1ETH Zurich,Institute of Agricultural Sciences,Universitaetstrasse 2,8092 Zurich,Switzerland.
3Agricultural Education and Advisory Centre Plantahof,Kantonsstrasse 17,7302 Landquart,Switzerland.
Animal. 2019 Jan;13(1):198-208. doi: 10.1017/S175173111800112X. Epub 2018 May 29.
Dairy production systems are often criticized as being major emitters of greenhouse gases (GHG). In this context, the extension of the length of the productive life of dairy cows is gaining interest as a potential GHG mitigation option. In the present study, we investigated cow and system GHG emission intensity and profitability based on data from 30 dairy cows of different productive lifetime fed either no or limited amounts of concentrate. Detailed information concerning productivity, feeding and individual enteric methane emissions of the individuals was available from a controlled experiment and herd book databases. A simplified GHG balance was calculated for each animal based on the milk produced at the time of the experiment and for their entire lifetime milk production. For the lifetime production, we also included the emissions arising from potential beef produced by fattening the offspring of the dairy cows. This accounted for the effect that changes in the length of productive life will affect the replacement rate and thus the number of calves that can be used for beef production. Profitability was assessed by calculating revenues and full economic costs for the cows in the data set. Both emission intensity and profitability were most favourable in cows with long productive life, whereas cows that had not finished their first lactation performed particularly unfavourably with regard to their emissions per unit of product and rearing costs were mostly not repaid. Including the potential beef production, GHG emissions in relation to total production of animal protein also decreased with age, but the overall variability was greater, as the individual cow history (lifetime milk yield, twin births, stillbirths, etc.) added further sources of variation. The present results show that increasing the length of productive life of dairy cows is a viable way to reduce the climate impact and to improve profitability of dairy production.
奶牛生产系统常因温室气体（GHG）排放量大而受到批评。在这种情况下，延长奶牛的生产寿命作为一种潜在的温室气体减排措施正受到关注。本研究基于不同生产寿命奶牛的 30 头奶牛的数据，调查了奶牛和系统的温室气体排放强度和盈利能力。个体的生产力、饲养和个体肠道甲烷排放的详细信息可从对照实验和牛群记录数据库获得。根据实验时生产的牛奶和整个生命周期的牛奶产量，为每头动物计算简化的 GHG 平衡。对于终生生产，我们还包括通过育肥奶牛后代来生产潜在牛肉所产生的排放。这考虑到了生产寿命的变化将影响更换率，从而影响可用于生产牛肉的小牛数量的影响。通过计算数据集中奶牛的收入和全部经济成本来评估盈利能力。排放强度和盈利能力在生产寿命长的奶牛中最为有利，而未完成第一次泌乳的奶牛在单位产品和饲养成本方面的排放表现特别不利，饲养成本大多无法收回。包括潜在的牛肉生产在内，与动物蛋白总产量相关的 GHG 排放量也随着年龄的增长而减少，但总体变异性更大，因为奶牛的个体历史（终生牛奶产量、双胞胎出生、死产等）增加了进一步的变异性来源。本研究结果表明，延长奶牛的生产寿命是减少奶牛生产对气候影响和提高奶牛生产盈利能力的可行方法。
