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Reproduction
The major factor affecting
profitability of sheep operations is reproductive efficiency or
percent lamb crop raised and marketed. The gain in nutritional or
economic efficiency associated with an increased number or size of
lambs offers the greatest potential for increased profitability
due to the fact that 70% of the feed required to produce a weaned
lamb is consumed by the ewe. Ewe maintenance cost is reduced when
spread over more and/or larger lambs. Lamb production can be
improved by:
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Producing more lambs at each lambing
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Increasing lambing frequency
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Improving herd health
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Reducing parasite infestation
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Reducing lamb death loss
Reproductive Facts:
Puberty: Minimum range is 5-9
months at 70-100 lb. Puberty is influenced by breed, genetic
selection, body size, nutrition, and birth date.
Estrus Cycle: Ranges from 14
to 19 days, with average of 16.7 days. Estrus period is
approximately 24-36 hours; with ovulation occurring near the end
of the period.
Breeding Season:
Length of
daylight, breed, and age influence length of the breeding season.
The breeding season typically starts in the fall and lasts five to
seven months in common domestic sheep breeds. Going into the
breeding season, ewes should be in moderate body condition and
gaining weight.
Gestation: 142 to 152 days
(approximately five months). Well-developed and well-managed ewe
lambs may be bred to lamb as yearlings. Ewes must be thrifty and
healthy, but not fat. During the last six weeks of pregnancy, a
ewe should gain approximately 20 lb if carrying a single lamb and
30-35 lb if carrying twins or triplets. This gain will aid in
preventing pregnancy disease, ensure strong lambs, and improve
milk production and mothering instinct. The last six weeks of
gestation are especially critical in the nutrition of ewes.
Approximately 70% of fetal growth occurs during this period and
sufficient nutrition must be provided for this nutrient drain. If
nutrient restrictions occur, lighter lambs, increased post-natal
losses, reduced mothering instinct, lower levels of milk
production, and increased pregnancy disease will occur. When
trimming hoofs or shearing during the last month of gestation,
handle ewes gently.
Rams: To ensure a maximum lamb
crop, use the proper number of rams. Rams should be at least 10
months old before mating. To achieve optimum breeding performance,
rams should be subjected to a breeding soundness exam and should
be in moderate body condition. Rams are normally left with the
flock for an eight-week breeding season. Shearing rams prior to
the breeding season may be beneficial, especially during hot
weather. To facilitate breeding records, oil paint may be applied
to the ram?s brisket daily, which will identify ewes that have
been bred. Paint colors can be coordinated with first, second, and
third sections of the breeding season.
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