Calculation of energetic efficiency and land use efficiency of weaned calf production taking account of annual food requirements indicated that the HF cows were most efficient, and the WB cows least efficient. The effect of increasing nutritional environment (as represented by sward height treatment) was such as to increase energetic efficiency for all genotypes, but land use efficiency was increased for HF and AF cows, and decreased for WB cows. These results indicate the factors such as size of cows, milk yield potential and pattern of nutrient partitioning can influence energetic land use efficiency of weaned calf production, and that important interactions between genotype and nutritional environment can occur in different measures of efficiency.

Association of Deficiency of Uridine Monophosphate Synthase with Production and Reproduction

Interaction between genotype at locus for uridine monophosphate synthase and parity was reexamined for 305-d mature equivalent milk and fat production and calving interval. Three lactations for cows of known genotype defined two data files corresponding to different sampling procedures. The first data file selected by herd contained records on 23 cows that were deficient in activity of uridine monophosphate synthase and on 1081 cows with normal activity; the second data file contained records on 19 cows with deficient activity and on 17 cows with normal activity, all daughters of bulls known to be heterozygous at the locus for uridine monophosphate synthase. Results from the mutually exclusive data files were determined independently and then pooled. Genotype and parity interaction, tested against mean square error, was not supported for any of the three traits. Mean differences of the two genotypes, averaged across data files, were, for first, second, and third parities, respectively, 360, 568, and 299kg for milk; 6, 9, and 8kg for fat; and 22, 9, and 12 d for calving interval. Main effect of genotype indicated a 417-kg advantage for heterozygotes but 17-d longer calving interval. The main effect of genotype on milk production adjusted for calving interval was 343kg but was nonsignificant.

New estimates of dry matter intake of lactating beef cows grazing three pasture systems

SUMMARYEstimates of dry matter intake reported by Barlow el al. in this journal in 1988 appeared low for grazing beef cows during early lactation. Further estimates for 144 crossbred and Hereford cows at Grafton, NSW, support the contention that the previous estimates for early lactation were biased downward. This appears to have been simply a scale effect as rankings of pastures and cow genotypes remained unchanged, although the magnitude of differences did alter.

Comparative study on maternal performance of different suckler cow genotypes

Comparative study on maternal performance of different suckler cow genotypes

The effect of energy intake during late pregnancy on the production from two genotypes of suckler cow

ABSTRACTThe effect of energy intake during the final 12 weeks of pregnancy on the production of 59 Blue Grey (Shorthorn × Galloway) (BG) and 56 Hereford × Friesian (HF) cows inseminated with Hereford semen was studied over 2 years.Energy intakes ranged from 34·3 to 78·2 and from 30·3 to 58·2 MJ ME/day for a 500 kg cow in the 2 years respectively. The cows were fed ad libitum for 22 weeks after calving.Plasma 3-hydroxybutyrate concentrations in late pregnancy were closely and inversely related to energy intake.In the first year there was a curvilinear relationship between calf birth weight and pre partum energy intake, maximum birth weights occurring at an intake of about 58 MJ ME/day. Over the lower range of intakes in the second year the relationship was linear and positive; the difference in calf birth weights between extreme levels of intake was 15%.Pre partum energy intake had a small inverse effect on voluntary food intake some 16 to 20 weeks after calving, and a large inverse effect on cow live-weight change throughout lactation, but had no measurable effect on milk production or calf growth rate.HF cows gave birth to heavier calves which grew more quickly in the 2nd year, had higher voluntary food intakes during lactation, and produced more milk than did the BG cows.

Determination Of Quality Of Milk From Different Genotype Of Dairy Cows

The present study was conducted to investigate the milk quality from different genotype. A total 48 dairy cows belong to different genotypes such as Holstein cross, Jersey cross, Sahiwal cross and Red Chittagong were selected. Milk compositional viz. specific gravity, Acidity test, Fat test, Protein test, Solids-not-fat (SNF) test and total solids (TS) test were carried out. It was observed that the higher specific gravity of milk was obtained from Jersey cross and Red Chittagong genotype, which was significantly higher (P&lt;0.01) than the other genotype of dairy cows. The highest acidity (%) was observed (0.165±0.014) in Red Chittagong and the lowest acidity (0.118±0.025) in Sahiwal cross. The highest fat (%) was observed from Red Chittagong cows milk which was statistically higher from Jersey cross and Sahiwal cross and the lowest fat (%) was found in the milk of Holstein cross cows. The highest SNF value was obtained from Jersey cross and the lowest from Sahiwal cross. On the other hand, Holstein cross and Red Chittagong was nearly similar. Red Chittagong milk sample showed the highest TS value and the lowest value was observed from Holstein cross. The highest protein value was found from Red Chittagong and the lowest from Holstein cross but the protein content of other two genotypes were nearly similar. DOI: http://dx.doi.org/10.3329/bjas.v37i1.9868 BJAS 2008; 37(1): 53-56