Occurrence of unstable non-acid milk in dairy farms in northern Tocantins state, Brazil

Résumé

The diagnosis of unstable non-acid milk (UNAM) in Brazil is overlooked due to the lack of information about this problem available to dairy farmers, mainly in the North region of the country. This report describes the occurrence of UNAM in three dairy farms of family farmers in northern Tocantins state, Brazil, who use animal feed based on Urochloa brizantha without mineral supplementation. The animals had been subjected to a poor feeding practice, with low quantity and quality, due to the dry period in the region and inappropriate nutritional management. Fourteen animals that presented alterations in milk characteristics were subjected to 72% alizarol test, California mastitis test, strip cup test, somatic cell count (SCC), boil test, physical-chemical and microbiological analyses, and search for undesirable substances. The time of lactation, udder health, and serum glucose level of animals, and soil and forage quality were also evaluated. The results showed 42% animals diagnosed with mastitis, 21% of them with clinical and 21% with subclinical mastitis; and 78% of animals with samples positive for the alizarol and boil tests, and Dornic acidity between 14° and 18°, characterizing positive cases for UNAM. Only one animal presented SCC above the limit established by the Brazilian legislation. The animals presented undamaged teats and no alteration in glycemia. Changes in nutritional management were recommended and done and the alizarol tests were redone after 14 days, showing all negative results for UNAM. The conclusion is that incorrect nutritional management is the main cause of UNAN in the studied cases.