| | Feeding silage to sheep
Small flock owners most commonly use dry harvested forages - hays - for feeding their sheep flocks. Large flock operations, with access to specialized harvesting, storage and feeding equipment, are more likely to use fermented feeds - silage or haylage. Fermented feeds can lower crop harvest losses compared to leaves lost with haying. There can be more nutrients are preserved as well as more consistent forage quality over the feeding period than with hays. Less labour is required for mechanized harvesting and feeding. Silaging is somewhat less dependent on really good weather than are haying operations.
Almost any grain, legume, or forage grass can be ensiled and fermented. Silage usually refers to barley, oats and corn while haylage, or baleage, generally refers to hay crops that have been ensiled. As varieties change more corn is being used for silage. The whole corn plant is harvested at about 60-65% moisture with up to 50% dry matter in corn grain.
The maturity of the crop or forage should determine optimal harvest date. With grasses and legumes cutting early preserves quality. The moisture content also plays a role in the quality of fermented feeds, high moisture silage is over 70% moisture; low moisture haylage can be 40% to 50% moisture.
The high moisture content of some silages and baleages can lead to decreased feed intake. For young animals and ewes in late pregnancy feed intake is a concern. Properly balanced rations with added supplements reduce intake problems. Another concern for sheep producers is the risk of listeriosis.
Listeriosis
Listeriosis or “circling disease” is caused by the bacterium Listeriosis monocytogenes. It affects both animals and man. Listeria are naturally present in the soil and thrive in cool moist conditions. The bacteria grow in spoiled fermented feeds and wet hays. Silage making should minimize contamination of the forage with soil. To grow in silage, the bacteria require oxygen and a pH above 5.5. Listeria grows in silages wherever there is an infiltration of oxygen, such as the open end of the bag or around a hole in a silage bag. Spoilage also occurs at the edges and "face" of the silage pit, on the top layer of silage in an upright silo, on the exposed or open “face” of haylage bales and also in left-over feed in feed bunks. Sheep should clean up all the silage in the bunks at least every twenty-four hours. The major source of listeria in sheep comes from eating poorly fermented, or mouldy, silage. The incubation period between eating the silage and coming down with listeriosis is about three weeks - the problem silage may be long gone.
In sheep, listeria may cause abortion in late pregnancy, generalized infection (septicemia), inflammation of the brain (encephalitis) and death in newborn lambs. Clinical symptoms of the disease can occur in sheep of any age approximately three weeks after ingestion of the feed containing the bacteria. Not all sheep exposed to the bacteria get the disease. Symptoms include depression, facial paralysis, blindness, walking in circles and death. There is no proven effective treatment for listeriosis. Proper silage making and good feeding management reduce the risk of this disease.
Preventing listeriosis
- Ensile at 30-50% Dry Matter (DM).
- Pack silage well.
- Seal pits and bags well.
- Ferment silage for 3 to 4 weeks before feeding.
- Check silage bags frequently for holes and seal promptly.
- Wait for three weeks after silaging before feeding. Start slowly and gradually increase amount of silage.
- Do not feed mouldy or spoiled silage to sheep.
- Clean up spilled silage around feeding areas.
- Clean feed troughs daily and do not throw spoiled silage into the pens. Spoiled silage can contaminate fresh silage.
- Feed only what the sheep will clean up daily.
- The disease is contagious to humans, practice cleanliness and care when handling sick animals.
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Silage feed intake
One of the major drawbacks to fermented feeds is that animals generally consume less of them than they will similar quality dry forage. Even when accustomed to eating silage, some sheep will not consume enough silage to achieve adequate nutrient intakes. The decrease in feed intake is related to the various compounds produced when the silage is broken down in the rumen (digestion stomach). In addition, high ammonia and butyric acid levels in silages containing greater than 66% moisture can cause depressed feed intakes.
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Increasing silage intake
- Chop forage uniformly (1 inch in length for cereals and 1/4 to 1/2 inch for corn).
- Introduce silage gradually to allow the sheep to adapt to its taste.
- Feed silage more often (two to three times daily).
- Provide plenty of feeder space.
- Allow plenty of fresh clean water.
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Feeding silage to mature sheep
Table 1. Daily nutrient requirements of a 154 lb. ewe
Production
Stage | Estimated
DM Intake
(kg) | DE
(Mcal/day) | Crude
Protein
(kg) | Ca
(kg) | Phos
(kg) |
Gestation
1st 15
weeks | 1.5 | 3.7 | 0.145 | 0.005 | 0.003 |
Gestation
last 6
weeks | 1.9 | 6.0 | 0.236 | 0.010 | 0.007 |
Lactation
Single
Lamb | 2.5 | 7.7 | 0.340 | 0.011 | 0.008 |
Lactation
Twin
Lambs | 2.8 | 8.8 | 0.454 | 0.013 | 0.010 |
Adapted from 1985 Nutrient Requirements for Sheep
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Key ideas
High quality ensiled feeds can be fed to sheep at each stage of production providing the sheep:
- consume enough dry matter
- meet their daily nutrient requirements
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The results of a feed test for barley silage show that on a dry matter (DM) basis, the silage sample contains 35.6% DM, 11.4% crude protein, 2.20 Mcal/kg of digestible energy (DE), 0.62% calcium and 0.28% phosphorous. If a 154-pound ewe were fed 5.1 kg per day of this silage during early gestation, she would be eating 1.82 kg of dry matter. This amount of silage would provide her with 4.0 Mcal of DE, 0.21 kg of protein, 0.011 kg of calcium and 0.005 kg of phosphorous. Comparing her nutrient intake to the requirements given in Table 1, the silage would provide more than adequate nutrition for the ewe in early gestation.
However, during the last six weeks of pregnancy and during lactation, even for a ewe nursing one lamb, the ewe’s nutritional requirements cannot be met by feeding only the silage. Additional protein, energy and minerals need to be supplied, preferably in the form of high quality hay and grain. If high quality legume hay cannot be supplied, then protein supplementation will be necessary as a part of the grain mix.
Feeding silage to lambs
It is well known that in order to achieve acceptable growth rates lambs require high-energy diets. Feeding silage as the sole feed to lambs weighing less than 40 lbs. can result in starvation because they physically cannot consume enough DM to meet their nutritional needs. Once lambs weigh over 65 pounds, a silage concentrate ration will support acceptable growth rates. Energy, protein, mineral and vitamin supplementation will be necessary for lambs fed silage. However low nutrient content silage, made from mature forage or excessively wet forage should not be fed to lambs. Each producer will need to evaluate the economics of feeding silage with supplementation verses feeding a hay-grain diet.
Feeding silage to dairy sheep
For dairy sheep operations, it is also important to realize that silage-fed animals are more apt to shed Listeria monocytogenes in their feces and milk than are hay-fed sheep. Before using silage in dairy sheep rations, producers need to discuss the feed cost advantage and potential risks with both veterinary practitioner and cheese plant manager.
References
Gates, N. 1994. A Practical Guide to Sheep Disease Management. News-review Publishing Co. Moscow, Idaho Pg 95-97.
Feeding Corn Silage to Sheep, Wand and Topp; Agdex #430/61 June 2014 (see pdf) http://www.omafra.gov.on.ca/english/livestock/sheep/facts/14-021.htm
For more information: "Sheep and Goat Management in Alberta - Nutrition" (see pdf) http://www.ablamb.ca/index.php/resources/management-modules
Sheep Nutrition Questions? Contact: Alberta Ag-Info Centre at 310-FARM (3276)
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