摘要
Three experiments evaluated delaying corn silage harvest, silage concentration, and source of supplemental protein on performance and nutrient digestibility in growing and finishing diets. Experiment 1 used 180 crossbred yearling steers (body weight [BW] = 428; SD = 39 kg) to evaluate corn silage dry matter (DM) (37% or 43%) and replacing corn with silage (15% or 45% of diet DM) in finishing diets containing 40% modified distillers grains with solubles. Experiment 2 used 60 crossbred steers (BW = 271; SD = 32 kg) to evaluate corn silage harvest DM (37% or 43%) and response to rumen undegradable protein (RUP) supplementation (0.5%, 1.4%, 2.4%, 3.3%, or 4.2% of diet DM) in silage growing diets. Experiment 3 used 9 crossbred lambs (BW = 30.1; SD = 4.1 kg) to evaluate nutrient digestibility of 37% or 43% DM corn silage in silage growing diets fed ad libitum or restricted to 1.5% of BW. In experiment 1, as corn silage concentration increased from 15% to 45%, average daily gain (ADG) and gain-to-feed ratio (G:F) decreased (P ≤ 0.04). Carcass-adjusted final BW and hot carcass weight (HCW) were lower (P ≤ 0.04) for steers fed 45% corn silage compared to 15% when fed for equal days. As DM of corn silage was increased from 37% to 43%, no differences (P ≥ 0.30) in dry matter intake (DMI), ADG, G:F, or HCW were observed. In experiment 2, as DM of corn silage increased from 37% to 43%, ADG and G:F decreased (P ≤ 0.04). Increasing supplemental RUP in the diet increased (P ≤ 0.05) ending BW, DMI, ADG, and G:F linearly as supplemental RUP increased from 0.5% to 4.2%. In experiment 3, there were no differences (P ≥ 0.56) in DM digestibility and organic matter digestibility between silage harvest DM and intake level. Neutral detergent fiber (NDF) intake was reduced (P < 0.01) for lambs fed the delayed harvest corn silage compared to earlier corn silage harvest. As silage harvest was delayed from 37% to 43% DM, NDF digestibility decreased (P < 0.01) from 64.39% to 53.41%. Although increasing corn silage concentration in place of corn in finishing diets reduced ADG and G:F, delayed silage harvest did not affect performance of finishing cattle. Delayed silage harvest in growing cattle resulted in lower ADG and G:F, possibly due to increased starch or maturity leading to decreased NDF digestibility. The addition of RUP to silage-based, growing diets improves performance by supplying more metabolizable protein and suggests RUP of corn silage is limiting.
摘要译文
三个实验评估了延缓玉米青贮饲料的收获，青贮饲料的浓度以及补充蛋白质的来源对生长和精整日粮的性能和营养消化率的影响。实验1使用了180头杂交一岁ste牛皮（体重[BW] = 428； SD = 39公斤），以评估含40％改良酒糟和可溶物的日粮中玉米青贮干物质（DM）（37％或43％），并用青贮饲料（占日粮DM的15％或45％）代替玉米。实验2使用了60头杂种公牛（体重= 271； SD = 32公斤），以评估青贮饲料中玉米青贮饲料干物质（37％或43％）和对瘤胃不可降解蛋白（RUP）的补充（日粮干物质的0.5％，1.4％，2.4％，3.3％或4.2％）的反应增加饮食。实验3使用了9只杂交羔羊（体重= 30.1； SD = 4.1 kg），以评估随意饲喂或限制在BW的1.5％的青贮饲料中37％或43％DM玉米青贮饲料的养分消化率。在实验1中，随着玉米青贮饲料浓度从15％增加到45％，平均日增重（ADG）和增重与饲料比（G：F）降低（P≤0.04）。饲喂45％玉米青贮饲料的ste牛的—体调整后的最终体重和热car体重量（HCW）较低（P≤0.04），而等天则为15％。当玉米青贮饲料的干物质含量从37％增加到43％时，干物质摄入量（DMI），ADG，G：F或HCW均无差异（P≥0.30）。在实验2中，随着玉米青贮饲料的DM从37％增加到43％，ADG和G：F降低（P≤0.04）。饮食中补充RUP的增加（P≤0.05）以BW，DMI，ADG和G：F线性增加，因为补充RUP从0.5％增加到4.2％。在实验3中，青贮饲料DM与摄入水平之间的DM消化率和有机物消化率没有差异（P≥0.56）。与延迟收获的玉米青贮饲料相比，延迟收获的玉米青贮饲料喂养的羔羊中性洗涤剂纤维（NDF）的摄入量减少了（P <0.01）。由于青贮饲料的采收率从37％延迟到43％，NDF消化率从64.39％下降（P <0.01）到53.41％。尽管在日粮中增加玉米青贮饲料中玉米的含量降低了ADG和G：F，但青贮饲料收获的延迟不会影响牛的肥育性能。生长牛的青贮饲料延迟收获导致ADG和G：F降低，这可能是由于淀粉或成熟度增加导致NDF消化率降低所致。在以青贮饲料为基础的生长日粮中添加RUP可以通过提供更多可代谢的蛋白质来改善生产性能，这表明玉米青贮饲料的RUP受到限制。
F Henry Hilscher[1];Dirk B Burken[1];Curt J Bittner[1];Jana L Gramkow[1];Robert G Bondurant[1];Melissa L Jolly-Breithaupt[1];Andrea K Watson[1];Jim C MacDonald[1];Terry J Klopfenstein[1];Galen E Erickson[1]. Impact of corn silage moisture at harvest on performance of growing steers with supplemental rumen undegradable protein, finishing steer performance, and nutrient digestibility by lambs[J]. Translational Animal Science, 2019,3(2)