Effect of pasture allowance and supplementation with maize silage and concentrates differing in crude protein concentration on milk production and nitrogen excretion by dairy cows
Effect of pasture allowance and supplementation with maize silage and concentrates differing in crude protein concentration on milk production and nitrogen excretion by dairy cows
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DOI：
10.1016/j.livsci.2007.05.019
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发表时间：
2008-04-01
影响因子：
1.8
通讯作者：
Mulligan, F. J.
中科院分区：
文献类型：
--
作者：
Burke, F.;O'Donovan, M. A.;Mulligan, F. J.
将平均产奶时间 (DIM) 140 天的 60 头奶牛（40 头经产奶牛和 20 头初产奶牛）分配到五个处理组，以评估牧草津贴和补充 a) 玉米青贮饲料、b) 高粗浓缩蛋白和 c) 低粗浓缩蛋白对产奶量和氮 (N) 排泄的影响。其中两个处理（HG 和 LG）仅提供牧草（每头牛/天分别提供 20 和 15 公斤干物质 (DM)），而其余三个处理提供每头牛/天 15 公斤干物质 (DM) 的牧草限额，加上每头牛/天 4 公斤 DM 的玉米青贮饲料 (M)、高 CP 浓缩物（CP 浓度为 194 g/kg DM）（HQ 或柑橘果肉（CP 浓度为69 g/kg DM) (LC)。HG、M、HC 和 LC 的总 DM 摄入量 (DMI) 相似，但 LG（每头牛每天 15.2 公斤 DM）低于 HC（每头牛每天 17.4 公斤 DM），对于提供高玉米青贮饲料的奶牛来说，每公斤补充 DM 的牧场 DMI 减少了 0.44、0.45 和 0.54 公斤。补充处理组的产奶量（23.7-24.7 千克/天）高于 LG（20.7 千克/天），但 HG 的乳脂浓度（23.2 千克/天）高于 HG、M 和 LC，但不高于 LG，而 HG 的乳蛋白浓度（34.8 克/千克）高于 LG 和 HG。 HC 记录的 N 和 PDIN 摄入量最高水平（662 和 2502 克/天）和 HC（654 和 2506 克/天），高于 LC，但不高于 LG 和 M。处理 HC 记录的最高 PDIE 摄入量（1743 克/天），高于 LG、M 和 LC，但不高于 HC。 4 克/天）高于 LG 处理，但不高于 HG、M 和 LC。HG 处理的粪便 N 排泄量（171 克/天）高于所有其他处理，而 HG 和 HC 处理的估计尿液 N 排泄量高于 LC（320 克/天）。 HG 的总氮排泄量 (0.68) 低于所有其他处理。本研究的结果表明，补充有限的草量对奶牛的产奶量有很大影响，并且提供低 CP 补充剂的奶牛与提供高 CP 补充剂的奶牛的产量水平相似。 (C) 2007 Elsevier B.V. 保留所有权利。
Sixty cows (40 multiparous and 20 primiparous) averaging 140 days in milk (DIM) were assigned to five treatments to evaluate the effect of pasture allowance and supplements of a) maize silage b) high crude protein concentrate and, c) low crude protein concentrate on milk production and nitrogen (N) excretion. Two of the treatments (HG and LG) were offered herbage only (allowances of 20 and 15 kg dry matter (DM) per cow/day, respectively) while the remaining three treatments were offered a herbage allowance of 15 kg DM per cow/day plus 4 kg DM per cow/day of maize silage (M), a high CP concentrate (CP concentration of 194 g/kg DM) (HQ, or citrus pulp (CP concentration of 69 g/kg DM) (LC). Total DM intake (DMI) was similar for HG, M, HC, and LC but was lower for LG (15.2 kg DM per cow/day) than HC (17.4 kg DM per cow/day). The reduction in pasture DMI per kg of supplement DM ingested was 0.44, 0.45, and 0.54 kg for cows offered maize silage, high CP concentrate, and low CP concentrate, respectively. Milk yield was greater for the supplemented treatments (23.7-24.7 kg/day) than for LG (20.7 kg/day) but not for HG (23.2 kg/day). Milk fat concentration was greater for HC (35.3 g/kg) than for HG, M, and LC but not greater than LG, while milk protein concentration was greater for HG (34.8 g/kg) than for LG and HC but not greater than M and LC. The greatest levels of N and PDIN intake were recorded for HG (662 and 2502 g/day) and HC (654 and 2506 g/day) which were greater than LC but not greater than LG and M. Treatment HC recorded the highest PDIE intake (1743 g/day) which was greater than LG, M and LC but not greater than HG. Output of N in milk was greater on HC (13 4 g/day) than on LG but was not greater than on HG, M, and LC. Faecal N excretion was greater on HG (171 g/day) than on all other treatments while estimated urinary N excretion was greater on HG and HC than LC (320 g/day). Treatment LC had a higher proportion of N output in milk (0.23) than treatment LG but not higher than HG, M and HC treatments. Urinary N expressed as a proportion of total N excretion was lower for HG (0.68) than all other treatments. The results of this study show that there is a large response in milk production to supplementing cows on a restricted grass allowance and that cows offered low CP supplements had similar levels of production to those offered high CP supplements. Nitrogen utilisation was improved by offering supplements of lower CP content. (C) 2007 Elsevier B.V. All rights reserved.