ABSTRACT: Introducing forage in the young calfdiet during the milk-feeding period stimulates rumendevelopment. It was hypothesized that performancein dairy calves would depend on forage provisionand starter physical form such that the textured starter(TS) feed with corn silage (CS) supplementationwould benefit calf performance. This study evaluatesthe effects of the physical form of starter diets and CSsupplementation on performance, rumen fermentationcharacteristics, and structural growth of dairy calves.Forty-eight 3-d-old Holstein dairy calves with a meanstarting BW of 42.1 kg (SD 2.4) were used in a 2 × 2factorial arrangement with the factors dietary CS level(0 or 15% on DM basis) and physical form of starter(mashed vs. textured). Individually housed calveswere randomly assigned (n = 12 calves per treatment:6 males and 6 females) to 4 treatments: 1) a mashedstarter (MS) feed with no CS (MS-NCS), 2) a MS feedwith CS (MS-CS), 3) a TS feed with no CS (TS-NCS),and 4) a TS feed with CS (TS-CS). The calves had adlibitum access to water and starter throughout the study.All calves were weaned on d 56 of age and remainedin the study until d 66. The interaction of the physicalform of the starter and CS provision was significant(P < 0.01) for the starter intake, with the greatestintake for TS-CS treatment during the preweaningand overall periods. Regardless of the physical formof starter, starter intake, ADG, weaning BW, final BW,ruminal pH, the molar proportion of acetate, and theacetate-to-propionate ratio were greater (P < 0.01) forCS-supplemented calves compared with unsupplementedcalves. No interaction (P > 0.05) was detectedbetween the physical form of starter and CS provisionwith respect to the rumen fermentation parameters andbody measurements. Total rumen VFA concentrationand the molar proportion of propionate were greater(P < 0.01) in calves fed TS compared with MS-fedcalves. In conclusion, independent of the physical formof starter, inclusion of 15% CS in starte
