Fertility and Application of GnRH in Repeat Breeder Cows

In this investigation, thirty Repeat Breeder cows which were in good condition and well managed were used as material. These animals were divided into three groups. Ten cows in group 1, were given intra -venous GnRH (0.02 mg). Ten cows in group 2, were injected intra venous GnRH (0.01 mg). Ten cows in group 3 were served as control. Cows which had been registered as free from genital tract infection and from various kind of uterine pathology were included in experimental groups. The rectal palpation was performed before artificial insemination and GnRH administration. In addition for determining the progesteron levels, blood serum samples were withdrawn before artificial insemination (day 0) and twenty first day of oestrus cycle. Artificial insemination was performed according to external sings of oestrus behaviour. Pregnan cy rates of 1, 2, and 3. groups were 60 %, 30 %, and 40 % respectively. However levels of progesteron in all groups were determined as same with clinical sign of oestrus and pregnancy periods. Percentage of pregnancy in all groups were tested with chi-square test and result were found statistically insignificant (P<0.05) however considered to be useful that GnRH (0.02 mg/cow) is given to Repeat Breeder cows in the insemination time. Keywords : Repeat Breeder, Cows, Gonadotropin Releasing Hormone (GnRH)