DEVELOPING THE PIG INDUSTRY.

Taranaki Central Press, Volume IV, Issue 346, 29 January 1937, Page 3

DEVELOPING THE PIG INDUSTRY.

HINTS TO FARMERS ON THE PRODUCTION OF GOOD LITTERS.

Department of Agriculture Notes by

M. J. Scott,

8.A., B.Sc.

[This js the second of a serijs pf articles written by the Advisory Officer to the Department of Agriculture on various phases pf the pig industry in New Zealand. They will appear at regular intervals }n thtebe columns.] Utter Production. When a sow produces a good litter, the owner, unless he is an expert and knows exactly why the litter is so excellent, usually gets as much kick out of the event as if he had collected on the last sweepstake. He takes a reasonable pride in the event, and tells his friends, but perhaps he also wonders just how it happened to be so good. Even the experts are * erhaps a little surprised sometimes ■ the excellence pt their results because they can recollect 'numerous incidents that were likely to do harm to the sow, while she was in pig. Although on the whole the exercise of care at the right time and the intelligent use of the best information is likely to give good results, still, there is no royal road to success in producing good litters. If there were these .would be a commonplace, but instead of that, poOr litters with their resultant loss and disappointment make pigs' unprofitable still on marry farms.

Good Litters. A good litter should weigh between 300 and 4001 b at eight weeks old. the greater the number of piglets the better. Thus 10 piglets of 301 b each is a. better litter than six piglets of 501 b each. A spring balance is a valuable adjunct in assessing litter value. The production of good litters begins with the shedding of the eggs from the ovaries of the sow, during the heat period. It is usually considered that 20 to 30 ova are shed over a period of 30 to 36 hours from the first onset of heat, by a sow that is in good condition for breeding. The actual onset of heat and the number of eggs produced during oestrum, are determined, in the sow, as in every other animal, the amount of improvement that ds taking place in the animal at that time. This improvement is commonly spoketf of as “flushing.” In the sow this flushing automatically takes place immediately after'weaning, and is due to the re-absorption of milk from the udder back into the sow’s body. It is probably because of this automatic flushing that oestrum occurs so regularly within three to six days of weaning. It is also prob.-, ably true that where the first heat period is missed and djfliculty is subsequently experienced in' getting a sow in pig, this difficulty is because of the absence of fiusfiing.

Treatment of the Sow at Weaning.

Many owners, at weaning, turn the sow out on a bare paddock and reduce her feed supply, and even let her back to the litter once a day, so as to dry her off. If the sow is in high condition this may be all right, but if the sow is in low condition tys treatment may result in delayed oestrum or the shedding of few eggs, and a small litter following. Where sows fail to come on heat after weaning, they should be shut up and fed heavily, fop a week before the next heat period is due. On the other hand where maiden sows are < in such high condition that they are incapable of rapid improvement at he onset of oestrum, small litters often result, and this can be prevented by keeping the bow always in good condition', but somewhere below the peak of her form. Time of Boar Service. It'was mentioned above that 20 .to 30 ova may be shed over a period of 30 to 36 hours from the time the sow first comes on heat. These eggs are shed one at a time, and if service takes place when only a few eggs are shed, then only a few will be fertilised and a small litter will resuit. The sperm of the male remains active on the uterus for about 8 to 10 hours, so that if servljce takes place at 24 hours after heat begins all eggs shed up to 32 to 34 hours may be fertilised. If these points are appreciated the sow will be served ideally, that is with every prospect of a big litter, about 24 to 36 hoqrs after she comes on heat. In practice the best thing is probably to give one service when the sow is well on heat, and a second one as late as the sow will stand service. Treatment During Gestation. If the owner has attended to these points he has laid the foundation for a big litter, and provided the sow is reasonably treated for the next four months, he should not be disappointed, Experimental work at Cambridge

University some years ago on in-pig sows showed that a few days after service a sow’s uterus showed the implantation of 20 fertilied living embryo with a corresponding number of ‘.‘corpora lutea” in the ovaries. A month after service there were again found the implantations of 20 fertilised embryo, and corresponding corpora lutea, but only 16 to 18 of rhe embryo were alive. Two months after service the evidence of 20 implantations was found, but only 1416 of the embryo were alive. Two months after service only 10 to 12 foetuses were found, and at four months 10 to 12 pigs were farrowed, [n all about 50 sows were slaughtered in collecting this information, and at the different killing stages it was found that on the average the same number of eggs were fertilised per sow, but that as the months went by the number surviving got less and less till only half the number fertilised were born alive. At birth while an average of 10 live pigs were produced, some sows produced dead pigs, some weakly ones that died after birth and some of course produced litters of even-sized pigs. Causes of Foetal ;Mortality. The explanation of the observed happenings appears to be that a sow sets out to produce a maximum number of offspring, but finds as time goes on that she cannot maintain her original intention, and by restricting the blood supply to any foetus, stops its development, once the blood supply is cut off the foetus ceases to live and if time permits, it is absorbed back into the maternal system. If the blood stream has been cut off late in the gestation period the little one may be born dead, absorption having been impossible in a short time. If the blood supply has only been restricted the pig may be undeveloped, weakly or undersized, and may survive to be the runt of the litter.