Effects of sow, boar, and semen traits on sow reproduction

Authors

Sungwon Park, University of Nebraska-LincolnFollow

Date of this Version

Spring 2013

Comments

A THESIS Presented to the Faculty of The Graduate College of the University of Nebraska In Partial Fulfillment of Requirements For the Degree of Master of Science, Major: Animal Science, Under the Supervision of Professor Rodger K. Johnson. Lincoln, Nebraska: May, 2013

Copyright (c) 2013 Sungwon Park

Abstract

The objective was to estimate the effect of traits recorded in females and in boars and their semen on farrowing rate (FR), total number (TB) and number of stillborn pigs (SB) at birth. Results of 20,569 inseminations in 4,468 sows on 4 farms with semen from 856 boars in 2 AI centers were analyzed. Records on sows included farm, dline parity and brdeeding interval (Brdint). Records on boars included number of days rest between collections, and 26 characteristics (e.g., volume, sperm concentration, motility, abnormal heads and tails plus 16 traits that described velocity and path of sperm cell movement). At first time, we were trying to use whole boar semen traits for our analysis; however the attempt was not competitive enough to reveal which semen characteristics had been far more deeply involved in FR, TB and SB. Thus, we used STEPWISE, MAXR and R-square were used for choosing statistically best semen characteristics. Data were analyzed with SAS PROC MIXED in models accounting for fixed effects of farm dam line of sow (Dline) and parity, random effects of sow and boar, and regressions of sow reproductive traits on sow, boar, and semen traits. Models were first fitted with only linear regressions; if important (P < 0.10), 2^nd models including quadratic effects were fitted. Parity and the interval from 1^st insemination (1^st estrous during breeding period in gilts, and 1^st post-weaning estrus in sows) to the insemination that resulted in a litter affected (P < 0.01) FR, and SB (P<0.1); parity also affected FR, TB and SB (P < 0.01). Average FR declined in a quadratic manner by 0.15 as the interval from 1^st insemination to insemination of conception increased from 0 to 65 days. Sow reproductive traits were not affected (P>0.10) by number of days between collections (all boars had at least 3 d rest) or sperm concentration. Ten traits (Tmot, Vol, Proximal, Distal, Compos, Head, Tail, VAP, DSL and AOC) describing semen traits affected sow reproduction (P < 0.10), but differences across the range of variation were relatively small.

Advisor: Rodger K. Johnson