Deltamethrin Application on Pre-Weaned Calves Improves Feed Consumption, Stress and Fatigue Status under Heat Stress Conditions.

Fly infestation remains a universal problem for dairy cattle herds, affecting the animals' health and welfare status. Pre-weaned dairy calves are significantly challenged by the direct and indirect consequences of severe fly infestation, heat-stress and their interaction, which contribute to a stressful and fatiguing environment. Among several physiological, behavioral, clinical and biochemical traits, serum cortisol (SC) and creatine kinase (CK) levels, as well as feed consumption can be used as valid indicators of potential stressful and fatiguing conditions and, therefore, can be efficiently used for stress analysis studies.

Fly repellency using deltamethrin may reduce intramammary infections of dairy cows under intensive management.

The aim of this study was to assess the possible effect of the fly repellent deltamethrin on the full microbiological profile of the intramammary infections as well as on the somatic cell count in one Greek dairy cattle farm under intensive management, during peak fly season. Fifty five multiparous cows, stabled in the same farm, were randomly divided in three groups; cows of Group A were dressed on their back with deltamethrin, cows of Group B remained untreated within the same pen and cows of Group C remained untreated in a separate pen. Clinical records of the herd showed a history of clinical and subclinical mastitis (especially during spring and early summer) and fly infestation.