1. Seasonality of reproduction in sheepZeleke MekuriawEIAR-DBARC-ICARDA-ILRI (LIVES)-FAO Training on Reproductionin Sheep and Goat, Debre Berhan, Ethiopia, 13-15 October 2014

2. Introduction Sheep in general are considered to be seasonal breeders Seasonality more pronounced in feral sheep Getting diminished in sheep kept under intensive management Photoperiod is a major cause of seasonality of reproductionsheep in temperate areas Other factors such as environmental temperature, feedavailability, social cues have effect on reproductive functions 3. Economic importance of seasonality of reproductionPositive: Improved survival of lambsNegative: Limits year round availability of lambs Prolongs lambing interval Prolongs age at first mating/lambing Reduces life time productivity 4. What induces seasonality of reproduction in sheep?Photoperiod: Important in temperate areas Less important in tropicsPineal gland: Transducer of photo stimuli to hormone Located in the brain It is a signal for season change 5. PhotoperiodMelatonin: Produced during dark hours of a day Induces seasonality of reproduction in sheep Affects both male and female reproduction More potent in female Long duration of melatonin secretion is stimulatory Short duration is inhibitory Melatonin is a signal to the neural structures controlling thesecretion of GnRH 6. What induces seasonality of reproduction in tropicalsheep?Feed availability: Availability of feed is seasonal in extensive managementsystem More feed during rainy season Sever shortage during dry season Poor quality during dry season Very poor body condition of ewes during dry season Most of the mating occur during rainy season (short and longrainy seasons) 7. Consequences of poor feeding managementFemale:Long term under feeding at early age has carryover effect at later stage Affects ovulation rate and twining Irreversible effectShort term effects Poor body condition inhibition of ovarian activity Embryonic mortality Silent heat 8. Consequences of poor feeding management Male: Reduction in testicular size Low semen volume Reduced libido Higher percentage of abnormal/deadspermatozoa 9. Consequences of poor feeding management Measures to be taken: Provision of adequate quality and quantity of feed yearround Supplementary feeding management for breeding stock Strategic feeding (flushing) prior to mating Periodic deworming 10. Ambient temperatureHigh ambient temperature Not significant for indigenous breeds May affect imported exotic breedsFemale embryonic mortality Short duration of heat Silent heat Prolonged oestrous cycle 11. Ambient temperatureMale More effect on quality of semen Reduced volume of semen Higher percentage of abnormal spermatozoa Higher percentage of dead spermatozoa Effect on libido Increased testicular temperature More sever in over conditioned rams 12. Ambient temperatureMeasures to be taken: Selection of adaptive breeds Provision of suitable microclimate Availing amble amount of water Maintaining normal body condition of breeding stock 13. Social cuesFemale: Introduction of rams to ewes provoke ovarian activity Ewes display signs of heat in the presence of ramsMale: Presence of female in heat provokes libido in male Improves semen volume and quality for AI Effect of early isolation of lambs from females on its sexualactivity at later age is not significant 14. Mating/lambing pattern of Ethiopian sheep breeds Literature is very scanty Few findings indicate more mating during rainyseason (short and long rainy seasons) Lambing often occurs during or the end of main rainyseason 15. Some information on reproductive performance of Ethiopiansheep breedsAge at 1st lambing and lambing interval 16. Some information on reproductive performance of Ethiopiansheep breedsLitter size 17. Some information on reproductive performance of Ethiopian sheepbreedsBW, Wt & ADG 18. Some information on reproductive performance of Ethiopiansheep breedsPre-weaning mortality 19. Sheep breeds and their distribution 20. Gaps to be filled!Conditions Reproductive performance GrowthperformanceImproved feeding ? ?Improved health care ? ?Housing ? ?Response to reproductivetechnologies? ? 21. www.lives-ethiopia.orgThe presentation has a Creative Commons licence. You are free to re-use or distribute this work, provided credit isgiven to ILRI.