Increasing food intake in late gestation improved sow condition throughout lactation but did not affect piglet viability or growth rate

Increasing sow food intake in late gestation prevents loss of sow fatness prior to farrowing. However, this may result in reduced food intake and greater overall fat loss during lactation and has also been associated with increased incidence of agalactia. In this experiment 78 Camborough sows (parities 1 to 3) were given food at one of two levels: either 1·15 × maintenance energy (normal-N sows, 2·3 (s.e. 0·03) kg/day) or 2·00 × maintenance energy (high-H sows, 3·9 (s.e. 0·04) kg/day) from day 100 of gestation until farrowing. Lactation food intake, changes in sow live weight and backfat thickness and piglet growth rates were then measured. Diet digestibility in early lactation was measured using a chromium III oxide marker in the food. There was no change in backfat thickness in late gestation in H sows (0·2 (s.e. 0·25) mm), whereas N sows lost backfat during this period (1·6 (s.e. 0·23) mm, P <; 0·001). There was no difference in lactation food intake between the two groups (6·5 (s.e. 0·13) kg/day) and differences in backfat thickness at parturition were maintained through to weaning. H sows did not show increased incidence of agalactia compared with N sows. There was no difference in diet digestibility between the two treatment groups. Food intake level in late gestation did not affect piglet birth weights, growth rates or mortality. It is concluded that the main benefit of increasing sow food intake in late gestation was to reduce sow backfat loss during the reproductive cycle.

Food-intake level in some Romney Marsh ewes and follicle-group development in their progeny

1. An experiment was carried out in which twelve Romney Marsh ewes were separated into two groups, one kept on a high plane of food intake and one on a low plane during pregnancy and lactation. Skin and wool samples were taken from the progeny at birth and weaning; the ratio Sf/Pf was determined for these ages as well as the proportion of follicles of various kinds and in different phases of activity. The results are compared with those of Ryder from an earlier experiment with Cheviots.2. Differences in food intake of ewes of the order described affected live weight at weaning, but did not significantly affect the differentiation and development of secondary follicles in the foetus nor their number at weaning.3. Lambs in the low-plane group shed secondary fibres at 12 months old much more than those which had been in the high-plane group.4. A partial association of variation in birth Sf/Pf with variation in birth weight was demonstrated, but more than half the variation in this ratio is not accounted for in this way, and the same applies to the variation in birth S/P of the Cheviots in Ryder's earlier experiment. It is suggested that variations in foetal environment and in the early post-natal period affect the rate at which the secondary follicle population in a lamb develops towards its mature genetic maximum.