Effect of starter form, starch concentration, and amount of forage fed on Holstein calf growth from 2 to 4 months of age

摘要

Young, weaned calves are commonly offered ad libitumforage with limited amounts of starter, in contrastto the suggested amount of approximately 5% foragein the diet due to the limited capacity of the rumen,as well as limited ability to digest high fiber feeds. Theobjective of this research was to compare 2 types ofstarters (low starch, pelleted vs. high starch, textured),both fed either ad libitum with 5% chopped hay, or fedat restricted rates with ad libitum long grass hay tocalves between 2 and 4 mo of age. In trial 1, 48 calveswere housed in group pens (68.4 ± 3.37 kg of initialbody weight ± standard deviation; 3 pens of 4 calves/pen) and randomly assigned to 1 of 4 diets: (1) lowstarch pelleted starter (8% starch) blended with 5%chopped hay fed free choice; (2) high starch texturedstarter (45% starch) blended with 5% chopped hay fedfree choice; (3) low starch pelleted starter (8% starch)fed at a rate up to 2.3 kg of dry matter (DM)/d, withfree-choice long grass hay; or (4) high starch texturedstarter (45% starch) fed at a rate up to 2.3 kg of DM/d,with free-choice long grass hay. Trial 1 was analyzed asa completely randomized design using a 2 × 2 arrangementof treatments. Repeated measures were used asappropriate. Pen was the experimental unit. In trial 2,48 calves (76.4 ± 1.55 kg of initial body weight; 6 pensof 4 calves/pen) were randomly assigned to 1 of 2 diets:(1) ad libitum access to a blend of 95% high starchtextured starter (42% starch) and 5% chopped grasshay; or (2) high starch textured starter fed up to 2.7 kgof DM/d with free-choice long grass hay. Trial 2 wasanalyzed as for trial 1, without factorial arrangement.Trials were 56 d long. In trial 1, feed efficiency, averagedaily gain (ADG), and change in hip width weregreater for calves fed high versus low starch diet. Finalhip width, ADG, DM intake, and change in hip widthwere greater for calves fed limited chopped versus freechoicelong hay diets. In trial 2, intake, feed efficiency,and all growth measurements were greater in calves fedthe ad libitum mixed diet compared with those limitfedstarter up to 2.7 kg as fed with ad libitum hay. Adlibitum hay intake was highly variable among pens anddiffered up to 2.5-fold by the last week of the trials. Inboth trials, restricted feeding of starter with ad libitumlong grass hay reduced total DM intake by 13 to 17%,ADG by 20%, and hip width change by 10 to 23%compared with a blend of 95% starter and 5% choppedgrass hay fed ad libitum.