本试验旨在研究饲粮粗蛋白(CP)和赖氨酸水平对生长性能的影响,屠宰性能,肉质,和生长缓慢的鸡的肌纤维特性。安排了3×3阶乘实验,鸡饲喂3个水平的日粮CP(16.0%,17.0%,18.0%)和3个水平的日粮赖氨酸(0.69%,0.84%,0.99%)。将540只8周龄北京优鸡(BYC)雌性生长鸡随机分为9组,每组重复5次,和12只鸡每个重复。将鸟类随机分配到9种实验饮食中的一种。增长业绩,屠宰性能,肉质,并在16周龄时确定肌纤维特征。结果表明,饲粮CP水平以及饲粮CP和赖氨酸水平的交互作用影响平均采食量(AFI)(p<0.05)。16.0%CP和17.0%CP组的AFI高于18.0%CP组(p<0.05)。饮食CP水平在9至16周时显著影响体重增加(BWG)(p<0.05)。18.0%CP组的BWG最高(93.99g)。饮食CP水平影响腿部肌肉产量的百分比,16.0%CP组的腿部肌肉产量百分比显著低于其他两组(p<0.05)。膳食CP和赖氨酸水平单独及其相互作用不影响pH24h,滴水损失,和乳房肌肉的烹饪损失(p>0.05)。18.0%CP组的剪切力(29.55N)高于其他两组(p<0.01)。饲粮CP水平影响肌纤维特性(p<0.01),在18.0%CP水平下,肌纤维密度最低(846.35p·mm-2),肌纤维直径最大(30.92μm)。日粮赖氨酸水平影响肌纤维直径,内膜厚度,包膜厚度(p<0.01),在0.84%赖氨酸水平下获得的最大肌纤维直径(29.29μm),在0.69%赖氨酸水平下,最大的内膜厚度(4.58μm),以及在0.99%赖氨酸水平下最大的包膜厚度(9.26μm)。肌纤维密度与肌纤维直径、肌层厚度呈负相关(R=-0.883,R=-0.523,p<0.01);膜层厚度与剪切力呈显著负相关(R=-0.682,p<0.05)。因此,降低饲粮CP水平,添加适当的赖氨酸可以降低肌纤维直径,增加膜层厚度,减少剪切力,提高肉的嫩度。低CP(16.0%)日粮中的高赖氨酸水平(0.99%)可以通过调节肌纤维特性来提高肉的嫩度,而不会影响生产性能。
This study aimed to investigate the effects of dietary crude protein (CP) and
lysine levels on growth performance, slaughter performance, meat quality, and myofiber characteristics of slow-growing chicken. A 3 × 3 factorial experiment was arranged, and the chickens were fed with 3 levels of dietary CP (16.0%, 17.0%, 18.0%) and 3 levels of dietary
lysine (0.69%, 0.84%, 0.99%). A total of 540 8-week-old Beijing-You Chicken (BYC) female growing chickens were randomly allocated to 9 groups, 5 replicates per group, and 12 chickens per replicate. The birds were randomly allocated to one of the 9 experimental diets. Growth performance, slaughter performance, meat quality, and myofiber characteristics were determined at 16 weeks of age. The results showed that dietary CP level and the interaction of dietary CP and
lysine levels affected average feed intake (AFI) (p < 0.05). The AFI in the 16.0% CP and 17.0% CP groups was higher than in the 18.0% CP group (p < 0.05). Dietary CP levels significantly affected body weight gain (BWG) (p < 0.05) at 9 to 16 weeks. The 18.0% CP group had the highest BWG (93.99 g). Dietary CP levels affected the percentage of leg muscle yield, and the percentage of leg muscle yield of the 16.0% CP group was significantly lower than that in the other two groups (p < 0.05). Dietary CP and lysine levels alone and their interactions did not affect pH24h, drip loss, and cooking loss of breast muscle (p > 0.05). The shear force of the 18.0% CP group (29.55 N) was higher than that in the other two groups (p < 0.01). Dietary CP level affected myofiber characteristic (p < 0.01), with the lowest myofiber density (846.35 p·mm-2) and the largest myofiber diameter (30.92 μm) at 18.0% CP level. Dietary
lysine level affected myofiber diameter, endomysium thickness, perimysium thickness (p < 0.01), with the largest myofiber diameter (29.29 μm) obtained at 0.84% lysine level, the largest endomysium thickness (4.58 μm) at 0.69%
lysine level, and the largest perimysium thickness (9.26 μm) at 0.99%
lysine level. Myofiber density was negatively correlated with myofiber diameter and endomysium thickness (R = -0.883, R = -0.523, p < 0.01); perimysium thickness had a significant negative correlation with shear force (R = -0.682, p < 0.05). Therefore, reducing dietary CP level and adding appropriate lysine can reduce myofiber diameter and increase perimysium thickness, reducing shear force and improving meat tenderness. A high lysine level (0.99%) in the low-CP (16.0%) diet can improve meat tenderness by regulating the myofiber characteristic without affecting production performance.