Department of Animal Science
First Advisor
Rick Funston
Second Advisor
Andrea Cupp
Date of this Version
Summer 7-17-2023
Abstract
Objectives of Experiment 1 was to evaluate the impact of increased energy prior to AI on BW, ADG, and reproductive efficiency in heifers developed on range or in a dry lot. During the winter development period (131 ± 3.5 d/yr) heifers (n= 100/yr) were assigned to either upland range (RANGE) or fed a dry lot diet in two pens that either remained constant (DLLO) or increased in energy prior to AI (DLHI). Heifers developed on RANGE grazed upland winter range until 38 d prior to AI where they then received the DLLO diet. Pre-breeding BW was greater (P £ 0.01) for DLHI and DLLO compared with RANGE but breeding ADG was greater (P £ 0.01) for RANGE compared with DLHI and DLLO. While pregnancy rates to AI were not different (P = 0.34) between DLHI (69%), DLLO (63%), and RANGE (49%), final pregnancy rates tended to be different (P= 0.09) but adjusted p-values did not indicate a significant difference: DLHI (96%), DLLO (95%) and RANGE (84%).
Objectives of Experiments 2 and 3 were to evaluate the impact of methionine supplementation during late gestation on intake, BW, ADG, and subsequent calf performance in primiparous and multiparous females. In Exp 2, 120 randomly selected AI-pregnant heifers were placed in a Calan gate feeding system over 3 yrs (n= 40/yr). Heifers were assigned to 1 of 3 treatments and fed ad libitum hay with either 1) no supplement (CON), 2) 0.9 kg distillers based supplement (DDG), or 3) 0.9 kg distillers based supplement with 30g of a methyl hydroxy analog as MFP (MET). Final BW and ADG, was greater (P < 0.01) in DDG and MET compared to CON heifers. No differences were observed in DMI, or progeny performance. In Exp 3, multiparous cows on upland winter range were fed 1 of 5 treatments: 1) no supplement (NS), 2) ad libitum hay (HAY), 3) 0.45 kg of a distillers based cube (DDG1), 4) 0.9 kg of a distillers based cube (DDG2), or 5) 0.9 kg of a distiller’s based cube plus 30g MFP (MET) during late gestation. No supplement cows had significantly lower BCS scores prior to calving and pre-breeding (P < 0.01). Pregnancy rates for HAY (94%), MET (94%), DDG2 (94%), and DDG1 (95%) were significantly higher (P < 0.01) than NS (81%) cows. There was a tendency (P = 0.09) for calves from HAY cows to have greater marbling compared to NS. While gestational nutrition impacted BW and ADG in primiparous heifers, and BW and BCS in multiparous cows, no differences were seen from methionine supplementation on progeny performance.
Advisors: Rick Funston and Andrea Cupp
Comments
A THESIS Presented to the Faculty of The Graduate College at the University of Nebraska In Partial Fulfillment of Requirements For the Degree of Master of Science, Major: Animal Science, Under the Supervision of Professors Rick Funston and Andrea Cupp. Lincoln, Nebraska: August,2023
Copyright © 2023 Landon Folsom Tadich