Title: Evaluating the Impact Under Commercial Conditions of Increasing Diet Tallow Content and Dietary Energy Concentration on Grow-Finish Performance, Carcass Quality and Return Over Feed Cost

Principle Investigator: John Patience

Year: 2004

Objective: The objectives of this experiment were:
1. To determine the response of growing and finishing pigs to increasing dietary energy concentration on a commercial farm.

2. To determine the most efficacious energy level that can be adopted in diets for growing and finishing swine housed in a commercial facility based on performance, carcass composition and return over feed.
3. To determine if increasing dietary energy concentration will help to reduce variation in pig performance, by allowing pigs with poor appetites to grow at rates closer to their higher appetite counterparts.
4. To improve the net income of pork producers through the development of feeding programs that best balance cost of feed and gross income per pig.

Lay Summary/Industry Summary: Energy is the most expensive nutrient in the diet of the pig, and yet, our understanding of energy metabolism, and more specifically, how the pig responds to changes in dietary energy concentration, is surprisingly limited. This experiment was conducted as a follow-up to a previous experiment conducted at the Prairie Swine Centre, which showed that pigs are able to achieve equivalent performance across diets of quite differing energy concentration. These results flew in the face of conventional wisdom, which suggests that increasing dietary energy concentration, notably through the additional of fat, will result in faster growth. This experiment was therefore conducted to re-evaluate this question, and determine if increasing dietary energy concentration would improve pig performance. The experiment was also designed to evaluate the impact of dietary energy concentration on carcass quality and on the uniformity of growth. The authors wondered if the level of feed intake of the pigs would impact on the response to energy, so a commercial farm was used; with a lower feed intake, it was considered a good model to evaluate the response of pigs to dietary energy concentration.

Experimental diets were formulated in a practical manner, such that energy concentration was elevated by using less barley and increasing amounts of wheat, soybean meal and tallow. The lowest energy diets contained 0.5% tallow and the highest energy diets contained 4% tallow. The actual DE content of the diets was determined by collecting faecal samples at the mid-point of each phase. On this basis, the mean dietary DE concentrations were 3.12 Meal/kg (3.20), 3.30 Meal/kg (3.35) and 3.43 Meal/kg (3.50); values in parenthesis were the formulated DE targets.

Pigs performed very well on this experiment, with daily gain averaging 990 g/d across treatment. The higher energy diet supported higher weights up to first pull (P<0.05), but of course, market weights were constant across treatments because pigs were weighed prior to marketing to ensure they would fall within the packer’s desired weight range. Average daily gain and feed efficiency were improved during the early phases of the experiment, up to about 80 kg (P<0.05); up to this point, there was no effect of diet on average daily feed (P>0.10), so increased dietary energy concentration resulted in increased daily energy intake (P<0.05). However, beyond about 80 kg, pigs tended to consume less of the higher energy diets, so growth rate was not affected by diet during this period. Of particular interest to commercial barn operators was the observation that the number of tail-end pigs, those that did not achieve the target shipping weight within the room tum period, was higher on the lower energy diets. We therefore concluded that higher energy diets make the most sense during the growout period below 80 kg, but not above 80 kg. Interestingly, there were more pulls during the growout period on the higher energy diet, due either to mortality or serious health problems (prolapse, tail-biting, etc.). Thus, the portion of pulls was 3.75% on the two lower energy programs, and 5.4% on the highest energy program. If this observation is real, it has a significant impact on the economic value of the higher energy program. Dietary energy did not affect carcass backfat thickness, lean yield, carcass index or carcass value (P>0.10). However, the higher energy diets tended to increase loin thickness (P<0.10), something we have seen in previous experiments. The dressing percentage of the pigs on the low energy diet tended to be lower than pigs on the other treatments (P<0.10).

The dietary energy concentration did not improve the uniformity of the pigs, nor the uniformity of their carcasses. Thus, producer should not increase diet energy concentration with the expectation that pigs will reach market in a more uniform manner, or produce more uniform carcasses. The latter will be much more dependent on selection practices at the time of shipping.

The economic analysis was conducted using longer-term average prices for pigs (1.451kg) and ingredients: (wheat, $130/t; barley, $110/t; soybean meal, $340/t; canola meal, $204/t) were employed. A price of $550/t for tallow, obtained from Saskatoon Processing, was also used.

The published Olyrnel (West) grid was applied to determine the value of pigs. Two possible scenarios for the adoption of these results on a commercial farm were considered. In scenario #1, pigs were shipped at the time the finishing room was turned over to the next group, and revenues reflected the associated lost value. Under this circumstance, the best return over growout feed cost was earned on the lowest energy diet, with an advantage in the range of $2.12 compared to the medium energy program, and $4.04 over the high energy program. In the second scenario, the tail-end pigs were held back until they reached the minimum market weight; this resulted in a higher gross income, since all pigs would be marketed within the optimum weight range, but the cost would be higher, since there would a considerable increase in the feed required. In this scenario, the advantage again fell to the lowest energy program, earning $1.26 more than the medium energy program, and $4.02 compared to the high energy program. In the latter scenario, no charge for housing was included, as it was assumed that hold-back pigs would be moved into an existing hold-back room, or would be placed with other pigs. However, a substantial feed penalty was applied to the hold-back pigs, an amount which we suspect is very conservative. We understand this scenario would not applied universally, but it is impossible to conducted an economic analysis that applies to all possible commercial circumstances. Sufficient information is presented herein to allow individual pork producers to conduct their own economic analysis. Of course, the results of the economic analysis could change if differing packer settlement agreements were applied.

In conclusion, net income can be maximized by feeding lower energy programs. However, the results of individual phases within this experiment suggest that feeding higher energy diets up to 80 kg may be warranted, as this is the period when pigs would respond the most to the higher energy diets.

It is clear from this experiment, and from others conducted previously, that the response to dietary energy concentration is not easy to predict. We suspect, based on biology and not on experimental data, that the response of a group of pigs to dietary energy concentration may be determined by their normal feed intake. If pigs are able to consume sufficient quantities of feed to achieve excellent growth on lower energy diets, then feeding higher energy diets is unlikely to be beneficial. However, if feed intake is low, then there may be a benefit to feeding higher energy diets, to increase daily energy intake and thus support faster growth. Nonetheless, we caution producers from assuming that increasing dietary energy will universally increase pig performance; experimental data does not support such an assumption.

Finally, the deviation we observed between formulated DE values and determined DE values in the experimental diets confirms the importance of this measurement. The average deviation reported herein was 71 kcal/kg, or 2.1%, a significant amount in the context of practical swine diet formulation.

Evaluating the Impact Under Commercial Conditions of Increasing Diet Tallow Content and Dietary Energy Concentration on Grow-Finish Performance, Carcass Quality and Return Over Feed Cost

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