Effects of Supplemental Betaine to Semen Extenders on Semen Quality in Boars.

The objective of this study was to determine the effects of supplemental betaine in semen extender on estimates of semen quality. Eight intact male pigs were used in a 4x2 factorial study replicated for 3 weeks. Semen was collected from each animal one time per week, diluted into a commercial semen extender (Enduraguard Plus; MOFA, Verona, WI) containing 0, 0.6, 1.2, or 2.4% betaine, and evaluated following dilution (d 1) and after 4 days of storage at 17°C (d 4). Evaluations included sperm motility and mobility estimations using computer assisted sperm assessment (Ceros II, IMV Technologies) and morphological assessment. Statistical ANOVA was performed using the mixed procedure of SAS (9.4). Main effects for statistical analysis included treatment, week, day of analysis, and all interactions. Extender pH and semen concentration were used as covariates and laboratory and collection technician as random effects, where appropriate. On d 1, motility increased with 1.2% betaine (P = 0.045) and tended to increase with 0.6% (P = 0.074) compared to 0%, whereas 2.4% betaine was lower than 0.6% and 1.2% (P < 0.001 and P = 0.002, respectively). Percent motile sperm LS means for 0%, 0.6%, 1.2%, and 2.4% on d 1 were 69.15, 76.29, 76.97, and 65.58% ± 2.95, respectively. Straight line velocity was increased for 0.6% and 1.2% compared to 0% (P = 0.048 and P = 0.015, respectively). On d 4, motility (P < 0.001), straight line velocity (P < 0.001) and percent normal sperm (P ≤ 0.023) in the 2.4 % betaine samples were reduced compared to all other treatments. There was a treatment by day of storage by week interaction for percent of sperm with tail abnormalities (P = 0.042). In general, the addition of 2.4% betaine caused an increase in tail abnormalities. The treatment effect LS means for tail abnormalities for 0%, 0.6%, 1.2% and 2.4% were 4.24, 5.27, 5.20, and 11.62% ± 1.62, respectively. Regardless of day of evaluation, linearity was decreased in the 2.4% betaine treatment (P < 0.001) and tended to increase in the 0.6% and 1.2% compared to 0% (P = 0.093 and P = 0.070, respectively). The results of the current study indicate that the addition of 0.6 or 1.2% betaine to semen extenders can improve sperm motility and mobility without adverse effects on normal sperm morphology. In addition, supplemental betaine at 2.4% has negative effects on estimates of semen quality.