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."]
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