This project examined the feasibility of producing USDA Choice beef—without grain-based finishing—through genetic selection and pasture management. Purebred Angus heifers with high-marbling potential and small/medium frame size were born spring 2011. Heifers were allotted to either pasture (grass-finishing) or feedlot (grain-fed) treatments based on liveweight and intramuscular fat content. When reaching market weight (±1,000 lb) heifers were harvested and carcass data was collected. Feedlot cattle were marketed on August 27, 2012. The grass-finished cattle were marketed on November 1, 2012. Starting and end weights were similar for both treatments but feedlot cattle reached market weight 50% faster (3.9 vs 2.1 lb/day). The average intramuscular fat percent was not different at the start of the trial but there was a trend of grain-fed cattle to have greater intramuscular fat. Rib eye area, yield grade, and number grading Choice were numerically higher for feedlot cattle. This project demonstrated that it is feasible to combine high marbling genetics with pasture management to produce Choice beef in Iowa. Grass-finished cattle were able to achieve 2.1 pounds of gain per day and 60% of the grass-finished cattle ultimately graded Choice. Selection of small-framed, high-marbling potential beef cattle is essential because of the relatively low-energy density of the grass-based diet and the limited grazing season. Efforts to improve pasture quality and extend the grazing season would be beneficial to meet this goal.

Host genetic differences in viral load (VL) and weight gain (WG) during challenge were assessed for five trials of ~200 commercial crossbred piglets each, all from different commercial suppliers. Piglets were experimentally infected with porcine reproductive and respiratory syndrome virus (PRRSV) isolate KS-2006-72109 in order to validate the effects of a SNP previously identified on SSC4 (WUR10000125), whereby AB individuals had increased WG and reduced VL when experimentally infected with PRRSV isolate NVSL-97-7895. VL was defined as the area under the curve of logged viremia from 0-21 dpi. WG was defined as the weight gained from 0-42 dpi. The SNP effects on VL and WG were assessed. AB individuals had higher WG and lower VL than AA individuals, suggesting this marker may be useful for genetic selection of pigs for increased resistance or reduced susceptibility to PRRSV isolates that differ genetically and possibly pathogenically.

Dry matter intake, milk production, and milk production efficiency were evaluated in 84 Holstein dairy cows fed either a control diet or a control diet plus the direct-fed microbial Bovamine. Neither milk nor ECM production were affected by feeding Bovamine. Feeding Bovamine, however, decreased DMI by 3.59%, resulting in an improvement in milk production efficiency and ECM production efficiency of 6.1% and 5.3%, respectively. Inclusion of Bovamine in dairy cattle diets should be considered to increase milk production efficiency.

Genomic prediction involves using high-density marker genotypes to characterize the impact on performance of every region of the genome, and using that information to predict performance of genotyped selection candidates. This is a relatively new technology and is now gaining traction in personalized medicine and in various livestock industries. Our new approach promises to overcome serious limitations with existing techniques for genomic prediction.

Recent, new instructorship of the senior-level beef systems management course (An S 426) presented the opportunity to conduct a thorough evaluation and potential revision of the course curriculum. The objective of this study was to conduct a structured, critical evaluation of the course using a modified Delphi method, and utilize the results to update course objectives and student outcomes. Based on stakeholder feedback, the course is implementing heightened emphases on business and financial planning in addition to the basic managerial principals in the beef production process.