Improving reproductive efficiency
Background to improving reproductive efficiency
Reproduction efficiency of sheep is measured by fertility rate (% ewes lambing per ewe exposed to rams/artificially inseminated) and prolificacy (the number of lambs born per ewe lambing). The economic relevance of the two parameters depends on the production system: fertility is more important than prolificacy in dairy systems, but not in meat systems. Acceptable fertility rates are around 90% whereas prolificacy depends on breed. Within breed, reproduction efficiency can vary widely, with fertility rates lower than 70% and prolificacy equal to 1 lamb per ewe lambing in some systems, but with the best flocks reaching 95-100% fertility and 1.3-1.5 lambs per ewe in non-prolific breeds and 1.8 to 2.5 in prolific breeds.
Ewes may fail to become pregnant because they are not mated or because they are unable to conceive after mating or AI. In addition, ewes may not maintain the pregnancy or lose some or all of their fetuses during pregnancy. A ewe may not be mated because she is not in the right condition to breed (e.g. due to ill health or age), because she is not cycling, or because the ram is not able to serve the ewe (e.g. due to ill health, libido or too many ewes). Ewes may not conceive because of poor egg or semen quality, stress (e.g. heat or handling), or pathology. Poor prolificacy in ewes can occur because of insufficient energy in the diet at breeding, poor body condition score, age, early embryo death or poor management of AI.
Each farm or flock may have different risk factors and prevalence for different causes of low fertility. Identifying the main reasons and risk factors for infertility are key steps in developing mitigation strategies. Recording fertility data and identifying when and why sheep do not lamb will help to improve reproduction efficiency.
Reproduction efficiency of sheep is measured by fertility rate (% ewes lambing per ewe exposed to rams/artificially inseminated) and prolificacy (the number of lambs born per ewe lambing). The economic relevance of the two parameters depends on the production system: fertility is more important than prolificacy in dairy systems, but not in meat systems. Acceptable fertility rates are around 90% whereas prolificacy depends on breed. Within breed, reproduction efficiency can vary widely, with fertility rates lower than 70% and prolificacy equal to 1 lamb per ewe lambing in some systems, but with the best flocks reaching 95-100% fertility and 1.3-1.5 lambs per ewe in non-prolific breeds and 1.8 to 2.5 in prolific breeds.
Ewes may fail to become pregnant because they are not mated or because they are unable to conceive after mating or AI. In addition, ewes may not maintain the pregnancy or lose some or all of their fetuses during pregnancy. A ewe may not be mated because she is not in the right condition to breed (e.g. due to ill health or age), because she is not cycling, or because the ram is not able to serve the ewe (e.g. due to ill health, libido or too many ewes). Ewes may not conceive because of poor egg or semen quality, stress (e.g. heat or handling), or pathology. Poor prolificacy in ewes can occur because of insufficient energy in the diet at breeding, poor body condition score, age, early embryo death or poor management of AI.
Each farm or flock may have different risk factors and prevalence for different causes of low fertility. Identifying the main reasons and risk factors for infertility are key steps in developing mitigation strategies. Recording fertility data and identifying when and why sheep do not lamb will help to improve reproduction efficiency.
SheepNet : SHaring Expertise and Experience towards sheep Productivity through NETworking (1 of 2)
Ongoing | 2016-2019
- Main funding source
- Horizon 2020 (EU Research and Innovation Programme)
- Geographical location
- France