Effects of dietary vitamin supplementation and semen collection frequency on reproductive performance and semen quality in boars.

The present study was undertaken to assess the relevance of increasing the daily provision of dietary vitamins on vitamin metabolic status and semen characteristics of boars under controlled and commercial conditions as well as to evaluate the efficiency of this vitamin supplement to allow boars to cope with intensive semen collection frequency. In the first experiment, 39 boars were allocated to 2 dietary treatments, a basal diet (control) and the basal diet supplemented with extra fat- and water-soluble vitamins (Vit). Within each treatment, boars were submitted to 2 regimens of semen collection frequency: 3 times per 2 wk (3/2) and 3 times per week (3/1) over a 12-wk period. Afterwards, all boars were intensively collected (daily) for 2 wk. A resting period of 4 wk followed, and all boars were collected 2 times per week. Thereafter, collection frequencies were reversed, and the same procedure was followed until the end of the intensive collection period. A second experiment was conducted in commercial conditions at a commercial stud, and 252 boars were randomly allocated to the control and Vit dietary treatments. All boars were collected 2 times per week over a 6-mo period. Classical measurements of ejaculate and sperm quality were assessed, and blood samples were collected throughout both experiments to quantify vitamin concentrations. In the first experiment, vitamin concentrations in blood and seminal plasma increased in Vit boars (P < 0.05); however, vitamin concentrations were not affected by collection frequency (P > 0.14). The Vit supplement did not affect sperm production or sperm quality (P > 0.28), although semen volume increased during the 12-wk periods for Vit boars (P < 0.05). The 3/1 boars produced fewer doses per ejaculate than 3/2 boars (P < 0.01); however, the cumulative sperm production for the 12-wk periods increased by 19% in 3/1 boars compared with 3/2 boars. In the second experiment, blood plasma concentrations of vitamin B(9) were greater (P < 0.01) in Vit than control boars. The vitamin supplement did not increase sperm production of boars (P > 0.61). In conclusion, dietary supplements of fat- and water-soluble vitamins increase the amount of vitamins available for the animal, and the collection frequencies had no effect on vitamin status. Moreover, in spite of an effect on the ejaculate volume, the dietary supplement of extra vitamins had no effect on sperm production or quality.