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This study aimed to determine semen quality and seminal biochemicals at 1 ejaculate, puberty, and maturity of Holstein bulls administrated with GnRH, hCG and testosterone. Holstein male calves (n=16, 8 mo old) were divided into four groups, 4 in each. During 10-weeks interval, each animal was bi-weekly i.m injected with saline (2 ml), 2 ml GnRH, 1500 IU hCG, and 2 ml testosterone. Results indicated the earliest ages to 1 ejaculation, puberty, and maturity by hCG. Ejaculate volume was higher (P<0.05) by GnRH. Sperm motility and livability increased (P<0.05) by GnRH. Seminal total proteins (TP) and albumin (AL) decreased (P<0.05) by GnRH and hCG. Globulin (GL) and fructose decreased (P<0.05) by treatments in the 1 ejaculate. At puberty and maturity, TP, AL, and fructose increased (P<0.05) by treatments. GL increased (P<0.05) by GnRH and hCG. AL:GL increased by GnRH and testosterone at puberty, and by testosterone at maturity. Triglycerides in 1 ejaculation increased (P<0.05) by GnRH. At puberty, HDL, LDL, cholesterol, and triglycerides in GnRH; LDL, cholesterol, and triglycerides in hCG; and triglycerides in testosterone increased (P<0.05). while HDL in hCG and testosterone decreased (P<0.05). At maturity, LDL and cholesterol in hCG, and triglycerides in GnRH and hCG increased (P<0.05), while HDL decreased (P<0.05) by treatments.This study concluded that the treatment of Holstein male calves with GnRH or hCG (once/two weeks) for 10 weeks prior to puberty (8 months of age) leads to early sexual puberty-maturity ages and semen with good quality and chemical composition.

journal of animal and poultry production

Effect of Hormonal Administration on Reproductive Development of Holstein Bull Calves and Concomitant Changes in Semen Characteristics and Seminal Plasma