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Staff Publications

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    'Staff publications' is the digital repository of Wageningen University & Research

    'Staff publications' contains references to publications authored by Wageningen University staff from 1976 onward.

    Publications authored by the staff of the Research Institutes are available from 1995 onwards.

    Full text documents are added when available. The database is updated daily and currently holds about 240,000 items, of which 72,000 in open access.

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Record number 309958
Title On the use of simple ratios between lactation curve coefficients to describe parity effects on milk production
Author(s) Friggens, N.C.; Emmans, G.C.; Veerkamp, R.F.
Source Livestock Production Science 62 (1999)1. - ISSN 0301-6226 - p. 1 - 13.
DOI http://dx.doi.org/10.1016/S0301-6226(99)00110-4
Department(s) ID Lelystad, Institute for Animal Science and Health
Publication type Refereed Article in a scientific journal
Publication year 1999
Abstract The objective of this study was to quantify how the pattern of milk production relative to time from calving is affected by parity in cows fed high quality rations. For this purpose two models; those of Emmans and Fisher (1986) and Dijkstra et al. (1997), were considered. Comparison with Wood's (1967) function was made to evaluate their fitting ability. Daily records of milk yield from 40 cows fed a grass silage based, high concentrate total mixed ration were used. The cows had ad libitum access to food, they were milked twice daily. Each of the cows had milk yield records from calving to 240 days post calving in parities 1, 2 and 3. The model of Dijkstra et al. (1997) was found, on inspection, to be an alternative parameterization of the Emmans and Fisher model (1986). In the analyses, the Emmans and Fisher form was used: Yield = aU exp [-c(days from calving)] where U = exp {- exp (G0 -b[days from calving])}. The Emmans and Fisher model (1986) performed marginally better than the Wood's function (1967) in terms of percentage of variance accounted for and residual standard error. There was no significant effect of parity on G0 or b, which are the main parameters describing the evolution of lactation to peak. However, there was a highly significant effect (P < 0.001) of parity on coefficients a, the scalar, and c, the decay coefficient. The coefficient values in parity 1 and 2 were found to be a constant proportion of the values in parity 3. Parity effects can therefore be described by simple ratios, offering the possibility of simplifying the inputs needed in models to describe potential milk production.
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