| | Sheep producers sometimes consider feeding non-typical sheep feed - canola greenfeed, grass straws, poplar saplings, even poplar shavings. Odd and unusual rations need to be used carefully when wintering a breeding ewe flock. Some will work, others will not. The savings in feed dollars can be costly in production and animal health losses.
What nutrients are in the feed?
Always test feeds, particularly forages. Use feed test results to build rations. Provide supplements to make up for any shortages or for missing nutrients. A ration that is short on energy, protein, calcium or vitamin A can result in serious losses in late pregnancy and at lambing.
What are some of the factors that affect how much sheep will eat? After sampling and testing a feed, you need to consider whether or not your sheep will be able to eat it. Will they be able to eat enough of it to get the nutrients from it they require for their own health and for reproduction?
The two most important factors determining forage quality are digestibility and intake.
To estimate digestibility the feed analysis measures ADF (acid detergent fibre). To estimate intake the feed analysis measures NDF (neutral detergent fibre). The Relative Feed Value (RFV) is calculated using both the ADF and NDF values. If that's 'all Greek' to you, get help deciphering and translating your feed test results.
Keep in mind, the higher the quality of the feed, the less space it takes, the more the sheep can eat. Low quality and high fibre forages, straws and some greenfeeds take up more stomach space. Sheep will not eat more if their 'gut' is full.
Sheep can waste forages fairly effectively, even with good feeders. Sometimes a lot of feed waste isn't the sheep, or the feeder design, but the poor quality of the forage.
Another factor that affects how much a sheep will eat is the size of the feed 'particles'. Sheep ruminate (chew their cud) to break feed into smaller particles. When the particles are small enough, the feed will move from the rumen, to the lower digestive tract for digestion and then, finally, out onto the ground.
Low quality feeds require more rumination and are digested more slowly than high quality feeds. This slows down feed intake. Some feeds just take up too much stomach room and offer too little nutrients to sustain a pregnant ewe. Impaction results when feed stops moving completely - a serious situation for a ruminant.
Grinding and pelleting of forages reduces the amount of cud-chewing necessary and speeds the movement of the feed through the rumen, which increases the intake of feed. This processing of high fibre forages allows for blending of various quality forages and concentrates into a total mixed ration (TMR). Grinding feeds too finely, however, will reduce intake. Finely ground feeds can be dusty and there is an increased risk of bloat and impaction (of the omasum) on too finely ground feeds. Coughing, runny eyes and runny noses can also be a problem. Grains fed to mature sheep should be left whole.
Other factors affecting feed intake are:
- Mouldy feed and unpalatable feed (doesn't taste good) reduce the amount of feed sheep will eat.
- Silages with a high percentage of water, which takes up rumen space, will be consumed less. The drier the silage the more will be eaten.
- Forage consumption declines when supplemental grain is fed.
- Consumption of forage is affected by what is out in the pasture to eat. In over-grazed pastures sheep will spend much of their day grazing to try to fill their stomachs.
- Pregnant ewes will consume less forage - they have less space in their rumens.
- Consumption of forage will also be reduced if there is inadequate bunk/feeder space.
- Hot weather or lack of water decrease feed intake.
- Feed intake decreases when animals are sick.
- Age and body size requirements are different. There are big differences in the amounts of feed a Suffolk ewe and a Romanov ewe lamb can eat.
Talk to a feed company nutritionist if you get a feed test analysis back that you can't read - don't spend money on a feed test and not be able to read it and use it. For example, if the crude fat on canola screenings is 16% it tells you that you need to dilute the feed so the rumen doesn't shut down from too much fat. If the test comes back with high levels of potassium, it may signal that your ewes run the risk of winter tetany if you don't supplement the magnesium in the diet.
A feed test analysis provides a lot of information - be sure you don't miss any of it. Work with your feed company nutritionist if in doubt about feeds and rations.
For more information contact the Ag-Info Centre:
Toll-free in Alberta: 310-FARM (310-3276)
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