Slide 1 Good afternoon. This is Hans H. Stein. I am an associate professor in the Department of Animal Sciences at the University of Illinois. I would like to talk to you today about the impact of sulfur on the palatability and growth performance of pigs fed DDGS-containing diets. Slide 2 The outline I would like to follow includes the following. First, I will give a little bit of a background for our experiments. Then I will talk about the four experiments we conducted. Then I will show the results from these four experiments, and finally I will talk a little bit about the implications from this research. Slide 3 Corn grain contains approximately 0.1% sulfur. Because the starch in corn is fermented during ethanol production, DDGS is expected to contain about 0.3% sulfur, because most of the nutrients in DDGS is three times greater than the concentration is in corn. However, the actual concentration of sulfur in DDGS is not always 0.3%. Sometimes, we see values all the way up to 0.9% or even more than that. So, there is a lot more sulfur in DDGS, in some cases at least, than what is coming directly from the corn grain. And the reason for that is that sulfuric acid is sometimes used in the ethanol plants to stabilize the pH during fermentation. And that's why the sulfur concentration sometimes is increased. Now, we know that sulfur can be a problem in cattle nutrition, and high levels of sulfur can contribute to diseases in cattle. However, there is very little information about the effects of sulfur in swine nutrition. Slide 4 It has been recognized and shown many times that between 20 and 30% DDGS can be included in diets fed to swine without reducing growth performance, but sometimes we do see a reduction in feed intake when DDGS is included in the diets. And it has been concluded that pigs, if they have a choice, they will prefer to eat diets that contain no DDGS rather than diets that contain DDGS. And we therefore came up with the hypothesis that maybe the reduced feed intake that is sometimes observed in diets containing DDGS could be related to the concentration of sulfur in DDGS. Slide 5 So the objective of this research was to measure the effects of the inclusion of DDGS and elevated sulfur concentration levels on diet palatability and pig growth performance. Slide 6 We conducted four experiments. The first experiment was conducted with the objective to measure the effect of sulfur on feed palatability using nursery pigs. And in the second experiment, we used the same diets to measure the effects of sulfur in DDGS on growth performance in nursery pigs. The third and fourth experiments were conducted with growing pigs. And in the third experiment, we measured the effects of DDGS on feed palability or feed preference in growing pigs, and in the fourth experiment we used those diets from Experiment 3 and measured the growth performance of growing-finishing pigs fed diets containing different levels of sulfur in DDGS. Slide 7 The diets we used for the two nursery pig experiments are shown here. We had three diets. The first diet was a control diet, simply a corn/soybean meal diet containing 23% soybean meal, 73% corn, and then we had some other ingredients -- vitamins, minerals, and amino acids. The total sulfur concentration in this diet was 0.22%. The we formulated a corn/soybean meal/DDGS diet and we had 20% DDGS in this diet. The DDGS we used in this diet was selected to have a relatively low concentration of sulfur, so the DDGS here contained 0.3% sulfur, and that is in the low end of what we usually see in DDGS. And you'll see the total concentration of sulfur in this diet was about the same as it was in the control diet at 0.22%. However, we then formulated a third diet, and the third diet was similar to the second diet with the exception that we added calcium sulfate to this diet to increase the concentration of sulfur from 0.22% up to 0.34%. And the reason we added this level of sulfur was that 0.34% would be the level of sulfur one would get in the diet containing DDGS if the DDGS had the highest level of sulfur that we have observed, which is around 0.9%. Slide 8 The diets for the growing pigs are shown on this slide. As for the nursery pigs, we used three diets in this experiment. We had a control diet containing corn and soybean meal mainly, and this diet contained 0.206% sulfur. We again used a source of DDGS with a low level of sulfur to formulate our second diet, and this diet contained 61% corn, 6% soybean meal, and 30% DDGS, and the total concentration of sulfur in this diet was 0.198%. Then we had the third diet, which was a high-sulfur diet. And this diet was formulated by adding 1.10% calcium sulfate to the DDGS-containing diet. So the total concentration of sulfur in this diet was 0.375%. And as in the nursery pig diets, this level of sulfur was calculated to be similar to the level of sulfur one would obtain if we had used a DDGS source with 0.9% sulfur. Slide 9 The results of these experiments are shown next. Slide 10 The feed preference of the nursery pigs is shown in this slide. We have here, on the Y-axis, the feed preference on a percentage basis, and on the X-axis, we have the different diets that were fed. The way we conducted this experiment was that we had a total of 30 pens. In 10 of the pens, we had two feeders. These two feeders contained the control diet and the DDGS diet, so there was a choice for the pigs to eat either the control diet or the DDGS diet. The feeders were switched every day, so that the pigs would not know beforehand which diet was in which feeder. So the disappearance of feed from each feeder represents truly the preference of the pigs, and we measured the disappearance every day for eight days. The second group compared the control diet and the DDGS+sulfur diet. Again, we had ten pens, and we had two feeders in each pen, and pigs were fed every day, feeders were switched every day, and feed disappearance was monitored every day. And the third group had two feeders and in these feeders we had either the DDGS-containing diet or the DDGS+sulfur diet. As is apparent here, when the control diet and the DDGS diet were fed, we saw a much greater preference for the control diet than for the DDGS diet; about 65% of all the feed that was consumed in those pens was the control diet, and only 35% of the feed that was consumed was the DDGS diet. And looking at the second group, we saw exactly the same picture; about 65% of the feed consumed was the control diet, and a little over 30% of the feed consumed was the DDGS+sulfur diet. So again, clearly the pigs preferred to eat diets containing no DDGS if they had a choice. However, the third group showed that if the pigs have a choice between a DDGS diet and a DDGS diet with high sulfur, there is very little difference in the consumption of feed, and they pretty much eat 50% of each diet. There is no significant difference between these two diets. So what this indicates is that pigs prefer to eat diets containing no DDGS, but there does not seem to be any preference for eating diets with low sulfur versus diets with high sulfur. So those were the results from the first experiments. Slide 11 We repeated this experiment with growing pigs. And the setup was the same as for the previous slide: we had three groups of pigs, and we had two feeders in each pen, and we had ten pen replicates per group. And again we saw here that if the pigs were given a choice between the control diet and the DDGS diet, they preferred to eat the control diet, so about 70% of the feed consumed was the control diet, whereas only 30% was the DDGS diet. And we saw exactly the same picture if we used the DDGS diet with high sulfur concentration; about 30% of the DDGS+sulfur diet was consumed and almost 70% of the control diet was consumed. However, as was the case with the nursery pigs, we also saw for the growing pigs that if the pigs had the choice between DDGS and DDGS+sulfur diets, they seemed to eat about the same amount of each diet. So about 50% of the DDGS diet was consumed, and about 50% of the DDGS+sulfur diet was consumed. So the result of this experiment with growing pigs was exactly the same as what we saw with the nursery pigs, where pigs prefer to eat the control diet if they have a choice, but they don't seem to really care whether there is a high or a low level of sulfur in the DDGS. Slide 12 Looking at growth performance for the nursery pigs. The pigs were about 10 kg when we started, so they were approximately two weeks post-weaning, and we fed them these diets for three weeks. So they were a little over 20 kg when we completed the study. And we can see here that the average daily gain was significantly greater when pigs were fed the control diet compared with pigs fed the DDGS diet or pigs fed the DDGS+sulfur diet. However, there was no difference between the two DDGS-containing groups. They had similar average daily gain. There were no significant differences in feed intake among the three groups; however, the gain:feed ratio was greater for pigs fed the control diet compared with pigs fed the two DDGS-containing diets. So that indicates that pigs utilize the feed a little bit better if they are fed the control diet compared with the DDGS-containing diets. Slide 13 The growth performance for the growing-finishing pigs was kind of similar to what we saw for the nursery pigs, where the pigs fed the control diet had a greater average daily gain compared with pigs fed the DDGS and the DDGS+sulfur diets; however, there was no difference between the two DDGS-containing diets. In this case, feed intake was also greater for pigs fed the control diet compared with pigs fed the two DDGS-containing diets, and the gain:feed ratio was greater for pigs fed the control diet than pigs fed the DDGS and the DDGS+sulfur diets. So the results of the growing-finishing experiment was very similar to the results from the nursery experiment. Slide 14 If we look at the conclusions from these experiments, we saw no effect of the sulfur on feed preference for nursery pigs and we saw no effect of sulfur on feed preference for the growing-finishing pigs. It appears that pigs prefer to eat corn/soybean meal diets compared with diets containing DDGS, but if they have to eat DDGS-containing diets, they don't seem to care whether there is a high or a low concentration of sulfur in that DDGS. Slide 15 On growth performance, we saw no effect of sulfur on feed intake, which is also what we expected after seeing the lack of an effect of sulfur on feed preferences. We saw no effect of sulfur on growth performance. However, in this experiment, pigs fed diets containing no DDGS performed better than pigs fed diets containing DDGS. And that was somewhat surprising because in previous experiments, we have shown that there is no difference in growth performance between pigs fed control diets and DDGS-containing diets. One reason for the reduced growth performance that we observed in these experiments may be that the DDGS we used in these experiments is of a poorer quality than what we have used in previous experiments. Slide 16 A few implications from this research ... Slide 17 The implication is that the concentration of sulfur in DDGS does not appear to affect feed palatability or feed preference of the diets. The concentration of sulfur in DDGS also does not affect pig growth performance, because pigs fed diets with low sulfur and high sulfur had exactly the same performance. However, questions about why pigs fed DDGS-containing diets sometimes perform less effeciently than pigs fed corn/soybean meal diets remain unanswered and more research in this area is required. Slide 18 With that, I want to thank you for your attention. If you have an interest in more information, please visit our website. You will see the web address on the screen.