Maintain Lamb Growth on Summer Pastures

Key Points:

  • The nutritional value of winter grasses declines as it matures.
  • Growing lambs on mature green feed requires protein and energy supplementation.
  • Supplementation of lush lucerne with grain can significantly boost live weight gain.
  • Feeding a palatable hay (cereal hay) on lucerne can help reduce the risk of ‘Red-gut’.


A combination of soil moisture levels and rising temperatures have seen pasture growth really kick throughout spring. The large amount of feed available in some areas will likely see standing feed utilised in lamb growing operations right up until the new year.

Optimal levels of protein and energy for rapidly growing lambs are 16% protein and 12MJ ME/kg DM of energy. This level of nutrition is common when grazing actively growing winter pastures, like Ryegrass and Phalaris, during the cooler months. However, the nutritional value of winter-dominant pasture declines as it goes to head and matures.

Grazing Maturing Pastures

The diagram below illustrates the protein and energy levels of pastures at different stages of growth. Despite the large volumes of green pasture available, warmer temperatures have seen many winter pastures enter their reproductive phase and go to head (early to mid-flowering stage), stop growing and begin to decline in value. Given this, the best way to utilise these pastures and continue to grow lambs at a reasonable rate is to supplement the pasture with protein and energy.

Pasture value chart
Diagram showing how pasture value changes as it matures

At this time of year, the energy level of most summer pastures is the most limiting factor to achieving rapid growth of grazing lambs. Depending on the quality of pastures, grain (barley) supplementation at a rate of around 400g/hd/day is recommended to reach optimal levels for growth (depending on the quality of the pasture). A support supplement like StockMins-Lamb Finisher, is specifically designed to boost lamb production on mature green pasture by increasing dietary protein, boosting feed conversion efficiency and safely supporting the consumption of mid-level grain diets.

Grazing Lucerne

When winter-dominant pastures begin to mature and decline in energy and protein, generally from late spring onwards, we are presented with the perfect time to graze lucerne. The high level of protein in lucerne makes it ideal for growing lambs, especially during summer when adequate protein sources are limited. However, lucerne, especially mature lucerne, is low in energy at around 10MJ/kg DM. Furthermore, with a crude protein level of around 28%, lucerne can be too rich in protein. In this case, the animal needs to expend energy in excreting residual protein, which can put further downward pressure on energy availability.

This energy shortfall can be corrected by offering grain (barley) at around 400g/hd/day, and when paired with StockMins-Lamb Finisher, producers have reported live weight gain in lambs at around 350g/hd/day.

A form of roughage (hay or straw) should also be provided free access when grazing lucerne to stimulate cud chewing, promote optimal rumen function and reduce the risk of ‘Red-gut’.

Boost Liveweight Gain with StockMins-Lamb Finisher

Whether grazing lucerne or mature pastures during summer, StockMins-Lamb Finisher is the ideal green feed supplement in grain-assisted grazing situations. A balanced combination of essential minerals, vitamins, trace elements and Bovatec® assists with the development of rapidly growing lambs. Additionally, StockMins-Lamb Finisher boosts protein for situations where it is limited and contains acid buffers to support mid-level grain supplementation.

StockMins-Lamb Finisher is built with Bovatec® to boost live weight gain and feed conversion efficiency in sheep. In fact, numerous studies have shown Bovatec to generate up to 14% extra growth in livestock grazing green feed.1

  1. Zoetis Data on File. ®Bovatec is a registered trademark of Zoetis.