Department of Animal and Poultry Science, University of Saskatchewan, Saskatoon, SK S7N 5A8, Canada.
Agriculture and Agri-Food Canada, Lethbridge Research and Development Centre, Lethbridge, AB T1J 4B1, Canada.
J Anim Sci. 2023 Jan 3;101. doi: 10.1093/jas/skad043.
This study evaluated the effects of forages (BarS vs. STR) that differ in the uNDF concentration and FI rate on ruminal fermentation, total tract barrier function, reticulo-ruminal motility, and blood metabolites of beef heifers. Six ruminally cannulated Hereford × Simmental heifers (699 ± 69.1 kg BW) were used in a 6 × 6 Latin square (26 d periods) with a 2 × 3 factorial treatment arrangement. However, 1 heifer was removed from the study after period 2 due to health problems unrelated to treatment, resulting in an incomplete 6 × 6 Latin square design. Barley grain-based diets were formulated using BarS or wheat STR to alter uNDF (7.1% vs. 8.5% DM) with FI rates of 5%, 10%, or 15% of DM. There were limited interactions between the forage type and FI. DM intake was not affected (P ≥ 0.10) by forage type or FI. Use of STR vs. BarS increased uNDF intake (P < 0.001). Increasing FI increased (P < 0.001) uNDF intake for those fed 15% forage. Ruminal pH was not affected (P ≥ 0.10) by forage type; however, cattle fed 5% FI had lesser (P = 0.017) mean ruminal pH and maximum pH (P = 0.018) than those fed 10% and 15% of forage. The total SCFA concentration was not affected by forage type (P = 0.84) but cattle fed the 5% FI rate had lesser (P < 0.001) molar proportion of acetate when compared with cattle fed 10% and 15% forage. Increasing the FI rate decreased the molar proportion of propionate (P < 0.001). Feeding STR relative to BarS decreased (P = 0.041) the reticulo-ruminal contraction duration. In contrast, cattle fed the 10% and 15% FI rates had a greater (P = 0.028) contraction frequency with lower (P = 0.048) contraction area than those fed 5% forage. Plasma glucose, serum insulin, and serum amyloid A were not affected by forage type or FI rate (P ≥ 0.10). Cattle fed 15% forage had lesser (P = 0.040) concentration of serum haptoglobin when compared with cattle fed 5% or 10% forage. In conclusion, forage type used to affect the dietary uNDF concentration, and FI rate act independently suggesting that the provision of STR to increase uNDF reduces reticulo-ruminal contraction duration and total tract permeability but may not affect ruminal pH. Increasing the FI increased dietary uNDF, stabilized ruminal pH, stimulated more frequent reticulo-ruminal contractions, and may decrease the permeability of the gastrointestinal tract and systemic inflammation.
本研究评估了不同中性洗涤纤维浓度和纤维消化率的饲草（BarS 与 STR）对肉牛瘤胃发酵、全肠道屏障功能、反刍-瘤胃运动和血液代谢物的影响。6 头安装有瘤胃套管的荷斯坦×西门塔尔杂种肉牛（699 ± 69.1 kg BW）采用 6×6 拉丁方（26 天周期）设计，进行 2×3 因子处理安排。然而，由于与处理无关的健康问题，有 1 头肉牛在第 2 周期后被从研究中移除，导致不完全的 6×6 拉丁方设计。基于大麦谷物的日粮通过使用 BarS 或小麦 STR 来调节中性洗涤纤维（7.1%与 8.5% DM），纤维消化率为 DM 的 5%、10%或 15%。饲草类型和纤维消化率之间的相互作用有限。饲草类型或纤维消化率对干物质采食量没有影响（P≥0.10）。与使用 BarS 相比，使用 STR 增加了中性洗涤纤维的采食量（P＜0.001）。增加纤维消化率（P＜0.001）会增加 15%饲草采食量的中性洗涤纤维摄入量。瘤胃 pH 不受饲草类型的影响（P≥0.10）；然而，与采食 10%和 15%饲草的牛相比，采食 5%纤维消化率的牛的平均瘤胃 pH 和最大 pH 较低（P=0.017 和 P=0.018）。总短链脂肪酸浓度不受饲草类型的影响（P=0.84），但与采食 10%和 15%饲草的牛相比，采食 5%纤维消化率的牛的乙酸摩尔比例较低（P＜0.001）。增加纤维消化率会降低丙酸摩尔比例（P＜0.001）。与使用 BarS 相比，使用 STR 会降低（P=0.041）反刍-瘤胃收缩的持续时间。相比之下，采食 10%和 15%纤维消化率的牛的收缩频率较高（P=0.028），收缩面积较低（P=0.048），而采食 5%饲草的牛则较低。血浆葡萄糖、血清胰岛素和血清淀粉样蛋白 A 不受饲草类型或纤维消化率的影响（P≥0.10）。与采食 5%或 10%饲草的牛相比，采食 15%饲草的牛的血清结合珠蛋白浓度较低（P=0.040）。总之，饲草类型影响饲粮中性洗涤纤维浓度，纤维消化率独立作用，表明提供 STR 以增加中性洗涤纤维会减少反刍-瘤胃收缩的持续时间和全肠道通透性，但可能不会影响瘤胃 pH。增加纤维消化率会增加饲粮中性洗涤纤维，稳定瘤胃 pH，刺激更频繁的反刍-瘤胃收缩，并可能降低胃肠道通透性和全身炎症。
