Date of Award

2024

Document Type

Master Thesis

Degree Name

Masters of Science (Research)

Department

BIOLOGICAL SCIENCES

First Advisor

Prof Roy D. Sleator

Second Advisor

Prof Donagh P. Berry

Abstract

The thesis served to quantify the phenotypic performance of animals differing in genetic merit based on the Irish Terminal Breeding Index. The data in the thesis included performance metrics of interest to both the primary producer and the meat processing industry. It is anticipated that the findings of the thesis will instil a level of confidence among primary producers and meat processors whereby the current terminal breeding objective is generating beef cattle with superior carcass performance, and improved farm margins along with a more desirable animal for meat processors. The impact of genetic differences among animals for performance traits on subsequent phenotypic performance is well documented, albeit limited in terms of population size and diversity in production systems represented. Studies that comprise larger datasets to quantify the association between animal genetic merit and phenotypic performance are confined to comparison of parameters contributing to performance traits within the farm gate only. Some studies, albeit limited, have attempted to quantify the value of genetic selection in cattle to downstream sectors of the beef industry, particularly the meat processing sector. To address the gap in the literature, the current thesis serves to quantify the phenotypic performance of animals differing in genetic merit based on the Irish Terminal Breeding Index. The objective of the first study was to quantify if differences among animals in genetic merit materialised into phenotypic differences in commercial herds. Carcass phenotypic information was available on 156,864 animals from 7,301 finishing herds. A terminal index for each animal was calculated based on the pedigree index for calving performance, feed intake, and carcass traits. The association between terminal index and phenotypic performance at slaughter was undertaken using mixed models; if the association differed by gender (i.e., young bulls, steers, and heifers) or by early life experiences (animals born in a dairy herd or beef herd) was also investigated. The objective of the second study was to characterize detailed carcass attributes of animals divergent in genetic merit for a terminal index as well as individual measures of genetic merit for carcass weight, conformation and fat. The data used consisted of 53,674 young bulls and steers slaughtered between the years 2010 and 2013 in multiple Irish processing plants. Results of these studies highlight the importance of breeding programmes for terminal characteristics for both the meat processors, the producer and the entire food production chain, while at the same time playing a key role in meeting greenhouse gas emission reduction targets set for the agricultural sectors

Access Level

info:eu-repo/semantics/openAccess

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