Advanced reproductive physiology part 2
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فیزیولوژی تولید مثل پیشرفته. Advanced reproductive Physiology (part 2). By: A. Riasi (PhD in Animal Nutrition & Physiology). What is early embryonic loss?. From conception to the time of maternal recognition of pregnancy, e mbryonic loss is high. The early embryonic loss is affected by:

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Advanced reproductive Physiology (part 2)

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فیزیولوژی تولید مثل پیشرفته

Advanced reproductive Physiology(part 2)

By: A. Riasi

(PhD in Animal Nutrition & Physiology)

What is early embryonic loss?

  • From conception to the time of maternal recognition of pregnancy, embryonic loss is high.

  • The early embryonic loss is affected by:

    • Nutritional factors

    • Reproductive management

  • The relationship of body condition score and early embryonic loss (Mapletoft et al. 1986)

  • Energy deficiency should be considered as a problem in herds, in this condition:

    • Cows lose excessive amounts of body condition during early lactation.

    • Cows are not cycling normally by 30-40 days after calving.

  • Cows in better energy balance had greater intrafollicular IGF-I and plasma progesterone levels and produce more oocytes graded as good.

  • Therefore, NEB not only delays resumption of ovulatory cyclesbut it might also influence the quality of occytes once cows are inseminated.

  • When heifers are fed inadequate amounts of energy, they reach sexual maturity later.

  • If energy deficient rations are fed to heifers that have begun to have normal estrous cycles, they may stop cycling.

  • The first key is to understand the nutrient needs of cattle at different phases of production and reproduction.

  • The second key is to know the nutrition content of the predominate feedstuff and supplement as needed.

  • The primary nutrients that should be considered in providing for good reproduction are:

    • Energy

    • Protein

    • Minerals

    • Vitamins

    • Fiber

  • Energy intake may be the most important nutritional factor affecting reproduction.

  • Excessive energy intake during late lactation and the dry period can cause “fat cow” problems

  • In cows with NEB, blood concentration of NEFA icrease and at the same time IGF-I, glucose and insulin are low.

  • It has shown cyclic cattle that are underfed have progressively smaller and less estrogenic dominant follicles (Bossis et al., 1999).

Poor nutrition

  • Lower metabolic hormones:

    • Somatotropin

    • Insulin

    • IGF-I

Low energy intake

Smaller and less estrogenic dominant follicle

Lower sroidogenic capacity of corpora lutea

Smaller corpora lutea

Lower progesterone concentration in blood

Lower reproduction performance

  • Expression of hepatic growth hormone receptor (GHR-1A) is thought to be responsible for the concentrations of IGF-I in plasma of cows.

  • IGF-I is an important hormonal signal that influences reproductive events:

    • Stimulation of cell mitogenesis

    • Hormonal production

    • Embryo development

  • Feeding diets that promote greaterinsulin concentrations are benefit for fertility.

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