Bovine respiratory syncytial virus reinfections and decreased milk yield in dairy cattle

Summary

The influence of Bovine Respiratory Syncytial Virus (BRSV) reinfections on the daily milk yield was studied by evaluating the milk production of 32 BRSV reinfected cows. For the estimation of milk production losses, four lactation curve models were used, including a gamma function, a second degree polynomial, and both of these models with a lag variable. Bovine respiratory syncytial virus reinfections seemed to have only a small effect on the daily milk production. Comparison of the true production with an estimated production according to the gamma function showed that the production for first lactation cows dropped 0.14 kg on average and for cows in their second or later lactation 0.56 kg on average, during 5 consecutive days in the infection period. For the second‐degree polynomial model these values were respectively 0.42 kg and 0.80 kg. All calculated average production losses were relatively small and not significant (P>0.15). The models without lag variable were more suitable than the models with the lag variable to estimate small production losses caused by BRSV reinfections. The power of this study was sufficient to detect a decrease in production of approximately 1 ‐ 1.5 kg milk per cow per day. It was therefore concluded that BRSV reinfections were not associated with an important loss of milkproduction.

Notes

Department of Herd Health and Reproduction, Faculty of Veterinary Medicine, Utrecht University, Yalelaan 7, 3584 CL Utrecht, the Netherlands, Tel.**31–30 533836/531248, Telefax ** 31–30521887.

Department of Animal Husbandry, Agricultural University, P.O. Box 338, 6700 AH Wageningen, the Netherlands.

Institute for Animal Science and Health (1D‐DLO), Department of Bovine Virology, P.O. Box 65, 8200 AB Lelystad, the Netherlands.

Corresponding author.

Additional information

Notes on contributors

W.H.M. van der Poel

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