Diarrhea Duration and Performance Outcomes of Pre-Weaned Dairy Calves Supplemented with Bacteriophage

Abstract This study aimed to evaluate lytic bacteriophage supplementation in pre-weaned dairy calves over neonatal calf diarrhea and respiratory diseases occurrence, performance and biochemical parameters. Also, to determine bacterial agents causing NCD. Two hundred Holstein×Gyr crossbred female calves were divided into two groups: Control (CON, n = 100), no supplementation; and Bacteriophage (PHAGE, n = 100) bacteriophage supplementation (1 g/day) from d 3 until d 70 of life. Calves were monitored daily for respiratory disease and diarrhea, as for age at the first diarrheic episode and its duration. Fecal samples were cultured for isolation of Escherichia coli and Salmonella spp. colonies and PCR was performed to identify E. coli virulence genes and to confirm Salmonella spp. Performance outcomes were evaluated up to 80 d of age. Blood samples were collected to determine serum levels of total proteins, albumin, cholesterol, γ-glutamyl transferase and urea. PHAGE group had fewer days in diarrhea and duration of the first episode was lower, compared to CON group. Fecal samples of three animals in PHAGE and nine in CON were positive for E. coli in PCR. Thoracic perimeter tended to be higher in supplemented animals. Average daily gain mean of PHAGE was higher in the first 30 d of life, at the beginning of step-down weaning (up to 42 d) and after weaning (up to 80 d). PHAGE mean was lower for albumin and higher for urea. Therefore, phage therapy during the pre-weaned period reduced the duration of neonatal diarrhea, providing greater weight gain for calves.