UCD Lyons Research Farm, Lyons Estate, Celbridge, Naas, Co. Kildare W23 ENY2, Ireland; School of Veterinary Medicine, University College Dublin, Belfield, Dublin 4 D04 W656, Ireland.
School of Veterinary Medicine, University College Dublin, Belfield, Dublin 4 D04 W656, Ireland.
J Dairy Sci. 2020 Feb;103(2):1416-1430. doi: 10.3168/jds.2019-17078. Epub 2019 Nov 27.
A systematic review and meta-analysis were conducted to estimate the effect of herb species on milk production and urinary nitrogen (UN) excretion from grazing dairy cows. Grazing swards consisting of herb species grown with either a grass species or a grass and legume (multispecies swards) were compared with non-herb-containing swards consisting of a grass species grown as a monoculture or grass-legume swards (simple swards). A literature search was completed using the online databases CAB Direct, Web of Science, and Google Scholar, using the search strategy "dairy cow", "herb OR forb OR phorb", and "grazing". Milk production data, variance, and sample size were required for eligibility. In all, 116 studies were identified. Following eligibility screening, 11 papers from 6 journals, published between 2006 and 2018, were available for analysis. Studies were from New Zealand (N = 7), Australia (N = 3), and the United States (N = 1). The population was either Holstein Friesian or Holstein Friesian × Jersey dairy cows, with a range in mean daily milk yield (MY) from 12.1 kg to 34.7 kg (mean = 18.6 kg). A total of 25 comparisons were used for milk production analysis, with 324 and 284 cows included in multispecies and simple sward groups respectively. Data analysis was conducted in R using a random effects, robust variance estimation model (R Foundation for Statistical Computing, Vienna, Austria). Heterogeneity was reported using the I statistic. Milk production was significantly increased. Analysis of MY resulted in a weighted mean difference (WMD) of +1.20 kg/d (95% CI = 0.90, 1.49; I = 4%). Fat and protein kg were also significantly increased (WMD +0.06 kg/d; CI = 0.01, 0.11). Urinary nitrogen excretion was estimated from milk urea nitrogen when reported (n = 6). A WMD of -28.1 g of N/d (95% CI = -81.1, 24.9) was generated, with heterogeneity high among studies (I = 75%). This meta-analysis shows the potential benefits of multispecies swards. Although we saw no significant difference in UN excretion, an increase in milk production was found.
本研究进行了系统评价和荟萃分析，以评估草本物种对放牧奶牛产奶量和尿氮（UN）排泄的影响。与由单一草种或草豆科混播（简单草地）生长的非草本草地相比，比较了由草本物种与草种或草豆科混播（多物种草地）生长的草地。使用在线数据库 CAB Direct、Web of Science 和 Google Scholar 完成了文献检索，使用的搜索策略为“奶牛”、“草本植物或杂草 OR 弗伯”和“放牧”。需要有牛奶产量数据、方差和样本量才能符合条件。共有 116 项研究符合条件。经过资格筛选，有 6 种期刊的 11 篇论文符合条件，发表于 2006 年至 2018 年期间，可用于分析。研究来自新西兰（N = 7）、澳大利亚（N = 3）和美国（N = 1）。该种群为荷斯坦弗里斯兰或荷斯坦弗里斯兰×泽西奶牛，平均日产奶量（MY）范围为 12.1 至 34.7 千克（平均值为 18.6 千克）。共进行了 25 次产奶量分析，多物种草地组和简单草地组分别纳入 324 头和 284 头牛。数据分析在 R 中进行，使用随机效应、稳健方差估计模型（R 基金会，维也纳，奥地利）。使用 I 统计量报告异质性。产奶量显著增加。对 MY 的分析得出加权平均差异（WMD）为+1.20 千克/天（95%CI = 0.90，1.49；I = 4%）。脂肪和蛋白质千克也显著增加（WMD +0.06 千克/天；CI = 0.01，0.11）。当报告时（n = 6），从乳尿素氮中估计尿氮排泄量。产生了-28.1 克/天的 WMD（95%CI = -81.1，24.9），研究之间的异质性很高（I = 75%）。这项荟萃分析表明多物种草地具有潜在的好处。虽然我们没有发现尿氮排泄量的显著差异，但发现产奶量增加了。
