Sustainability is one of the most often discussed issues within food production, yet although it appears to be a relatively simple concept, the definition varies considerably. To some, sustainable farming conjures visions of small-scale farms and native breeds; to others, it means improving efficiency through large-scale, intensive production. From a scientific perspective, the consensus definition is a balance between economic viability, environmental responsibility and social acceptability (United Nations, 2005).
In previous decades, sustainability was only considered in the context of farm profitability, whereas the majority of current sustainability discussions relate to greenhouse gas emissions (GHGe), climate change and land use. In the quest to achieve a sustainable future for cattle production, it’s essential to balance all three factors.
Social licence
One of the greatest sustainability issues that the cattle industry needs to overcome is the gap in knowledge and understanding between the producer and the consumer, which, when currently underknown practices are exposed, may lead to accusations that the farming industry lacks transparency. However, there is a significant difference between intentional misrepresentation versus failing to communicate every aspect of on-farm management; yet communication must be improved for producers to gain the social licence to operate in the future (Capper, 2020).
There is a significant difference between intentional misrepresentation versus failing to communicate every aspect of on-farm management; yet communication must be improved for producers to gain the social licence to operate in the future
Farming systems and management practices must therefore be examined, not simply in light of their economic or environmental consequences, but also through the social lens – as if through the eye of the consumer (Figure 1).
Greenhouse gas emission reductions in production
Advances in knowledge and understanding of cattle genetics, nutrition, health and management over the past century have resulted in significant gains in the productivity and efficiency of developed livestock systems, and therefore, reduced environmental impacts per kilogram of milk or meat produced. The most extreme gains have been seen in the United States (US), where the move towards large-scale farming has conferred 63 percent reductions in GHGe/kg of milk between 1944 and 2007 (with a further 19 percent reduction between 2007 and 2017), and an 18 percent reduction/kg of beef between 1977 and 2007 (Capper et al., 2009; Capper, 2011; Capper and Cady, 2020).
Approximately 55 percent of the gains made in US dairy productivity between 1980 and 2006 were due to genetic improvement
Obviously, biological limits must exist for milk yields or growth rates, and efficiencies of scale must eventually plateau. However, given that the US-based dairy cow that holds the world record for 365-day milk production yielded 35,437kg, it is clear that further genetic gains may still be available. Indeed, Shook (2006) reported that approximately 55 percent of the gains made in US dairy productivity between 1980 and 2006 were due to genetic improvement.
Optimal cattle reproduction
Despite the importance of optimal cattle reproduction as a key performance indicator (KPI) within both dairy and beef operations, there are relatively few studies that have quantified sustainability impacts. In terms of dairy GHGe, Garnsworthy (2004) reported that improving fertility to meet ideal KPI (70 days to first insemination, 70 percent oestrus detection rate, 65 percent and 60 percent conception rates to first and subsequent artificial insemination (AI), respectively) would reduce herd enteric methane emissions by 21 to 24 percent. This was primarily because of a reduction in replacement heifers within the herd, with lesser effects of calving interval (Figure 2).
With regard to beef production, it is not surprising that as efficiency improves and the proportion of cows bearing a live calf increases, GHGe per kilogram of beef decrease, with 17.8 percent reductions conferred by improving from a 75 percent calving rate to a 100 percent calving rate (Capper, 2013).
Sexed semen
A growing number of processors and retailers have noted the reductions in GHGe associated with producing beef from dairy calves. For example, van Selm et al. (2021) modelled the impact of replacing calves from suckler cattle systems in New Zealand with Jersey-cross dairy calves, and demonstrated that beef produced from dairy calves had GHGe 29 percent lower per kilogram carcass weight.
To be fair, this is a GHGe accounting issue rather than an inherent biological or efficiency advantage – the environmental gain is afforded to dairy calves because a considerable proportion of the dam’s resource use and GHGe can be allocated to milk production (Murphy et al., 2017). However, dairy beef systems still have considerable potential to improve both profitability and GHGe by making the most efficient use of surplus calves, especially if sexed semen is used to further differentiate between dairy heifers intended as replacements and crossbred bulls for beef rearing systems.
Dairy beef systems still have considerable potential to improve both profitability and GHGe […] especially if sexed semen is used to further differentiate between dairy heifers intended as replacements and crossbred bulls for beef rearing systems
Indeed, Pahmeyer and Britz (2020) modelled the effects of using sexed semen and cross-breeding on German dairy farms, showing that annual profit increased by up to €568/cow (at an average of €79.42/cow) with the greatest benefits of sexed semen being seen in herds that had high heifer replacement rates. Taking a combined technology approach, the individual effects and interactions between using sexed semen, beef semen, genomic testing and crossbreeding on Swedish dairy farms were investigated by Clasen et al. (2021) via a modelling exercise.
Not entirely surprisingly, the highest economic returns resulted from combining all four strategies, with an average improvement of €58/cow (Figure 3). The greatest gains also resulted from using sexed semen in 90 percent of herd heifers, which is logical given that these cattle should have, on average, the highest genetic merit of the cattle in the milking herd.
The only study that appears to have assessed the GHGe implications, again using a modelling approach, is that of Holden and Butler (2018) who reported the effects of sexed semen usage and moving from 50:50 to 78:22 dairy:suckler beef in Irish dairy systems. This study filled an important knowledge gap that many have failed to consider, ie the knock-on effects of changing calf output from dairy production on suckler herd sustainability. The modelled changes increased the economic value of dairy beef to the industry by 60.4 percent and reduced GHGe per tonne of beef by 24.6 percent, assuming that the suckler herd contracted in response to a greater contribution of dairy calves to total beef.
The benefits of high progesterone synchronisation
The sustainability benefits of sexed semen use are best realised when cows are in the optimum reproductive status for conception. Within this, the importance of progesterone levels both before and after AI has become increasingly recognised.
A recent study by Kerby et al. (2021) revealed that heifer synchronisation using a six-day progesterone device/two dose prostaglandin F2 alpha (PGF) protocol using sexed semen achieved a conception rate to first AI of 53.5 percent and 62 percent in spring block-calving and autumn block-calving herds, respectively. When the spring calving costs were analysed, the net financial benefit of the synchronisation programme was considered to be at least £88.55/heifer.
High circulating progesterone levels delivered during synchronisation have been shown to improve the quality of pre-ovulatory follicles (Lonergan, 2011; Wiltbank et al., 2014), provide a longer duration and enhanced expression of oestrus enabling better detection (Lopez et al., 2004), and offer more predictable ovulation (Block et al., 2006; Walker et al., 1996) and competent oocytes (Lonergan, 2011), while enhancing endometrial function (Lonergan et al., 2013) and optimal embryo quality (Rivera et al., 2011; Diskin et al., 2006).
PRID DELTA delivers the highest circulating progesterone levels (van Werven et al., 2013) of any device on the UK market as a result of the 29 percent larger surface area in contact with the vaginal wall and the fact that it contains 12 percent more progesterone per device. It is always advisable to have a conversation with your client about the right protocols their your farm.
Final thoughts
A recent YouGov (2019) study reported that concerns over animal welfare were a primary motivation for consumers reducing or eliminating meat from their diet. Possibly the greatest sustainability benefit of sexed semen is therefore its potential for solving one of the major social acceptability issues of dairy production – the fate of dairy bull calves (Rutherford et al., 2021).
Calves being euthanised on-farm simply because rearing them is economically unviable is utterly unacceptable to people outside agriculture, as evidenced by the inevitable outcries whenever this practice enters the consumer consciousness. It’s clear that the practice must be eliminated to gain consumer trust and confidence, with sexed semen providing considerable opportunities to facilitate the no-euthanasia pledges made by processors and retailers.
The proportion of consumers viewing these [reproductive technologies] in a negative light increased with the perceived artifice or invasiveness of the practice
One small caveat remains, however: although the technological advances that allow us to find the answer to almost any question and talk with colleagues thousands of miles away have been widely embraced, we must consider new or existing farm technology use from the consumer viewpoint.
Pieper et al. (2016) surveyed attitudes of German consumers to reproductive technologies used in farm animals and reported that the proportion of consumers viewing these practices in a negative light increased with the perceived artifice or invasiveness of the practice. Fifty-three percent of consumers were opposed to the use of sexed semen, 58 percent to embryo transfer, 65 percent to fertility programmes and 81 percent to cloning.
As with any survey, results may have been biased by the question formatting: for example, “Are you concerned about hormones being injected into dairy cows?” would be expected to yield different answers to, “What are your top three concerns about dairy farming?” Nevertheless, the results revealed a general lack of awareness by consumers regarding reproductive technologies and therefore a need for improved outreach and education.
We must therefore be prepared to enter conversations that we have traditionally avoided […] and communicate the sustainability advantages of cattle reproductive technologies to the consumer
As an industry, we must therefore be prepared to enter conversations that we have traditionally avoided, to move outside our comfort zones and to communicate the sustainability advantages of cattle reproductive technologies to the consumer. Ultimately, a sustainable future for ruminant production will be independent of either economic viability or environmental responsibility if the market ceases to exist for milk and meat because of a lack of consumer confidence. However, if we improve genetic gains, technology adoption and GHGe while communicating better with consumers, we should be able to enhance economic viability, environmental impacts and social acceptability for both dairy and beef systems, both now and in the future.
