Nutri Girls Test Flashcards
Growth rate for heifers
0.7kg/d
% MLW for puberty
35-45%
How many days and what weight do we wean at?
240d around 200kg
weigh at weaning and compare with target critical mating weight and see who will make it
What is critical mating weight?
The average weight a group of heifers would achieve 85% conception from a 45d mating
60-65% MLW
British breeds = 280-320kg, bos indicus 300-320kg
What age do we want heifers calving by?
2 years (join at 15 months)
Conception rate for 42 days (2 cycles)
96% (we lose 30% of these and come back to 65% pregnant)
3 cycle joining period calving rate
95 in 63 days
How many cows should be pregnant on first cycle?
65%
First date for ultrasounding heifers
22-35d after joining
Pregnancy nutrition MJME
8.5-9.5MJME/kg DM
may need to increase to 10 in last 2 months gestation
Birth to weaning LW gain
1kg/d
Lactating MJME
more than 10.5MJME
Reasons for dystocia
- Foetal malpresentation (should be anterior)
- Foetal size
- Maternal pelvis conformation
- Uterine inertia - lack of contractions
- Insufficient dilatation of cervix and uterine torson
risk factors for dystocia
Breed
Age - primiparous heifers highest risk
Nutrition - under or over (more fat in pelvic area, smaller pelvic inlet or under nutritioned heifer wont have enough energy to deliver calf
Genetics -> live birth weight and calving ease are inherited
Methods of investigation for dystocia
- Clinical exam (palpation of birth canal and calf position)
- Ultrasound for size and position
- Labour monitoring for strength and frequency of contractions (intervene if struggling for more than 2 hours)
Prevention and control strategies for dystocia
Selective breeding -> lower birth weight calves
Nutrition
Regular monitoring -> detect pregnancy abnormalities throughout
Assist calf early
Bulls -> good ebvs
Cull cows with dystocia previously
Purpose and Process of reproductive tract scoring
Purpose -> to determine if the repro tract is able to carry a pregnancy, done at puberty and cyclicity development
45-60d prior to breeding >50% of heifers should be a score 4-5
Process -> Assesses uterine horns and ovaries by measurements (diameter, length, height, width) and any follicles or tone
Process of pelvimetry
Measurement of pelvic dimensions to assess the risk of potential obstruction
Describe heterosis in heifers
The production advantage from crossing breeds
Offspring have better production values than their parents
BVDV AGID Test process
Agar gel Immunodiffusion assay
Used to measure seroprevalence + detect recent infection (especially within last 9 months)
Test will detect antibody (Ab) from at least several years before Ab reaction measured and quantified:
negative = susceptible animal
1 or 2 (weekly positive/positive) = exposure to BVDV less likely to have happened within the last 12 months
≥3 (strongly or very strongly positive) = recent infection, usually in the last 3-9 months
Samples from pregnant females that yield this result indicate the female may be carrying a PI foetus
What age do heifers begin cycling?
9-15 months
Puberty is at 35-45% MLW
Gestation length of cows
280d
Calving to first heat interval length
55d
How many MJ does it take to grow 1kg?
35MJ ME
Bacterial causes of abortion
Leptospirosis (hardjo) - spirochete aquatic and zoonotic
Campylobacter
Brucellosis
Trueperella pyogenes
Mycoplasma
Ureaplasma
Viral causes of abortion
BVDV