Location: Livestock and Range Research Laboratory2015 Annual Report
1: Determine the impact of the level of harvested feed input on the sustainability of beef production systems, including annual reproductive success, lifetime productivity, and progeny performance. 2: Evaluate use of dormant, animal-harvested forages as a substitute for mechanically harvested feeds in developing replacement heifers. 3: Develop new and better genetic and physiological indicators of fertility in yearling bulls and beef cows to enhance annual and life-cycle reproductive success. 4: Assess locus-specific genetic effects attributable to heterozygosity on reproductive success and productivity in production systems making differential use of native range forages. 5. Improve breeding and management decisions by characterizing current genetic and phenotypic variation within and between predominant beef breeds and crosses using novel genomic and genetic evaluation technologies and identify novel genomic variants to optimize forage based production efficiencies for beef cattle within and across diverse physical environments in the US Great Plains.
Feed consumption and replacement of cows, culled for reproductive failure, are two primary determinants of beef production efficiency. Our overarching goal is to develop strategies and technologies to alleviate these limitations. Sufficient nutrient intake resulting in adequate body energy stores are believed essential for reproduction. Thus, producers are challenged to match nutritional environment, which is subject to seasonal and annual variation, and various genotypes to obtain sustainable reproduction and retention rates. Our approach is, of necessity, long-term and multi-disciplinary, involving both basic and applied aspects of genetics, nutrition, and physiology in a semi-arid grazing production system. This proposal brings to fruition ongoing research and establishes investigations of genetic by environmental interactions and physiological mechanisms limiting reproductive success. Four distinct cattle populations (an intercross of Charolais (25%), Red Angus (50%) and Tarentaise (25%), Line 1 Hereford, purebred Angus, and Hereford-Angus herd) will be used to facilitate assessment of genetic factors affecting fitness (hybrid vigor). Distinct nutritional environments that utilize different contributions of harvested and grazed forage will be imposed to challenge the nutrition-reproduction interface to elucidate genetic, physiological, and management factors influencing feed utilization and lifetime productivity. Identification of genetic, nutritional, and physiological mechanisms that limit or contribute to beef production efficiency will facilitate early in life selection and management of replacement animals most fit for particular production environments. This research will result in the establishment of heifer development protocols that provide producers options for dealing with annual variations in availability and quality of forage.
1. Phenotypic and genotypic data continue to be collected to assess the impact of the level of harvested feed input on the sustainability of beef production systems, including annual reproductive success, lifetime productivity, and progeny performance. Data have been analyzed to determine the effects that level of harvested feed provided to the individual animal and its dam have on herd retention. These accomplishments build the mass of critical data needed to evaluate economic and biological impacts harvested feed inputs may or may not elicit in promoting high lifetime productivity. 2. Heifer calves born in 2014 were subjected to experimental treatments (fenceline weaned and pasture developed vs. feedlot weaning and development). Methodology was established to measure supplemental feed intake, heart rate and activity in individual animals in pasture setting. Assessment of resting heart rate and activity were successfully determined in 63 range heifers at 6 periods during the year. 3. Animal sample collection is complete with tissue, serum and DNA analysis for determination of new and better genetic and physiological indicators of fertility. Analysis of data has followed and preliminary analysis suggest the are specific genes associated with high and low fertility. 4. Purchased and reared Angus females have been added to the herd. Data on feed intake, postweaning development traits and fertility were collected along with DNA and SNP data. First year of F1 progeny are on the ground leading to the first opportunities to collect both phenotypic and genotypic data.
Waterman, R.C., Sawyer, J.E., Kane, K.K., Hawkins, D.E., Petersen, M.K. 2014. Heifer body weight gain and reproductive achievement in response to protein and energy supplementation while grazing dormant range forage. Agricultural Sciences. 5:1296-1304.
Swartz, J.D., Lachman, M., Westveer, K., O'Neill, T., Geary, T.W., Kott, R.W., Berardinelli, J.G., Hatfield, P.G., Thomson, J.M., Roberts, A.J., Yeoman, C.J. 2014. Characterization of the vaginal microbiota of ewes and cows reveals a unique microbiota with low levels of lactobacilli and near-neutral pH. Frontiers in Veterinary Infectious Diseases. 1(19):1-10.
Roberts, A.J., Petersen, M.K., Funston, R.N. 2015. Can we build the cowherd by increasing longevity of females? Journal of Animal Science. 93:4235-4243.