An update on North American boar stud practices

This survey included 44 boar studs from Canada and the USA with a total of ∼10,000 boars. Studs with 51–500 boars accounted for 84% of respondents. More than 90% of boars were housed in stalls. Evaporative and mechanical cooling systems predominated and boars were typically fed based on body condition. The predominant age of boars was 1–2 years with annual culling rates between 20 and 70%. The primary reasons for culling included genetic improvement, semen quality and feet and leg issues. Collection occurred commonly on Mondays and Thursdays and boars were rested 3–7 days between collections. The average sperm produced per boar per week was 51–150 billions and resulted in 21–40 doses per boar per week. Most studs collected boars using double gloves and disposable cups or liners and used pre-warmed containers. Ejaculate pooling was practiced by >60% of studs. Evaluation of semen for motility was performed with 0–5 min of warming in extender with viewing at 100–400× magnification. Concentration estimation occurred by photometer and CASA for 88% of studs. Ejaculate discard occurred for reasons of poor motility, abnormal sperm and bacteria. Most studs retained extended samples for 3–7 days for quality control. Discard rates were most common between 1 and 10% and were related to individual boar and season. Doses of semen contained 2–4 billion sperms, with final sperm numbers adjusted for fertile sperm and packaged as doses in tubes and bags with 60–100 mL.