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Performance and nitrogen balance of growing gilts fed low-protein, amino acid -supplemented diets

Jose Luis Figueroa-Velasco, University of Nebraska - Lincoln


Five experiments were conducted to investigate the effect of crude protein (CP) concentration and amino acid (AA) supplementation on growth performance and nitrogen (N) balance of growing gilts. In Experiment 1, a N balance trial, 12 gilts were fed diets with CP contents of 18 or 14% + AA, 16 or 12% + AA, 14 or 10% + AA in an incomplete block design. Low-CP diets were supplemented with lysine, tryptophan, threonine, and methionine at same total amount as their high CP diet counterpart. Experiments 2–5 were growth performance trials using 36 gilts for 35 d each. In Experiment 2, diets contained 16, 15, 14, 13, 12, or 11% CP. In Experiment 3, diets were: 16% CP, 12, 11, 11 + isoleucine, 11 + valine, and 11 + isoleucine + valine. In Experiment 4, diets were: 16% CP, 12, 11, 11 + histidine, 11 + histidine + valine + isoleucine, and 11 + histidine + valine. In Experiment 5, diets were: 16% CP, 12, 11, 11 + valine, 11 + valine + histidine, and 11 + valine + isoleucine. All AA were supplemented to equal total amounts in the control diet. In Experiment 1, reducing CP concentration linearly reduced N retention (P < 0.001). Gilts fed intact protein had higher N retention and apparent digestibility of N (P < 0.001). In growth performance experiments, gilts fed the 11% CP diet had lower growth performance than gilts fed other dietary CP concentration (P < 0.01). Dietary CP concentration affected plasma urea (P < 0.01), plasma concentrations of essential AA, and longissimus muscle area (P < 0.05). Isoleucine or histidine supplementation decreased growth performance (P < 0.01). Valine + isoleucine supplementation increased growth performance to similar levels as gilts fed 12 or 16% CP diets (P > 0.05). Nitrogen balance seemed more sensitive than growth to AA adequacy. These results indicate that valine and isoleucine are the fifth and sixth limiting AA in a corn-soybean meal, AA-supplemented diet for growing gilts. Growing gilts can be fed an 11% CP diet supplemented with lysine, tryptophan, threonine, methionine, valine, and isoleucine. ^

Subject Area

Agriculture, Food Science and Technology|Agriculture, Animal Culture and Nutrition

Recommended Citation

Figueroa-Velasco, Jose Luis, "Performance and nitrogen balance of growing gilts fed low-protein, amino acid -supplemented diets" (2000). ETD collection for University of Nebraska - Lincoln. AAI9976987.