Submitted to: Journal of Animal Science
Publication Type: Abstract Only
Publication Acceptance Date: 7/25/2004
Publication Date: 7/25/2004
Citation: Dean, D.W., Southern, L.L., Kerr, B.J., Bidner, T.D. 2004. The isoleucine requirment of 80- to 120-kilogram barrows. Journal of Animal Science. 82(1):296.
Technical Abstract: Three experiments were conducted to validate an Ile deficient diet and then to determine the Ile requirement of 80- to 120-kg barrows. Crossbred barrows (n = 60, 80, or 80 with initial BW of 93, 82, and 85 kg, respectively) were used in each experiment. In Exp. 1, five replications with four pigs per pen were fed diets containing either a corn-soybean meal diet (C-SBM) or a corn-based diet containing 5% blood cells (BC) with or without 0.26% supplemental Ile (C-BC+Ile or C-BC) in a 28-d growth assay. On d 14, pigs receiving the C-BC diet were taken off experiment due to a severe depression in feed intake. Growth performance was not different for pigs fed C-SBM or C-BC+Ile (P = 0.36) over the 28-d experiment. In Exp. 2, four replications with four pigs per pen were fed the C-BC diet containing 0.24, 0.26, 0.28, 0.30, or 0.32% true digestible (TD) Ile. The experiment lasted 7 d and was an attempt to estimate the Ile requirement using plasma urea nitrogen (PUN) as the response variable. Because of dramatic incremental increases in ADFI as TD Ile was increased, PUN could not be used to estimate the Ile requirement. In Exp. 3, five replications with four pigs per pen were fed the C-BC diet containing 0.28, 0.30, 0.32, 0.34, or 0.36% TD Ile. Three pigs per pen were slaughtered on d 33 or 61 for determination of carcass lean and fat measurements (117.8 kg average final BW). Daily gain, ADFI, and gain:feed were increased linearly (P = .007) as Ile was increased in the diet. There were no effects of TD Ile level on 10th rib fat depth or loin muscle area; however, kilograms of lean was increased linearly (P < .001) as TD Ile level increased. In summary, the Ile deficiency of a C-BC diet can be corrected by the addition of supplemental Ile, and the PUN method is not suitable when assessing Ile requirement due to dramatic changes in ADFI. The TD Ile requirement for 80- to 120-kg barrows for maximizing feed intake, growth, and kilograms of lean is not less than 0.36%.