Pieter Gert Theron - Winner - SHARING Second runner up- Technical - 2024,
Hollard Insure and Farmingportal.co.za and Agri News Net - Young Agri Writers awards -
To shear or not to shear: does shearing of feedlot lambs improve profitability?
In feedlots, where the focus is exclusively on meat production, shearing is often regarded merely as a secondary source of income. Sheep are shorn either at intake or shortly before slaughter and the wool sold off to help cover the running costs of the feedlot. This practice does not take into account the age of the animals or quality of wool produced. Since feedlots generally operate on very small margins, questions have been raised as to whether shearing practices could be adapted to help improve profitability.
Shearing an animal places it under considerable stress. This post-shearing stress is mainly due to the challenges faced by shorn sheep in adapting to their thermal environment. Sheep are able to adapt to a wide range of thermal conditions due to the insulating properties of their fleeces, which creates a microclimate next to the skin. Shearing is therefore always accompanied by some degree of thermal stress, regardless of the season. Once the fleece is no longer available to help regulate temperature in the sheep, other physiological and biochemical pathways are triggered to maintain a homeostatic balance. The upregulation of these pathways will increase the energy expenditure of the animal. The increased energy demands of the sheep can be fulfilled either by bodily reserves or by an external energy source (feed). This means that animals will either have increase feed requirements or use body reserves.
Generally studies have found that shearing increases feed intake in sheep. This has been reported to be true for mature ewes, two-tooth animals and feedlot lambs. Shearing therefore almost always leads to increased feed intake. Unfortunately this generally does not equate to improved growth rates. Most current studies indicate that feed conversion becomes poorer after shearing, meaning producers gain no benefit from shearing their animals.
Seasonal differences are obviously also present, with feed intake usually increasing more after winter shearing than summer shearing. Intake of high-quality feed, like a pelleted feedlot diet, is also less likely to increase than intake of roughage diets.
It then seems reasonable to assume that feedlot lambs should not be shorn in winter as this will only lead to the animals consuming more feed without simultaneously improving growth. At higher ambient temperatures, such as will occur during summer, the answer is not so clear. Since shearing still causes stress, even though the thermal shock will not be as great as in winter, animals will not necessarily show improved growth after shearing. A suggestion would be to avoid shearing as long as the environmental temperature is below the upper critical temperature (UCT) for sheep. The UCT for sheep has been set as 34⁰C for hair sheep and between 30 and 32⁰C for wool sheep. If animals are only shorn when temperatures rise above these limits, excessive heat stress which could lead to depressed feed intake should be avoided while no unnecessary stress due to non-essential shearing will occur either.
Considering the available studies on the subject, two main conclusions can be made. Firstly, it appears that shearing lambs or two-tooth sheep, such as would ordinarily be found in feedlots, leads to increased feed intake by the animals. Secondly, in studies conducted on slaughter lambs, growth rates were not significantly improved by shearing the lambs prior to admittance to the feedlot even though feed intake increased. This means that the FCR of these lambs declined, making it less profitable to finish them off in a feedlot. It is possible that older sheep would display improved growth rates due to the increased feed intake associated with shearing, but this would not benefit feedlotters as mature animals have unfavourable growth rates when compared to lambs and will be less profitable to round off.
It therefore appears that, based on current knowledge, there is little benefit to be gained in production terms from shearing feedlot lambs prior to rounding them off. Shearing per se may decrease profitability by increasing feed costs. Thus, the choice of if and when to shear feedlot lambs should be dependent on whether the wool-on hides or wool clip and shorn hides will provide the most income to the feedlotter. Due to fluctuations in feed costs and wool and hide prices, this will not be a static decision but will be dependent on the market circumstances at any given time.
I grew up on a small sheep farm in the Karoo and because of this upbringing I have an understanding of, and sympathy for, small stock farmers and the challenges they face. This is what motivated me to qualify myself in the field of Animal Science. In 2021 I completed an MScAgric Animal Science degree focusing on developing production models for crossbred sheep. Currently I am engaged in my PhD studies where I am attempting to quantify the effect of weather and climatic conditions on sheep production. I chose to pursue this qualification because I believe it will equip me with the expertise I need to contribute to the sheep industry in South Africa, something I am deeply passionate about.
