China Animal Husbandry and Veterinary Medicine ›› 2023, Vol. 50 ›› Issue (1): 134-142.doi: 10.16431/j.cnki.1671-7236.2023.01.014

• Nutrition and Feed • Previous Articles     Next Articles

Dietary Threonine Requirement of Yellow-feathered Broilers Aged From 22 to 42 Days

LIN Xiajing, ZHENG Chuntian, XI Pengbin, CHENG Zhonggang, DING Fayuan, RUAN Dong, WANG Yibing, JIANG Shouqun   

  1. State Key Laboratory of Livestock and Poultry Breeding, Key Laboratory of Animal Nutrition and Feed Science in South China, Ministry of Agriculture and Rural Affairs, Guangdong Key Laboratory of Animal Breeding and Nutrition, Institute of Animal Science, Guangdong Academy of Agricultural Sciences, Guangzhou 510640, China
  • Received:2022-07-25 Online:2023-01-05 Published:2023-01-04

Abstract: 【Objective】 This experiment was conducted to investigate the effects of dietary threonine(THR)level on growth performance, carcass quality and immune function of Yellow-feathered broilers aged from 22 to 42 days, and to determine their appropriate THR requirement.【Method】 A total of 1 600 22-day-old fast-growing Lingnan Yellow-feathered broilers were randomly divided into 5 groups with 8 replicates per group and 40 chickens (male and female half) per replicate according to the same body weight.Chickens in the 5 treatment groups were fed diets containing 0.55% (basal diet), 0.62%, 0.69%, 0.76% or 0.83% THR, respectively.A corn-peanut meal basal diet was adopted, and the experiment lasted for 21 days.At the end of the test, 2 chickens were selected for slaughter sampling in each repetition to determine slaughter performance, immune organ index and serum biochemical indicators.【Result】 Dietary THR level significantly affected body weight(BW), average daily gain (ADG) and feed/gain (F/G)(P<0.05).For female broilers, ADG of 0.88% THR group was the highest, and average daily feed intake (ADFI) of 0.81% THR level group was the highest.For male broilers, ADG of 0.81% THR group was the highest, and ADFI of 0.81% THR level group was the highest.There was a significant quadratic linear correlation between dietary THR level and ADG, ADFI of Yellow-feathered males and F/G of both males and females (P<0.05).According to the regression equation of ADF and ADFI, the optimal dietary THR level of Yellow-feathered male broilers was 0.81% and 0.83%, respectively.According to the regression equation of F/G, the optimal dietary THR level of Yellow-feathered male broilers was 0.83% and 0.86%, respectively.Dietary THR level had no significant effects on eviscerated percentage, half-eviscerated percentage, leg muscle percentage and breast muscle percentage of Yellow-feathered males and females (P<0.05).There were significant effects on eviscerated percentage and abdominal fat percentage of Yellow-feathered male broilers, the abdominal fat percentage in 0.81% THR group was significantly lower than that in 0.60% and 0.74% THR groups, and the abdominal fat percentage in 0.88% THR group was significantly lower than that in 0.60% and 0.67% THR groups (P<0.05).Dietary THR level significantly affected bursa of Fabricius index and thymus index of Yellow-feathered females, the bursa of Fabricius index in 0.60% THR group was significantly lower than that in 0.81% THR group, and the thymus index in 0.81% and 0.88% THR groups were significantly higher than that in 0.60% THR group (P<0.05), but had no significant effects on liver index and spleen index (P>0.05).Dietary THR level had significant effects on serum triglyceride and insulin contents of Yellow-feathered female broilers, serum insulin content of 0.60% THR level group was the lowest, the serum triglyceride content in 0.88% THR level group was the lowest, significantly lower than 0.60% THR level group (P<0.05).Dietary THR level significantly affected the triglyceride content of Yellow-feathered male broilers, and 0.88% THR level group had the lowest serum triglyceride content, significantly lower than 0.60% and 0.67% THR level groups (P<0.05).【Conclusion】 Appropriate dietary THR could improve the growth performance, carcass quality and immune organ development of Yellow-feathered broilers.The optimal THR level for Yellow-feathered male and female broilers aged from 22 to 42 days were determined to be 0.83% and 0.81% respectively based on growth performance, the daily requirement of threonine for male and female broilers were 0.59 g and 0.51 g, respectively.

Key words: Yellow-feathered broilers; threonine; growth performance; carcass quality; nutrient requirement

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