Submitted to: Journal of Animal Science
Publication Type: Abstract Only
Publication Acceptance Date: 3/19/2002
Publication Date: 3/19/2002
Citation: Kerr, B.J., Parr, T.M., Borg, B.S., Campbell, J.M., Bryant, K.L., Kidd, M.T. 2002. Development of an isoleucine deficient diet in growing and finishing pigs. Journal of Animal Science. 80(2):72. Interpretive Summary: There are only limited empirical estimates of the isoleucine requirement for growing-finishing pigs as estimated in the National Research Council Subcommittee on Swine Nutrition, 1998. As environmental issues with nitrogen losses from swine operations becomes more pressing and as the availability of crystalline amino acids becomes more economically viable, understanding amino acid limitations in low crude protein diets and their desired concentration in feeding programs for optimal production and minimal nitrogen excretion, is paramount. Results from two experiments show that utilization of red blood cells in swine diets clearly creates an isoleucine deficient diet. In addition, the data also shows that supplementation of crystalline isoleucine alleviates these depressions in growth, feed intake and feed efficiency to a level similar to pigs fed standard diets. This data will be utilized in future studies to estimate exact isoleucine requirements and concentrations relative to dietary lysine in growing-finishing pigs in an effort to fine tune requirement estimates of the National Research Council Subcommittee on Swine Nutrition, 1998. Research results described in this report provides nutritionists at universities, feed companies, and swine production units vital data on empirical research methodology on how to clearly define the isoleucine needs of growing-finishing swine to properly formulate their diets to optimize growth performance and ultimately to minimize nitrogen excretion.
Technical Abstract: Two, trials were designed to develop an isoleucine (Ile) deficient diet in growing (23-45 kg) and finishing (77-95 kg) pigs. In trial 1, 8 reps of 4 pigs/pen were fed a diet containing 4.2% red blood cells (RBC) with or without Ile, a diet containing 8.4% RBC with or without Ile, a low CP+AA control, or a high CP control. Diets were formulated to contain .90% digestible (d) lysine (dLys) with the unsupplemented 4.2% and 8.4% RBC diets formulated to a dIle:dLys ratio of .50 and .23, respectively. All other diets were formulated to a dIle:dLys ratio of .63. Daily gain (ADG), daily feed (ADFI) and gain:feed ratio (G:F) did not differ between pigs fed the high or low CP+AA diets (P>.05). Utilization of 4.2% RBC had no effect on ADG or ADFI (P>.10), but reduced G:F (P<.06) which was alleviated by Ile supplementation. Utilization of 8.4% RBC reduced pig performance (P<.01) which was improved with supplemental Ile (P<.01), but remained lower than pigs fed the low CP+AA diet (P<.10). In trial 2, 6 reps of 4 pigs/pen were fed a diet containing 2.9% RBC with or without Ile, a diet containing 5.8% RBC with or without Ile, a low CP+AA control, or a high CP control. Diets were formulated to contain .67% dLys with the unsupplemented 2.9% and 5.8% RBC diets formulated to a dIle:dLys ratio of .55 and .31, respectively. All other diets were formulated to a dIle:dLys ratio of .63. Performance did not differ between pigs fed the high CP, low CP+AA, or either 2.9% RBC diet (P>.10). Feeding 5.8% RBC reduced pig performance (P<.01), which was improved with Ile supplementation (P<.01) to a level not different from pigs fed either control (P>.10). Utilization of RBC offers a unique opportunity to evaluate Ile nutrition of growing and finishing swine.