Estimating required supplements for breeding ewes (NSW)
It is likely that at some stage during the breeding cycle the available pasture will not be sufficient to meet the energy requirements of your ewes. So you will need to supplementary feed your ewes to ensure they achieve the fat score targets.
The following tables were calculated by Doug Alcock (NSWDPI Livestock Officer, Cooma) using the commercially available GrazFeed program (Horizon Technology).
Step 1: Determine whether your ewes are in an energy deficit
Identify the livestock category and pasture characteristics that best match your current situation using Table 1.
If your ewes fall into one of the shaded boxes this indicates that their energy requirements are currently being met by your available pasture.
If your ewes fall into one of the boxes containing a number this indicates that your ewes are energy deficient at this time and will require supplementation to maintain their condition. The number indicates their likely energy deficiency.
For example a 50kg dry ewe running on 1500 kgDM/ha of 45% digestibility.
Step 2: Select an available feed
If for our example you have oats on hand in the silo of 11.4 MJ/kg.
Table 2. Likely dry matter (DM) and metabolisable energy (MJ/kg)
Step 3: Determine how much feed to offer
From Table 2 identify the dry matter and energy content per kilogram of your available feed.
For our example, the 50 kg dry ewe will need 7.1 MJ if pasture is 40% digestible and 5.4 at 50% digestibility. Therefore the extra energy requirements of our animal will lie between these figures, say 6.3 MJ.
To determine the feeding rate we need to determine how much of the oats are required to yield 6.3 MJ. If feeding oats of 11.4 M/D & 10% CP then 6.3 / 11.4 X 1000 = 552 g DM/day would be required.
Correcting for 90% DM then, 552 / 0.9 = 614 g/head/day, would be the as fed quantity of oats required for maintenance of this dry ewe.
For more information on feed budgeting for ewe flocks and Fat Score targets throughout pregnancy and lactation please talk to your local DPI officer.
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