Department of Animal Sciences, College of Agriculture, Isfahan University of Technology, Isfahan 84156-83111, Iran.
Department of Animal Sciences, College of Agriculture, Isfahan University of Technology, Isfahan 84156-83111, Iran.
J Dairy Sci. 2020 Sep;103(9):8034-8047. doi: 10.3168/jds.2020-18499. Epub 2020 Jul 16.
Sugarcane bagasse (SB) is a low-quality roughage source that is often plentiful during times of forage shortage. It is generally less costly compared with other conventional sources of forage. We hypothesized that SB could be used as a source of roughage for dairy cattle by replacing wheat straw (WS), another low-quality forage. This study evaluated the effects of replacing WS with SB in diets offered to mid-lactation dairy cows on milk production and fatty acid profile, intake, digestibility, chewing activity, and ruminal fermentation. Nine multiparous Holstein cows averaging (mean ± standard deviation) 105 ± 12 d in milk, 42.1 ± 2.9 kg of milk/d, and 617 ± 59 kg of body weight were used in a replicated 3 × 3 Latin square with 21-d periods. Treatments were (% of dietary dry matter, DM): (1) 0SB, diet containing 0% SB and 27% WS, (2) 9SB, diet containing 9% SB and 18% WS, and (3) 18SB, diet containing 18% SB and 9% WS. Sugarcane bagasse had greater organic matter (OM; 94.1 vs. 85.1% of DM), neutral detergent fiber (NDF; 86.2 vs. 76.4% of DM), acid detergent fiber (ADF; 62.9 vs. 45.2% of DM), and lignin (19.9 vs. 10.3% of DM) concentration, but less crude protein (CP; 2.63 vs. 3.72% of DM) concentration than WS. Sugarcane bagasse also had greater physically effective NDF (total dietary NDF multiplied by % of TMR on the 8-mm + 19-mm sieves, peNDF; 63.2 vs. 40.6% of DM) and undegraded NDF after 288 h of incubation (uNDF; 35.5 vs. 21.2% of DM) contents than WS. The undegraded NDF after 30 h of incubation (uNDF) content was similar for all diets; however, peNDF concentration and proportion of long particles (retained on a 19-mm sieve) increased linearly as SB inclusion in the diets increased. Cows increasingly sorted against long particles as SB replaced WS. Intakes of DM (26.53 kg/d) and NDF (8.58 kg/d) did not differ among the treatments, but intakes of OM and CP decreased, whereas ADF and uNDF intakes increased with SB inclusion level. Total-tract digestibilities of OM, CP, and NDF decreased linearly as SB replaced WS. Milk yield (37.0 kg/d), energy-corrected milk yield (ECM; 38.2 kg/d), feed efficiency (1.44 kg ECM yield/kg DM intake), and milk composition (fat, 3.89%; true protein, 2.90%) did not differ among diets. Increasing SB concentration of the diet linearly increased rumination time, but ruminal pH (ruminocentesis, 4 h after feeding) decreased. Total volatile fatty acid concentration increased linearly, whereas acetate:propionate decreased linearly, as SB replaced WS. The results indicate that replacement of WS with increasing levels of SB in low-forage diets with similar uNDF concentrations did not affect performance of mid-lactation dairy cows. We conclude that SB can be used as a fiber source in diets fed to dairy cows in mid-lactation; however, the decrease in total-tract digestibility of diets may decrease lactational performance when fed to high-producing dairy cows.
甘蔗渣（SB）是一种低质量的粗饲料来源，通常在饲料短缺时期大量存在。与其他常规饲料来源相比，它的成本通常较低。我们假设 SB 可以替代另一种低质量的饲料——小麦秸秆（WS），作为奶牛的粗饲料来源。本研究评估了在泌乳中期奶牛日粮中用 SB 替代 WS 对产奶量和脂肪酸组成、采食量、消化率、咀嚼活动和瘤胃发酵的影响。9 头经产荷斯坦奶牛，泌乳天数平均（均值±标准差）为 105±12d，产奶量为 42.1±2.9kg/d，体重为 617±59kg，采用 3×3 拉丁方设计，21d 为 1 个周期。处理组（日粮干物质的%，DM）为：（1）0SB，日粮中含有 0%SB 和 27%WS；（2）9SB，日粮中含有 9%SB 和 18%WS；（3）18SB，日粮中含有 18%SB 和 9%WS。与 WS 相比，甘蔗渣具有更高的有机物（OM；94.1% vs. 85.1% DM）、中性洗涤纤维（NDF；86.2% vs. 76.4% DM）、酸性洗涤纤维（ADF；62.9% vs. 45.2% DM）和木质素（19.9% vs. 10.3% DM）浓度，但粗蛋白（CP；2.63% vs. 3.72% DM）浓度较低。与 WS 相比，甘蔗渣还具有更高的物理有效中性洗涤纤维（总日粮 NDF 乘以 TMR 中 8mm+19mm 筛网的%，peNDF；63.2% vs. 40.6% DM）和 288h 孵育后未降解中性洗涤纤维（uNDF；35.5% vs. 21.2% DM）含量。所有日粮的 30h 孵育后未降解中性洗涤纤维（uNDF）含量相似；然而，peNDF 浓度和长颗粒（保留在 19mm 筛网上）的比例随着日粮中 SB 的增加而线性增加。随着 SB 替代 WS，奶牛越来越多地对长颗粒进行分类。DM（26.53kg/d）和 NDF（8.58kg/d）的采食量在处理之间没有差异，但 OM 和 CP 的采食量下降，而 ADF 和 uNDF 的采食量增加。随着 SB 替代 WS，总肠道消化率的 OM、CP 和 NDF 呈线性下降。产奶量（37.0kg/d）、能量校正奶产量（ECM；38.2kg/d）、饲料效率（1.44kg ECM 产量/kg DM 采食量）和牛奶成分（脂肪，3.89%；真蛋白，2.90%）在日粮之间没有差异。随着 SB 浓度的增加，反刍时间呈线性增加，但瘤胃 pH（饲喂后 4h 瘤胃液）下降。总挥发性脂肪酸浓度呈线性增加，而乙酸：丙酸呈线性下降，随着 SB 替代 WS。结果表明，在低饲草料日粮中，用 SB 替代 WS，同时保持相似的 uNDF 浓度，不会影响泌乳中期奶牛的生产性能。我们得出结论，SB 可以作为奶牛泌乳中期日粮中的纤维来源；然而，当用于高产奶牛时，日粮的总肠道消化率降低可能会降低泌乳性能。
