Hello. My name is Neil Jaworski, and I'm a PhD student here in the Hans H. Stein Monogastric Nutrition Laboratory. I am excited to discuss some research we conducted, determining the effect of a 3-strain Bacillus-based direct fed microbial on growth performance and volatile fatty acid production in nursery pigs fed low or high fiber diets. The outline that I'll follow today is that I'll begin with a brief introduction to direct fed microbials; then I'll move into the materials and methods that we used for this experiment; then I'll move into the results and discussion, concerning the growth performance of pigs and also cecum and fecal concentrations of volatile fatty acids; and then I'll leave you with the conclusion and a brief take home message. Direct fed microbials, which I'll abbreviate as DFM for the remainder of the presentation, may be more commonly known as probiotics. But since 1989, the FDA has required feed manufacturers to use the term DFM. Now, DFMs are defined as a source of live, or viable, naturally occurring microorganisms. And for this experiment, we wanted to utilize a Bacillus-based DFM. And this is because Bacillus-based DFMs are spore forming. and these spores survive high temperatures which can occur during feed manufacturing, and also a low pH of the stomach. Then, in the more pH neutral environment of the small intestine, the Bacillus-based DFMS should begin to germinate and proliferate. And there, and throughout the large intestine, they produce a large quantity and variety of fiber degrading enzymes. And that is why we determined the efficacy of the DFM in low and high fiber diets. The objective, therefore, of the experiment was to determine the effects of a 3-strain Bacillus-based DFM added to low or high fiber diets on cecum and fecal volatile fatty acid concentrations, and also growth performance. We utilized 200 pigs with an initial body weight of 6.31 ± 0.73 kg randomly allotted to a 2x2 factorial arrangement, with two diet types, low or high fiber; and two levels of DFM, 0 or 60 g of DFM per ton of feed. And this DFM contained 2.4x10^12 colony forming units per kg. And there were two experimental phases: from day 0 to day 14, and day 14 to day 43. On day 43 at the end of the experiment, one pig per pen was euthanized. And we collected cecum and rectal contents and analyzed those for volatile fatty acids. This is the ingredient composition of the phase 1 diets. You can see for the low fiber diets, we had corn, soybean meal, 15% whey, 5% fish meal, and 4% blood plasma. Whereas for the high fiber diets, we replaced some corn and soybean meal with 7.5% DDGS and 10% wheat middlings, and we maintained 15% whey, 5% fish meal, and 4% blood plasma. Here is the calculated and analyzed diet composition. We observed that the net energy is greater in low fiber diets. And this is because these diets were not formulated to be isocaloric. Also, we did not formulate these diets to be isonitrogenous. And therefore, crude protein was 1% greater in the high fiber diets compared with the low fiber diets. However, we did formulate for equal quantities of standardized ileal digestible indispensable amino acids, which you can see here; the SID lysine is equal between the low and high fiber diets. Moving on to the analyzed concentrations of ADF, NDF, soluble dietary fiber and insoluble dietary fiber, we observed that the high fiber diets had greater quantities of all these fiber components. Moving on to the phase 2 diet ingredient composition: the low fiber diets, again, were corn and soybean meal based, with 10% whey and 4% fish meal, and no blood plasma was added in the phase 2 diets. And then, again, the high fiber diets replaced some corn and soybean meal with 15% DDGS and 10% wheat middlings. And again, we maintained 10% whey and 4% fish meal in the high fiber diet. Looking at the phase 2 diet analyzed and calculated composition, we again observe that the low fiber diet contained more net energy compared with the high fiber diet, and less crude protein. Again, SID lysine was equal amongst the low and high fiber diets as well as the other indispensable amino acids. And we observed that high fiber diets had greater concentrations of ADF, NDF, soluble, and insoluble dietary fiber. And it's interesting to note that the high fiber phase 2 diets have a greater amount of soluble dietary fiber compared with the phase 1 diets. For the statistical analysis, we used the Mixed procedure of SAS. And the model was a 2x2 factorial arrangement with the fixed effects of diet type, DFM, and the interaction of DFM and diet type. And the random effect was block and replicate. Now, we'll move into the results and discussion. First, I'll take a moment to set up the graph. Here, we're looking at body weight of the pigs at the different time points, which are on the x axis -- so day 0; day 14, which was the end of phase 1; and day 43, which was the end of phase 2. And on the y axis, we have body weight in kilograms. The orange bars represent the low fiber diets, and the green bars represent the high fiber diets. And the checkered bars represent the diets that included the direct fed microbial. On days 0 and 14, we observed no difference in body weight of pigs fed the experimental diets. But on day 43, nursery pigs fed high fiber diets had reduced body weight compared with low fiber pigs. So why did we observe this difference in pig body weight due to fiber level? Well, if we take a look at average daily feed intake, we observed that during days 0-14, or phase 1, high fiber fed pigs were unable to consume as much feed as their low fiber fed counterparts. And this may be attributed to increased gut fill due to the increased diet bulk in the high fiber diets, indicating that nursery pigs are unable to handle the bulk from days 0 to 14. But, from days 14 to 43, or phase 2, statistically, high fiber fed pigs were able to consume an equal amount of feed as their low fiber counterparts. But overall, from day 0 to day 43, nursery pigs fed high fiber diets had reduced average daily feed intake. Again, we need to keep in mind that high fiber diets had less net energy, and therefore pigs would have to consume more in order to maintain body weight, and this was not the case. Also, the addition of direct fed microbials to the low or high fiber diets did not influence average daily feed intake. Because high fiber fed pigs were unable to consume or increase their average daily feed intake above their low fiber fed counterparts, the high fiber fed pigs had reduced average daily gain during phase 2, from days 14 to 43, and overall from days 0 to 43, compared with their low fiber fed counterparts. And again, we observed no difference in average daily gain due to the addition of direct fed microbials to low or high fiber diets. We observed that the addition of DFM to diets increased gain:feed during phase 1 and overall from days 0 to 43. Also, gain:feed was improved by 26% in high fiber fed pigs compared with only a 15% improvement in gain:feed of low fiber fed pigs, indicating that the DFM is making more energy available to the pigs on high fiber diets compared with pigs fed low fiber diets during phase 1. Now, we have to remember that the diets were not formulated to be isocaloric. So presenting gain:feed on a g/g basis may not be appropriate and may be why we observed no fiber effect on gain:feed. But when we present gain:feed on a kg/Mcal net energy intake basis, which takes the differences in net energy into account, we again observe no effect of fiber on gain:feed, which indicates that the nursery pig fed a high fiber diet is still as efficient in utilizing the energy for gain as their low fiber counterparts. But they're just unable to consume enough feed to maintain a similar average daily gain. Also indicated on this graph is that the DFM improves the caloric efficiency of pigs fed low fiber and high fiber diets. Now, we're moving into the total short chain fatty acid concentration in cecal digesta on the left, and fecal contents on the right, presenting in μg/g on a dry matter basis. We observed no effect of fiber or DFM on total short chain fatty acid concentration in cecal digesta. But in fecal contents, we observe that the low fiber fed pigs had increased concentration of short chain fatty acid compared with their high fiber fed counterparts. Now, this goes against two of our hypotheses, in that we had hypothesized high fiber fed pigs would have greater concentrations of short chain fatty acids in both cecal and fecal contents, because there would be more fermentation occurring. And this was not the case in fecal contents; it was just the opposite. Low fiber fed pigs had increased short chain fatty acids. Also, we hypothesized that the addition of direct fed microbials to low or high fiber diets would increase fermentation, and therefore we would observe increased short chain fatty acid concentrations due to DFM. And again, this was not the case. And so we must conclude that perhaps the low fiber corn-soybean meal based diet is more fermentable compared with the high fiber diet and that the addition of the Bacillus-based direct fed microbial is not increasing fermentation and increasing short chain fatty acid production, and this is not the reason why gain:feed was increased due to DFM addition in both low and high fiber diets. However, if we correct our short chain fatty acids and present it on a g/day dry matter basis, taking into account the low digestibility of these high fiber diets, then we observe a trend that we expected. So on the left hand graph, we calculated the fecal excretion in g/day using the average daily feed intake, and then the apparent total tract digestibility of dry matter that we determined in a subsequent study using similar diets. And when we do that calculation, we observe that high fiber fed pigs had a greater amount of feces excreted compared with low fiber fed pigs. Again, this is due to the low apparent total tract digestibility of dry matter in high fiber based diets. Then, on the right hand graph, we have cecal and fecal short chain fatty acids presented in g/day, which take into account the fecal excretion or the low digestibility of dry matter, and therefore a greater amount of substrate moving through the hindgut of the pig. And therefore, we have increased short chain fatty acids in both the cecal digesta and feces contents of pigs fed high fiber diets compared with low fiber fed pigs. In conclusion, high fiber diets decreased overall average daily feed intake, which reduced average daily gain. And this is because the nursery pigs were unable to handle the diet bulk associated with high fiber diets. Also, we observed a decreased short chain fatty acid concentration in μg/g in the feces of pigs fed high fiber diets, which indicates that fermentation may be maximized in a low fiber corn-soybean meal compared with a high fiber diet. However, if we take into account the low digestibility and increased substrate availability in the hindgut of high fiber fed pigs, we can observe increased overall short chain fatty acid in g/day. And the 3-strain Bacillus-based direct fed microbial added to both low and high fiber diets improved overall gain:feed. However, the mode of action is unclear, but we are certain that it is not due to increased fermentation and increased short chain fatty acid production. But another hypothesis that we have is that perhaps the DFM reduced inflammation in the GI tract, which would reduce immune system stimulation, thereby decreasing the pig's maintenance energy requirement, which would leave more energy available for production purposes. But more research is necessary to determine the exact mode of action of this 3-strain Bacillus-based DFM. The take home message is that using a 3-strain Bacillus-based DFM improved nursery pig gain:feed. But this was not due to increased VFA production. And the concentration of short chain fatty acids was not greater in pigs fed high fiber diets, indicating that for some reason, fermentation cannot be maintained at the same extent as low fiber diets. We would like to acknowledge DuPont and Danisco Animal Nutrition for funding this project. Thank you for watching this podcast, and please go to our website if you have any further questions.