REPRODUCTIVE PERFORMANCE OF HEAT-STRESSED NEW ZEALAND WHITE RABBIT BUCKS IN RESPONSE TO DIFFERENT ZINC SOURCES

Abstract

This study aimed to evaluate the effect of zinc supplementation from different sources to heat-stressed New Zealand White rabbit buck diets on some reproductive traits including semen quality, conception rate and litter size. Twenty four mature bucks were randomly assigned into four groups, with six males each. The first group reared under mild condition and received the basal diet with no supplementation. The other three groups were raised under heat stress condition and received the basal diet only or the basal diet supplied with 75 mg zinc either as zinc sulphate (inorganic zinc) or as zinc picolinate (organic zinc), for the second, third and fourth groups, respectively. It was found that dietary zinc supplementation reduced the heat stress-related increases in reaction time, and seminal plasma levels of alanine transaminase (ALT) and malondialdehyde (MDA). Decreased values of serum and seminal plasma testosterone, sperm count, sperm motility and conception rate induced by heat stress conditions were restored by zinc supplementation. Seminal plasma zinc and total antioxidant capacity (TAC) were significantly increased in zinc-treated groups when compared to both control groups in different conditions. Organic source of zinc was more potent than inorganic one in restoring levels of serum testosterone, seminal plasma MDA and testosterone, and sperm motility. From these results, it could be concluded that dietary zinc addition from different sources, especially zinc picolinate (organic form), is helpful in alleviating the negative effect of heat stress on reproductive traits of New Zealand White rabbit bucks.