Disease Systems, Scotland's Rural College (SRUC), West Mains Road, Edinburgh EH9 3JG, UK; Monogastric Science Research Centre, SRUC, West Mains Road, Edinburgh EH9 9JG, UK.
Disease Systems, Scotland's Rural College (SRUC), West Mains Road, Edinburgh EH9 3JG, UK.
Int J Parasitol. 2017 Sep;47(10-11):633-641. doi: 10.1016/j.ijpara.2017.03.006. Epub 2017 May 18.
Here we provide the first known direct measurements of pathogen challenge impacts on greenhouse gas production, yield and intensity. Twin-rearing ewes were ad libitum fed pelleted lucerne from day -32 to 36 (day 0 is parturition), and repeatedly infected with 10,000 Teladorsagia circumcincta infective larvae (n=16), or sham-dosed with water (n=16). A third group of 16 ewes were fed at 80% of uninfected ewes' feed intake during lactation. Methane emissions were measured in respiration chambers (day 30-36) whilst total tract apparent nutrient digestibility around day 28 informed calculated manure methane and nitrous oxide emissions estimates. Periparturient parasitism reduced feed intake (-9%) and litter weight gain (-7%) and doubled maternal body weight loss. Parasitism reduced daily enteric methane production by 10%, did not affect the methane yield per unit of dry matter intake but increased the yield per unit of digestible organic matter intake by 14%. Parasitism did not affect the daily calculated manure methane and nitrous oxide production, but increased the manure methane and nitrous oxide yields per unit of dry matter intake by 16% and 4%, respectively, and per unit of digestible organic matter intake by 46% and 31%, respectively. Accounting for increased lucerne input for delayed weaning and maternal body weight loss compensation, parasitism increased the calculated greenhouse gas intensity per kg of lamb weight gain for enteric methane (+11%), manure methane (+32%) and nitrous oxide (+30%). Supplemented with the global warming potential associated with production of pelleted lucerne, we demonstrated that parasitism increased calculated global warming potential per kg of lamb weight gain by 16%, which was similar to the measured impact of parasitism on the feed conversion ratio. Thus, arising from a pathogen-induced feed efficiency reduction and modified greenhouse gas emissions, we demonstrated that ovine periparturient parasitism increases greenhouse gas intensity. This implies that ewe worm control can not only improve production efficiency but also reduce the environmental footprint of sheep production systems.
我们提供了病原体挑战对温室气体产生、产量和强度影响的首次直接测量。从妊娠第-32 天到第 36 天（第 0 天是分娩），双胎母羊自由采食颗粒紫花苜蓿，然后反复用 10000 条捻转血矛线虫感染幼虫（n=16）或用水假处理（n=16）。第三组 16 只母羊在哺乳期按未感染母羊采食量的 80%喂养。在呼吸室中测量甲烷排放（第 30-36 天），而在第 28 天左右测量全肠道表观养分消化率，以计算粪便甲烷和氧化亚氮排放的估算值。围产期寄生虫感染降低了采食量（-9%）和羔羊体重增加（-7%），并使母体体重损失增加一倍。寄生虫感染使肠道甲烷日产生量减少 10%，但不影响每单位干物质采食量的甲烷产量，而是使每单位可消化有机物采食量的甲烷产量增加 14%。寄生虫感染不影响每日计算的粪便甲烷和氧化亚氮的产生，但使每单位干物质采食量和每单位可消化有机物采食量的粪便甲烷和氧化亚氮产量分别增加 16%和 4%，增加 31%。考虑到为延迟断奶和母体体重损失补偿而增加的紫花苜蓿投入，寄生虫感染使肠道甲烷（+11%）、粪便甲烷（+32%）和氧化亚氮（+30%）每公斤羔羊增重的温室气体强度计算增加。加上颗粒紫花苜蓿生产相关的全球变暖潜势，我们证明寄生虫感染使每公斤羔羊增重的计算全球变暖潜势增加了 16%，这与寄生虫感染对饲料转化率的影响相似。因此，由于病原体引起的饲料效率降低和温室气体排放的改变，我们证明绵羊围产期寄生虫感染会增加温室气体强度。这意味着母羊蠕虫控制不仅可以提高生产效率，还可以减少绵羊生产系统的环境足迹。
