Relationship of Dietary Fat Sources with Semen Characteristics, Blood Plasma Metabolites and Scrotal Circumference in Mature Rams

The hypothesis of this experiment was that the various sources of dietary fat with different dietary ratios of polyunsaturated fatty acids (PUFAs) to saturated fatty acids (SFAs) would alter the reproduction parameters of mature rams. Twelve mature rams were randomly allotted to one of four dietary treatments in a com-pletely randomized design. Dietary treatments were: 1) ration with 4% soybean oil (SOY-OIL), 2) ration with 8% full fat soybean (FULL-FAT), 3) ration with 4% calcium salts of soybean oil (Ca-SALT) and 4) ration with 4% tallow (TALL). All diets were kept isoenergetic and isonitrogenous and formulated to be similar in Ca and P contents, while meeting or exceeding the Cornell Net Carbohydrate and Protein System software requirements for the rams used in this study. Diets were supplied to the rams during four months (from August to late December). Semen characteristics, scrotal circumference, and concentrations of cho-lesterol, low-density lipoprotein (LDL), high-density lipoprotein (HDL), triglyceride and testosterone of plasma were measured at the end of the experimental period. Based on the results of this study, diets sup-plemented with Ca-SALT and TALL improved the health of plasma membrane, viability and sperm con-centration (P < 0.05). Rams supplemented with Ca-SALT had also greater volume of semen and total sperm count in ejaculate (P < 0.05) which are two important factors determining the sperm quality. There was no beneficial effect for different treatments based on spermatozoa motility (P > 0.05). Blood concentrations of cholesterol, LDL and HDL of rams supplemented with Ca-SALT were significantly higher than the other treatments. Concentrations of triglyceride, testosterone and scrotal circumference were not affected by the experimental treatments (P > 0.05). As an overall conclusion, the results of this study have indicated the ben-efits for adding Ca-SALT to the diets of adult rams on their reproductive performance.