Diet Supplementation for Grazing
and Outwintering Ewes
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
- Conclusion
Why Supplement the Diet for
Ewes?
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.
Challenges and Limitations in Supplementing Diets
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
Pails
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.
Conclusion
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.
