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Regulation of Feed Intake

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

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  1. Regulation of Feed Intake ANS/NUTRS 520 February 23,2012

  2. 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.

  3. Regulation of Feed Intake by Ruminants Physical - - - Fill - - - Energy Intake Dry matter - - - Metabolic - - - Nutritive value of feed, NEm

  4. 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)

  5. Physical Factors

  6. Forbes and Provenza, 2000

  7. 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)

  8. 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

  9. 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

  10. Palatability • Taste/flavor • Acidity • Sweet • Aroma/smell • Water content • Previous experience • Feed aversions

  11. Starch affects feed choice in lambs Villalba & Provenza (1997)

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

  13. Additive Effects

  14. Effects of Lactation

  15. Effects of Lactation Milk Production Feed Intake 0 8 16 24 32 40 Week of lactation

  16. 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

  17. 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

  18. Ionophores Stock et al., JAS 1995

  19. 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

  20. 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

  21. 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)

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