The aim of the work was to determine whether multiple small doses of GnRH induce an increase in testicular blood flow and scrotal temperature in rams. The experiment was performed during the late breeding season (May-June) with 14 one-year-old rams. Seven rams received hourly doses of 7 ng of a GnRH analogue (busereline acetate) iv starting at 8:00 on the morning, and the other seven rams remained as controls. One week later, treatments were overcrossed. One hour before the first GnRH dose (7:00), and 0, 1, 2, 4, 7 and 10 h later, ultrasonographic examinations of the testes were performed with a B-mode ultrasound scanner with a 7.5 MHz linear array transducer. Each testicle was examined separately by placing the transducer vertically. Images were analysed with specific software using the spot metering technique in four spots with a diameter of 1 cm on the same place of the image. At the same times, rectal, anal and scrotal surface temperatures were measured with a laser thermometer. Pixel intensity was lower with time (blacker, p < 0.0001), as a consequence of GnRH treatment (p < 0.0001). Differences between pixel intensities were significant starting 1 h after the first GnRH dose (p < 0.0001). Perineal temperature (33.9 ± 0.2°C) was not affected by treatment or time (p > 0.1). Rectal temperature was similar in both groups (p < 0.05) until 4 h after the beginning of the treatment (13:00 h). The differences between treatments increased since 4 h after the first dose of GnRH. Scrotal surface temperatures were not affected by treatment (p > 0.1). We concluded that multiple small GnRH doses trigger a rapid increase in testicular fluid content not accompanied by changes on scrotal surface temperature.

No abstract

Contact with oestrual ewes induces an increase in LH and testosterone concentrations in rams. LH provokes an increase in testicular capillary permeability in rodents and an increase in testicular fluid in rams. Therefore, the objectives of the present experiment were to determine whether contact with oestrual ewes, including courtship and mating, induces an increase in testicular fluid content and scrotal temperature in rams. During the breeding season, after 2 weeks isolated from females, a total of 18 tests were performed using one ram with one ewe. The rams were allowed to court and mate the ewes during 20 min. Testosterone blood concentrations were measured by RIA from blood samples taken before and immediately after each test. Rectal, scrotal surface and anal skin temperatures were measured before the test, at the end, and 30 min later. At the same moments, ultrasonographic examinations of the testes were performed. Testosterone concentrations increased after the tests (p = 0.016), and ultrasound images were darker at the end of the tests and 30 min later (p < 0.0001). Rectal, anal skin and scrotal temperatures increased at the end of the test, but decreased 30 min later to initials values. The stimulus of oestrual ewes determined an increase in testosterone secretion, which was associated with an increase in testicular fluid content. Fluid content remained increased at least for 30 min after the end of the ram-ewe contact. Contact with oestrual ewes triggered an increase in testicular fluid that remained higher after the end of the test.

No abstract

Primiparous ewes and multiparous ewes show physiological differences during pregnancy, which can have an impact on the development of their offspring. The objective of this study was to compare the changes in the metabolic profile and in the size of some foetal bones throughout gestation between primiparous and multiparous ewes. Twelve primiparous (PM) ewes and 14 multiparous (MT) ewes were used. According to the dates of lambing, two groups of ewes were formed: Group 1 (G1, n = 6 PM and n = 7 MT) and Group 2 (G2, n = 6 PM and n = 7 MT). The body weight, body condition score, metabolic and foetal morphometric parameters were determined from before conception until the end of gestation. After lambing, the body weight and survival rate during the first 72 hr of life of lambs, as well as the maternal behaviour score were recorded. The PM ewes were lighter (p < .01) and had a greater mobilization of body reserves during gestation, mainly evidenced by a greater serum concentration of NEFAs and lower serum concentration of total proteins (p < .05) compared with the MT ewes. The parity did not affect the foetal morphometric variables. The lambs of MT ewes were heavier at parturition (p = .002) and tended to have a greater survival rate than those lambs of PM ewes (p = .09). In conclusion, PM ewes and MT ewes differ in their metabolic profile throughout the gestation. However, in the present study, we did not find parity differences in the dimensions of foetal bones during growth in gestation.