Defining breeding objectives for sustainability in cattle: challenges and opportunities.

This paper reviews breeding objectives of the current global cattle industry and outlines existing challenges and opportunities for improving sustainability in the livestock sector through genetic selection. Cattle breeding programs have historically been focused on generating profit by selecting for high-producing animals and broadened to include traits related to health, reproduction, fertility, and efficiency. Now, cattle industries around the world are using genetics to reduce their environmental impacts and improve sustainability. Reducing emissions is vital to improve sustainability, and industry leaders have set emission goals to either reduce gross emissions, lower emissions intensity, or reach net-zero. However, additional traits should also be measured and compared in terms of their impact on the broader definition of sustainability. In addition to environmental impact, a sustainable breeding objective must consider profit, animal welfare, farmer wellbeing, and social responsibility. Traits to be considered include direct emissions (e.g. nitrogen and methane), production efficiency (e.g. feed efficiency, growth), closer to biology reproduction and fertility (e.g. oestrous strength and semen quality), health (e.g. calf and transition cow health) and welfare traits (e.g. polled). Many of these novel traits require labour-intensive or expensive phenotyping, resulting in small datasets and low reliability of estimated breeding values. Opportunities exist to overcome this limitation by utilising international collaboration to build large data bases, develop inexpensive and easy-to-measure proxy traits, and expand novel-phenotype reference populations by using female-driven reference populations and young stock and males. Non-economic values can be estimated that quantify the impact that a trait has on societal perspective (e.g. farmer preference) or the environmental impact (methane emissions), and combined with economic weights to calculate aggregate weights for each trait. While validation techniques are still uncertain, the United Nations Sustainable Development Goals may be applied to determine the improvement in sustainability due to genetic selection. This approach allows for various perspectives of sustainability, such as in the developed versus developing world, to be considered. The number and quality of relevant phenotypes are currently the main limiting factors. As confidence continues to grow in the opportunity to improve sustainability through genetic selection, substantial new investment will be required both in phenotyping activities, but also into novel breeding structures and scheme designs that can maximise the value and impact of these phenotypes. This paper reviews breeding objectives of the current cattle industry and outlines existing challenges and opportunities for improving sustainability in the livestock sector through genetic selection. As confidence continues to grow in the opportunity to improve sustainability through genetic selection, substantial new investment will be required both in phenotyping activities, but also into novel breeding structures and scheme designs that can maximise the value and impact of these phenotypes. [ABSTRACT FROM AUTHOR]