Sustainable breeding for beef sexed semen supports net zero progress

J.M.E. Statham, C. Johnson, K. Burton, S. Throup, H. Martineau, RAFT Solutions Ltd, Bishopton Vet Group and Harper & Keele Veterinary School, Wm Morrisons Ltd; T Phipps, Map of Agriculture, UK

This paper includes two key themes:

• I. Success factors for advanced breeding in beef herds
• II. Modelling the benefits for sustainable beef production of female and male sexed semen

Livestock farming is under intense scrutiny regarding the environment, including Net Zero commitments and must deliver these, as well as wider environmental objectives, all whilst balancing energy and cost efficiency to maintain a resilient food supply. The NFU has set industry goals of achieving Net Zero greenhouse gas (GHG) emissions by 2040; however, Morrisons beef supply chain aims to deliver this by 2030. The study modelled how to move the ratio of calves from 50:50 male:female calves to 80:20 male:female calves using male sexed semen for a consequent increase in beef yield and the benefits of using female sexed semen to deliver maternal traits for breeding replacement dams. Understanding how the health, fertility and welfare of beef cattle can be improved encourages optimal efficiency on a sustainable holistic system on the journey to net zero beef.

I. Success factors for advanced breeding in beef herds

Good fertility is at the forefront of a profitable and sustainable livestock enterprise; the optimum fertility performance in cattle farming is achieved by maintaining a calving interval of 365 days. Artificial insemination (AI) is still not commonly used in beef cattle reproduction, with less than 10% of UK beef herds adopting the practice. This is mainly due to inadequate or inappropriate handling facilities, lack of confidence in semen quality and implementation, lack of understanding of the precision management required to achieve optimum results or a combination of these factors. However, AI can have many benefits, including allowing farmers to select sires suited to their herd’s breeding programme (e.g. maternal vs. terminal traits), without the expense of buying and keeping multiple bulls, improving genetic potential and efficiency, all while decreasing GHG emissions. Using bulls in the top 1% of breeding values becomes possible with AI, in contrast to most natural service by stock bulls.

This project used an innovative AI breeding programme in a small cohort of cattle from a progressive, family-run 850-acre farm, running around 160 breeding Stabiliser beef cows and farming 450 acres of arable crops (including wheat and barley). Practical opportunities to adopt precision breeding for transformative genetic progress in beef suckler herds were assessed by enhancing sustainable reproductive success in the first phase of the breeding season.

The health and vaccination status of animals in the cohort were assessed to manage infectious disease. Vaccinations were carried out pre-service to reduce stress during pregnancy and provide cover for the foetus, against challenges such as bovine viral diarrhoea virus (BVD), in the critical first 3 months of gestation. Fluke and parasite control were also taken into consideration. Precision management included nutrition assessment and blood sampling to identify trace element deficiencies that might impede AI success (particularly selenium, cobalt, iodine and copper); the use of precision-release fertility boluses (‘Fertil’ Kersia, UK) provided a controlled dosage for these elements and additional beta-carotene in all study cows. Consistent management with minimal change – including group social factors and grazing/housing – is critical to success.

Before AI, the sourced female-sexed semen was independently assessed by multimodal objective analysis combining CASA (computer assisted semen assessment) with Flow cytometry, delivered by experienced technicians through SemenRate ® (RAFT Solutions Ltd, UK).

II. Modelling the benefits for sustainable beef production of female and male sexed semen

The potential benefit of changes with an increased proportion of male calves was modelled by Map of Agriculture (MoA). Productivity cost benefit, reduction in GHG and other key performance indicators were measured. Assessment of bulls versus heifers showed that there was a 60kg difference in carcass weight at slaughter with heifers taking an additional 10 months to reach the reduced slaughter weight. This resulted in an increase of 7.31kg CO2e/kg beef in emissions intensity for heifers. When the impacts for every 100 calves born in the 80:20 male calf system were compared to the traditional 50:50 system it was shown there was an increase in beef production of 3000kg with a reduction in total emissions of 14256kg CO2e and ultimately a reduction in emissions intensity of 3.23kg CO2e/kg beef in the 80:20 system. Maternal trait benefits from female sexed semen for replacements were also modelled, with increased cow longevity, a reduction in age at weaning and increased fertility rates. Combined, these benefits represent a long-term and permanent enhancement to the herd breeding base.

In conclusion, the sustainable breeding programme could produce additional bull calves by using male sexed semen; this was modelled to produce an additional 3 tonnes of beef per 100 calves per year. As well as clear economic advantages, this precision breeding approach offers significant reductions in GHG emissions intensity – which can be amplified if sexed semen with enhanced maternal traits is additionally used for breeding replacements. Sustainable breeding improvements lead to decreased days to slaughter, reduced waste and increased resource efficiency. Sexed semen also offers a key tool to target maternal genetics in the animals bred as replacements and terminal beef traits in animals less suitable for breeding replacements, producing more efficient and lower emissions beef.

Further work is required to disseminate the findings of this project to the wider beef industry. The outputs from the project will help provide the industry with evidence alongside complementary skills-based training to break down the barriers for uptake of AI and use of sexed semen on beef farms. With an increased uptake in AI, farms will have the opportunity to advance the genetic potential of their herd, increasing productivity and sustainability through increasing yield of beef per year. Rearing the optimal number of replacement animals required for their farm each season will reduce GHG emissions intensity alongside better longevity, weaning performance and beef yield.