摘要
Most cow-calf producers utilize pasture grazing during the summer months to maintain favorable growth at lower costs. Recent studies have demonstrated a relationship between the rumen microbiota and important performance traits such as feed efficiency and methane emissions in cattle. However, this has not been studied in pasture-grazed cattle due to the difficulty of collecting rumen samples and measuring production traits in these systems. The objectives of this study were to characterize variation in rumen microbiota composition and fermentation profiles in cattle grazed on different pastures, and to link this variation to feed efficiency and methane emissions. In this study, rumen fluid samples were taken from 60 heifers being tested for residual feed intake (RFI) in feedlot under a 100% barley silage diet. Similarly, rumen fluid samples were subsequently taken from 8 high-RFI (inefficient) and 8 low-RFI (efficient) heifers while grazing as separate herds on forage oats and tested for methane emissions using an open-path Fourier Transform Infrared (OP-FTIR) spectrometry method. Total DNA was extracted from all rumen fluid samples and quantitative real-time PCR (qPCR) was performed to estimate microbial populations. Volatile fatty acid (VFA) concentrations were assessed by gas chromatography. The qPCR results indicated that inefficient cattle had less rumen protozoa on grazing than when they were in the feedlot (2.5 × 106 vs 8.6 × 106, p-value < 0.05). Regardless of RFI, cattle had more total rumen methanogens during grazing than in feedlot (1.5 × 108 vs 0.6 × 108, p-value < 0.05). The VFA profiles showed that grazed cattle had lower acetate:propionate ratios versus feedlot animals (p-value < 0.05), indicating more efficient microbial activity while grazing. In conclusion, compared to feedlot barley diet with silage, grazing on pasture led to divergent rumen microbial composition and changes in VFA production, which may be associated with cattle feed efficiency and methane emission.
摘要译文
大多数牛排生产商在夏季使用牧场放牧，以较低的成本保持有利的增长。最近的研究表明，瘤胃菌群与重要的性能性状之间存在关系，例如牛的饲料效率和甲烷排放。但是，由于难以收集瘤胃样本和测量这些系统中的生产特征，因此尚未在牧场上进行研究。这项研究的目的是表征瘤胃微生物群组成的变化和在不同牧场上放牧的牛的发酵谱，并将这种变异与饲料效率和甲烷排放联系起来。在这项研究中，在100％大麦青贮饲料饮食下，从60个小母牛中采集了瘤胃流体样品。同样，瘤胃流体样品随后从8个高RFI（效率低下）和8个低RFI（高效）小母牛（高效）小母牛取，同时作为在草料燕麦上放牧的牛群，并使用开放式傅立叶傅立叶变换（op-ftir）测试了甲烷排放（op-ftir） ）光谱法。从所有瘤胃流体样品中提取总DNA，并进行定量实时PCR（QPCR）以估计微生物种群。通过气相色谱法评估挥发性脂肪酸（VFA）浓度。 QPCR结果表明，与饲养场相比，在放牧时瘤的瘤瘤原生动物效率低（2.5×10 6 6 vs 8.6×10 6 ，p Value <0.05 ）。不管RFI如何，在放牧过程中，牛的总瘤胃甲烷剂比饲养场（1.5×10 8 vs 0.6×10 8 ，p值<0.05）。 VFA剖面表明，放牧的牛的乙酸较低：丙酸酯比与饲养场动物（p值<0.05），表明在放牧时更有效的微生物活性。总之，与青贮饲料的饲养场大麦饮食相比，放牧的牧场导致瘤胃微生物组成和VFA产生的变化，这可能与牛的饲料效率和甲烷排放有关。
J Liu; N Lansink; E Bork; C Carlyle; G Plastow; ; L Guan. PSI-39 Assessment of Rumen Microbiota in Beef Cattle with Different Feed Efficiency Grazing on an Oat Pasture.[J]. Journal of Animal Science, 2018,96(Sup3)