массовая доля белка

Selection and genetic parameters of productive traits and exterior features of black-and-white cattle in Western Siberia

The article presents materials on the selection and genetic indicators of black-and-white cattle. The amount of repeatability allows for selection by productive qualities already in the first lactation. There was a significant negative moderate relationship between the mass fraction of fat and milk yield for 305 days of lactation (- 0.308; Р>0,999). There is a tendency of negative weak dependence between the milk yield and the mass fraction of protein, namely, the increase in milk yield is accompanied by a slight decrease in protein content.

The comparative characteristic of the milk quality indicators at the breeding farms of the Totemskiy district in the Vologda region (taking into account the seasonality)

The article presents the results of studies devoted to the milk quality indicators: mass fat fraction, mass protein fraction, mass fraction of solids non fat, somatic cells in modern breeding farms of the Totem district in the Vologda region. In 2019 the quality milk indicators were determined from cows in the “Rodina” SPK (collective farm), the “Totemskiy” SPK and the “Velikodvorye”collective farm. Based on the data obtained the research was formed, the comparative characteristic of the milk quality indicators was carried out taking into account the season of the year.

Milk quality of Ayrshire breed cows (Prilutsky type) depending on a season and a keeping way

The article presents the results of the season study influencing the on the milk quality of Ayrshire breed cows (Prilutskiy type). It is established that regardless of the keeping cows the protein and fat content in milk of Ayrshire breed cows (Prilutskiy type) at the «Agrofirma Red Star» tends to decrease in summer. Regardless of the season the somatic cell indicators in cow’s milk are lower in 1.73-2.03 times when loose housing and milking in the parlor compared with the tethered housing and milking in the stalls.

Influence of the season on the mass fraction of protein and urea in the milk of cows of black and motley breeds with different methods of maintenance and milking technologies

The article presents the results of studies on the urea content and the mass fraction of protein in the milk of cows with a tethered and loose method of maintenance, taking into account the technology of milking cows, depending on the season. The optimum content of urea, protein in cow’s milk is established in summer period, the greatest one is revealed in winter period with all milking methods and maintenance technologies

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