Milk yield residuals and their link with the metabolic status of dairy cows in the transition period

Abstract

The transition period is one of the most challenging periods in the lactation cycle of high-yielding dairy cows. It is commonly known to be associated with diminished animal welfare and economic performance of dairy farms. The development of data-driven health monitoring tools based on on-farm available milk yield dev has shown potential in identifying health-perturbing events. As proof of principle, we explored the association of these milk yield residuals with the metabolic status of cows during the transition period. Over 2 years, 117 transition periods from 99 multiparous Holstein Friesian cows were monitored intensively. Pre- and postpartum dry matter intake was measured and blood samples were taken at regular intervals to determine BHB, NEFA, insulin, glucose, fructosamine and IGF1 concentrations. The expected milk yield in the current transition period was predicted with 2 previously developed models ( nextMILK and SLMYP ) using low-frequency test day ( TD ) data and high-frequency milk meter ( MM ) data from the animal's previous lactation, respectively. The expected milk yield was subtracted from the actual production to calculate the milk yield residuals in the transition period ( MRT ) for both TD and MM data, yielding MRT TD and MRT MM . When the MRT is negative, the realized milk yield is lower than the predicted milk yield, in contrast, when positive, the realized milk yield exceeded the predicted milk yield. First, blood plasma analytes, dry matter intake and MRT were compared between clinically diseased and non-clinically diseased transitions. MRT TD and MRT MM , postpartum dry matter intake and IGF1 were significantly lower for clinically diseased versus non-clinically diseased transitions, whereas BHB and NEFA concentrations were significantly higher. Next, linear models were used to link the MRT TD and MRT MM of the non-clinically diseased cows with the dry matter intake measurements and blood plasma analytes. After variable selection, a final model was constructed for MRT TD and MRT MM , resulting in an adjusted R 2 of 0.47 and 0.73, respectively. While both final models were not identical the retained variables were similar and yielded comparable importance and direction. In summary, the most informative variables in these linear models were the dry matter intake postpartum and the lactation number. Moreover in both models, lower and thus also more negative MRT were linked with lower dry matter intake and increasing lactation number. In the case of an increasing dry matter intake, MRT TD was positively associated with NEFA concentrations. Furthermore, IGF1, glucose and insulin explained a significant part of the MRT. Results of the present study suggest that milk yield residuals at the start of a new lactation are indicative of the health and metabolic status of transitioning dairy cows in support of the development of a health monitoring tool. Future field studies including a higher number of cows from multiple herds are needed to validate these findings.

Topics & Concepts