Does a higher quality diet post-weaning translate into better overall performance?

Monday, August 5, 2013

A study by the Prairie Swine Centre in Saskatoon suggests that it does not, but more research is needed to see if simple, cheaper diets affect the ability of the young pig to respond to disease and/or environmental stressors

by DENISE BEAULIEU and JANICE SHEA

Average litter size on swine farms in Canada has increased from approximately 12.3 to 13.7 piglets in the past five years. Further improvement is expected and is an important determinant of the competitiveness of the industry in Western Canada.

However, research conducted at Prairie Swine Centre Inc. showed that as litter size increased from 8.4 to 15.4 pigs born alive average birth weight decreased by approximately 250 grams, or almost 40 grams per additional pig. The number of pigs less than 850 grams increased from 0.2 per litter in the small litters (five to 12 piglets) to almost one per litter in the largest (16 or more born alive). As litter size continues to increase, it is crucial that these small pigs survive and go to market or the benefits of larger litters will not be realized.

The period immediately post-weaning is characterized by problems such as low feed consumption, poor growth rate and increased incidence of diarrhea in the piglets. Reducing the interval between weaning and resumption of feed consumption can mitigate these issues, thus the piglet must be encouraged to begin consuming solid feed upon entering the nursery. Traditionally, the feed offered immediately post-weaning is very high quality, containing animal by-products providing the piglet with "extra-nutritional" benefits, including appetite stimulation. This feed, however, is very expensive and producers are questioning if it is necessary for all piglets.

This experiment was designed to determine if the requirement for a complex, dense feed immediately post-weaning is dependent on the weaning weight of the pig. We hypothesized that the lightweight pigs at weaning would show a greater response to the higher quality feed. We also studied whether the provision of creep feed was beneficial.

Fifteen nursery fills were studied. Each nursery (32 pens, four to five pigs per pen) was filled with the piglets from one week's farrowing. We used only 12 pens, six for the lightest and six for the heaviest pigs from the weaning group. Within each body-weight grouping, these six pens were then assigned to one of three treatments (Table 1).

Thus, within each nursery we had two pens per treatment, per body-weight grouping. Pens were mixed gender, and contained at least two pigs of each gender. Farrowing groups one to eight received creep feed (a non-medicated phase one starter) for one week prior to weaning. Groups nine to 15 received no creep feed. As described in our earlier report (Fall 2011), creep feeding in this experiment did not improve average litter weaning weights.

Diets (Table 2) were formulated to meet or exceed amino acid, energy, vitamin and mineral requirements for pigs of this age and body weight (NRC 1998). The "complex" diet used corn instead of corn Dried Distillers Grains with Solubles (DDGS) and contained whey, plasma, blood meal and fish meal, while the "simple" diet met requirements using wheat, soybean meal, canola meal and corn DDGS. The simple diet would thus be much "cheaper" to manufacture.

While both diets met all the nutrient requirements for piglets of this age and weight, ingredients in the complex diet should supply additional benefits, such as improved palatability and help for the immune system. We hypothesized that the complex diet would be especially beneficial for lightweight piglets and those who had not received creep in the farrowing room. As shown in Table 2, based on August 2012 ingredient prices, the complex diet cost $906 per tonne or $400 more than the simple diet.

The three treatments were: A, the complex diet only on day 1; B, the complex diet on the first four days, followed by the simple diet; and, C, just the simple diet. Surprisingly, dietary regime had no effect on piglet performance during the first 14 days in the nursery (Table 3). The provision of the complex feed improved feed intake and prevented some body-weight loss during the first 24 hours post-weaning; however, this benefit was not maintained.

There was an interaction between diet and body-weight category on growth rate immediately post-weaning (Figure 1). Piglets which were heavier at weaning lost weight during the first day post-weaning, regardless of diet complexity. In contrast, piglets which were lighter, and receiving a complex diet, maintained their body weight.

Our hypothesis that lightweight pigs would respond more to a higher quality diet was proven correct for the first 24 hours post-weaning. However, overall, this response appears to be of little importance as there were no interactions of birth weight and feeding regime after this time (data not shown).

In this experiment, feeding a simple diet, formulated to meet all nutrient requirements, did not reduce growth of piglets when compared to a complex diet fed for one or four days post-weaning. Switching from a complex to a simple diet after one day reduced feed intake to a greater extent than switching after four days post-weaning. Feeding the complex diet for the initial four days in the nursery would cost about $0.50 more per pig than feeding the simpler, cheaper diet throughout.

Our results indicate that these savings would accrue regardless of piglet birth weight. It is important to note that these studies were designed specifically to investigate the response to the diets and these pigs were raised under ideal, non-stressful conditions. We are presently conducting experiments to determine if these results will be maintained when pigs are raised under more commercial conditions.

In a similar experiment in 2012, however, postdoctoral fellow Crystal Lévésque and co-workers at the University of Guelph showed that, although pigs fed a simple diet post-weaning did have decreased growth and feed intake relative to their cohorts receiving a complex diet, they compensated for this reduction during the grow-finish stage. Thus, there was no overall effect on performance, but overall, a decrease in lifetime diet cost.

The bottom line is that producers may be able to save money by feeding simpler stage one diets. However, our study and that conducted at the University of Guelph indicate that further research is required to determine if these simple, cheaper diets affect the ability of the young pig to respond to disease and/or environmental stressors.

Strategic funding for this research was provided by Saskatchewan Pork, Alberta Pork, Manitoba Pork Council and the Saskatchewan Ministry of Agriculture, Agriculture Development Fund. BP

Denise Beaulieu and Janice Shea are researchers at the Prairie Swine Centre in Saskatoon.