China Animal Husbandry and Veterinary Medicine ›› 2025, Vol. 52 ›› Issue (4): 1543-1553.doi: 10.16431/j.cnki.1671-7236.2025.04.009

• Nutritionand Feed • Previous Articles     Next Articles

Study on the Appropriate Dietary Crude Protein Level of Yanjin Black-bone Chickens

ZHANG Zhengfei1, TANG Anxing1, SUN Jindong1, FU Lixiang1, WANG Xingxian1, ZHANG Shiyun1, YANG Liangyu2, NIU Guoyi1, TAO Linli1   

  1. 1. Yunnan Key Laboratory of Animal Nutrition and Feed, Faculty of Animal Science and Technology, Yunnan Agricultural University, Kunming 650201, China;
    2. College of Veterinary Medicine, Yunnan Agricultural University, Kunming 650201, China
  • Received:2024-09-18 Published:2025-03-29

Abstract: 【Objective】 The experiment was conducted to study the effects of dietary crude protein level on growth performance,blood biochemical indexes and nutrient utilization of Yanjin Black-bone chickens,and to determine the appropriate dietary crude protein level.【Method】 A total of 200 one-day-old Yanjin Black-bone chickens with similar body weight and health were randomly divided into 5 groups with 5 replicates in each group and 8 chickens in each replicate (half male and half female),and the diets were fed with crude protein levels of 17.40%,18.70%,20.00%,21.30% and 22.60%,respectively (17.40% CP,18.70% CP,20.00% CP,21.30% CP and 22.60% CP groups).During the experiment,the average daily gain (ADG),average daily feed intake (ADFI) and feed to gain ratio (F/G) were calculated.Metabolic tests were carried out on days 36-39 to determine total energy,crude protein,and amino acid. On the 43rd day of the experiment,2 chickens in each replicate were selected for blood sampling and slaughter to determine serum biochemical indexes and body composition.【Result】 Dietary crude protein level had no significant effects on initial body weight,final body weight,ADG,ADFI and F/G (P>0.05),but the final body weight increased first and then decreased with the increase of dietary crude protein level (P=0.095),and the highest final body weight was obtained when the dietary crude protein level was 20.00%.The protein deposition rate of 17.40% CP and 18.70% CP groups was significantly higher than that of 20.00% CP,21.30% CP and 22.60% CP groups (P<0.05).The deposition rates of 8 essential amino acids except lysine and methionine showed a significant downward trend with the increase of dietary crude protein level (P<0.05),and all of them decreased linearly and quadratically with the increase of dietary crude protein level (P<0.05). The nitrogen intake and fecal nitrogen increased linearly and quadratically with the increase of dietary crude protein level (P<0.05), and nitrogen utilization rate decreased linearly and quadratically with the increase of dietary crude protein level (P<0.05). The serum uric acid content of chickens in 21.30% CP and 22.60% CP groups were significantly higher than that in 17.40% CP and 18.70% CP groups, and increased linearly and quadratically with the increase of dietary crude protein level (P<0.05). 【Conclusion】 The recommended dietary crude protein level for Yanjin Black-bone chicken was 20.00%.

Key words: Yanjin Black-bone chickens; dietary crude protein level; growth performance; blood biochemical index; nutrient utilization

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