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Continued genetic improvement necessitates the verification of nutrient requirements for newly developed pig genotypes. Amino acid needs are known to vary with pig genotype and using the correct estimates has positive economic as well as environmental implications. One of these amino acids is dietary lysine, mostly used for body protein synthesis, whose amount in the diet is directly related to the growth of piglets. The objective of this research was to determine the standardized ileal digestible (SID) lysine (Lys) requirement of 7- to 15-kg weanling pigs fed a corn-soybean meal-based diet. For that aim, a total of 144 piglets with an initial BW of 6.51 ± 0.56 kg (mean ± SD) were assigned to one of six diets using a randomized complete block design based on BW to give eight replicate pens with three pigs per pen. The six diets contained 1.00, 1.16, 1.32, 1.48, 1.64, and 1.80% SID Lys, achieved by adding crystalline L-Lys-HCl at the expense of corn starch. Other indispensable amino acids were provided to meet the requirements. Piglets had free access to diets and water for 21 days. Individual BW of pigs and feed disappearance were recorded weekly and blood samples were collected on day 1, 14, and 21.
Average daily gain (ADG) and average daily feed intake were not affected by dietary SID Lys content during the first 7 days. However, the addition of dietary SID Lys quadratically increased gain:feed (G:F) during the first 7 days of the experiment. A quadratic increase was found in both ADG and G:F when SID Lys content increased in the diets from day 14 to 21. During the overall experimental period, increasing dietary Lys content quadratically increased ADG and G:F, whereas plasma urea nitrogen quadratically decreased as SID Lys content increased. The SID Lys requirements were estimated for linear and quadratic broken-line models.
In conclusion, the SID Lys requirement for optimal growth performance of 7- to 15-kg weanling pigs fed corn-soybean meal-based diets based on linear and quadratic broken-line models were 1.27% and 1.30% for ADG and 1.27% and 1.43% for G:F, respectively, thus giving an overall average value of 1.32%.
Lee J, González-Vega JC, Htoo JK, Nyachoti CM. Evaluating the standardized ileal digestible lysine requirement of 7-to 15-kg weanling pigs fed corn-soybean meal-based diets. Animal. 2021; 15(2): 100127. https://doi.org/10.1016/j.animal.2020.100127