Diet Supplementation for Grazing and Outwintering Ewes
|Last Reviewed:||10 février 2010|
|Written by:||Christoph Wand - Beef Cattle, Sheep and Goat Nutritionist/OMAFRA|
Table of Contents
- Why Supplement the Diet for Ewes?
- Challenges and Limitations in Supplementing Diets
- Trough-free Feed Supplementation
- Methods of Delivery
- Diets for Outdoor Supplementation
Although adequate nourishment of the ewe flock begins with proper forage and pasture management, there may be specific occasions where, for a variety of reasons, it is useful to add a supplement to ewes' diet. Some examples are:
- Flushing - to increase the number of lambs born per lambing as a function of fertility at breeding. Supplemental protein, energy and minerals can increase the number of viable embryos from a mating.
- Out-of-season breeding - using compounds such as melengesterol acetate (MGA) in flushing rations can help improve out-of-season breeding success. The fertility that results when MGA is removed from the ration can be utilized to synchronize the breeding of groups of ewes. This technology requires consultation with and a prescription from your flock veterinarian.
- Lactating ewes - may need supplemental energy to support the demands of lactation. Especially in dairy and accelerated/prolific systems, energy and minerals may need to be supplemented above the level found even in good pastures.
- Pharmaceuticals - supplements can be an ideal method to deliver therapeutic compounds as well as preventative measures such as coccidiostats.
- Replacement ewe lambs - may require a small amount of supplemental protein, energy and minerals to ensure proper development both post-weaning and in late gestation.
- Gestating ewes - prolific ewes may require some supplemental energy, protein and minerals as well as a coccidiostat to ensure fetal development, newborn lamb vigour and adequate colostrum volume and quality.
Once the commitment is made to begin a supplementation program outdoors, the difficulties begin in determining the feasibility of delivering the appropriate supplement. Many producers have experimented with using lightweight mangers and pailing grain. Although that particular strategy may be successful for a small group of animals over the short term, the labour and physical risk to the shepherd involved usually hinder the success and life span of this practice in larger animal groups. There are ways to supplement ewes that are easier and faster than pailing grain into mangers on pasture!
Trough-free Feed Supplementation
An often overlooked fact in the effort to provide supplemental feed is that, because of their mouth structure, sheep can retrieve feed particles from within the pasture sward or off the sod. Provided feed is delivered on a clean surface (clean grass, sod or snow) and it is whole grains or pelleted, ewes very quickly learn how to thoroughly clean up supplement. The bottom line is that provided the diet is presented in a coarse format, pastured and wintering ewes can be fed directly on a clean ground surface (Figure 1).
Figure 1.Ewes can be fed directly on clean ground if the diet is in a coarse format.
Methods of Delivery
The simplest method of feed delivery is pouring pails of the supplement on the ground. However, when the feeding area is constantly moved the rate of flow is difficult to calibrate and manage. Thus, regulating the amount of feed in front of any given ewe, as well as ensuring appropriate 'bunk space' per ewe, may be difficult.
Mobile gravity flow hopper and chutes
These are bins with a controlled opening that allow the feed to slide out at a rate that can be pre-set. There are various designs that use flexible pipes to flow the feed, or the feed can fall directly from the opening. Typically they are homemade and are mounted on or pulled behind all-terrain vehicles (ATVs), tractors and other vehicles as trailers or sleds. The distribution of feed is in a continuous line from where feeding begins, which creates a risk of the ewes fouling the feed as they line up to eat.
Mobile dispenser units (snackers, snack wagons)*
These are a more advanced mobile unit that dispenses feed in discrete piles around which ewes form circles, which prevents the fouling of the supplement. Most typically, they use a wheel principle, where the predetermined amount is dropped at the rate of 1 pile per revolution. Ideally, the tire circumference allows 2 ewe lengths between piles.
A low cost version of a mobile dispenser unit uses a large tire that has solid sides, and 1 hole in its circumference fitted with a PVC or steel elbow. The elbow fills as the wheel turns and dispenses the feed once per revolution. The size of the elbow determines the amount of feed dropped per turn.
At least one manufacturer in Ontario has commercially available a snack wagon with a wheel driven drum that can be calibrated to drop varying loads per revolution. The feed is loaded into a hopper, and dispensed by the revolving drum, and can be pulled by an ATV or larger vehicle (Figure 2).
*Note: The information regarding mobile dispenser units is included for the convenience of flock owners. Inclusion of this information is not an endorsement of the products by the Ontario Ministry of Agriculture and Food.
Diets for Outdoor Supplementation
The larger the particle, the better the retrieval by sheep from amongst the pasture plants. As sheep ruminate (regurgitate and chew) whole cereal grains and corn, these work well in supplements, and, in fact, slow the release of energy. While pelleted diets can be used, pellets contain processed feed and are susceptible to wet conditions. However, pellets are the only way to deliver minerals, pharmaceuticals and any other granular material in this fashion. Suitable feeds for ground feeding include: whole shelled corn, any whole cereal grain, whole soybeans (raw and roasted), pellets (as large as possible) and any other nutritious feed that has the physical parameters to withstand the delivery tool, as well as ground contact outdoors.
Figure 2. A "Snack Wagon" supplementing outwintering ewes.
Although good forage management, including pasture, should be the cornerstone of the flock nutrition program, specific production issues may require supplementation of various nutrients. Supplements can effectively be fed on clean pasture, sod or snow. The delivery of this feed can be done using equipment in a range of sophistication, from pails to specially designed machines. Regardless of the method chosen, the diet utilized must withstand the requirements of such a program so that the retrieval of the supplement is maximized. As a result, whole grains and pellets are recommended for outdoor supplementation on the ground or snow.
For more information:
Toll Free: 1-877-424-1300