Abstract
It was the aim of the present study to test whey as protective protein for the sperm cell in the long-term boar semen preservation medium TRIXcell. Analyses of sperm cell motility using computer-assisted semen analysis (CASA) indicated that the whey protein Porex has a similar protective effect as bovine serum albumin (BSA) in maintaining viability of stored boar sperm. Boar sperm diluted in TRIXcell+ maintains commercially acceptable motility (>60%) for 10 days, while swine sperm diluted in the semen preservation medium Beltsville Thawing Solution (BTS) maintains commercially acceptable motility (>60%) for 3-5 days for most boars. To test the on-farm fertility performance of TRIXcell+ compared to BTS, inseminations were started on 35 commercial pig production farms in the summer of 2006. During the period of July 2006 until July 2012 for each farm and each calendar year the mean farrowing rate and litter size for semen diluted in TRIXcell+ and stored for 3-5 days was found higher than that of semen stored for 1-2 days in BTS. Based on data gained from a total of 583.749 sows inseminated through the years 2006-2012, the mean farrowing rate for semen diluted in TRIXcell+ and BTS was 90.4 ± 4.0 and 87.9 ± 3.6, respectively, which is not significantly different. Based on the same data, the mean total number of piglets born alive for semen diluted in TRIXcell+ and BTS was 14.2 ± 0.7 and 13.6 ± 0.6, respectively, which is significantly different. We conclude that whey protein can effectively be used in the long-term preservation medium TRIXcell resulting in a higher litter size.

Key words: Artificial insemination, Boar, Fertility, Semen preservation medium, Whey protein.