The effect of sub-clinical nematode parasitism on reproductive performance in the sow

Abstract

Ten sows were each infected with 300 000 larvae of Oesophagostomum dentatum after weaning their second litter, and subsequent per formance over one parity was compared with that of 10 ‘worm free’ controls. Mean worm burden in the sows when slaughtered immediately after weaning, was 13 480 ±2377. From service to weaning of the litter the mean body weight of worm-free sows increased (+11·3 kg) whereas that of infected sows declined (—13·1 kg) and at slaughter the carcasses of infected sows had lower depths of backfat. Worm-free sows averaged 12·8 pigs born of which 11·3 were born alive, corresponding values for infected sows being 12·4 and 9·5. Worm infection reduced birth weights by 15% but differences were not significant. Litters were equalized at eight pigs shortly after birth, and subsequent weaning weights were 10·5 % lower in those of infected sows despite a 29 % higher consumption of creep feed. Clinical disease was never observed in the infected sows, and no parasitic infection was found in the piglets. It is concluded that sub-clinical infections of O. dentatum in sows may be of economic significance.