Resumen

BRINEZ, Wilfido José et al. Some composition parameters and quality on raw milk of dual purpose cows in the machiques county. Zulia State, Venezuela. Rev. Cient. (Maracaibo) [online]. 2008, vol.18, n.5, pp.607-617. ISSN 0798-2259.

The aim of this research was to evaluate the effect of lactation stage, breed, year season and parity number on milk yield (MY), cryoscopy (CR), pH, acidity (TA), total protein (TP) and casein (CA) in raw milk of an herd of dual purpose. An evaluation was performed in 926 milk samples for the evening milking of a herd of dual purpose cattle (Holstein, Brown Swiss, Creole Zebu and Mosaic) maintained in a semi-intensive production system in Machiques, Zulia State, Venezuela. Cows were grouped according to the breed (6 groups), lactation stage (1 to 90 days, 91 to 180 days and > of 181 days) and parity number (1, 2, and 3 or more parturitions). Cows were sampled during a year period, including two seasons (dry of November to March and rainy of April to October). Data were analyzed through the statistical package SAS, using a variance analysis by testing mean differences through least square means procedure. In addition, Pearson product moment correlation analysis was performed. Overall means were for MY 3.109 Kg, CR -0.541, pH 6.72, TA 17.60 ml of NaOH 0.1 N/100 ml of milk, TP 3.66% and CA 2.40%. Statistical differences were observed (P<0.05) for breed and lactation stage in all the variables studied. However, year season only had effect on CA. On the other hand, parity number had effects on Y, TP, and CA. Significant correlation coefficients were found among MY with CR, TP and CA, of the pH with TA, and TP with CA. It is concluded that the breed and lactation stage represent the factors that introduce greater variation in the quality and protean composition of the raw milk of dual purpose cows.

Palabras clave : Composition; quality; milk; dual purpose.

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