Degree Type

Thesis

Date of Award

2015

Degree Name

Master of Science

Department

Animal Science

First Advisor

Jason W. Ross

Abstract

Reproductive efficiency is crucial to the sustainability of any swine herd. A female’s ability to contribute to the herd earlier, longer, and more proficiently impacts her individual performance characterizing her sow lifetime productivity. Factors that impact a female’s reproductive performance vary from genetic to environmental influencers such as seasonal infertility. Age at puberty onset represents a useful tool to identify sow lifetime productivity. To determine the positive influence of age at puberty onset, physical and physiological measurements taken on a group of gilts were used to identify the potential correlation with a gilt’s age when puberty is achieved. Vulva development after postnatal day 95 and body weight on postnatal day 75 showed to be correlated to a gilt’s ability to achieve puberty earlier or later than their counterparts. While age of puberty onset can increase reproductive performance, environmental factors such as heat stress can negatively impact a female’s reproductive performance. Heat stress is a major contributing factor to seasonal infertility and is associated with decreased farrowing rates, litter performance, and wean-to-estrus intervals. Mitigating the effects of heat stress is key to increasing a female’s reproductive success. To determine how heat stress affects reproductive performance as well as how gilts adapt to stress periods, females that were either tolerant or susceptible to pre-pubertal heat stress were identified, and their response during post-pubertal heat stress periods were evaluated. A gilt’s response to pre-pubertal heat stress has a positive correlation to her response to post-pubertal heat stress. Reproductive measures of fetal weight and crown-rump length were decreased in gilts susceptible to heat stress while corpora lutea diameter was increased in heat stress tolerant gilts when exposed to heat stress during breeding.

Copyright Owner

Kody Lane Graves

Language

en

File Format

application/pdf

File Size

132 pages

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