Zali A, Nasrollahi S M, Khodabandelo S
Department of Animal Science, Campus of Agriculture and Natural Resources, University of Tehran, Karaj, Tehran, 31587-77871, Iran.
Young Researchers Club, Khorasgan (Isfahan) Branch, Islamic Azad University, Isfahan, Iran.
Prev Vet Med. 2019 Feb 1;163:87-92. doi: 10.1016/j.prevetmed.2019.01.003. Epub 2019 Jan 8.
The present study was conducted to evaluate the effect of two new formulas of dietary buffers on intake, total tract digestibility, rumen pH, blood metabolites, and milk production of mid-lactation dairy cows. Nine multiparous cows (594 ± 46 kg BW; mean ± SD) averaging 120 ± 28 days in milk and producing 46.6 ± 3.4 kg/d were randomly assigned to a triplicate 3 × 3 Latin square. During each 21-d period, cows were offered one of three total mixed rations that varied in dietary buffer. The three types of dietary buffer were 1) 11.2 g/kg of dietary dry matter (DM) sodium bicarbonate (SB; control), 2) 8.7 g/kg of dietary DM high buffering capacity formula contained Na (HBNa), and 3) 7.4 g/kg of dietary DM high buffering capacity formula contained K (HBK). Each period was comprised of 14 d of dietary adaptation followed by 7 d of sampling. Measured buffering capacity was 102, 150 and 137 percent of NaHCO for SB, HBNa and HBK, respectively. The amount of Na and K were 270 and 0, 310 and 0, and 250 and 60 g/kg for SB, HBNa, and HBK, respectively. Dry matter intake (DMI) tended (P = 0.06) to be lower with HBK (20.6 kg/d) than SB (21.0 kg/d) and HBNa (21.2 kg/d). No treatment effects were observed on rumen pH (averaged 5.88) and DM digestibility in the total digestive tract (averaged 79.4%). Yields of actual milk (38.1 kg/d) and 3.5% fat corrected milk (31.6 kg/d) were not affected by treatments, whereas yields of solid corrected milk (P = 0.07) and milk fat (P = 0.10) tended to be greater with HBK than SB and HBNa. Milk fat concentration in cows fed HBK was greater than in cows fed other treatments (32.5 vs. 29.5 and 29.6 g/kg; P = 0.04). Concentration of milk protein (32.2 vs. 30.6 g/kg) and lactose (46.8 vs. 44.4 g/kg) also were greater in cows fed HBK than those fed SB (P = 0.02). Efficiency of milk production was greater in cows fed HBK than SB (1.86 vs. 1.80; P = 0.01), whereas efficiency of solid corrected milk production was greater in HBK than SB and HBNa (1.64 vs. 1.51 and 151; P = 0.02). Blood concentration of Ca was higher with HBK compared with SB and HBNa (10.4 vs. 9.7 and 9.9 mg/dL, respectively; P = 0.01). These results indicated that under the current experimental condition, supplementation of dairy cow diet with a high buffering capacity buffer containing 60 g/kg K decreased DMI and improved milk composition and milk efficiency of mid-lactation dairy cows.
本研究旨在评估两种新型日粮缓冲剂配方对泌乳中期奶牛采食量、全消化道消化率、瘤胃pH值、血液代谢产物及产奶量的影响。选用9头经产奶牛（体重594±46 kg；平均值±标准差），平均泌乳天数120±28天，日产奶量46.6±3.4 kg，随机分为3×3重复拉丁方试验设计，每组3个重复。在每个21天的试验期内，给奶牛饲喂三种不同日粮缓冲剂的全混合日粮之一。三种日粮缓冲剂分别为：1）日粮干物质（DM）中添加11.2 g/kg碳酸氢钠（SB；对照组）；2）日粮DM中添加8.7 g/kg高缓冲能力含钠配方（HBNa）；3）日粮DM中添加7.4 g/kg高缓冲能力含钾配方（HBK）。每个试验期包括14天的日粮适应期和随后7天的采样期。测得的缓冲能力分别为SB、HBNa和HBK相对于碳酸氢钠的102%、150%和137%。SB、HBNa和HBK的钠和钾含量分别为270和0、310和0、250和60 g/kg。与SB（21.0 kg/d）和HBNa（21.2 kg/d）相比，HBK组（20.6 kg/d）的干物质采食量（DMI）有降低趋势（P = 0.06）。在瘤胃pH值（平均5.88）和全消化道DM消化率（平均79.4%）方面未观察到处理效应。实际产奶量（38.1 kg/d）和3.5%乳脂校正乳产量（31.6 kg/d）不受处理影响，而固体校正乳产量（P = 0.07）和乳脂产量（P = 0.10）有HBK组高于SB和HBNa组的趋势。饲喂HBK组奶牛的乳脂浓度高于其他处理组（32.5 vs. 29.5和29.6 g/kg；P = 0.04）。饲喂HBK组奶牛的乳蛋白（32.2 vs. 30.6 g/kg）和乳糖浓度（46.8 vs. 44.4 g/kg）也高于饲喂SB组（P = 0.02）。饲喂HBK组奶牛的产奶效率高于SB组（1.86 vs. 1.80；P = 0.01），而固体校正乳生产效率HBK组高于SB和HBNa组（1.64 vs. 1.51和1.51；P = 0.02）。与SB和HBNa相比，HBK组奶牛血液中钙浓度更高（分别为10.4 vs. 9.7和9.9 mg/dL；P = 0.01）。这些结果表明，在当前试验条件下，给奶牛日粮中添加含60 g/kg钾的高缓冲能力缓冲剂可降低DMI，并改善泌乳中期奶牛的乳成分和产奶效率。
