Antanaitis Ramūnas, Džermeikaitė Karina, Januškevičius Vytautas, Šimonytė Ieva, Baumgartner Walter
Large Animal Clinic, Veterinary Academy, Lithuanian University of Health Sciences, Tilžės Str. 18, LT-47181 Kaunas, Lithuania.
Brolis Sensor Technology, Molėtų Str. 73, LT-14259 Vilnius, Lithuania.
Animals (Basel). 2023 Oct 21;13(20):3293. doi: 10.3390/ani13203293.
This study endeavors to ascertain alterations in the in-line registered milk fat-to-protein ratio as a potential indicator for evaluating the metabolic status of dairy cows. Over the study period, farm visits occurred biweekly on consistent days, during which milk composition (specifically fat and protein) was measured using a BROLIS HerdLine in-line milk analyzer (Brolis Sensor Technology, Vilnius, Lithuania). Clinical examinations were performed at the same time as the farm visits. Blood was drawn into anticoagulant-free evacuated tubes to measure the activities of GGT and AST and albumin concentrations. NEFA levels were assessed using a wet chemistry analyzer. Using the MediSense and FreeStyle Optium H systems, blood samples from the ear were used to measure the levels of BHBA and glucose in plasma. Daily blood samples were collected for BHBA concentration assessment. All samples were procured during the clinical evaluations. The cows were categorized into distinct groups: subclinical ketosis (SCK; n = 62), exhibiting elevated milk F/P ratios without concurrent clinical signs of other post-calving diseases; subclinical acidosis (SCA; n = 14), characterized by low F/P ratios (<1.2), severe diarrhea, and nondigestive food remnants in feces, while being free of other post-calving ailments; and a healthy group (H; n = 20), comprising cows with no clinical indications of illness and an average milk F/P ratio of 1.2. The milk fat-to-protein ratios were notably higher in SCK cows, averaging 1.66 (±0.29; < 0.01), compared to SCA cows (0.93 ± 0.1; < 0.01) and healthy cows (1.22). A 36% increase in milk fat-to-protein ratio was observed in SCK cows, while SCA cows displayed a 23.77% decrease. Significant differences emerged in AST activity, with SCA cows presenting a 26.66% elevation ( < 0.05) compared to healthy cows. Moreover, SCK cows exhibited a 40.38% higher NEFA concentration ( < 0.001). A positive correlation was identified between blood BHBA and NEFA levels (r = 0.321, < 0.01), as well as a negative association between BHBA and glucose concentrations (r = -0.330, < 0.01). Notably, AST displayed a robust positive correlation with GGT (r = 0.623, < 0.01). In light of these findings, this study posits that milk fat-to-protein ratio comparisons could serve as a non-invasive indicator of metabolic health in cows. The connections between milk characteristics and blood biochemical markers of lipolysis and ketogenesis suggest that these markers can be used to check the metabolic status of dairy cows on a regular basis.
本研究旨在确定在线记录的乳脂肪与蛋白质比例的变化，作为评估奶牛代谢状态的潜在指标。在研究期间，每隔一周的固定日期进行农场走访，在此期间使用BROLIS HerdLine在线牛奶分析仪（Brolis传感器技术公司，立陶宛维尔纽斯）测量牛奶成分（特别是脂肪和蛋白质）。在农场走访的同时进行临床检查。将血液采集到无抗凝剂的真空采血管中，以测量γ-谷氨酰转移酶（GGT）和天冬氨酸转氨酶（AST）的活性以及白蛋白浓度。使用湿化学分析仪评估非酯化脂肪酸（NEFA）水平。使用美迪信（MediSense）和FreeStyle Optium H系统，采集耳部血液样本以测量血浆中β-羟基丁酸（BHBA）和葡萄糖水平。每天采集血液样本用于评估BHBA浓度。所有样本均在临床评估期间采集。奶牛被分为不同的组：亚临床酮病组（SCK；n = 62），表现为乳脂肪与蛋白质比例升高，且无其他产后疾病的并发临床症状；亚临床酸中毒组（SCA；n = 14），其特征为脂肪与蛋白质比例低（<1.2）、严重腹泻且粪便中有未消化的食物残渣，同时无其他产后疾病；以及健康组（H；n = 20），包括无疾病临床指征且平均乳脂肪与蛋白质比例为1.2的奶牛。与SCA奶牛（0.93±0.1；<0.01）和健康奶牛（1.22）相比，SCK奶牛的乳脂肪与蛋白质比例显著更高，平均为1.66（±0.29；<0.01）。SCK奶牛的乳脂肪与蛋白质比例增加了36%，而SCA奶牛则下降了23.77%。AST活性存在显著差异，与健康奶牛相比，SCA奶牛的AST活性升高了26.66%（<0.05）。此外，SCK奶牛的NEFA浓度高出40.38%（<0.001）。血液中BHBA与NEFA水平之间存在正相关（r = 0.321，<0.01），BHBA与葡萄糖浓度之间存在负相关（r = -0.330，<0.01）。值得注意的是，AST与GGT之间呈现出强正相关（r = 0.623，<0.01）。鉴于这些发现，本研究认为比较乳脂肪与蛋白质比例可作为奶牛代谢健康的非侵入性指标。牛奶特征与脂解和生酮的血液生化标志物之间的联系表明，这些标志物可用于定期检查奶牛的代谢状态。
