RESUMEN
A total of 318 cows were monitored in the pre-breeding postpartum period for the presence of three production stressors: lameness, subclinical mastitis and body condition score (BCS) loss. For each stressor, cows were given a classification of severely, moderately or non-affected based on mobility scores, somatic cell counts and BCS change. The number of days from calving to onset of the first luteal phase was greater in cows that had one severe production stressor (median 44 days) or two moderate production stressors (41 days) compared with cows that had no stressors (31 days) (P=0.02 and P=0.04, respectively). More than one severe stressor increased the interval further. There was no difference between cows with one moderate stressor (median 38 days) and those with none (P=0.13). The delay to the first luteal phase was significantly longer in cows with two moderate stressors if the onset of one stressor occurred at the time when resumption of ovarian activity was expected. The presence of these production stressors in early lactation had no effect on the interval from calving to establishment of the next pregnancy or the number of inseminations required despite the negative effect on the onset of the luteal phase.
