Salt has many great uses and can be an important ingredient in most supplementary feeds, but when intakes exceed 20 grams per head per day there is often no further nutritional benefit. Cattle require between 15-20 grams of salt per day for osmotic regulation and after that, the excess is excreted by the renal system. A cow eating 300g/day of a 10% salt lick is consuming 30g of salt per day which is already exceeding the upper limits of the animals?۪ salt requirements. Essentially, while salt is a cheap limiter, there is no further nutritional value from feeding more than the animal needs and your money will be better spent on an ingredient with nutritional benefit.
Urea can be used as a limiter as it brings intakes back by about 40-60grams/head/day. However, it must be used with caution because if intakes are too high, it may be dangerous to increase urea without first controlling intakes. Matching urea levels to the class/weight of stock, and the feed situation is the best way to feed urea rather than using it as a bittering agent, as it takes out room for beneficial protein meals such as copra and cottonseed meal.
Ammonium sulphate is a source of non-protein nitrogen (NPN) with a very bitter taste. The sulphur in ammonium sulphate is required by rumen microbes to manufacture several amino acids that help with the conversion and break down of urea into nitrogen. Therefore, ammonium sulphate can be used as an effective limiter, as well as providing the benefit of additional NPN and sulphate. Due to these benefits, ammonium sulphate is a commonly utilised limiter.
Phosphorus (P) is an extremely important mineral with a list of nutritional benefits that would span the length of the Great Wall of China (not really, but you get the point). Not only are most Queensland soils deficient in phosphorus to varying degrees, a lactating cow alone requires approximately 17-24g P/day. Generally beef cows produce around 10 litres of milk per day, and for each litre of milk she produces, she needs 1.6 grams of phosphorous. This is purely for milk production and not for daily maintenance. In growing animals, 9 grams of phosphorus is needed to produce 1kg of live weight gain (in the form of muscle and bone). This applies not only to growing heifers and steers, but also to pregnant cows growing a calf in utero. It is a fantastic limiter for livestock grazing phosphorus deficient soils, especially given its high unpalatability. It is important to keep in mind that when feeding extra phosphorus that the Ca:P ratio must always be balanced at around 2:1 for ruminants. If it is not, cattle will not utilise the available nutrients effectively, and will likely encounter problems with bone structure.
Rumensin is the wonderful rumen modifier that we use to improve feed efficiency. The standard is to add 3kg to dry lick supplements that have daily consumptions of around 250-300g. As a limiter, we can add up to 4kg to the dry lick. Whilst this has no production benefits, it is extremely bitter and effective in reducing consumptions by around 50grams/head/day. It does not require any extra energy to process this extra kilogram on Rumensin. This is well suited to licks when other limiters such as ammonium sulphate and phosphorus are already present yet consumptions are still too high and need to be decreased.
When choosing a limiter at Top Country, rather than just offering a ?band-aid fix?۪, we take into account your operation, country type, what class of stock you are feeding and for how long you have been feeding. It is important to consider why the cattle are overconsuming, and address this issue, rather than simply apply a quick fix that does not address the underlying issues. Speak to your Top Country nutritionist today to find out how we can help you manage intakes!
Authors: Elsie Dodd & Jen Cook