Variability of Milk Components in 1705 Herds

Area of Science:

• Dairy Science
• Animal Science
• Food Science

Background:

• Milk pricing programs often focus on specific components like fat.
• Understanding the variability and relationships between milk components is crucial for accurate pricing.
• Seasonal and grading factors can influence milk composition.

Purpose of the Study:

• To analyze milk components (fat, solids-not-fat (SNF), protein, total solids (TS), aerobic plate count) over a year.
• To evaluate these components as factors in milk pricing.
• To investigate the relationship between milk grade and composition.

Main Methods:

• Biweekly milk samples from 1705 herds over one year (1984).
• Analysis of milk composition: fat, SNF, protein, TS, and aerobic plate count.
• Statistical analysis including coefficient of variation and correlation coefficients.

Main Results:

• Average composition: 3.71% fat, 8.64% SNF, 3.28% protein, 12.35% TS, 1.8 × 10^5 CFU/ml.
• Fat was the most variable component; concentrations were lowest in summer and highest in winter.
• Grade A milk had lower bacterial counts and higher SNF/TS than manufacturing grade milk; fat and protein levels were similar.

Conclusions:

• Milk component concentrations exhibit significant seasonal variation and inter-correlations.
• Solids-not-fat (SNF) pricing requires consideration of producer grade, season, and fat content for accurate protein equivalency.
• Current SNF premium bases may not accurately reflect protein content across different herd fat levels.