Long-term effect of linseed plus nitrate fed to dairy cows on enteric methane emission and nitrate and nitrite residuals in milk
Long-term effect of linseed plus nitrate fed to dairy cows on enteric methane emission and nitrate and nitrite residuals in milk
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DOI：
10.1017/s1751731115002852
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发表时间：
2016-07-01
期刊：
影响因子：
3.6
通讯作者：
Martin, C.
中科院分区：
文献类型：
--
作者：
Guyader, J.;Doreau, M.;Martin, C.
先前的一项研究表明，硝酸盐和亚麻籽对非泌乳奶牛的甲烷（CH 4）缓解作用。在实际应用之前，在奶牛中使用这种新策略需要进一步调查产甲烷减少的持久性和乳制品中的残留物。本试验旨在研究亚麻籽添加硝酸盐对奶牛肠道CH 4排放和生产性能的长期影响。我们还评估了这种饲喂策略对乳制品中硝酸盐残留、全消化道消化率、氮平衡和瘤胃发酵的影响。共16头泌乳荷斯坦奶牛被分配到两个平行进行17周的随机设计组。饮食基于干物质（DM）：（1）对照（54%玉米青贮、6%干草和40%精料; CON）或（2）对照加3.5%来自亚麻籽的添加脂肪和1.8%硝酸盐（LIN+NIT）。日粮的CP（16%），淀粉（28%）和NDF（33%），并提供每日两次。奶牛自由采食，但第5、16和17周除外，其中饲料限制为干物质摄入量（干物质）的95%，以确保在测量期间完全摄食。每周测量产奶量和泌乳量。每月测定牛奶和奶制品中硝酸盐和亚硝酸盐的浓度。在开路呼吸室中对每日CH 4排放量进行定量（第5周和第16周）。在第17周测定全消化道表观消化率、氮平衡和瘤胃发酵参数。从第4周至第16周，LIN+NIT组的每日体重倾向于较低（平均-5.1 kg/天）。LIN+NIT饮食在6个非连续周期间降低了产奶量（平均-2.5kg/天）。在牛奶和相关产品中未检测到硝酸盐或亚硝酸盐残留。LIN+NIT饮食在试验开始和结束时将CH 4排放减少到相似的程度（平均为-47%，g/天;-30%，g/kg体重;-33%，g/kg脂肪和蛋白质校正的牛奶）。日粮不影响氮效率和养分消化率。在瘤胃中，LIN+NIT不影响原虫数量，但降低总挥发性脂肪酸（-12%）和丙酸（-31%）浓度。我们的结论是，亚麻籽加硝酸盐可能有一个长期的甲烷缓解作用，奶牛和消费牛奶产品从奶牛饲喂硝酸盐可能是安全的硝酸盐和亚硝酸盐残留。需要进一步的工作来优化亚麻籽加硝酸盐的剂量，以避免降低奶牛的生产性能。
A previous study showed the additive methane (CH4)-mitigating effect of nitrate and linseed fed to non-lactating cows. Before practical application, the use of this new strategy in dairy cows requires further investigation in terms of persistency of methanogenesis reduction and absence of residuals in milk products. The objective of this experiment was to study the long-term effect of linseed plus nitrate on enteric CH4 emission and performance in dairy cows. We also assessed the effect of this feeding strategy on the presence of nitrate residuals in milk products, total tract digestibility, nitrogen (N) balance and rumen fermentation. A total of 16 lactating Holstein cows were allocated to two groups in a randomised design conducted in parallel for 17 weeks. Diets were on a dry matter (DM) basis: (1) control (54% maize silage, 6% hay and 40% concentrate; CON) or (2) control plus 3.5% added fat from linseed and 1.8% nitrate (LIN+NIT). Diets were equivalent in terms of CP (16%), starch (28%) and NDF (33%), and were offered twice daily. Cows were fed ad libitum, except during weeks 5, 16 and 17 in which feed was restricted to 95% of dry matter intake (DMI) to ensure complete consumption of meals during measurement periods. Milk production and DMI were measured weekly. Nitrate and nitrite concentrations in milk and milk products were determined monthly. Daily CH4 emission was quantified in open circuit respiration chambers (weeks 5 and 16). Total tract apparent digestibility, N balance and rumen fermentation parameters were determined in week 17. Daily DMI tended to be lower with LIN+NIT from week 4 to 16 (-5.1 kg/day on average). The LIN+NIT diet decreased milk production during 6 non-consecutive weeks (-2.5 kg/day on average). Nitrate or nitrite residuals were not detected in milk and associated products. The LIN+NIT diet reduced CH4 emission to a similar extent at the beginning and end of the trial (-47%, g/day; -30%, g/kg DMI; -33%, g/kg fat- and protein-corrected milk, on average). Diets did not affect N efficiency and nutrients digestibility. In the rumen, LIN+NIT did not affect protozoa number but reduced total volatile fatty acid (-12%) and propionate (-31%) concentrations. We concluded that linseed plus nitrate may have a long-term CH4-mitigating effect in dairy cows and that consuming milk products from cows fed nitrate may be safe in terms of nitrate and nitrite residuals. Further work is required to optimise the doses of linseed plus nitrate to avoid reduced cows performance.