Learning Reproduction in Farm Animals

11-Effects of Environment on Reproduction


Learning Objective

Effects of environment on the female:

Photoperiod:

Adapted from Karsch et al. 1984. Rec. Prog. Horm. Res. 40:185

Regulation of Seasonality by Light

1.

2.

3.

4.

5.

6.
 

Seasonal Control of Reproduction in the Ewe

 
 

Out of Season Breeding (Hormone Induction)

  1. Progesterone and PMSG or P.G. 600

  2.  
    1. Implant Norgestomet implant (via ear) for 9 days

    2.  
    3. Inject ewes I.M. with PMSG (500 IU) or P.G. 600 at time of implant removal.

    4.  
       
  3. Melatonin
    1. Implants of Melatonin placed subcutaneously in the ear will provide continuous levels for 1 month
    2. Ewes cycle earlier and breeding season will also be longer

    3.  

Temperature Effects on Female:

Learning Objectives

Environmental Factors:
  1. Photoperiod
  2. Temperature
  3. Humidity or moisture
Photoperiod:
  1. Short day breeders
  2. Hormone Levels

  3.  
      Testicular tone:

      Seconday sex characteristics:
       
       

       

  4. Long day breeders:
    1.  
      Mounting Behavior and Reaction Time

      Effect of Day Length on Semen Quality

 
Best 
Worst
Ejaculate volume 
Feb - July
Sept - Jan
Sperm concentration 
Feb - July 
June - Jan
Sperm/ejaculate 
Feb - May
July - Dec
Sperm motility 
Jan - Aug
Sept - Oct
Mounts/ejaculate 
May - Aug (least)
Oct - Feb (most)
Reaction time 
Apr - Sept 
(shortest)
Oct - March 
(longest)
 

Illustrated Notes

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