Dairy Production: Life Cycle of a Replacement Heifer

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Questions and Answers

What percentage of calves are born in spring in a dairy herd?

70%

60%

90%

80% (correct)

How is a calf's airway cleared after birth?

Cow licks the calf

Farmer uses iodine solution

Cow is rubbed vigorously

All of the above (correct)

What is the primary reason for artificial rearing of calves in dairy farming?

To improve calf health

To increase milk production

To reduce labor costs

To prevent loss of milk (correct)

Why can't a calf digest concentrate ration at an early age?

Its rumen is not fully developed Signup and view all the answers

What is the sequence of feeds for a calf?

Colostrum, Natural Milk, Milk Replacer, Concentrate ration Signup and view all the answers

What is colostrum also known as?

Beestings Signup and view all the answers

What is the duration of gestation in dairy cows?

283 days Signup and view all the answers

Why is colostrum important for a calf?

All of the above Signup and view all the answers

What is the recommended Body Condition Score (BCS) for heifers at mating?

3.25 Signup and view all the answers

Why are older cows culled from the herd?

To improve the genetic merit of the herd Signup and view all the answers

What is the purpose of dosing for hoose in overwintering?

To reduce parasite infestation Signup and view all the answers

What is the target weight for heifers at breeding?

300-330kg Signup and view all the answers

What is the recommended rate of live weight gain (LWG) for heifers?

0.6-0.7kg per day Signup and view all the answers

What is the purpose of feeding good quality silage with a DMD of 75% to overwintering heifers?

To improve feed digestion Signup and view all the answers

What is the percentage of protein in fresh milk?

3.2% Signup and view all the answers

Why should calves be fed colostrum?

Because it provides immunoglobins to the calf Signup and view all the answers

What is the purpose of introducing concentrates and hay to calves?

To develop the rumen microflora Signup and view all the answers

What is a key benefit of grazing calves in a leader-follower system?

Improved live weight gain Signup and view all the answers

What is the purpose of ear tagging in calf management?

To identify calves with BVD Signup and view all the answers

What should be a key feature of a calf shed?

Clean, well-ventilated, and draught-free conditions Signup and view all the answers

What is the advantage of feeding calves fresh, palatable grass?

It reduces the risk of disease transmission Signup and view all the answers

What is the purpose of milk replacer in calf management?

To provide a more cost-effective alternative to fresh milk Signup and view all the answers

Study Notes

Life Cycle of a Replacement Heifer: Birth to 2 Years

80% of calves are born in spring, and all calves born in a dairy herd are artificially reared.
Gestation length is 283 days (9.5 months), and cows are mated in April.
Before producing milk, cows need to produce a calf, which requires a series of steps after birth:
- Clearing airways of mucus
- Stimulation of circulation through licking or rubbing
- Disinfecting nasals with iodine solution
- Feeding 2-3 liters of colostrum

Calf Rearing

In dairy farming, all rearing is done artificially to avoid milk loss.
Calves are reared for two main reasons:
- As replacements for the dairy herd
- For beef production
Calves cannot digest concentrate ration at an early age due to an underdeveloped rumen.
The normal feeding sequence is:
- Colostrum
- Natural Milk
- Milk Replacer
- Concentrate ration/Hay/Grass

Colostrum

Produced for 4-5 days after birth, also known as beestings
Creamy and dark in color, high in nutrients and antibodies, providing passive immunity to the calf
Composition:
- Water: 78%
- Solids: 22%
- Protein: 14.9%
- Fat: 6.7%
- Lactose: 2.5%
- Vitamins and Minerals: 1.2%
- Immunoglobins: 6.0%

Milk Replacer

A powdered milk mixed with water
Fed to calves after receiving colostrum, with regular feeding times to avoid scour
Calves have access to hay, concentrates, and fresh water to develop the rumen

Concentrates/Hay/Grass

Gradually introduced to develop the rumen microflora, referred to as 'scratch factor'

Ear Tagging and BVD

Bovine Viral Diarrhoea (BVD) is a virus, and animals with this virus must be identified and culled

Housing

Calves' shed should be:
- Clean, well ventilated, and draught-free
- Have clean bedding
- Access to fresh water
- Cleaned out regularly

Weaning

Calves are selective grazers and should graze in a Leader-follower system
Fresh palatable grass provides high live weight gain (LWG) and less chance of disease

Overwintering

Winter housing at 9 months old
Fed good quality silage with a Dry Matter Digestibility (DMD) of 75%
Poor quality silage should be supplemented with concentrates or catch crops

Year 2 - Turning into a Replacement Heifer

Heifers may be selected to replace older cows in the herd
Older cows are culled due to:
- Age
- Low milk production
- Health issues
Grading up the herd improves the genetic merit of the herd

Selecting Replacement Heifers

Heifers should:
- Have a good body condition score (BCS)
- Be of the correct breed
- Have a good milk production potential
- Be healthy and free of disease
- Have a good temperament

Body Condition Score (BCS)

Assesses the level of fat reserves in cattle, sheep, and pigs
Ranges from 1 to 5
BCS of heifers should be 3.25 at mating and reach a target weight of 300/330kg

Bull Selection for Replacement Heifer

Economic Breeding Index (EBI) is used to select bulls for breeding

Target Weight for Heifers

Should have a live weight gain (LWG) of 0.6-0.7kg per day
Fed grass, silage with 75% DMD ad-lib

Farm Safety

Important to ensure a safe working environment for farmers and animals

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Description

Learn about the life cycle of a replacement heifer from birth to 2 years, including gestation length, calf rearing, and preparation for milk production.