Reciprocal combinations of alfalfa hay and corn silage in the starter diets of Holstein dairy calves: Effects on feed sorting, meal pattern, and ingestive behavior

We investigated the effects of replacing alfalfa hay (AH) with corn silage (CS) in the starter diet on feed intake, feeding and chewing behavior, and sorting activity using 30 newborn male Holstein calves which were assigned randomly to 3 groups receiving starter diets containing chopped AH [100.00 g/kg on dry matter (DM) basis; AH), CS (100.00 g/kg; CS), or their equal combination (AHCS). The starter diets had the same nutrient composition but differed in DM content (P = 0.001) and thereby, particle size distribution. Feeding AHCS or CS tended to increase day time meal duration (pre-weaning; P = 0.09) and meal frequency (post-weaning; P = 0.08) and tended (P = 0.08) to decrease inter-meal interval (post-weaning), and thereby, tended to increase (P = 0.09) and increased (P = 0.04) day time eating time during the pre- and post-weaning periods, respectively, without affecting nutrient intake or body weight. Calves fed AHCS or CS had lower eating rate during the pre-weaning period (P = 0.03). Concurrent increase in day time rumination frequency (P = 0.04) and duration (P = 0.04) together with a decrease in rumination bout interval (P = 0.03) in calves fed AHCS or CS increased ruminating time (P = 0.001) during the post-weaning period. Time devoted to standing and lying decreased (P = 0.002) and tended (P = 0.06) to decrease, respectively, as the amount of CS increased in the starter diets during the post-weaning period. Calves fed AH or AHCS sorted for the particles retained on second (P = 0.001) and third (P = 0.001) sieves of the Penn State Particle Separator (PSPS) and against the feed materials retained on the bottom pan (P = 0.001); however, calves fed CS sorted against the particles retained on second sieve of the PSPS and for the particles retained on third sieve of the PSPS and feed materials retained on the bottom pan. Crude protein and neutral detergent fiber intakes of particles retained on the both 8.00- and 1.18-mm sieves increased and tended to increase, respectively, in calves fed AHCS or CS compared with calves fed AH. Blood concentration of albumin was higher in calves fed AHCS compared with calves fed AH or CS during the pre-weaning period (P = 0.001). Overall, replacing AH with CS increased day time eating time by increasing meal frequency and duration or decreasing inter-meal interval but did not influence feed intake due to lower eating rate. Finally, calves exhibited feed sorting at the extent to which they balanced intake of nutrients and met their nutritional needs.