Dairy Heifers and Growth

Question 1

Bovine vs Human colostrum

Answer 1

Bovine is higher in proteins, lower in lactose and higher in fats. Also much higher in energy

Question 2

Ig’s passed in colostrum?

Answer 2

IgG1 most important and abundant, IgA and IgM account for about 5% each of passed Ig’s

Question 3

Nutritional components of colostrum

Answer 3

Immunoglobulins, Maternal leukocytes, cytokines and growth factors, nutrients (4x normal milk protein amounts)

Question 4

lack of proper passive transfer leads to:

Answer 4

1. increased morbidity and mortality rates
2. decreased daily weight gain
3. decreased milk production on first lactation
4. increased culling risk in first lactation

Question 5

Factors affecting adequate passive transfer

Answer 5

timing (closed after 24h), IgG concentration (at least 50g/L), Parity, breed, colostrum handling, pooling?

Question 6

Storage of colostrum

Answer 6

can be refrigerated or frozen within 1 hour of collection. Can keep for 1 year if no freeze/thaws. Defrost slowly to avoid protein denaturation

Question 7

Pasteurizing colostrum

Answer 7

Must be longer and at lower temperature to preserve proteins

Question 8

Colostrum Supplement vs Replacer

Answer 8

Supplement: 50g IgG, no nutrient pack, cheap
Replacer: 100g IgG per dose, nutrients added, more expensive
*feed separate to natural colostrum

Question 9

3 Phases of digestive physiology in cattle

Answer 9

1. Pre-ruminant: 2-3 weeks, relies almost entirely on milk
2. Transitional: until weaning, milk and starter grain, rapid expansion of rumen epithelium
3. Ruminant: at weaning, fermentation of dietary carbs to produce VFAs as major energy source

Question 10

Metabolizable energy requirement for maintenance at thermoneutral conditions

Answer 10

2.5L whole milk, 3L of milk replacer

Question 11

Thermoneutral zone for young vs old

Answer 11

young: 15-25 C
old: 5-25 C

Question 12

Cold weather feeding strategies

Answer 12

1. increased milk volume
2. introduce third feeding
3. switch to higher energy/higher fat milk replacer
4. supplement milk replacer with added fat or additional milk solids
5. add additional milk replacer solids to each feeding to increase concentration

Question 13

Conventional feeding approach

Answer 13

liquid feed: 8-10% of body weight+ starter from 1st week of life. stimulates early intake of starter (main pportion of energy is from grains)
200-300g/d growth at beginning, as starter increases so does growth rates

Question 14

Accelerated feeding approach

Answer 14

liquid feed: 12% body weight week 1 then 16% until 1 week pre-weaning. Milk feeding about 2x normal, intake of starter lags behind conventional system but increases at the same rate once liquid is cut back
Calves not weaned until eating 1 kg of starter daily
Benefits: better ability to withstand infection, reach breeding age quicker, possible increased milk production
most expensive, best result

Question 15

Liquid feed choices

Answer 15

Non-sellable milk: colostrum, transition milk, milk that is withheld due to drugs
Non-pasteurized waste milk: do not use! may have diseases!
Milk replacers: more expensive but: very consistent, easy, storage is flexible, disease control