Quail M R, Davies I G, Moorby J M, Fraser M D
IBERS, Aberystwyth University, Pwllpeiran Upland Research Centre, Cwmystwyth, Aberystwyth SY23 4AB, UK.
IBERS, Aberystwyth University, Gogerddan, Aberystwyth SY23 3EE, UK.
Animal. 2025 May;19(5):101489. doi: 10.1016/j.animal.2025.101489. Epub 2025 Mar 18.
The availability of baseline emission data across various livestock systems is an essential component of identifying suitable mitigation strategies for the future. However, the comparative CH emissions of different livestock species, particularly those that represent key small ruminants globally (sheep (Ovis aries) and goats (Capra hircus)), have not been explored in the context of diet digestibility and growth potential of the animal. This study aimed to generate baseline data through comparing weaned lambs and goat kids in relation to (1) growth performance, (2) enteric methane emissions, (3) and diet in vivo digestibility of a common medium-digestibility diet that reflects the pasture type that the animals might be expected to graze. Ten castrated lambs (Welsh Mountain breed) and ten goat kids (Cashmere × Boer crossbreed) of an equivalent age postweaning (c. 12 months) (avg. starting weight of 15 kg ± 0.86, and 26 kg ± 1.02, respectively) were offered a grass-nuts diet ad libitum whilst housed in individual pens. Dry matter intake (DMI) of feed was monitored daily throughout an 8-week growth stage, whilst liveweight was assessed weekly. Enteric CH emissions of each animal were recorded for 72 h in methane collection chambers. We found significantly higher liveweight gains for the sheep compared to goats (163 and 84 g/day for lambs and kids respectively; SED = 12.8; P < 0.001), as well as higher DMI (1299.8 vs 881.8 g/day; SED = 64.7; P < 0.001). DM intake was comparable between species on a metabolic liveweight (W) basis. The sheep also produced higher daily CH emissions (26.3 g/day, and 19.4 g/day, respectively; SED = 3.02; P < 0.01) than goats. However, no effect of species was observed on CH emissions per kg W or per kg DMI. The proportion of methane energy excreted expressed as a proportion of diet gross energy (Ym) was similar for both species (4.9 and 4.6% CH E/gross energy intake for lambs and kids, respectively; SED = 0.46), as were apparent whole-tract in vivo DM digestibility, although the sheep had a better feed conversion ratio (FCR) than the goats (6.6 g DMI/ g W gain and 11.5 g DMI/g W gain, respectively; SED = 1.58; P < 0.05). Here, we found that sheep were more efficient than goats when offered an identical diet of grass nuts, giving a higher weight gain than the goats (resulting in a lower FCR), whilst also producing similar CH emissions to the goats on a metabolic LW basis.
获取不同畜牧系统的基线排放数据是确定未来合适减排策略的重要组成部分。然而，尚未在动物日粮消化率和生长潜力的背景下，探究不同家畜物种尤其是全球主要小型反刍动物（绵羊（Ovis aries）和山羊（Capra hircus））的比较性甲烷排放情况。本研究旨在通过比较断奶羔羊和小山羊在以下方面生成基线数据：（1）生长性能，（2）肠道甲烷排放，（3）以及反映动物可能采食的牧场类型的普通中等消化率日粮的体内消化率。十只去势羔羊（威尔士山地品种）和十只同龄（断奶后约12个月）的小山羊（绒山羊×波尔山羊杂交品种）（平均起始体重分别为15 kg±0.86和26 kg±1.02），在单独的围栏中自由采食草籽日粮。在8周的生长阶段，每天监测饲料的干物质摄入量（DMI），同时每周评估体重。在甲烷收集室中记录每只动物72小时的肠道甲烷排放。我们发现，与山羊相比，绵羊的体重增加显著更高（羔羊和小山羊分别为163和84 g/天；标准误=12.8；P<0.001），DMI也更高（分别为1299.8和881.8 g/天；标准误=64.7；P<0.001）。基于代谢体重（W），不同物种间的干物质摄入量相当。绵羊的每日甲烷排放量也高于山羊（分别为26.3 g/天和19.4 g/天；标准误=3.02；P<0.01）。然而，未观察到物种对每千克W或每千克DMI的甲烷排放有影响。两种物种以日粮总能的比例表示的甲烷能量排泄比例（Ym）相似（羔羊和小山羊分别为4.9%和4.6%的甲烷能量/总能摄入量；标准误=0.46），表观全肠道体内干物质消化率也相似，尽管绵羊的饲料转化率（FCR）优于山羊（分别为6.6 g DMI/g体重增加和11.5 g DMI/g体重增加；标准误=1.58；P<0.05）。在此，我们发现，当提供相同的草籽日粮时，绵羊比山羊更高效，体重增加高于山羊（导致较低的FCR），同时基于代谢体重，其产生的甲烷排放与山羊相似。
