If this happens, milk production declines and conditioning is lost as fat reserves are mobilized to synthesize milk. This loss of fat and accompanying loss of protein mass both affect reproductive performance. The sows weaning to rebreeding interval will be extended, and farrowing rate and subsequent litter size is also challenged as the number of eggs ovulated decreases. The effect of decreased feed intake on the sows’ litter is also important. There is a direct correlation of feed intake and piglet performance. As feed intake increases, milk production rises, increasing piglet growth rates. A sow that is milking well should also have decreased pre-weaning mortality rates.

There are a number of things that can be done to ensure that sows will be consuming sufficient feed to avoid excessive weight loss during lactation:

Under normal commercial conditions it is unlikely that gestation feed levels will influence litter size unless feed intake is restricted significantly reducing ovulation rate and subsequent embryo survival. Targets for weight gain in gestation should be based on backfat at the time of weaning and her weight at weaning.

• Sows at all parities should have 18-20 mm backfat at the time of farrowing. Sows should be fed an extra 1 kg of feed at day 100 from breeding.
  
  

• It is important that an adequate amount of fresh feed is kept before lactating sows at all times in adequately designed feeders that do not restrict feed intake.
  
  

• Stockman should be aggressive in getting sows onto full feed as quickly as possible especially for the shorter lactation periods now common in our industry
  
  

• It has also been shown that protein content and quality of lactation diet may influence feed intake. Sows eating diets containing 12-14% crude protein ate less than sows consuming diets of 16-18% crude protein. Increased protein levels also had the effect of increase piglet weaning weights. Protein concentration in the diet also affects conception rates and days to heat post-weaning.
  
  

• The type of diet is also shown to have an effect on total feed consumed. Pelleted diets increase feed intake due to a reduced amount of feed spillage. It has also been shown the wet feed is more readily consumed than dry feed. Mounting the nipple drinker over the feeder may stimulate feed intake. Water management during lactation should ensure a flow rate of 2 L/minute from easily accessible drinkers. It is important to note however that wet feed should be removed regularly to ensure a clean supply of feed free from fermentation and or molds.
  
  

• Environment will also play a part in feed consumption while sows are in the farrowing rooms. It is important to ensure that a warm microenvironment is available for piglets while the room, as a whole, is kept at a temperature low enough to ensure proper feed intake for the sow. Higher temperatures for a couple of days pre and post farrowing is required for the sow and piglets at this vulnerable time. After this, the temperature of the room should be dropped to 18.5 -19.5 degrees Celsius. Proper ventilation rates ensuring an adequate supply of clean fresh air is also required.
  
  

• It has also been shown that increasing the number of daylight hours to 16 hours in comparison to 8 hours in the farrowing room, will increase feed intake, improve rebreeding performance, and result in higher weaning weights at 21 days of age.

Large differences in sow productivity exist from one management system to another and this may in fact be due to a large extent on feed and feeding programs over a sow’s reproductive lifetime. Proper feeding during gestation conditions the sow and enables her to manage feed intake during lactation resulting in a larger number of high weight piglets being weaned. Feed intake during lactation along with proper health care, and environment will also improve reproductive performance in subsequent litters, when considering farrowing rate and numbers born alive.

Source - Prairie Swine Centre - January 2004