Dietary alpha-linolenic acid deficiency in the rat. I. Effects on reproduction and postnatal growth

The effects of a dietary alpha-linolenic acid (18 : 3 n-3) deficiency on reproduction and postnatal growth in rats were studied during 3 successive gestations and 4 successive generations. Female rats received respectively a semi-synthetic diet in which the lipids were incorporated either as sunflower oil at 1.5% (deficient diet) or as soya oil at 1.87% (control diet). Both diets supplied the same amount of linoleic acid (18 : 2 n-6) (940 mg/100 g of diet), but the sunflower oil supplied 22 times less alpha-linolenic acid than the soya diet (6 mg vs 130 mg/100 g of diet). The results showed that, in our experimental conditions, the alpha-linolenic acid deficiency had no effect on fecundity (% of pregnant females), fertility (number of pups/litter), pup birth weight, food intake and weight of pregnant or lactating females, or pup growth during suckling. However, this deficiency did cause abnormally high rates of perinatal mortality from birth to postpartum day 3, namely on the average, for successive gestations: 18.5% in deficient pups vs 5.2% in the controls, and for successive generations: 16.6% in deficient pups vs 5.3% in the controls. Rat n-3 PUFA requirement during reproduction has been discussed; it appears to be more than 100 mg/100 g of feed. But this need should also be estimated in relation to n-6 PUFA supply; for female rats during reproduction, the ratio n-6: n-3 should be less than 10.