ch 9

Dairy Replacement Heifers

Overview of Heifer Rearing

  • Raising heifers until they are 2 years old and ready to have their first calf.

Maternity Management

  • Maternity Pen:
    • Move heifers to a well-bedded maternity pen 5 days before the due date.
    • Importance of bedding for comfort and hygiene.

Newborn Calf Care

  • Newborn Procedures:
    • Dip all navels immediately after birth using 7% iodine to prevent infection (Joint ill or navel ill).

Importance of Colostrum

  • Colostrum:

    • Defined as the "first milk" rich in antibodies that protect calves from diseases.
    • Essential for nutrient supply post-birth until the calf's immune system functions independently.

  • Physical Characteristics and Composition of Colostrum vs. Whole Milk:

    • Table 7.2: Shows specific gravity, pH, total solids, fat, solids-not-fat, total protein, casein, albumin, immunoglobulins, non-protein nitrogen, lactose, and ash percentages in both colostrum and whole milk over postpartum milking stages.
    • Example measurements include:
    • Specific gravity for colostrum ranges from 1.056 (1st milking) to 1.032 (5th milking).
    • Total solids start at 23.9% and decrease to 12.9% by 5th milking.
    • Total protein also follows a decreasing trend from 14.0% to 3.1%.

Colostrum Quality Assessment

  • The 5 Qs of Colostrum:
    • Quickly: Administer within 2 hours after birth.
    • Quantity: 4 liters (1 gallon) fed to the calf.
    • Quality: Minimum 50 grams of IgG per liter of colostrum.
    • Squeaky Clean: No bacteria, as bacterial load can reduce IgG uptake.
    • Quantify: Check for at least 10 grams of IgG in blood.

Failure of Passive Transfer

  • Consequences:
    • Higher calf death losses correlate with IgG levels (e.g., lower than 10 mg/ml leads to a 4x increase in death rate).
    • Calf survival rates decrease sharply with failure to meet IgG thresholds.

Growth Monitoring and Management

  • Monitoring Heifer Growth:
    • Evaluate by measuring height and weight against standards to identify issues in the heifer program.
    • Heifer rearing is among the top costs of milk production; efficient management is crucial.
    • Aim for heifers to be ready for calving at 22-24 months.

Feeding Guidelines for Calves

  • Solid Feed Introduction:
    • 1 week old: 1 gallon of milk 2 times a day.
    • 2 weeks old: ½ lb of grain per day alongside forage.
    • Continue increasing grain intake to reach 4 lbs by 6 weeks, and 8 lbs by 80 days.
  • Weaning Recommendations:
    • Do not wean calves until they are consuming 8 lbs of grain per day.
    • Move to running pens after 80 days on the same feed.

Challenges and Monitoring

  • Surpassing Growth Rates:
    • Daily gain should ideally range from 1.6 to 1.9 lbs/day; deviations can impact future milk production.
  • Housing Conditions:
    • Poor housing and ventilation can lead to respiratory issues, impeding growth despite good feeding practices.

Calf Rearing Equipment

  • Key Tools:
    • Stomach tube bags for colostrum administration.
    • Brix Refractometer or hydrometer for quality testing.
    • Automatic calf feeders for more efficient feeding practices.

Vaccination Protocols

  • Initial Vaccination:
    • Day 2 Procedures: Intranasal vaccines (Inforce 3 and Nasalgen 3) to combat respiratory diseases.
    • Administer 1 ml in each nostril; revaccinate calves before 6 months old.

Colostrum Management Practices

  • Ideal Practice: Get colostrum into the calf quickly, sanitize equipment after each use to prevent contamination.
    • Consider colostrum replacers in emergencies.

Heifer Growth Charts and Data

  • Growth Monitoring Tasks:
    • Use growth charts for evaluating heifer management effectiveness.
    • Identify if groups of heifers are underweight or overweight, adjust feeding strategies accordingly.

Long-term Considerations

  • Culled cows tend to spend excessive lifetime as growing heifers, indicating the importance of efficient heifer development.