Dairy Heifers & Growth

Question 1

Describe colostrum.

Answer 1

-1st milk secreted at time of parturition
-diff from milk secreted later
-contains more lactalbumin & lactoprotein
>rich in ABs = passive immunity to newborn

Question 2

Describe the nutritional components of colostrum.

Answer 2

1. Immunoglobulin
   -IgG, IgA, IgM
   -85%-90% & 5-7% respectively of total Lg in colostrum with IgGI accounting for 80-90% of total IgG
   -IgE present = early protection against intestinal parasites
2. Maternal leukocytes
   -1x10^6 cells/mL of maternal leukocytes, macrophages, T+B lymphocytes, neutrophils
3. Nutrients
   -x4 inc in protein Vs milk
   -certain vit & minerals are also inc in Vs milk

Question 3

Describe the cytokines & GF of colostrum.

Answer 3

-lactoferrin, lactoperoxidase, lysozyme, antimicrobial
-oligosaccharide competitive inhibitor for binding sites on epi surface of intestine
-IGF-I key regulator in development of GIT
-trypsin inhibitor = protect IgG & other proteins from proteolytic degradation in intestine
-TGF-b2 & growth hormone

Question 4

Describe the imp of passive transfer in calves.

Answer 4

1. Inc morbidity & mortality rate
2. Dec avg daily weight gain
3. Dec milk prod in 1st lactation
4. Inc risk of culling in first lactation

Question 5

Describe the types of placentation.

Answer 5

6 layers
#2

Question 6

Describe the failure of transfer of passive immunity.

Answer 6

-calf serum IgG conc <10mg/ml * when sampled between 24-48 hrs old

Question 7

Describe factors affecting adequate passive transfer.

Answer 7

1. Timing
   >after 24h no passive transfer
2. IgG conc
3. Parity
   >more calves = better colostrum
4. Breed
5. Colostrum handling
6. Pooling ?

Question 8

Describe the components of a successful colostrum management program.

Answer 8

1. Quality: >50g/L *
   -colostrometer, refractometer, cow side immunoassay test
   -milk cow ASAP to max IgG conc
   -short or no dry period will dec IgG
   -vaccinate dam 3-6wk pre calves
   -season/vol
2. Quantity
   -4L total for dairy
   -rec to feed 10-12% body weight in first feeding
   -aim for 100g IgG in first feeding (200 IgG total)
3. Timing
   -first feeding in 1-2h of birth within 6h (latest)
   -gut closes at 24h
4. Method of feeding
   -hand feeding w bottle VS esophageal feeder
5. Handling
   -fresh colostrum <100,000 Cfu/ml total bacteria & <10,000 cfu/ml coliforms
   -prep udders prior to milking, sanitize collection equipment - bucket, teats, bottle etc

Question 9

Describe storage & pasteurization.

Answer 9

-refrigerate/freeze within 1h of collection
-keep for 1y when frozen w/o multiple freeze/thaw cycles
-defrost slowly & avoid extreme temp 60c
-duration of refrigeration:
>IgG in raw refrigerated colostrum is stable for 1 week but bacteria counts may reach high conc (bad)
>preserved in K sorbets .5% raw milk last 6d
>pasteurized 8-10d
-normal milk pasteurization unacceptable for colostrum
>milk = 63c for 30 min or 72c for 15s
>colostrum = 60c for 60 min

Question 10

Describe colostrum replacers & supplements.

Answer 10

-agalactia, supply shortage, death of dam, disease control
-powdered commercial CS or CR products contain bovine Ig-lacteals or plasma derived
-CS: less than 50g of IgG per dose, no nutrient pack, only to supplement (not replace) * existing colostrum [$5-7/dose *]
-CR: min of 100g of IgG per dose, nutritional source of protein, energy, vit, minerals, to completely replace maternal colostrum [$20-30/dose *]

Question 11

Describe the 3 phases of digestive physiology of the calf.

Answer 11

1. Pre ruminant
   -2-3wk, negligible dry feed, rely on milk or milk replacer, esophageal groove
2. Transitional
   -until weaning, milk & starter gain, rapid expansion of vol & differentiation of rumen epi so VFA made & absorbed
3. Ruminant
   -at weaning, fermentation of dietary carb to make VFA for most of energy & AA from proteins in the microbial mass

Question 12

Describe the digestive physiology of the calf & milk.

Answer 12

-milk diet = caesin protein denatured in acidic abomasum (pH2) -> renin + Ca loss -> coagulation of casein protein where fat * is also entrapped in ‘coagulum’ *
>liquid portion: whey, protein, lactose, sol min & vit
—enter SI in 2-3h after meal, casein coagulum = slower
-lactose hydrolyzed -> sugar, glu, galactose, by lactase & monosaccharides absorbed into epi cells by active transport proteins
-pancreatic secretion of amylase + intestinal activity of maltase low at birth then inc over 1st weeks

Question 13

Describe the digestive physiology of the calf & VFAs.

Answer 13

-calf begin to consume starter conc -> microbial pop ferment carb to VFA (main energy source for ruminants)
-VFA: acetic acid (50-60%), butyric acid (18-20%), propanoic acid (12-18%) *
-butyric acid (lesser extent, proponic acid), stim differentiation of ruminal absorptive epi into papillae
-vol & musculature develop in resp to physical bulk in rumen
-papillae become functional & able to absorb VFA -> pH of rumen stabilizes and begin to inc
-until pH is stable at 6 the ability for cellulolytic bacteria to thrive is limited

Question 14

Describe nutrient requirements - energy & protein.

Answer 14

-calves <100kg: metabolizable energy (ME) = total feed intake - loss of energy in feces, digestive gasses, urine
-ME requirements for maintenance * under thermoneutral conditions 1.75Mcal/d for 45kg calf = 2.5L of whole milk or 3L milk replacer (lower fat content) *
>thermoneutral: calves <21d is 15-25c & older the lower critical temp is 5c
—bedding: straw best when cold, sand best when hot
-protein req for maintenance + growth as source of AA
-energy = protein req for maintenance small & not altered by temp stress
*EX: 45kg calf req 72.5 g/d of milk replacer powder to meet maintenance req & maintain body temp compared w 382g/d powder under thermoneutral conditions

Question 15

Describe cold weather feeding strategies.

Answer 15

1. Inc vol of milk
2. Introduce a 3rd feeding
3. Switch to higher energy (higher fat) milk replacer
4. Supplement milk replacer w added fat or additional milk solids
5. Add additional milk replacer solids to each feeding

Question 16

Describe nutrient requirement - vit & minerals.

Answer 16

VIT B1 MOST IMP
-req for vit & mineral in young dairy calves less well defined than other FA + adults
-whole milk adequate in all nutrients except iron, mG, Se
-milk replacer supplemented w minerals & vit to meet estimated req so deficiencies or imbalances are rare
-starters are supplemented w most minerals & fat sol vit (A,D,E,K)
-ruminal syn -> no req established for supplemental vit B in starter
-calf doesnt have dietary req for vit C
-water nutrition often the weakest link on dairy farms
>development of starter intake depend no water intake

Question 17

Describe the conventional feeding approach.

Answer 17

-limited liquid feed: 8-10% body weight + starter offered from 1st week of life
-restricted liquid feeding approach to stim early intake of starter & to min input costs of higher Val feed
-calf starter main portion of energy derived from cereal grains (corn, barley)
-restricted feeding allows only for maintenance needs 200-300g/d of growth under thermoneutral conditions
-starter intake inc (2x every wk) enough nutrients consumed to allow calve to grow

Question 18

Describe the accelerated feeding approach.

Answer 18

-liquid feeding: 12% bwt week 1 then 16% bwt 1 wk prior to weaning
-milk feeding rate about 2x conventional
-intake of starter lags behind calves on conventional system but inc at same rate once amt of liquid is cut back
-calves shouldn’t be weaned until consistently eating 1kg of starter daily *
-benefits of improved nutritional status in first 2-3wk:
>better ability to withstand inf challenge
>reach breeding age sooner
>inc milk prod
-intermediate program *: less slump in growth around weaning + fewer digestive upsets in calves than more aggressive liquid feeding programs while providing improved nutritional status during first 2-3wk

Question 19

Describe liquid feed choices.

Answer 19

-non sale able milk: colostrum, transition milk, milk w drug residue
-non pasteurized waste milk for calves discouraged bc dz transmission
-milk replacers: more expensive than surplus colostrum, transition milk, pasteurized waste milk, milk replacer have adv:
>consistency of product from day to day
>easy & flexibility of storage
>disease control

Question 20

Describe milk replacer additives.

Answer 20

1. Probiotics
2. Prebiotics
3. Antibiotics
4. Coccidiostats

Question 21

Describe ruminal development.

Answer 21

-calves consume dry feed -> rumen develops microbial pop + absorptive fxn
-ferm of dry feed to VFA to drive growth & differentiation of epi
-feeding forage in early stage controversial
>low in sugar & high in poor fermented fiber
>pop of cellulolytic bacteria become est in few days after birth = cant inc # needed for sig forage ferm until rumen pH stable or at 6
>physical size of rumen limited in young calf = accumulation of undigested forage material in rumen dec voluntary intake of starter
-some fiber needed to maintain abrasion factor to prevent abnormal development of rumen papillae
-complete starter fed contain long particles = supplemental forage not needed esp if bedded on straw

Question 22

Describe nutrition from weaning to breeding - ration.

Answer 22

-true ruminant 42-45d *
-calves maintained on starter ration until transition pens @10-14wk
>transition to grower ration of simple comp & lower protein content + forage introduced
-2.5-5kg of grower ration from 100kg breeding

Question 23

Describe nutrition from weaning to breeding - diet.

Answer 23

-diet has metabolizable protein to lower GIT to support lean tissue growth w/o fat
-TMR: balance formulated mix of forage & grain - vary w production stage
-move heifer to TMR in early grower phase by mixing starter grain w sm amt of high group lactation TMR in DM ratios 9:1 to 4:1
>after sev wks -> heifer move to TMR containing silage

Question 24

Describe post weaning growth considerations.

Answer 24

-diet formulated to allow heifer to reach breeding age ASAP w/o fat
>need sufficient metabolizable protein
-target BW @ first breeding = 55% mature BW w heifer calving first time @ 82% BW
-Holstein heifer calving @22.5 mo @ target post partum BW of 526kg the target BW gain pre breeding is .87kg/d *