2008 Annual Report
Objective 2: Determine breed and within-breed genetic effects on feed efficiency, growth, and fertility of cattle.
Sub-objective 2.A. Determine breed and within-breed genetic effects on nutrient utilization.
Sub-objective 2.B. Determine breed and within-breed genetic effects on reproductive efficiency.
Objective 3: Discover QTL and estimate genomic effects for traits contributing to differences in efficiency among cattle.
Objective 4: Fine map identified QTL for reproductive rate in cattle.
Objective 5: Enhance existing simulation models to investigate genetic-by-environmental interactions on beef life-cycle efficiency and integrate into decision support software.
Objective 6: Identify nutritional effects on expression of genes and subsequent phenotypes, and integrate this information with our current understanding of physiology to enhance management decisions.
Research in this project is being undertaken to study genetic and environmental factors that lead to variation in efficiency in beef production. This project addresses measures of efficiency at different phases of the production system to identify those factors that have additive merit and antagonistic relationships across the different phases of production. The initial component of the project is to develop facilities and methodologies to efficiently collect economically and biologically important phenotypic data relevant to efficiency. After developing capabilities to measure the phenotypes, the contribution of genetics and environment/management to variation in efficiency of production will be determined. Genetic variation will be evaluated using both quantitative genetics and QTL discovery. Information gained from both the genetic and environmental studies will be used to parameterize simulation models that provide decision support software to allow producers to simulate potential outcomes to optimize production efficiency when different combinations of animal genetics and management strategies are used.
Providing supplemental feed to pregnant cows when grazed forages are not available is costly. Research conducted at the U.S. Meat Animal Research Center found that the efficiency of energy gain during late pregnancy was high which would allow for the development of management strategies that increase the use of grazed forages and/or alter the time that supplemental feed is fed. These results demonstrate how energy stored in the body of the cow can be used as part of a total feed management plan. This research addresses National Program Action Plan Component 2 “Enhancing animal adaptation, well-being, and efficiency in diverse production systems” and addresses National Program Action Plan Problem Statement 2C “Conversion to animal products.”2. Calves born to cows bred increases in cows selected for increased ovulation rate, but increases above twin births may be reduced due to increased embryo and fetal mortality resulting from crowding in the uterus.
The limitation of one calf per year limits the production potential of beef cattle. Research conducted at the U.S. Meat Animal Research Center found that selecting for increased ovulation rate can be used to increase the number of calves within a pregnancy thus increasing the annual production potential of a cow. However, capacity of the uterus to successfully support the growth of more than two calves may be limiting suggesting the need to include uterine capacity in a selection index for increased birth rate. These findings demonstrate that selection for increased birth rate in beef cattle can be used as a tool for developing cattle with higher production potential. This research addresses National Program Action Plan Component 2 “Enhancing animal adaptation, well-being, and efficiency in diverse production systems” and addresses National Program Action Plan Problem Statement 2B “Reducing reproductive losses.”3. Amino acid availability increases when moderate quality forage is supplemented with dried distiller’s grains with solubles.
Forage protein quality varies with locale and season and at times is not adequate to support the desired production level of grazing ruminants. Research conducted at the U.S. Meat Animal Research Center found that supplementation of grass hay with distiller’s grains compared to corn increased amino acid absorption. These findings suggest that dried distiller’s grains are a potential feed resource for supplementing low protein forages. This research addresses National Program Action Plan Component 2 “Enhancing animal adaptation, well-being, and efficiency in diverse production systems” and addresses National Program Action Plan Problem Statement 2C “Conversion to animal products.”
5.Significant Activities that Support Special Target Populations
Archibeque, S.L., Freetly, H.C., Ferrell, C.L. 2008. Feeding distillers grains supplements to improve amino acid nutriture of lambs consuming moderate-quality forages. Journal of Animal Science. 86(3):691-701.
Freetly, H.C., Nienaber, J.A., Brown Brandl, T.M. 2008. Partitioning of energy in pregnant beef cows during nutritionally induced weight fluctuation. Journal of Animal Science. 86(2):370-377.
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(9):2156-2162.
Thallman, R.M., Kuehn, L.A., Allan, M.F., Bennett, G.L., Koohmaraie, M. 2008. Opportunities for collaborative phenotyping for disease resistance traits in a large beef cattle resource population. Developments in Biologicals. 132:327-330.
Echternkamp, S.E., Cushman, R.A., Allan, M.F., Thallman, R.M., Gregory, K.E. 2007. Effects of ovulation rate and fetal number on fertility in twin-producing cattle. Journal of Animal Science. 85(12):3228-3238.
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(12):3239-3248.