Department of Animal Science
First Advisor
Richard N. Funston
Second Advisor
James C. MacDonald
Date of this Version
6-15-2019
Citation
Erickson, M.R. 2019. Beef Production Systems in the Nebraska Sandhills. MS Thesis. Univ. of Nebraska, Lincoln.
Abstract
Four studies were conducted to determine the effectiveness of improving production systems of beef cattle in the Sandhills region of Nebraska. These studies were to determine impacts of modified estrus synchronization protocols, genomic testing heifer calves for longevity, and evaluation of 2 differing calving systems (March or May) for improving biological outcome and improved production. Experiment 1 utilized 180 yearling heifers to determine the effectiveness of a second dose of prostaglandin F2α(PGF) with those females not expressing estrus after an initial 14 d MGA-PG estrus synchronization protocol. The treatment of PGF did increase estrus expression, but did not increase the pregnancy success of these females. Experiment 2 utilized 1,518 yearling heifers in a 14 d MGA-PG estrus synchronization protocol. Treatment of 5 μg GnRH was administered 72 h prior to a fixed-time AI (TAI) simultaneous with the typical PGF administration (25mg). The dose of 5 μg GnRH did not increase pregnancy success for initial TAI when compared to the control females. Study 3 genotyped 414 March or May born heifers from the Gudmundsen Sandhills Laboratory from the years 2009-2012. Phenotypic data for each individual was compared to the genomic results from the Igenity Gold panel reported on a 1-10 scale. Regression analysis revealed the birth BW genomic score is a predictor for actual birth BW. The genomic score for calving-ease direct is also a predictor for weaning BW. The iii genomic predictor scores for heifer pregnancy as well as stayability show no significance as predictors for actual heifer pregnancy and female stayability. The final study compared the biological differences when calving in a March versus a May calving season. Data from 3 consecutive years were utilized with 503 cows from the March and 301 from the May systems. Calf birth BW and calf BW at dam’s breeding was greater for May-born calves than March-born. Adjusted weaning BW was greater for March-born. Pregnancy rates, weaning rates, calving interval, calving difficulty, and calf vigor were similar between the systems.
Advisors: Richard N. Funston and James C. MacDonald
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 N. Funston & James C. MacDonald. Lincoln, NE : August 2019
Copyright 2019 McKay Reed Erickson