Calving & Calf Management

Question 1

What are the objectives of calving management?

Answer 1

• minimize the losses at birth
• minimize the post-natal losses
• reduce disease in calving females

Question 2

How do you calculate calf crop %?

Answer 2

number of calves weaned/number of cows exposed to bull X 100

Question 3

what is the target calf crop %?

Answer 3

85%

Question 4

What causes a reduction in calf crop?

Answer 4

• failure to conceive (infertility)
• failure to calve (abortions & stillbirth)
• failure to survive neonatal period
• failure to wean (calf mortality on pasture)

Question 5

what factors contribute to neonatal losses?

Answer 5

• DYSTOCIA
• maternal nutrition
• maternal behaviour
• climate (hypothermia)
• infectious agents & environment

Question 6

What is the impact of dystocia?

Answer 6

• 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

Question 7

who is most likely to experience dystocia?

Answer 7

• 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

Question 8

How do we prevent dystocias?

Answer 8

• 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

Question 9

what is expected progeny differences data?

Answer 9

• 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

Question 10

What is a replacement heifer rearing program?

Answer 10

• 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

Question 11

How does adequate surveillance and early assistance help prevent dystocias?

Answer 11

• 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

Question 12

What happens in stage 1 of calving?

Answer 12

• 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

Question 13

What happens in stage 2 of calving?

Answer 13

• appearance of a water bag
• expulsion of calf through birth canal
• 30 mins to 3 hrs (cows < heifers)

Question 14

What happens in stage 3 of calving?

Answer 14

• expulsion of fetal membranes
• usually expelled w/in a few hrs of birth
• involution of uterus may take up to 40 days

Question 15

Why do we calve heifers before cows (2-3wks)?

Answer 15

• 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

Question 16

When should we interfere in calving?

Answer 16

• 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

Question 17

when should the producer call for help?

Answer 17

• 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

Question 18

What dose prolonged calving cause?

Answer 18

• calves w/ compromised vigour
• Weak calf syndrome

Question 19

Why is suckle reflex important in calves?

Answer 19

• 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

Question 20

How do we assess the suckle reflex in calves?

Answer 20

• 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

Question 21

What are factors that contribute to neonatal losses?

Answer 21

• dystocia
• maternal behaviour
• climate/environment
• infectious agents & biosecurity
• passive transfer of immunity

Question 22

When does abnormal maternal behaviour occur?

Answer 22

• 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

Question 23

How do we treat abnormal mothering behaviour?

Answer 23

• 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

Question 24

when does hypothermia occur?

Answer 24

• 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

Question 25

How does climatic or seasonal effect affect calves?

Answer 25

• 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

Question 26

What is our protocol for hypothermia?

Answer 26

• 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

Question 27

How do we decrease infection pressure?

Answer 27

• 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

Question 28

How to rotate calving areas in Sandhills calving system?

Answer 28

cow-calf pairs left behind, pregnant cows moved to next clean calving area

Question 29

what are other ways to decrease infection pressure?

Answer 29

• 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

Question 30

How do we increase immunity?

Answer 30

• colostrum management
• vaccination

Question 31

How is immunity transferred passively?

Answer 31

• 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

Question 32

What is the timing of ingestion of passive immunity?

Answer 32

• 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

Question 33

what is the cutoff level for adequate colostrum?

Answer 33

> 24 g/dl

Question 34

how do we measure passive transfer?

Answer 34

• 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

Question 35

How do we manage colostrum?

Answer 35

• 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

Question 36

what are intervention strategies?

Answer 36

• 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

Question 37

how do we enhance specific immunity?

Answer 37

• 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