Animal Science Department

 

Date of this Version

12-2011

Comments

A DISSERTATION Presented to the Faculty of The Graduate College at the University of Nebraska In Partial Fulfillment of Requirements For the Degree Doctor of Philosophy, Major: Animal Science, Under the Supervision of Professors Terry J. Klopfenstein and L. Aaron Stalker. Lincoln, Nebraska: December, 2011

Copyright (c) 2011 Kelsey M. Rolfe

Abstract

A 3-yr study evaluated effects of supplementing modified wet distillers grains with solubles during summer grazing and subsequent feedlot sorting on long yearling steers. During summer grazing, supplemented steers had greater ADG and were more profitable than non-supplemented steers. At feedlot entry, supplemented steers were 48 kg heavier than non-supplemented steers. Feed efficiency and DMI were not different between supplementation treatments during finishing. Supplemented steers were fed 24 fewer days to reach a similar 12th rib fat thickness, had greater LM area, and lower marbling compared to non-supplemented steers. Overall profitability favored supplementing steers because less expensive summer gains also reduced feedlot inputs. Sorting on feedlot entry BW increased HCW, marbling, and YG. However, percentage overweight carcasses and profitability were similar between the sort treatments.

An ongoing 3-yr trial was conducted to elucidate effects of weaning date and pre-partum nutrition on cow-calf productivity in a spring calving system. The first 2-yr of data found dams weaned in October weaned cows grazing winter range had greater BCS and BW compared to December weaned cows pre-calving. Dams on a higher nutritional plane from winter grazing treatment had greater BCS and BW prior to parturition and breeding. However, subsequent pregnancy rates for cows were similar among weaning and winter grazing treatments. Calves born to dams on a higher nutritional plane had greater adjusted weaning BW. There were no differences in percentage cycling prior to breeding or pregnancy rate of heifer progeny. Steer progeny born to dams receiving supplement or wintered on corn residue had greater 12th rib fat thickness at harvest. Net change in return was greatest when October weaned dams were wintered on corn residue and December weaned dams were on winter range with 0.91 kg supplement if calves were sold at weaning. When ownership was retained, steer progeny born to dams on corn residue during winter grazing resulted in the greatest net change in return.

Advisors: Terry J. Klopfenstein and L. Aaron Stalker

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