Comparative evaluation of a new lactation curve model for pasture-based Holstein-Friesian dairy cows

Adediran, S.A., Ratkowsky, D.A., Donaghy, D.J., and Malau-Aduli, A.E.O. (2012) Comparative evaluation of a new lactation curve model for pasture-based Holstein-Friesian dairy cows. Journal of Dairy Science, 95 (9). pp. 5344-5356.

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Fourteen lactation models were fitted to average and individual cow lactation data from pasture-based dairy systems in the Australian states of Victoria and Tasmania. The models included a new "log-quadratic" model, and a major objective was to evaluate and compare the performance of this model with the other models. Nine empirical and 5 mechanistic models were first fitted to average test-day milk yield of Holstein-Friesian dairy cows using the nonlinear procedure in SAS. Two additional semiparametric models were fitted using a linear model in ASReml. To investigate the influence of days to first test-day and the number of test-days, 5 of the best-fitting models were then fitted to individual cow lactation data. Model goodness of fit was evaluated using criteria such as the residual mean square, the distribution of residuals, the correlation between actual and predicted values, and the Wald-Wolfowitz runs test. Goodness of fit was similar in all but one of the models in terms of fitting average lactation but they differed in their ability to predict individual lactations. In particular, the widely used incomplete gamma model most displayed this failing. The new log-quadratic model was robust in fitting average and individual lactations, and was less affected by sampled data and more parsimonious in having only 3 parameters, each of which lends itself to biological interpretation.

Item ID: 35611
Item Type: Article (Research - C1)
ISSN: 1525-3198
Keywords: lactation model, pasture-based, dairy cow, test-day milk yield
Funders: Dairy Australia (DA), Tasmanian Institute of Agriculture (TIA), University of Tasmania (UTAS)
Date Deposited: 01 Oct 2014 15:50
FoR Codes: 07 AGRICULTURAL AND VETERINARY SCIENCES > 0702 Animal Production > 070201 Animal Breeding @ 80%
06 BIOLOGICAL SCIENCES > 0604 Genetics > 060412 Quantitative Genetics (incl Disease and Trait Mapping Genetics) @ 20%
SEO Codes: 83 ANIMAL PRODUCTION AND ANIMAL PRIMARY PRODUCTS > 8303 Livestock Raising > 830302 Dairy Cattle @ 100%
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