I know that the market wants bigger lambs; it costs just as much to kill and butcher a small lamb as it does a large, so as a result processing costs per kg of carcass are marginally lower. There are some circumstances in which a larger lamb is desirable rather than simply convenient for processors, but there are limits; too big a carcass may not fit in with the standardised production line butchery and packaging requirements of some of the larger retailers, and if it doesn’t suit it may be either heavily discounted or dismissed as not suitable; a situation that I experienced myself many years ago, but with pigs not sheep.

The small pig unit, on a farm I was running at the time, produced some very good cutters with regular batches going into an abattoir supplying a well-known major retailer (beginning with S). Rather than just providing a good carcass it was decided to go one step further and produce an excellent carcass; after all, nobody can argue about better quality, can they? I changed the boar, and the resulting progeny really were some excellent, very well-fleshed cutters with tremendous loins, hams and legs. Unfortunately, not everybody appreciated the quality. After the first batch were finished and dispatched to the abattoir I received a message, via the marketing group I was selling through, simply to say that they needed to seek an alternative outlet for the cutters because the pigs were too good. The exceptionally well-fleshed loins and legs simply did not meet the requirements of the abattoir’s production line butchery; they were too big, they did not suit the standardised packaging.

And they say that supermarkets want quality meat; that’s questionable. In reality they want a good average, a standard product with good eye appeal that can be processed relatively quickly and easily by production line butchery. I suspect that consistency is probably more important than quality and sometimes the two will happen to coincide.

Back to sheep and an apparent fixation with size; I can put a good, well-finished twin lamb out of a 65kg ewe into the market at around 42kg to 44kg at 12 to 14 weeks of age; a single has the potential to get there a lot sooner. At a fixed stocking rate of say 1,500kg per ha (this figure will vary depending on individual situations but is based upon the old standard of one LSU per acre) this equates to 23 ewes at 65kg. If said ewes lamb at, say, 185% (again this figure will vary), this equates to 42.6 lambs per ha. At an average finished liveweight of say 43kg, this produces an output of about 1,830kg of lamb per ha. A larger ewe, say 75kg, at the same stocking rate (1,500kg per ha) would be stocked at 20 ewes per ha lambing percentage, which at the same lambing percentage would produce about 37 lambs or 1,590kg of lamb per ha – a difference of 240kg.

Even if the heavier ewes produced lambs that were on average 2kg heavier at the same age, the difference would still be 165kg in favour of the smaller ewes. In financial terms, at say £2.50 per kg lwt, this difference will equate to somewhere between £412 and £600 per ha, assuming that the heavier lambs can be kept within the medium weight band; lambs that are 45kg or above could attract 3p to 4p per kg lower price, i.e. a further £5 or £6.50 less per ha. To produce the same level of financial output per unit area, lambs from the heavier ewes at the same age would need to average approximately 49.9kg.

Small or medium sized prolific ewes in the same production environment will always produce a greater output in terms of kg lamb per ha than larger ewes. In addition, they all need feeding for 365 days of the year. At an average dry matter intake of between 3% and 4% of liveweight (most support the lower figure), the larger ewe will consume between 110kg and 146kg of dry matter more per year than the smaller. With grazed grass worth about 6p or 7p per kg of dry matter (and rising) that equates to an additional £6.60, at the lowest figure, to £10.22 per head to feed a larger ewe simply to produce less lamb per ha, and this ignores the impact of additional veterinary costs, feed costs etc. for the larger sheep and lambs.

Ewe weight will have some impact where supplementary feeding is required; for example, in late pregnancy and early lactation and where housed for lambing, larger ewes require more space, more bedding etc. Precise figures will vary depending on individual farm circumstances and any breed effect, for example, good foragers capable of using grass and forage more effectively will obviously perform better, although this effect will be similar across a range of ewe sizes, but it does serves to illustrate a point.

Sheep size will also have an impact on a farm’s carbon footprint, in particular methane emissions; recent research in New Zealand indicates that mature size has an impact on methane emissions; a bigger sheep produces more, whereas twinning reduces the level of methane produced per lamb. Type of feed also has a significant impact. Rumen fermentation associated with higher levels of hard feed will produce significantly greater levels than forage diets. This is supported by UK research, which also demonstrates that a wider variety of species in permanent pastures favours lower methane outputs than a purely ryegrass sward.

It seems relatively easy to conclude from this that there are significant advantages to be gained by having a sheep system based around a medium-sized, prolific ewe that just happens to be a good and efficient forager, using good, proven terminal sires to produce quality lambs; both to maximise lamb output per ha and to help reduce contributions to greenhouse gasses. Others may draw a different conclusion.

The mention of methane may be a bit of a red flag to some producers, possibly quite a lot of producers if figures from the 2021 Agricultural Statistics and Climate Change report are any indication. Approximately 40% of producers surveyed seemed to be of the view that it was simply not necessary to do anything to mitigate the impact of climate change, a figure that rose to 48% for smaller farms and those with grazing livestock (i.e. ruminants).

This is quite an alarming statistic that really does the industry no credit, particularly in the wake of the recent COP26 talks, where methane emissions were fairly high profile and emissions from ruminants very much in the firing line, particularly from some of the fringe organisations. As an industry we are a relatively soft target, and in spite of some excellent work by industry organisations such as the NFU and NSA, we often fail to speak with a common and effective voice in our own defence. While this is not surprising with the number of individual, disparate and diverse sheep enterprises we have across the country, ignoring the problem does not make it go away.
By and large the anti-livestock lobby have overstated their methane case in pursuit of their own agendas, often choosing to ignore the fact that methane is a flow gas which breaks down in the atmosphere over about ten years, with the result that methane produced by our sheep today will simply replace the degraded methane emitted by their forbears ten years previously. This is quite unlike CO2, which once released into the atmosphere is there forever, although some will be recycled.

As UK sheep numbers are in decline, sheep today are replacing about 7% less methane than that produced by their flock mates four years ago. Compared to most other sectors, across all industries, this alone represents significant progress; we need to be more outspoken in defence of our industry.

There has been a great deal of discussion around tree planting. It has its place, but it is not the panacea that many would like to assume. Grass will also recycle and absorb significant quantities of CO2 and will continue to do so long after most deciduous trees have lost their leaves and stopped photosynthesising in the autumn. In addition, trees are not just trees; a dense plantation of conifers contributes very little environmental or biodiversity benefit and does nothing for soil health; benefits are significantly less than from either broad-leaved woodlands or good permanent pasture.

To be fair, the 2021 report also showed that the reason for much of the climate change inactivity on the part of producers was both a lack of meaningful information and the fact that much of the information that was available was confusing and sometimes even contradictory. DEFRA needs to take as much from the report as producers. I suspect that many more sheep producers would be quite happy, keen even, to make a contribution to some of the solutions if they had access to some meaningful guidance and could see a clear way forward, with the proviso of course that any contribution they are expected to make towards so called public goods is appropriately rewarded; sheep farming is, after all, still a business.