Replacement Heifers

Question 1

In which system (beef vs dairy) is the timing of calving more important?

Answer 1

BEEF

Question 2

In which system (beef vs dairy) is it easier to address nutrition for a subset of animals?

Answer 2

DAIRY

Question 3

Compare and contrast first calf heifers to replacement heifers.

Answer 3

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

Question 3

Why are the nutrient demands pre-calving and post calving for the 1st calf heifer more intense than any other stage of production?

Answer 3

Precalving they are both growing and gestating, and post calving they are both growing and lactating

Question 4

How long do 1st calf heifers need for postpartum anestrus compared to cows?

Answer 4

100 days vs 70 days

Question 5

Which should you breed first- heifers or cows?

Answer 5

Heifers! They take longer to recover post-calving so breeding them early will help with synching them with the rest of the herd

Question 6

What is the goal for when a 1st calf heifer should give birth for the first time?

Answer 6

22-23 months

Question 7

What is a good way to shorten post partum anestrus in primiparous heifers?

Answer 7

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

Question 8

Describe the benefits of calving at 2 years vs 3?

Answer 8

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

Question 9

What are the benefits to calving in the first 21 days of the season?

Answer 9

Increased longevity in the herd, increased calf weaning weights in the first 6 years, increased pregnancy rate for the first 4 years

Question 10

Define puberty in heifers

Answer 10

Ovulation accompanied by visual signs of estrus followed by a luteal function of a normal length

Question 11

When is the ideal time to breed a heifer in order to maximize fertility?

Answer 11

At her 3rd cycle

Question 12

When should you start breeding cows to maximize the amount calving early?

Answer 12

13 months (on second estrus)

Question 13

What are some of the mechanisms controlling puberty?

Answer 13

Genetics, weight, hormonal regulation

Question 14

What is the goal weight for heifers at breeding?

Answer 14

65%

Question 15

What type of cows is it better to breed at 55%

Answer 15

Crossbred, earlier maturing breeds, moderately framed cows, large herds, limited forage

Question 16

T/F: higher weaning weights are associated with younger age/heavier weight at puberty

Answer 16

T

Question 17

What is the average daily gain recommended to reach puberty at 13 months?

Answer 17

1.1-1.7 lb/day

Question 18

When should you perform a pre-breeding exam?

Answer 18

30-60 days prior to breeding
- shorter for more accurate cycling/size, longer if you want more time to correct weight

Question 19

What is the purpose of pelvimetry?

Answer 19

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

Question 20

What are the things you should do when breeding heifers to make them easier to breed the next year?

Answer 20

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

Question 21

What are the pros and cons to raising replacements?

Answer 21

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

Question 22

What are the pros and cons to buying replacements?

Answer 22

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

Question 23

What are the negative outcomes associated with FPT?

Answer 23

Increased preweaning mortality and morbidity, decreased growth/ADG, decreased milk production in 1st lactation, increased culling rates through first lactation