Nichols S W, Froetschel M A, Amos H E, Ely L O
Animal and Dairy Science Department, University of Georgia, Athens 30602, USA.
J Dairy Sci. 1998 Sep;81(9):2383-93. doi: 10.3168/jds.S0022-0302(98)70130-4.
Tropical corn silage was compared with sorghum silage as a basal forage in the diets of high producing dairy cows. Sorghum and tropical corn silages were each included in place of ground corn at incremental concentrations in the experimental diets. Eight separate diets were fed, four diets containing each silage ranging in forage neutral detergent fiber (NDF) from approximately 25 to 31% and ranging in total NDF from approximately 41 to 45%. Diets were arranged in a 2 x 4 factorial design and were fed to lactating cows (n = 24; pretrial mean milk production = 39 kg/d; body weight = 656 kg; and days in milk = 81). As concentrations of dietary NDF increased, intake and milk production decreased linearly. The impact of dietary NDF on intake was greater for diets based on tropical corn silage than for diets based on sorghum silage. Energy intake and milk production were reduced, but cows consumed more fiber when challenged with higher dietary concentrations of fiber. The in vitro rate and extent of digestion of dietary samples were correlated with intake response. The rate of in vitro fiber digestion was slower for samples that contained tropical corn silage than for samples that contained sorghum silage. In vivo digestibility measurements were influenced by intake and dietary composition. Results of this trial indicated that sorghum silage can have equal or slightly greater nutritional value than tropical corn silage when these forages are fed at equal concentrations of dietary fiber.
在高产奶牛日粮中，将热带玉米青贮饲料与高粱青贮饲料作为基础粗饲料进行了比较。在试验日粮中，分别以递增浓度用高粱青贮饲料和热带玉米青贮饲料替代玉米粉。共饲喂8种不同日粮，每种青贮饲料各有4种日粮，其饲草中性洗涤纤维（NDF）含量约为25%至31%，总NDF含量约为41%至45%。日粮采用2×4析因设计，饲喂泌乳奶牛（n = 24；预试验平均产奶量 = 39千克/天；体重 = 656千克；泌乳天数 = 81）。随着日粮NDF浓度的增加，采食量和产奶量呈线性下降。与以高粱青贮饲料为基础的日粮相比，以热带玉米青贮饲料为基础的日粮中，日粮NDF对采食量的影响更大。能量摄入量和产奶量降低，但当日粮纤维浓度较高时，奶牛会摄入更多纤维。日粮样本的体外消化率和消化程度与采食量反应相关。含热带玉米青贮饲料的样本的体外纤维消化率比含高粱青贮饲料的样本慢。体内消化率测量受采食量和日粮组成的影响。该试验结果表明，当以相同膳食纤维浓度饲喂这些粗饲料时，高粱青贮饲料的营养价值可能与热带玉米青贮饲料相当或略高。
