Variability of milk protein fraction in dairy herds of state of São Paulo / Variabilidade de frações protéicas do leite em rebanhos leiteiros do estado de São Paulo

AUTOR(ES)
DATA DE PUBLICAÇÃO

2008

RESUMO

The objective of this experiment was to study the variability of the true protein of milk produced in dairy herds of Sao Paulo State, under the influence of milk somatic cell count, breeds, season of the year and production system. For this aim, fifty commercial herds were selected; these herds were divided by breeds in: 17 Holstein, six Jersey, and 26 Girolando. Milk samples from the bulk tank were collected monthly and were analyzed to determine milk somatic cell count (SCC) and milk composition by the automatic method and to determine the true protein of milk (TP) by Kjeldahl method. The total nitrogen was multiplied by a factor of 6.38 to express the results in crude protein (CP) basis. True protein of milk was determined by the equation (TP = CP - NPN). No significative effect were observed for season of the year, breed, SCC and system of production were observed and this fact aloud a confection of one equation to predict milk true protein: PV = 0,1862+(1,0869 x PB) - (1,2895 x NNP) + 0,0687, com R2 = 0,82 . The use true protein of milk instead of crude protein, like it is still used in Brazil, will increase the accuracy of protein testing, and will improve substantially the milk payment system.

ASSUNTO(S)

milk. payment system season dairy cattle breed proteínas do leite sazonalidade. true protein bovinos leiteiros preço agrícola raças animais

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