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Regulation of Feed Intake. ANS/NUTRS 520 February 23,2012. References. Faverdin, P. 1999. The effect of nutrients on feed intake in ruminants. Proceeding of the Nutrition Society. 58:523 Fisher, D.W. 2002. A review of a few key factors regulating voluntary

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regulation of feed intake

Regulation of Feed Intake

ANS/NUTRS 520

February 23,2012

references
References
  • Faverdin, P. 1999. The effect of nutrients on feed intake in ruminants.
  • Proceeding of the Nutrition Society. 58:523
  • Fisher, D.W. 2002. A review of a few key factors regulating voluntary
  • feed intake in ruminants. Crop Science 42: 1651
  • Allen, M.S., B.J. Bradford and K.J. Harvatine. 2005. The cow as a model
  • to study food intake regulation. Annual Review of Nutrition. 25:523
  • Five Authors. 1996. Symposium on “Regulation of voluntary forage intake
  • in ruminants. J. Anim. Sci. 74:3029-3081.
  • NRC. 1987. Predicting feed intake for food-producing animals. Washington
  • D.C. National Academy Press
  • NRC Nutrient Requirements of Beef and Dairy Cattle publications.
regulation of feed intake by ruminants
Regulation of Feed Intake by Ruminants

Physical

- - - Fill - - -

Energy

Intake

Dry matter

- - - Metabolic - - -

Nutritive value of feed, NEm

regulation of intake
Regulation of intake
  • Capacity and fill of the digestive tract
  • Involved when forage-based diets are fed
    • Rate of digestion
    • Rate of passage
  • Consume feed to satisfy demands for energy
  • Involved when grain-based diets are fed
    • Nutrient effects
    • Metabolic effects (Seoane et al., 1972)
physical factors1
Physical Factors
  • Reticulum-Rumen
    • Tension receptors located in reticulum and cranial sac of rumen
      • Increases frequency of discharge of neurons in the ventral
      • medial hypothalamus and inhibits those in the lateral hypothalamus
  • Fill of the reticulum-rumen determined by rate of digestion and rate
  • of passage
  • Abomasum
    • Probably not involved in adults (abomasum does not
    • accumulate digesta in adults)
factors affecting fill of reticulum rumen
Factors Affecting Fill of Reticulum-Rumen
  • Rate of digestion and rate of passage
  • - Grinding - reduce particle size
  • - Chemical - increase rate of digestion
    • Treat roughage to make cellulose more available
factors affecting fill of reticulum rumen1
Factors Affecting Fill of Reticulum-Rumen
  • -
    • More susceptible to microbial attack - Increase rate of digestion
    • More susceptible to exit from rumen - Reduced omasal filtration
    • Increased uptake of water by feed particles
    • Change in ruminal location (stratification)
      • Lower digestibility in rumen
      • Increased intake
palatability
Palatability
  • Taste/flavor
    • Acidity
    • Sweet
  • Aroma/smell
  • Water content
  • Previous experience
    • Feed aversions
starch affects feed choice in lambs
Starch affects feed choice in lambs

Villalba & Provenza (1997)

effects of lactation
Effects of Lactation

Milk Production

Feed Intake

0 8 16 24 32 40

Week of lactation

environmental effects on feed intake
Environmental Effects on Feed Intake

Dry, minimum

mud

120

100

80

Cool night

Normal intake, %

Rain

Storm

Deep mud

Hot night

-10 0 10 20 30 40

Temperature, C

Predicting feed intake of food-producing animals, NRC, 1987

adjustments for environmental conditions
Adjustments for Environmental Conditions

Temperature, or Lot condition Adjustment, %

> 35 C no night cool -35

> 35 C with night cool -10

25 to 35 -10

15 to 25 None

5 to 15 3

-5 to 5 5

-15 to -5 7

< -15 16

Some mud, 10 to 20 cm -15

Severe mud, 30 to 60 cm -30

Predicting feed intake of food-producing animals, NRC, 1987

ionophores
Ionophores

Stock et al., JAS 1995

predicting feed intake of beef cattle 1996 beef nrc
Predicting Feed Intake of Beef Cattle1996 Beef NRC
  • Feedlot
  • NEm (Mcal/d) = SBW.75 (.2435 NEm - .0466 NEm2 - .1128)
      • SBW = Shrunk body wt in kg
      • NEm (Mcal/d)/NEm of diet = kg feed DM
  • All Forage Diet
  • DMI (kg/kg BW.75) = 0.002774 %CP - .000864 %ADF + .09826
  • Initial body weight of feeder cattle
  • DMI (kg/d) = 4.54 + .0125 IBW
      • IBW = initial body wt in kg
  • Breeding cattle
  • NEm (Mcal/d) = BW.75 (.04997 NEm2 + .04631)
      • Equation not accurate for feeds with NEm less than 1
predicting feed intake of dairy cattle 2001 dairy nrc
Predicting Feed Intake of Dairy Cattle2001 Dairy NRC
  • Lactating Holstein cows
  • DMI (kg/d) = (0.372 X FCM + 0.0968 X BW0.75)
  • X (1- e(-0.192X(WOL + 3.67)))
    • BW = body wt in kg
    • FCM = 4% fat corrected milk in kg/d
    • WOL = week of lactation
    • e = base of natural log
  • Growing heifers
  • DMI (kg/d) = (BW0.75 X (0.2435 X NEm - 0.0466 X NEm2 - 0.1128))/NEm
predicting feed intake of sheep
Predicting Feed Intake of Sheep

Legumes

DMI (g/d) = BWt.75 (-70.4 + 182 NEm - 53.2 NEm2)

Grasses and silages

DMI (g/d) = BWt.75 (-81.3 + 166 NEm - NEm2)

Pelleted diets

DMI (g/d) = BWt.75 (131 - 18.7 NEm)