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Reproduction

Reproduction. Sheep are seasonal polyestrous rams and ewes fall breeders day length cool temperatures ? continuous short days Impact on industry ??. Reproductive facts. Ewes Gestation length 143 -147 days Estrous cycle 16-17 days Estrus 12-30 hrs

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Reproduction

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  1. Reproduction Sheep are seasonal polyestrous rams and ewes fall breeders day length cool temperatures ? continuous short days Impact on industry ??

  2. Reproductive facts Ewes Gestation length 143 -147 days Estrous cycle 16-17 days Estrus 12-30 hrs Ovulation near end of estrus Puberty 6-18 months

  3. Hormones Melatonin - Pineal Gland Progesterone - Corpus Luteum Estrogen - Follicles GNRH - Hypothalamus FSH & LH - Anterior Pituitary Prolactin - Anterior Pituitary Prostaglandin - Uterus

  4. Stages of Estrous Cycle Estrus Postestrus Diestrus Proestrus Estrus ect.

  5. Rams Testosterone - Leydig Cells Temperature Regulation 5-7° below body T of 102° > 99° Problems Cremaster Tunica Dartos Pampiniform Plexus

  6. Rams Epididymis - four functions Transport Concentration Maturation Storage

  7. Breeding Capacity Spermatogenesis - 42 days 1 billion sperm per cc Each Ejaculate - .5 - 1.5 cc 5.5 billion sperm produced per day

  8. Tremendous Variation in Libido Duds and Studs, US Sheep Station 38% Rated as Low Performers @ 10% Showed no interest in Ewes 28% of unexposed ram lambs are inactive Environmental Temperatures above 770

  9. Ram : Ewe ratios Varies from 1-25 to 1-200 First service conception High Medium 1:50 77 58 1:200 50 33 More estrus ewes = more services 6-20/day

  10. Ram staying power 20 ejaculates per day for 20 days did not deplete semen concentration below acceptable levels

  11. Multiple Sire Mating Groups Dominant ram - Harem Subordinates - In and Outers Why Increase Mating Activity Goal: minimum of 3 services/ewe

  12. Physically Fit Rams exercised 1.8 miles per day for 40 days pre-breeding Increased lambs born by 10%

  13. Sheep Flock Math % ewes lambing of ewes exposed Lambs born per ewe lambing Lambs born per ewe exposed Lamb survival birth to weaning Pounds weaned/ee

  14. Reproductive efficiency Critical to flock profit Genetics or management???

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