BOAR, BREED AND ENVIRONMENTAL FACTORS INFLUENCING SEMEN CHARACTERISTICS OF BOARS USED IN ARTIFICIAL INSEMINATION

Abstract

A total of 12 717 ejaculates from 74 Yorkshire, 25 Hampshire, 35 Duroc, 27 Landrace and 5 Lacombe boars were measured for semen volume, sperm concentration, percentage live sperm, motility and potential doses of semen. The data were collected by the Ontario Swine AI Association between 1971 and 1980. Boar repeatability and the effects of breed of boar, technician, year, month, day of the week, interval between collections and age of boar were examined. Boar repeatabilities were 0.21 for volume, 0.32 for concentration, 0.28 for percentage live sperm, 0.21 for motility score and 0.30 for potential doses. Breed of boar effects were significant for all semen measures. Potential doses were highest for Yorkshire (14.7), followed by Landrace (13.7), Duroc (12.9), Hampshire (12.5) and Lacombe (7.7). Differences between technicians were significant for all measures except potential doses. Technicians who collected greater semen volume obtained ejaculates with lower sperm concentration, which resulted in no real difference between technicians for potential doses. Similarly, day of collection was significant for all measures except potential doses. Volume of semen collected was lowest on Saturdays, but Saturday collections had the highest sperm concentration, percentage live sperm and motility scores. Seasonal effects were significant on all traits. Semen volume was lowest in April and increased steadily to peak in November whereafter volume declined. The seasonal pattern for concentration was less definite. Percentage live sperm and motility were highest in January and declined steadily to a low point in August. Potential doses were highest from November to January (13.2–14.2) and lowest from April to June (10.7–10.9). Year effects were also significant and potential doses increased over time. As interval between collections increased, there was as significant increase in semen volume, concentration and potential doses, but interval had little effect on percentage live sperm and motility. Age of boar effects were significant for all traits. Maximum volume, concentration and potential doses were from 24- to 29-mo old boars and lowest volume, concentration and potential doses were from young boars of less than 9 mo. However, percentage live sperm and motility were highest for young boars and declined with increasing age. Key words: Boar, semen, repeatability, breed, age, collection interval