Fig. 1

Histological scores and light micrographs of hematoxylin and eosin stained jejunal and ileal sections of calves feeding on different sources of milk. a Jejunal histological scores. b Representative photomicrographs of hematoxylin and eosin stained jejunal sections in the BTM, UWM, PWM, and AWM groups (H & E 20× and 60× original magnification). c Ileal histological scores. d Representative photomicrographs of hematoxylin and eosin stained ileal sections in the BTM, UWM, PWM, and AWM groups (H & E 10× and 60× original magnification). Intestine pictures from calves receiving bunk tank milk, untreated waste milk, pasteurized waste milk, or acidified waste milk after feeding on colostrum, respectively. The jejunal and ileal basal structure of the calves in the four treatments was clear and intact. Slight epithelial lesions (arrows) were observed in the jejunum and ileum of the BTM and UWM fed calves, and leukocyte infiltration (arrows) was found in the UWM and AWM fed calves