Effect of the energy level of the diet of Holstein cows in early and mid-lactation on the sanitary and hygienic quality of milk

Abstract

During the first weeks of lactation, the energy balance of dairy cows is generally negative, allowing for decompensation in a variety of tissues and systems, especially the immune system. The energy levels of a cow's diet during the first third of lactation, in specialized dairying, will modulate the immune system functionality of the mammary glands. The aim of this study was to assess the sanitary quality of milk through the somatic cell score (SCS), the colony-forming units (CFU), and the isolated bacteria of Holstein cows with different energy levels in the diet. Thus, 24 Holstein cows were studied during their first third of lactation, after the lactation peak (50 to 100 lactation days). They were assigned into 4 treatments, taking into account the energy requirements of each animal: Isoenergetic (ISO), Hypoenergetic (HYPO), Hyper energetic (HYPER), and Isoenergetic plus sunflower oil supplementation (OIL). Milk samples were taken for the somatic cell count (SCC) and CFUs, and isolated pathogens in milk were identified by microbiological culture. The diet had a significant effect on SCS with a value p of 0.0331, but not on the CFUs (p< 0.5141). 11 pathogens were identified and in 33.9% of samples, microorganisms were not isolated. The Isoenergetic diet favors the presence of some microorganisms and the increase of SCS.