Modern lactating sows are leaner than their contemporaries of 10 to 15 years ago and they produce large amounts of milk. They also have a larger body weight relative to age and are more immature and still growing at the times of mating, farrowing, lactating and weaning as a gilt. These females therefore have higher maintenance requirements together with reduced feed intake in lactation. These changes make it particularly difficult for the gilt to consume sufficient energy to meet the demands, of growth and maintenance, foetal growth and then milk production. As a result there may be a breakdown of body tissues (catabolism) to meet these requirements. Although mature sows are not growing, they often have larger litters and an increased demand for milk products. The following factors need to be considered when assessing gilt and sow nutrition, feed intake, production and disease.

• The breeding female should ideally not loose more than 10kgs of weight during lactation.
• Losses above this will extend the weaning to mating intervals with fewer animals in heat within 10 days of weaning. Animals that have become catabolic may have poorer farrowing rates and litter sizes.
• Low feed intake during lactation can have a significant effect in depressing subsequent reproductive performance.
• With a high feed intake body condition is maintained and milk production is increased.
• Growth rate in the piglet is maximised by converting feed into milk.
• The lean genotype female requires a high intake of lysine and the lactating ration should contain 1.1 to 1.2% lysine with a protein level of 17-18%. Energy levels should range from 14 to 14.5MJ DE/kg.
• Remember the sow is an individual and the feed intake will vary from one animal to another.
• The first litter gilt is a particular problem because it has a restricted appetite and its energy and lysine requirements are greater than those of the sow. This can be satisfied by feeding an early grower diet (up to 1.3% lysine 14.8MJ DE/kg) or giving it as half of the daily ration.
• Managing the feed intake is an art and sows from three days post-farrowing should be fed a lactation diet of the above specification to appetite but not to cause indigestion.
• Sows should be fed twice daily with sufficient amounts that are eaten within an hour and a half.
• Water flow should be a minimum of 2 litres per minute.
• There is considerable variation in feed intake between different genotypes during lactation. Manage your own herd to maximise feed intake but do not cause inappetence.
• Many sows will show a drop in their feed intake during the second and third week of lactation. This dip reduces milk production and hence weaning weights. Make sure that it is not due to inadequate or slow water supply. Recent work suggests that controlling feed intake on a set rising scale improves weaning weights. This is a contentious area however and is dependent on the diet quality. You are advised to determine your own response in this respect.
• Maximising energy and lysine intake in the first two weeks of lactation stimulates the development of the primordial follicles in the ovary and ovulation rate in the next oestrus.
• Sows prefer to eat in the early morning and late in the evening. It is debatable whether sows will eat anymore by feeding them more than twice daily.

Factors that affect feed intake during lactation

• High environmental temperatures. Above temperatures of 24ºC (75ºF) feed intake may be reduced by up to 80g per day for every increase of one degree.
• Some breeding females eat more than others.
• Sows eat more wet feed rather than dry.
• Heat lamps placed too near the sow increases the temperature.
• Low-nutrient-density high-fibre diets will reduce the availability of nutrients to the sow.
• Litter size.
• Lactation length.
• Fat depths at farrowing. If a sow has been fed too heavily for the 3 to 4 weeks pre-farrowing this will depress appetite during lactation.
• Floor surfaces. Slatted floors are cooler than solid floors. Air flow , humidity and efficiency of insulation of the house can also affect the temperature of the environment.
• Sow health - It is important to ensure that the preventative routines have been carried out, particularly worming, so that damage to the digestive tract does not impair the use of food.
• Palatability - A small pellet (5mm) is more palatable than a large one.

Nutrition during lactation is ideal if:

• Sows maintain good body condition throughout.
• Average total litter size born is 12 or more.
• The farrowing rate is 90%.
• Weaning weights at 21 days average over 6kg.

Do not make any changes if you are achieving this performance.