tailieunhanh - Pig keeping in the tropics - part 3

Pig breeding Managing the sows Sows that are to be kept for breeding should be selected and separated from the litter at about 3 months of age. They should not be allowed to get too fat because this will create fertility problems. | 4 Pig breeding Managing the sows Sows that are to be kept for breeding should be selected and separated from the litter at about 3 months of age. They should not be allowed to get too fat because this will create fertility problems. They should get a little exercise to remain in good condition. Young sows are mature enough to conceive at about six months of age. They should not be served mated too early however as it is better to wait until they are fully grown. If they are well fed and healthy this will usually be at about eight or nine months. Mating too early will result in small litters problems at birth a loss of condition and poor growth of the sow. Mating can only be successful during the sow s period on heat oestrus . Sexually mature non-pregnant and non-lactating sows come on heat for two or three days about every three weeks. However if the boar is kept separate from the sows and gilts young sows not yet mated as he should be it may sometimes be difficult but nevertheless essential to recognise the heat see below . Selecting sows for breeding When selecting the sows to be kept for breeding the following points should be considered They should have at least 12 normal teats. They should be the biggest and heaviest of the litter. They should have strong legs and walk well. Their parents should be good breeding animals capable of producing good litters at regular intervals. Recognising the heat Twice a day in the morning and in the evening a check should be made of the sow s oestrus condition. This should be done some time after feeding preferably in the morning. Doubtful cases can be looked at again in the afternoon. Differences in breed and climatic variations in the tropics sometimes make it difficult to recognise oestrus. The Pig breeding 33 first sign is a redness and swelling of the vulva which is more obvious in gilts than in sows. Another sign is that other sows in the pen start to mount the sow on heat. The clearest indication is the reaction of