Replacement Heifers Flashcards
In which system (beef vs dairy) is the timing of calving more important?
BEEF
In which system (beef vs dairy) is it easier to address nutrition for a subset of animals?
DAIRY
Compare and contrast first calf heifers to replacement heifers.
1st calf heifers are those who have been bred once and you are working on breeding them back vs replacement heifers are those new to the herd or being introduced to the herd to try to improve genetics, but they have not given birth yet
Why are the nutrient demands pre-calving and post calving for the 1st calf heifer more intense than any other stage of production?
Precalving they are both growing and gestating, and post calving they are both growing and lactating
How long do 1st calf heifers need for postpartum anestrus compared to cows?
100 days vs 70 days
Which should you breed first- heifers or cows?
Heifers! They take longer to recover post-calving so breeding them early will help with synching them with the rest of the herd
What is the goal for when a 1st calf heifer should give birth for the first time?
22-23 months
What is a good way to shorten post partum anestrus in primiparous heifers?
Increase their BCS
- supplement their feeding to make sure they will calve in at BCS of 6
-continue to supplement them post-partum
-can also remove calves for 48 hours, introduce bull sooner, or use exogenous hormones
Describe the benefits of calving at 2 years vs 3?
Production of 0.7 calves more by 6.5 years of age
-500$/cow increase in return at 6.5 years
-138 kg more weaned calf over lifetime
-6-8% more repro efficiency
What are the benefits to calving in the first 21 days of the season?
Increased longevity in the herd, increased calf weaning weights in the first 6 years, increased pregnancy rate for the first 4 years
Define puberty in heifers
Ovulation accompanied by visual signs of estrus followed by a luteal function of a normal length
When is the ideal time to breed a heifer in order to maximize fertility?
At her 3rd cycle
When should you start breeding cows to maximize the amount calving early?
13 months (on second estrus)
What are some of the mechanisms controlling puberty?
Genetics, weight, hormonal regulation
What is the goal weight for heifers at breeding?
65%
What type of cows is it better to breed at 55%
Crossbred, earlier maturing breeds, moderately framed cows, large herds, limited forage
T/F: higher weaning weights are associated with younger age/heavier weight at puberty
T
What is the average daily gain recommended to reach puberty at 13 months?
1.1-1.7 lb/day
When should you perform a pre-breeding exam?
30-60 days prior to breeding
- shorter for more accurate cycling/size, longer if you want more time to correct weight
What is the purpose of pelvimetry?
Measuring the size of the area of the pelvis to reduce the risk of calving difficulties- breed for larger pelvic size
-minimum usually 130 cm^2
What are the things you should do when breeding heifers to make them easier to breed the next year?
Breed 6 weeks earlier, shorten breeding season to 30-45 days and cull those who do not become pregnant, use hormones to increase the number that concieve early, synchronize and AI heifers, supplement nutrition
What are the pros and cons to raising replacements?
Pros: decreased biosecurity risk, can cultivate genetics, no stress of moving, more economical for large herds
Cons: increased bull management, intensive management of heifers from weaning to breeding
What are the pros and cons to buying replacements?
Pros: improve cow genetics quickly, less complicated bull management, more economical for small herds
Cons: increased biosecurity risk, stress from moving, have to be sure heifers were well managed
What are the negative outcomes associated with FPT?
Increased preweaning mortality and morbidity, decreased growth/ADG, decreased milk production in 1st lactation, increased culling rates through first lactation
