Nutrition advances benefit swine and the bottom line
DDGS and soybean products devoid of allergens can economically enhance diets.
It is now well accepted that distillers dried grains with solubles (DDGS) can be used in diets fed to swine in amounts of up to 30% if fed to weanling pigs from two weeks post weaning, to growing and finishing pigs, and to sows. At these inclusion levels, performance of pigs is most often not affected.
From year 2000 to the end of 2009, a total of 12 experiments in which corn DDGS was included in diets fed to weanling pigs from two weeks post-weaning were published. The inclusion of DDGS varied from 10% to 30% in these experiments and pig growth rate was not significantly reduced in any of the experiments (Table 1).
Feed intake was, however, reduced in four of the 12 experiments, which is consistent with observations indicating that pigs prefer to eat diets containing no DDGS if they have a choice. There have been no reports on negative effects of corn DDGS on pig mortality and the gain to feed ratio has been improved in five of the 12 experiments. It is, therefore concluded that if it is economical, corn DDGS can be included in diets fed to weanling pigs from two weeks post weaning in concentrations of up to 30%.
For growing-finishing pigs, data from a total of 31 experiments in which corn DDGS was included in the diets were published between year 2000 and year 2009. The inclusion of DDGS was between 10% and 30% in these experiments. Growth performance was increased in one experiment, reduced in seven experiments, and not affected by DDGS in the remaining 23 experiments (Table 2). The gain to feed ratio was improved in four experiments, reduced in six experiments, and not affected in the remaining experiments.
Iodine value increases
Dressing percentage was reduced as a consequence of inclusion of DDGS in the diets in ten of 21 experiments, but not affected in 11 experiments. It is currently not known why dressing percentage sometimes, but not always, is reduced when DDGS is included in the diets. There were no effects of DDGS on carcass composition and carcass quality in most of the experiments, but the iodine value of the fat in pigs fed DDGS was increased in eight of nine observations.
The reason for this increase is most likely that DDGS contains more than 10% fat and most of the fatty acids are unsaturated. So when pigs eat DDGS, they will deposit more unsaturated fatty acids, which in turn will result in more soft body fat, which may become a concern in the processing of these carcasses. It is, therefore, recommended that inclusion of corn DDGS in diets fed to finishing pigs should not exceed 20% during the final four weeks prior to harvest.
There has been only a few reports on the use of DDGS in diets fed to sows, but based on these experiments it is concluded that up to 50% corn DDGS may be included in diets fed to gestating sows and up to 30% corn DDGS may be included in diets fed to lactating sows. At these inclusion levels, sow and litter performance will likely not be affected.
Based on the above research, recommended inclusion levels of corn DDGS in diets fed to all groups of swine has been developed at the University of Illinois (Table 3). These inclusion levels indicate that most groups of swine can be fed up to 30% corn DDGS in their diets provided that diets are formulated in such a way that the level crude protein as well as the level of digestible amino acids is not changed.
It is, therefore, necessary to include approximately 0.10% crystalline lysine for each 10% DDGS that is included in the diets (Table 4). If more than 20% DDGS is used, it may also be necessary to include crystalline tryptophan if that is economical.
The majority of the research with DDGS has been conducted using corn DDGS, and there is limited information on the use of sorghum DDGS and wheat DDGS. There is, however, no information available that would indicate that sorghum DDGS and wheat DDGS cannot be included in diets fed to swine at the same levels as corn DDGS. However, more research is needed to confirm this hypothesis.
Eliminating inorganic phosphorus
Corn DDGS and sorghum DDGS contain between 0.6% and 0.8% phosphorus and wheat DDGS contains approximately 1% phosphorus. These concentrations of phosphorus are approximately three times greater than the concentrations in corn, sorghum, and wheat. The digestibility of phosphorus in DDGS is much greater than in corn and soybean meal and the standardized total tract digestibility of phosphorus in corn DDGS is between 60% and 80%. If DDGS is included in the diets it is, therefore, possible to reduce the inclusion of dicalcium phosphate or monocalcium phosphate as indicated in Table 4.
Inclusion of microbial phytase will further increase the standardized total tract digestibility of phosphorus in corn DDGS by five to 10 percentage units. Microbial phytase will also increase the digestibility of phosphorus from other ingredients in the diets and it is, therefore, also possible to reduce the amount of dicalcium phosphate or monocalcium phosphate in the diets by using microbial phytase.
If the combination of DDGS and phytase is used, all the phosphorus that is needed may be supplied from the vegetable ingredients in the diet, and there is no need for addition of inorganic phosphorus if the pigs are at least 11 kg or heavier (Table 5).
The growth performance of pigs fed diets containing DDGS and microbial phytase, but no dicalcium phosphate, is not different from that of pigs fed diets based on corn, soybean meal, and dicalcium phosphate. By using this formulation technique, the amount of phosphorus that is excreted from the pigs is reduced by approximately 50%, which will reduce the risk of environmental pollution when the manure is applied to agricultural fields.
Fermented or enzyme-treated soybean meal
It is common practice to include animal proteins in diets fed to weanling pigs because pigs do not tolerate soybean protein very well during the initial weeks post-weaning. They may develop allergenic reactions followed by immunological responses if they are fed large quantities of conventional soybean meal.
Fish meal is, therefore, often used in diets fed to weanling pigs despite the fact that the cost of fish meal is much greater than the cost of soybean meal. However, two new soybean products, HP 300 and PepSoyGen, respectively, that are expected to be devoid of soy allergens were recently introduced to the feed markets in the Americas. It is believed that these products can be included in diets fed to weanling pigs without causing adverse allergenic reactions.
During the production of HP 300 (Hamlet Protein, Horsens, Denmark), a proprietary enzymatic preparation is used to digest the antigens in soybean meal. The oligosaccharides and sugars in the soybean meal are also removed and the resultant soybean meal contains approximately 53% crude protein (Table 6). The digestibility of amino acids in HP 300 is greater than in conventional soybean meal and the digestibility of energy and phosphorus in HP 300 is similar to that of conventional soybean meal.
Fish meal substitutes
Experiments in Europe and Asia have indicated that inclusion of HP 300 in diets fed to weanling pigs results in pig performance that is similar to that obtained on diets using animal proteins. It is, therefore, expected that HP 300 can also be successfully used in the feeding of weanling pigs in North America and Latin America and the need for inclusion of the higher priced fish meal will, therefore be reduced.
PepSoyGen (NutraFerm, North Sioux City, SD) is produced by fermentation of soybean meal in the presence of Apergillus oryzae and Bacillus subtillis. Antigens, antinutritional factors, oligosaccharides, and sugars are removed from the soybean meal during fermentation (Table 6). PepSoyGen contains almost 10% more protein than conventional soybean meal.
The standardized ileal digestibility of amino acids in PepSoyGen is similar to the digestibility in conventional soybean meal, and the inclusion of PepSoyGen in diets fed to weanling pigs at the expense of fish meal results in no change in performance. It is, therefore, possible that PepSoyGen can be used in weanling pig diets as a substitute for more expensive animal protein sources.