Today’s highly prolific Hypor sows are expected to wean large numbers of heavy piglets and require more feed to fuel that increase in productivity. Also, they have a low level of body fat, which means they have few energy reserves to draw on and therefore, if feeding is inadequate, they can rapidly deplete muscle tissue.

In order to achieve a high Weaning Capacity and maximize the weight of piglet weaned per sow lifetime, feeding programmes must meet the nutritional needs of the Hypor sow at all stages of the reproductive cycle. In particular, sow longevity will be enhanced where the lifetime feeding program allows for body growth in the sow and maintenance of the correct body condition, while achieving a high level of performance.

Gestation

In gestation, the main objective of the feeding program for Hypor sows is to regain any condition or body weight lost during lactation and to ensure that the sow reaches her subsequent farrowing in the correct condition. For gilts, prior to their first farrowing when body condition is unlikely to be an issue, feeding should allow for body weight gain without resulting in gilts being over-conditioned at farrowing. Overfeeding gilts in gestation will lead to reduced feed intake during lactation, loss of body condition, an extended wean to oestrus interval and lower second litter size. Therefore, for a gilt bred at 140 kg and farrowing at a weight of 185 kg, an average feed intake of 2.1-2.3 kg over the gestation period will usually be appropriate, depending on stage of gestation, energy density of the diet and environment.

Although the total weight of feed consumed during gestation has the biggest effect on body weight gain and performance, it is normal to partition this depending on stage of pregnancy and, for sows, body condition. Backfat depth may also be used to determine feed levels, although this requires extensive information about overall herd backfat levels in order to determine suitable targets for different stages of the breeding cycle and for each parity.

The following information is intended to provide a general guide to feed levels and the principles involved but the individual feeding program should be determined in conjunction with the farm’s nutritionist according to local conditions.

Weaning to Oestrus

The objective at this stage is to maximize feed intake in order to start the process of regaining any body weight and backfat losses in lactation. Feeding a high feed level (3.5 kg+) between weaning and breeding has been shown to increase ovulation rate and embryo survival.

Weaned sows should ideally be fed ad libitum where possible (this can be from self-feeders where sows are housed in groups) or to appetite. For sows in stalls, the use of individual bite drinkers, rather than a “river” watering system, helps to keep feed dry and fresh, leading to higher intake.

Weaned gilts, and sometimes second litter sows, will often benefit from a high protein top dressing with dextrose as an energy source. These have been shown to increase subsequent litter size, probably by increasing follicle quality.

Recently published work by Lindemann et al in the USA suggests that injecting gilts and second parity sows with vitamin A at weaning and at breeding leads to a significantly higher subsequent litter size.

Early Gestation

Immediately after breeding, feed level should be reduced from the high levels fed from weaning onwards. However, there is considerable debate about what feed intake should be in the first 21 to 28 days of gestation. Some research suggests that high feed intake during this period leads to increased embryo losses, whereas other work suggests that restricting feed intake for the first 4 days after breeding maximizes embryo survival. Recent work by Sorensen and Thorup in Denmark showed that feeding 3.8 kg/day for the first 28 days of gestation led to increased litter size.

Such relationships are complicated by the issue of sow condition in the herd because, where condition is less than ideal, farrowing rate and litter size will often be improved by increasing feed intake.

One widely used approach is to feed sows that are in good condition a basal amount of 2.2-2.3 kg and feed a higher amount, perhaps 2.5-2.8kg, to sows that are in less good condition. For today’s lean Hyp or breeding females, regaining any condition lost during lactation is more important than any effect on embryo losses. For gilts, there is more substantial evidence that a low feed intake for the first 21 days after breeding maximizes embryo survival and so they should be fed about 2.0 kg/day during this period.

Mid-Gestation

During the period 29-90 days of gestation, feed levels are usually based on parity and sow condition or backfat depth, with the aim of achieving the desired condition or fat level at farrowing. The nutritional requirement for foetal growth during this period is quite low. Specific feed scales can be developed based on factors such as dietary energy density, environment and whether these are other sources of nutrients. Assuming the feed level is set for each sow at day 28, a further measurement of body condition or backfat should be carried out at about day 56 and feed level adjusted if necessary.

Late Gestation

From about day 85-90 of gestation onwards, the foetuses start to make rapid growth and so the sow’s nutrient requirement increases.

It is recommended to provide additional feed in the latter part of gestation, typically a level of 2.8-3.0 kg for sows and 2.6-2.8 kg for gilts.

If additional feed is not given, the sow will mobilize backfat and muscle tissue for piglet growth, which is undesirable. Individual sow that are over-conditioned should receive a lower amount to avoid udder problems at farrowing. On some farms, especially those with low birth weights, this increase in feed intake may lead to higher birth weights, although the effect is usually small.

However, recent research in France suggests that increased feed levels in the last 15 days of gestation may result in easier farrowings, less stillbirths and more viable piglets at birth.

Prior to Farrowing

In the 3-4 days prior to farrowing, feed intake should be reduced to 1.8 kg/day for gilts and 2.0 kg/day for sows in order to ensure good udder condition at farrowing.

Overfeeding may lead to udder problems such as mastitis and agalactia, causing a reduction in milk supply, reduced piglet survival and lower piglet weaning weights. This condition is exacerbated when sows are in excessively good condition due to overfeeding in gestation.

Sows just prior to farrowing tend to be constipated and will benefit from the addition of high-fibre feeds such as bran. A readily available supply of fresh, clean water will also help to avoid any udder problems, so drinker flow rate should be checked as sows enter the farrowing crates. A minimum flow rate of 2 litres/minute is recommended and 3 litres/minute is ideal.

From the Beginning

Hypor has aimed its breeding programme at increased feed intake capacity but at the same time, there has been pressure for conversion efficiency. The simultaneous pressure on weaning capacity, feed efficiency and increased daily feed intake has resulted in a relatively efficient sow. Under harsher conditions such as hot or tropical climates, the Hypor sow still maintains its intake at a good level.

Focusing on litter weight gain from birth till weaning in the breeding program has helped to improve the total milk production of Hypor sows. It is clear that our future sows should be able to eat enough but should be efficient converters at the same time. At Hypor, this is part of a sustainable breeding goal that maximizes weaning capacity.

Applying the correct feeding strategy during gestation will contribute to a number of components of Weaning Capacity, including total litter size, numbers born alive, piglet growth, weaning weight, sow health and longevity.

January 2009