Twinning in cattle: a pathway for reducing the methane intensity of beef

Abstract

Context Reducing livestock emissions, the largest single contributor to agricultural emissions, is increasingly recognised as a high priority. The low biological efficiency of beef cattle, due to their long gestation period, long generational interval, and propensity to be uniparous, contributes to the high methane emissions intensity (kg CO2-e/kg product) of beef compared to most other food products. Aims We evaluate the potential of increasing the frequency of multiparous births (twinning) as a pathway to reducing the methane intensity of beef and the net methane emissions of intensive beef systems. Methods We simulate a uniparous herd structure and emissions profile using GrassGro™ livestock systems modelling software and then calculate the effects of an increasing frequency of multiparous births (twinning), up to 1.53 calves per cow joined, on methane emissions. Key results Our results demonstrate that beef from calves reared as twins has a 22% lower methane intensity than beef from a single reared calf. Although twinning reduces the methane intensity of beef, at the herd level, net methane emissions could rise by as much as 23% at 1.53 calves per cow joined if overall herd size is allowed to grow through an increased number of calves. If we decrease stocking rates, whilst also increasing twinning rates, it is possible to reduce net emissions by up to 14%, without changing productivity. Conclusions Our results illustrate the significant potential of twinning to decrease the methane intensity of beef and to increase the productivity per cow in intensive beef systems. Implications Despite this, twinning is unlikely to be a viable net emissions reduction pathway – as twinning will increase stocking rate unless herd structure is altered – unless a commercial or policy driver to reduce net methane emissions is established.