Increased super-conditioning temperature of corn grain affects performance, skeletal growth, and blood metabolites in Holstein dairy calves

摘要

We aimed to evaluate the effects of feeding superconditionedcorn at different temperatures on intake,growth performance, total-tract starch digestibility,rumen fermentation, blood metabolites, and feedingbehavior of dairy calves. Thirty-six Holstein femaledairy calves (40 ± 1.72 kg of body weight, ± SD) wererandomly assigned to 1 of the following 3 treatments:(1) ground corn (control; CON; n = 12), (2) cornsuper-conditioned at 75°C (T-75; n = 12), and (3) cornsuper-conditioned at 95°C (T-95; n = 12). Three mashstarter feeds with an identical nutritional compositionwere blended with 5% chopped alfalfa hay and fed toindividually-housed calves from d 3 to 77 of their birth.All calves were fed 4 L/d of pasteurized whole milktwice daily since d 3 to 56, followed by 2 L/d of morningfeeding from d 57 to 63 of age. Calves were weanedon d 63 and remained in the study until d 77. The T-75and T-95 diets increased total-tract starch digestibilitycompared with the CON diet. Dry matter intake andweaning or final BW were not affected by treatments;however, average daily gain and feed efficiency increasedin calves fed T-95 in the overall period. The T-95 dietincreased withers height and tended to increase hipheight compared with other diets, but feeding behaviordid not change throughout the experimental period.Ruminal Ph decreased in calves fed the T-95 dietcompared with T-75 and CON diets. The molar proportionof ruminal propionate increased, whereas theacetate-to-propionate ratio tended to decrease in calvesfed the T-95 compared with CON diet. Calves fed theT-95 diet had the highest blood glucose concentration,whereas a trend for increased insulin concentration wasobserved in calves fed T-95 compared with other diets.In conclusion, super-conditioning temperature of corn(T-95 vs. T-75 and CON) improved the average dailygain, feed efficiency, and skeletal growth, but did notinfluence dry matter intake during the first 77 d of age.Finally, the total-tract starch digestibility increased,whereas ruminal Ph dropped during the postweaningperiod as super-conditioning temperature elevated.