Application of nutrient requirement systems to grazing cattle, with and without supplements

McLennan, Stuart and Poppi, Dennis P. (2012). Application of nutrient requirement systems to grazing cattle, with and without supplements. In: Sebastiao Campos Valadares Filho, M. F. Paulino and Pedro Veiga Rodriguez Paulino, VIII Simpósio de Produção de Gado de Corte. VIII Simpósio Internacional de Produção de Gado de Corte (VIII SIMCORTE), Vicosa, Brazil, (95-122). 7-9 June 2012.

Author McLennan, Stuart
Poppi, Dennis P.
Title of paper Application of nutrient requirement systems to grazing cattle, with and without supplements
Conference name VIII Simpósio Internacional de Produção de Gado de Corte (VIII SIMCORTE)
Translated conference name VIII International Symposium of Beef Cattle Production (VIII SIMCORTE)
Conference location Vicosa, Brazil
Conference dates 7-9 June 2012
Proceedings title VIII Simpósio de Produção de Gado de Corte
Place of Publication Viscosa, Brazil
Publisher Federal University of Viscosa
Publication Year 2012
Sub-type Fully published paper
Open Access Status
Editor Sebastiao Campos Valadares Filho
M. F. Paulino
Pedro Veiga Rodriguez Paulino
Start page 95
End page 122
Total pages 28
Collection year 2013
Language eng
Abstract/Summary Application of the nutrient requirement systems with grazing animals includes several challenges, not the least being the estimation of the intake and nutritive value of the diet under often diverse and continually changing forage systems. However, application also requires confidence by the user that if the nutrient intake can be accurately determined, the nutrient requirement system will then accurately predict the performance of the animal. These challenges are discussed in this paper. Data sets derived from experiments with confined (non-grazing) cattle fed generally lowquality hays of tropical grasses with a variety of supplement types and intakes were used to compare predictions using either the Australian (SCA 1990; CSIRO 2007) or an American (Cornell Net Carbohydrate and Protein System; CNCPS) requirement scheme. Both systems provided reasonably accurate and similar predictions of growth rate of cattle across the wide range in supplement intakes used providing support for their general application in tropical feeding systems. However, estimates of the various components of energy utilisation, e.g., maintenance energy requirements and efficiency of energy use for growth, were substantially different for the two systems emphasising the importance of applying the different systems in totality. A major impediment to field application of the requirements systems is the difficulty in adequately describing the nutritive value of the selected diet, with large inaccuracies associated with pasture sampling to mimic diet selection. In northern Australia and part of southern USA the use of faecal near-infrared reflectance spectroscopy as provided a method of indirectly assessing diet quality from a faecal sample collected from representative animals. Determination of intake by grazing animals has also presented problems and methods of estimating intake based on diet and animal attributes are discussed and evaluated. A method of estimating intake, by back-calculating from liveweight change using the various equations of the requirement schemes, is described and its value for processes such as fodder budgeting is discussed. It is concluded that the various nutrient requirement systems are probably accurate enough for field application, including under tropical and rangeland conditions, and opportunities for the practical application of these systems are suggested.
Q-Index Code E1
Q-Index Status Provisional Code
Institutional Status Non-UQ

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Created: Fri, 12 Apr 2013, 17:09:53 EST by Dr Stuart Mclennan on behalf of Centre for Animal Science