Our first study evaluated diets containing 50% DDGS in gestation and 20% DDGS in lactation. This study demonstrated that 50% DDGS in gestation diets supported sow performance equal to a corn-soybean meal control diet. Including 20% DDGS in the lactation diet supported performance equal to the control diet. However, sows should be transitioned onto a high DDGS diet gradually to allow time for them to adapt to the new diet.

A more recent study, completed in 2006, investigated inclusion of up to 30% DDGS in diets for lactating sows. Up to 30% DDGS in the diet supported lactation performance that equaled that of sows fed the corn-soybean meal control diet (Table 5).

Production of ethanol does not destroy mycotoxins that might be present in the source corn, but rather concentrates them by a factor of three. This has raised concerns among nutritionists and pork producers.

However, there seems to be only a small risk of mycotoxin contamination of DDGS because most ethanol plants screen incoming corn for quality and reject moldy, off-quality grain. Producers need to work with their DDGS supplier to ensure mycotoxins are not a problem in the DDGS product being fed.

Currently, it appears that producers can include up to 50% DDGS in gestation diets and 30% in lactation diets without negatively affecting sow performance.

The drive to use more biofuels has bolstered interest in biodiesel. In the production of biodiesel, a variety of fats are mixed with methanol and a catalyst to strip the fatty acids from the glycerin. The fatty acids are used in biodiesel and the glycerin is left for other uses.

Soybean oil is the predominant fat being used for biodiesel production, but other fats can also be used. Glycerin can be incorporated in swine diets as an energy source.

Early studies with nursery and grow-finish pigs suggest glycerin has an energy value very similar to corn. Crude glycerin may contain high levels of methanol and salt, which need to be considered in diet formulations. But at high inclusion rates, feed may not flow easily through commercial handling and feeding equipment. The value of glycerin in sow diets has not yet been determined. The swine nutrition research group at the University of Minnesota is currently studying the use of crude glycerin in lactating sow diets.

Societal concerns for the welfare of limit-fed gestating sows have led some to consider high-fiber diets for pregnant sows. Limit-feeding gestating sows to control weight gain can lead to stereotypic, repetitive behaviors that some people equate to compromised welfare.

European researchers have significantly reduced expression of these behaviors with very high (over 45%) inclusion rates of fibrous feedstuffs, such as sugar beet pulp, oat hulls, wheat bran and others. These results suggest that pregnant sows may have a behavioral requirement that high-fiber diets can satisfy without making them fat.

Unfortunately, diets that successfully control stereotypical behaviors do not flow well in U.S. feeding systems. We were not successful in decreasing these undesirable behaviors when sows were fed a diet containing 40% soy hulls that did flow through a commercial feed handling system. Future research will determine how best to utilize fiber in sow diets under U.S. conditions.

Take-Home Message

Feeding the sow herd is a complex venture that requires consideration of numerous factors. Attention to detail throughout the feeding program is important for success. Proper feeding during gestation and lactation sets the stage for optimal performance in subsequent phases of the reproductive cycle.

All sow herds are not alike. Producers must be open to new ideas and evaluate nutrition and management approaches that make economic sense in their herds.

Table 1. Influence of Automatic Feeding System for Lactating Sows

Trait	Hand-fed	Self-fed
Feed intake, lb./day	11.9	13.0
Sow weight change, lb.	1.3	13.7
Pig weaning weight, lb.	13.5	14.6
Peng et al. (2007)

Table 2. Effect of Water Flow Rate on Feed Intake and Weight Loss of Sows Through Day 21 of Lactation

	Winter		Summer
	Water flow rate (cups/min.)
Item	3	0.3	3	0.3
Feed intake, lb./day	11.3	9.3	8.9	8.0
Sow weight loss, lb.	11.6	31.0	30.5	46.3
Leibbrandt et al. (2001)

Table 3. Recommended Water Quality Standards for Breeding Swine

Trait	Recommended Maximum
Total dissolved solids	<5,000 ppm
Nitrate N + Nitrite N	<440 ppm
Nitrite N	<33 ppm
Total coliforms	<50 per ml
NRC (1998); EPA (1973)

Table 4. Attributes to Consider in Selecting Alternative Feed Ingredients

Nutrient profile	Cost per unit of nutrient supplied
Presence of anti-nutritional factors	Ease of handling
Presence of toxic compounds	Digestibility of nutrients
Palatability	Availability
Consistency

Table 5. Performance of Lactating Sows Fed Distiller's Dried Grains with Solubles (DDGS)

Dietary DDGS (%)
Trait	0	10	20	30
Sow feed intake, lb./day	14.3	14.5	15.4	14.7
Litter size weaned	9.7	9.6	9.9	9.8
Litter weight gain, lb.	100.3	103.3	103.1	100.4
Song (2007)