Submitted to: Journal of Applied Poultry Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/5/2009
Publication Date: 2/1/2010
Citation: Kidd, M.T., Corzo, A., Dozier, W.A., Araujo, L., Coufal, C.D., Kerr, B.J. 2010. Decreasing Diet Density: Direct Fed Microbials and L-threonine. Journal of Applied Poultry Research. 9(1):5-9. Interpretive Summary: Crystalline threonine has emerged as an opportunistic ingredient in broiler diets to allow dietary crude protein to be reduced to reduce diet costs, yet maintain bird performance provided adequate dietary threonine levels are maintained. However, if dietary crude protein is allowed to drop without considerations as to additionally limiting amino acids (e.g., isoleucine, valine, or argining), bird performance, efficiency of feed utilization, and meat yields can be reduced. In addition, the effects of direct fed microbials have not been clearly evaluated in broiler diets. Consequently, a study was conducted to define the requirement of threonine in growing broilers and whether a direct fed microbial interacted with this requirement. These experiments demonstrated that there was no effect of a direct fed microbial, either by itself or in interaction with dietary threonine, and if dietary threonine is maintined in the diet, that bird performance was not consistently affected, but excretion of nitrogen into the environment would be reduced. This information is important for nutritionists at universities, feed companies, and broiler production facilities showing the importance of threonine levels in broiler diet formulations to maintain optimal bird performance, but reducing the loss of nitrogen into the environment.
Technical Abstract: Alterations in nutritional strategies are becoming more prevalent as broiler integrators are faced with high feed costs compared to historical averages. If broiler diets are devoid of antimicrobials and contain lower than average nutrient content, could the addition of a direct fed microbial ingredient aid in performance recovery? And, although the dietary addition of L-Thr decreases diet cost, will inclusion of up to a pound per ton result in a loss of yield? Two floor pen experiments were conducted to assess the previous questions. In experiment 1, broilers were fed diets varying in amino acid and energy density with and without Primalac from d 1 to 48. Feeding reduced density diets decreased (P<0.05) some live performance measurements and increased (P<0.05) mortality, but interactions or Primalac main effects did not occur (P<0.05). In experiment 2, broiler performance and N excretion were evaluated from 25-43 d of age after birds were fed variations in dietary L-Thr. The dietary inclusion of L-Thr did not decrease bird performance, but reduced (P=0.13) percent N excreted. Although topics addressed in these experiments should be further studied, these results provide possible strategies for integrators to reduce feed costs.