Male Fertility

explain the hormone pulses in a male, including the role of each hormone

Pulses occur in this order: GnRH, LH, testosterone; occur every 4-8 hours, GnRH causes the release of LH from the anterior pituitary which causes leydig cells to produce testosterone

why are pulses of hormones necessary

The presence of LH reduces the number of LH receptors on leydig cells, so sustained LH would lead to lower testosterone

explain the negative feedback loops in the male

GnRH is released to the anterior pituitary where LH is released to the leydig cells where testosterone is produced, testosterone has a negative feedback on the tonic center, T4 is sent to the sertoli cells where it is converted into E2 and DHT which have negative feedback on the tonic center; GnRH also triggers the release of FSH to sertoli cells which triggers a negative feedback of inhibin on the anterior pituitary

4 parts of a breeding soundness exam

mating ability, libido, physical exam, sperm assessment

how are mating and libido tested in a BSE

observing a male around females in heat

describe the physical examination of a BSE

feet and legs (no signs lameness, healthy hooves), BCS of 5 or 6, clear vision, testes move freely in scrotum and testes and epididymis are smooth and symmetrical upon palpation along with scrotum, no adhesions warts or abscesses on the sheath and penis, measure scrotal circumference

4 parts of semen evaluation

ejaculate volume, sperm concentration, sperm motility, sperm morphology

normal ejaculate volumes for bulls, bucks, rams, dogs

bull 3-8ml, boar 200-500ml, ram .5-1.8ml, buck .5-2ml, dog 2-20ml

gross motility vs individual motility

gross motility is the swirl pattern, individual motility is the % of motile sperm

satisfactory % of motile sperm cells

60-70%

3 main parts of sperm cell

head, midpiece, tail

describe the head of the sperm cell

nucleus (DNA), acrosome which contains acrosin and hyaluronidase which are necessary to penetrate the zona pellucida during fertilization

describe the midpiece of the sperm cell

contains mitochondria to provide energy for the tail

describe the tail of the sperm cell

flagellum for movement

sperm abnormality examples

bent tail, abnormal head shape, two heads, two tails, proximal cytoplasmic droplet