9. Environmental management

Question 1

Define stress

Answer 1

Drastic change in climate or management that is severe enough to elicit behavioural or physiological response from the animal. Environmental stressors include heat, cold, transport.

Question 2

Name a few of the negative effects of heat stress

Answer 2

• delays puberty in males and females by depressing appetite and slowing the growth rate.
• Lower semen quality = decreased conception rate
• increased abnormalities in sperm
• Bos taurus have reduced intensity and shorter periods of estrus
• low expression of estrus (35-40%)
• Extended post weaning anestrus is frequent during summer
• In superovulated cows heat stress reduces fertilization rate.
• Has an effect on embryo quality and survival
• At late gestation heat stress affects foetal growth.

Question 3

Give the process of what happens to a cow when it experiences heat stress.

Answer 3

• Heat stress
• decreased feed intake
• negative energy balance
• decreased GnRH and LH
• decreased oestradiol secretion
• Poor oestrus expression and prolonged follicular dominance
• low fertilization rate and poor embryo quality
• embryonic loss

Question 4

Cold stress affect _____ cattle

Answer 4

Zebu

Question 5

Stress causes a release of ___

Answer 5

Adrenocorticotropic hormone (ACTH) from the anterior pituitary, which in return stimukates the release of cortisol and other glucocorticoids from the adrenal cortex.