Effects of dietary nitrogen level on semen characteristics of sheep

Abstract

The research looked upon the influence of dietary nitrogen level or equivalent ruminal degradable protein (RDP) on semen biochemistry characteristics and freezability of sheep spermatozoa. Eighteen young rams, were allocated in tree blocs of six animals each, according to scrotal circumference. The rams were randomly distributed to three treatments: A (control) a maintenance diet, B and C, maintenance diet added 20 g and 40 g of urea (75% and 150% of RDP), respectively. Three weeks after dietary adaptation, blood and semen samples were collected every week for nine weeks, to analyze blood plasma and semen levels of urea, transaminases (AST and ALT), acid phosphatases, frutose and citric acid. Once a week for six weeks the motility percent, motility rates, abnormal acrosome percent and abnormal total percent between pre-freezing and post-thaw of cryoprotected semen samples were freezing, evaluated and calculated to mathematical difference. There was a linear regression (p < 0.01) between levels of UP 18.26 mg%, 34.42 mg% and 49.77 mg%, and levels of semen urea 32.47 mg%, 51.44 mg% e 60.46 mg%, for treatments A, B and C respectively. There was no effect of treatments on fructose, citric acid or enzymes acid phosphatase and transaminases levels, and of motility percent, motility rating, abnormal acrosome percent and abnormal total percent differences. The excess of nitrogen or RDP dietary levels elevates urea in blood plasma and semen, but did not affect biochemistry characteristics and freezability of rams spermatozoa.