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چکیده
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The objective of this study was to investigate theeffects of grain sources and forage provision on growthperformance, blood metabolites, and feeding behaviorsof dairy calves. Sixty 3-d-old Holstein dairy calves (42.2± 2.5 kg of body weight) were used in a 2 × 3 factorialarrangement with the factors being grain sources (barleyand corn) and forage provision (no forage, alfalfahay, and corn silage). Individually housed calves wererandomly assigned (n = 10 calves per treatment: 5 malesand 5 females) to 6 treatments: (1) barley grain (BG)without forage supplement, (2) BG with alfalfa hay(AH) supplementation, (3) BG with corn silage (CS)supplementation, (4) corn grain (CG) without foragesupplement, (5) CG with AH supplementation, and (6)CG with CS supplementation. All calves had ad libitumaccess to water and starter feed throughout the experiment.All calves were weaned on d 49 and remained inthe study until d 63. Starter feed intake and averagedaily gain (ADG) was greater for calves fed barley thanthose fed corn during the preweaning and overall periods.Calves supplemented with CS had greater finalbody weight and postweaning as well as overall starterfeed intake than AH and non-forage-supplementedcalves. During the preweaning and overall periods,feeding of CS was found to increase ADG comparedwith feeding AH and nonforage diets. However, feed efficiencywas not affected by dietary treatments. Calvessupplemented with CS spent more time ruminatingcompared with AH and control groups; nonnutritive oralbehaviors were the greatest in non-forage-supplementedcalves. Regardless of the grain sources, the rumen pHvalue was greater for AH calves compared with CS andnon-forage-supplemented calves. Blood concentrationof BHB was greater for CS-supplemented calves comparedwith AH and non-forage-supplemented calves.Furthermore, body length and heart girth were greaterfor calves fed barley compared with those fed corn, andalso in forage-supplemented calves compared with nonforage-supplement
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