Dairy Heifers & Growth Flashcards
(24 cards)
Describe colostrum.
-1st milk secreted at time of parturition
-diff from milk secreted later
-contains more lactalbumin & lactoprotein
>rich in ABs = passive immunity to newborn
Describe the nutritional components of colostrum.
- 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 - Maternal leukocytes
-1x10^6 cells/mL of maternal leukocytes, macrophages, T+B lymphocytes, neutrophils - Nutrients
-x4 inc in protein Vs milk
-certain vit & minerals are also inc in Vs milk
Describe the cytokines & GF of colostrum.
-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
Describe the imp of passive transfer in calves.
- Inc morbidity & mortality rate
- Dec avg daily weight gain
- Dec milk prod in 1st lactation
- Inc risk of culling in first lactation
Describe the types of placentation.
6 layers
#2
Describe the failure of transfer of passive immunity.
-calf serum IgG conc <10mg/ml * when sampled between 24-48 hrs old
Describe factors affecting adequate passive transfer.
- Timing
>after 24h no passive transfer - IgG conc
- Parity
>more calves = better colostrum - Breed
- Colostrum handling
- Pooling ?
Describe the components of a successful colostrum management program.
- 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 - 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) - Timing
-first feeding in 1-2h of birth within 6h (latest)
-gut closes at 24h - Method of feeding
-hand feeding w bottle VS esophageal feeder - 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
Describe storage & pasteurization.
-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
Describe colostrum replacers & supplements.
-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 *]
Describe the 3 phases of digestive physiology of the calf.
- Pre ruminant
-2-3wk, negligible dry feed, rely on milk or milk replacer, esophageal groove - Transitional
-until weaning, milk & starter gain, rapid expansion of vol & differentiation of rumen epi so VFA made & absorbed - Ruminant
-at weaning, fermentation of dietary carb to make VFA for most of energy & AA from proteins in the microbial mass
Describe the digestive physiology of the calf & milk.
-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
Describe the digestive physiology of the calf & VFAs.
-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
Describe nutrient requirements - energy & protein.
-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
Describe cold weather feeding strategies.
- Inc vol of milk
- Introduce a 3rd feeding
- Switch to higher energy (higher fat) milk replacer
- Supplement milk replacer w added fat or additional milk solids
- Add additional milk replacer solids to each feeding
Describe nutrient requirement - vit & minerals.
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
Describe the conventional feeding approach.
-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
Describe the accelerated feeding approach.
-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
Describe liquid feed choices.
-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
Describe milk replacer additives.
- Probiotics
- Prebiotics
- Antibiotics
- Coccidiostats
Describe ruminal development.
-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
Describe nutrition from weaning to breeding - ration.
-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
Describe nutrition from weaning to breeding - diet.
-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
Describe post weaning growth considerations.
-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 *
