文档介绍：第 五 章 分 娩 Parturation
Parturition or labor
孕畜经过正常怀孕期满(胎儿发育成熟)，母体将胎儿及其从属物从子宫排出体外生理过程，叫分娩。 瓜熟蒂落
What is Phavior
and ejection of milk
of uterine contractions
of pregnancy
Initiates parturition
and lung development
Cortisol - stimulates lung surfactant
Prolactin completes final
mammary development
and milk secretion
Fescue(牛茅草) toxicity problems:
Ergot(麦角菌) causes inhibition of
prolactin release and thus milk production
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表面活性剂
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Significance of initial hormonal changes
Progesterone - removes block on uterine contractions.
Estrogen - makes uterus more responsive to induction of
contractions ., more irritable and smooth
muscle tissue stimulation.
Events just Prior to Parturition:
1. Pelvic ligaments soften - Tail head sinks due to estrogens
and relaxin.
2. Cervix softens and begins secreting stringy(线状) mucus - estrogens and relaxin.
.
Allows myometrial muscle fibers to work together in bundles
Induction of
oxytocin receptors
Increased water content in cervical tissue and
cervical plug(子宫颈粘液塞) is removed
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3. Swelling of vulva.
4. Udder swells - fills with first milk and due to edema:
5. Fetus moves into proper position - resting on thorax, front feet and head facing the cervix
Collagenase (胶原酶)breaks down collagen which also widens the pelvis
Prolactin, Estrogens and glucocorticoids
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Signs of Approaching Parturition
Distended abdomen
Mammary development & milk secretion
Swollen vulva and relaxed pelvic ligaments
Mucous discharge
Relentlessness and separation from group
Labor and Contractions
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Physical Signs of Parturition
Swollen udder
Enlarged or dropped abdominal area
Swollen vulva
Separation from other animals
Swollen or leaking teats(漏乳)
Increased mucu