Feeding the ewe for maximum milk yield

Milk yield increases rapidly after lambing, peaking at three to four weeks into lactation.

Nutrient requirements double after lambing to meet the demands of milk production, sending the ewe into negative energy balance as her feed intake lags behind her nutritional requirements. For example, an 80 kg ewe rearing twins will increase her daily energy and protein requirements by 60% and 44%, respectively.

A plentiful supply of high-quality grass is required if they are to eat sufficient dry matter (DM). Unsupplemented ewes increase their DM intake as pasture height increases from 2 cm to 8 cm (900 to 2,000 kg DM/ha), with peak intake at a sward height of 6–9 cm (1,650 to 2,150 kg DM/ha).

In many situations, sward height will be below 4 cm (1,500 kg DM ha) in early lactation and supplementation is required until grass growth catches up with the ewe’s requirements, as shown in the diagram below.

A guide to concentrate supplement feed intake by sward height for twin rearing ewes

Top tips

• Monitor sward height and kg/DM per ha available and supplement accordingly – a sward height of 4.5–8 cm will provide maximum DMI

If practical:

• Group young ewes together for preferential feeding
• Group ewes for feeding by lamb numbers and BCS

If supplementation is required and you continue to use the same compound feed for lactation as you did before lambing, consider the need for additional magnesium depending on the risk of hypomagnesaemia. During early lactation, demand for magnesium increases to 4–5 g/ewe/day. High-risk scenarios include lush spring grass, especially if nitrogen or potash fertilisers have been applied, and fast-growing grass on soils low in magnesium. The condition is more prevalent in ewes under the most stress, for example, those rearing twin lambs or older animals.

To minimise the risk of hypomagnesaemia:

• Avoid the use of fertilisers containing potash on pasture used for early lactation
• Avoid sudden changes in diet or system of feeding
• Magnesium supplements can be included in concentrates, licks or blocks
• Magnesium can also be added to drinking water or a bolus given to ewes which lasts about three weeks and will see most through the peak risk period
• Provide rock salt to ewes at grass. The sodium in salt interferes with potassium uptake hence reducing the risk of low magnesium uptake