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Revista Brasileira de Zootecnia

On-line version ISSN 1806-9290

Abstract

HENRIQUES, Lara Toledo et al. Evaluation of non-linear models and the effects of primiparous cows and calves intake on the lactation curve of Nelore cows. R. Bras. Zootec. [online]. 2011, vol.40, n.6, pp.1287-1295. ISSN 1806-9290.  http://dx.doi.org/10.1590/S1516-35982011000600018.

This research was carried out to evaluate five non-linear mathematical models to describe lactation curves of Nelore cows and effect of the cow and calf intake on milk yield. In this study we compared the models of Sikka (1950), Nelder (1966), Wood (1967), Jenkins & Ferrell (1984) and Jenkins & Ferrell (1984) with a fit parameter. Data of production were collected from 12 primiparous cows with a mean live weight of 359 kg (± 8) and its offspring. The milk production was estimated weighing the calf before and after suckling, from birth to 180 days of age. Measurements were made twice a day in a weekly period after 6 hour fasting of liquid and solids. The mathematical models of Sikka, Jenkins & Ferrell, Nelder and Wood failed to describe lactation curve appropriated due to over or underestimation of milk yield peak. Better adjustement was found for the model of Jenkins & Ferrell with a fitting parameter. Cow and calf intake evaluated separately was no correlated with milk yield. Conversely at evaluating both cow and calf together, it was found a positive and a negative correlation with milk yield, respectively. Milk yield is is closely correlated wiht cow and calf intake, and the capacity of the calf to ingest non-dairy solids results in reduction of milk needs from dam.

Keywords : milk production; persistency.

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