Institute of Animal Science, Chinese Academy of Agricultural Sciences, Beijing 100193, P. R. China.
Poult Sci. 2012 Jan;91(1):237-47. doi: 10.3382/ps.2011-01667.
This paper, the second from a comprehensive study, describes the effects of varying growth rate by feeding at different planes of nutrition with a constant ME:CP ratio on muscle characteristics and meat quality in 2 distinct broiler breeds of male chickens (Arbor Acres, a commercial line; and Beijing-You, a Chinese nonimproved line). Experimental diets, differing on average by 2% CP, were formulated with high-, medium-, or low-nutrient densities for 3 growing phases. Male hatchlings (216 of each breed) were randomly assigned to 6 pens of 12 birds in each treatment. Altered histological characteristics of muscle fibers, early postmortem muscle metabolism, and meat quality were investigated in the pectoralis major and biceps femoris. At their market age, Arbor Acres broilers had significantly higher concentrations of plasma protein and lipid metabolites, ratios of white to red and intermediate fibers, pH, L* and b* values, and lower concentrations of plasma glucose metabolites, muscle-fiber diameter, muscle contents of energy stores, a* value, drip loss, and shear force than the values found for the Beijing-You chickens (P < 0.01). Higher nutrient density increased the size of the muscle fibers, decreased glycogen reserve, and reduced the rate and extent of acidification in the Arbor Acres chickens, while accelerating transformation of red and intermediate-to-white fibers, enhancing energy stores, and hastening the decrease in pH postmortem in the Beijing-You chickens (P < 0.05). In each breed, most meat quality variables (e.g., shear force, drip loss, and color) were consistent with the histological and biochemical changes caused by the feeding strategy. Together, dietary nutrient density can influence meat quality as a result of altered histological and initial energy and metabolic characteristics of the muscle. Many of the responses to diet are breed and tissue dependent in broiler chickens.
本文是一项综合研究的第二部分，描述了在恒定 ME：CP 比的情况下，以不同的营养平面喂养以改变生长速度对 2 种不同肉鸡品种（阿伯考克斯，商业品系；北京油鸡，中国非改良品系）肌肉特性和肉质的影响。实验日粮在 3 个生长阶段以平均相差 2%CP 的方式配制，具有高、中、低营养密度。雄性雏鸡（每个品种 216 只）随机分配到每个处理的 6 个 12 只鸡的栏中。在胸大肌和股二头肌中研究了肌肉纤维的组织学特征、宰后早期肌肉代谢和肉质的变化。在市场年龄时，阿伯考克斯肉鸡的血浆蛋白和脂质代谢物浓度、白纤维与红纤维和中间纤维的比例、pH 值、L和 b值显著高于北京油鸡（P<0.01），而血浆葡萄糖代谢物、肌纤维直径、肌肉能量储存含量、a*值、滴水损失和剪切力则较低。较高的营养密度增加了肌肉纤维的大小，降低了糖原储备，减少了阿伯考克斯肉鸡的酸化速度和程度，同时加速了红纤维和中间纤维向白纤维的转化，增加了能量储存，加快了北京油鸡宰后 pH 值的下降（P<0.05）。在每个品种中，大多数肉质变量（如剪切力、滴水损失和颜色）与喂养策略引起的组织学和生化变化一致。总之，日粮营养密度可以通过改变肌肉的组织学和初始能量和代谢特性来影响肉质。许多对饮食的反应在肉鸡中是品种和组织依赖性的。
