Submitted to: American Society of Animal Science Southern Section Meeting
Publication Type: Abstract Only
Publication Acceptance Date: 2/3/2004
Publication Date: 2/14/2004
Citation: Brown, M.A., Coleman, S.W., Lalman, D.L. 2004. Relationship of sire estimated progeny differences in milk yield in Brangus cows [abstract]. American Society of Animal Science Southern Section Meeting. Paper No. 20. Interpretive Summary: ABSTRACT ONLY
Technical Abstract: Milk yield from 160 Brangus cows sired by 65 Brangus bulls was measured over a period of three years using a single-cow milking machine to estimate the relationship of sire estimated progeny differences for milk with actual milk yield of their daughters and calf weights during the preweaning period. Milk yield was estimated six times per year at an average 49, 78, 109, 138, 168, and 198 d postpartum. The relationship of sire milk EPD to milk yield of their daughters was quadratic (P < 0.01) and the linear portion of the curve differed among months (P < 0.05) at an average cow weight. However, the relationship was largely linear in cows weighing 500 kg or less and curvilinear in cows weighing more than 500 kg. Similarly, the regression of average daily milk yield and total 205-d milk yield were curvilinear (P < 0.10). The relationship of grandsire milk EPD to calf weight was quadratic (P < 0.01) with a trend for the quadratic portion of the curve to differ with month of lactation (P = 0.15) and evidence for monthly differences in the linear component of the equation (P < 0.01). A trend existed for the relationship of grandsire milk EPD with calf 205-d weight to be curvilinear (P < 0.19). However, the relationship of calf 205-d weight to milk yield of their dam was linear (P < 0.01). Results from these data suggest that genetic potential for milk yield and associated effects on calf weight transmitted through the sire may have a practical maximum due to nutritional limitations that prevent expression of genetic potential beyond that level, particularly in heavier cows. Thus, there is a need to match both genetic potential for mature weight and genetic potential for milk yield and calf weaning weight with specific production environments.