The influence of calfhood diarrhea and pneumonia on preweaning growth and reproductive performance of Holstein heifers

Aim of the study: To determine the effect of diarrhea and pneumonia on preweaning weight gain and subsequent reproductive performance of Holstein heifers in a hot environment. Study site: Hot-arid zone of northern Mexico (25 °N). Material and methods: This study enrolled 7,809 calves from a single large commercial dairy herd. Calves´ birth and weaning weights were recorded, and subsequent reproductive performance was registered. Main results: The preweaning daily gain in calves suffering diarrhea (573 ± 12 g/d), pneumonia (557 ± 12 g/d), and comorbidity of these diseases (520 ± 13 g/d) were lower (p<0.05) than healthy calves (594 ± 11 g/d). Heifers without diarrhea and pneumonia during the preweaning period conceived 25 days earlier (p<0.05) than herdmates suffering diarrhea comorbid with pneumonia and required 0.4 less (p<0.05) inseminations per pregnancy. The pregnancy rate for healthy heifers during the preweaning period was higher (93.6%; p<0.05) than those of their herdmates who experienced diarrhea (89.2%), pneumonia (89.8%), or both diseases (87.2%). Calves weighing ≤ 36 kg at birth were more susceptible (p<0.05) to diarrhea (incidence 13.3%) than calves ≥ 40 kg (incidence 11.6%). Research highlights: These results highlight the substantial negative influence of diarrhea and pneumonia on preweaning weight gain and subsequent reproductive performance. Also, it was demonstrated that diarrhea is linked to low body weight at calving.