不同日龄略阳乌鸡肉品质对比与最佳上市日龄分析

Comparison of Meat Quality and Analysis of the Best Listing Date of Lueyang Black-bone Chickens at Different Ages

【目的】探究不同日龄略阳乌鸡肌肉营养成分的差异,为确定最佳上市日龄以及科学养殖提供理论支持。【方法】试验以同日出雏的1200只略阳乌鸡为研究对象,随机分为4个重复,每个重复300只。所有鸡42日龄脱温后进行网上笼养,90日龄后为离地网上平养,各阶段的基础饲粮均使用家禽专用饲料,全程自由采食、饮水。记录每周体重,采用Gompertz模型拟合生长曲线;90、120、150日龄时,随机选取体况相近的公、母各8只,采用颈部放血法进行屠宰,采集胸肌,检测不同生长时期胸肌pH、剪切力、水分、干物质、氨基酸、脂肪、蛋白质、肌苷酸和脂肪酸含量。【结果】略阳乌鸡在1~4周体重增长缓慢,4周后进入急速生长期,到17周后体重增长趋势逐渐减缓;Gompertz模型能够很好地拟合略阳乌鸡体重生长曲线,母鸡、公鸡的拟合度均>0.99,拐点体重分别为760.75和940.52 g,拐点周龄分别为8.19和8.49周。母鸡、公鸡的剪切力均随着日龄的增长而逐渐增大,150日龄均极显著高于90和120日龄(P<0.01);母鸡胸肌干物质在150日龄极显著高于90和120日龄(P<0.01)。母鸡胸肌的呈味氨基酸中,谷氨酸(Glu)、丙氨酸(Ala)、天门冬氨酸(Asp)含量在150日龄极显著高于90和120日龄(P<0.01),而酪氨酸(Tyr)的含量在150日龄极显著低于90和120日龄(P<0.05);苏氨酸(Thr)、丝氨酸(Ser)、蛋氨酸(Met)、亮氨酸(Leu)、赖氨酸(Lys)和总氨基酸的含量在150日龄均显著高于90日龄(P<0.05)。公鸡胸肌的呈味氨基酸中,谷氨酸(Glu)、丙氨酸(Ala)、苯丙氨酸(Phe)、胱氨酸(Cys)、脯氨酸(Pro)含量120日龄极显著高于90日龄(P<0.01),酪氨酸(Tyr)、胱氨酸(Cys)、脯氨酸(Pro)和苯丙氨酸(Phe)含量120日龄极显著高于150日龄(P<0.01);组氨酸(His)含量在120日龄最低。120日龄母鸡胸肌的脂肪含量极显著低于150日龄(P<0.01),120日龄母鸡胸肌的蛋白质含量显著低于150日龄(P<0.05)。母鸡胸肌中亚油酸和肉豆蔻酸含量在150日龄极显著高于120日龄(P<0.01),棕榈油酸含量在150日龄极显著低于120日龄(P<0.01)。公鸡胸肌的肌苷酸、棕榈酸(C16∶0)含量120日龄显著高于150日龄(P<0.05),而亚油酸含量150日龄显著高于120日龄(P<0.05)。【结论】随着日龄的增加,略阳乌鸡母鸡营养物质含量逐渐增加;120日龄公鸡胸肌营养物质含量最高,120日龄后随着日龄增加营养物质含量逐渐降低。因此,建议母鸡在120~150日龄之间上市,公鸡在120日龄上市。

【Objective】The purpose of this study was to explore the difference in nutritional composition of Lueyang Black-bone chicken muscles at different ages,providing theoretical support for determining the best listing date and scientific breeding.【Method】1200 Lueyang Black-bone chickens,which were born on the same day,were randomly divided into four replicates,with 300 chickens in each replicate.All chickens were caged on the net after being desuperheated at 42 days of age,and raised off the ground on the net after 90 days of age.The basic diet of each stage was special feed for poultry,and the whole process was free to eat and drink.Weekly body weight was recorded and Gompertz model was used to fit the growth curve.At 90,120,and 150 days of age,8 males and 8 females with similar body conditions were randomly selected and slaughtered by neck bloodletting,the breast muscles were collected to detect pH,shear force,moisture,dry matter,amino acid,fat,protein,inosinic acid and fatty acid content at different growth periods.【Result】The body weight of Lueyang Black-bone chickens increased slowly from 1 to 4 weeks,entered the rapid growth period after 4 weeks,and gradually slowed down after 17 weeks.The Gompertz model could fit the body weight growth curve of Lueyang Black-bone chickens well.The fitting degrees of hens and roosters were both>0.99,the inflection point weight were 760.75 and 940.52 g,and the inflection point weeks old were 8.19 and 8.49 weeks,respectively.The shear force of hens and roosters was increased gradually with the increase of age,and the shear force at 150 days of age was extremely significantly higher than that at 90 and 120 days of age(P<0.01).Breast muscle dry matter of hens at 150 days of age was extremely significantly higher than that at 90 and 120 days of age(P<0.01).The contents of Glu,Ala,and Asp in the flavoring amino acids in breast muscle of hens at 150 days of age were extremely significantly higher than that at 90 and 120 days of age(P<0.01),while the content of Tyr at 150 days of age was significantly lower than that at 90 and 120 days of age.The contents of Thr,Ser,Met,Leu,Lys and the total amount of amino acids at 150 days of age were significantly higher than those at 90 days of age(P<0.05).The contents of Glu,Ala,Phe,Cys,Pro in the flavor amino acids of rooster breast muscle at 120 days of age were extremely significantly higher than those at 90 days of age(P<0.01),while the contents of Tyr,Cys,Pro and Phe at 120 days of age were extremely significantly higher than those at 150 days of age(P<0.01),the content of His was the lowest at 120 days of age.The fat content of breast muscle of 120-day-old hens was extremely significantly lower than that of 150-day-old hens(P<0.01),and the protein content of breast muscle of 120-day-old hens was significantly lower than that of 150-day-old hens(P<0.05).The contents of C18∶2n6c and C14∶0 in breast muscle of hens at 150 days of age were extremely significantly higher than those at 120 days of age(P<0.01),and the content of C16∶1 at 150 days of age was extremely significantly lower than that at 120 days of age(P<0.01).The contents of inosinic acid and C16∶0 in rooster breast muscle at 120 days of age were significantly higher than that at 150 days of age(P<0.05),while the content of C18∶2n6c at 150 days of age was significantly higher than that at 120 days of age(P<0.05).【Conclusion】The nutrient contents of hens were gradually increased with the increase of age.The nutrient content of breast muscle of 120-day-old cock was the highest,and the nutrient contents were decreased gradually with the increase of day age after 120-day-old.Therefore,it was recommended that hens should be listed between 120 and 150 days of age,and roosters should be listed at 120 days of age.