Lecture 5+6 Flashcards
(131 cards)
1
Q
How long does proestrus last
A
2 days
2
Q
How long does estrus last
A
14-18hrs
3
Q
How long is metestrus
A
3 days
4
Q
What is diestrus
A
Period of corpus luteum, where it produces progesterone and is functional for 17 days of the cycle
5
Q
When does ovulation occur and what triggers it
A
Ovulation is spontaneous and occurs 12-14hrs after the end of estrus
6
Q
Describe the reproductive anatomy of the female heifer
A
Heifers: uterus lies within the pelvic canal
7
Q
Describes the reproductive anatomy of the female older cow
A
The uterus falls into the abdominal cavity quickly once pregnant.
8
Q
What happens to sperm production to the bull in the summer
A
They produce sperm throughout the year, but a decline in numbers once the summer occurs
9
Q
What three factors influence puberty
A
Nutrition
Breed
Sex
10
Q
When is puberty in female reached
A
When the first external signs of estrus occur
11
Q
When do tests descend in the male
A
They decend into the scrotum at birth.
12
Q
When does testicular tissue differentiate
A
3-4 months
13
Q
When is the male considered fertile
A
At 8-10 months
14
Q
When is a male in puberty
A
7-20 months
15
Q
How often will a cow show estrus, and when will it stop
A
Cow will show estrus at approximately every 21 days. Until the age of 10-12
16
Q
When does postpartum anesteus occur
A
For 30-50 days following the birth of the cow and many will have silent estrus at first.
17
Q
When will the cows uterus be adapted to another pregnancy
A
40 days post partum and ideally the calving to calving interval is 12-13 months. (9 months gestation, 3 months to get her pregnant again)
18
Q
When are cows more fertile
A
In the spring
19
Q
How many fertile ova will a cow produce in her full reproductive cycle
A
50 fertile ova
20
Q
How is proestrus characterized
A
By follicular growth and estradiol production, causing edema of the genital tract. Vulvular secretion is seen. The cows group together
21
Q
What hormones will be released during proestrus
A
FSH stimulation
22
Q
What type of breeding cycle do cows have
A
Polyestrous nonseasonal breeders with estrus occurring at an average interval of 21 days
23
Q
What behaviour is seen in proestrus
A
Cows group together, moves around more, less attracted to feed, sniff others, allow themselves to be sniffed, bellows, but will not stand.
24
Q
What is estrus
A
The period of sexual receptivity is a result of estradiol acting on the CNS.
25
How long does estrus last
Lasts 14-18 hours,
26
What are the clinical signs of estrus
swollen redden vulva, clear stringy mucous discharge.
27
What is the behaviour of the cow in estrus
The cow becomes passive, calm, allows mounting and mounts other cows.
28
What does the surge of LH do in the cow
LH stimulates the mature follicle to ovulate.
| She is restless, anxious, inappetant, bellows.
29
How would you describe the cows period of receptivity
Cow is different from most with such a short period of receptivity
30
When does ovulation occur in a cow
ovulation occurs 12-16 hours after the end of estrus.
31
What are 5 reasons why poor heat detection occurs
1. Not enough time is spent
2. Most mounting activity occurs at night in loosely housed herds
3. Heat period is short
4. Mounting lasts 10 seconds
5. Feet and leg problems with slippery floors, reduces visibility
32
What are 7 estrus detection aids
1. Wall charts, breeding wheels, herd monitors and individual records
2. Secondary signs of heat (vulva and mucous discharge)
3. Mount detection aids – these are pressure-sensitive devices that change color to detect mounting
4. Palpation of organs by a vet
5. Heat detector animals (hormonally treated cows, penile deviation bulls with markers)
6. Heat synchronization – using prostaglandins, if they have a functional CL, with be in heat in 2-7 days
7. Pedometers on cows – to measure activity levels
33
What is metestrus
The time following cessation of heat, where ovulation occurs, and luteal cells begin to develop.
34
What biological changes occur in metestrus
Congestion of the genital tract diminishes, and the glandular secretions decrease, some pseudomenstruation occurs (seen as bloody discharge, only in 50% cows, 90 % heifers).
35
What behaviour changes occur in metestrus
The cow will no longer accept mounting
36
What happens to the ovulated egg in metestrus
The ovulated egg is picked up and transported toward the uterus, with fertilization occurring at this time.
Whether fertile or not, enters the uterus 3-4 days post-ovulation.
37
What is diestrus
Period of a functional CL, whether the cow is pregnant or not.
38
What body parts are affected in diestrus
Mammary development and uterine growth affected.
39
What happens if the zygote meets the uterus
If the zygote reaches the uterus, the CL stays, if not, then CL regresses on day 17.
40
What behaviour changes occur when the cow is pregnant
If pregnant, cow may still smell and mount other cows in heat, so must be careful not to inseminate again.
41
What does the CL's creation of progesterone trigger
The CL production of progesterone prepares the uterus to nourish the fertilized egg. If fetus is not there, prostaglandin is released by the uterus and causes regression of the CL.
42
How long does estrogen dominate in the cycle
Estrogen dominates 4 days of the cycle
43
How long does progesterone dominate in the cycle
progesterone 17 days
44
What is the fertilization time of cows
Fertilization time is complicated because the cow ovulates 12-15 hours after the end of estrus, fertility being highest in the midheat or end of heat, and declines very quickly.
Sperm reach the site of fertilization very quickly, but need to capacitate in the female tract before fertilization, with peak fertility being 7-18 hours before ovulation, hence during the heat period.
45
How long can sperm age and maintain fertility
Although sperm can age 18-20 hours and maintain fertility,
46
How long can ova age and maintain fertility
ova cannot age more than 4-6 hours.
47
What are cows who cannot get pregnant after 3 inseminations called
repeat breeders.
48
What happens if a cow cycles more than every 21 days
If they cycle more than every 21 days, we say it is likely early embryonic death (EED)
49
What happens if a cow cycles less than every 21 days
and if less than 21 days, cystic ovaries.
50
What does the appropriate artificial insemination time depend on
The time of egg release (10-12 hours after standing heat)
Lifespan of the egg (6 hours)
Capacitation of sperm (5-6 hours)
Life span of sperm
51
What are the three general groups of ovarian dysfunction
anestrus, silent or quiet estrus, cystic ovaries.
52
What causes anestrus
stress of animal, disease, climate, nutrition, lactation may cause an anestrus.
53
What is anestrus treated with
Treated with pituitary gonatrophins, especially FSH.
54
What can a cystic ovarian metritis be corrected with
1. Enucleation rectally
| 2. Hormones injection
55
What is a silent estrus
shortage of estrogen, but ovulation does occur. If inseminated, will conceive.
56
What are cystic ovaries
another form of COD is where follicular cysts develop, accumulate a lot of fluid, and do not proceed to ovulation.
The cows can present in frequent heats, and nymphomaniac tendencies, or irregular or no heat.
Again, hCG is the treatment of choice, or manual rupture.
57
What changes with uterine tone if a cow is pregnant
Since uterine tone is a good indicator of estrus and can be detected by rectal palpation, it is used by most inseminators to verify if cows submitted for insemination are in estrus.
58
What does estrus do to the endometrium
Estrogen increases the vascular growth of the endometrium. When withdrawn (following ovulation), hemorrhages in the endometrium causes blood in the vulvar discharge. So some cows show bleeding on the second or third day after estrus.
59
How do you determine sperm production
Sperm production, fertile sperm is correlated to testicular size, which can be estimated by the length and width of scrotal circumference.
60
How much semen do bulls ejaculate
Bulls ejaculate 4-10 ml of semen, containing 800 million or 2000 million (2 billion) sperm per milliliter.
Sperm increases with the age of the bull up to 7 years, and then declines.
61
Describe the penis of the bull
Penis is fibroelastic, small diameter, rigid when no erect.
Protrusion occurs by straightening of the S-shaped sigmoid flexure. cows respond to chin-resting by standing.
Mating is brief, less than 5 seconds
62
Where is the progesterone required to maintain pregnancy in the cow made
The ovary is the major source of progesterone needed to maintain pregnancy in the cow.
63
What does fetal cortisol trigger
Fetal cortisol triggers parturition, stimulating the conversion of progesterone to estrogen and also causing a release of uterine PGF2, causing the terminating luteal function.
64
How long is gestation in a cow
Gestation is 276-295 days, average 285 or 9 months.
65
What are the biological changes of the vagina when the cow is close to parturition
Nearing parturition, the vulva discharges a thick and stringy mucus, the udder enlarges, and the teats become distended (with colostrum).
66
Describe the cows behaviour the day before parturition
1-2 days before calving, the cow is restless, keeps a small isolated area, and defends it. She should be placed in a clean, disinfected maternity pen, with a non-slippery floor, lots of bedding and good ventilation.
67
What does the cow do during stage 2 of parturition
Stage II is done either lying down, standing or sternal, with abdominal straining. The amnios appears at the vulva (water bag) and the calf soon follows.
68
How long does it take for the calves to stand
Calves take 45 minutes to stand and a few hours to suckle.
69
How many stages are in parturition
```
3 stages as in all species
Stage 1- dilation, nervousness, and nesting
Stage 2- pushing
Normal parturition
Stage 3- placenta
```
70
What is the first stage of parturition
Dilation, nervousness, nesting
71
What is the second stage of parturition
Pushing
72
What is the third stage of parturition
Placenta
73
When is colostrum released
colostrum within the first 2-12 hours, separate from the dam within 24 hours into an individual pen, feeding whole milk.
74
When are cows weaned
Weaning occurs 5-6 weeks,
75
When is roughage introduced to a baby cow
at 3 weeks
76
When is grain fed until
Grain is fed until 12 months.
77
When are cows dehorned, vaccinated and castrated
Calves are dehorned, castrated, vaccinated at 2-3 months (extra surgeries such as supernumerary teats treated and umbilical hernias).
78
When are heifers bred
Heifers are bred when they reach a good weight, usually at 14-15 months, with the first parturition and milk production starting at 24 months.
79
When do beef cattle usually calve
Beef cattle usually calve over 45 days from March to April.
80
What happens in May if the calves were done in march or april
At the end of May, branding, dehorning, vaccination, deworming occurs.
81
When are cows generally weaned
October
82
When are bulls placed with the female
Bulls placed with the female from June to July 15 in order to achieve calves from a same age group to regroup them in the same feedlot. Unbred cows are culled.
83
How often are twins born in dairy breeds
Twins are born in about 2% of births in dairy breeds,
84
How often are twins born in beef cattle
and 0.4 % in beef, and result in dystocia
85
What also causes dystocia
Dystocia is caused also by fetal malpresentations.
86
What are freemartins
Freemartins are the mixing of male and female twin, which causes the female to be androgenized.
87
What is the postpartum period
The postpartum period is the time following parturition during which lactation is initiated and reproductive cycles are re-established.
88
What occurs in the uterus in the postpartum period
The uterus undergoes involution, the gravid horn is larger and the muscle tone gradually returns to cause shrinking.
89
How many days after the postpartum period are dairy cows usually bred
Dairy cows are bred usually 50 days after postpartum, and should conceive by 80 days in order to maintain a calving interval on 12 months.
90
What is the purpose of examining the reproductive tract
diagnosis of pregnancy,
estimation of gestational age,
characterization of the reproductive status.
91
What do you need to know about the animal in order to evaluate the reproductive tract
a. virgin cow, pregnant heifer, uniparous/multiparous
b. age
c. cycle history
d. calving dates and comments
e. breeding dates and methods
f. previous treatments
g. nutritional program
92
How do we perform the examination of the reproductive tract
The method of physical examination is best by rectal palpation of the cervix, uterus, ovaries and other supporting structures.
93
Describe the feeling of the follicle
Follicles – have a smooth outline, with fluctuation below the surface
94
Describe the feeling of the CL
CL’s – soft and crepitate following ovulation, to a liverlike consistency at midcycle, to a firm structure at the end of the luteal, many have a papilla.
95
Describe the feeling of the CA
Corpora albicans – (what is it?) small and firm, really scar tissue
96
Describe what smooth ovaries indicate
Smooth ovaries – with no significant structures, indicates a cow is not cycling
97
What do you find in the absence of a CL
Ovarian cysts- fluid filled structures greater than 25 mm diameter, found in the absence of a detectable CL.
98
What % of animals that are pregnant exhibit estrus
Cessation of estrus is not a reliable sign, because 10 % of pregnant cows exhibit estrus, and also can be caused by pathological problems.
99
What is the membrane slip
membrane slip – chorioallantois slips through uterine horns, at 30 days of pregnancy
100
What is the amniotic vesicle
amniotic vesicle – as a moveable object within the uterine lumen from 30-65 days
101
What is a placentome
placentomes – detected as soft thickened bumps in the uterine wall from 75 days on (type of placenta??)
102
At what time can you palpate the fetus
palpation of fetus – 65days to term
103
At what point can you palpate the uterine artery fremitus
uterine artery fremitus – from 120 days, the fremitus is unilateral (which side?), at 7 months it is bilateral
104
What methods during the examination allow you to know if the animal is pregnant.
Methods are:
membrane slip – chorioallantois slips through uterine horns, at 30 days of pregnancy
amniotic vesicle – as a moveable object within the uterine lumen from 30-65 days
placentomes – detected as soft thickened bumps in the uterine wall from 75 days on (type of placenta??)
palpation of fetus – 65days to term
uterine artery fremitus – from 120 days, the fremitus is unilateral (which side?), at 7 months it is bilateral
105
What is vaginoscopy show
Vaginoscopy, using a cylindrical speculum and a penlight.
The secretions indicate the stage of the estrus cycle.
Large quantities of stringy water-clear mucus indicate proestrus; small amounts of blood indicate metestrus; and diestrus, mucosa is pale with scanty sticky mucus.
106
What are the other methods of vaginal evaluation
Laparoscopy
Ultrasound
Milk progesterone or plasma progesterone assays – elevated after 24 days post breeding, strongly suggest pregnancy, accuracy 80% for pregnancy, 100% non pregnant
107
What results in 15% of reproductive wastage
Failure of fertilization accounts for 15% of reproductive wastage.
108
What results in 25% of reproductive wastage
Embryo loss accounts another major portion of reproductive wastage (25%).
109
What does early embryo loss cause
Early embryo loss results in a normal cycle, late embryo loss manifests in late and irregular returns to heat.
110
What can early embryo loss be secondary to
EED can be 2ndary to nutritional deficiencies, cytogenic abnormalities, immunological factors, uterine environment, and bad timing of insemination.
111
How do you induce abortion in an animal
Induced abortion
Pregnancy maintenance is dependent on adequate concentration of circulating blood progesterone.
In order to terminate pregnancy, one needs to eliminate the source of progesterone.
The CL is the main source of progesterone for the first 5 months, and the last month PGF2 results in luteolysis.
112
What do glucorticoids cause when given with PGF2 in a pregnant cow
Glucorticoids reduce placental secretion of progesterone, so a combination of steroids and PGF2 can induce abortion between the 5-8 months of gestation.
Estrogen is also luteolytic.
113
When do we do a caesarian sections occur
Done when there is fetal malpresentation
Breech, butt first, most common malpresentation
Can try to manipulate them, but often easier to just do C-section
114
What happens when a calf is dead
When calf is dead, sometimes need to do a fetotomy
| Use embryotomy wire (gigli)
115
What are the reasons to induce abortions
Reasons to induce abortions are
a prevent dystocia after mismating heifers
b. unintentional breeding to an undesirable bull
c. pregnancy of feedlot heifers reduces feed efficiency
d. pathological diseases of pregnancy- “hydrops”
e. prolonged gestation – dead fetus, mummies, hydrocephalus, anencephaly
116
What is Hydroallantois/hydroamnios
Hydroallantois and hydroamnios: rapid accumulation of fluid in late gestation following an abnormal function of the placentomes. Results in a distended, tense abdomen with anorexia, dehydration and dyspnea.
117
When does Fetal mummification and fetal maceration occurs
occurs when a fetus dies without luteolysis and cervical dilatation for expulsion.
Mummification occurs from the 3rd to 8th month of gestation.
Maceration occurs at any stage, with chronic, mucopurulent discharge from the vulva.
118
What can cause metritis
Unsanitary calving conditions can increase bacteria, causes uterine infection.
Retained placentas are also associated with increased metritis, as well as excessive manipulation of genital tract and trauma during calving.
Mixed populations of bacteria are always present, and if conditions are favorable, they can cause life threatening septic, toxic or gangrenous metritis.
119
What happens if ovulation occurs before the uterus has expelled the exudate
If ovulation occurs before the uterus has expelled the exudate, the CL is retained, the cycle is interrupted and pyometra may be perpetuated.
120
What is the treatment for pyometra
Treatment is with antibiotics, and with prostaglandins.
121
What is a retained placenta related to
```
metabolic disease
infections
uterine inertia
dystocia
stress
nutrition
hormonal problems
hereditary factors
```
122
What is considered a retained placenta
Placenta is kept longer than 12 hours, where a disturbance of the loosening mechanism of the placentomes is affected.
123
What is the treatment for a retained placenta
Oxytocin and observation, sometimes place intra-uterine antibiotics or douches
Manual removal of placenta
Placentome removal
124
Describe cystic ovaries
Follicle like ovarian structures, persist more than 10 days, incidence is 10-30%.`
125
What are the causes of cystic ovaries
```
Causes:
Season
Age
level of milk production
hereditary factors
nutrition
Ovarian dysfunction results, with either anestrus (80%) or nymphomania (20%).
```
126
What is Obturator paralysis
Happens when the fetus is big and stays too long in the birth canal, crushing the obturator nerve on the ilium.
This causes paralysis of the adductor muscles, and the cow cannot stand.
127
What is milk fever
Hypocalcemia that happens usually in the early stages of lactation The animal cannot absorb adequate calcium to meet lactational needs, so uses serum calcium. A flaccid paralysis and inability to rise are observed.
128
What is ketosis
A metabolic disorder where the body cannot produce enough sugar for energy requirements. Then, the fat stores are used resulting in ketones production, the by-product of fat metabolism. These are toxic, cause anorexic, and a characteristic “sweet smelling”, slightly alcoholic breath.
Ketone bodies can be picked up in the urine, and this is called ketonuria (look at the dip stick).
129
What is mastitis
Common problem, usually due to inappropriate conditions, cleanliness, pump pressure.
Milk must be removed from affected quarters.
Good hygiene in the milking parlour helps
Somatic cell counts are used to evaluate neutrophils count, done on all quarters.
130
What is a prolapsed uterus
The cow keeps straining, and the uterus everts out of the vulva. It must be replaced back in with an epidural anesthetic after cleaning.
Sometimes bladder comes out as well.
131
What is Perineal lacerations
Occur when cow has pushed too hard.
