Amino Acid Case Study - (Growth In Pigs)Abstract Folic Acid Supplementation Can Improve the Reproductive Performance of Sows. Lee I. Chiba, John T. Eason, and Robert A. Dawkins Background Information and Objective In recent years, many producers are weaning pigs earlier and following intensive production schedules in an effort to increase reproductive efficiency. These management practices can place high biological demands on today's sows. Obviously, a proper nutrition of the sow becomes an integral part of the management system in maximizing reproductive efficiency and profitability of swine enterprises. Folic acid is a water-soluble vitamin, and it can be produced by bacteria in the intestine. Until recently, the folic acid content of practical diets and bacterial synthesis were believed to be adequate to meet the pig's requirement. Since the early 1980s, however, there have been several reports indicating that folic acid supplementation can have beneficial effects on the reproductive efficiency of swine. As a part of the Southern Regional sow project, an experiment was conducted to evaluate the effect of folic acid supplementation on the reproductive performance of sows. Experimental Procedures, Results & Summary Corn-soybean meal basal diet was calculated to contain .34 parts per million (ppm) folic acid, and met or exceeded other nutrient requirements for breeding swine. The basal diet was supplemented with 0, 1, 2 or 4 ppm folic acid. Sixty-six crossbred gilts and multiparous sows were assigned to dietary treatments based on breeding weight, parity and ancestry at least 21 days before breeding, and remained on their respective treatments continuously throughout gestation and lactation for three reproductive cycles. Each female was offered 1.81 kg of diet/day during the breeding and gestation periods, but the allowance was increased to 2.27 kg/d during the winter months (December, January and February). Females were allowed ad libitum access to feed during lactation. Sows were culled when they failed to conceive after three breedings or developed other problems. The total number of pigs born increased from 9.5 to 10.6 pigs/sow as supplemental dietary folic acid increased from 0 to 4 ppm. The baby pig survival rate was not influenced by the dietary treatment, consequently the advantage in litter size obtained at birth was maintained throughout the 21-day lactation phase (8.6 to 9.6 pigs/sow). Similarly, although there was no difference at birth, total litter weight at day 21 of lactation increased from 98 to 110 lb. as the folic acid content of diets increased. The weight loss of sows during lactation increased as dietary folic acid increased, possibly a reflection of larger litter sizes being nursed by sows treated with folic acid. However, days required to return to estrus after weaning were not affected by the addition of folic acid, and there was no diets by study parity interaction on the litter size, indicating that the increase in weight loss during lactation had no immediate or even long term adverse effects on the reproductive performance of sows. There was no effect of folic acid on litter size when data from all five experiment stations were combined, which was unexpected. However, considering the preponderance of data supporting the beneficial effect of folic acid, the litter size is likely to be improved by supplemental folic acid. In a comprehensive review of published reports on folic acid, a collaborator of this regional project reported that all studies showed a positive response to folic acid in the reproductive efficiency. It has been suggested that folic acid should be included routinely in the breeding herd vitamin premix, even though the need for supplementation during lactation has not been demonstrated and the sow's body can store only a limited amount of this vitamin. In addition, folic acid supplementation might be more beneficial in some instances where the ovulation rate in the female is greater such as breeds that ovulate more, sow herds in advanced parities and flushed gilts or sows. In those situations, folic acid supplementation is likely to improve the litter size by reducing embryonic mortality rates. [For a summary of the data from all five experiment stations (Alabama, Florida, Louisiana, South Carolina and Virginia), please see "Harper, A. F., M. D. Lindemann, L. I. Chiba, G. E. Combs, D. L. Handlin, E. T. Kornegay, and L. L. Southern. S-145 Committee on Nutritional Systems for Swine to Increase Reproductive Efficiency. 1994. An assessment of dietary folic acid levels during gestation and lactation on reproductive and lactational performance of sows: A cooperative study. Journal of Animal Science 72:2338-2344."] |
