The break of season is a crucial time for many ewe flocks on annual pastures as the quality and quantity of dry feed is very low and the emerging green feed will usually need to be supplemented to meet animal energy requirements. Pasture is growing very quickly and growth rates can change over night due to soil moisture and temperature.
It is also important that the amount of pasture available is estimated correctly as emerging annual pasture can be deceptive in its quantity. Refer to the pasture photos in the tools for managment section to check your estimates. The feed intake levels form pastures at this time is higher than for the same amount of pasture in the spring time. This is due to the upright nature and the ease of access to the sheep. Once clover pastures are tightly grazed in winter and spring it will require at least double to amount of FOO to maintain a sheep.
The general steps for feed budgeting at any time of the year are;
1. What they can eat - What they require = surplus or deficit of energy
2. If they aren't getting enough energy then how much to feed to meet the requirement.
It is important to remember too, that the energy requirements of sheep vary with the feed they are eating, the amount of grazing they are doing to find the feed and their current status of nutrition and whether they are dry, pregnant or lactating.
The tables presented below are general values only. It is important that these are used only as a guide and that regular condition scoring of the flock is the best way to tell if the feeding rates are adequate for their needs.
Step 1. What they Need
Using either Table 1a. or 1b. select the column for the frame size and row for the pregnancy status of the flock, finding the value for maintenance energy required in MJ/day.
These values will vary slightly depending on the quality of paddock feed and supplement the ewes are eating as well as the weather conditions and terrain of the paddock and the age of the ewe (this table assumes ewes have an average diet of 12MJ/h/d and are on sloping terrain with 20% sub clover in the pasture. For other situations please refer to Grazfeed).
Example: medium frame ewes at condition score 3 with twins at day 100 of pregnancy need approximately 11.5 MJ/day to maintain their condition.
Step 2. What they can eat
Using Table 2 a, b or c identify the estimated metabolisable energy (MJ) intake from GREEN paddock feed. Use Table 2a for small frame merinos and Table 2b for medium frame merinos and Table 2c for large fram merinos. Please note that these intake figures will change for spring pastures or those in the vegetative phase (see pasture assessment for more details).
Example: The ewes in step 1. are grazing pastures of green 500 FOO(kgDM/ha). This means they can eat approximately 9.5 MJ/day.
Step 3. Losing or Gaining Weight?
This is calculated by subtracting the results of Step 1 from the results of Step 2, that is, what they can eat minus what they need. This is then either a surplus and ewes will increase in condition, or a deficit and ewes will lose condition. Table 3 shows the deficit or surplus in terms of grams per head per day and in change in condition score in 30 days for each frame size.
Example: The ewes from Step 1 (need 11.5MJ/d) and Step 2 (can eat 9.5 MJ/d) have a deficit of 2MJ/d (11.5 -9.5MJ). This means the ewes will be losing about 70gms per head per day or 0.3 of a condition score over a month. This is close to the recommended weight loss allowed for pregnant ewes until day 90. At day 100 it is recommended that the ewes be gaining on green feed. This would require at least 900 FOO with 1500 FOO by lambing (see guidelines for WA and SA).
Step 4 How much to feed?
Use the Table below (from Managing Sheep in Dry Times Bulletin DAFWA) to obtain an estimate of the energy value of the feed expected to be fed. We suggest that feeds are tested as they can be variable, especially hays and silage.
Step 5: Determine how much feed to offer
Once a target condition for the ewe flock and how much energy is required to meet that target been decided, and the energy value of the feedstuff determined you need to calculate how much feed to offer.
Ewes in energy deficit:
Use the table below: use the 1st column to identify the quality of the feed (13 MJ/kg), read across until the approximate deficit amount is found (2MJ), then follow the column upwards to read off the feeding rate (0.2kg).
Divide the deficit (MJ/day) by the energy value of the feed (MJ/kg). This gives the number of kilograms per day to be fed.
For example if ewes need 2MJ/d. Using barley at 13MJ/kg they require 2/13 = 0.154kg of barley
These figures are expressed in dry matter per kilogram so it is important to convert the amount to 'as fed' kilograms which takes into account the moisture content of the feed.
To do this; Divide the kg/head/day to be fed by the dry matter % from Table 4. This is the weight to be fed out in the paddock.
barley at 90% Dry Matter and 0.100kg/hd/d required:
0.154kg / 0.90 = 0.170kg to be fed.