ABSTRACT

Three experiments evaluated the effect of vitamin E supplementation on the growth and reproductive performance of female pigs. In the first experiment, twelve Large White x Landrace hybrid guts were used to determine the effect of different levels (0, 7.5, 1 5 and 30 JU) of vitamin E supplementation on reproductive performance and weaning traits of sows and their offspring. In the second experiment, eight sows were randomly assigned to two groups of four animals each and used to study the ovarian status of supplemented and non- supplemented sows. Measurements taken were ovarian weight, ovarian diameter, number of observable follicles measuring 7mm and above, and the number of the corpus alhican,s from previous ovulation. In the third experiment, sixteen guts were used to study the effect of Vitamin E supplementation on the growth, attainment of puberty (time of first estrus); and the estrous cycle proestrus (early follicular), estrus (late follicular), metestrus (early luteal) and diestrus (late luteal). Hormonal assays were carried out on four sows (two each from the supplemented and from the non-supplemented groups) with blood collected at two hourly intervals (over 8 hours) from indwelling catheter placed on the external jugular vein to determine the effect of vitamin E on the gonadotropins. Results show that the number of offspring and birth weight were influenced by the vitamin E supplementation (P<0.05). At 0, 7.5, 15 and 30 IU of vitamin E supplementation, the average litter size were 8.67, 9.00, 12.67 and 11.00 piglets, respectively. The average piglet weights at birth were highest (P<0.01) in the zero supplemented levels (0.97kg) as against 0.83kg (7.5 IlU) 0.73kg (15 JU) and 0.78kg (30 ITJ). There was no significant difference (p>O.05) in the average litter size at weaning. Body weight before farrowing (BWTBF) was positively correlated with initial body weight (IBWT) at 0 (r = 0.778), 7.5 (r = 0.998), 15 (r =0.655) and 30 IU(r=0.866); (p<O.05). A positive correlation also existed between the numbers of offspring born and the maternal body weight in all the treatment. The gestation length did not vary (P>0.05) among the groups. However, there was a negative correlation between the gestation length and the litter size at birth(r = - 0.115, p>O.05) at 15 Hi and r -0.933 for 30 I U. There were numerically more mature follicles from the left than the right ovary (51.84% vs. 41.16%) even though the results were not significant (p>O.05). In experiment 3, vocalization and restlessness of the sows, swelling and redness of the vulva were significantly different during the varying stages of the estrous cycle (P<0.05). Vulval length and width however were not statistically different (P>0.05). Vocalization was highest around estrus between days 12 and 15, Redness of the vulva ranked highest on day 15 and was least on day 6,The sows were conspicuously restless on days 16 and I 7 while they were not really restless at days 4, 7, and 8 except of course at meal times. The swelling of the vulva was also most pronounced at day 15 and 16 while the swelling as least about day 4. However following supplementation only the swelling was significantly different (P<0.05) among the experimental groups. The values of Leutinizing hormone (LH) in the supplemented group were 5.06ng/ml versus 4.65ng/ml for the non-supplemented animals. The same pattern was also observed for follicle stimulating hormone (FSI-I) (2.94 m.i.u/ ml vs. 2.79 m.i.0 /ml). The highest values of LH are observed during the period of estrus (late follicular phase) while the least values were at the metestrus (early luteal phase).The FSH values were the same at the follicular phase but differed at the early and late luteal phases. There was no variation (P>0.05) on the time of attainment of first estrus in growing animals. The duration of estrus was also not different (P>0.05) in the experimental groups with an average of 21 days in all the groups. It was concluded that supplementation of vitamin E should be carried out in gilts at the level of 15 Hi as this gave the highest number of offspring and promoted performance among the pigs.