Card Set Information
what does stress do to lactating animals?
releases norepinephrine that blocks oxytocin, decreases capillary blood flow and constricts ducts (less milk production)
What does oxytocin do to myopthilium?
contracts it and increases alveolar and intramamary pressure.
what does oxytocin do to mammary ducts?
dilates the terminal and capillary ducts from the alveolus
what effect does oxytocin have on blood flow?
it increases the cardiac output to the heart
what is the timing of oxytocin?
from stimulus to contraction is about 20-60 sec. attach unit opne min after stimulus
what is the reflex arc for milk ejection?
exteroceptive stimulus, CNS, cerebral cortex, hypothalmus, anterior pituitary, oxytocin action.
what effect does photo period have on lactating animals?
extended photo period (16hrs per day) increases mamary output and persistency.
what are targets for oxytocin?
myoepethilian cells, terminal ducts, and precappilary sphincter
what factors effect milk yield?
Age, parity, pressure, photoperiod, and ambient temperature.
why do long photoperiods effect milk yield?
light increases prolactin levels in serum, which allows for more milk production. (transcription of milk protein)
what does a pregnancy do to milk yield?
it decreases yield as the number of cells starts to taper off.
what is residual milk?
15-20% of milk product that cannot be gathered.
what are the galactopoetic hormones?
prolactin, cortoicosteroids, oxytocin, and GH (IGF-1)
what are the determining factors of galactopoeisis?
number of secretory cells, metabolic activity, and efficiency of milk ejection.
what is galactopoiesis?
to enhance or sustain an established lactation.
what are lactogenic hormones?
progesterone withdrawl, increase glucocorticoid/prolactin
why is a dry period neccessary for lactation?
because without a dry period the subsequent milk yield would be around 30% less.
what is involution?
natural regression of MG after peak lactation.
for mammiogenesis what do estrogens do?
assist mammary duct growth.
for mammiogenisis what what do progesterone & estrogen do?
assist lobular and alveolar growth.
what is the blood:milk unit ratio?
500 units blood= 1 unit milk.
what effect does over feeding have on mammary development?
critical period 3 months of age over feeding can increase extra parenchymal fat and decrease milk production (permanent effect) and parenchymal tissue growth.
what is mamiogenesis?
growth and morphological development of mammary tissue.
what is lactogenesis?
last stages of biochemical and structural differentiation of alveolar epithilial cells during periparturient period.
what is the expected serving capacity for a yearling bull?
1-15 in 60 days.
what is the expected serving capacity for 2 year old bulls?
25-30 in 60 days.
what is the expected serving capacity for 3 year on older bulls?
40-50 in 60 days.
Ram yearling serving capacity?
15-25 in 60 days.
ram mature serving capacity?
30-50 in 60 days.
boar serving 8.5-12 months age?
1 ejaculation per day, 7/week, 8-10 services per month.
boar greater than 12 months serving?
2 ejaculations/day, 10/week, 10-12 services/ month