Repro and nutrition Flashcards
How does nutrition exerts its major effects on
reproduction?
Through Hormones s Sex Hormones — synthesied from cholesterol Energy status hormones — Leptin, Insulin, IGF
Insulin is a metabolic hormone how does it exerts its effects on reproduction?
— Direct action on antral follicle growth and steroid
production
— Regulator of circulatory IGF (via effects on GH
receptors)
IGF is a metabolic hormone how does it exerts its effects on reproduction?
— Enhances ovarian action of gonadotrophins (IGF I)
— Direct effect on follicle growth and steroidogenesis (IGF I and II)
Leptin is a metabolic hormone how does it exert its effects on reproduction?
— At physiological levels inhibits oestradiol secretion and increases folliculogenesis.
How does a high intake of rumen degradable protein affect reproduction?
Toxic effects of blood urea or ammonia on fetus.
How does negative energy balance effect reproduction?
. Mobilise body reserves
. Delayed return to cyclicity (calving to 1st ovulation)
. circulatory glucose, insulin, IGF I reduced
. Increase NEFA (non esterified fatty acids)
— can be used as a measure of fat mobilisation
— Poss. direct toxic effect on follicles and oocytes
. Ketosis
. Impaired follicle development and/or luteal
function
What is flushing and how does it effect reproduction?
. Usual practice is 2 weeks prior to start of tupping
move ewes onto fresh good pasture or supplementary feed. (3 days of lupins or glucose)
. Ideally from a condition score of 2-2.5, looking to
increase condition by 0.5
. A rising plane of nutrition
. Increases fecundity (number of lambs/ewe)
. Increases Leptin, Insulin, decreases Growth
hormone and IGF unaffected
. Transient increase in FSH, decreased oestradiol
(increased negative feedback gives increased FSH
and increased Folliculogenesis)
How does selenium deficiency effect reproduction?
. Increased incidence of retained placenta
. Increased incidence of cystic ovaries
. High embryonic mortality (3-4 weeks post
conception)
. Decreased conception rates
. Increased incidence of endometritis
. Birth of premature, weak or dead calves
How does copper deficiency effect reproduction?
. Delay of puberty
. Failure to display oestrus behaviour
. Irregular oestrus, ultimately anoestrus
. Reduced conception rates
. Reduced peak ovulatory LH
. Reduced feed intake and conversion efficiency
. Hair pigmentation and texture (ginger/spectacles)
. Reduced energy utilisation (cytochrome c oxidase)
. Swayback
How does zinc effect reproduction in the male?
. Zinc has major roles in DNA and Protein replication . Essential for spermatogenesis . Deficiency gives decreased libido and testicular size
How does zinc effect reproduction in the female?
. In female mild deficiency decreases numbers
born, birth weight and leads to increased
pregnancy toxaemia (anorexia)
. Severe deficiency in early pregnancy leads to
teratogenic effects
How does iodine effect reproduction?
Reproductive symptoms — Lowered conception rates — Irregular oestrus, anoestrus — Retained placenta - Abortions — Still births, birth of weak and/or hairless calves — Cystic ovaries — In male decreased libido and semen quality
What is pregnancy toxaemia (aka twin lamb disease)?
A disease affecting ewes during the last few weeks of gestation. Mainly affects twin or multiple bearing ewes. The condition occurs when the ewe does not receive an adequate energy supply during a time when the rapidly growing foetuses drain carbohydrate stores. This results in a sub-clinical ketosis which can quickly progress to a clinical pregnancy toxaemia. It is a serious condition which can be fatal and most frequently affects lowland flocks.
Very similar to ketosis in cows.
