1 Ovulation, Lactation and Milk Production 35 The goal of this lecture is to discuss basic physiology associated with the control of ovulation, lactation and milk production. The sections for this lecture are: Life is a series of chemical reactions occurring in compartmentalized environments. The main purpose of life is to keep itself alive Physiology, the study of how life works, is based on the simultaneous occurrence of the following three concepts: levels of organization structure / function relationship homeostatic regulation Hormonal profiles on ovulation, parturition and lactation Physiological changes at parturition & their links to metabolic disorders in dairy cows Thermoregulatory response jn young, calvesresponse to heat in a hutch environment Thermoregulatory response in adults, the fescue endophyte story in cows and the ergot toxicity in humans Milk and egg production and Ca regulation Ovulation, Parturition, Lactation & Milk Production Role of gonadal steroids and others on ovulation, parturition and lactation Physiological changes at parturition and their link to metabolic disorders Thermoregulatory response of calves to heat in a hutch environment The fescue Endophyte story in cows and that of Ergot toxicity in humans Milk production and Ca regulation Adaptation to lactation diet, elimination of hypo- calcemia, and immunomodulation to stimulate immune system at birth would reduce incidence of periparturient diseases in humans and cows.
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1
Ovulation, Lactation
and Milk Production 35 The goal of this lecture is to discuss basic
physiology associated with the control of ovulation, lactation and milk production.The sections for this lecture are:
Life is a series of chemical reactions occurring in compartmentalized environments. The main purpose of life is to keep itself alive
Physiology, the study of how life works, is based on the simultaneous occurrence of the following three concepts:
levels of organizationstructure / function relationshiphomeostatic regulation
Hormonal profiles on ovulation, parturition and lactation
Physiological changes at parturition & their links to metabolic disorders in dairy cows
Thermoregulatory response jn young, calves response to heat in a hutch environment
Thermoregulatory response in adults, the fescue endophyte story in cows and the ergot toxicity in humans
Milk and egg production and Ca regulation
Ovulation, Parturition,
Lactation & Milk Production Role of gonadal steroids and others on ovulation, parturition and lactation
Physiological changes at parturition and their link to metabolic disorders
Thermoregulatory response of calves to heat in a hutch environment
The fescue Endophyte story in cows and that of Ergot toxicity in humans
Milk production and Ca regulation Adaptation to lactation diet, elimination of hypo-calcemia, and immunomodulation to stimulate immune system at birth would reduce incidence of periparturient diseases in humans and cows.
2
Ovulation, Parturition,
Lactation & Milk Production Role of gonadal steroids and others on ovulation, parturition and lactation
Physiological changes at parturition and their link to metabolic disorders
Thermoregulatory response of calves to heat in a hutch environment
The fescue Endophyte story in cows and that of Ergot toxicity in humans
Milk production and Ca regulation Ruminal adaptation to lactation diet, elimination of hypoCa, and immunomodulation to stimulate immune system at calving would greatly reduce incidence of periparturient diseases in dary cows
Most metabolic diseases of dairy cows occur within the first two weeks of lactation. Others like laminitis can be traced back to that period
Role of gonadal steroids and others on ovulation, parturition and lactation
Physiological changes at parturition and their link to metabolic disorders
Thermoregulatory response of calves to heat in a hutch environment
The fescue Endophyte story in cows and that of Ergot toxicity in humans
Milk production and Ca regulation
Ruminal adaptation to lactation diet, elimination of hypoCa, and immunomodulation to stimulate immune system at calving would greatly reduce incidence of periparturient diseases in dary cows
Ovulation, Parturition,
Lactation & Milk Production
3
Ovulation, Parturition,
Lactation & Milk Production Role of gonadal steroids and others on ovulation, parturition and lactation
Physiological changes at parturition and their link to metabolic disorders
Thermoregulatory response of calves to heat in a hutch environment
The fescue Endophyte story in cows and that of Ergot toxicity in humans
Milk production and Ca regulation
E2 and P4 act in synchrony so that E2 promotes growth and P4 differentiation of their target tissues. E2 and P4 are steroids.
(E2)
Ovulation, Parturition,
Lactation & Milk Production Role of gonadal steroids and others on ovulation, parturition and lactation
Physiological changes at parturition and their link to metabolic disorders
Thermoregulatory response of calves to heat in a hutch environment
The fescue Endophyte story in cows and that of Ergot toxicity in humans
Milk production and Ca regulation
E2 and P4 act in synchrony so that E2 promotes growth and P4 differentiation of their target tissues. E2 and P4 are steroids.
(E2)
(P4)
4
Ovulation and Cyclicity
Role of gonadal steroids and others on ovulation, parturition and lactation
Physiological changes at parturition and their link to metabolic disorders
Thermoregulatory response of calves to heat in a hutch environment
The fescue Endophyte story in cows and that of Ergot toxicity in humans
Milk production and Ca regulation The general pattern for the hormonal control of reproduction. Ovulation is triggered by estradiol induction of the preovulatory surge of LH, an obligatory event for reproduction to occur.
E2 and P4 act in synchrony so that E2 promotes growth and P4 differentiation of their target tissues. E2 and P4 are steroids.
Parturition and its Control
Role of gonadal steroids and others on ovulation, parturition and lactation
Physiological changes at parturition and their link to metabolic disorders
Thermoregulatory response of calves to heat in a hutch environment
The fescue Endophyte story in cows and that of Ergot toxicity in humans
Milk production and Ca regulation The general pattern for the hormonal control of reproduction. Ovulation is triggered by estradiol induction of the preovulatory surge of LH, an obligatory event for reproduction to occur.
E2 and P4 act in synchrony so that E2 promotes growth and P4 differentiation of their target tissues. E2 and P4 are steroids.
5
Parturition and its Control
Role of gonadal steroids and others on ovulation, parturition and lactation
Physiological changes at parturition and their link to metabolic disorders
Thermoregulatory response of calves to heat in a hutch environment
The fescue Endophyte story in cows and that of Ergot toxicity in humans
Milk production and Ca regulation Parturition is associated with a decrease in blood Progesterone (P4) and an increase in blood Estradiol (E2). These combination depolarize the membrane potential of myometrial cells making them more suceptible to oxytocin & prostaglandins.
E2 and P4 act in synchrony so that E2 promotes growth and P4 differentiation of their target tissues. E2 and P4 are steroids.
P4
E2
Parturition and its Control
Role of gonadal steroids and others on ovulation, parturition and lactation
Physiological changes at parturition and their link to metabolic disorders
Thermoregulatory response of calves to heat in a hutch environment
The fescue Endophyte story in cows and that of Ergot toxicity in humans
Milk production and Ca regulation
E2 and P4 act in synchrony so that E2 promotes growth and P4 differentiation of their target tissues. E2 and P4 are steroids.
Parturition is associated with a decrease in blood Progesterone (P4) and an increase in blood Estradiol (E2). These combination depolarize the membrane potential of myometrial cells making them more suceptible to oxytocin & prostaglandins.
6
triggersonset ofparturition
mantainsparturition
Parturition and its Control
Role of gonadal steroids and others on ovulation, parturition and lactation
Physiological changes at parturition and their link to metabolic disorders
Thermoregulatory response of calves to heat in a hutch environment
The fescue Endophyte story in cows and that of Ergot toxicity in humans
Milk production and Ca regulation
E2 and P4 act in synchrony so that E2 promotes growth and P4 differentiation of their target tissues. E2 and P4 are steroids.
Lactation and its Control
Role of gonadal steroids and others on ovulation, parturition and lactation
Physiological changes at parturition and their link to metabolic disorders
Thermoregulatory response of calves to heat in a hutch environment
The fescue Endophyte story in cows and that of Ergot toxicity in humans
Milk production and Ca regulation Milk production results from the interaction of multiple metabolic hormonal systems on the mammary gland: hormones such as insulin, IGFs, GH, TSH, PRL, cortisol and aldosterone.
E2 and P4 act in synchrony so that E2 promotes growth and P4 differentiation of their target tissues. E2 and P4 are steroids.
GH
E2P4InsulinIGFsTSHPRLCortisolAldosterone
7
Lactation and its Control
Role of gonadal steroids and others on ovulation, parturition and lactation
Physiological changes at parturition and their link to metabolic disorders
Thermoregulatory response of calves to heat in a hutch environment
The fescue Endophyte story in cows and that of Ergot toxicity in humans
Milk production and Ca regulation Milk production results from the interaction of multiple metabolic hormonal systems on the mammary gland: hormones such as insulin, IGFs, GH, TSH, PRL, cortisol and aldosterone.
E2 and P4 act in synchrony so that E2 promotes growth and P4 differentiation of their target tissues. E2 and P4 are steroids.
GH
Lactation and its Control
Role of gonadal steroids and others on ovulation, parturition and lactation
Physiological changes at parturition and their link to metabolic disorders
Thermoregulatory response of calves to heat in a hutch environment
The fescue Endophyte story in cows and that of Ergot toxicity in humans
Milk production and Ca regulation Milk production results from the interaction of multiple metabolic hormonal systems on the mammary gland: hormones such as insulin, IGFs, GH, TSH, PRL, cortisol and aldosterone.
E2 and P4 act in synchrony so that E2 promotes growth and P4 differentiation of their target tissues. E2 and P4 are steroids.
8
Lactation and its Control
Role of gonadal steroids and others on ovulation, parturition and lactation
Physiological changes at parturition and their link to metabolic disorders
Thermoregulatory response of calves to heat in a hutch environment
The fescue Endophyte story in cows and that of Ergot toxicity in humans
Milk production and Ca regulation
E2 and P4 act in synchrony so that E2 promotes growth and P4 differentiation of their target tissues. E2 and P4 are steroids.
Suckling
Mechanoreceptors in nipple
Nervous pathway PIH orPRH (?)
Hypothalamus
Posterior pituitary Anterior pituitary
Prolactin Oxytocin
Milk secretion Myoepithelial cells
Milk ejection
+
Milk ejection results from binding oxytocin to its receptor on myoepithelial alveolar cells. Neuron linked “stress” related inputs to PVN and SON (oxytocin cell bodies loci) are also involved.
Periparturient Diseases
Role of gonadal steroids and others on ovulation, parturition and lactation
Physiological changes at parturition and their link to metabolic disorders
Thermoregulatory response of calves to heat in a hutch environment
The fescue Endophyte story in cows and that of Ergot toxicity in humans
Milk production and Ca regulation
immunefunctionat parturition
DMIat parturition
E2 and P4at parturition
cortisolat parturition
stressat parturition
immunesuppressionat parturition
Ruminal adaptation to lactation diet, elimination of hypoCa, and immunomodulation to stimulate immune system at calving would greatly reduce incidence of periparturient diseases in dary cows
How do we know that this THM is correct
9
Periparturient Diseases
Role of gonadal steroids and others on ovulation, parturition and lactation
Physiological changes at parturition and their link to metabolic disorders
Thermoregulatory response of calves to heat in a hutch environment
The fescue Endophyte story in cows and that of Ergot toxicity in humans
Milk production and Ca regulation Ruminal adaptation to lactation diet, elimination of hypoCa, and immunomodulation to stimulate immune system at calving would greatly reduce incidence of periparturient diseases in dary cows
How do we know that this THM is correct
immunefunctionat parturition
DMIat parturition
E2 and P4at parturition
cortisolat parturition
stressat parturition
immunesuppressionat parturition
Periparturient Diseases
Role of gonadal steroids and others on ovulation, parturition and lactation
Physiological changes at parturition and their link to metabolic disorders
Thermoregulatory response of calves to heat in a hutch environment
The fescue Endophyte story in cows and that of Ergot toxicity in humans
Milk production and Ca regulation Ruminal adaptation to lactation diet, elimination of hypoCa, and immunomodulation to stimulate immune system at calving would greatly reduce incidence of periparturient diseases in dary cows
How do we know that this THM is correct
immunefunctionat parturition
DMIat parturition
E2 and P4at parturition
cortisolat parturition
stressat parturition
immunesuppressionat parturition
10
Periparturient Diseases
Role of gonadal steroids and others on ovulation, parturition and lactation
Physiological changes at parturition and their link to metabolic disorders
Thermoregulatory response of calves to heat in a hutch environment
The fescue Endophyte story in cows and that of Ergot toxicity in humans
Milk production and Ca regulation Ruminal adaptation to lactation diet, elimination of hypoCa, and immunomodulation to stimulate immune system at calving would greatly reduce incidence of periparturient diseases in dary cows
How do we know that this THM is correct
immunefunctionat parturition
DMIat parturition
E2 and P4at parturition
cortisolat parturition
stressat parturition
immunesuppressionat parturition
P4
E2
Periparturient Diseases
Role of gonadal steroids and others on ovulation, parturition and lactation
Physiological changes at parturition and their link to metabolic disorders
Thermoregulatory response of calves to heat in a hutch environment
The fescue Endophyte story in cows and that of Ergot toxicity in humans
Milk production and Ca regulation Ruminal adaptation to lactation diet, elimination of hypoCa, and immunomodulation to stimulate immune system at calving would greatly reduce incidence of periparturient diseases in dary cows
How do we know that this THM is correct
immunefunctionat parturition
DMIat parturition
E2 and P4at parturition
cortisolat parturition
stressat parturition
immunesuppressionat parturition
Cows that
developed
hypocalcemia
and milk fever
Cows
that
did
not
11
Periparturient Diseases
Role of gonadal steroids and others on ovulation, parturition and lactation
Physiological changes at parturition and their link to metabolic disorders
Thermoregulatory response of calves to heat in a hutch environment
The fescue Endophyte story in cows and that of Ergot toxicity in humans
Milk production and Ca regulation Ruminal adaptation to lactation diet, elimination of hypoCa, and immunomodulation to stimulate immune system at calving would greatly reduce incidence of periparturient diseases in dary cows
How do we know that this THM is correct
immunefunctionat parturition
DMIat parturition
E2 and P4at parturition
cortisolat parturition
stressat parturition
immunesuppressionat parturition
Periparturient Diseases
Role of gonadal steroids and others on ovulation, parturition and lactation
Physiological changes at parturition and their link to metabolic disorders
Thermoregulatory response of calves to heat in a hutch environment
The fescue Endophyte story in cows and that of Ergot toxicity in humans
Milk production and Ca regulation Ruminal adaptation to lactation diet, elimination of hypoCa, and immunomodulation to stimulate immune system at calving would greatly reduce incidence of periparturient diseases in dary cows
How do we know that this THM is correct
immunefunctionat parturition
DMIat parturition
E2 and P4at parturition
cortisolat parturition
stressat parturition
immunesuppressionat parturition
12
Periparturient Diseases
Role of gonadal steroids and others on ovulation, parturition and lactation
Physiological changes at parturition and their link to metabolic disorders
Thermoregulatory response of calves to heat in a hutch environment
The fescue Endophyte story in cows and that of Ergot toxicity in humans
Milk production and Ca regulation Ruminal adaptation to lactation diet, elimination of hypoCa, and immunomodulation to stimulate immune system at calving would greatly reduce incidence of periparturient diseases in dary cows
How do we know that this THM is correct
immunefunctionat parturition
DMIat parturition
E2 and P4at parturition
cortisolat parturition
stressat parturition
immunesuppressionat parturition
Periparturient Diseases
Role of gonadal steroids and others on ovulation, parturition and lactation
Physiological changes at parturition and their link to metabolic disorders
Thermoregulatory response of calves to heat in a hutch environment
The fescue Endophyte story in cows and that of Ergot toxicity in humans
Milk production and Ca regulation Ruminal adaptation to lactation diet, elimination of hypoCa, and immunomodulation to stimulate immune system at calving would greatly reduce incidence of periparturient diseases in dary cows
How do we know that this THM is correct
immunefunctionat parturition
DMIat parturition
E2 and P4at parturition
cortisolat parturition
stressat parturition
immunesuppressionat parturition
13
Thermoregulatory Control
Role of gonadal steroids and others on ovulation, parturition and lactation
Physiological changes at parturition and their link to metabolic disorders
Thermoregulatory response of calves to heat in a hutch environment
The fescue Endophyte story in cows and that of Ergot toxicity in humans
Milk production and Ca regulation
effect onthermo-regulationby a minimalchange inenvironmentaltemperatureassociated with the useof shadeshows thesensitivityof the thermo-regulatorycontrolsystem
Supplemental shade lowers severity of heat stress, in calves housed in hutches in summer, as assessed by body t°C and respiratory rate, after minimal increases in environmental t°CHow do we know that this THM is correct
Thermoregulatory Control
Role of gonadal steroids and others on ovulation, parturition and lactation
Physiological changes at parturition and their link to metabolic disorders
Thermoregulatory response of calves to heat in a hutch environment
The fescue Endophyte story in cows and that of Ergot toxicity in humans
Milk production and Ca regulation
effect onthermo-regulationby a minimalchange inenvironmentaltemperatureassociated with the useof shadeshows thesensitivityof the thermo-regulatorycontrolsystem
Supplemental shade lowers severity of heat stress, in calves housed in hutches in summer, as assessed by body t°C and respiratory rate, after minimal increases in environmental t°CHow do we know that this THM is correct
14
Thermoregulatory Control
Role of gonadal steroids and others on ovulation, parturition and lactation
Physiological changes at parturition and their link to metabolic disorders
Thermoregulatory response of calves to heat in a hutch environment
The fescue Endophyte story in cows and that of Ergot toxicity in humans
Milk production and Ca regulation
effect onthermo-regulationby a minimalchange inenvironmentaltemperatureassociated with the useof shadeshows thesensitivityof the thermo-regulatorycontrolsystem
Supplemental shade lowers severity of heat stress, in calves housed in hutches in summer, as assessed by body t°C and respiratory rate, after minimal increases in environmental t°CHow do we know that this THM is correct
Thermoregulatory Control
Role of gonadal steroids and others on ovulation, parturition and lactation
Physiological changes at parturition and their link to metabolic disorders
Thermoregulatory response of calves to heat in a hutch environment
The fescue Endophyte story in cows and that of Ergot toxicity in humans
Milk production and Ca regulation
effect onthermo-regulationby a minimalchange inenvironmentaltemperatureassociated with the useof shadeshows thesensitivityof the thermo-regulatorycontrolsystem
Supplemental shade lowers severity of heat stress, in calves housed in hutches in summer, as assessed by body t°C and respiratory rate, after minimal increases in environmental t°CHow do we know that this THM is correct
15
Thermoregulatory Control
Role of gonadal steroids and others on ovulation, parturition and lactation
Physiological changes at parturition and their link to metabolic disorders
Thermoregulatory response of calves to heat in a hutch environment
The fescue Endophyte story in cows and that of Ergot toxicity in humans
Milk production and Ca regulation
effect onthermo-regulationby ingestion of a grass containingendophytesand summerhigh t°C,shows howthe thermo-regulatorycontrolsystem can be modulated
Losses in cow-calf productivity due to fescue toxicosity are significant. Endophyte ingestion interacts with high t°C to exacerbate the signs of toxicosis. Low PRL and melatonin secretion appears to be associated with the disease.
How do we know that this THM is correct
Thermoregulatory Control
Role of gonadal steroids and others on ovulation, parturition and lactation
Physiological changes at parturition and their link to metabolic disorders
Thermoregulatory response of calves to heat in a hutch environment
The fescue Endophyte story in cows and that of Ergot toxicity in humans
Milk production and Ca regulation
effect onthermo-regulationby ingestion of a grass containingendophytesand summerhigh t°C,shows howthe thermo-regulatorycontrolsystem can be modulated
Losses in cow-calf productivity due to fescue toxicosity are significant. Endophyte ingestion interacts with high t°C to exacerbate the signs of toxicosis. Low PRL and melatonin secretion appears to be associated with the disease.
How do we know that this THM is correct
16
Thermoregulatory Control
Role of gonadal steroids and others on ovulation, parturition and lactation
Physiological changes at parturition and their link to metabolic disorders
Thermoregulatory response of calves to heat in a hutch environment
The fescue Endophyte story in cows and that of Ergot toxicity in humans
Milk production and Ca regulation
effect onthermo-regulationby ingestion of a grass containingendophytesand summerhigh t°C,shows howthe thermo-regulatorycontrolsystem can be modulated
Losses in cow-calf productivity due to fescue toxicosity are significant. Endophyte ingestion interacts with high t°C to exacerbate the signs of toxicosis. Low PRL and melatonin secretion appears to be associated with the disease.
How do we know that this THM is correct
Thermoregulatory Control
Role of gonadal steroids and others on ovulation, parturition and lactation
Physiological changes at parturition and their link to metabolic disorders
Thermoregulatory response of calves to heat in a hutch environment
The fescue Endophyte story in cows and that of Ergot toxicity in humans
Milk production and Ca regulation
effect onthermo-regulationby ingestion of a grass containingendophytesand summerhigh t°C,shows howthe thermo-regulatorycontrolsystem can be modulated
Losses in cow-calf productivity due to fescue toxicosity are significant. Endophyte ingestion interacts with high t°C to exacerbate the signs of toxicosis. Low PRL and melatonin secretion appears to be associated with the disease.
How do we know that this THM is correct
Points of discussion related to t°C regulation and to reproduction associated with the fescue story
Reduced PRL & melatonin secretionAltered NT metabolism in H, Pit, Pin
Lowers feed intake (22%, 32 vs 22°C)Increase water intake (62%, 32 vs 22)
Decreased calving and growth rateDelayed onset of pubertyImpaired function of corpora luteaDecreased reproductive efficiencyReduced weight gainsLower milk production
Based on data explored in the course, how would you explain results reported in the J. of Animal Science listed above
17
Thermoregulatory Control
Role of gonadal steroids and others on ovulation, parturition and lactation
Physiological changes at parturition and their link to metabolic disorders
Thermoregulatory response of calves to heat in a hutch environment
The fescue Endophyte story in cows and that of Ergot toxicity in humans
Milk production and Ca regulation
effect onthermo-regulationby ingestion of a grass containingendophytesand summerhigh t°C,shows howthe thermo-regulatorycontrolsystem can be modulated
Ergocryptine is a dopamine receptor agonist used to inhibit Prolactin secretion in humans.
Ergot: Claviceps purpurea, a parasitic fungus on spoiled rye and other grains.
Its components and their derivatives include lysergic acid, lysergic acid amides, ergotamine,,ergocornine, ergocryptine, ergonovine, trimethylamine, histamine and acetylcholine,
The most common early effects of ingesting the grains are nausea, vomiting, diarrhea, tachycardia, abdominal pain, and coma..
Based on data explored in the course, how would you explain results related toErgot toxicity in humans
Ca, Milk and Egg Production
Role of gonadal steroids and others on ovulation, parturition and lactation
Physiological changes at parturition and their link to metabolic disorders
Thermoregulatory response of calves to heat in a hutch environment
The fescue Endophyte story in cows and that of Ergot toxicity in humans
Milk production and Ca regulation
milk and egg productionare linked bythe control ofCa metabolism.Thus the role of PTH, VitDand calcitoninare importantto understandmanagement techniquesused in bothIndustries, as well as in human lactation.
Adequate blood calcium (Ca) and phosporus (P) concentrations are vital to normal animal function. Homeostatic mechanisms normally achieved this. Ca & P are key minerals in bone development in humans and cows, and egg formation in chickens.
18
Ca, Milk and Egg Production
Role of gonadal steroids and others on ovulation, parturition and lactation
Physiological changes at parturition and their link to metabolic disorders
Thermoregulatory response of calves to heat in a hutch environment
The fescue Endophyte story in cows and that of Ergot toxicity in humans
Milk production and Ca regulation
milk and egg productionare linked bythe control ofCa metabolism.Thus the role of PTH, VitDand calcitoninare importantto understandmanagement techniquesused in bothIndustries, as well as in human lactation.
Adequate blood calcium (Ca) and phosporous (P) concentrations are vital to normal animal function. Homeostatic mechanisms normally achieved this. Ca & P are key minerals in bone development in humans and cows, and egg formation in chickens.
Disorders of Ca metabolism may arise from abnormal levels of PTH or vitD.
Possible consequences of hypercalcemia and hypophosphatemia
Reduced excitability of muscle and nerve tissue leads to muscle weakness and neurological disorders. Cardiac disorders might also occur.
Excess mobilization of Ca and PO4 from bone leads to osteoporosis.
An increased incidence of Ca containing kidney stones occurs because the excess quantity of Ca being filtered may precipitate and form stones.
Ca, Milk and Egg Production
Role of gonadal steroids and others on ovulation, parturition and lactation
Physiological changes at parturition and their link to metabolic disorders
Thermoregulatory response of calves to heat in a hutch environment
The fescue Endophyte story in cows and that of Ergot toxicity in humans
Milk production and Ca regulation
milk and egg productionare linked bythe control ofCa metabolism.Thus the role of PTH, VitDand calcitoninare importantto understandmanagement techniquesused in bothIndustries, as well as in human lactation.
Adequate blood calcium (Ca) and phosporus (P) concentrations are vital to normal animal function. Homeostatic mechanisms normally achieved this. Ca & P are key minerals in bone development in humans and cows, and egg formation in chickens.
The Ca content of human milk is about 36 mg per 100
ml. A lactating woman produces about 750 ml of milk
daily, which represents about 280 mg of Ca.
For a maternal urinary Ca of 100 mg/day and skin loss
of 60 mg/day, the required absorption is 440 mg/day -
the same as at puberty.
However, although it is known that bone is lost during
lactation & restored after weaning, early reports that
this bone loss could be prevented by Ca supplemen-
tation have not been confirmed in controlled studies.
19
Ca, Milk and Egg Production
Role of gonadal steroids and others on ovulation, parturition and lactation
Physiological changes at parturition and their link to metabolic disorders
Thermoregulatory response of calves to heat in a hutch environment
The fescue Endophyte story in cows and that of Ergot toxicity in humans
Milk production and Ca regulation
milk and egg productionare linked bythe control ofCa metabolism.Thus the role of PTH, VitDand calcitoninare importantto understandmanagement techniquesused in bothIndustries, as well as in human lactation.
Adequate blood calcium (Ca) and phosporus (P) concentrations are vital to normal animal function. Homeostatic mechanisms normally achieved this. Ca & P are key minerals in bone development in humans and cows, and egg formation in chickens.
There are 9grs of Ca in ECF and 3grs in plasma. Daily output of Ca in milk is about 25grs.Lactating cows prevent hypocalcemia by taking Ca from bone or by increasing GI-Ca absorption.Bone Ca mobilization is regulated by PTH. VitD is needed to efficiently absorbed dietary Ca.Hypocalcemia and milk fever occur when cattle do not remove enough Ca from their bones and the diet to replace the Ca lost in the milk.
Ca, Milk and Egg Production
Role of gonadal steroids and others on ovulation, parturition and lactation
Physiological changes at parturition and their link to metabolic disorders
Thermoregulatory response of calves to heat in a hutch environment
The fescue Endophyte story in cows and that of Ergot toxicity in humans
Milk production and Ca regulation
milk and egg productionare linked bythe control ofCa metabolism.Thus the role of PTH, VitDand calcitoninare importantto understandmanagement techniquesused in bothIndustries, as well as in human lactation.
Adequate blood calcium (Ca) and phosporus (P) concentrations are vital to normal animal function. Homeostatic mechanisms normally achieved this. Ca & P are key minerals in bone development in humans and cows, and egg formation in chickens.
10% of total body Ca is secreted into shell, daily.Egg shell is made of calcium carbonate.PTH mobilize bone Ca when Ca deposition in the shell exceeds Ca absorbed by intestines.Reciprocal relation of PTH and Ca during the egg cycle.Ca transporters in laying birds shell gland is controlled by estrogen.
20
Ca, Milk and Egg Production
Role of gonadal steroids and others on ovulation, parturition and lactation
Physiological changes at parturition and their link to metabolic disorders
Thermoregulatory response of calves to heat in a hutch environment
The fescue Endophyte story in cows and that of Ergot toxicity in humans
Milk production and Ca regulation
milk and egg productionare linked bythe control ofCa metabolism.Thus the role of PTH, VitDand calcitoninare importantto understandmanagement techniquesused in bothIndustries, as well as in human lactation.
There are three tissue target in Ca metabolism that control blood levels of Ca: bones, kidneys and gut. PTH acts on bone and kidneys, vitD acts on the gut, and calcitonin in all three of them.
Ca, Milk and Egg Production
Role of gonadal steroids and others on ovulation, parturition and lactation
Physiological changes at parturition and their link to metabolic disorders
Thermoregulatory response of calves to heat in a hutch environment
The fescue Endophyte story in cows and that of Ergot toxicity in humans
Milk production and Ca regulation
milk and egg productionare linked bythe control ofCa metabolism.Thus the role of PTH, VitDand calcitoninare importantto understandmanagement techniquesused in bothIndustries, as well as in human lactation.
blood
Ca bone
kidney
intestine
resorption
formation
reabsorptionfiltration
secretion
absorptionPTH and Vit.D
increase bloodCa
while
Calcitonin
decreases it
PTH
Calcitonin
PTH
Calcitonin
Vit. D
calcium receptor
parathyroid gland
PTH
PTH receptorGs / AC
Gq / PLC
bone resorption, osteoclast
kidney, Ca reabsorption, Vit. D
intestine, Ca absorption
Calcitonin
thyroid gland
calcium
receptor
Calcitonin
receptor
Gs / AC
bone formation, osteoblast
kidney, Ca filtration
intestine, Ca secretion
blood Ca
decrease
blood Caincreas
e
There are three tissue target in Ca metabolism that control blood levels of Ca: bones, kidneys and gut. PTH acts on bone and kidneys, vitD acts on the gut, and calcitonin in all three of them.
21
Ca, Milk and Egg Production
Role of gonadal steroids and others on ovulation, parturition and lactation
Physiological changes at parturition and their link to metabolic disorders
Thermoregulatory response of calves to heat in a hutch environment
The fescue Endophyte story in cows and that of Ergot toxicity in humans
Milk production and Ca regulation
milk and egg productionare linked bythe control ofCa metabolism.Thus the role of PTH, VitDand calcitoninare importantto understandmanagement techniquesused in bothIndustries, as well as in human lactation.
There are three tissue target in Ca metabolism that control blood levels of Ca: bones, kidneys and gut. PTH acts on bone and kidneys, vitD acts on the gut, and calcitonin in all three of them.
Ca, Milk and Egg Production
Role of gonadal steroids and others on ovulation, parturition and lactation
Physiological changes at parturition and their link to metabolic disorders
Thermoregulatory response of calves to heat in a hutch environment
The fescue Endophyte story in cows and that of Ergot toxicity in humans
Milk production and Ca regulation
milk and egg productionare linked bythe control ofCa metabolism.Thus the role of PTH, VitDand calcitoninare importantto understandmanagement techniquesused in bothIndustries, as well as in human lactation.
There are three tissue target in Ca metabolism that control blood levels of Ca: bones, kidneys and gut. PTH acts on bone and kidneys, vitD acts on the gut, and calcitonin in all three of them.
22
Ca, Milk and Egg Production
Role of gonadal steroids and others on ovulation, parturition and lactation
Physiological changes at parturition and their link to metabolic disorders
Thermoregulatory response of calves to heat in a hutch environment
The fescue Endophyte story in cows and that of Ergot toxicity in humans
Milk production and Ca regulation
milk and egg productionare linked bythe control ofCa metabolism.Thus the role of PTH, VitDand calcitoninare importantto understandmanagement techniquesused in bothIndustries, as well as in human lactation.
There are three tissue target in Ca metabolism that control blood levels of Ca: bones, kidneys and gut. PTH acts on bone and kidneys, vitD acts on the gut, and calcitonin in all three of them.
Ca, Milk and Egg Production
Role of gonadal steroids and others on ovulation, parturition and lactation
Physiological changes at parturition and their link to metabolic disorders
Thermoregulatory response of calves to heat in a hutch environment
The fescue Endophyte story in cows and that of Ergot toxicity in humans
Milk production and Ca regulation
milk and egg productionare linked bythe control ofCa metabolism.Thus the role of PTH, VitDand calcitoninare importantto understandmanagement techniquesused in bothIndustries, as well as in human lactation.
There are three tissue target in Ca metabolism that control blood levels of Ca: bones, kidneys and gut. PTH acts on bone and kidneys, vitD acts on the gut, and calcitonin in all three of them.
23
Ca, Milk and Egg Production
Role of gonadal steroids and others on ovulation, parturition and lactation
Physiological changes at parturition and their link to metabolic disorders
Thermoregulatory response of calves to heat in a hutch environment
The fescue Endophyte story in cows and that of Ergot toxicity in humans
Milk production and Ca regulation
milk and egg productionare linked bythe control ofCa metabolism.Thus the role of PTH, VitDand calcitoninare importantto understandmanagement techniquesused in bothIndustries, as well as in human lactation.
There are three tissue target in Ca metabolism that control blood levels of Ca: bones, kidneys and gut. PTH acts on bone and kidneys, vitD acts on the gut, and calcitonin in all three of them.
Ca, Milk and Egg Production
Role of gonadal steroids and others on ovulation, parturition and lactation
Physiological changes at parturition and their link to metabolic disorders
Thermoregulatory response of calves to heat in a hutch environment
The fescue Endophyte story in cows and that of Ergot toxicity in humans
Milk production and Ca regulation
milk and egg productionare linked bythe control ofCa metabolism.Thus the role of PTH, VitDand calcitoninare importantto understandmanagement techniquesused in bothIndustries, as well as in human lactation.
There are three tissue target in Ca metabolism that control blood levels of Ca: bones, kidneys and gut. PTH acts on bone and kidneys, vitD acts on the gut, and calcitonin in all three of them.
ç
24
Ca, Milk and Egg Production
Role of gonadal steroids and others on ovulation, parturition and lactation
Physiological changes at parturition and their link to metabolic disorders
Thermoregulatory response of calves to heat in a hutch environment
The fescue Endophyte story in cows and that of Ergot toxicity in humans
Milk production and Ca regulation
milk and egg productionare linked bythe control ofCa metabolism.Thus the role of PTH, VitDand calcitoninare importantto understandmanagement techniquesused in bothIndustries, as well as in human lactation.
There are three tissue target in Ca metabolism that control blood levels of Ca: bones, kidneys and gut. PTH acts on bone and kidneys, vitD acts on the gut, and calcitonin in all three of them.
irradiation
7-Dehydro
cholesterol
(pro Vit. D)
Cholecalci-
ferol
(Vit.
D3)
25-Hydroxy
cholecalciferol
(25 - (OH) - D3)
1, 25 -
Dihydroxy
cholecalci-
ferol
( 1, 25 -
(OH)2
D3 )
24, 25 - Dihydroxy
cholecalciferol
( 24, 25 - (OH)2 D3 )
25 -
hydroxy-
lation1 -
hydroxy
- latio
n
24 -
hydroxy-
lation
kidney
liver
skin
-
PTH
Low PO4
Low Ca
Estrogen
Prolactin
GH
Placental
lactogen
+
Ca, Milk and Egg Production
Role of gonadal steroids and others on ovulation, parturition and lactation
Physiological changes at parturition and their link to metabolic disorders
Thermoregulatory response of calves to heat in a hutch environment
The fescue Endophyte story in cows and that of Ergot toxicity in humans
Milk production and Ca regulation
milk and egg productionare linked bythe control ofCa metabolism.Thus the role of PTH, VitDand calcitoninare importantto understandmanagement techniquesused in bothIndustries, as well as in human lactation.
There are three tissue target in Ca metabolism that control blood levels of Ca: bones, kidneys and gut. PTH acts on bone and kidneys, vitD acts on the gut, and calcitonin in all three of them.