A meta-analysis of feeding strategies for dairy cattle performance and greenhouse gas mitigation across the world

Studies on the effects of cattle feeding strategies on greenhouse gas emissions are fragmented and cannot provide a global comparison of the feeding management practices that lead to optimal production while substantially reducing methane (CH 4 ) and ammonia (NH 3 ) emissions. The present study explains variability in enteric CH 4 , NH 3 mitigations and cattle milk performance due to several diet composition and structure, feed management, breeding, animal experimental designs and CH 4 measurement tools. Effects from 80 treatments were meta-analyzed from an initial 4394 screened papers and we retained 31 articles distributed across 15 countries on four continents. Minerals in feed additive types increased milk yield the most (90%) and, concomitantly, reduced CH 4 production by 33%. Feed additive dosage ranging between 1-4% also contributed to increasing milk yield by 47% while reducing CH 4 by 58%. Meanwhile the impact of 3-nitrooxypropanol (3-NOP) feed additive on health safety is still controversial. Although a partial mixed ration system highly contributed to milk yield (102%), it did not contribute to CH 4 reduction as much as a total mixed ration system (39%). The highest CH 4 reduction levels were recorded with GreenFeed (80%) and a rotating experimental design (37%). The Holstein cattle breed was more productive with an increase of 46% of milk production while reducing CH 4 by 34%. Grass forage increased NH 3 by 5% while crop forage reduced it by 21%. Agriculture can effectively reduce its emissions and contribute to climate-neutral goals as part of a coordinated, global effort involving multiple sectors. • Efforts to reduce enteric greenhouse gases emission whereas increasing animal production is a global challenge • Minerals supplementation increased milk yield by 90% while methane production reduced by 33% • Overall, the feed additive dose of 1-4% increased milk yield by 47% and reduced methane production by 58% • Holstein breed was more productive, increasing milk yield by 46% and decreasing methane by 34% • Grass forage increased ammonia by 5% while crop forage reduced it by 21%.