Prevention of Churning During Shipment of Dairy Herd Improvement Milk Samples1

Abstract

Polystyrofoam shipping containers used in some DHI central milk testing programs were inadequate to keep fifty 28.3-ml milk samples below 10 C for 1 h when transferred into air at 25 C. Initial milk temperature was 4.4 C. Forty samples in a modified shipping container, packed with 850 g of ice, were at 17 C in 24 h. Unless refrigerated shipment can be assured, samples in plastic bags, sealed to eliminate air, should be adopted to minimize fat losses from churning as measured by a Mark III Milko-Tester. Fat losses increased with increasing air space in containers, absence of dichromate preservative or phosphate additives, and agitation above 10 C. Churned fat losses were greater in mishandled Jersey milk (high fat) than in Holstein milk (low fat) samples.