Milk yield and composition in dairy cows with post-partum disorders

ABSTRACT This study aimed to determine the impact of different post-partum disorders on milk yield and composition. One hundred and fifteen Holstein cows from a commercial dairy farm located in the state of Rio Grande do Sul in southern Brazil were monitored up to 62 days post-partum. During this period, body condition score evaluation and animal clinical examination were conducted. Percentages of fat, protein, and lactose, as well as somatic cells score, were determined in milk samples. The AST activity and concentrations of NEFA, calcium, and BHBA, were analyzed in blood samples. The occurrence of clinical disorders was identified in 30 (26%) cows. Subclinical disorders were identified in 64 (56%) cows. Only 21 (18%) cows did not suffer any kind of disorder within the studied period. In this study, no significant differences were found in milk production, protein, and somatic cell count in clinical, subclinical, and healthy cows. Milk fat and the fat: protein quotient (F:P) were higher in cows with clinical disorders and the 6 to 21 days in milk, and lactose were lower in cows with clinical disorders and the 22 to 42 days in milk (P<0.05).

摘要 本研究旨在明确不同产后疾病对奶牛产奶量及乳成分的影响。本研究选取巴西南部南里奥格兰德州某商业化奶牛场的115头荷斯坦奶牛（Holstein），对其开展至产后62天的跟踪监测。监测期间，对受试奶牛进行体况评分与临床检查；采集乳样以测定乳脂、乳蛋白、乳糖的百分比含量及体细胞评分，采集血样以分析天冬氨酸转氨酶（AST）活性，以及非酯化脂肪酸（NEFA）、钙和β-羟基丁酸（BHBA）的浓度。研究周期内共有30头（26%）奶牛发生临床型产后疾病，64头（56%）奶牛发生亚临床型产后疾病，仅21头（18%）奶牛未罹患任何类型的产后疾病。本研究未发现临床型、亚临床型患病奶牛与健康奶牛在产奶量、乳蛋白含量及体细胞计数上存在显著差异。但在泌乳天数6至21天时，临床型患病奶牛的乳脂含量及脂蛋比（F:P）显著升高；而在泌乳天数22至42天时，临床型患病奶牛的乳糖含量显著降低（P<0.05）。