Pork producers and nutritionists want to use feed ingredients that will optimize pig performance at the lowest cost. Inclusion of DDGS in the diets for grower-finisher pigs may be economical at certain times, but not at other times. So, this puts the producer in the position of weighing the economic benefits of suddenly including economically priced DDGS in diets against any potential reductions in pig performance. We have very little direct evidence of the pig’s response to frequent inclusion and removal of DDGS from the diet. If there are no changes in pig performance when switching between DDGS and non-DDGS diets, more pork producers may include DDGS in diets when it is economical, knowing that switching between DDGS and non-DDGS diets will not result in any reduction in pig performance.
The pig’s feed intake response to DDGS in the diet is puzzling. Recently, researchers at the Universities of Illinois and Minnesota summarized 23 published studies reporting performance responses of growing-finishing pigs when their diets contained up to 30% DDGS. Average daily feed intake was increased in two experiments, reduced in 6 experiments, and not affected in 15 experiments when DDGS diets were fed. The reasons for this variable feed intake response to DDGS are unclear. There is limited evidence suggesting that alternating between DDGS and non-DDGS diets could decrease feed intake in growing-finishing pigs. Researchers at Kansas State University found that pigs preferred a corn-soybean meal diet over one containing DDGS when offered a side-by-side choice. However, the pigs’ preference for the corn-soybean meal diet does not necessarily mean that feed intake and growth rate will be reduced if pigs are only offered a DDGS-containing diet. Other researchers have shown that a reduction in feed intake may occur when switching to bulky ingredients with high fiber content. Consequently, our research group conducted an experiment to determine the effects of switching between corn-soybean meal and corn-soybean meal-DDGS diets on pig performance and carcass quality of finishing pigs.
Two hundred sixteen pigs were housed in one of 24 pens and assigned to one of 4 dietary treatments. Dietary treatments consisted of a corn-soybean meal control (D0), a corn-soybean meal diet containing 20% DDGS fed throughout the study (D20), D20 and D0 diets alternated bi-weekly (D20SW), and a 40% DDGS diet alternated bi-weekly with the D0 diet (D40SW). There were five two-week feeding periods with pigs assigned to D20SW and D40SW treatments starting and ending the trial consuming DDGS diets. Pigs were fed corn-soybean meal diets until the experiment started when pigs weighed about 110 lbs. Dietary treatments had no effect on average daily weight gain. With the exception of feed efficiency, growth performance was not different among pigs fed the control diet continuously, the 20% DDGS continuously or the 20% DDGS and control diets in an alternating pattern. For some reason, pigs fed the 20% DDGS diet continuously were not as efficient as those fed the same diet alternated with the control diet. Pigs switched on and off a 40% DDGS diet were lighter at the end of the 70-day study and produced a lighter carcass than pigs assigned to the other treatments because they tended to consume less feed. Dressing percentage and carcass fat-free lean percentage were not affected by dietary treatments.
Results of this study suggest that the frequent inclusion and removal of 20% DDGS from diets for finishing pigs will not adversely affect pig performance or carcass characteristics. We plan to conduct a similar experiment to determine if consistent responses are observed with lighter pigs. It appears that alternating 40% DDGS in and out of the diet may reduce feed intake and hot carcass weight of finishing pigs.
