Improved Technologies for Assessing Semen

Quality and Boar Fertility

¹George Foxcroft, ¹Xiaoji Xu, ²Serge Pommier, ²Todor Arbov, ²Bill Hutchings and ²William Sotto

¹Alberta Pork Research Centre, Department of Agricultural, Food & Nutritional Science, University of Alberta, Edmonton, AB, Canada, T6G 2P5

² Pig Improvement (Canada) Ltd, P.O. Box 266, Acme, AB, Canada, T0M 0A0

On three occasions at the start, in the middle, and at the end of a 20-week period of breeding, special fractionated collections of the whole ejaculate were carried out using established procedures to provide a semen sample from the first sperm-rich part of the ejaculate from 6 boars. These samples were immediately transported to the in vitro laboratory at the University of Alberta. After standard maturation procedures, three different dilutions of the semen sample were used in a standardized in vitro fertilization (IVF) test on oocytes recovered from prepubertal slaughterhouse ovaries and also matured in vitro. This in vitro evaluation provides data on the ability of the sperm to penetrate and fertilize the egg. At the time of collection, routine assessments of the motility, concentration and normal morphology of the semen sample were also carried out by staff in Acme, and motility assessments were repeated on d5 and d7 after collection.

All other collections during the 20-week period were processed according to normal commercial practice using the AndroHEP extender and semen from the same ejaculate was used to inseminate equal numbers of recently weaned sows with a dose of either 3 or 2.5 billion total sperm. Sows were inseminated three times during the estrus period. Data from dose-matched breedings were obtained for a total of 444 sows, with between 12 and 54 sows bred with each semen dose across the six boars. Analytical techniques were used to determine the overall effect of semen dose on farrowing rate and litter size born: associations among the different laboratory and in vitro estimates of semen quality, and the breeding results obtained, were established across and within boars.

All in vitro measures of sperm function were significantly different among boars and use of different semen dilutions for IVF allowed further discrimination of apparent sperm quality among boars. The standard laboratory evaluation on the same semen samples also indicated significant effects of boar on total sperm numbers, day 0 motility and the percentage of abnormal sperm. Sperm dose used for AI had no effect on farrowing rate ((80.7 and 81.5%) but the lower AI dose resulted in a reduction (P<0.045) in total numbers born (10.1 v 10.8). Sperm normality on day 0, as well as several in vitro measures of sperm function, explained a large part of the variance in litter size born.

Implication: These results indicate that morphological characteristics are a useful measure of semen quality using existing procedures for semen evaluation. In vitro estimates of sperm function also show promise for estimating semen quality and these technologies need wider evaluation.