Thomson D J, Waldo D R, Goering H K, Tyrrell H F
Ruminant Nutr. Lab., U.S. Department of Agriculture, Beltsville, MD 20705.
J Anim Sci. 1991 Nov;69(11):4644-59. doi: 10.2527/1991.69114644x.
Alfalfa and orchardgrass herbages of similar digestibility were harvested at early and late maturity from primary growth and conserved as direct-cut silage using formic acid and formaldehyde simultaneously. Major compositional differences between the silages were lower NDF (principally hemicellulose) and a greater N content in alfalfa than in orchardgrass. An initial group of eight steers was slaughtered with a mean BW of 222 kg, and each of the four silages was fed to comparable groups of eight Holstein steers. Ad libitum DMI per unit of metabolic BW for alfalfa silages was 128% of that for orchardgrass silages. The ADG of steers fed alfalfa silages was 132% of that of steers fed orchardgrass silages. Despite greater ad libitum intake, total gut fill, as a percentage of BW, on alfalfa silages was 77% of that on orchardgrass silages. Daily empty BW gain of steers fed alfalfa silages was 158% of that of steers fed orchardgrass silages. Daily energy retention of steers fed alfalfa silages was 180% of that of steers fed orchardgrass silages. Steers fed alfalfa silages retained 140% more protein than steers fed orchardgrass silages did, but steers fed alfalfa silages retained only 71% as much protein energy relative to their total energy retention compared with steers fed orchardgrass silages. Differences in composition of daily energy retained were almost totally a result of differences in the total daily energy retention. Late alfalfa silage produced a greater daily gain than orchardgrass silage cut 2 wk earlier because greater intake compensated for lower digestibility.
在初花期和盛花期从一次生长中收获了消化率相似的苜蓿和鸭茅牧草，并同时使用甲酸和甲醛将其制成直接切割青贮饲料。青贮饲料之间的主要成分差异在于，苜蓿中的中性洗涤纤维（主要是半纤维素）含量较低，氮含量高于鸭茅。最初的一组八头阉牛被屠宰，平均体重为222千克，四种青贮饲料中的每一种都喂给了八头体重相当的荷斯坦阉牛。每单位代谢体重的苜蓿青贮饲料随意采食量是鸭茅青贮饲料的128%。饲喂苜蓿青贮饲料的阉牛的平均日增重是饲喂鸭茅青贮饲料的阉牛的132%。尽管随意采食量更大，但以体重百分比计算，苜蓿青贮饲料的总肠道充盈度是鸭茅青贮饲料的77%。饲喂苜蓿青贮饲料的阉牛的每日空腹体重增加量是饲喂鸭茅青贮饲料的阉牛的158%。饲喂苜蓿青贮饲料的阉牛的每日能量保留量是饲喂鸭茅青贮饲料的阉牛的180%。饲喂苜蓿青贮饲料的阉牛比饲喂鸭茅青贮饲料的阉牛多保留140%的蛋白质，但与饲喂鸭茅青贮饲料的阉牛相比，饲喂苜蓿青贮饲料的阉牛相对于其总能量保留量仅保留了71%的蛋白质能量。每日保留能量组成的差异几乎完全是由于每日总能量保留量的差异。晚收的苜蓿青贮饲料比提前两周收割的鸭茅青贮饲料产生的日增重更大，因为更大的采食量弥补了较低的消化率。
