PSXII-20 Whole flint corn grain or tropical grass hay free choice in the diet of milk-fed dairy calves

Abstract

Abstract The objective of this study was to evaluate the effect of whole flint corn grain or tropical grass hay free choice, as a fiber source in the diet, on the performance, ruminal and intestinal development of Holstein dairy calves. Forty-two Holstein calves were used in a randomized block design, considering sex, birth date and weight at 21 days of age (48.7 ± 0.82 kg), when the study started. Three solid diets were compared: 1) SC: starter concentrate only (24% CP, 14% NDF, 47% NFC); 2) SCH: starter concentrate, with free access to chopped Tifton-85 hay; and 3) SCW: starter concentrate with free access to whole flint corn grain. Animals were fed with 6 L/d until d 21, and then 4L/d of whole milk until gradual weaning at d 56. At weaning, 12 animals were randomly selected to be slaughtered to evaluate the weight of forestomach compartments and rumen and intestine morphometrics. Data were analyzed using the GLM or MIXED (repeated measures) procedure of SAS, and the means were compared using Tukey test (P ≤ 0.05). The SCH diet increased the total DMI (P = 0.01) and ADG (P = 0.01). Calves fed with SCH diet presented higher total proximal digestive tract weight (kg; P < 0.01). The empty reticulum-rumen weight was higher in calves fed the SCH diet (P = 0.03). The papillae area was higher in calves fed with SCH diet (P = 0.05). The depth of the crypts and the number of goblet cells from the duodenum and cecum were not affected by diets; however, the duodenum villus height was higher for animals that received SCH (P = 0.02). The tropical grass hay supplementation in the diet improved performance, ruminal and intestinal development. The whole flint corn grain do not play a fiber role for dairy calves.