Effects of feeding hay and calf starter as a mixture or as separate components to Holstein calves on intake, growth, and blood metabolite and hormone concentrations

摘要

This study investigated how providing hay mixedwith calf starter to dairy calves affected their solid feedintake, feed sorting, growth, and plasma metabolite andhormone concentrations. Forty Holstein heifer calveswere fed a texturized calf starter (23.4% crude protein,32.3% starch on a dry matter basis) and chopped Kleingrass hay as separate components (CONT) or the samestarter and hay mixed at a 90:10 ratio on an as-fedbasis (MIX) ad libitum from the date transported tothe research farm (4–7 d of life) to 90 d of life. Calveswere provided milk replacer (28% crude protein, 15%fat) at up to 557 g/d before the study, 737 g/d fromd 14 to 20, 1,105 g/d from d 21 to 41, 737 g/d from d42 to 48, and 557 g/d from d 49 to 55 on a dry matterbasis. calves were fully weaned on d 56. Feed sortingfor the MIX calves was evaluated using the Penn StateParticle Separator; the sorting index was calculatedas the actual intake as a percentage of predicted intake,with values >100% indicating sorting for andvalues <100% indicating sorting against. Treatmentdid not affect solid feed intake, growth performance,or plasma metabolite or hormone concentration duringthe preweaning or weaning periods. However, calvesin the MIX treatment had less neutral detergent fiberintake as a percentage of solid feed intake than CONTcalves in the preweaning (23.3 vs. 37.0%) and weaning(23.5 vs. 25.8%) periods, although MIX calves sorted(107.2%) for long particles, which were primarily hay,during weaning. During the postweaning period, MIXcalves had greater neutral detergent fiber intake as apercentage of solid feed intake compared with CONTcalves (23.4 vs. 22.7%), although they sorted againstlong particles (84.4%), and decreased solid feed drymatter intake compared with CONT calves (3,292vs. 3,536 g/d) and average daily gain (1.20 vs. 1.31kg/d). Weaned calves in the MIX treatment also hadlower plasma concentration of glucagon-like peptide 2compared with CONT (0.46 vs. 0.77 ng/mg) but hadhigher plasma concentrations of ghrelin (0.05 vs. 0.03ng/mg). These results suggest that feeding a mixtureof texturized calf starter and chopped hay at the 90:10ratio to postweaned calves may decrease solid feed intakeand growth.