Abstract Expansion of the Irish dairy herd has led to more dairy breed male calves being available for beef production. This study investigated the physico-chemical and sensory characteristics of beef from Holstein-Friesian (HF) and Jersey × HF (JEX) young bulls fed pasture grass only or pasture grass plus 2 kg concentrate during their first grazing season and slaughtered at 15, 19 or 22 mo of age. Longissimus thoracis (LT) muscles were collected from 67 carcasses. Postmortem pH, ultimate pH (pHu), meat colour, chemical composition, collagen content and solubility were evaluated. After ageing for 21 d, Warner-Bratzler shear force and cooking loss were determined, and assessments by a trained sensory panel were conducted. Meat from older animals was darker. The pHu, moisture and ash contents decreased, while residual roast beef flavour length increased with age. However, increasing age to slaughter did not negatively influence tenderness. JEX beef had lower cooking loss, was darker and redder, in addition to having higher sensory scores for initial tenderness and fattiness than HF beef. Warner-Bratzler variables were positively correlated with cooking loss and chewiness and were negatively correlated with intramuscular fat (IMF) content, soluble collagen and initial tenderness. In summary, most young dairy bull beef samples were acceptably tender after 21 d of ageing and half of them had acceptable IMF content. Slaughter age affected beef colour, pHu, chemical composition and flavour length. The eating quality of meat from the JEX breed type was considered to be superior to that of the HF breed type. Diet during the first season had no effect on meat quality traits.

中文翻译：

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来自两个不同生产系统的三个年龄的两个品种类型的年轻奶牛的牛肉的食用质量

摘要 爱尔兰奶牛群的扩张导致更多的奶牛公牛犊可用于牛肉生产。本研究调查了荷斯坦 - 弗里斯兰 (HF) 和泽西 × HF (JEX) 年轻公牛在第一个放牧季节只饲喂牧草或牧草加 2 kg 精料并在 15、19 日屠宰的牛肉的理化和感官特征或 22 个月。从 67 具尸体收集胸最长肌 (LT) 肌肉。评估了死后 pH、最终 pH (pHu)、肉颜色、化学成分、胶原蛋白含量和溶解度。老化 21 天后，测定 Warner-Bratzler 剪切力和烹饪损失，并由经过培训的感官小组进行评估。老年动物的肉颜色较深。pHu、水分和灰分含量降低，而残留的烤牛肉风味长度随着年龄的增长而增加。然而，增加屠宰年龄并未对嫩度产生负面影响。与 HF 牛肉相比，JEX 牛肉具有较低的烹饪损失，颜色更深、更红，而且初始嫩度和脂肪含量的感官评分更高。Warner-Bratzler 变量与烹饪损失和咀嚼度呈正相关，与肌内脂肪 (IMF) 含量、可溶性胶原蛋白和初始柔软度呈负相关。总之，大多数年轻的奶牛牛肉样品在老化 21 d 后嫩度尚可，其中一半的 IMF 含量可以接受。屠宰年龄影响牛肉的颜色、pHu、化学成分和风味长度。JEX 品种的肉食质量被认为优于 HF 品种类型的肉。