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defend or refute. Synthesis of lactose in alveolar epithelial cells is a major factor that controls galactopoesis.
DEFEND. lactose increases osmotic pressure which helps sequester water, which increases yield of milk.
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defend or refute. Concentration of lactose in alveolar epithelial cells is correlated positively with yield of milk.
DEFEND. osmotic draw of lactose increases water which increases milk yield.
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name a component of milk that is associated with synthesis of lactose. EXPLAIN.
α-lactalbumin, protein that helps with synthesis
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name three hormones that exert a direct role, positive or negative, in lactogenesis. Also, name a type of endocrine cell for each lactogenic hormone
lactogenic hormone, effect, endocrine cell
- prolactin, positive, lactotrope
- progesterone, negative, luteal cell
- cortisol, positive, zona fasiculata in adrenal cortex
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name two intracellular organelles for the for the endocrine cells involved in lactogenesis and describe the changes that support lactogenesis.
- mitochondria-increase in number
- golgi apparatus-increase in number
- endoplasmic reticulum-increase
- ribosomes-increase in number
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what is the type of cell that contains the organelles that effect lactogenesis?
alveolar epithelial cell
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during lactogenesis, describe an extracellular but intramammary change that is profound and that is critical for lactogenesis. EXPLAIN.
increase flow of blood to mammary gland and perfusion of capillaries
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name the endocrine tissues that secrete hormones that exert a direct role on mammiogenesis. for each endocrine tissue, what hormone is secreted and what aspect of mammiogenesis is affected?
- ovarian follicle, estradiol, increase ducts
- luteal cell, progesterone, increase parenchymal tissue (alveolar epithelium)
- anterior pituitary, prolactin and growth hormone, synergize with steroid hormones
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name two distinct periods of time or physiological states when managment can exert significant influence on mammiogenesis. explain each example.
- pre-puberty: if average daily gain is too high there will be too much fat accumulation.
- dry period: must not be too short to allow alveolar epithelium to replenish
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defend or refute. the mammary fat pad is a negative issue for ideal mammiogenesis. EXPLAIN.
mammary fat pad is absolutely required but must be optimal, not too thin and not too thick
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consider breeding soundness exam, what is the overall goal or purpose to conduct BSE?
to estimate potential for fertility
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for stallions excluding general physical condition name three other general factors to evaluate for a complete BSE?
- mental health
- reproductive tract
- scrotal circumference/width
- sperm morphology/motility
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in the current BSE what factors must be determined to be above threshold or above minimum to judge a male to be "satisfactory"? EXPLAIN.
- scrotal circumference/width
- spermatazoa morphology & motility
all other issues are pass/fail
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for holsteins list four issues that will affect milk yield and composition of milk. issues must affect both yield and composition. describe each issue as high/low or increasing/decreasing.
- increase age- increase yield decrease composition
- increase stage lactation- decrease yield increase composition
- dietary energy increase- increase yield decrease composition
- increase dietary fiber- decrease yield increase composition
- increase residual milk- decrease yield decrease composition
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defend or refute. variation in efficiency too harvest milk will affect composition of milk. EXPLAIN.
DEFEND. decrease efficiency (increase residual): decrease yield decrease fat (composition)
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for horse, swine, beef and dairy cattle, describe the average or typical duration for lactation. include units of measure, no ranges!!
- horse: 4 months
- swine: 3 weeks
- beef cows: 205 days
- dairy cows: 305 days
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what is the most significant consequence of mastitis? EXPLAIN.
decrease milk yield up to 40% reduction
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define somatic cell count
number somatic cells (white blood cell and antibodies) per mL of milk.
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what is the basic qualitative feature off somatic cells that allows detection and counting?
nucleus-DNA absorbs light
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what is the managerial value of somatic cell score versus somatic cell count?
SCS related linearly to decrease in milk
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describe three practices that would increase yield of fat, actual pounds, (not concentration) in caprine or bovine milk. ignore economics and focus principally on biology.
- decrease grain
- increase forage
- increase particle size of diet
- decrease residual milk
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name two managment practices for neonates that are necessary and are scheduled because of the composition of milk. EXPLAIN each.
- feeding colostrum: rich with antibodies must get to neonate prior to gut-closure
- supplemental iron to pigs
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ignore genetic potential for milk and nutritional issues, select and defend one issue as most important that affects galactopoesis. EXPLAIN.
harvest milk to keep IM pressure low to increase synthesis.
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what event or process is highly potent stimulus for lactogenesis? EXPLAIN.
Parturition, withdraw progesterone to decrease inhibin
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defend or refute. among mares, persistency is not a useful measure of lactational performance. EXPLAIN
DEFEND. lactation in mares is highly persistent
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name the constituents of milk, whether they are the result of synthetic/enzyme activity within a mammary gland. respond constituent, secretory or non secretory, and name precursor
- Casine, S, amino acids
- arachidonic acid (c-20), NS/S, Acetate
- Cortisol, NS, Choloesterol
- Prolactin, NS, amino acids
- lactose, S, glucose and galactose
- Capric acid (C-10), S, acetate.
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list three management practices that will facilitate termination of lactation of mares. for each practice named, provide a brief biological rational for the practice.
- end harvest
- decrease dietary energy
- decrease dietary water
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if there are no significant management problems, what major reason for or benefit is derived from lactational rest? EXPLAIN
replenishment of secretory cells
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defend or refute. dry periods have two phases. EXPLAIN.
REFUTE. three phases: end synthesis, apoptosis, regeneration
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define galactopoesis.
maintenance of existing lactation
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explain the galactopoetic affect of oxytocin
ejection decreases IM pressure which increases synthesis of new milk
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defend or refute. prolactin is a galactopoetic hormone because one effect is to stimulate activity of α-lactalbumin. EXPLAIN
DEFEND. increase prolactin with suckling or milking increases αlactalbumin activity
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which livestock species has the highest persistency of lactation? what is duration of lactation in this species
Horses: 3-4months
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what issues/factors determine area of lactation curve/profile
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a male fails the BSE. explain how this happened. do not describe any specific part of the complete BSE! include incidence of failure, ideal response is one sentence less than 10 words
failed to reach threshold for scrotum or sperm
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including numbers, define serving capacity for a mature angus bull.
40-50 cows in 60 days
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if cows experience synchronized estrus what is the effect of serving capacity on bulls?
increased number of heats per day-->decreased serving capacity of bull
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if a manager plans to increase the duration of the breeding period for ewes, discuss the effect on serving capacity of rams.
decreased heats per day-->decreased breedings per day-->increased serving capacity
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for all beef cows, what is the primary endocrine regulatory factor that determines duration of postpartum anovulation. EXPLAIN.
limited secretion of LHRH
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for a female to experience complete mammogenesis, what tissue must be present and develop?
- ductal
- lobular-alveolar
- inguinal fat
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name the endocrine tissues that secrete hormones that exert a direct affect on mammogenesis. for each endocrine tissue, what hormone is secreted and what aspect of mammogenesis is affected
- follicle, estradiol, ductal growth
- CL, progesterone, LA growth
- anterior pituitary, prolactin, LA growth
- anterior pituitary, GH, LA & ductal growth
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name two distinct periods of time when managment can exert significant influence on mammogenesis. EXPLAIN
- ADG too great before puberty=accumulation of too much fat
- too young or too old at first parturition
- duration of dry period too short, not enough time to regenerate alveolar epithelium
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what is the general effect of increased testicular volume on production of spermatazoa? EXPLAIN.
increase volume/capacity of seminiferous tubules=more spermatazoa
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describe endocrine regulation of the proliferative phase of spermatazoa
estradiol stimulates mitosis
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in the space between sertoli cells, where does the proliferative phase of spermatogenesis occur
basal compartment
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in the overall process of spermatogenesis, what type of cell is the first that is haploid?
secondary spermatocyte
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describe endocrine regulation of the differentiation phase of spermatogenesis
testosterone supports meiosis and metamorphosis
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defend or refute. if there are 50 million spaces between sertoli cells in a testis plus the basal and adluminal compartments, there are 100 million environments for complete spermatic cycles.
REFUTE. basal and adluminal compartments in one intercellular space is one sperm cycle or 50x106/testis or 50 million
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for horses list three factors that will affect yield of milk. use arrows to describe a change in the factor and indicate the consequent change in yield
- decrease water, decrease yield
- decrease dietary energy, decrease yield
- decrease suckling, decrease yield
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list managment practices that will facilitate terminattion of lactation. for each practice provide a bilogical rational (how does this work to end lactation)
- terminate harvest, increase pressure to decrease synthesis
- decrease water, decrease major component (milk is 80% water)
- decrease dietary energy, decrease metabolic driving force
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among species of livestock and based on current goals for production, describe when after parturition lactation is terminated. for each species named include units, no ranges.
- dairy cattle, 305 days
- sows, 28 days
- mares, 160 days
- beef cattle, 205 days
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name three major prepartum changes that must occur
- remove inhibition of myometrium, decrease progesterone
- create opening, soften cervix and relax pelvis (Relaxin)
- stimulate contractions of myometrium, increase PGF2-α
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defend or refute. swine are CL-dependant species for gestation. EXPLAIN.
DEFEND. swine need CL for progesterone entire gestation. chorion does not secrete enough Progesterone
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defend or refute. dexamethasone or cortisol will not work to induce parturition in CL-dependant species. EXPLAIN
REFUTE. if uterus produces enough PGF2 to regress CL, cortisol will decrease placental progesterone and stimulate parturition
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consider relaxin, what is endocrine cell for relaxin and what is the affect or action of relaxin?
- endocrine cell-luteal
- action-soften cervix and relax pelvis
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prolactin endocrine cascade
- dopamine from hypothalamus
- lactotrope secrete prolactin
- mammary adipose tissue
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effect of IGF-1 on mammary tissue and what mammary tissue
mammary adipose tissue, increases steroidogenic and apoptotic actions
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