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Nutrition and reproduction the sheep model

Why are nutrition-reproduction relationships important?. Wild animals exploiting food resources to the full e.g. clutch size in birds - more food means = more eggs = more young reared.Domestic animals More offspring = more money!. Why sheep? . Economically importantMuch is known of their ph

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Nutrition and reproduction the sheep model

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    1. Nutrition and reproduction – the sheep model Stewart M. Rhind

    2. Why are nutrition-reproduction relationships important? Wild animals – exploiting food resources to the full – e.g. clutch size in birds - more food means = more eggs = more young reared. Domestic animals –More offspring = more money!

    3. Why sheep? Economically important Much is known of their physiology Reproductive performance is closely related to nutrition in some breeds Can be used to investigate underlying mechanisms

    4. A few basic facts Ewes typically breed once per year, in the autumn and produce 1 to 4 lambs Ewes (and females of many other species) are “designed” to gain and lose large fat reserves The fat reserves have to “speak to” the ovaries!

    5. When and how does nutrition determine reproduction? Number of eggs produced. Number of embryos that survive. Reproductive performance can be adjusted at EVERY stage - during gestation - before gestation - before the mother is born!

    6. Reproductive rate is matched to nutritional resources

    7. When does nutrition determine lambing rate? During gestation – loss of embryos

    8. Embryonic loss Nutrition effects : Undernutrition during first month of gestation can increase embryo death rate Overnutrition during first month of gestation can increase embryo death rate

    9. Embryonic loss Other causes of increased loss: Parity (higher in first) Simultaneous lactation Heat and cold stress High ovulation rate (breed or hormonal treatment)

    10. When does nutrition determine lambing rate? During gestation – loss of embryos Days, weeks, months and years before mating – ovulation rate

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