The economics of extensive livestock farming rest on reproduction and weaning rates, which depend heavily on the quantity and quality of available feed. The more you can wean, the more surplus stock you can sell and the more scope there is for selecting genetic improvement. Low weaning rates can kill a business. It all depends on whether your stocking rate is in line with your farm’s grazing or carrying capacity.
The grazing capacity of a piece of land is the realistic number of animals that the vegetation can sustain through the year. The stocking rate is the actual number of animals on that land at any given time. That could be more, or less, than that particular veld’s potential.
Experts warn against trying to increase stocking rates by means of extra feed. This can quickly lead to veld degradation as well as animals that are less adapted to natural veld conditions, which are often harsh. Not all lick ingredients are digested and can upset the soil’s chemistry when excreted.
Matching stock numbers to veld capacity
This is why it’s so important to maintain a realistic stocking rate on your farm. But how many animals can your farm support over the long term?
Unlike feedlot operators, extensive livestock farmers can only guess how much their animals eat out there in the veld every day, and more importantly, how much dry material their flock or herd consumes through the year. It could be more than they think.
It’s generally assumed that a grazing animal will take in between 2% and 3% or more of its liveweight per day, depending on the type of animal, growth, and so on. For example, the feed requirements of animals at different physiological stages are different, even if they have the same body weight.
But using 2% as an indicator, a flock of 500 young sheep weighing 50kg apiece will consume 500kg of grass per day, more than 180 000kg over a year. That’s 18 tons, or 18 bakkie loads. However, they’ll be growing all the time, so intake will increase accordingly. Of course, the veld also grows through the season.
Clearly, you must have some idea of how much fodder your various camps can produce through the year. Mowing a slice of good grass veld for hay could give you an indication of production, but that’s not always possible.
Extensive sheep or cattle farmers who depend almost exclusively on natural veld for fodder sometimes plough and plant a few hectares of oats during a good rainy season. Then they’re always amazed at how quickly that green patch is grazed down by a flock of sheep. One day its there, the next day it’s gone.
Why overstocking damages productivity
Logically, your veld camps, and your farm as a whole, must be able to supply that same amount of feed to sustain the animals. One simply has to know more or less how many hectares of veld are needed to keep a given number of animals in production, all continuously changing their nutritional requirements as the year progresses.
The Department of Agriculture has guidelines based on hectares needed per large stock unit (LSU), which basically is an ox weighing 450kg with a weight gain of 500g per day on grass pasture with a digestible energy (DE) concentration of 55%.
Breaking it down to small stock units (SSU), that works out to 10 lambs weighing 45kg each. Thus, if the department’s recommendation for your ecological region is 12ha of veld per ox, you’ll be able to keep 10 of those young sheep on that area, which is 1,2ha per sheep of equivalent (total) weight. The bigger the sheep the more feed it will eat and the more hectares it needs.
In parts of the Karoo the stocking norm is one adult sheep per 3ha to 4ha. In the very arid west 10 or more hectares are needed per sheep. Good grass veld can sustain one LSU (or ox equivalent) on 5ha to 6ha; planted pastures much more.
But the department’s recommendations are based on the grazing value of veld in good condition, that is veld with a good cover of palatable plants. To prevent overgrazing, stocking rates must be reduced on poorer veld.
Calculating grazing requirements accurately
Also keep in mind that the official guidelines are a bit vague in that cattle, sheep and goats are loosely broken up into big frame, medium frame and small frame categories. Research has shown that the LSU equivalent of cows with the same body weight but different frame sizes is different.
A 450 kg small frame cow might need 12 kg of dry matter (DM) per day and the 450 kg large frame cow 15 kg of DM per day, a full 25% more. Often, stocking rate depends on the breed. The difference in frame size between Merino sheep and mutton breeds has possibly declined over the past decades but meat goats are nearly twice as big as Angora goats.
To get a better idea of your true stocking rate, it’s best to weigh a sample of animals in each age group and then calculate the stocking rate in ha/kg liveweight instead of ha/animal. Then see if the number matches the grazing capacity of the camp or farm in terms of LSU weights.
Keep in mind that a ewe or cow with a suckling at foot has higher nutritional needs than a dry animal of the same kind and weight.
Use the data to plan your stocking rates and fodder flow for the year and factor in the possibility of drought and the effects of climate change. Where rainfall is unpredictable, start the season well below the farm’s grazing capacity and let the flock or herd grow into it. Then sell off surplus stock when the grazing capacity is eventually exceeded.
