The effects of level of feeding of sows during pregnancy. II. Changes in body weight

1. Twelve groups of 3 litter-sister Large White gilts were given during three successive pregnancies a daily meal allowance of either 6 lb. (Group A) 3 lb. (Group B) or 3 lb. for 76 days followed by 6 lb. until parturition (Group C). During 8-week lactation periods all received the same daily allowance of 4 lb. meal plus 0·8 lb. for each piglet suckled. 2. Net weight gains during the three successive pregnancies respectively were: Group A, 114, 97 and 79 lb.; Group B, 11, 10 and 7 lb.; Group C, 47, 44 and 35 lb. The differences between groups were highly significant (P<0·001) and there was a significant parity interaction (P<0·05) in that Group A sows showed a significant decline in net weight gain from parity to parity whereas those of Groups B and C did not. No relationship was found between net weight gain and litter weight at birth. 3. Weight changes during the three successive lactation periods respectively were: Group A, –37, –41 and –36 lb.; Group B, 2, 14 and 4 lb.; Group C, –10, –14 and –5 lb. The differences between groups were significant to various degrees in different lactations. There was no relationship between weight changes during lactation and total litter weight at 3 weeks of age. 4. Overall weight changes from first service to third weaning were: Group A, 160 lb.; Group B, 72 lb.; Group C, 71 lb. The differences between Group A and Groups B and C were highly significant (P<0·001). 5. The implication of the results as an indication of feed requirements for reproduction is discussed.