Hello everyone. My name is Maryane Oliviera, I’m a postdoc research associate in Dr. Stein’s laboratory at the University of Illinois. Today, the title of this podcast is “Crystalline amino acids in diets do not influence calculated values for amino acid digestibility in feed ingredients fed to pigs.” Values for standardized ileal digestibility of crude protein and amino acids in feed ingredients have been most commonly used in practical diet formulation. Therefore, ileal digestibility trials usually use diets that contain the test ingredient as the only source of crude protein and amino acids. And as a consequence of that, the amino acids supplied from experimental diets do not always meet the requirement for SID amino acids and therefore, pig growth is often limited in these experiments. Therefore, crystalline amino acids mixture is commonly included in experimental diets during the adaptation (which means the first five days) when conducting ileal digestibility trials to prevent amino acid deficiency in pigs. However, we hypothesize that if indeed crystalline amino acids are 100% digestible, it should be possible to include crystalline amino acids in experimental diets during the collection phase without influencing apparent ileal digestibility and standardized ileal digestibility for amino acids in feed ingredients. Based on that, we conducted this experiment to test the hypothesis that crystalline amino acids in diets will not influence apparent ileal digestibility or SID of amino acids in feed ingredients. Moving on to materials and methods…this experiment used seven pigs with an average of 78 kg body weight. The pigs had a T-cannula in the distal ileum. There was a total of seven experimental treatments and also seven periods. In this experiment, we formulated two different diets. The first diet was based on corn and corn starch that was not meeting the amino acid requirements for growing pigs. Each period consisted of seven days. The adaptation period was from day 1 to day 5 was the adaptation period and the collection period was day 6 and day 7. Based on that, Treatment 1 was a corn diet fed for all seven days. Treatment 2 was a corn and crystalline amino acid diet fed for adaptation period (meaning the first five days) and corn diet fed in the collection period. Treatment 3 was corn plus crystalline amino acids fed for all seven days. In these diets, we included those crystalline amino acids to meet the requirements. The second diet was based on soybean meal and corn starch, which meets the amino acid requirements for growing pigs. The same ways that was in corn diets, here, we had Treatment 4 with soybean meal diets fed for all seven days. Treatment 5 was soybean meal plus crystalline amino acid diets fed for adaptation period, and soybean meal diets fed for collection period. Treatment 6 was soybean meal plus crystalline amino acid diets fed for all seven days. the same amount of crystalline amino acids as previous diets was included with the exception that in this diet, the SID of amino acids in the diets were above the requirements of amino acids for growing pigs. Additionally, there was a nitrogen free diet to determine the endogenous losses of amino acids. For this experiment, the SID of amino acids in the diets was calculated in two different ways. Here we have the first calculation, that was a traditional calculation for SID, in which the SID were calculated by correcting AID values for basal endogenous losses divided by the total amino acids in the diets. Moving on to the results: this graph I’m going to present the results from the first calculation. Here, we have the SID of amino acids in corn diets with crystalline amino acids. The blue bar was no supplementation of amino acids in the diets. The red bar was amino acid supplementation for adaptation period, meaning five days. And the green bar is amino acid supplementation for all seven days. If you take a look at these data, the blue bar and red bar were not different for SID of amino acids, meaning no carry-over effect of crystalline amino acids from adaptation period to the collection period was observed. However, the green bar was greater than the blue and red bars. And the reason for these results may be that crystalline amino acids were 100% digestible and corn has relatively low SID of amino acids, thus crystalline amino acids in corn provided a larger proportion to total amino acids in corn. In contrast, if you take a look in this graph that show SID of amino acids in soybean meal diets with crystalline amino acids, in soybean meal diets, the SID of amino acids was not affected by amino acid supplementation either for the adaptation or collection period. The reason for that is because of the greater concentration of amino acids in soybean meal and therefore, the contribution of crystalline amino acids to the SID of amino acids in soybean meal is less if you compare with corn diets. Moving on to the second calculation, the SID of amino acids in diets was calculated by correcting the AID values for basal endogenous losses. However, for this calculation, we used just amino acids concentration in ingredients, disregarding the crystalline amino acids from the calculation. This graph shows the SID of amino acids based on amino acids in corn. The gray bar is no supplementation of amino acids. The orange bar is amino acid supplementation for five days and the green bar is amino acid supplementation for seven days. As we can see, there was no influence of the crystalline amino acids on values for SID of amino acids in corn. The same was true for SID of amino acids in soybean meal. This graph shows values for SID of amino acids in soybean meal were not affected by crystalline amino acids. The observation that results were similar for the two ingredients indicates 100% absorption of crystalline amino acids regardless of amino acid concentration in the diet, indicating that it is not a concern if amino acids are above the requirement in SID studies and that the capacity of amino acid absorption is not easily saturated. Therefore, these observations clearly demonstrate that crystalline amino acids are completely absorbed before the distal ileum. Moving on to the conclusions: The crystalline amino acids have no influence on amino acids in digesta collected at the distal ileum. Crystalline amino acids may be added to diets used to determine the SID of amino acids. Moreover, crystalline amino acids can be disregarded in calculation of AID or SID of amino acids in feed ingredients. The implication of that is: Diets that do not meet the requirements for amino acids may be supplemented with crystalline amino acids. Moreover, amino acid deficiency may be avoided and improve pig growth. With that, I would like to say thank you for listening. If you want to know more about our research, you can visit our website at nutrition.ansci.illinois.edu.