Hi everyone, I'm Charmaine Espinosa, a PhD student under Dr. Hans H Stein. Today, I'll present some of the research we have conducted regarding copper hydroxychloride, which is also part of my dissertation. The requirement for copper by weanling pigs is around five to six milligrams per kilogram in the diet. And if this amount is included in diets, deficiency symptoms are not observed and we expect that animals are of normal health status. Copper may also be included at growth-promoting levels in diets for weanling and growing pigs. It is well established that copper included at the range of 75 to 250 milligrams per kilogram in diets for pigs usually improve average daily gain and gain to feed ratio. However, the exact mechanism of copper in exerting this positive effects has not yet been elucidated and is still unclear. One of the hypothesized mechanisms of copper in improving growth performance is that copper may have the ability to improve animal fat utilization and enzymatic activity. Copper is involved in metabolic reactions as a component of several metal enzymes which may stimulate enzyme activities involved in nutrient digestion. Therefore, addition of high concentrations of copper may increase lipase activities in the small intestine, which may result in increased absorption of fatty acids and improved growth performance. Dietary copper is also believed to have bacteriostatic and bactericidal properties because copper may reduce bacterial populations and activity in the intestine, which may affect growth and community structure of microorganisms in the cecum and in the colon. It is therefore possible that inclusion of copper in diets alters microbial activity and synthesis of endogenous microbial fat in the hindgut. However, to our knowledge the effects of copper on endogenous loss of fat have not been reported. Therefore, the objective of this work was to test the hypothesis that inclusion of 150 milligrams per kilogram of copper from copper hydroxychloride improves gain to feed ratio of pigs due to improved digestibility of fat. This research consists of two experiments, and the first one is a growth performance trial. In this experiment, 144 pigs were used with two pigs per pen and 12 replicate pens per treatment. These pigs were randomly allotted to six dietary treatments. The first diet is formulated based on corn, soybean meal and distillers dried grains with solubles or DDGS. Three additional diets were formulated by adding 2, 4, and 6% choice white grease to the basal corn-soybean meal-DDGS diet. Two additional diets were formulated by adding 150 milligrams per kilogram of copper from copper hydroxychloride. These diets were fed to pigs for 28 days. Moving on with the results, this figure shows the gain to feed ratio of pigs fed diets containing increasing levels of choice white grease and 150 milligrams per kilogram of copper from copper hydroxychloride without or with 2% choice white grease. So, the bars here are represented with increasing intensity of orange to red as inclusion of choice white grease in the diets increased. For the overall experiment, the gain to feed ratio of pigs linearly increased as the concentration of choice white grease increased in the diets. So, this linear improvement allowed us to conduct a linear regression analysis and a prediction equation was derived with 0.526 as the intercept and 0.022 as the slope. This indicates that gain to feed ratio of pigs increases by 0.022 for each percentage unit change of choice white grease inclusion in the diet. You can also observe here that supplementation of copper from copper hydroxychloride improved gain to feed ratio of pigs from 0.526 to 0.609, and based from the prediction equation, it was calculated that the improvement in gain to feed ratio upon copper supplementation was similar to the improvement obtained by adding 3.8% choice white grease to the diet. Likewise, inclusion of 2% choice white grease and supplementation of copper hydroxychloride to the diet improved the gain to feed ratio of pigs from 0.526 to 0.632, which resulted in a 4.8% choice white grease equivalency: 2% coming from choice white grease and 2.8% coming from copper hydroxychloride. Therefore, what we can conclude in this experiment is that inclusion of choice white grease and supplementation of copper hydroxychloride to diets improved gain to feed ratio of pigs, and the improvement in gain to feed ratio upon copper supplementation was similar to the improvement obtained by adding 2.8 to 3.8% choice white grease to the diets. So, how does copper exert these positive effects in the feed efficiency of pigs? Now we want to shed some light into these questions. Therefore, we conducted an experiment to test the hypothesis that copper hydroxychloride reduces endogenous loss of fat and also improves the digestibility of fat in these pigs. In this experiment, 64 pigs were used and were allotted to eight dietary treatments for a total of eight replicate pigs per diet. A basal diet based on corn, soybean meal, and corn bran at 27% was formulated. Three additional diets were then formulated by adding 15, 30, and 45% DDGS to the basal diet. Now, I want to emphasize here that as we increase the inclusion of DDGS, the dietary concentration of fat also increased. And you can also observe here that the concentration of corn bran was reduced as DDGS was increased to maintain a constant concentration of dietary fiber among these diets. Lastly, four additional diets were formulated by adding 150 milligrams per kilogram of copper from copper hydroxychloride to the first four diets. Moving on with the results, this graph shows the apparent total tract digestibility of acid hydrolyzed ether extract, or fat, in diets with increasing concentration of distillers dried grains with solubles without or with 150 milligrams per kilogram of copper from copper hydroxychloride. So the blue bars here represent the digestibility of fat in diets without added copper and the orange bars here represent diets with 150 milligrams per kilogram of copper. And here we can observe that the digestibility of fat linearly increased as the concentration of DDGS increased in diets, which is likely a result of the increased concentration of dietary fat. What's also interesting here is that supplementation of copper hydroxychloride to the control diet and to the diet containing 15% DDGS also improved the ATTD of fat. Likewise, the ATTD of fat in the diet containing 30% DDGS with supplemental copper tended to be greater compared with the diet without supplemental copper. However, if you take a look into this graph in here, you can observe the apparent total tract digestibility of gross energy. We can observe that supplementation of copper hydroxychloride did not improve the digestibility of gross energy, and this is in contrast to what we have observed in the effect of copper in improving the digestibility of fat. Well, why is that? Well, this was due to the effect of copper in reducing the endogenous loss of fat from 11.2 to 7.1 grams per kilogram of dry matter intake. Dietary copper reduces a number of bacterial species in the small intestine and in the cecum and colon of pigs, and this may have reduced fermentation of fiber in the hindgut with a subsequent reduction in endogenous loss of fat, since majority of fecal fat is of microbial origin. We also estimated a true total tract digestibility of fat in these diets without or with supplemental copper. However, we did not see any differences among these treatments. Therefore, the improvement in the apparent total tract digestibility of fat upon copper supplementation is only due to the effect of copper in reducing the endogenous loss of fat. So based on these results, we can conclude that supplementation of 150 milligrams per kilogram of copper as copper hydroxychloride to diets increased the gain to feed ratio of pigs. Copper hydroxychloride supplementation also resulted in an improvement in fat digestibility by reducing the endogenous loss of fat. However, the observed improvement in growth performance was not a result of improved energy or fat digestibility because the true total tract digestibility of fat was not improved by adding 150 milligrams per kilogram of copper from copper hydroxychloride. So, if it's not due to digestibility, copper may have some effects in post-absorptive metabolism of lipids wherein copper may influence at the mRNA expression of proteins involved in fatty acid uptake and utilisation. And this is actually what we are trying to validate right now. With that, we would like to take this opportunity to acknowledge Micronutrients and AgriSpecialist for their financial support. Thank you for listening, and if you would like to learn more about other topics in nutrition, you can visit our website at nutrition.ansci.illinois.edu.