Can the milk metabolome be used to predict the health of dairy cows in relation to tail tip lesions?

Current studies are investigating the suitability of examining the tail tip for specific lesions to assess the metabolic health of animals. Lesions on the tail tip of dairy cows may be caused by circulatory disturbances as a result of systemic inflammatory processes. Metabolomic approaches are used to detect and quantify pro-inflammatory metabolite profiles in biological samples to better understand metabolic inflammation in humans and animals. In dairy cows, changes in plasma and milk metabolite profiles have been associated with ketosis, heat stress and mastitis. Systemic inflammatory conditions have been described in dairy cows with increased metabolic load, particularly in the liver, especially during calving and early lactation. To further investigate the potential relationship between these tail tip lesions and metabolic health, milk samples were collected during the early stages of lactation. The tail tip of 51 dairy cows were examined on a weekly basis for the presence of lesions during the entire lactation period. In addition, milk samples were collected on the 14th day of lactation (+/- 1 day) to test the hypothesis that milk  metabolites can be used as indicators of systemic inflammation. Milk metabolite profiling was performed using MxP Quant 500 kit (Biocrates, Innsbruck). The results of this study indicated that 56.9 % of the cows exhibited a bleeding lesion at the tail tip during the study period. In 31.4 % of the cows, a loss of a tail part due to auto-amputation was recorded. A comparison was made of cows with bleeding lesions between day 14 a.p. and 80 p.p. with cows without such lesions. Metabolite profiles in milk differ only in the concentration of sarcosine (p<0.0108) with higher values in cows with bleeding lesions. In other studies, an increase in sarcosine levels in the plasma of cows was detected following a LPS challenge. Although single metabolites appear to be associated with tail tip lesions, the milk metabolome determined by MxP Quant 500 kit is not useful to predict metabolic health in association with tail tip lesions.