Plasma urea levels on reproductive parameters of wool-less rams (Ovis aries, LINNAEUS, 1758)

Abstract

The effect of increased plasma urea levels on reproductive parameters of Santa Ines Brazilian breed rams (Ovis aries) was determined during two phases, 60 days in length each. During the first phase, 18 animals divided into three blocks according to scrotal circumference were submitted to the following treatments: diet A1- with nitrogen levels according to ARC (1980); diet B1 - nitrogen levels 133% higher than A1; and diet C1 - nitrogen levels 166% higher than A1. During the second phase, 12 animals divided into two groups received diet A2- with nitrogen levels according to ARC (1980), and diet B2 - nitrogen levels 200% higher than diet A2, respectively. The increase in protein equivalents was obtained by adding 20, 40 and 60 g of feed grade urea to treatments B1, C1 and B2, respectively. Semen was collected daily using an artificial vagina and analyzed twice a week for progressive motility; vigor, whirling, density, pH, concentration, sperm morphology, ejaculated volume and total sperm per ejaculate. Urea concentration was determined weekly in semen and plasma. Urea level increased in plasma and semen (p < 0.0001) during both phases but did not affect the parameters studied.