Effect of L-tyrosine on puberty age, testosterone level and semen quality of Friesian bulls
Abstract: A Total of 30 Friesian bulls averaging 8.5 ±0.16 month of age and 195 ±15 kg body weight were used in this study. Bulls were divided into three similar groups (10 each), according to their LBW and age. Bulls in the 1st group were received single oral dose from L-tyrosine (50 g/bull) at 8.5 months of age (G1), while those in 2nd group were received two oral doses from L-tyrosine (50 g/bull) at 8.5 and 10.5 months of age (G2). Bulls in the 3rd group were fed a basal diet and considered as a control group (G3).
Results revealed that L-tyrosine treatment significantly increased (P<0.01) on LBW in G3 and G2 compared to G1 at 12 month, first appearance of spermatozoa, puberty, and 24 months of age. Age at first appearance of spermatozoa and puberty age were significantly (P<0.001) earlier by about 1.2 and 1.5 and 0.9 and 1.7 months, respectively, for bulls in G2 and G3 groups than the control. Changes in testosterone concentration during the study period were significantly higher in G3 and G2 than in G1. L-tyrosine significantly (P<0.01) increased percentages of progressive motility and livability of spermatozoa, and sperm cell concentration compared with the control at first appearance of spermatozoa, puberty, and 24 months of age.
In general; semen quality significantly (P<0.01) improved at 24 month of age as compared to puberty. Sperm motility and livability and sperm cell concentration significantly (P<0.01) increased with advancing of age in all groups. Morphology defects of spermatozoa head were significantly lower in G2 and G3 than in the control group at first appearance of spermatozoa, puberty, and at 12 and 24 months of age. In addition to proximal droplets were significantly lower in G2 and G3 than in the control group at puberty, and at 24 months of age. There was a significant increase in the number of normal sperm with advancing of bull age as well as significant decreases in proximal droplets and head defects, but no significant changes in midpiece and tail defects.
Keywords: Friesian bull, L-tyrosine, puberty, testosterone and semen quality.
Publication year 2013
Pages 84-92
Availability location معهد بحوث الانتاج الحيوانى-شارع نادى الصيد- الدقى- الجيزة
Availability number
Organization Name
serial title The 4th Scientific Conference of Animal Production Research Institute (APRI)
Author(s) from ARC
Agris Categories Animal physiology - Reproduction
AGROVOC
TERMS		 Sexual maturity. Testosterone.
Proposed Agrovoc semen quality;L-tyrosine;Friesian bull;
Publication Type Conference/Workshop
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