by Juan C. Suarez || Ph.D. candidate
In recent years, the use of vegetarian diets combined with antibiotic free (ABF) production has created profitable opportunities for integrators. However, this approach can result in multiple challenges that can impact bird health and performance, such as coccidiosis, necrotic enteritis, pododermatitis, wet litter and increased ammonia production.
The quality and composition of feed play a critical role in litter quality; the two are irrevocably linked. With increasingly more integrators moving to veggie fed diets, it’s vital to understand how litter conditions are impacted by diet in order to mitigate the potentially detrimental effects.
Veggie fed diets can be higher in crude protein, causing higher ammonia production. Reductions in ammonia challenge from a nutrional approach can be accomplished through:
- careful and precise diet formulation
- reduced crude protein levels
- addition of synthetic amino acids
Reducing protein levels by one percentage point can result in a 10% reduction in ammonia emissions. Supplementation with synthetic amino acids has been shown to significantly reduce N excretions. Careful consideration should be given to glycine + serine levels in veggie diets. The use of enzymes like xylanases, β-glucanase, or β-mannanase in order to increase digestibility has a valuable place also in veggie fed programs. A 25% increase in N digestibility can be achieved with enzyme supplementation in broiler diets1.
The Relationship between Diet, Litter Moisture and Ammonia
Ammonia detected in commercial poultry houses comes from the birds themselves. Unused nitrogen is excreted as uric acid, ammonia, and urea. Ammonia (NH3) is a colorless, water-soluble gas formed by the bacterial breakdown of uric acid in the litter.
Veggie diets generally rely on soybean meal to deliver the major portion of necessary protein, which by itself can cause enteric challenges. Despite soybean meal’s rich amino acid profile, it also contains a relatively high concentration of poorly digestible oligosaccharides; those oligosaccharides have been associated with wet litter issues and sticky droppings that result in pododermatitis2.
The Link: Veggie Diets, Wet Litter, Footpad Dermatitis
Research has clearly shown how veggie diets are correlated with wet litter and therefore an increased risk of pododermatitis (footpad dermatitis)—a costly condition in commercial poultry operations.
Increased litter moisture and incidence and severity of footpad dermatitis on birds fed veggie diets compared to birds fed diets containing 10% poultry by-product meal or 6 to 7% corn gluten meal in the starter and grower diets, respectively.3
A three-fold increase in severe pododermatitis lesions in veggie-fed broilers as well as significantly higher ammonia in the litter has been reported when compared to a corn-SBM formula containing animal protein.3
Veggie Diets Require Proactive Management
Due to animal welfare and economic factors, ammonia concentrations and the incidence and severity of pododermatitis in commercial poultry are of great concern. Since nutrition can play a significant role in both, a proactive approach must be used to identify and implement appropriate nutrional and management strategies for veggie-fed/ABF production.
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2Greenwood, M. 2015. Nutritional Strategies for Broilers Fed Vegetarian and Antibiotic-Free Diets.
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