Young, weaned calves are commonly offered ad libitum forage with limited amounts of starter, in contrast to the suggested amount of approximately 5% forage in the diet due to the limited capacity of the rumen, as well as limited ability to digest high fiber feeds. The objective of this research was to compare 2 types of starters (low starch, pelleted vs. high starch, textured), both fed either ad libitum with 5% chopped hay, or fed at restricted rates with ad libitum long grass hay to calves between 2 and 4 mo of age. In trial 1, 48 calves were housed in group pens (68.4 ± 3.37 kg of initial body weight ± standard deviation; 3 pens of 4 calves/pen) and randomly assigned to 1 of 4 diets: (1) low starch pelleted starter (8% starch) blended with 5% chopped hay fed free choice; (2) high starch textured starter (45% starch) blended with 5% chopped hay fed free choice; (3) low starch pelleted starter (8% starch) fed at a rate up to 2.3 kg of dry matter (DM)/d, with free-choice long grass hay; or (4) high starch textured starter (45% starch) fed at a rate up to 2.3 kg of DM/d, with free-choice long grass hay. Trial 1 was analyzed as a completely randomized design using a 2 × 2 arrangement of treatments. Repeated measures were used as appropriate. Pen was the experimental unit. In trial 2, 48 calves (76.4 ± 1.55 kg of initial body weight; 6 pens of 4 calves/pen) were randomly assigned to 1 of 2 diets: (1) ad libitum access to a blend of 95% high starch textured starter (42% starch) and 5% chopped grass hay; or (2) high starch textured starter fed up to 2.7 kg of DM/d with free-choice long grass hay. Trial 2 was analyzed as for trial 1, without factorial arrangement. Trials were 56 d long. In trial 1, feed efficiency, average daily gain (ADG), and change in hip width were greater for calves fed high versus low starch diet. Final hip width, ADG, DM intake, and change in hip width were greater for calves fed limited chopped versus free-choice long hay diets. In trial 2, intake, feed efficiency, and all growth measurements were greater in calves fed the ad libitum mixed diet compared with those limit-fed starter up to 2.7 kg as fed with ad libitum hay. Ad libitum hay intake was highly variable among pens and differed up to 2.5-fold by the last week of the trials. In both trials, restricted feeding of starter with ad libitum long 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% chopped grass hay fed ad libitum.

中文翻译：

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发酵剂形式，淀粉浓度和饲喂草料量对2至4个月大的荷斯坦犊牛生长的影响。

通常建议给幼小的断奶犊牛以有限量的起子随意采食，因为瘤胃容量有限以及消化高纤维饲料的能力有限，建议的日粮中约有5％的牧草。这项研究的目的是比较两种类型的发酵剂（低淀粉，造粒与高淀粉，有组织的），既可以随意饲喂5％的切碎的干草，也可以以有限的速率随意饲喂长草干草到犊牛之间。 2和4月龄。在试验1中，将48只犊牛放在组围栏中（68.4±3.37 kg的初始体重±标准差; 3支围栏，每只围栏4头围栏），并随机分配给4种日粮中的1种：（1）低淀粉粒状起子（8 ％淀粉）与5％切碎的干草混合自由选择；（2）高淀粉质感发酵剂（45％淀粉）与5％切碎的干草混合自由选择；（3）以最高2.3千克干物质（DM）/ d的速率饲喂低淀粉粒状发酵剂（8％淀粉），并带有自由选择的长草干草；或（4）高淀粉质地的发酵剂（45％淀粉）以不超过2.3千克DM / d的速度喂食，并带有自由选择的长草干草。使用2×2治疗安排将试验1分析为完全随机设计。适当地使用重复的措施。笔是实验单位。在试验2中，将48头犊牛（初始体重为76.4±1.55千克； 6笔，每头犊牛4头）分配给2种饮食中的1种：（1）自由获取95％高淀粉质发酵剂的混合物（ 42％的淀粉）和5％的碎干草；或（2）高淀粉质地的起子以自由选择的长草干草喂食高达2.7千克的DM / d。对试验2的分析与对试验1的分析一样，没有进行析因安排。试验时间为56天。在试验1中，饲喂高淀粉和低淀粉饲料的小牛的饲料效率，平均日增重（ADG）和臀部宽度的变化更大。饲喂有限切碎的犊牛与自由选择的长干草饮食相比，最终的臀部宽度，ADG，DM摄入量和臀部宽度变化更大。在试验2中，饲喂自由混合饲料的小牛的进食量，饲料效率和所有生长指标均高于自由饲喂干草的2.7 kg限饲饲喂的小牛。随意采食干草的钢笔之间存在很大差异，到试验的最后一周差异最大为2.5倍。在这两个试验中，限制饲喂的随意食用长草干草的发酵剂会使DM的总摄入量减少13％至17％，ADG减少20％，