Enemark J M D, Jørgensen R J, Kristensen N B
Cattle Production Medicine Research Group, Department of Clinical Studies, Large Animal Medicine, Royal Veterinary and Agricultural University, Dyrlaegevej 88, DK-1870 Frederiksberg C, Denmark
Vet Res Commun. 2004 Nov;28(8):687-709. doi: 10.1023/b:verc.0000045949.31499.20.
An observational study was conducted in six Danish dairy herds. A specially designed stomach tube was compared to the rumenocentesis technique as part of the monitoring of rumen pH. In contrast to a previous study, the use of the stomach tube appeared to reduce saliva contamination. However, correlation with the rumenocentesis technique was poor ( r = 0.33; p = 0.019) and a linear model could only partly explain variations between either results. The presence of subclinical rumen acidosis (SRA) was evidenced in one herd only, as judged by results obtained by the rumenocentesis technique. The present study revealed some limitations of the rumenocentesis technique in small or medium-sized herds due to difficulties in selecting sufficient numbers of cows in the respective groups at risk. The finding of two apparently clinical normal cows with rumen pH values below 5.0 leads to the consideration that such fluctuations may be temporary and at least does not give rise to clinical symptoms. However, the long-term effect of such fluctuations is not known. In general, primiparous cows seemed more prone to low ruminal pH values (< 6.0), higher ruminal concentrations of short-chain fatty acids, and possibly to metabolic acidosis, than were multiparous cows. Ruminal propionate was the most precise predictor of rumen pH, whereas milk fat percentage varied greatly between lactational groups. Blood lactate dehydrogenase (LDH), beta-hydroxybutyrate (BHB) and fructosamine as well as urine phosphorus excretion and renal net acid-base excretion (NABE) were related to ruminal acid load, but were not predictive of rumen pH. Monitoring of dairy herds for SRA should be performed routinely and employ several diagnostic tools (rumenocentesis, renal NABE determination) as well as specific knowledge of herd management and feeding routines.
在丹麦的六个奶牛场进行了一项观察性研究。作为瘤胃pH值监测的一部分，将一种专门设计的胃管与瘤胃穿刺技术进行了比较。与之前的一项研究不同，使用胃管似乎减少了唾液污染。然而，与瘤胃穿刺技术的相关性较差（r = 0.33；p = 0.019），线性模型只能部分解释两种结果之间的差异。根据瘤胃穿刺技术获得的结果判断，仅在一个牛群中发现了亚临床瘤胃酸中毒（SRA）。本研究揭示了瘤胃穿刺技术在中小型牛群中的一些局限性，因为在各个风险组中难以选择足够数量的奶牛。发现两头临床症状明显正常但瘤胃pH值低于5.0的奶牛，这使得人们认为这种波动可能是暂时的，至少不会引起临床症状。然而，这种波动的长期影响尚不清楚。一般来说，初产奶牛似乎比经产奶牛更容易出现低瘤胃pH值（< 6.0）、瘤胃中较高的短链脂肪酸浓度，并且可能更容易出现代谢性酸中毒。瘤胃丙酸是瘤胃pH值最精确的预测指标，而乳脂肪率在泌乳组之间差异很大。血乳酸脱氢酶（LDH）、β-羟丁酸（BHB）、果糖胺以及尿磷排泄和肾脏净酸碱排泄（NABE）与瘤胃酸负荷有关，但不能预测瘤胃pH值。对奶牛场进行SRA监测应常规进行，并采用多种诊断工具（瘤胃穿刺、肾脏NABE测定）以及牛群管理和饲养程序的专业知识。
