Herd health monitoring in dairy farms - discover metabolic diseases. An overview

The transition period, 3 weeks before and 3 weeks after calving, is inevitably accompanied by a negative energy balance, which sometimes causes metabolic disturbances, such as ketosis. Subclinical ketosis (SCK) is defined as an increase in the beta-hydroxybutyrate (BHB) concentration to >= 1.2 mmol/l in the blood. According to a recent study, a value of >= 0.7 mmol/l of non-esterified fatty acids (NEFA) in the blood indicates the potential development of the poor metabolic adaption syndrome (PMAS). With a herd prevalence of 21 %, and an incidence of approximately 40 % within the first 2 weeks after calving, SCK is a relevant herd health problem. The milk yield decreases in the first 2 weeks postpartum by 3-5.3 kg/d for each ketotic cow, and the total milk reduction through the whole lactation period of 305 days averages 112 kg (SD 89 kg). Although the cow does not display any clinical signs of ketosis at this stage, the risk of developing associated production diseases like retained placenta, metritis, displaced abomasum, lameness and clinical ketosis increases and the expected performance in terms of milk production will decrease. The herd health status deteriorates and the risk for early culling increases. Another impact factor is the financial aspect, which includes costs for early death, reduced milk production, reproduction losses, and associated production diseases. In the literature, the calculated costs per SCK case vary between $ 78 and $ 289. The gold standard diagnostic test for SCK is the photometric measurement of BHB in blood. This method is accurate, but results are delayed due to the required laboratory analysis. There are also some rapid cow-side tests, i. e. urine or milk strip tests available to identify ketotic cows. The common disadvantage of these methods is that they are not suitable for herd health monitoring because of the need to collect samples from each cow manually and the high rates of false negative results. However, Fourier transform infrared spectroscopy is suitable for herd health monitoring. It is already being used for the analysis of milk composition. This inexpensive, rapid and simple technique has a specificity of 83.8 % and a sensitivity of 82.4 %. Therefore, FTIR is an early and easy method for detecting ketotic cows, that could help reduce financial and performance losses associated with ketosis.