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.