Why calves need the right fat levels in their diet

There are multiple and important reasons why calves need fat in their diet. Fat is a source of essential fatty acids, which form important membrane structures in the calf, and have a key association with vitamins. Fat is also a store of energy and can be converted to sugar when the calf most needs it.

Lactose is important too – in fact it is the primary source of energy for a young calf and is especially important during cold weather as sugar is vital for fighting viruses.

But focusing on one feed or one element of feed can undermine good calf rearing and, ultimately, a good calf. Calf rearing is about keeping the calf healthy and, as importantly, developing into a ruminant so it can be weaned successfully and grow.

To achieve this, keep fat levels to a daily maximum of 150g/head while also providing dry feed to ensure calves start consuming this from an early age, says Dr Amanda Dunns, of Bonanza Calf Nutrition. Calf milk intakes should be limited to 600-800g a day so this should contain no more than 25% fat, she advises. “What is written on the label doesn’t stop the calf eating dry feed, it’s how much they are actually fed,’’ Dr Dunn explains.

Rearers are warned that reducing dry intake will result in weaning taking four weeks longer than it needs to – it can take calves four to eight weeks after weaning to match the growth of calves fed less milk and less fat.

Trials have shown that for every 6g of extra fat fed, dry feed intake declines by 2kg, or 5%.

“Rumen and large intestine development is a function of incremental increases and is like a snowball so the earlier calves eat, the more they can voluntarily eat, and the more they can digest at weaning,’’ says Dr Dunn.

Crude Fat level in milk replacer (%)	Fat level at 700g CMR/day (g/day)	Fat level at 1kg CMR/day (g/day)
16	112	160
18	126	180
20	140	200
22	154	220
24	168	240
26	182	260