Wheat bran was once a very common feed ingredient in the UK, and although it seems to have become less popular in recent years in many parts of the world, it still appears to be used widely and remains a useful feed ingredient.
The starch content is, however, high (Typical 23%; 230g/kg), and moderate Sugar (Typical 7%; 70g/kg), so not suitable for EMS/Laminitic horses or ponies. Wheat bran is a good source of Protein (Typical 17%; 170g/kg).
So, wheat bran can be good and bad. It can upset the calcium: phosphorus ratio, which can be bad for bone, especially in youngstock or endurance horses or horses in hard work, and once a week, bran mashes should be avoided as this upsets the hindgut Microbiome! If you feed Wheat bran, feed the same amount every day.
The issue with feeding wheat bran
One of the main issues with feeding wheat bran is the low calcium (Ca) to phosphorus (P) ratio. Normally, we are looking to have a whole diet ratio of at least 2:1 (Ca:P).
The problem with wheat bran is that the ratio of Ca:P is 1:11! i.e. there is 11X more P in wheat bran than Ca. Wheat bran typically has around 11g P per kg, whilst the amount of Ca is only 1g per kg.
So we need to balance the high P and low Ca by adding in a source of calcium, and the most common and cost-effective is limestone flour (Calcium Carbonate). We want to aim for twice as much calcium and phosphorus – a 2:1 Ca:P ratio. But how much limestone flour do we need to add?
How much limestone flour to balance the wheat bran
1kg of wheat bran has 11g of phosphorus and 1g of calcium. To get twice as much Calcium we need to add 2 x 11g P = 22g, minus the 1g of Ca that’s already in the wheat bran.
So, per kg of wheat bran, we need to add 21g of calcium.
Limestone flour is 40% calcium. So 40g calcium per 100g.
We want 21g of calcium, so adding 50g of limestone flour a day would be close (20g). BUT we usually feed by volume not weight e.g. 25ml scoops.
Limestone flour has a density of around 1.1g/ml, so if we fed 2 x 25ml scoops a day (50ml) that would be equivalent to 1.1*50 = 55g limestone = 22g calcium!
A 2.7 litre stubbs scoop holds ~540g wheat bran (density of wheat bran ~0.2g/ml)
If you are feeding wheat bran, for every kg you feed, you should add at least 2 x 25ml (55g) per day of limestone flour.
If you are feeding wheat bran, for every stubbs scoop you feed you should add at least 1 x 25ml (27.5g) per day of limestone flour.
