Animal Science, Department of
Department of Animal Science: Dissertations, Theses, and Student Research
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First Advisor
Richard N. Funston
Committee Members
Matt C. Stockton, James C. MacDonald
Date of this Version
8-2019
Document Type
Thesis
Citation
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 Professor Richard N. Funston
Lincoln, Nebraska, August 2019
Abstract
The objectives of this research were to 1) evaluate the effects of late gestation supplementation, synchronization and creep feeding on cow and calf production traits 2) evaluate the pooled effects of 5 studies involving late gestation supplementation on cow and calf traits. Experiment 1 was a three year study conducted on 8 pastures at the Gudmundsen Sandhills Laboratory. Cows were assigned to 1 of 4 late-gestation supplementation treatments, postpartum progestin or control, and 1 of 2 creep feed treatments to make up a 4 x 2 x 2 factorial arrangement. Calves were followed through to slaughter.
Experiment 2 involved 5 studies all conducted at the UNL Gudmundsen Sandhills Laboratory. Studies were pooled based on similar treatments of late gestation supplementation on dormant upland pasture or meadow and different weaning periods. Cow and calf data was analyzed for various traits.
Within Experiment 1 all three levels of supplementation increased cow BW and BCS, while the non-supplemented decreased in both. Supplementation treatments did not affect reproductive efficiency such as calving date, calving rate, weaning rate or pregnancy rate. Synchronization had similar results as there were no effects on reproductive measures or calf BW. Supplementation to cows had no effect on calf production traits through slaughter. Creep feeding calves significantly increased calf BW at weaning, yield grade and 12th rib fat. However on a cost/ benefit analysis creep feeding under these conditions added no value on profitability.
Different results were achieved with the larger data set of late gestation supplementation. The pooled analysis demonstrated significant effects from supplementation on cow pregnancy rate, adjusted calf BW at weaning but no effect on carcass characteristics. March systems had a higher average pair feed cost but lower cow replacement cost compared to May. The March calving system had higher average net returns based on 9 yrs of market data compared to a May calving system. These studies indicate the effect and importance of late gestation supplementation on cow and calf productivity in a spring calving herd. Cow-calf producers should carefully consider calving system utilization based on their unique production goals.
Advisor: Richard N. Funston
Comments
Copyright © 2019, Devin Lynn Broadhead. Used by permission