Metabolic and productive response and grazing behaviour of lactating dairy cows supplemented with high moisture maize or cracked wheat grazing at two herbage allowance in spring

The aim was to determine the effect of the HA and supplement type (ST) on dry matter intake, milk production and composition, grazing behaviour, rumen function and blood metabolites of grazing dairy cows in the spring season. Experiment I: 64 Holstein Friesian dairy cows were distributed in a factorial design that tested two levels of daily HA (20 and 30 kg DM/cow.day) and two ST (high moisture maize [HMM] and cracked wheat [CW]) distributed in two daily rations (3.5 kg DM/cow/day). Experiment II: four mid-lactation rumen cannulated cows, supplemented with either HMM or CW and managed with the two HA, were distributed in a Latin Square design of 4 x 4, for four 14-d periods to assess ruminal fermentation parameters.

本研究旨在明确春季放牧条件下，牧草供给量（herbage allowance, HA）与补充饲料类型（supplement type, ST）对放牧奶牛的干物质（dry matter, DM）采食量、牛奶产量与乳成分、放牧行为、瘤胃功能及血液代谢物的影响。实验一：选取64头荷斯坦-弗里生奶牛，采用析因设计（factorial design），设置两个每日牧草供给量水平（20与30 kg DM/头·日）、两种补充饲料类型（高水分玉米[high moisture maize, HMM]与碎小麦[cracked wheat, CW]），并统一设置每日补充日粮为3.5 kg DM/头·日。实验二：选取4头泌乳中期瘤胃瘘管奶牛，分别饲喂HMM或CW两种补充饲料，并配合前述两种牧草供给量水平，采用4×4拉丁方设计（Latin Square design），划分为4个为期14天的试验周期，以评估瘤胃发酵参数。