Date of Award

5-2018

Document Type

Thesis

Degree Name

Master of Science (MS)

Department

Animal and Veterinary Sciences

Committee Member

Dr. Nathan M. Long, Committee Chair

Committee Member

Dr. Scott L. Pratt

Committee Member

Dr. Gary M. Hill

Abstract

Late gestation and post-weaning are two critical periods a calf needs to receive proper nutrition to insure adequate growth for the rest of the animal’s lifespan. Supplementation at these critical time points may be necessary in order to meet nutritional requirements. The objectives of this research were to 1) assess the performance and endocrine regulation of 15 mo old heifers born to dams who were nutrient restricted with or without protein supplementation during the last 100 d of gestation (NRS and NR, respectively) and 2) determine the effects of weaning age, lipid supplementation, and days on lipid supplement on growth, circulating metabolites, and marbling in young steers. In the first study, dams producing heifer calves were either fed to meet requirements (CON), fed to reduced BCS by 1.2 (NR) or fed to reduce BCS by 1.2 and supplemented with protein 3 d/wk (NRS). At 15 mo of age, heifer offspring were subjected to a 10 wk feeding trial in which blood samples and BW were collected bi-weekly. At the end of feeding, 21 randomly subsampled heifers were subjected to an intravenous glucose tolerance test (IVGTT). Heifers born to NR dams experienced altered appetite and endocrine regulation compared with heifers born to CON dams. This study indicated that protein supplementation in dams experiencing NR during the last 100 d of gestation may abate the negative effects associated with DMI and glucose regulation because NR heifers experienced increased DMI and signs of insulin resistance whereas NRS heifers exhibited DMI and glucose regulation similar to that of CON heifers. In the second study, steers were either early-weaned 150 ± 11 d of age (EW) or traditionally weaned at 210 ± 11 d of age (TW) and assigned to either a rumen-bypass lipid treatment (RBL) or an isocaloric, isonitrogenous corn gluten feed treatment ration (CGF). Within each treatment, steers were fed for a duration of either 45 or 90 d. Body weight and blood samples were collected on d 0, 22, 45, 66, and 90. Following the end of treatment steers were harvested at a commercial processing plant where carcass measurements were obtained. Steaks from each animal were used for proximate analysis. Circulating metabolites, marbling content, and specific as well as total fatty acid concentrations were increased in RBL steers compared to CGF steers. Overall, our results indicate that supplementation during late gestation and at weaning improves animal performance and could improve the efficiency of production.

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