Calving & Calf Management Flashcards
1
Q
What are the objectives of calving management?
A
- minimize the losses at birth
- minimize the post-natal losses
- reduce disease in calving females
2
Q
How do you calculate calf crop %?
A
number of calves weaned/number of cows exposed to bull X 100
3
Q
what is the target calf crop %?
A
85%
4
Q
What causes a reduction in calf crop?
A
- failure to conceive (infertility)
- failure to calve (abortions & stillbirth)
- failure to survive neonatal period
- failure to wean (calf mortality on pasture)
5
Q
what factors contribute to neonatal losses?
A
- DYSTOCIA
- maternal nutrition
- maternal behaviour
- climate (hypothermia)
- infectious agents & environment
6
Q
What is the impact of dystocia?
A
- 60% of preweaning mortality occurs w/in the first 96 hrs of birth
- 2/3 of these losses can be attributable to dystocia
- recent Canadian research shows that 2.7% of calves die w/in 24 hrs of birth
- calves that have higher calving difficulty are 2.4x more likely to be sick in the first 45 days of life
- calves that experience dystocia are 13 times more likely to die w/in 12 hours of birth
7
Q
who is most likely to experience dystocia?
A
- calves born to first calf heifers (5.4% of cows are assisted, 18.7% of heifers assisted, overall 7.4% of calvings are assisted)
- male calves> female calves
- twins
- calves born to cows in poor body condition
8
Q
How do we prevent dystocias?
A
- select bulls for low birth weights in calves
- birth weights account for 30-50% of the variability in dystocia rates
- use easy calving breeds esp on heifers
- use Expected Progeny Differences data on purebred bulls
9
Q
what is expected progeny differences data?
A
- breed associations report EPDS in same units as the trait they reflect
- useful for comparing bulls w/in a breed
- a bull with a birth weight EPD of +4.0 would be expected to sire calves 5 lbs heavier than a bull with a birth weight EPD if -1.0
- need to know breed average for EPD (not usually 0)
- an accuracy value (btwn 0 & 1) is usually associated w/ the EPD as a measure of it’s reliability
10
Q
What is a replacement heifer rearing program?
A
- 65% of mature weight at breeding
- 85% of mature weight at calving
- avoid over conditioning
- do not restrict nutritional intake in late gestation
- pelvic measurements are of limited value
11
Q
How does adequate surveillance and early assistance help prevent dystocias?
A
- can lead up to a 9% increase in the number of animals cycling at the onset of the breeding season & a 14% increase in the fall pregnancy rate
- early assistance increases the likelihood of a live calf
12
Q
What happens in stage 1 of calving?
A
- 3-72 hrs (cows < heifers)
- ligaments of pelvis relax
- cervix, vagina dilate
- cervical mucous plug released
- cow separates from herd
- tail raised, back arched, may start to strain
13
Q
What happens in stage 2 of calving?
A
- appearance of a water bag
- expulsion of calf through birth canal
- 30 mins to 3 hrs (cows < heifers)
14
Q
What happens in stage 3 of calving?
A
- expulsion of fetal membranes
- usually expelled w/in a few hrs of birth
- involution of uterus may take up to 40 days
15
Q
Why do we calve heifers before cows (2-3wks)?
A
- owner can concentrate workload early in calving season
- heifers are more likely to have distocia, mismother, etc.
- will calve on least contaminated calving area
- need longer to return to estrus than cows
16
Q
When should we interfere in calving?
A
- cow actively strains for 40 mins & no progress is made
- 90 mins have passed since the first waterbag appeared
- legs emerge w/ sole of the hoofs pointing up
- head or tail only emerges
- cow has demonstrated greater than 5-6 hours of anxiety (walking about, tail extended, apparently looking for something)
- uncalved cow is mothering another calf
17
Q
when should the producer call for help?
A
- calf is too big
- cant get hands alongside feet in pelvis
- cant get head & feet into pelvis at the same time (2 people using body weight only)
- heifer has been actively straining for 30 mins & cant get head & feet into birth canal
- if you cant correct the position in 20 mins or less
18
Q
What dose prolonged calving cause?
A
- calves w/ compromised vigour
- Weak calf syndrome
19
Q
Why is suckle reflex important in calves?
A
- calves w/ a weak suckle reflex had 41.6x greater odds of failing to consume colostrum by 4 hr after birth
- suckle reflex & calving ease was used in combination to predict colostrum consumption by 4 hr after birth
- consuming colostrum by 4 hr after birth positively impacted transfer of passive immunity & preweaning health of beef calves
20
Q
How do we assess the suckle reflex in calves?
A
- 10 mins after birth
- two fingers along length of the top of the calf’s tongue
- gently rub the roof of the calf’s mouth
- poor jaw tone, poor suckling rhythm = weak
- good jaw tone, good rhythm, quick strong latch = strong suckle reflex
21
Q
What are factors that contribute to neonatal losses?
A
- dystocia
- maternal behaviour
- climate/environment
- infectious agents & biosecurity
- passive transfer of immunity
22
Q
When does abnormal maternal behaviour occur?
A
- 1st calf heifers are more likely to exhibit AMB
- heifers & cows w/ dystocia are more likely to exhibit AMB
- prolonged birth is more likely to result in AMB
- less vigorous calf will also results in AMB (heifers)
- high incidences of AMB can stem from poor condition of cows
23
Q
How do we treat abnormal mothering behaviour?
A
- match the cow & calf correctly
- confinement in a box stall where there are no disturbances
- tube the calf w/ colostrum
- restrain cow regularly so calf can suck
- make sure calf is not obviously sick
- potentially fostering
24
Q
when does hypothermia occur?
A
- a calf w/in first 2-3 hrs is unable to regulate its body temp v well
- even a normal calf can become hypothermic quickly
- chilled calves will not be able to get up, suckle, & make use of colostrum
25
Q
How does climatic or seasonal effect affect calves?
A
- calves born from Dec to Mar were 4x more likely to die w/in 24 hrs of birth & 2x more likely to have D+
- WCVM data would show that calves admitted that were hypothermic are 4.3 times more likely to die
26
Q
What is our protocol for hypothermia?
A
- an electric thermometer is essential to note the severity of hypothermia
- calves < 35 C will have: cold mouth, cold limbs, no suck reflex, & unable to move limbs
- calves w/ temp > 37.8 C are considered normal
- consider using duct tape, etc. to protect ears from freezing
- calves < 35 C are considered hypothermic
- tube w/ 1-2 L of warm colostrum
- place in warm room or “hot box”
- hot water baths are essential for calves less than 26 C
- warm fluids IV, warm water enemas
27
Q
How do we decrease infection pressure?
A
- minimize confinement of the cow herd
- utilize separate wintering and calving areas
- move cows to calving area 2 wks before calving
- rotate calving area from year to year
28
Q
How to rotate calving areas in Sandhills calving system?
A
cow-calf pairs left behind, pregnant cows moved to next clean calving area
29
Q
what are other ways to decrease infection pressure?
A
- snow removal & adequate bedding
- separate nursery areas for cow-calf pairs
- avoid restricted feeding/bedding areas
- creep areas or “calf condos”
- quarantine of diarrheic calves
30
Q
How do we increase immunity?
A
- colostrum management
- vaccination
31
Q
How is immunity transferred passively?
A
- the bovine placenta has a syndesmochorial placentation that doesnt permit the passage of Ig from the maternal to fetal circulation
- the newborn calf is born w/ no maternal Abs & must rely on adequate & immediate intake of colostrum to receive passive immunity
32
Q
What is the timing of ingestion of passive immunity?
A
- newborn enterocytes can absorb macromolecules like Ig until approximately 24 hrs of life
- however, absorption is optimum in the first 4 hrs of life
- absorption capacity begins to decline rapidly after 12 hrs of life
33
Q
what is the cutoff level for adequate colostrum?
A
> 24 g/dl
34
Q
how do we measure passive transfer?
A
- blood sample from a calf btwn 1-7 days of age
- radial immunodiffusion is gold standard
- total serum protein is measured by refractometer or Brix refractometer can be used as a surrogate for RID
- turbidity test using sodium sulfite or zinc sulfate can be used for qualitative assessment
35
Q
How do we manage colostrum?
A
- a calf needs a minimum of 1-2 L of colostrum w/in 4 hrs of birth
- beef cow colostrum contains 150 g of IgG/L on avg (compared to 64 g for dairy cows)
- gut closure begins at 6 hrs & continues until 24-36 hrs
- calves need 80-150g of Ig (1-2 L) colostrum
- normal calves will drink btwn 1-2 L/feeding
36
Q
what are intervention strategies?
A
- focus on high risk groups: dystocias, mismotherings, hypothermias, bad udders
- milk dam if possible & force feed colostrum to calf
- use colostrum saved from other calvings as 2nd choice
- use a good colostrum replacer as an alternative when necessary
- avoid buying colostrum from dairies
- any cows that are handled should be milked out
- save this colostrum to top up calvings where the dam cant supply sufficient colostrum
- fresh colostrum should be stored in ziplocked bags laid flat
- fresh colostrum can last 7-10 days in the refrigerator
- thaw in a warm water bath only
- all calves that havent suckled w/in 2-3 hrs should be noted
- in cold weather, action may need to be taken sooner
- on warm days, give the pair more time
- assume all abandoned calves have not suckled
37
Q
how do we enhance specific immunity?
A
- vaccination of dam pre-calving
- E coli & rota/corona virus vaccines
- 6 wks & 2 wks pre-calving (some vaccines have slightly different timing claims)
- colostrum management is still important
