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Vitamin levels and sow performance

Researchers continue to refine their understanding of the vitamin needs of sows for optimum reproductive performance. Most studies to date have focused on dietary supplemental levels of individual vitamins. For example, Lindemann (1993) summarized 11 university studies in which sows receiving supplemental folic acid showed consistently greater litter size than unsupplemented controls. Similarly, studies have found performance benefits with increased supplemental levels of vitamin A and riboflavin, as measured by pigs per litter, pigs born alive and weaning weight.

Recently, Flowers and Spears (1996) conducted two on-farm experiments in which 13 vitamins were provided at increased levels from 5 days before breeding to 21 days after breeding. Both of the farms in the study were total-confinement farrow-to-finish operations with 1,200 sows each. Control sows received each farm's standard gestation rations, which varied from Farm A to Farm B but exceeded National Research Council (NRC) minimum requirements in estimated vitamin content. For the test treatments, diets were further supplemented to provide the increased levels, and these sows had identical estimated vitamin intake on both farms (Table 1).
Table 1

Like vitamin content in the basic gestation ration, other management practices differed by farm. For example, breeding on Farm A consisted of natural service followed by two artificial matings, whereas breeding on Farm B consisted of natural service mating each day of estrus. However, both farms were well-run operations with excellent production records. Farm A averaged 9.5 pigs born alive per litter the year before the study began, while Farm B averaged 9.8 during the same period.

On each farm, sows receiving the additional vitamin supplementation had significantly better performance than the controls. For example, the farrowing rate on Farm B was significantly higher (P < 0.05) for sows in the increased fortification group--87.4 versus 77.9 percent for the controls. On Farm A, the farrowing rate was numerically greater in sows receiving increased fortification--88.2 versus 84.1 percent (Table 2).
Table 2

The number of pigs born alive was significantly influenced by treatment and parity on Farm A. First and second parity sows receiving increased fortification averaged 10.8 pigs born alive, compared to 10.4 for similar parity control sows (Table 3). There were also significantly more pigs born alive to sows fed increased fortification beyond the fifth parity--11.3, compared to 10.9 from control sows. No effect was observed for sows between parities three and five.
Table 3

On Farm B, the number of pigs born alive was similar for sows receiving increased fortification (9.8) and controls (9.9) regardless of parity. The researchers point out, however, that 90 percent of the sows on Farm B were between parities 3 and 5; thus, an inadequate number of sows in parities 1, 2 and 6 may explain the lack of similar results in early and late parities.

The researchers indicated the response variation by parity on Farm A is particularly interesting. Typically, the productive curve of a sow when measured by pigs born alive is somewhat bell-shaped. Numbers increase in parities one and two, plateau between parities three and five, and begin to decrease with parity six. It has been widely suggested that reproductive efficiency is less than optimal during early parities because the reproductive axis is still developing, and also during later parities because the aging process reduces reproductive performance.

The mechanisms responsible for this pattern are not fully known, but Flowers and Spears note that changes in ovulation rate and embryonic survival are often suggested as the reasons. Possibly the increased supplementation of vitamins during these early and late parities resulted in more liveborn pigs by enhancing the development of the reproductive axis in young, growing gilts and sows, and by delaying age-related changes in the reproductive system of older sows.

On Farm B, the 9.8 percent increase in farrowing rate was a consistent observation in each of the four replicates. The researchers note that the reason for this increase is not readily apparent, but they point out that the sows receiving increased supplementation had a higher percentage of litters with four pigs or less than controls. (There was also a higher percentage with more than 15 pigs per litter.) Because it normally takes four or five pigs to maintain pregnancy, the researchers point out that such small litters should not have occurred.

However, they hypothesize that the increased vitamin supplementation altered the physiological processes involved in maternal recognition and implantation in the pig to sustain pregnancies with such small numbers. The fact that no litter of less than four total pigs born was observed in the control sows provides support for this speculation, but the researchers note that more research is required.

Whatever the mechanism, the North Carolina researchers note these results demonstrate that increased vitamin supplementation during post-weaning and early gestation improved farrowing rate and number of pigs born alive in commercial swine operations tested.

References:

  • Flowers, W.L., and J.W. Spears. 1996. Effect of vitamin supplementation during breeding on sow reproductive performance. North Carolina State University (report).
  • Lindemann, M.D. 1993. Supplemental folic acid: a requirement for optimizing swine reproduction. J. Anim. Sci. 71:239.

 
Pork Quality Assurance

Because food safety is an issue of increasing public awareness, the National Pork Producers Council (NPPC) introduced the Pork Quality Assurance (PQA) program in 1989 to help producers meet consumer expectations for safe, wholesome pork products.

The PQA program emphasizes good management practices in the handling and use of animal health products. It encourages producers to evaluate their herd health programs with a verifier every year and then to recertify every two years. The NPPC has designated veterinarians, Extension personnel and agricultural education instructors to serve as verifiers.

There are now almost 25,000 producers, collectively marketing over 50 percent of the hogs in the U.S., enrolled in the PQA program's three levels. DSM Nutritional Products' Animal Nutrition and Health is a PQA Partner company and supports producer involvement in the PQA effort.

Nutrafacts readers who are interested in learning more about the PQA program, including how to become a verifier, should call the NPPC's PQA department at 800-456-7675.

 
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