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Empirical algebraic modelling of lactation curves using Irish data
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2005
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N. Quinn, L. Killen, F. Buckley. (2005), Empirical algebraic modelling of lactation curves using Irish data. Irish Journal of Agricultural and Food Research, 44: 1–13
Abstract
The purpose of this study was to find a well-fitting, robust, single-equation model to
describe the shape of lactation curves for Irish dairy cows. The suitability of a number
of algebraic models that depict lactation curves was examined, using Irish test day
data. The analysis was carried out on a total of 14,956 lactation records from commercial
and experimental herds and included both autumn and spring calving animals.
‘Goodness of fit’ and adherence of the various models to the assumptions of
regression analysis were examined. Multicollinearity posed a severe problem in the
application of the best-fit model but omitting one of the variables from the estimation
procedure reduced this effect. The modified model, referred to as the Ali-B model, is a
single equation model that can be easily updated and incorporated into computer code.
This is in contrast with the Standard Lactation Curve (SLAC) method, a method of
interpolation, which is currently used by the Irish industry. The effects of seasonal
factors on milk production were estimated and added to the Ali-B model to create a
production profile for cows calving in specific months. The Ali-B model provided an
acceptable level of accuracy in representing the shape of the lactation curve for Irish
dairy cows, and can be easily modified for different environmental scenarios.