RESUMO
The present study was conducted on 72 New Zealand white rabbits assigned into two age groups] two and three months]: 36 rabbits for each group of the same age [18 males and 18 females]. For treatment, 24 rabbits [males and females] were given orally a single dose of L-tyrosine, 100 mg/kg body weight; the other 24 rabbits [males and females] were given a daily oral dose of 1 gm L-carnitine/kg. The other 24 rabbits were left as control. All rabbits were kept under complete observation during the experimental period and data obtained were statistically analyzed. There was a steady increase in the body weight with advancement of age; it seemed to be similar for males and females. The treated group revealed a significant higher body weight [P<0.05] when compared to control and treated females, exhibited higher body gain than males. In the treated group, the testicular descent in males and the first onset of male acceptance by females occurred much earlier during the second month of age compared to control. Successful mounting and ejaculation of semen containing spermatozoa for the first time was recorded in the treated bucks at the beginning of the third month of age, much earlier than in control. Testes and ovaries size increased significantly with advancement of age. L-tyrosine and L-carnitine treated groups revealed significant increase in the testicular and ovarian size compared to those in the control group [P<0.01]. It could be concluded that L-tyrosine and L-carnitine, both act as growth promoting factors. They could be used in rabbits for enhancement of puberty in both males and females