Reproduction

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
• gt 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
• _at_ 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
• 150 77 58
• 1200 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???