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Lambing at the right time - the first step to increasing sheep profits

 
This work is based on the modeling work and report by Lisa Warn (principal author) and John Webb Ware, Mackinnon Project, University of Melbourne, Libby Salmon and John Donnelly, CSIRO Plant Industry and Doug Alcock, NSW DPI.

In southern Australia increasing the use of pasture grown is the most effective way to lift the productivity and profitability of most sheep enterprises. Selecting the right time of lambing, by matching the increased feed requirements of lambing ewes to the peak of pasture growth, is the first step to optimise pasture utilisation.

When is the right time to lamb?

Recent work by the Australian Sheep Industry Cooperative Research Centre has identified that the right time to lamb in southern Australia is related to the length of your growing season, but the exact timing will vary for different sheep enterprises. Guidelines are:

Flock type

Number of months before the end of the growing season to start lambing

(a) Self-replacing Merino flocks producing Merino lambs as replacements and selling surplus young sheep at 12 months or older

3 months

(b) Merino flocks producing 12-month-old Merino sheep for slaughter

3 months

(c) Flocks producing Merino or crossbred lambs for sale between the ages of 4 and 6 months.

4 months for light trade or store lambs

5 months for heavier lambs (supplementary feeding may be required)

There is no financial benefit in lambing earlier to produce heavier lambs. The costs are either a reduction in potential stocking rate or an increase in supplements fed to ewes if stocking rates are to be maintained. Either way, gross margins are reduced.

Optimising the amount of meat and wool produced per hectare, while minimising feed costs, is what drives income and profit; it does not come from receiving the highest price per kilogram or producing the heaviest lambs.

Selecting the right time of lambing allows you to increase stocking rate without increasing the risk of supplementary feeding the ewes. The economic benefit will be greater at higher stocking rates.

What are the risks associated with changing time of lambing?

If you are understocked, changing only the time of lambing will not produce a major improvement in pasture utilisation and profit. For example, if you are running Merino ewes at 4 ewes/hectare on well-fertilised improved pastures, and change from a May to an August lambing, you will only increase pasture utilisation from 21% to 22%. However, you will reduce the amount of supplements fed to ewes and increase gross margin slightly. By contrast, lambing in August and increasing stocking rate to 10 ewes/hectare would increase utilisation to 50% and more than double gross margin per hectare.

Good weaner management is critical. Changing from autumn to late-winter or spring lambing requires more skill than just putting the rams out later. Lambing later calls for improved weaner management, as later-born lambs will be lighter at the end of the growing season than earlier-born lambs. However, it is more cost effective to feed supplements to weaners over summer and autumn, than it is to feed pregnant or lactating ewes in autumn.

Tips for good weaner management?

Weaners that weigh 20 kg have less than 1 kg of fat reserves. If they lose any weight, they have a high probability of dying. Hence, weaners should be weighed over summer and autumn to check that they are growing. Some other tips for good weaner management are:

  • Wean 12 to 13 weeks after the start of lambing.
  • Ensure lambs reach the critical weaning weight of 45% of mature weight (e.g. 22 kg if mature sheep are 50 kg).
  • Select paddocks for weaning that have a low worm risk and good quality pasture (4 to 6 cm pasture lengths with 30 to 40% clovers).
  • Monitor weaner numbers and weights every 4 weeks; feed supplements if necessary to ensure weaners grow at more than 1kg per month.
  • Prepare additional paddocks with low worm contamination for the following winter.

What are the take home messages?

  • In southern Australia selecting the right time of lambing is the first step to optimise pasture utilisation.
  • Increasing the use of pasture grown is the most effective way to lift the productivity and profitability of most sheep enterprises.
  • The right time to lamb is related to the length of your growing season, but the exact timing will vary for different sheep enterprises.
    The economic benefit will be greater at higher stocking rates; if you are understocked, changing only the time of lambing will not lead to a major improvement in profit.
  • Good weaner management is critical to success.