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Title:Reducing crude protein levels in diets fed to young pigs to optimize growth performance and intestinal health
Author(s):Limbach, Joseph Raymond
Advisor(s):Stein, Hans H
Contributor(s):Ellis, Michael; Cattai de Godoy, Maria
Department / Program:Animal Sciences
Discipline:Animal Sciences
Degree Granting Institution:University of Illinois at Urbana-Champaign
Subject(s):crude protein
growth performance
blood characteristics
intestinal morphology
gene expression
Abstract:Two experiments were conducted to evaluate the effects of reducing the dietary crude protein (CP) concentration in diets fed to weanling pigs on growth performance, post-weaning diarrhea (PWD), blood characteristics, gut morphology, and products of protein fermentation. Both experiments used the same formulation of 3 corn-soybean diets to generate 3 experimental treatments: 3 diets contained 22% and 19% CP that provided amino acids (AA) at the requirement, and another diet contained 16% CP that did not provide AA to meet the requirement. A two-phase feeding program was used in both experiments. In the first experiment, thirty-six weaned pigs (7.87 ± 0.42 kg) were randomly allotted to the 3 dietary treatments with 12 replicate pigs per treatment to test the hypothesis that a reduction in dietary CP may improve blood characteristics associated with protein utilization, and improve serum vitamin levels, with a minimal negative effect on growth performance. Pigs were placed in individual metabolism crates, which acted as an additional stressor post-weaning. Results demonstrated that pig growth performance during the initial two weeks post-weaning was not affected (P > 0.10) by the reduction of dietary CP, however, overall body weight (BW), average daily gain (ADG), and the gain to feed ratio (G:F) were linearly (P < 0.05) decreased for the 28-d experiment. Blood urea nitrogen (BUN) concentration was the greatest (P < 0.05) on d 14, but the reduction of CP in the diet decreased (P < 0.05) BUN concentration. Both albumin and vitamin A in blood serum were the lowest (P < 0.05) on d 14. Serum vitamin E, however, decreased (P < 0.05) over the duration of the experiment. The hypothesis of the second experiment was that reducing CP in diets for weanling pigs, while still providing AA that meet the requirement will reduce PWD and improve indicators of intestinal function, such as impacting gastrointestinal pH, improving intestinal morphology, and influencing the expression of inflammatory and gut-protective genes, while having no negative effect on pig growth performance. One hundred-eighty weaned pigs (5.53 ± 0.88 kg) were randomly allotted to the 3 treatments with 12 replicate pens per treatment. Results demonstrated that overall BW, ADG, G:F, and diarrhea scores were linearly (P < 0.05) reduced during the 28-d experiment. Serum concentrations of total protein, albumin, peptide YY, and vitamins A and E were the lowest (P < 0.05) on d 13. Pigs fed the 16% CP diet had reduced (P < 0.05) serum albumin concentrations and tended (P < 0.10) to have reduced vitamin E concentrations compared with pigs fed the 22 or 19% CP diets. Serum BUN, haptoglobin, interleukin-1β, and interleukin-6 concentrations were the greatest (P < 0.05) on d 13, whereas serum concentrations of tumor necrosis factor-α and interleukin-10 were the greatest (P < 0.05) on d 6. Villus height and the villus height:crypt depth ratio in the jejunum, and crypt depth in the ileum were improved (P < 0.05) when pigs were fed the diet with 19% CP. In the stomach, pH tended (P < 0.10) to increase with the reduction of dietary CP, whereas in the ileum, pH was reduced (P < 0.05) with the reduction of dietary CP. Expression of interferon-γ, chemokine ligand 9, chemokine ligand 10, occludin, zonula occludens protein-1, trefoil factor-2, trefoil factor-3, mucin-2, GLUT2, and GLUT5 were all decreased (P < 0.05) when pigs were fed the 16% CP diet, whereas expression of transforming growth factor-β was increased when the 16% CP diet was fed instead of the 22 or 19% diets. In conclusion, low CP diets for weanling pigs may be used for the initial post-weaning period to reduce piglet susceptibility to PWD without largely impacting growth performance. If this strategy is to be fed for longer than the initial post-weaning period, meeting the AA requirement becomes crucial to maximizing protein synthesis, which effects both growth performance and maintenance of the gut architecture.
Issue Date:2020-06-11
Rights Information:Copyright 2020 Joseph R. Limbach
Date Available in IDEALS:2020-10-07
Date Deposited:2020-08

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