Woodmartin Sarah, McGovern Fiona, Smith Paul E, Boland Tommy M, McGrane Lisa, Monaghan Anthony, Dunne Eoin, Creighton Philip
Teagasc, Animal and Grassland Research and Innovation Centre, Mellows Campus, Athenry, Co. Galway, Ireland.
School of Agriculture and Food Science, University College Dublin, Belfield, Dublin, Ireland.
J Anim Sci. 2025 Jan 4;103. doi: 10.1093/jas/skaf139.
Increasing lamb growth rates directly from pasture and reducing enteric methane (CH4) emissions are key drivers to enhancing production efficiency and achieving more sustainable lamb finishing systems. The objective of this study was to assess the influence of binary sward mixtures of perennial ryegrass (Lolium perenne L.) plus a companion forage on growth performance, enteric CH4 output, reticulo-rumen content weight (RRcw), rumen fermentation parameters and the composition of the rumen microbiome in growing lambs. A randomized block design was employed to investigate 5 treatments, namely, perennial ryegrass (PRG), PRG plus white clover (Trifolium repens L.; PRG + WC), PRG plus red clover (Trifolium pratense L.; PRG + RC), PRG plus chicory (Chicorium intybus L.; PRG + Chic) and PRG plus plantain (Plantago lanceolate L.; PRG + Plan). At weaning, 120 lambs (n = 24 per treatment) were selected in both 2021 and 2022 for CH4 measurement using portable accumulation chambers. A further subset of 60 lambs (n = 12 per treatment) were selected from the initial 120 lambs each year for rumen measurements and sampling. Lambs were weighed fortnightly and drafted for slaughter upon reaching their target live weight (LW). Rumen fluid was harvested using a transoesophageal sampling device postweaning and manually immediately postmortem. The average sward companion forage content was 28% on a dry matter basis. Lambs grazing PRG + WC, PRG + RC, or PRG + Chic had a higher postweaning average daily gain (ADG) (P < 0.001) and an increased lifetime ADG (P < 0.001), compared with lambs grazing PRG. The addition of any companion forage resulted in a reduction in age at slaughter of 16 to 50 d (P < 0.001). Methane production (g/d) and CH4 intensity (g/kg LW and g/kg ADG) were reduced for lambs grazing PRG + WC, PRG + RC, and PRG + Plan (P < 0.001), compared with those grazing PRG. There was a lower relative abundance of Methanobrevibacter (P < 0.001) in lambs grazing PRG + RC over those grazing PRG, PRG + Chic, and PRG + Plan. The presence of Prevotella was more abundant in lambs grazing the legume treatments, PRG + WC and PRG + RC, than those grazing PRG (P < 0.001). The RRcw of the PRG lambs was heavier than lambs grazing PRG + WC, PRG + RC, and PRG + Plan (P < 0.001). These results suggest that the manipulation of pasture species composition is a promising, practical, and feasible strategy to enhance production efficiency and mitigate CH4 from pasture-based lamb production systems.
直接提高羔羊在牧场上的生长速度并减少肠道甲烷（CH₄）排放是提高生产效率和实现更可持续的羔羊育肥系统的关键驱动力。本研究的目的是评估多年生黑麦草（Lolium perenne L.）与一种伴生牧草的二元草地混合物对生长羔羊的生长性能、肠道CH₄产量、瘤网胃内容物重量（RRcw）、瘤胃发酵参数和瘤胃微生物群落组成的影响。采用随机区组设计研究5种处理，即多年生黑麦草（PRG）、PRG加白三叶（Trifolium repens L.；PRG + WC）、PRG加红三叶（Trifolium pratense L.；PRG + RC）、PRG加菊苣（Chicorium intybus L.；PRG + Chic）和PRG加车前草（Plantago lanceolate L.；PRG + Plan）。在断奶时，2021年和2022年各挑选120只羔羊（每个处理n = 24只），使用便携式累积室测量CH₄。每年从最初的120只羔羊中再挑选60只羔羊（每个处理n = 12只）进行瘤胃测量和采样。每两周对羔羊称重一次，达到目标活重（LW）后进行屠宰。断奶后使用经食管采样装置采集瘤胃液，并在死后立即手动采集。以干物质计，伴生牧草的平均草地含量为28%。与放牧PRG的羔羊相比，放牧PRG + WC、PRG + RC或PRG + Chic的羔羊断奶后平均日增重（ADG）更高（P < 0.001），一生ADG增加（P < 0.001）。添加任何伴生牧草都会使屠宰年龄降低16至50天（P < 0.001）。与放牧PRG的羔羊相比，放牧PRG + WC、PRG + RC和PRG + Plan的羔羊甲烷产量（g/天）和CH₄强度（g/kg LW和g/kg ADG）降低（P < 0.001）。与放牧PRG、PRG + Chic和PRG + Plan的羔羊相比，放牧PRG + RC的羔羊中甲烷短杆菌的相对丰度较低（P < 0.001）。在放牧豆科处理（PRG + WC和PRG + RC）的羔羊中，普雷沃氏菌的存在比放牧PRG的羔羊更丰富（P < 0.001）。PRG羔羊的RRcw比放牧PRG + WC、PRG + RC和PRG + Plan的羔羊更重（P < 0.001）。这些结果表明，操纵草地物种组成是提高生产效率和减少基于牧场的羔羊生产系统中CH₄排放的一种有前景、实用且可行的策略。
