Nutrition in reproduction Flashcards
Define the concept of negative energy balance in dairy cows
Using more energy than is being taken in, often the case following parturition in dairy cows due to high amount of energy required for lactation
What is the role of cholestrol in reproduction?
- Used to produce sex hormones
- Consumed in diet
Describe the role of insulin in reproduction
- Direct action on antral follicle growth adn steroid production
- Regulator of circulatory IGF via effects on GH receptors
Describe the role of IGF in reproduction
- Enhances ovarian action of gonadotrophins (IGF-I)
- Direct effect on follicle growth and steroidogenesis (IGF-I and II)
Describe the role of leptin in reproduction
- Inhibits oestradiol secretion
- Increases folliculogenesis
Describe the effect of selenium deficiency in reproduction
Deficiency leads to increased incidence of cystic ovaries
Describe the effects of thiomolybdate toxicity on reproduction in the cow
- Causes copper deficiency
- Gross alterations in pathology and function of pituitary
- Ovarian somatic cell effects (decreased steroidogenesis)
- Decreased progesterone = decreased inferon tau = decreased maternal recognition of pregnancy meaning increased pregnancy failure
How is puberty affected by nutrition?
Puberty determined by size, so need good nutrition to get to puberty
What are the effects of copper deficiency in bovine reproduction?
- Increased age at puberty
- Reduced conception rates
- Failure to display oestrus behaviour
- Irregular oestrus, ultimately anoestrus
- Reduced feed intake and conversion efficiency
What are the reproductive effects of zinc deficiency?
- Decreased numbers born
- Decreased birth weight
What are the effects of iodine deficiency on bovine reproduction?
- Increased incidence of cystic ovaries
- Lowered conception rates
- Irregular oestrus, anoestrus
- Abortions, still births, weak and hairless calves
- Abnormal brain development
- Decreased newborn viability (thyroid hormones involved in surfactant production)
- Retained placenta
- Increased post-natal susceptibility to hypothermia
Outline the practice of flushing
- Sheep
- 2 weeks prior to tupping, ewes on fresh good pasture of supplementary feed
- Increase BCS of 2/2.5 by 0.5 (aim for BCS of 3)
- Rising plane of nutrition
- Aim to make sheep think can support more lambs
What are the effects of flushing?
- Increases fecundity
- Increases leptin, insulin
- Decreases GH and IGF unaffected
- Transient increase in FSH, decreased oestradiol (increased folliculogenesis so more ovulations)
Give some nutritional causes of pregnancy loss in the cow
- Vit A, selenium, phosphorous and copper deficiencies
- Negative energy balance
- High intake of rumen-degradable protein (toxic effects of blood urea or ammonia on embryo)
- Ingestion of phytooestrogens
Describe the effects of undernutrition in early and late gestation
- Early: leads to increased placental weight
- Late: leads to decreased placental weight
Describe the effect of over-conditioning on parturition?
Being fatter increases dystocia
Outline the effect of selenium in parturition
- Important in membrane expulsion along with calcium
- Deficiency can lead to retained placenta and increased incidence of endometritis
Outline the effects of copper deficiency post-partum
- Hair pigmentation and texture affected (ginger, spectacles)
- Reduced energy utilisation
- Swayback
What is the effect of zinc deficiency post-partum?
Pregnancy toxaemia
Describe what happens post-partum with negative energy balance
- Mobilisation of body reserves
- Delayed return to cyclicity
- Circulatory glucose, insulin and IGF-I reduced
- Increase NEFAs
- Ketosis
- Impaired follicle development and /or luteal function
How can being overweight affect male reproductive function?
- Decreased fertility
- Fat covering testes decreasing cooling and so impairing sperm function
Outline how nutrition can affect male reproductive function
- Significant effects on hormones adn regulation of reproduction
- Signficant effects on spermatogenesis
- Zinc: major roles in DNA and protein replication, essential for spermatogenesis and deficiency gives decreased libido and testicular size
- Iodine deficiency leads to decreased libido and semen quality
