Pellets can be made of different lengths, diameters and degrees of hardness. The ingredients in the diet will influence pellet hardness and quality. Various studies suggest a 3-6% improvement in growth rate and feed efficiency when pigs are fed pelleted diets compared to a meal. The benefit appears to result from less feed wastage and the ability to use ingredients with smaller particle size.

Pelleting appears to improve the nutritional value of high-fiber feed ingredients to a greater extent than that of low-fiber ingredients. This may be a result of increasing the bulk density of the feed. As with any feed processing method, the increased cost must be offset by the improved feed efficiency of pigs fed the pelleted diet.

We are not aware of any data indicating that pelleting influences variation in growth rate.

Although great strides have been made in managing the environment in barns, seasonal variation in growth rate remains a major obstacle within a production system. Pigs placed in the late summer through the early winter months grow faster than pigs placed in late winter and spring months (Figure 1). As a result, market weights are reduced by 6 to 13 lb. for pigs marketed in June through mid-September. Market price is normally highest during this same time period.

Select on Figure 1 to enlarge

For many production systems, 75 to 80% of the net profit for the year is derived during these summer months. The most profitable systems have determined methods to maintain market weights through the summer months. The only way that weights can be maintained is by increasing growth rate for groups of pigs finished during this time or by increasing days in the barn.

Growth rate can be increased by one of two main feeding interventions. First, increase the energy density of the diet during summer months or for newly placed groups that will be marketed during the summer and early fall. Second, optimize ractopamine (Paylean) use by season of the year to assist in making market weights more uniform throughout the year.

Because the response to ractopamine is consistent for pigs at various weights, it can also be used to increase the growth rate of the lightest pigs in the group to make them grow similar to the heaviest pigs. This is especially important during the summer months to maximize average daily gain of both the fastest and the slowest-growing pigs. In winter months, more emphasis is placed on slowest-growing pigs, as the growth rate of the entire group is higher.

The difference between feeding ractopamine and increasing energy density of the diet is that feeding ractopamine is often economical regardless of whether the weight gain is needed or not. The economic value of feeding ractopamine is much greater in pigs that require the extra weight gain; however, the improvements in feed efficiency and carcass parameters (loin depth and yield) usually make it economical to feed to heavy pigs also. Thus, if ractopamine were only fed to the light pigs in the group, the potential increase in profit on the heavy pigs would be lost.

If dietary energy is already at the economic maximum and ractopamine is already being used, pigs must be given more days to grow to achieve the same market weight in the summer due to the lower seasonal growth rate. Finding extra days is not easy, but the production system needs to be built with this flexibility.

For example, wean-to-finish barns offer flexibility, as they can be double- or triple-stocked in the summer months to allow pigs in other barns more time before the facility is needed.

Similarly, heavier stocking density in nurseries in summer months reduces the finishing barn requirements. Heavier stocking density will reduce growth rate of these pigs; however, they will be marketed during the winter months when space is normally not a problem.

As with all areas of production, clean, fresh water should be made available to pigs at all times. While this suggestion seems simple, it can be a source of concern if no one is paying attention to the pigs' water needs.

Groups of pigs with insufficient access to water will have more variation. Plugged nipples, poorly designed water troughs or incomplete filling of gestation barn troughs caused by feed blockage can cause restricted water supply. Standard operating procedures on a farm should ensure that all pigs have proper access to feed and water.