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Eric van Heugten, Brooke Anderson, Jon Holt, and R. Dean Boyd, North Carolina State University Animal Nutrition Research, LLC | June 10, 2021
Soybean meal is traditionally considered an excellent source of protein for pigs because it has a balanced amino acid composition and a competitive cost compared to other protein sources. Over the years, due to the availability of crystalline amino acids, the increased use of soluble distillers grains (DDGS), and the decline in the price of tryptophan, the content of soybean meal in pig diets has declined; the latter has led to a sharp decline in dietary soybean meal. For example, 2000 (without DDGS and 3 lb/ton lysine), 2008 (12 lb/ton lysine because tryptophan became affordable), 2010 (DDGS accounted for 20%), 2017 (Actively using 35% of DDGS will contain approximately 464, 346, 172, and 52 pounds per ton of soybean meal. Therefore, the addition of soybean meal to pig diets depends largely on pricing, and apart from the source of amino acids In addition to the contribution, no consideration is given to any potential value of soybean meal. However, soybean meal contains a large number of health-promoting compounds, such as isoflavones, saponins and phenolic antioxidants, which have been shown to regulate immune responses and improve pigs exposed to the challenge of viral diseases Growth performance (see review by Smith and Dilger, 2018). J. Anim. Sci. 96:1288-1304). Due to the addition of DDGS and high levels of crystalline amino acids, the content of soybean meal in the diet has been reduced to a very low level, especially in the late fattening diet, which largely eliminates the growth and potential health promotion provided by soybean meal. benefit.
Because crystalline tryptophan has reliable cost-effectiveness, and as the availability of valine and even isoleucine increases, it is more affordable, so there is a greater ability to reduce the content of dietary soybean meal even lower. A study conducted more than 20 years ago showed that as the content of soybean meal dropped from 375 pounds/ton to close to zero (in 110 pounds of pigs), pigs became fatter and less efficient despite the restoration of the original diet. Indispensable and optional amino acids. Potassium levels and dietary electrolyte balance are also maintained at or above the safe minimum (Johnson, Usry and Boyd, 1999. J. Anim. Sci. 77 (Suppl. 1): 69). We now believe that this is not a limitation of crude protein, but is related to the growth and health-promoting ingredients that are not common in substitutes in soybean meal. In addition, there may be soybean meal levels below this level that will affect growth and feed conversion; this may vary depending on the growth stage and high or low health status (respiration).
We conducted a study funded by the Soybean Inspection Fund to determine the effect of replacing soybean meal with DDGS and high-level crystalline amino acids on the performance of growing pigs. There are 512 pigs in total, with an average weight of 84.9 ± 0.3 pounds. Blocked by BW and gender and put into 64 pens (4 gilts and 4 push pigs per pen). The fence is assigned to 8 diet treatments (8 blocks for each treatment), arranged in a 2 × 4 factorial. Factors include DDGS supplements (0 or 25%) and crystalline amino acid supplements (L-lysine-HCl added at 0, 4, 8 or 12 pounds per ton, DL-methionine, L-threonine, L-color Amino acid, supplemented with L-valine and L-isoleucine to maintain an appropriate standardized ileal digestible (SID) amino acid ratio. Diet processing is divided into two stages, each containing 1.00% (stage 1, 21 days) ) And 0.90% (phase 2, 18 days) of SID lysine, and balance the ideal protein and net energy. SID methionine plus cystine, threonine, tryptophan, valine and The ratio of isoleucine to SID lysine is set to the minimum of 0.58, 0.63, 0.19, 0.67, and 0.56 for the phase 1 diet, while 0.59, 0.69, 0.64, and 0.64 are used for the phase 2 diet. For no DDGS For the control diet, the dietary SBM content decreased as the content of crystalline amino acids decreased from 32.06% to 13.14% (stage 1) and 28.25% to 9.40% (stage 2). With the crystalline amino acids in the DDGS diet As the content increases, the content of SBM decreases from 27.85% to 8.89% (stage 1) and 24.05% to 5.10% (stage 2).
Replacing part of soybean meal with DDGS (P = 0.024 and 0.032, respectively) and crystalline amino acids (P <0.001) can reduce average daily gain and final body weight (Figure 1). At the end of the study, the pigs fed the DDGS diet lost 2.46 pounds, and the replacement of soybean meal with 12 pounds/ton of lysine·HCl (plus other crystalline amino acids) resulted in a final weight loss of 5.71 pounds. The response to supplementation of crystalline amino acids depends on the addition of DDGS; when the diet does not contain DDGS, the addition of crystalline amino acids will linearly reduce the growth rate and final body weight, while the reaction of adding DDGS to the diet is secondary. Similarly, after adding crystalline amino acids to the control diet, the feed intake decreased linearly, but when added to the diet containing DDGS, the feed intake showed a quadratic response (interaction, P = 0.004; graph) 2). Feed: The pigs fed the DDGS diet were 3.2% higher than the control fed pigs and consumed 0.08 lbs. More feed per pound of weight gain. Feeding diets with supplemental crystalline amino acids (12 lbs/ton lysine·HCl) resulted in a feed: a 4.2% increase in weight gain or 0.10 lbs. More feed per pound of weight gain.
Substituting DDGS for soybean meal will reduce the growth rate and increase the feed: weight gain, while the addition of crystalline amino acids has a negative impact on the growth and feed efficiency of the soybean meal control diet, but will not cause a further reduction in the DDGS-containing diet. The diet is carefully formulated to meet the requirements of standardized ileal digestible lysine, methionine plus cystine, threonine, tryptophan, valine and isoleucine, but the growth performance is due to the high content of crystalline amino acids And be affected. Therefore, increasing the amount of soybean meal in the diet is positively correlated with increasing total weight gain and feed efficiency (Figure 3). Compared with the diet containing DDGS (red circle), the total weight gain response of adding soybean meal to the control diet (blue circle) is more obvious. On the other hand, feed efficiency increases linearly with the addition of soybean meal, and has nothing to do with the addition of DDGS. It should be noted that the pigs in this study are very healthy, and the impact of soybean meal is more pronounced under the challenge of respiratory health. These effects may be more important, especially in the summer, when the average daily gain is a premium for reaching market weight.
Source: Eric van Heugten, Brooke Anderson, Jon Holt, and R. Dean Boyd, North Carolina State University Animal Nutrition Research Co., Ltd. They are fully responsible for the information provided and fully own the information. Informa Business Media and all its subsidiaries are not responsible for any content contained in this information asset.
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