232 OIL SOURCES AND VITAMIN E IN THE DIET ON THE BOAR SEMEN QUALITY PRESERVED AT 5°C

Abstract

Spermatozoa experience physical and chemical stresses during cooling and freezing as a result of ice formation and osmotic changes in the medium. Sperm cryosurvival appears to depend on intrinsic properties of the sperm plasma membrane, such as biochemical composition, thermal behavior, osmotic resistance, and the physical stresses determined by the protocol. The objective of this study was to evaluate the addition of oil sources and dietary supplementation of the vitamin E on boar sperm characteristics cooled at 5°C. Twenty-four mature Dalboard 85 boars, of proven fertility and in routine semen production for artificial insemination, were randomly divided, in factorial arrangement 2 × 3, with 2 oil sources (35 g kg^–1 of soybean or salmon oil were added to the basal diet as a supplement) and 3 levels of antioxidants (150, 300, and 450 vitamin E mg kg^–1). The antioxidant used in this study was vitamin E provided as DL-α-tocopheryl acetate. At the start of the experiment, the age of the boars ranged from 1 to 2 years old. Sperm samples were collected after 0, 1^a, 4^a, 7^a, and 10^a weeks of feeding the experimental diets, and total motility, vigor, hypoosmotic swelling (HOST), sperm morphology, and the fatty acid composition of the sperm were determined. Ejaculates from each of 24 boars were diluted to 3 × 10⁹ sperm to 80 mL in a Beltsville thawing solution diluent and cooled to 5°C in a bottle (3 bottles/boar were cooled). After 24, 48, and 72 h, sperm samples from 1 bottle/boar were analyzed. Treatment differences for sperm parameters were determined using ANOVA. Dietary supplementation with salmon oil reduced (P < 0.05) the proportion of ω6 fatty acid in fresh sperm, specifically of docosapentaenoic acid (22:5ω6), and it increased (P < 0.05) the proportion of docosahexanoic acid (22:6ω3). The motility and HOST of the animals sperm treated with salmon oil at 5°C was superior (P < 0.05) than animals treated with soybean oil, after 24, 48, and 72 h. Feeding salmon oil also increased (P < 0.05) sperm vigor after 24 and 48 h. The motility, vigor, and HOST of sperm at 5°C differed (P < 0.05) over the time they were preserved, with values at 24 h of storage being superior to sperm stored for 48 h and both being superior to sperm stored for 72 h. The percentages of sperm with abnormal morphology increased (P < 0.05) in the semen from animals treated with soybean oil. The percentages of sperm with abnormal morphology were higher (P < 0.05) in the semen at 5°C after 24, 48, and 72 h. Feeding boars salmon oil improved the sperm characteristics of boar semen cooled at 5°C during the 24 and 48 h of preservation time without using a specific diluent designed for this temperature.

Supported by grants from: CNPq, FAPEMIG, Perdigao S/A., MINITUB, and Lagoa da Serra.