Use of protease enzyme in diets with different levels of protein and amino acids on performance, carcass characteristics, nutrient digestibility and some blood parameters concentrations in broiler chicks

Document Type : Research Paper

Authors

1 Department of Animal Science, College of Animal Sciences and Fisheries, Sari Agricultural Sciences and Natural Resources University, Sari, Iran

2 Department of Animal Sciences, College of Animal Sciences and Fisheries, Sari Agricultural Sciences and Natural Resources University, Sari, Iran

Abstract

A total of 240 male Ross 308 broiler chicks were allocated in completely randomized design, including six experimental diets with 4 replicates and 10 chicks per replicate. Experimentaldiets include 1- a control diet based on corn and soybean meal, recommended according to the guide of Ross strain (308) 2- a control diet with the addition of protease enzyme with recommended levels (0/02 %) 3- low protein diet (five percent reduction) 4- Diet with low levels of protein and essential amino acids (five percent reduction) 5- Diet with low levels of protein (experimental diet three) with the addition of protease enzyme with recommended levels (0/02 %) 6- Diet with low levels of protein and essential amino acids with the addition of protease enzyme with recommended levels (0/02 %).The highest amount of feed consumption in the starter  period and the highest feed conversion ratio  in the growth period, as well as the highest percentage of abdominal fat, were related to the diet with low levels of protein and amino acids. Protease enzyme increased the body weight and decreased the feed conversion ratio during the growth period in diets with low levels of protein and amino acids (P<0.05).The use of protease enzyme in diets with low protein levels improved the digestibility of dry matter and organic matter, and the highest percentage of thigh and spleen and blood HDL concentration was related to the diet with low protein levels with the addition of protease enzyme (P<0.05). Based on the results, use of protease enzyme in diets with low levels of protein and amino acid improved the performance of broiler chickens.

Keywords

Main Subjects

Extended Abstract

Introduction

    Protein is one of the expensive nutrient in broiler diets. One strategy for reducing of the cost of broiler chicks is to reduce of diet protein by supplementation of protease enzyme. In this research, the effect of using protease enzyme in diets with different levels of protein and amino acids on performance, carcass characteristics, nutrient digestibility some blood parameters concentrations in broiler chicks was investigated.

 

Materials and methods

    A total of 240 male Ross 308 broiler chicks were allocated in completely randomized design, including six experimental diets with 4 replicates and 10 chicks per replicate. Experimental diets include 1- a control diet based on corn and soybean meal, recommended according to the guide of Ross strain (308) 2- a control diet with the addition of protease enzyme with recommended levels (0/02 %) 3-low protein diet (five percent reduction) 4- Diet with low levels of protein and essential amino acids (five percent reduction) 5- Diet with low levels of protein (Experimental dietthree) with the addition of protease enzyme 6- Diet with low levels of protein and essential amino acids with the addition of protease enzyme. Diets containing enzymes in this experiment were supplemented with 0.02% (based on the manufacturer's recommendation) serine protease enzyme (RONOZYME ProAct, DSM Animal Nutrition & Health, Switzerland) The experimental period included starter (0 - 10 days old) and growth periods (11 - 24 days old). On the 21st day of the experiment, in order to study the effect of the experimental diets on the biochemical indices of blood serum, two pieces of birds from each experimental unit were randomly selected and blood was taken from the vein under their wing. Amounts of glucose, triglycerides, cholesterol, high-density lipoprotein (HDL-c), low-density lipoprotein (LDL-c) and very low-density lipoprotein (VLDL-c) using special kits or relevant formulas were measured. In order to evaluate the carcass and internal organs, at the end of the experimental period (age 25 days), after about six hours of starvation, the number of two birds from each experimental unit (eight birds for each experimental diet) with a body weight close to the average weight of the experimental unit were selected and killed after weighing. Then the whole carcass, breast, thighs and other parts of the carcass were separated and the relative weight of the carcass was calculated as a ratio of the live weight and the weight of other parts as a ratio of the carcass weight.

 

Results

    The highest amount of feed consumption in the starter period was related to diet 4 (diet with low levels of protein and amino acid) (P<0.05). Adding 0.02 percent of protease enzyme to the diet with low levels of protein and amino acid improved the amount of weight gain of the birds during the growth period and the whole rearing period. Supplementing the diet with low levels of protein and amino acid with protease enzyme during the growth period improved the feed conversion ratio (P<0.05). The highest and most unfavorable feed conversion ratio in the growth period and the entire rearing period was observed in birds fed with diet with low levels of protein and amino acid (experimental diet4), which was significantly different from other groups (P<0.05). The highest dry matter and organic matter digestibility were related to experimental diet 5 (diet with low protein levels with the addition of protease enzyme) (P<0.05). Addition of enzyme to diets with low levels of amino acid and protein improved the digestibility of protein (P<0.05).The effect of different experimental groups on the percentage of carcass components was significant (P<0.05). The highest breast weight ratio was observed in the control group supplemented with protease enzyme (experimental diet2) (P<0.05). The highest percentage of thigh weight was related to experimental diet 5 (diet with low levels of protein with addition of protease enzyme). The highest abdominal fat weight was related to diet 4 (diet with low protein and amino acid levels). The highest liver weight was related to experimental diet 4 (diet with low protein and amino acid levels without protease enzyme) and the highest heart weight was related to diet 2 (control diet with protease enzyme). Also, the highest spleen weight was related to experimental diet5 (diet with low protein levels with the addition of protease enzyme). Supplementing the diet with low levels of protein with protease enzyme increased the amount of HDL-c in the blood. In general, the findings of this research showed that the addition of protease enzyme to diets with low protein and amino acid levels significantly improved weight gain (in the growth period and the entire test period) and feed conversion ratio (growth period). Also, the enzyme increased the digestibility of dry matter, crude protein and organic matter in diets with low protein levels and increased the percentage of breast weight.

 

Conclusion

    Based on the results of the present experiment, use of protease enzyme in diets with low levels of protein and amino acid improved the performance of broiler chicks.    

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Iranian Journal of animal Science
Volume 55, Issue 1
March 2024
Pages 163-180

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  • Receive Date: 29 December 2022
  • Revise Date: 03 June 2023
  • Accept Date: 03 June 2023

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