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27 Cards in this Set
- Front
- Back
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Yearly life cycle |
Birth (45kg) - Pre-weaning period Weaning at 2 months - Pre-breeding period Breeding at 15 months - Bred period Calving at 24 months *At 6 months of age, called an 'Open Heifer' *After breeding at 15 months, called a 'Bred heifer' |
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Failure of Transfer of Passive Immunity |
Pre-weaning - increased mortality - increased disease occurrence and severity - decreased growth Post-weaning - increased morbidity - reduced milk prod'n 1st and 2nd lactations Measurement: - Serum IgG: 10mg/mL (in lab) - Serum total protein: 5.2 g/dL (on farm) |
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Passive immunity depends on: |
Quality of colostrum (minimum of 50mg/ml of IgG, use RID to measure) Quantity of colostrum consumed Timing of colostrum feeding |
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Measuring colostrum quality on farm |
Colostrometer: use 80 mg/ml as minimum for good quality colostrum - measures specific gravity - antibodies are a big part of protein in colostrum - protein accounts for high percentage of total solids - total solids correlated to specific gravity Brix refractometer: - measures amount of light refracted as it passes through liquid Degrees Brix: measure of sugar content of aqueous olution %Brix of ≥ 23: use colostrum for 1st feeding %Brix of 18-22: use colostrum for 2nd and 3rd feedings %Brix ≤17: use for calves >24 hrs of age |
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Problems with colostrometer |
Temperature sensitive - over-estimates at low temp - under-estimates at high temp * Should be read at room temp Glass float is fragile and breaks easily Overestimates colostrum quality |
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Brix refractometer advantages |
- fast - not temp dependent - requires only few drops of colostrum |
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Brix refractometer disadvantages |
- not as highly correlate to lab-measured IgG compared to colostromer (but still better than nothing) |
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Factors affecting colostrum quality |
Immune status of cow Vaccination status - make sure cows vaccinated properly at appropriate time to pass on IgG First milking volume? Pre-milking/leaking - usually consists of high quality colostrum First milking time - longer delay between calving and first milking, more diluted IgG levels get Breed - Jerseys highest quality, Holsteins lowest Colostrum handling and storage - milk into clean bucket and put in fridge right away to avoid bacterial contamination (have negative effect on IgG absorption itself, and also bacteria can be absorbed into intestinal wall <24 hrs of age |
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Colostrum quantity |
Want 200g IgG within 6 hours of birth - volume depends on IgG content of colostrum Rule of thumb: - feed 10% BW in first feeding (usually 3-4L) - feed another 2L within 12 hours - feed at 20% of birth weight for 2-3 days |
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Colostrum Timing (absorption) |
Want to maximize absorption Want to minimize bacterial colonization - First 24 hrs following birth, antibodies can be directly absorbed into bloodstream - After 24 hrs, gut closes - inability to absorb antibodies |
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Colostrum vs whole milk Composition |
Total solids highest in 1st milking, drops to almost half in whole milk Fat highest in 1st milking Protein highest in 1st milking Lactose lowest in 1st milking Vitamin A and minerals highest in first milking |
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Pasteurization of Colostrum |
60C for 60 minutes |
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Milk replacer composition: |
1st replacer: - 24-28% protein, all derived from milk protein - 20-22% fat Subsequent replacer - 20-26% protein, half derived from milk protein (half veggie sources) - 10-12% fat |
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Recommended feeding of whole milk |
Minimum total daily intake of 20% of body weight until 28 days of age |
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What is waste milk? |
Milk that cannot be sold usually due to mastitis or antibiotic treatment - not ideal to feed to calves due to high bacterial count - pasteurization recommended to reduce microbial load |
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Pasteurization of waste milk |
Benefits: - higher BW gains - reduced morbidity and mortality - decreased veterinary costs Types: Batch: milk heated to 63C(145F) for 30 minutes Continuous flow, HTST: 15 sec at 72C (161F) |
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Factors for rumen development |
**Crucial for early weaning and good calf growth Establishment of bacteria in the rumen Liquid in rumen - must offer calves water Outflow of material from rumen - with intake of dry feed, rumen contractions begin Absorptive ability - ruminal papillae development stimulated by butyrate and propionate (end products of starch metabolism by bacteria) Substrate available in rumen - fermentation of grains leads to production of propionate and butyrate, therefore papillae development - fermentation of hay leads to prouction of acetate with minimal effect on papillae development **Therefore grain feeding is essential for proper rumen development! |
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Establishment of rumen bacteria |
Rumen sterile at birth By 24 hrs, aerobic bacteria present With dry feed intake, bacterial population changes - methanogens - proteolytic bacteria - cellulolytic bacteria |
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What is calf starter? |
Dry grain mix offered early in life Very palatable - textured - contains molasses - not mouldy 19-20% crude protein on DM basis Usually contains coccidostat such Deccox Feed small amounts, fresh, daily |
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Weaning overview |
Calves must have adequate rumen development! With abrupt weaning, use calf starter intake as criterion: - when calves consume 1 kg calf starter for at least 3 consecutive days, they can be weaned With higher milk amounts fed now gradual weaning recommended - calf starter should be one kg/day before milk is totally withdrawn - wean over 7-10 days, less milk given each day Rule of thumb: heifers should double their birth weight by 8 weeks of age |
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Weaning management |
Move and wean calves on different days Ensure calves drinking adequate amounts of water Keep feed type constant (same calf-starter) Use small-group housing Provide good ventilation |
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Optimum weaning situation |
Wean 3-5 calves of similar ages Move calves 2-4 weeks after weaning to location of similar environment - adequate feed bunk space and easily accessible water Maintain same forages and grains as fed before weaning Do not make any other management changes Observe frequently for first few days after weaning |
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Heifer housing |
After weaning, heifers housed in groups Group sizes vary: - normally smaller groups (5-8) until breeding - then larger groups after breeding (10-15) |
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Feeding heifers between weaning and 6 months of age |
Feed high quality forages - pasture not recommended Feed max of 5-6 lbs of grain/head/day Grain mix composition depends on forage quality - if you feed mostly legume hay, need grain mix at 14% CP - if you feed mostly grass hay, need higher protein content - limit corn silage (too high energy, will make them fat) TMRs can be fed |
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Feeding heifers between 6 months of age and one month before calving |
Rumen is fully functional by 6 months of age - heifer can consume more forage Supplemental grain feeding may be required (if forage not good quality) Feed forages free-choice! - more acceptable to feed grass hay at this age, can supplement with more grain TMRs can be fed |
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ADG for heifers 6 months to 1 month before calving: |
1.7 to 2 lbs /day (similar to backgrounding in beef cows) |
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Dietary Protein requirements for heifers (DM basis) |
Birth - 2 months: 19-20% 3 - 8 months: 15-17% (200-500 lb BW) 9 - 13 months: 14-15% (500-800 lb BW) 14 - 22 months: 12-13% (>800lb) |
