A lambing system concerns when lambing will occur (what season
or months), how often a ewe will lamb (annual vs. accelerated),
and how and where lambing will occur (shed vs. pasture). There
is no one "best" lambing system or way to raise lambs.
Producers need to match the lambing system to their goals and
objectives, resources, and market demand. The same farm or ranch may utliize different lambing systems for different groups of sheep.
Early vs. Late Lambing
The first decision to make is when to lamb. There are pros and cons associated with lambing at different times of
Early Lambing (winter-early spring)
Early lambing systems have several advantages. High on the list
is labor availability. For producers who farm full-time, the
winter may be a time when labor is more readily available versus the
spring when field work and planting begins. Lambs born early in
the year are usually gone by the time summer comes, which frees labor for other farming operations.
Another advantage is marketing. Historically, lamb prices have
been highest during the first half of the year, especially during
the Easter season. As a result, lambs born in the winter were usually
sold for higher prices than those born in the spring. In more recent years, population demographics have altered the demand for lamb. Very often, the highest lamb prices of the year occur slightly before the Muslim Festival of the Sacrifice. This holiday moves 11 days forward each year.
who lamb in the winter can usually carry more ewes on their pastures,
since ewe feed requirements are only maintenance and lambs are
not competing for a possibly limiting resource, pasture.
If lambing occurs during the winter months, good
facilities are needed. Housing is a big consideration. Overhead costs are higher with winter lambing . Mastitis, scours, and pneumonia can be bigger issues
with early lambing because sheep are confined into smaller areas.
Early-born lambs are often creep fed and finished on concentrate
rations. They usually grow faster than those born later in the
year, but their cost of gain is usually higher. If winter-born lambs are put to pasture, they usually have less parasite problems compared to lambs born later in the spring.
Late Lambing (April-May)
Late lambing has many advantages over early lambing and is gaining
in popularity. With spring lambing, the sheep production cycle
is synchronized with the forage production cycle, allowing for
maximum use of forage resources. Late lambing takes optimal
advantage of the spring flush of grass. For most of the winter, ewes can be maintained on a maintenance
diet of relatively inexpensive hay or silage.
Spring lambing coincides with the natural breeding and lambing
seasons. With spring lambing, breeding and lambing periods tend
to be more condensed, because ewes and rams are most fertile
during a fall mating season. Most ewes conceive during their
first heat cycle and almost all will settle within two heat cycles,
resulting in a short 35-day lambing period.
Another advantage is that ewes usually give birth to larger
lamb crops. Even the breeds noted for out-of-season lambing
will produce a 10 to 20 percent higher lamb crop in the spring
than in the fall. Any breed of sheep can be raised in a late-lambing
The primary benefit to late lambing is reduced production costs:
lower feed costs, less labor, and overhead. However, late lambing
requires better pasture management than early lambing, since
lambs are usually fed or finished on grass. Internal parasites
and predators can be a significantly larger problem with late
Early spring and late summer conditions are the worst for parasite
infestations. Highest predation typically occurs from late spring
through September-October, as most predator species have pups or kits to feed. It is essential that producers have a plans
for dealing with both potential problems.
Fall Lambing (September-November)
Fall lambing has several advantages over the previous systems.
Late-gestation and lactation coincide with fall forage growth.
Weather conditions are usually ideal for pasture lambing. There
are fewer problems with parasites and predators with fall lambing.
Lambs can usually be sold when prices are the highest, around Christmas time.
However, fall lambing is a challenge because conception rates
are much lower than with spring breeding. Less seasonal breeds
are usually favored in a fall lambing program, although seasonal
breeds can be primed to lamb in the fall using the ram effect,
light control, and/or hormonal manipulation of the reproductive
From an industry standpoint, if more lambs were born in the
fall, the supply of lamb would be more even distributed, resulting
in more stable prices and steadier demand.
Acclerated lambing is when ewes lamb more frequently than once
a year. The purpose of accelerated lambing systems is to reduce
fixed costs, produce a more uniform supply of lamb throughout
the year, and increase profitability. There are several accelerated
Twice a year lambing
The most intensive form of accelerated lambing is twice a year
lambing whereby a ewe would produce two lamb crops per year.
Twice a year lambing has the potential to maximize lamb production,
but may not be practical under most commercial situations. Twice a year lambing is probably most common near the equator.
Opportunistic lambing is when rams are kept with the flock on
a continuous basis. With the right kind of ewes, this will result
in a lambing interval of less than 12 months. The problem with
opportunistic lambing is you don't know when lambs are due,
so the timing of vaccinations, deworming, and supplemental feeding
is more difficult. Lambs may also be born forage resources are poor. Keeping the ram with the flock all the time also increases the probablity of inbreeding, if female progeny are not removed in a timely fashion.
Three lamb crops in two years
The most common system of accelerated lambing is three lamb
crops in two years, resulting in an average lambing interval
of 8 months or 1.5 lambings per ewe per year. The 3/2 system
is usually characterized by a fixed mating and lambing schedule,
such as May mating/October lambing, January mating/June lambing,
and September mating/February lambing (or slight variations).
Another option is an 8 month overlapping system in which two groups of ewes lamb every eight months, but there are six lambing periods per year.
The STAR© system (five lamb crops in three years)
The STAR© system was developed at Cornell University. The
STAR© system is designed so that ewes produce five lamb crops in three years. The
calendar year is divided into five segments (the points of a star)
that represent one-fifth of a year or 73 days. Two fifths of a
year is 146 days, which is approximately the gestation length
of a ewe.
There are five lambing periods each year. Three groups of sheep
are managed separately: 1) breeding and pregnant ewes and rams;
2) lambing and lactating ewes and lambs; and 3) growing lambs
(market lambs and replacements). If a ewe misses a breeding, she
can still lamb three times in two years.
The STAR system is a natural system that does not use hormones
or light control to achieve out-of-season breeding. It involves
selecting sheep that breed during any season. The Cornell Dorset
flock, which has been on the STAR system for more than 15 years,
averages 1.5 lambings per ewe per year.
To be successful, accelerated lambing requires the right sheep
and careful management. Ewes and rams must be capable of breeding
year-round. Less seasonal breeds, such as the Dorset, Merino,
Finnsheep, Barbados Blackbelly, Polypay, Katahdin, St. Croix,
Romanov, and Rambouillet, are best suited to accelerated lambing systems.
The economics of accelerated lambing must be carefully examined.
The increased income from the sale of lambs needs to compensate
for the added costs and labor inputs. In addition, accelerated
lambing requires a much higher level of management.
Shed vs. Pasture/Range Lambing
Shed lambing is when lambing occurs indoors. Pasture lambing
occurs outdoors. Shed lambing is the most common system of lambing.
Even producers who raise their sheep predominantly on pasture
or range usually bring their ewes in for lambing. However, pasture
lambing is increasing in popularity due to the emphasis on more
sustainable systems of livestock production that require less
physical inputs, including labor.
Shed lambing provides the ewe and lamb(s) protection from the
elements, as well as predators. It allows for earlier lambing.
The primary disadvantge to shed lambing is cost. In addition to
the cost of lambing facilities, labor and feed costs are usually
higher. Due to the higher cost, shed lambing is most advantageous
for highly productive flocks. The shepherd has more control with
a shed lambing system.
Pasture (or range) lambing is becoming more popular. It is more natural and generally healthier
for the ewe and her lambs. However, it must occur during periods
of mild weather or lamb losses can be sustantial. Predation
can also be a more significant problem where pasture lambing
is practiced. Feed costs tend to be lower with pasture lambing
because ewes and lambs are getting most of their nutrient requirements
from pasture. Labor inputs are less because ewes are lambing
on their own.
Range lambing does not usuallly begin until mid-May when the risk of inclement weather has passed. Lambing is usualy unassisted. Lambs are marked (docked and castrated) all at once, usually before they are 60 days of age. Lambing occurs in pastures that are close to the homestead. Sometimes, the first-time lambers in range flocks are shed lambed.
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