Nutritional Management is the one of the most important management
items the shepherd should be concerned about. Ewes that are fed
well balanced diets are more fertile, milk better and wean more
lambs that grow faster. Not only do well fed ewes wean more pounds
of lamb per year, but they are healthier and more resistant to infections
and disease than ewes that are under Nutritional Stress. If you
are in the sheep business to make money, the Nutrition Management
of the ewe flock should be your number one concern.
Feed costs on the average sheep farm in Ontario accounts for approximately
80% of the Direct Farm Expenses. From the l986 Enterprise Analysis
Project, the average ewe (from 30 farmers, 5070 ewes), cost $62.48
to feed for a year. This represented 82% of the Direct Farm Expenses
and 50% of the Total Farm Expense. Feed costs are the single largest
expense on sheep farms in Ontario Therefore, it is imperative that
the flock owner evaluates the feed resources he or she has and manage
the feed resource to maintain good ewe nutrition and generate a
reasonable profit per ewe.
The most damaging disease in sheep flocks in Ontario is "Empty
Gut Disease". If "Empty Gut Disease" hits your flock
it will reduce profits to zero or lower. The cause of Empty Gut
Disease is inadequate intake of nutrients by the ewe. There are
five nutrients we supply to the flock they are: water, energy, protein,
vitamins and minerals. Most often, the limiting nutrient on most
farms is energy. Energy is supplied in the ration through the hay
and grain mix. Most cases of Empty Gut Disease occur when inadequate
amounts of concentrate (grain mix) is supplied to the flock. Empty
Gut Disease results from an inadequate evaluation of feed resources
and when body condition scoring is not performed. Empty Gut Disease
is the main reason for low profits in the sheep business.
In order to manage sheep easily, and according to their needs,
it is critical to know where in their production cycle, any given
group of ewes is at any given time, so they can be separated and
managed accordingly. Regardless of the production system a producer
is in (accelerated or once-a-year), the key to profitability is
feeding to production (and knowing what stage of production the
ewes you are feeding are in), and minimizing feed costs by avoiding
unnecessary extra feeding.
In a ewe's production cycle, we generally consider that there
are six (6) important stages of production: maintenance, flushing,
breeding, early gestation, late gestation, and early lactation.
Management in general, and nutritional management specifically,
must change for each of these stages if a producer is to have
a successful lamb crop and, more importantly, good returns for
lambs sent to market.
In terms of nutrition, requirements are least during maintenance
and early gestation; and greatest during late gestation and lactation
(especially for ewes carrying multiple fetuses and nursing twins
or more). The diagram below gives a good indication as to the
changes in nutrient requirements as a ewe goes through the various
stages of production.
Figure 1. Approximate daily digestible energy
(DE) requirements of 65 to 70 kg breeding ewes at various production
stages.
Text
explanation of Figure 1
Maintenance (0 to 16 weeks)
By this, we mean that the animal's only nutritional needs are
those to maintain desired body weight. No form of production is
occurring (i.e. the animal is not lactating, or pregnant). Requirements
for all other stages, therefore, must always be higher than that
for maintenance. Duration is dependant on production system; being
next to zero days in some accelerated lambing programs, and up
to 16 weeks in once a year lambing situations. Because ewes are
not only maintaining their weight, no grain feeding is required
during this period.
Breeding & Flushing
The practice of increasing nutrient intake and condition prior
to and during breeding is called flushing. Its purpose is to increase
the rate of ovulation and, hence, lambing rate. The response to
flushing is affected by the age of the ewe (mature ewes show a
greater response than yearlings), its breed, body condition, and
the stage of the breeding season. The greatest response is seen
early and late in the breeding season; with flushing during the
seasonal peak being least effective in increasing lambing percentage.
Flushing is especially beneficial for thin ewes that have not
recovered from previous lactation stress.
Flushing is generally accomplished by providing ewes with fresh
pasture, supplemental harvested forage, or up to one pound of
grain per ewe daily, depending on environmental stress (time of
year), availability of forage, and body condition of the ewes.
Special feeding usually begins around 2 weeks prior to breeding
and continues at least 2 to 4 weeks into the breeding season.
This ensures good embryo attachment to the uterus wall, reducing
early embryonic death. Flushing should not be continued too long,
because an extended period of high feeding is unnecessarily costly,
and overconditioning during pregnancy should be avoided, as should
be drastic or severe decreases in the level of nutrition. Typical
grain feeding would be in the range of ½ to 1 pound of
mixed grain per ewe per day.
Early Gestation (15 weeks)
In early pregnancy, fetal growth is very small, and the total
feed requirement of the ewe is not significantly different from
that during the mainentance period. Ewes can therefore be fed
a similar ration with a slight increase in the amount offered.
It is unusual that grain feeding is necessary during this time
unless forage is exceptionally poor and ewes are underconditioned.
Late Gestation (last 4 weeks)
Next to lactation, this period has the greatest nutrient demands
for fetal growth and the development of the potential for high
milk production. Over 80 percent of fetal growth occurs in the
last six weeks of pregnancy. Inadequate nutrition (especially
energy) during this time will have detrimental effects on milk
production of the ewe, birth weight of the lambs, and vigour (survivability)
of the lambs. Ewes should be fed at least 0.75 lbs of mixed grain
per ewe daily if lambing percentage is expected to be average
and up to 1.5 or 1.75 lbs of mixed grain per ewe daily to ewes
whose lambing percentage is expected to be above 200 percent.
Lactation (6 to 12 weeks)
Lactating ewes normally reach their peak in milk production around
3 to 4 weeks after lambing and produce 75 percent of their total
milk yield during the first 8 weeks of lactation (Boylan, 1984).
A ewe nursing twin lambs produces 20 to 40 percent more milk than
a ewe nursing one lamb.
Because lamb growth is of primary importance, and is dependant
on the milk production of the ewe, optimizing milk production
is critical. Too often, we see flocks where ewes are not being
fed high enough levels of feed for the number of lambs they are
nursing. In most cases, this usually entails not enough grain
being fed during the first 4 to 6 weeks of lactation (inadequate
energy, but often not enough protein as well). Milk production
in the ewe responds to nutrient intake just as it does in dairy
cattle.
With average to good quality hay, ewes nursing singles will need
about 1.5 lbs. of mixed grain per day; those nursing twins will
require 2 to 3 lbs. per day.
Accelerated Lambing
The above information deals with the stages of production assuming
once a year lambing, whether on grass or winter lambing. Producers
who are on an accelerated program will have to keep ewes in above
average body condition for it to be successful. Ewes should not
be allowed to lose too much body condition during lactation if
they are expected to rebreed, and perform well in terms of number
of lambs born, weaned, and weight of lambs weaned.
Ration Formulation
The Ontario Ministry of Agriculture and Food offers a Sheep Ration
Formulation Service. Rations can be balanced based on the feed
available on the farm, the mature body weight of the ewe being
kept, the expected lambing rate, stage of production (maintenance,
gestation, etc.) and body condition score. The Rations that are
formulated will provide suggested amounts of feed to supply to
the flock throughout the different stages of production.
Body Condition Scoring
The step to good flock nutrition that is most often over-looked
is Body Condition Scoring. The shepherd must condition score the
flock to determine how the ewes are responding to the nutritional
package supplied to them. If this step is not completed the entire
exercise of forage sampling and ration formulation is useless!
The Shepherd must assess how the flock is responding to the feed
provided to them. If body condition scoring is not done, good
flock nutrition will not be obtained.
Feeder Space
Adequate feeder space must be provided to the ewe flock. Sixteen
to eighteen inches of feeder space must be provided per ewe if
all the ewes are to eat at once. If this space is not supplied
the small and more productive ewe will lose body condition and
becomes less productive. Adequate feeder space will ensure that
all ewes will have equal opportunity to consume their daily ration.
Water
In many cases, water is the cheapest nutrient supplied to the
ewe flock. The flock should have available to them a fresh, clean
source of water, at all times. This is particularly important
for lactating ewes and young lambs. Lactating ewes require a lot
of water if they are going to milk well. Dry ewes require less
water than lactating ewes and water for dry ewes during the winter
can be supplied by snow if necessary. It is recommended that one
square foot of water surface be provided for every 40 ewes.
Ram Management
Another important thing that must be determined before the shepherd
can effectively manage the feed resources available, is the flock's
reproductive status. The shepherd can not effectively supply the
flock with the proper nutrition if the ewes are not at a similar
stage in the production cycle. For example: it is difficult to
meet the requirements of all the ewes in the flock when some ewes
are going to lamb in January and other ewes are not going to lamb
until April. The nutritional requirements are different depending
on the stage of production. To ensure that all ewes are at the
same stage of production, ram control is very important. A suggested
breeding schedule could be:
