Protein concentrations in cows’ milk during the four stages of lactation

(1) North Bay Haven Charter Academy, Panama City, Florida

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Proteins play an essential role in the growth and development of young calves, and changes in the nutritional needs of these calves may be responsible for changes in milk protein concentrations across the four stages of bovine lactation. The purpose of this research was to analyze the fluctuations in the concentrations of casein and whey, which are the two primary sources of protein in cows’ milk. Milk proteins provide essential nourishment for young calves, so we hypothesized that the total protein concentration of the milk would decline from the first stage of lactation to the fourth stage of lactation. Absorption spectroscopy was used to determine the concentration of the proteins in the milk, and five trials were conducted for each stage of lactation. A spectrometer was used to collect absorbance data for the whole milk, casein, and whey samples, and a standard curve was used to convert those absorbance readings into concentration values. The hypothesis for this research was supported in that the total protein concentration of the milk declined from the first stage of lactation to the fourth stage of lactation. More specifically, the concentration of casein proteins decreased as the concentration of whey proteins increased. These trends are important because they provide a foundation for future research to determine whether the observed fluctuations in the protein concentrations are significant enough to pose implications for individuals suffering from lactose intolerance.

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