EFFECT OF DIETARY SUPPLEMENTATION WITH VITAMINS E AND C ON THE PRODUCTIVE PERFORMANCE OF PIGS
Two experiments were conducted at the piggery unit of the Department of Animal Science Farm, University of Nigeria, Nsukka from June 2010 – September 2011, to determine the effect of dietary supplementation with vitamins E and C on the productive performance of pigs. The first experiment assessed the effect of dietary combinations of different levels of vitamins E and C on the growth performance of weaner pigs. Thirty six, Eight weeks old weaner gilts were used for this trial. They were randomly assigned to nine experimental treatment diets having different combinations of vitamins E and C (0 mg vitamin C/0 iu vitamin E (T1), 250 mg vitamin C/0 iu vitamin E (T2), 500 mg vitamin C/ 0 iu vitamin E (T3), 60 iu vitamin E/0 mg vitamin C (T4), 60 iu vitamin E/250 mg vitamin C (T5), 60 iu vitamin E/500 mg vitamin C (T6), 120 iu vitamin E/0 mg vitamin C (T7), 120 iu vitamin E/250 mg vitamin C (T8), 120 iu vitamin E/500 mg vitamin C (T9) with four gilts per treatment. The gilts were housed in pairs making up two replicates per treatment. The initial body weights and linear body measurements of the gilts were recorded before the start of the experiment. Thereafter, weekly body weights and linear body measurements were taken and continued till the gilts attained puberty at the age of 5 months. One experimental diet with 18% crude protein (CP) and 2800 kcal/kgME was formulated for the gilts in the nine treatments but had different levels of vitamins E and C assigned to each treatment. The vitamins were administered through the feed at the time of feeding. In experiment 2, sixteen gilts were selected out of 36 gilts from experiment 1 and randomly assigned to four dietary treatments to evaluate the effects of the combinations of vitamins E and C on the reproductive performance of gilts. Each treatment was replicated twice with two gilts per replicate making up four gilts per treatment. One experimental ration containing 15% CP and 2500kcal/kgME was used but different levels of vitamins E and C for each treatment were added to the feed at the time of feeding. The gilts were placed on the gestation/lactation diet immediately after selection and were allowed to attain their second estrus before mating took place. The body weight of the gilts were recorded before mating following the manifestation of second estrus and date of mating recorded. Gilts were fed 2.0kg of 15% CP diet each day when pregnancy was confirmed. Weekly body weights of the gilts were subsequently taken throughout the gestation period. At farrowing, their ration was increased to 2.6kg per pig per day until piglets were weaned at the age of 8 weeks. The birth weights of the piglets were recorded within 24 hours of parturition, and subsequently piglet weekly body weights were recorded until weaning. Similarly, the body weights of the lactating sows were taken weekly to monitor their body weight changes during lactation. All the data in both experiments one and two were processed and analyzed in accordance with 3 x 3 and 2 x 2 factorial arrangement, respectively in a completely randomized design (CRD). Results of experiment one showed a significant (P<0.05) interaction of vitamins E and C on the body weight of gilts. Weaner pigs on T5 diet containing 60iu and 250mg of vitamins E and C, performed significantly better (P<0.05) in terms of average final body weight (66.13 ± 2.49kg) and growth rate (633.50 ± 30.34g/day) than those in other treatments. However, feed intake and feed conversion ratio were comparable (P>0.05) among the nine treatments. There were significant differences (P<0.05) in flank-to-flank lengths among the gilts in the treatments, with T1 and T2 having the highest values of 67.13 ± 1.82cm and 67.25 ± 1.23cm, respectively. Gilts on T5 had the highest (P<0.05) heart girth values of 83.68 ± 1.22cm, while gilts on T8 and T9 had comparable but lower heart girth of 65.08 ±1.42cm and 65.00 ± 1.06cm, respectively. Significant interaction (P<0.05) effects of vitamins E and C were observed in body weight, weight gain, flank-to-flank and heart girth measurements of gilts at puberty. In the reproductive phase, average litter size values of 7.00 ± 0.58, 8.00 ± 0.41, 8.00 ± 0.00 and 7.00 ± 1.00 for T1, T2, T3 and T4, respectively and the corresponding birth weight mean values of 0.97 ± 0.08kg, 1.05 ± 0.11kg, 1.19 ± 0.00kg and 1.24 ± 0.03kg were not significantly different (P>0.05) among the treatments. Significantly lower (P<0.05) pre-weaning body weight gain (g/day/piglet) was observed for piglets on T1 with mean value of 126.25 ± 5.62 compared to piglets on T2, T3 and T4 with respective values of 150.77 ± 5.00, 150.51 ± 1.59 and 164.12 ± 7.23. A range of 22.07 ± 3.45% to 25.10 ± 0.10% pre-weaning mortality was observed across treatments. Piglets on T1 had the least weaning weight of 7.25 ± 0.28kg which digffered significantly (P <0.05) from piglets on T2, T3 and T4 with weaning weights of 8.42 ± 0.24kg, 8.62 ± 0.08kg and 8.71 ± 0.60kg, respectively. The highest (P <0.05) gestation weight gain of 50.20 ± 0.20kg was recorded for gilts on T3 while the least (P <0.05) gestation weight gain of 44.33 ± 4.48kg was observed in gilts on T1. This study finally suggested that a combination of 60 iu vitamin E/250 mg vitamin C, and supplementation of 120 iu vitamin E alone are more suitable for the improvement of growth performance of pigs managed intensively, while dietary vitamins E and C supplementation at 0 iu vitamin E/250 mg vitamin C, 120 iu vitamin E/0 mg vitamin C and 120 iu vitamin E/250 mg vitamin C combinations during gestation of gilts and their lactation will effectively enhance litter size and lactation performance.