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Pig keeping in the tropics - part 4

Fertility disorders Poor oestrus show in sows It sometimes happens that sows do not come on heat at the expected time. Gilts should normally come on heat at 6 to 8 months of age, and sows should do so within one or two weeks of weaning their litter. If there seems to be no heat, it may just be that the heat has passed unnoticed. | 5 Fertility disorders 5.1 Poor oestrus show in sows It sometimes happens that sows do not come on heat at the expected time. Gilts should normally come on heat at 6 to 8 months of age and sows should do so within one or two weeks of weaning their litter. If there seems to be no heat it may just be that the heat has passed unnoticed. But it may also be a problem related to the health and condition of the animal or a genetic problem passed down from the parents. Gilts that do not come on heat should be replaced. When selecting females for breeding those that have a long and easily detectable oestrus period should be kept. If a mother sow does not come on heat within 14 days of weaning there are various possible causes The suckling period has been too long - the shorter the period the quicker she will come on heat again. She is in poor condition. She has been receiving low quality or too little feed her ration should be increased not decreased after weaning . Very high local temperatures 35 C . A lack of light in her pen. Oestrus can be brought on by Taking the sow away from the piglets during weaning rather than removing the piglets. Putting the sow in a pen next to the boar after weaning. Bringing her into contact with the boar regularly after weaning. If these measures don t succeed a hormone preparation PG600 is sometimes available that can be tried. This should be done in consultation with the vet or the livestock extension service. It occasionally happens that a sow thought to be pregnant i.e. no heats noticed after mating does not finally deliver. In this case a problem Fertility disorders 53 may have occurred after mating resulting in her infertility or a miscarriage. This sow should be culled. 5.2 Diseases leading to fertility disorders Brucellosis and leptospirosis described below can both result in the sow miscarrying. Miscarriage or abortion is a termination of the pregnancy before its proper term with the foetus and the placenta being rejected. Some sows