ABSTRACT

1. Gradual feed restriction was applied to broilers in order to reduce growth rate and, as a consequence, gradually impacts wooden breast myopathy occurrence. Ultrasound (US) images of breast muscle in live birds were correlated with breast fillets presenting wooden breast characteristics (WB).

2. A total of 1800 Cobb × Cobb 500 slow-feathering male chicks were fed one of the six feed restriction treatments with 12 replicates of 25 birds each, in a completely randomised design. Birds were fed ad libitum or were pair-fed to 50%, 60%, 70%, 80% or 90% of normal ad libitum intakes from 8 to 49 d to provide a gradual reduction in growth rate. Ultrasound images were obtained weekly from all birds and, in parallel, one bird per pen was weekly slaughtered and the major breast muscle was weighed and WB graded as 0 (normal), 1 (mild hardening in the upper), 2 (moderate hardening in the upper and/or lower), 3 (severe hardening) and 4 (severe hardening with haemorrhagic lesions and yellow fluid). Blood was taken for analysis of enzymes related to muscle cell breakdown.

3. Feed restriction applied at 50%, 60%, 70%, 80% and 90% of the ad libitum feed intake (FI) resulted in decreased body weight gain (BWG; P ≤ 0.05).

4. From 21 to 49 d, the increasing feed restriction led to linear increases (P ≤ 0.05) in WB scores, fibre density as well as breast depth and breast echogenicity. Creatine kinase, lactate dehydrogenase and aspartate aminotransferase concentration decreased linearly when broilers were feed restricted (P ≤ 0.05).

5. Wooden breast was positively correlated with echogenicity at 21 d (r = 0.510), 28 (r = 0.531), 35 (r = 0.470), 42 (r = 0.430) and 49 d (r = 0.548) (P ≤ 0.001). The use of breast echogenicity can be an additional tool to early detect alterations related to wooden breast.

摘要

1.逐渐限制肉鸡的生长，以降低其生长速度，从而逐渐影响木质乳腺肌病的发生。活禽中胸肌的超声（美国）图像与呈现木制乳腺特征（WB）的胸片相关。

2.在完全随机设计中，对六只饲料限制处理之一的总共1800只Cobb×Cobb 500羽慢羽雄性小鸡进行喂养，每只重复12次，每组25只。随意喂食鸟类或成对喂饲8至49天的正常随意摄入量的50％，60％，70％，80％或90％，以逐渐降低生长速度。每周从所有鸡身上获取超声图像，平行地，每周每只鸡宰杀一只鸟，称重主要胸肌，WB分为0（正常），1（上部轻度硬化），2（中等硬度）。上部和/或下部），3（严重硬化）和4（严重硬化并伴有出血性病变和黄色液体）。抽取血液用于分析与肌肉细胞分解有关的酶。

3.以任意采食量（FI）的50％，60％，70％，80％和90％施加饲料限制导致体重增加减少（BWG； P≤0.05）。

4.从21天到49天，饲料限制的增加导致WB评分，纤维密度，乳房深度和乳房回声性线性增加（P≤0.05）。当肉鸡饲喂受限时，肌酸激酶，乳酸脱氢酶和天冬氨酸转氨酶的浓度线性下降（P≤0.05）。

5.在21 d（r = 0.510），28（r = 0.531），35（r = 0.470），42（r = 0.430）和49 d（r = 0.548）时，木质乳房与回声成正相关（P≤0.001） ）。乳房回声的使用可以是早期发现与木制乳房有关的变化的附加工具。