Abstract
ABSTRACTA total of 864 1-day-old Ross 308 broiler chickens with an average body weight of 40 ± 1.1 g were used to determine the effect of adding protease to broiler chickens diets with different crude protein (CP) density on growth performance, carcase characteristics, excreta microbiota, blood constituents, and nutrient digestibility. The chicks were allotted in pens with 18 birds/pen and 12 pen/treatment. Treatments were T1: basal diet, T2: T1 − 1.0% CP, T3: T2 + 0.05% protease, T4: T2 + 0.1% protease. Results showed that supplementing low CP diets with protease alleviated the negative effects of lowering dietary CP on BWG and FCR (P < .05) on days 1–21. Addition of protease to low CP diets improved BWG on days 1–35 (P < .05). Feeding the chickens with low CP diet reduced (P < .05) digestibility of dry matter (DM), but the addition of protease improved digestibility of DM. The results showed that lowering dietary CP had detrimental influence (P < .05) on digestibility of total essential amino acids (TEAA) and total non-essential amino acids (TNEAA). It is concluded that reduction of dietary CP had a negative effect on broiler chickens and the addition of protease alleviated the negative effects and improved chickens performance.
Highlights
Economic and environmental issues are two major factors affecting commercial animal agriculture
The results showed that lowering dietary crude protein (CP) had detrimental influence (P < .05) on digestibility of total essential amino acids (TEAA) and total nonessential amino acids (TNEAA)
The results showed that the addition of protease to low CP diets improved body weight gain (BWG) significantly (P < .05) and a trend was observed in improving feed conversion ratio (FCR) (P < .06)
Summary
Economic and environmental issues are two major factors affecting commercial animal agriculture. The use of synthetic amino acids and exogenous enzymes has played positive roles in reducing nutrients level of animal diets, especially the crude protein (CP) level, resulting in lower cost of production without excessive excretion of nutrients. It is well-documented that lowering dietary CP level reduced the performance of poultry (Alleman and Leclercq 1997; Mohammadi Gheisar et al 2011). It has been reported that the addition of protease into the diet can significantly improve the digestibility of amino acids (Angel et al 2011; Liu et al 2013). The objective of this study was to determine the influence of addition of a protease to low CP diets on the growth performance, nutrient digestibility, carcase characteristics, and excreta microbiota in broiler chickens
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