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Failure of vitamin A to alter litter size in swine when injected at breeding and various stages of gestation.

A.E. Pusateri*, M.A. Diekman, and W.L. Singleton

Purdue University, West Lafayette, IN.

To determine the effectiveness of vitamin A injections during breeding and various stages of gestation on subsequent litter size, 1375 sows were assigned randomly (125 sows per treatment) to 11 treatment groups. Vitamin A (1,000,000 IU) was dissolved in corn oil and injected intramuscularly into the neck of sows on one of the following days: weaning, day 0, 2, 6, 10, 13, 19, 30, 70 or 110 post-breeding. Sows in the control group were injected with corn oil on corresponding days. The study was conducted in a fully enclosed commercial farrowing operation located in central Indiana. Sows which returned to estrus within 10 days of weaning were bred twice daily during estrus to different boars. Sows were housed in gestation crates following breeding. Farrowing was accomplished on an all-in/all-out basis. A total of 398 sows were removed from the study following treatment assignment or treatment. Farrowing rate and live litter size for each treatment group are presented in the table.

Injection of vitamin A did not alter live litter size (p>.05). In addition, vitamin A did not influence (p>.05) live litter weight, number of live runts or gestation length (data not shown). Compared to other parity groups, parity 6 or greater sows had less pigs per litter and lower litter weight (p<.01), but pig weight, number of runts, number of mummies or gestation length were not affected by parity (p>.1). These data indicate that injection of vitamin A at weaning, breeding or various days throughout gestation was not effective in increasing litter size.

Key Words: Sows, Vitamin A, Litter size


Farrowing %

Live litter size

Oil Control


9.7 ± .4

Vit A, Weaning


9.5 ± .3

Vit A, Day 0


10.6 ± .3

Vit A, Day 2


9.5 ± .3

Vit A, Day 6


10.0 ± .4

Vit A, Day 10


10.0 ± .3

Vit A, Day 13


9.6 ± .3

Vit A, Day 19


9.7 ± .4

Vit A, Day 30


9.7 ± .3

Vit A, Day 70


10.2 ± .4

Vit A, Day 110


9.9 ± .3

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