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Nutrient digestion and utilization in farm animals: modelling approaches.

Book cover for Nutrient digestion and utilization in farm animals: modelling approaches.

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This book contains 34 chapters on nutrition physiology and presents scientific research in modelling nutrient digestion and utilization in domestic animals, including cattle, sheep, pigs, poultry and fishes. It is divided into 6 parts that cover fermentation, absorption and passage; growth and development; mineral metabolism; methodology and model development; environmental impacts and animal prod...

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Chapter 19 (Page no: 192)

Development of a dynamic model of calcium and phosphorus flows in layers.

Phosphorus (P) is involved in most metabolic activities of the body as well as in bone formation. P and calcium (Ca) are closely related so that a deficiency in one can interfere with proper utilization of the other. In layers, requirement for dietary P is mainly due to the need to store Ca in bones prior to eggshell formation. Ca requirement for eggshell formation is high. If at any time during the day Ca requirement exceeds the amount of Ca absorbed from the gut, layers mobilize Ca, and consequently P, from medullary bones. P is then excreted in urine, potentially causing environmental pollution. A model of Ca and P dynamics in the layer was developed to describe and evaluate flows of Ca and P during the day. The model comprises eight state variables representing Ca and P in the crop, stomachs (proventriculus and gizzard), plasma and bone. P is defined as P absorbable at the terminal ileum. Zero pools are assigned to Ca and P in the duodenum. Outflow of Ca and P from crop and stomachs is assumed to obey mass-action kinetics. A higher fractional Ca absorption rate from the duodenum is assumed during eggshell formation than at times when there is no such formation. Eggshell formation commences 20 h before oviposition and follows a sigmoidal pattern. Ca and P in plasma can be used for egg synthesis, accretion in bone and excretion in urine. Michaelis-Menten forms represent utilization and production of Ca and P for bone accretion and resorption. Rate of utilization of plasma Ca and P for accretion depends on the more limiting of the two minerals. Rate of bone resorption is inhibited by plasma Ca or P level when Ca or P requirement exceeds supply from the gut, and consequently is related to the lowest level of the two minerals. Ca and P excreted in urine is the sum of basal maintenance requirement for Ca and P and amount of Ca or P in plasma that cannot be utilized for bone accretion because the other mineral is lacking. In the simulations, a light period of 16 h/day is assumed, and feed intake occurs continuously and only during the light period. Time of laying varies between 1 and 7 h after light is switched on. Simulated Ca and P absorption from the gut rises to a plateau until light is switched off, upon which absorption declines rapidly. However, depending on time of oviposition, simulated Ca requirement for eggshell formation is highest between 14 and 21 h after light is switched on. Because of the simulated imbalance between Ca absorption from the gut and Ca requirement for eggshell synthesis, Ca and consequently P are mobilized from bone. The model may be used to evaluate feeding strategies aimed at reducing P excretion to the environment in poultry manure.

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Chapter: 1 (Page no: 1) The Nordic dairy cow model, Karoline - development of volatile fatty acid sub-model. Author(s): Sveinbjörnsson, J. Huhtanen, P. Udén, P.
Chapter: 2 (Page no: 15) A three-compartment model of transmembrane fluxes of valine across the tissues of the hindquarters of growing lambs infected with Trichostrongylus colubriformis. Author(s): Roy, N. C. Bermingham, E. N. McNabb, W. C.
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Chapter: 4 (Page no: 33) Simulation of rumen particle dynamics using a non-steady state model of rumen digestion and nutrient availability in dairy cows fed sugarcane. Author(s): Collao-Saenz, E. A. Bannink, A. Kebreab, E. France, J. Dijkstra, J.
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Chapter: 10 (Page no: 99) Prediction of energy requirement for growing sheep with the Cornell Net Carbohydrate and Protein System. Author(s): Cannas, A. Tedeschi, L. O. Atzori, A. S. Fox, D. G.
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Chapter: 12 (Page no: 121) Relationships between body composition and ultrasonic measurements in lactating dairy cows. Author(s): Agnew, R. E. Yan, T. Patterson, D. C. Mayne, C. S.
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Chapter: 14 (Page no: 135) Simulating chemical and tissue composition of growing beef cattle: from the model to the tool. Author(s): Hoch, T. Pradel, P. Champciaux, P. Agabriel, J.
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Chapter: 20 (Page no: 211) Estimating the risk of hypomagnesaemic tetany in dairy herds. Author(s): Bell, S. T. McKinnon, A. E. Sykes, A. R.
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Chapter: 22 (Page no: 242) Empirical modelling through meta-analysis vs mechanistic modelling. Author(s): Sauvant, D. Martin, O.
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Chapter: 24 (Page no: 257) Segmented, constrained, non-linear, multi-objective, dynamic optimization methodology applied to the dairy cow ration formulation problem. Author(s): Boston, R. C. Hanigan, M. D.
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Chapter: 26 (Page no: 281) Advantages of a dynamical approach to rumen function to help to resolve environmental issues. Author(s): Bannink, A. Dijkstra, J. Kebreab, E. France, J.
Chapter: 27 (Page no: 299) Evaluation of models to predict methane emissions from enteric fermentation in North American dairy cattle. Author(s): Kebreab, E. France, J. McBride, B. W. Odongo, N. Bannink, A. Mills, J. A. N. Dijkstra, J.
Chapter: 28 (Page no: 314) Investigating daily changes in food intake by ruminants. Author(s): Dryden, G. M.
Chapter: 29 (Page no: 328) An ingredient-based input scheme for Molly. Author(s): Hanigan, M. D. Bateman, H. G. Fadel, J. G. McNamara, J. P. Smith, N. E.
Chapter: 30 (Page no: 349) Metabolic control: improvement of a dynamic model of lactational metabolism in early lactation. Author(s): McNamara, J. P.
Chapter: 31 (Page no: 366) Rostock feed evaluation system - an example of the transformation of energy and nutrient utilization models to practical application. Author(s): Chudy, A.
Chapter: 32 (Page no: 383) The Nordic dairy cow model, Karoline - description. Author(s): Danfær, A. Huhtanen, P. Udén, P. Sveinbjörnsson, J. Volden, H.
Chapter: 33 (Page no: 407) The Nordic dairy cow model, Karoline - evaluation. Author(s): Danfær, A. Huhtanen, P. Udén, P. Sveinbjörnsson, J. Volden, H.
Chapter: 34 (Page no: 416) A composite model of growth, pregnancy and lactation. Author(s): Vetharaniam, I. Davis, S. R.

Chapter details

  • Author Affiliation
  • Animal Nutrition Group, Wageningen University, PO Box 338, 6700 AH Wageningen, Netherlands.
  • Year of Publication
  • 2006
  • ISBN
  • 9781845930059
  • Record Number
  • 20063093904