| Nine feed ingredients and 12 diets were used in an attempt to select the most suitable regression equations for predicting the nitrogen digestibility (ND) digestible energy (DE) and metabolizable energy (ME) for swine from chemical analyses or in vitro enzymatic digestion. Feed ingredients included were corn, sorghum grain and wheat, alfalfa meal, wheat bran and rice bran, soybean meal, meat and bone meal and sunflower meal. The relationship between chemical analyses (5-step) and in vivo ND, DE and ME of feeds measured with 72 growing pigs were computed with multiple regression equations. The in vitro enzymatic digestion procedure involved digestion of one gm of each feed with 20 ml of .20% pepsin for 2 hr followed with 80 mg pancreatin and 40 mg amylase for 6 hr in a 37 C water bath. The relationships between in vitro ND and dry matter digestibility (DMD) and in vivo results were computed with linear regression analyses.;A high correlation was found between the in vitro and in vivo results for ND and DMD. The relationships between in vivo (y) and in vitro (x) digestibilities for diets and feed ingredients with .5 mm particle size were shown as the following equations. . . . (Author's abstract exceeds stipulated maximum length. Discontinued here with permission of author.) UMI.;From conventional digestion and balance trials, high correlations were found between DMD, DE and ME. Fiber was the major factor depressing DMD, ND, DE and ME in both diets and feed ingredients. The DE and ME could be predicted from only CF and Ash in feed ingredients by the following equations: DE,kcal/g DM = 4.360 - .0652 CF - .0489 Ash, (r = .93, P < .01); ME,kcal/g DM = 4.277 - .0676 CF - .0516 Ash, (r = .95, P < .001). Using the highest correlation coefficients and the lowest residual standard deviations, the following equations gave the best prediction for ND, DE and ME of the diets and feed ingredients from chemical analyses. Diets: ND,% = 83.55 + .414 CP - 1.007 EE - 1.243 CF, (r = .92, P < .01); DE,kcal/g DM = GE x (95.21 - 1.249 EE - 1.723 CF), (r = .91, P < .001); ME,kcal/g DM = GE x (93.22 - 1.171 EE - 1.760 CF), (r = .90, P < .001). Feed ingredients: ND,% = 73.68 + .617 CP - .701 CF - .886 Ash, (r = .91, P < .05); DE,kcal/g DM = 5.944 - .080 CF - .106 Ash - .019 NFE, (r = .97, P < .001); ME,kcal/g DM = 4.277 - .0676 CF - .0516 Ash, (r = .95, P < .001). |
