Production Traits In Dairy Cattle Research Articles

A Further Look at Evidence for Cytoplasmic Inheritance of Production Traits in Dairy Cattle

A recent study interpreted significant effects of source of cytoplasm as evidence for cytoplasmic inheritance. An alternative interpretation that observed results reflected residual additive genetic effects unaccounted for by statistical models used was tested by computer simulation of records over 60 yr for milk yield (h2=.30) and fat percentage (h2=.60) under an additive genetic model with no cytoplasmic effects. First lactation records for the last 30 yr were analyzed by least squares according to models that included effects of cytoplasmic source, generations to cytoplasmic source, herd, and year as well as effects of sire (model 1), sire and record of dam (model 2), Predicted Difference of sire (model 3), or Predicted Difference of sire and ½ Predicted Difference of maternal grandsire (model 4). Ten replicates were performed. Significant cytoplasmic effects were observed for all models in at least 8 of 10 replicates for milk yield and in all replicates for fat percentage. Average F ratios for cytoplasmic effects were 1.43, 1.25, 1.46, and 1.43 for milk yield and 2.00, 1.29, 2.04, and 1.96 for fat percentage for models 1, 2, 3, and 4. Cytoplasmic variances were 1.4 and 3.2% of residual variances for milk yield and fat percentage for model 1. Unaccounted for additive genetic effects can produce spurious cytoplasmic effects.

Effects of Cytoplasmic Inheritance on Production Traits of Dairy Cattle

Pedigrees of 4461 cows were traced to the original female in a maternal line. Cytoplasmic origin was defined as the first female in the maternal lineage. There were 102 cytoplasmic lines. Most cows were at least 10 generations removed from the origin. After adjustment for sire, herd, calving year, calving month, and age, cytoplasmic effects accounted for 2.0, 1.8, 1.8, and 3.5% of total variation of milk yield, milk fat yield, 3.7% fat-corrected milk yield, and milk fat percentage in first lactation. Cytoplasmic effects were also in models that included adjustments for sires, maternal grandsires, and dam's production. Correlations among independent subsets agreed with expectations. Cytoplasmic origin was a significant source of variation of production traits of dairy cattle.

Review of rapeseed meal in animal nutrition: Ruminant animals

AbstractDuring recent years, world literature in this area has increasingly dealt with the assessment of low glucosinolate RSM‐type (LGRSM). Generally, the LGRSM‐types show clear advantages over the high glucosinolate RSM‐types (HGRSM). Acceptibility of concentrates to dairy cattle may be influenced negatively by increasing RSM of commercial Canadian HG‐type beyond 15%. LGRSM seems to be acceptable up to at least 20% of the concentrate mixture. LGRSM‐type meal of cv. Candle may possibly still be accepted at higher levels. There are indications of a higher nutritive value of the LG vs the HGRSM types. Candle has been found to be as good as, if not better than, Tower RSM. HGRSM of European origin at a level of 15–20% of the concentrate seems to decrease milk production and to influence milk composition negatively. Canadian‐type LGRSM feeding at a level of 25% of the concentrate does not seem to be harmful to dairy cattle. Inclusion of 34% LGRSM lowered feed intake and milk yield. Higher milk yields are indicated when Candle is included, in comparison to Tower. Only a limited influence on milk composition (protein, fat, solids—nonfat) has been reported to result from RSM‐feeding. Both HG‐ and LGRSM increase milk SCN− and decrease milk‐I contents, the milk‐I, however, to a minor extent. A minute part of the OZT has been found to be carried over into milk resulting in levels much below the safe level for human consumption. Inclusion of “gums” at levels up to several times the amount corresponding to normal production has not been found to impair production traits of dairy cattle or growing cattle. Microbiological degradation of RSM in the rumen can be minimized by formaldehyde treatment, which has been reported to increase milk production. Rapeseed and rapeseed expeller seem to be prospective fat and protein sources to dairy cattle, especially in rations low in crude fat (<15 g dig. fat/kg milk). The inclusion of these products increases blood cholesterol and plasma glycerides. The iodine number of milk fat is increased.

Blood and Milk Protein Polymorphisms in Relation to Feed Efficiency and Production Traits of Dairy Cattle

The relationship was studied between 14 biochemical polymorphisms, including 9 blood antigens, serum transferrin, and 4 milk protein systems, and 8 quantitative traits consisting of measures of milk composition, feed efficiency, and consumption of dry matter. Data from 184 Holstein cows fed experimentally during their first lactation were over 10 year-seasons from 14 sire groups on 4 different rations. In all cases, ration differences were large (P<.01). Sire differences were next most important and nearly all significant (P<.05). Season was relatively unimportant as a cause of variation in feed efficiency but showed significant differences (P<.05) in most other traits. A difference in dry matter consumption of 163kg between F antigen genotypes and 193kg between M genotypes was significant (P<.05). Differences in feed efficiency up to 3.4% for S antigen genotypes and up to 2.4% for Lg genotypes were significant (P<.05). Analysis with dry matter consumption as a covariate revealed significant genotype differences (P<.05) of up to 542kg milk, 43kg solids-not-fat, 58kg total solids, 45kg fat-corrected milk yield and 2.4% efficiency for the Lg system. Squared coefficients of correlation revealed a contribution of genotype from 0 to 4.9% of the variation in traits.

Sire by Region Interaction for Production Traits in Dairy Cattle

During the past decade considerable attention has been given to sire by herd interactions, but data have not been available to consider the broader regional aspects of this problem. Sire by region interactions for milk production, fat production, and fat test were examined, utilizing the first available DHIA record of 10,548 artificially sired daughters of 46 Holstein sires used in the northern and southern regions of the United States. Daughter records were expressed as deviations from adjusted herd-mate averages. Correlations between the average breeding values of the sires in the two regions for the three traits approached 1.00, indicating that the ranking of sires was essentially the same in both regions. Estimates of the sire by region interaction variances for the three traits also were essentially zero. Although additional confirmation is needed, these results suggest that influences associated with a particular region should not unduly confuse the ranking of sires in the different regions when herd-mate comparisons from artificially sired daughters are used.

Effects of Mating System on Production Traits in Dairy Cattle

An experiment designed to study the effect of various mating systems on sire-lines of dairy cattle is described. Inbreeding depressions were found in various production traits by comparing outbreds with inbreds (F, ≅ 0.25). The differences were 1,313lb, 35lb, 1,761lb, and 48lb in favor of the former, in actual milk, actual fat, M.E. milk, and M.E. fat. of the first lactation, respectively. For the same traits, differences of 1,832lb, 74lb, 2,455lb, and 97lb, respectively, were found in favor of the two-line crosses compared to inbreds of the same line. However, inbreeding effects varied significantly among sire-lines. There was no evidence that increase of production with age was more rapid in inbreds than in outbreds.

Variation in performance of European dairy cattle in Ceylon

The existence of a high degree of variability in all production traits of dairy cattle in tropical countries has been demonstrated. Evidence has been adduced to show that this is due largely to increased environmental variability than to any great inherent differences between animals. The conclusion is drawn that, despite minor differences, the genetics of milk production in tropical dairy cattle is fundamentally very similar to that in European stock.

Sire by Herd Interaction in Production Traits in Dairy Cattle

Sire by Herd Interaction in Production Traits in Dairy Cattle

Influence of rearing intensity on body development and milk production

The ingenious biochemical system, which we generally call heredity, directs the body development and regulates the reaction of the individual in relation to the environmental conditions. It is this genetically determined adaptiveness of the individual which makes it possible for organic life to survive even when the climatic conditions and the supply of nutriment vary within wide limits in nature.The interaction of heredity and environment involves several problems of vital importance for animal production. One such problem is the influence of level of nutrition during the rearing period on body development, fertility, milk production and longevity. When investigating the relative importance of heredity and various environmental factors on the production traits in dairy cattle, we have concentrated much of our effort on this special problem.