Breeding soundness evaluation of extensively managed bulls in Costa Rica.
This paper describes the results of single breeding soundness evaluations (BSE) in 898 Bos indicus, Bos taurus and B. indicus x B. taurus bulls, 1 to 12 yr old, extensively reared in different climatic regions of Costa Rica and representing approximately 2% of the total breeding bull population. Thirty-three percent (n = 296) of the bulls were classified as unsound for breeding owing to clinical problems (9.1%, n = 82), low scrotal circumference (SC) being the most common finding, followed by unsatisfactory sperm morphology (23.9%, n = 214). The prevalence of bulls unsound for breeding was lowest in Bos indicus (29%, P < 0.01), intermediate in B. taurus (41%), and highest in B. indicus x B. taurus (48%). The percentages of abnormal sperm heads, acrosomes and midpieces tended to be higher in the ejaculates of bulls with softer testicular consistency (P < 0.001), a long scrotum (P < 0.01) or a low SC (P < 0.05), and such bulls were more often classified as being unsound for breeding (P < 0.05). Frequencies of sperm abnormalities were higher in bulls < 2 yr of age than in older males (P < 0.01) and were highest in B. indicus x B. taurus bulls (P < 0.001). The results confirm differences between species in their adaptability to a tropical environment and support earlier evidence of an association between SC, testicular consistency and scrotal length clinical parameters, and testicular function in bulls.
Chacón
J
J
Department of Animal Reproduction, School of Veterinary Medicine, Universidad Nacional (UNA), Heredia, Costa Rica.
Pérez
E
E
Müller
E
E
Söderquist
L
L
Rodríguez-Martínez
H
H
D000818:Animals; D001947:Breeding / Q000379:methods* / Q000592:standards; D002417:Cattle / Q000033:anatomy & histology / Q000502:physiology; D002980:Climate; D003364:Costa Rica; D003433:Crosses, Genetic; D008297:Male; D012611:Scrotum / Q000033:anatomy & histology; D012661:Semen / Q000166:cytology; D013094:Spermatozoa / Q000002:abnormalities / Q000166:cytology; D013737:Testis / Q000002:abnormalities / Q000033:anatomy & histology