Presented at the Neonatal Society 2001 Autumn Meeting.

Antipatis C¹, Finch AM¹, Ashworth CJ²

¹ Development, Growth and Function Division, Rowett Research Institute, Bucksburn, Aberdeen
² Applied Physiology Department, SAC, Bucksburn, Aberdeen

Introduction: Many litters contain at least one piglet that is significantly smaller than its littermates. Low birthweight piglets are more likely to die during neonatal life, while those that do survive grow more slowly and have compromised physiology throughout life (1) than their heavier siblings. As there are few opportunities to remedy the detrimental consequences of low birthweight post-natally, it is important to devise ways of alleviating low birthweight and increasing uniformity in piglet birthweight prior to birth. We have previously shown that moderate reductions in vitamin A on day 30 of pregnancy increase uterine retinol binding protein levels (2), which are known to be important for fetal development. This study therefore examined the effects of moderate maternal vitamin A deficiency in early or late pregnancy on porcine fetal growth.

Methods: Three groups of 4-5 Large White x Landrace gilts were fed either a control (Con) diet or a vitamin A deficient diet either for one oestrous cycle before mating and throughout pregnancy (Con-VAD) or for 100 days prior to mating and for the first 30 days of pregnancy, followed by the control diet for the remainder of pregnancy (VAD-Con). Piglets were weighed as soon as possible after birth. The within litter distribution in piglet weight was assessed visually using cumulative probability plots (3). The effect of treatment on the within litter variance in fetal and piglet weight was analysed by comparing the pooled variance (Sp2) between treatment groups.

Results: Moderate reduction in maternal vitamin A levels during early, but not late, pregnancy reduced the incidence of low (< 0.8g) birthweight piglets and promoted uniformity in weight within litters. However maternal vitamin A deficiency did not improve the number of piglets born alive.

* P<0.05

Conclusions: Appropriately timed alterations in maternal retinol status may provide opportunities to reduce both the number of low birthweight piglets and the within litter variability. This work suggests that further research is needed to elucidate the role of vitamin A metabolism in potentially reducing welfare and practical disadvantages associated with variable birthweight.

Acknowledgement: This work was funded by SEERAD.

References
1. Ashworth, C.J., Finch, A.M., Page, K.R., Nwagwu, M.O., McArdle, H.J. (2001) Reproduction, Supplement 58.
2. Ashworth, C.J., Antipatis C. (1999) Reproduction in Domestic Animals 34, 103-108.
3. Finch, A., Zuur, G, Ashworth, C.J. (1999) Early Human Development. 55, 185-186.