in those hours. Overall, excretion of unutilized P is reduced from 221.1 to 154.3 mg/day. Further reductions are possible since bone P balance is positive and dietary P content may be reduced. The model developed is a tool to quan- tify Ca and P dynamics within a 24 h period based on an understanding of the processes involved and to evaluate Ca and P dynamics for a wide range of ovi- position times. Thus, the model will help to evaluate feeding strategies aimed at reducing P excretion to the environment in poultry manure.
Edwards, H., Jr (2000) Nutrition and skeletal problems in poultry. Poultry Science 79, 1018–1023.
Edwards, H., Jr and Veltmann, J., Jr (1983) The role of calcium and phosphorus in the etiology of tibial dyschondroplasia in young chicks. Journal of Nutrition 113, 1568–1575.
Etches, R.J. (1987) Calcium logistics in the laying hen.Journal of Nutrition 117, 619–628.
Fleming, R.H. (2008) Nutritional factors affect- ing poultry bone health. Proceedings of the Nutrition Society 67, 177–183.
Frost, T.J. and Roland, D.A., Sr (1991) The in- fl uence of various calcium and phosphorus levels on tibia strength and eggshell quality of pullets during peak production. Poultry Science 70, 963–969.
Frost, T.J., Roland, D.A. and Untawale, G.G. (1990) Infl uence of vitamin D3, 1α- hydroxyvitamin D3, and 1,25-dihydroxy- vitamin D3 on eggshell quality, tibia strength and various production parameters in com- mercial laying hens. Poultry Science 69, 2008–2016.
Gordon, R.W. and Roland, D.A., Sr (1997) Per- formance of commercial laying hens fed various phosphorus levels, with and with- out supplemental phytase. Poultry Science 76, 1172–1177.
Hudson, H.A., Britton, W.M., Rowland, G.N.
and Buhr, R.J. (1993) Histomorphomet- ric bone properties of sexually immature and mature white leghorn hens with evaluation of fl uorochrome injection on egg production traits. Poultry Science 72, 1537–1547.
Hurwitz, S. (1973) Regulation of calcium absorp- tion by fowl intestine. American Journal of Physiology 225, 150–154.
Hurwitz, S. and Bar, A. (1965) Absorption of cal- cium and phosphorus along the gastrointes- tinal tract of the laying fowl as infl uenced by dietary calcium and egg shell formation.
Journal of Nutrition 86, 433–438.
Hurwitz, S. and Bar, A. (1969) Intestinal calcium absorption in the laying fowl and its impor- tance in calcium homeostasis. American Journal of Clinical Nutrition 22, 391–395.
Johnston, M. and Ivey, E. (2006) Parathyroid and ultimobranchial glands: calcium metabolism
in birds. Seminars in Avian and Exotic Pet Medicine 11, 84–93.
Jones, G., Strugnell, S. and DeLuca, H. (1998) Current understanding of the molecular ac- tions of vitamin D. Physiological Reviews 78, 1193–1231.
Kebreab, E., France, J., Kwakkel, R.P., Leeson, S., Darmani Kuhi, H. and Dijkstra, J.
(2009) Development and evaluation of a dynamic model of calcium and phospho- rus fl ows in layers. Poultry Science 88, 680–689.
Keshavarz, K. (1998) Investigation on the possibility of reducing protein, phospho- rus, and calcium requirements of laying hens by manipulation of time of access to these nutrients. Poultry Science 77, 1320–1332.
Keshavarz, K. and Austic, R.E. (1990) Effects of dietary minerals on acid–base balance and eggshell quality in chickens. Journal of Nutrition 120, 1360–1369.
Kramer, M.R. and Scholten, H. (2001) The Smart approach to modelling and simula- tion. In: Heemink, A.W., Dekker, L., Arons, H.d.S., Smit, I. and van Stijn, T.L. (eds) Proceedings of Eurosim 2001, Shaping Fu- ture with Simulation, 4th International EU- ROSIM Congress, in which is incorporated the 2nd Conference on Modelling and Simulation in Biology, Medicine and Bio- medical Engineering. Technical University Delft, Delft, the Netherlands, 6 pages on CD-ROM, ISBN: 90-806441-1-0.
Maynard, L., Loosli, J., Hintz, H., Warner, R.
and Zappa, C.R. (1979) Animal Nutrition, 7th edn. McGraw-Hill, New York.
Mongin, P. and Saveur, S. (1974) Voluntary food and calcium intake by the laying hen.
British Poultry Science 15, 349–359.
Mueller, W.J., Schraer, R. and Scharer, H.
(1964) Calcium metabolism and skeletal dynamics of laying pullets. Journal of Nu- trition 84, 20–26.
Nahm, K.H. (2008) Effi cient phosphorus utiliza- tion in poultry feeding to lessen the environ- mental impact of excreta. World’s Poultry Science Journal 63, 625–654.
National Research Council (1994) Nutrient Re- quirements for Poultry. National Academy Press, Washington, DC.
Newman, S. and Leeson, S. (1997) Skeletal in- tegrity in layers at the completion of egg production.World’s Poultry Science Jour- nal 53, 265–277.
Rama Rao, S.V., Panda, A.K., Raju, M., Shyam Sunder, G. and Praharaj, N.K. (2003) Requirement of calcium for commercial broilers and white leghorn layers at low dietary phosphorus levels. Animal Feed Science and Technology 106, 199–208.
Rama Rao, S.V., Raju, M.V.L.N., Reddy, M.R.
and Pavani, P. (2006) Interaction between dietary calcium and non-phytate phospho- rus levels on growth, bone mineralization and mineral excretion in commercial broilers.
Animal Feed Science and Technology 131, 135–150.
Rao, K.S. and Roland, D.A., Sr (1990) Infl u- ence of dietary calcium and phos phorus on urinary calcium in commercial leghorn hens.Poultry Science 69, 1991–1997.
Saunders-Blades, J.L., MacIsaac, J.L., Korver, D.R. and Anderson, D.M. (2009) The ef- fect of calcium source and particle size on the production performance and bone quality of laying hens. Poultry Science 88, 338–353.
Scanes, C.G., Campbell, R. and Griminger, P.
(1987) Control of energy balance during egg production in the laying hen. Journal of Nutrition 117, 605–611.
Shafey, T.M. (1993) Calcium tolerance of growing chickens: effect of ratio of dietary calcium to available phosphorus. World’s Poultry Science Journal 49, 5–18.
Sharpley, A. (1999) Agricultural phosphorus, water quality, and poultry production: are they compatible? Poultry Science 78, 660–673.
Simons, P.C.M. (1986) Major minerals in the nutrition of poultry. In: Fisher, C. and Boor- man, K.N. (eds) Nutrient Requirements of Poultry and Nutritional Research. Butter- worths, London, pp. 141–154.
Soares J.H., Jr (1984) Calcium metabolism and its control – a review. Poultry Science 63, 2075–2083.
Sykes, A.H. (1984) Food Intake and Its Control.
Academic Press, London.
Tanaka, Y. and DeLuca, H. (1973) The con- trol of 25-hydroxyvitamin D metabolism by inorganic phosphorus. Archives of Biochemistry and Biophysics 154, 566–
574.
Thornley, J.H.M. and France, J. (2007) Mathe- matical Models in Agriculture, 2nd edn.
CAB International, Wallingford, UK.
Tolboom, J.G. and Kwakkel, R.P. (1998) Dy- namic modelling of Ca and P fl ows in lay- ers: prospects to reduce dietary digestible P levels.British Poultry Science, 39 (Suppl.), S43–S44.
Underwood, E.J. (1981) The Mineral Nutrition of Livestock. CAB International, Walling- ford, UK.
Van der Klis, J.D. and Versteegh, H.A.J. (1995) De afbraak van fytaat-fosfor in het maagdarmkanaal van vleeskuikens in afhankelijkheid van grondstof, opneem- baar forfor en calciumgehalte. DLO, Institute for Animal Sciences and Health, Lelystad.
Van der Klis, J.D. and Versteegh, H.A.J. (1996) Het gebruik van het opneembaar fosforsy- steem bij leghennen. DLO, Institute for Animal Sciences and Health, Lelystad.
Van Krieken, M.A. (1996) Calcium and phos- phorus in layers [in Dutch]. MSc thesis, Wageningen University, the Netherlands.
Waldroup, P.W. (1999) Nutritional approaches to reducing phosphorus excretion by poul- try. Poultry Science 78, 683–691.
Whitehead, C.C. (2004) Overview of bone biol- ogy in the egg-laying hen. Poultry Science 83, 193–199.
Whitehead, C.C. and Fleming, R.H. (2000) Osteoporosis in cage layers. Poultry Sci- ence 79, 1033–1041.
© CAB International 2010. Phosphorus and Calcium Utilization and
Requirements in Farm Animals (D.M.S.S. Vitti and E. Kebreab) 151
10 Effi ciency of Phosphorus
and Calcium Utilization in Dairy Cattle and Implications
for the Environment
A. B
ANNINK,
1L. Š
EBEK1 ANDJ. D
IJKSTRA21Wageningen University Research Centre, Lelystad, the Netherlands;
2Wageningen University, Wageningen, the Netherlands
Introduction
Phosphorus (P) is an essential element involved in numerous metabolic pro- cesses in the body of cattle. Effi ciency of P utilization (the ratio of P excreted in milk to dietary P intake) is highly variable but in dairy cattle it is usually about 0.30 (Wu et al., 2000). The excess of P may be detrimental to the environment.
Of particular concern is the amount of P surplus per hectare and the limited potential of soils to further accumulate P. Some soils are saturated with P as a result of intensive fertilization for many decades. Hence, a considerable fraction of manure P may leach from soils and contributes to water eutrophication. Leg- islation on P management is, or may become, a more important constraint on farming practice than legislation on N management (e.g. EU Water Framework Directive, http://eur-lex.europa.eu). For this reason, it is expected that the effi - ciency of utilization of P resources in intensive dairy farming has to increase substantially in the near future.
Besides environmental constraints, there are also economic or political argu- ments for improving P effi ciency on dairy farms. World P resources for artifi cial fertilizer are becoming scarce and may become more expensive at a rapid rate (Cordell et al., 2009). There is no atmospheric loss of manure P such as for manure nitrogen (N). However, atmospheric N can be bound again by root sys- tems of certain plant species and enrich soil N. Also, atmospheric N is used to produce artifi cial N fertilizer. Such recycling is not possible for P, which to a large extent is permanently lost from watersheds and rivers eventually to oceans. For this reason, P is lost much more permanently than N.
Scarcity of P stocks and more stringent future legislation to preserve water quality may lead to an increased pressure to maximize P utilization by cows and minimize P losses from manure. This can be achieved by lowering farm P import
from purchased feeds and artifi cial fertilizers, and by making more effi cient use of feed and manure P. A more effi cient use of feed P can be achieved by reducing the amount of P ingested by dairy cows per unit milk yield. This chapter dis- cusses the implications of nutrition on the effi ciency of P utilization by cows, and puts this in the perspective of P balance at a farm level. To a lesser extent, effi - ciency of calcium (Ca) utilization is also discussed because the vast majority of P and Ca are stored in bones in an almost constant ratio of 1:2. We have addressed Ca as required for proper P utilization but not from a perspective of milk fever in early lactation.