North Florida Research and Education Center, University of Florida, Marianna, FL 32446, USA.
Department of Animal Science, University of Minnesota, St. Paul, MN 55018, USA.
J Anim Sci. 2023 Jan 3;101. doi: 10.1093/jas/skac397.
Corn silage is the predominant mechanically harvested forage source for feedlot cattle production in the United States because of high yield. Alternatively, because of multiple cuttings per year and lower annual cost, the use of alfalfa or other forages, may increase opportunities for manure spreading, perennial soil cover, pollinator habitat, and greater carbon sequestration. The objective of this trial was to determine the feeding value of alfalfa haylage when replacing corn silage in growing cattle diets. One-hundred-sixty-five Angus crossbred steers [326 ± 51 kg of body weight (BW)] were blocked by initial BW and randomly assigned to one of 28 pens at the University of Minnesota feedlot. Pens were randomly assigned to dietary growing treatments. The control diet was comprised of (DM basis) 50% corn silage, 19.25% rolled corn grain, 19.25% high moisture corn, 7% dried distillers grains plus solubles, and 4.5% liquid supplement (corn silage control, CS Control). For alfalfa haylage (AH) diets, AH substituted corn silage at 33% (AH 33), 66% (AH 66), or 100% (AH 100). Growth performance measurements [dry matter intake (DMI), average daily gain (ADG) and gain to feed (G:F) ratio] were assessed for 42 to 70 d depending on BW block. Afterwards, steers were fed a common finishing diet until harvested. There was a linear increase in DMI (P < 0.01) with increasing AH inclusion. Replacing CS with AH linearly decreased (P ≤ 0.05) ADG and G:F. No differences (P ≥ 0.10) were observed in finishing performance or carcass traits. Results from this study demonstrated that greater substitution of corn silage with alfalfa haylage in growing diets resulted in greater intake but reduced rate of gain and gain:feed. Despite slower rate of gain, cattle fed alfalfa haylage at increasing proportions during the growing period were able to compensate in BW gains during the finishing period and reached harvest weight and backfat thickness at similar days on feed than those fed corn silage. Based on these results the energy value of corn silage and alfalfa haylage were 3.05 and 2.39 Mcal ME/kg of DM, respectively, when included at 50% of the diet DM.
玉米青贮在美国是主要的机械收获饲料，因为其产量高。而由于每年可收割多次且年度成本较低，苜蓿或其他饲料的使用可能会增加粪肥散布、多年生土壤覆盖、传粉媒介栖息地和更大的碳封存的机会。本试验旨在确定在育肥牛日粮中用苜蓿青贮替代玉米青贮时的饲用价值。165 头安格斯杂交公牛[体重（BW）326±51 kg]按初始 BW 分组，然后随机分配到明尼苏达大学牛场的 28 个围栏中。围栏随机分配到不同的生长处理日粮。对照组日粮由（DM 基础）50%玉米青贮、19.25%辊压玉米粒、19.25%高水分玉米、7%干酒糟及其可溶物和 4.5%液体补充料（玉米青贮对照组，CS 对照组）组成。对于苜蓿青贮（AH）日粮，用 33%（AH 33）、66%（AH 66）或 100%（AH 100）的苜蓿青贮替代玉米青贮。根据 BW 分组，42 至 70 天评估生长性能测量值[干物质采食量（DMI）、平均日增重（ADG）和增重：饲料（G：F）比]。之后，所有育肥牛均用相同的育肥日粮饲喂直至出栏。随着 AH 含量的增加，DMI 呈线性增加（P<0.01）。用 CS 替代 AH 会线性降低 ADG 和 G：F（P≤0.05）。在育肥性能或胴体性状方面未观察到差异（P≥0.10）。本研究结果表明，在育肥日粮中用更多的苜蓿青贮替代玉米青贮会导致更大的采食量，但降低增重速度和增重：饲料效率。尽管增重速度较慢，但在育肥期以递增比例采食苜蓿青贮的牛能够在育肥期补偿 BW 增长，并在相同的饲粮天数达到出栏体重和背膘厚度，与采食玉米青贮的牛相似。基于这些结果，当玉米青贮和苜蓿青贮分别占日粮 DM 的 50%时，玉米青贮和苜蓿青贮的能量值分别为 3.05 和 2.39 Mcal ME/kg DM。
