The Influence of Several factors on the Protein and Solids-Not-Fat Content in the Milk of Jersey Cows

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Abstract
Individual cows from two Jersey herds were sampled bi-weekly for a 15-month period to obtain values on the compositional quality of their milk. Mean differences obtained were the fat, protein, total solids, and solids-not-fat content. The morning and evening samples from one of the herds were not significant. A significantly larger quantity of milk was produced at the morning milking. Significant differences between herds were obtained for pounds of milk and percent of fat, protein and total solids. Exposure of one herd to low temperatures in a loose-housing barn may have been a factor in the compositional differences between herds. Seasonal variations were seen, with compositional quality being highest in the winter and lowest in the summer. Milk solids content was inversely related to milk quantity, with lowest solids content during the second month of lactation and highest toward the end of the lactation. The following equations were presented for predicting solids-not-fat (SNF) content from protein or fat content: For herd A, (a) SNF = 8. 33 + 0. 216F, (b) SNF = 6. 92 + 0. 602P; for herd B, (a) SNF = 6. 97 + 0. 465F, (b) SNF = 6. 96 + 0. 589P.