Validating the assessment of bull sperm morphology by veterinary practitioners.

The objective of this study was to validate the assessment of bull sperm morphology done by veterinary practitioners. Out of 1606 bulls, 1400 (87.2%) and 1344 (83.7%) were designated by practitioners and an experienced andrologist, respectively, as having > 70% morphologically normal sperm. In 92% of the evaluations, there was agreement between the designations chosen.

Associations between sperm abnormalities, breed, age, and scrotal circumference in beef bulls.

The objectives of this study were to determine the associations of breed, age, and scrotal circumference (SC), and their interaction, on the prevalence of sperm abnormalities in beef bulls in Alberta, Canada, and the percentage of satisfactory potential breeders identified during breeding soundness examination solely due to normal sperm morphology. Eosin-nigrosin stained semen smears and evaluation reports of 1642 bull breeding soundness evaluations were procured from 6 veterinary clinics in Alberta. Sperm morphology was determined for at least 100 sperm per bull. The most common defects were detached head [4.86% ± 5.71%; mean ± standard deviation (s)], distal midpiece reflex (6.19% ± 9.13%), and bent tail (1.01% ± 1.54%). Although breed, age, and SC did not significantly affect the prevalence of head or midpiece defects, morphologically normal or abnormal sperm, tail defects were more prevalent in Angus and Hereford bulls compared with other breeds. Overall, solely on the basis of sperm morphology, 1363 (83.0%) bulls were classified as satisfactory potential breeders and the remainder 279 (17.0%) as unsatisfactory (> 30% abnormal sperm, > 20% defective heads, or both). Although not significantly different, the breed with the highest percentage of satisfactory potential breeders was Limousin (90.6%) and the lowest was Hereford (78.8%). That 17% of bulls subjected to breeding soundness evaluation were designated as unsatisfactory solely on the basis of sperm morphology highlights its importance.

Comparative efficacy of bromocriptine, cabergoline and thyroxine in inducing oestrus in bitches.

Forty bitches in anoestrus for more than six months from the last heat, with a serum progesterone level less than 1 ng/ml were subjected to oestrus induction trials using anti-prolactin drugs and levothyroxine, once daily orally for 20 consecutive days. The mean serum progesterone level among them was found to be 0.57 +/- 0.03 ng/ml. Out of 10 animals treated in each group, five (50%) in Group I (bromocriptine @ 50 microg/kg body weight), nine (90%) in Group II (cabergoline @ 5 microg/kg body weight), eight (80%) in Group III (thyroxine @10 microg/kg body weight) and seven (70%) in Group IV (thyroxine @ 5 microg/kg body weight) responded by evincing proestrual bleeding. The mean (+/-SEM) time taken from initiation of treatment to onset of proestrual bleeding in Groups I, II, III and IV was 28 +/- 3.39, 13.44 +/- 3.12 (P < 0.05), 24.50 +/- 3.18 and 33 +/- 2.21 days respectively. The mean (+/-SEM) duration of proestrus and oestrus in the treatment groups was 9.80 +/- 0.86, 10.11 +/- 0.68, 11.25 +/- 0.88 and 10.71 +/- 0.68 days and 7.60 +/- 0.24, 8 +/- 0.29, 8.5 +/- 0.63 and 7.85 +/- 0.46 days respectively. The conception rate in relation to the number of animals responding to oestrus induction in the treatment groups was 80%, 78%, 63% and 57%, respectively. The mean (+/-SEM) gestation length calculated from the last breeding date and litter size in the treatment groups varied from 60.50 +/- 1.55 to 64.00 +/- 0.82 days and 5.14 +/- 0.34 to 6.40 +/- 0.40 respectively.