The physical form of starter (finely ground versus pelleted) and alfalfa hay (chopped versus pelleted) in Holstein dairy calves: Effects on growth performance, feeding behaviour, ruminal fermentation, and urinary purine derivatives

Abstract This study evaluated the effects of the physical form of the starter [finely ground starter (GS) vs. pelleted starter (PS)] and physical form of alfalfa hay [chopped alfalfa hay (CAH) vs. pelleted alfalfa hay (PAH)] on growth performance, digestibility, ruminal fermentation, and urinary purine derivatives. Forty 3-day-old male Holstein calves (average BW of 39.7 kg) were assigned in a completely randomized design with a 2 × 2 factorial arrangement of the treatments as follows: (1) ground starter with chopped alfalfa hay (GS-CAH), (2) ground starter with pelleted alfalfa hay (GS-PAH), (3) pelleted starter with chopped alfalfa hay (PS-CAH), and (4) pelleted starter with pelleted alfalfa hay (PS-PAH). The geometric mean particle size for the experimental starter diets were 0.61, 0.76, 2.17, and 2.31 mm for GS-CAH, GS-PAH, PS-CAH, and PS-PAH, respectively. All calves were weaned on d 53 of age and remained in the study until d 73 of age for the final measurements. Results showed that during the pre-weaning period, calves receiving the PS diets had greater starter intake (479 vs. 322 g/d; P = 0.01) and average daily gain (639 vs. 509 g/d; P