Sexual urge, semen quality and seminal oxidative markers of rabbit bucks of different reproductive stages in response to peak of heat stress in Southwest of Nigeria

Rabbits of three reproductive stages were evaluated for their reproductive superiority during peak thermal comfort in Ibadan, southwest Nigeria. Within rabbit population in the study area, bucks were categorized into age groups from the parity records of the farm. Pubertal rabbits (4-5 months old), Mature rabbits (7-9 months old), Adult rabbits (above 1-year-old). Animals were housed individually and allotted randomly into experimental units. This investigation was carried out within February and March when the average daily temperature humidity index (THI) is at the peak. Thirty rabbit bucks per age group, housed individually and randomly allotted to experimental units were used for this study. All bucks were made to serve an artificial vagina, libido was evaluated, and semen collected were assessed for semen characteristics, seminal biochemical and oxidative stress indices weekly from the ninth week. The result obtained revealed that mature bucks had significantly (p<0.05) highest semen volume, mass activity, motility, sperm concentration, total motile and total live spermatozoa among the three age groups. The effect of heat stress was most severe in pubertal bucks as they recorded the least y (p<0.05) semen quality among the three age groups. Seminal lipid peroxidation was significantly (p<0.05) higher in mature and adult bucks compared with pubertal bucks. Seminal total antioxidant capacity was significantly (p<0.05) highest in pubertal bucks but the least value was obtained in mature bucks. It can be concluded that pubertal rabbits possess the best antioxidant stability among the three age group but possessed least semen quality compared with adult and mature buck. Des lapins de trois stages reproducteurs ont ete evalues pour leur superiorite reproductrice pendant le maximum de confort thermique a Ibadan, au sud-ouest du Nigeria. Dans la population de lapins dans la zone d'etude, les mâles ont ete classes en groupes d'âge a partir des registres de parite de la ferme. Lapins pubertes (4-5 mois), lapins matures (7-9 mois), lapins adultes (au-dessus de 1 an). Les animaux ont ete loges individuellement et attribues au hasard dans des unites experimentales. Cette enquete a ete menee en fevrier et mars, lorsque l'indice quotidien moyen d'humidite de la temperature (THI) est au sommet. Trente mâles de lapin par groupe d'âge, loges individuellement et aleatoirement attribues a des unites experimentales ont ete utilises pour cette etude. Tous les mâles ont ete faits pour servir un vagina artificiel, la libido a ete evaluee, et le sperme recueilli ont ete evalues pour des caracteristiques de sperme, des indices biochimiques et oxydants seminaux de stress hebdomadaires de la neuvieme semaine. Le resultat obtenu a revele que les mâles matures avaient significativement (p<0.05) le volume de sperme le plus eleve, l'activite de masse, la motilite, la concentration de sperme, le motile total et le spermatozoa vivant total parmi les trois groupes d'âge. L'effet du stress thermique a ete le plus grave chez les mâles pubertes, car ils ont enregistre la moins de qualite de sperme y (p<0.05) parmi les trois groupes d'âge. La peroxydation seminale de lipide etait sensiblement (p<0.05) plus elevee dans les mâles murs et adultes compares aux mâles pubertals. La capacite antioxydante totale seminale etait significativement (p<0.05) la plus elevee dans les mâles pubertals mais la valeur la moins elevee a ete obtenue dans les mâles murs. On peut conclure que les lapins pubertes possedent la meilleure stabilite antioxydante parmi le groupe d'âge trois mais ont possede la qualite inferieure de sperme comparee a l'argent adulte et mur.