More research is needed to determine requirement estimates of these amino acids; however, results to date indicate these amino acids must be carefully considered in diet formulation to prevent costly limitations during lactation.

In practical diet formulation, formulate to meet the lysine requirement of the sow and attempt to maintain high levels of threonine, valine, isoleucine and methionine without incurring excess cost. Typically, these amino acids are formulated in ratios relative to lysine (Table 3). Monitoring these ratios is especially important when using alternative ingredients and synthetic amino acids.

An example of a corn-soybean meal-based formulation for lactating sow diets is provided in Table 4. Additionally, diet formulations with 10, 20 or 30% distiller's dried grains with solubles (DDGS) are included.

With the dramatic increase in ethanol production, DDGS has become more abundant and available for use in swine diets. Data has indicated that DDGS produced from new ethanol plants has approximately the same energy content as corn.

Initially, there was much concern over adding DDGS to lactation diets due to the reductions in palatability when added to finishing pig diets.

However, recent research has failed to indicate a similar reduction in palatability when DDGS is included in lactation diets. Therefore, it appears that high-quality DDGS can be used as an economical ingredient in lactation diets with a substantial reduction in feed cost per ton. Good indicators of high-quality DDGS are greater than 26.5% crude protein, a 2.8 lysine-to-crude protein ratio, 10.5% fat and freedom from mycotoxins.

Limitations of Added Fat

Adding fat to the lactation diet is an effective means of increasing the fat content of the milk and improving litter weaning weight, but it will not benefit sow reproductive performance. It is important to remember that dietary fat is preferentially used by the mammary gland and results in production of “high fat” milk rather than being used by the sow as an energy source.

Use of high dietary fat levels during lactation will improve litter weaning weights, but may actually impair subsequent reproductive performance by influencing reproductive hormones in early lactation. Therefore, although some added fat (up to 5%) may be beneficial to improving litter performance, high levels of added dietary fat (greater than 5%) should not be used as a remedy for poor lactation feed intake.

Producers should take all steps possible to increase lactation feed intake whether fat is added to the diet or not. Generally, if it is economical to add fat to late nursery diets, it will be economical to use 3-5% fat in the sow lactation diet.

Parity Effects

When all sows are housed in the same facility, management must choose either to provide higher amino acid levels than required by the multiparity sows in order to meet requirements of young sows, or formulate closer to the requirements of older sows and not meet the requirements of young sows.

In most situations, the choice is to formulate closer to the requirements of the young sows and oversupply nutrients to the older sows. An advantage of segregated parity flow is that old sows can be fed diets formulated closer to their nutrient requirements in gestation and lactation, resulting in reduced feed cost.

Feeding Management

Lactating sows should be full-fed in order to maximize milk production. A lactating sow will normally consume 9 to 15 lb. of feed per day. Intake level will depend on diet composition, sow's body condition, previous gestation feed intake, water availability and environmental temperature of the farrowing facilities. Consider the following procedure to maximize sow feed intake:

Sows are fed 0, 1 or 2-to- 4-lb. scoops at each of three feedings during the day. If there is feed left in the feeder from the previous meal, no feed will be added to the feeder. If a small amount of feed is left, one scoop will be added. If the feeder is empty, two scoops will be fed. Managers may want to consider the extra scoop of feed in the afternoon feeding if feeders are consistently empty in the morning at the next feeding. The only deviation from this pattern is for Day 0 to 2 after farrowing. During this time, the decision is to give 0 or one scoop at each meal to limit over-feeding while milk production is being initiated.

Many farms are implementing mechanized systems that allow for continuous access to lactation feed. One option is to use a beveled PVC pipe clamped within the feeder using U-bolts (Figure 1). The pipe is then attached to a feed line using flexible tubing with an individual shutoff over each feeder. Field observations indicate that average daily feed intake often increases from 1 to 2 lb./day after implementation of these systems.