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(627) It is beyond the scope of this book to discuss nutrition in detail, but you should keep in mind that the quality of the feeds and the way in which they are fed are important in the management of disease. Aspects relating to nutrition in the lactating sow are dealt with in chapter 8 Nutrition. In the dry sow on the day of weaning three quarters of the daily lactation feed should be given prior to actual removal of the sow from the farrowing house and the remainder given later on that day. The sow should be given the opportunity to eat the same amount of food on the three days post weaning as she ate during late lactation. This will ensure that she does not become catabolic (a negative energy state) with an extended weaning to mating interval and subsequent infertility. Such diets should contain at least 14MJ DE/kg 16 % protein and 1.0 - 1.1% lysine, particularly if a lean genotype is being used. Immediately after mating, feed levels should be held at 2kg for the first 48 to 72 hours and then the sow fed to body condition. Provided energy levels are not excessive in the first 3 days post-mating then it is advantageous to feed the sow to body condition using a dry sow ration over the next 21 days with 3kg or more per day.

Many farms today feed separate lactating and dry sow rations. The latter with digestible energy ranging from 13 to 13.6MJ DE/kg and protein levels of 13 to 14%. It is beneficial from 3-21 days post mating to optimise feed intake relative to the sows demand since this will satisfy the nutritional requirements for the development of the placenta. This is pertinent where farms have variable weights and quality of piglets at birth. The development of the placenta in the first 12 to 25 days post mating helps to determine the quality of the piglet at the end of the pregnancy. A small placenta will contribute towards a small pig. The availability and intake of feed in this respect is important, for example where sows are fed in groups. If there is a shortage of trough space, nutritional insufficiencies can occur in the under-privileged females. During the pregnancy period the sow should be fed to body condition but also to satisfy the environmental needs. Thus it is difficult to lay down specific levels of feed intake per day, they must be determined by the stockperson. The body condition of the sow can be assessed on a numerical rating of 1 to 5 and to do this the flat of the hand should be placed over the back bone just forward of the root of the tail and rolled laterally side to side. The condition of the sow can then be scored Fig.14-16.

As a guideline sows approaching the point of weaning should score around 3. This should rise to 3 1/2 or possibly 4 in older sows by the time of the next farrowing. Sows scoring 2 1/2 or less are moving into a problem area. If more than 5% of sows at any one time score 2 1/2 or less then feeding levels are wrong. If sows are allowed to farrow with a score of less than 3 there will be insufficient fat reserves to maintain lactation and they will use muscle as a source of energy. Such sows are then in danger of developing the thin sow syndrome, being unable to maintain body condition with the demands of lactation.

In outdoor herds it is important that all sows should score over 3 before the onset of winter. It is difficult to improve body condition in cold weather. Feed levels should be higher during winter than in spring or summer.

Key points to maintaining longevity in the breeding female

  • Use the correct female, that is, one expressing maximum hybrid vigour.
  • Select or purchase females with sound strong legs, good teats and not too heavy hams.
  • Avoid gilts showing any signs of leg weakness e.g., standing on their toes, the back legs tucked under, the front legs bent or the pasterns dropped.
  • Do not breed from a female that is too lean. Maintain at least 17mm of fat at the P2 measurement by point of mating, particularly in the gilt.
  • Do not serve the gilt at less then 210 days of age. Gilts served too early will still be maturing into their second pregnancy. Equally do not serve too late (240 days) otherwise body size will increase.
  • Do not allow excessive body weight to develop during the first pregnancy.
  • Provide the pregnant gilt with exercise during the first half of the pregnancy if possible.
  • Avoid mouldy feeds.
  • Do not cull a sow if her first two litters have been poor. Review management procedures.
  • Feed the sow from three days post farrowing, during lactation, and to point of mating to appetite.
  • Do not serve maiden gilts or first litter gilts with heavy boars. This can precipitate leg problems.
  • Identify sick or lame sows early and remove to a well bedded hospital pen. Many will simply recover in a better environment.
  • Good nutrition is vital.
Remember that management, feeding, housing design and a comfortable well lit environment are under your control and they will have a major effect on the viability, health and production of the sow.

Key points to maximising reproduction

The pregnant animal

  • Feed to appetite from weaning to oestrus. Use the lactating diet.
  • The same amount of food eaten on the day prior to weaning should be eaten on days 1, 2 and 3 after weaning.
  • For 2 days post-service feed less than 2kg per animal where feasible. 25-30MJ DE per day.
  • Feed to body condition to 21 days post-service.
  • Increase energy intake by 0.5-0.75kg of extra feed in the last month of pregnancy but assess this in relation to possible reduced appetite in lactation and the development of udder oedema.
  • A negative energy status in the latter part of pregnancy is a major contributory factor to abortion. Always increase feed levels if the environmental temperatures are prone to fluctuation or when there are periods of low external temperatures.
The lactating animal
  • Always feed a high energy (>14MJ DE/kg) and high lysine (>1%) ration.
  • Intake should be at least 85MJ DE per day and preferably 100, according to the body size.
  • Feed to appetite from day three post farrowing.
  • Treat sows as individuals, their appetites vary considerably.
  • The more dense diet will provide more energy and nutrients to the low appetite animal - invariably this is one that will have subsequent poor reproductive performance.
  • Aim to maximise feed intake to maintain body weight.
  • The first litter female is a particular problem because feed intake is often low. Consider feeding a grower or weaner ration as part of the diet. Where a herd has been repopulated consider a special diet for the first litter female.
The gilt
The health status and nutrition of the gilt is very important in deciding whether she will come into oestrus or not. Look at the group of gilts. Are they a good weight for age, or is growth variable or poor? If this is the case is there any clinical evidence of disease, mange for example, which may be responsible for anoestrus. Active respiratory diseases, or previous pneumonia, heart sac infection or pleurisy can inhibit puberty and the onset of oestrus. Atrophic rhinitis can destroy the sensitivity of the nose and therefore the response to pheromones (male hormones). If gilts are regularly moved into continually populated pens, heavy parasite burdens and coccidia can build up that can interfere with the digestive process. Anoestrus problems have been associated with these.

Checklists for the health of your gilts

  • Assess the health and disease. Do you have:
  • Variable growth.
  • Coughing.
  • Evidence of rhinitis.
  • Mange.
  • Pneumonia.
  • Lameness and stiffness on movement.
  • Failure of the gilt to stand to the boar - Osteochondrosis or leg weakness.
  • Failure of acclimatisation.
  • Poor feed intake or an incorrect diet.
Provide good nutrition
The methods of feeding the gilt and the composition of the diet will depend on the genotype. They will also depend on the environmental needs of the gilt relative to housing, temperature and insulation of the buildings. To determine the best system requires a degree of trial and error on the farm - the objective being to produce the second or third oestrus cycle within a predetermined time span so that the service programme can be satisfied.

Key points to success:

  • Gilts should arrive on the farm at approximately 85kg and be fed a dry sow diet until 100kg. This will also allow time for acclimatisation.
  • It is necessary to increase backfat in the modern genotype to 18-20mm at the P2 measurement. This is best carried out feeding a low lysine ration, such as that contained in a sow breeder ration (13.4MJ DE/kg and 0.8% lysine). Feed to appetite.
  • Approximately 2-3 weeks prior to moving into the service area for mating ad lib feeding should take place. This is to maximise ovulation rate. Use a good lactator or grower diet containing 14MJ DE/kg and 1% lysine.
  • Low protein, low energy, or poor quality diets in the period leading up to puberty will often produce a deep state of anoestrus that in some cases is permanent. Assess the response to the diet used.
  • Do not leave gilts in a finisher house to point of service, many will never cycle and nutritional requirements may not be satisfied.

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