Department of Animal and Poultry Science, University of Saskatchewan College of Agriculture Bioresources, University of Saskatchewan, Saskatoon, Canada.
Lethbridge Research and Development Centre, Agriculture and Agri-Food Canada, Lethbridge, Canada.
J Anim Sci. 2020 May 1;98(5). doi: 10.1093/jas/skaa116.
The objective of this study was to evaluate the effect of ammonia fiber expansion (AFEX)-treated wheat straw pellets and a recombinant fibrolytic enzyme on the rumen microbiome, rumen fermentation parameters, total tract diet digestibility, and performance of lambs. Eight rumen cannulated wethers and 60 lambs (n = 15 per diet, 8 rams and 7 ewes) were used in a replicated 4 × 4 Latin square design digestibility study and a complete randomized growth performance study, respectively. Four treatment diets were arranged in a 2 × 2 factorial structure with AFEX wheat straw (0% or 30% AFEX straw pellets on a dietary DM basis replacing alfalfa hay pellets) and fibrolytic enzyme (with or without XYL10C, a β-1,4-xylanase, from Aspergillus niger) as main factors. Enzyme was applied at 100 mg/kg of diet DM, 22 h before feeding. Rumen bacteria diversity Pielou evenness decreased (P = 0.05) with AFEX compared with the control diet and increased (P < 0.01) with enzyme. Enzyme increased (P ≤ 0.02) the relative abundancies of Prevotellaceae UCG-004, Christensenellaceae R-7 group, Saccharofermentans, and uncultured Kiritimatiellaeota. Total protozoa counts were greater (P ≤ 0.04) in the rumen of lambs fed AFEX compared with control, with enzyme reducing (P ≤ 0.05) protozoa counts for both diets. Digestibility of DM did not differ (P > 0.10) among diets, but digestibility of CP was reduced (P = 0.001), and digestibility of NDF and ADF increased (P < 0.05) as AFEX replaced alfalfa. Compared with control, AFEX promoted greater DMI (P = 0.003) and improved ADG up to 42 d on feed (P = 0.03), but not (P = 0.51) over the full ~94-d experiment. Consequently, overall G:F was reduced (P = 0.04) for AFEX when compared with control (0.188 vs. 0.199), but days on feed were lower (P = 0.04) for AFEX (97 vs. 91 d). Enzyme improved DMI of AFEX up to day 70 (P = 0.01), but did not affect DMI of the control diet. Enzyme addition improved ADG of lambs fed both diets in the first 28 d (P = 0.02), but not over the entire feeding period (P ≥ 10). As a result, G:F was improved with enzyme for the first 28 d (P = 0.04), but not overall (P = 0.45). This study shows that AFEX-treated wheat straw can replace alfalfa hay with no loss in lamb growth performance. Additionally, the enzyme XYL10C altered the rumen microbiome and improved G:F in the first month of the feeding.
本研究旨在评估氨纤维膨胀（AFEX）处理的小麦秸秆颗粒和重组纤维酶对瘤胃微生物群、瘤胃发酵参数、全肠道饲料消化率和羔羊性能的影响。8 只瘤胃插管的绵羊和 60 只羔羊（n = 15 个处理，8 个公羊和 7 个母羊）分别用于重复 4 × 4 拉丁方设计消化率研究和完全随机生长性能研究。四种处理日粮采用 2 × 2 因子结构，AFEX 小麦秸秆（日粮 DM 基础上 0%或 30%的 AFEX 秸秆颗粒代替苜蓿干草颗粒）和纤维酶（有或没有 XYL10C，来自黑曲霉的β-1,4-木聚糖酶）作为主要因素。酶在饲喂前 22 小时以 100mg/kg 日粮 DM 的剂量添加。与对照日粮相比，AFEX 处理降低了瘤胃细菌多样性 Pielou 均匀度（P = 0.05），而添加酶则增加了均匀度（P < 0.01）。酶增加了 Prevotellaceae UCG-004、Christensenellaceae R-7 组、Saccharofermentans 和未培养的 Kiritimatiellaeota 的相对丰度。与对照相比，AFEX 处理组羔羊的总原虫数量更多（P ≤ 0.04），而酶处理则降低了两种日粮的原虫数量（P ≤ 0.05）。DM 消化率在日粮间没有差异（P > 0.10），但 CP 消化率降低（P = 0.001），NDF 和 ADF 消化率增加（P < 0.05），因为 AFEX 代替了苜蓿。与对照相比，AFEX 促进了更大的 DMI（P = 0.003）和 ADG 提高，在饲料上达到 42 天（P = 0.03），但在整个~94 天的实验中没有提高（P = 0.51）。因此，与对照相比，AFEX 时的整体 G:F 降低（P = 0.04）（0.188 比 0.199），但 AFEX 的饲喂天数更少（P = 0.04）（97 比 91 天）。酶提高了 AFEX 处理组羔羊在第 70 天的 DMI（P = 0.01），但对对照日粮的 DMI 没有影响。添加酶提高了前 28 天饲喂两种日粮的羔羊的 ADG（P = 0.02），但在整个饲喂期间没有影响（P ≥ 10）。因此，前 28 天的 G:F 因酶而提高（P = 0.04），但整体没有提高（P = 0.45）。本研究表明，AFEX 处理的小麦秸秆可以代替苜蓿干草，而不会降低羔羊的生长性能。此外，酶 XYL10C 改变了瘤胃微生物群，并在喂养的第一个月提高了 G:F。
