Effect of melengestrol acetate (MGA) treatment or temporary kid removal on reproductive efficiency in meat goats

The effect of vitamin E treatment during preovulatory period on reproductive performance of goats following estrous synchronization using intravaginal sponges

The objectives of this study were to investigate whether the use of intravaginal sponge for estrous synchronization of goats causes oxidative stress, and to examine the effect of administering vitamin E during preovulatory period on reproductive performance of estrous synchronized goats. Estrus was synchronized in 36 non-lactating adult does using intravaginal sponges containing 30 mg of fluorogestane acetate (FGA) for 14 days. All females received 500 IU of eCG at the sponge withdrawal. The goats were allocated at random to two groups balanced for breed, age and body weight. Treatment group (n=18) received 200mg of vitamin E i.m. at the time of sponge removal and again at the time of second artificial insemination. The other 18 goats (control) were administered 1 ml of physiological saline instead of vitamin E on each of these two occasions. All does in estrus was intracervically inseminated at 12 and 24h after the onset of estrus. Blood samples were collected every 72h during the experimental period for evaluation of malondialdehyde (MDA) and vitamin E concentrations. Serum MDA level increased and vitamin E concentration decreased during the period of vaginal sponge application. Following the sponge removal, MDA level declined rapidly to below basal level in the treatment group but remained high in the control group. Conversely, vitamin E concentration increased in the treatment group after the sponge withdrawal and remained at a low level in the control group. No statistically significant differences (P>0.05) were observed between groups in terms of estrous response, conception rate, gestation length or kidding rate. However, the number of multiple births (70.0% versus 50.0%) and prolificacy rate (2.40+/-0.37 versus 1.63+/-0.26 kids per kidding) were significantly higher (P<0.05) for the treatment group than those of the control group. The results indicate that the use of intravaginal sponges for estrous synchronization of goats causes an increase in level of oxidative stress. However, the vitamin E treatment during preovulatory period can prevent the overproduction of reactive oxygen species (ROS), and it may improve the multiple birth rates and the number of kids born in estrous synchronized goats.