Pereira Murillo C S, Yang Wenzhu Z, Beauchemin Karen A, McAllister Tim A, Wood Katharine M, Penner Gregory B
Department of Animal and Poultry Science, University of Saskatchewan, Saskatoon, Canada.
Agriculture and Agri-Food Canada, Lethbridge Research and Development Centre, Lethbridge, Canada.
Transl Anim Sci. 2021 Jan 4;5(1):txaa236. doi: 10.1093/tas/txaa236. eCollection 2021 Jan.
This study was designed to evaluate the effect of silage source (barley vs. wheat silage) when harvested at two chop lengths (low vs. high physically effective neutral detergent fiber []) and when barley silage was partially replaced with straw to increase the undigested neutral detergent fiber () concentration on performance and carcass characteristics of finishing steers. Four hundred and fifty yearling commercial crossbred steers with an initial body weight () of 432 ± 30.5 kg were allocated to 30 pens and fed diets containing 90% concentrate:10% forage for 123 d in a completely randomized block design with a 2 × 2 + 1 factorial arrangement. Treatments included 1) barley silage () with low peNDF (); 2) BarS with high peNDF ); 3) BarS with straw to yield a diet with ; 4) wheat silage () LpeNDF; and 5) . There were no silage × peNDF interactions for dry matter intake (), average daily gain (), or gain to feed ratio (), but cattle fed WhS LpeNDF had a lower ( < 0.01) proportion of yield grade 3 and a greater proportion in yield grade 2 carcasses than cattle fed BarS LpeNDF or HpeNDF and WhS HpeNDF. Cattle fed WhS LpeNDF had greater ( = 0.02) incidence of severe liver abscesses when compared with cattle fed BarS LpeNDF or HpeNDF and WhS HpeNDF. Cattle fed BarS consumed less ( < 0.01) uNDF as a percentage of BW, had increased ( = 0.02) ADG, heavier ( = 0.02) hot carcass weight, with greater ( = 0.01) back fat thickness, and ( < 0.01) incidence of minor liver abscesses when compared with cattle fed WhS. Feeding HpeNDF did not affect DMI, ADG, or G:F, but increased ( = 0.02) marbling score and reduced ( < 0.01) the proportion AA quality grade and increased ( < 0.01) those classified as AAA when compared with cattle fed LpeNDF. Cattle fed low uNDF had lesser ( < 0.01) uNDF intake as a percentage of BW, greater dressing percentage ( = 0.01), had a lower ( < 0.01) proportion of carcasses in yield grade 2, and a greater ( < 0.01) proportion of carcasses in yield grade 3 when compared with cattle fed high uNDF. Thus, silage source, peNDF, and uNDF content do not impact DMI or G:F when diets contain 10% forage, but BarS relative to WhS as well strategies increasing the peNDF concentration may increase ADG, HCW, back fat thickness, dressing percentage, marbling score, and carcasses classified as quality grade AAA. Future research is needed to evaluate the usefulness of peNDF and uNDF in rations for finishing cattle.
本研究旨在评估青贮饲料来源（大麦青贮与小麦青贮）、两种切碎长度（低物理有效中性洗涤纤维[peNDF]与高peNDF）以及当大麦青贮被部分秸秆替代以提高未消化中性洗涤纤维（uNDF）浓度时，对育肥牛生长性能和胴体特性的影响。450头初始体重（BW）为432±30.5千克的一岁商用杂交育肥牛被分配到30个栏中，按照2×2 + 1析因设计的完全随机区组设计，饲喂含90%精料：10%粗饲料的日粮，为期123天。处理包括：1）低peNDF的大麦青贮（BarS）；2）高peNDF的BarS；3）添加秸秆的BarS以获得含特定uNDF的日粮；4）低peNDF的小麦青贮（WhS）；5）……干物质采食量（DMI）、平均日增重（ADG）或增重耗料比（G:F）不存在青贮饲料×peNDF的交互作用，但与饲喂低peNDF或高peNDF的BarS以及高peNDF的WhS的牛相比，饲喂低peNDF的WhS的牛3级产肉等级的比例更低（P<0.01），2级胴体的比例更高。与饲喂低peNDF或高peNDF的BarS以及高peNDF的WhS的牛相比，饲喂低peNDF的WhS的牛严重肝脓肿的发生率更高（P = 0.02）。与饲喂WhS的牛相比，饲喂BarS的牛每千克体重摄入的uNDF占比更低（P<0.01），ADG更高（P = 0.02），热胴体重更重（P = 0.02），背膘厚度更厚（P = 0.01），小肝脓肿的发生率更高（P<0.01）。饲喂高peNDF对DMI、ADG或G:F没有影响，但与饲喂低peNDF的牛相比，大理石花纹评分更高（P = 0.02），AA级质量等级的比例降低（P<0.01），AAA级的比例增加（P<0.01）。与饲喂高uNDF含量日粮的牛相比，饲喂低uNDF含量日粮的牛每千克体重的uNDF摄入量占比更低（P<0.01），屠宰率更高（P = 0.01）；2级产肉等级胴体的比例更低（P<0.01）；3级产肉等级胴体的比例更高（P<0.01）。因此，当日粮中粗饲料含量为10%时，青贮饲料来源、peNDF和uNDF含量不会影响DMI或G:F，但相对于WhS而言BarS以及提高peNDF浓度的策略可能会增加ADG、热胴体重、背膘厚度、屠宰率、大理石花纹评分以及被归类为AAA级质量等级的胴体比例。未来需要开展研究以评估peNDF和uNDF在育肥牛日粮中的实用性。
