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ARS Home » Plains Area » Miles City, Montana » Livestock and Range Research Laboratory » Research » Publications at this Location » Publication #106128
Title: USING GENETIC EVALUATIONS FOR GROWTH AND MATERNAL GAIN FROM BIRTH TO WEANING TO PREDICT ENERGY REQUIREMENTS OF LINE 1 HEREFORD BEEF COWS

Author
item Macneil, Michael
item MOTT, TOM - MAES

Submitted to: Journal of Animal Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/1/2000
Publication Date: 9/1/2000
Citation: MACNEIL, M.D., MOTT, T.B. USING GENETIC EVALUATIONS FOR GROWTH AND MATERNAL GAIN FROM BIRTH TO WEANING TO PREDICT ENERGY REQUIREMENTS OF LINE 1 HEREFORD BEEF COWS. JOURNAL OF ANIMAL SCIENCE. 2000. v. 78. p. 1292-1298.

Interpretive Summary: Beef cattle breeders desire economically focused genetic evaluations. Current systems of genetic evaluation focus almost exclusively on quantities produced with essentially no consideration of costs of production. Maintenance energy required to sustain the cow-herd is a major cost of production. This work proposes a method for combining genetic evaluations for maternal gain from birth to weaning with parameter estimates for a population specific lactation curve. Results can be used as inputs into commonly used predictions of energy requirements. The method presented here allows indirect assessment of the energy required by beef cows to achieve levels of production indicated by their genetic evaluation. It also provides a basis to establish synchrony between genetic evaluation systems and the methods used to predict nutritional requirements.

Technical Abstract: Beef cattle breeders desire economically focused genetic evaluations. Maintenance energy required to sustain the cow-herd is a major cost of production. This work proposes methodology for combining genetic evaluations for maternal gain from birth to weaning with parameters estimates for a population specific lactation curve. The results can be used as inputs into commonly used predictions of energy requirements. Modeling daily milk production (y) as a function of time (t) as y = AT**B exp(-C*T), a kg increase in maternal breeding value for gain from birth to weaning increased the A parameter by 10.8 +_ 4.9% and reduced the B parameter 1.0 +_ .6%. Corresponding estimates of peak milk yield and time of peak lactation are derived from individual animals from their genetic evaluation. Additional inputs for predicting maintenance energy requirements are derived from genetic evaluations for birth weight and mature size. The methodology is demonstrated using genetic evaluations of sires from the Miles City Line 1 Hereford population. Further refinement and application of this methodology may facilitate characterization of beef cattle seedstock for their potential genetic contributions to profitability.