Effect of milking frequency on the hygiene index and nutritional quality of raw milk: Mid-northern region Algerian study

The objective of this study was to determine the effects of reduced milking frequency on nutritional and microbiological cow’s milk quality. Once-Daily Milking (ODM) on a standard diet; 3-Times Daily Milking on a standard diet (TDM) cows were assigned from 06 February to 30 May. Cows were on average 218 days into lactation at the start of the trial, and all cows were managed similarly throughout the trial. Milk yields and gross milk composition of cows on all treatments were measured. Results of this study showed a significant decrease in the average milk nutritional quality in TDM as compared to ODM as fat, lactose, protein, casein rates by 15%, 8%, 3.9% and 5.5% respectively. In addition, TDM decreased the minerals and vitamins levels by 5.8% as compared to milk obtained by ODM. In addition, the application of TDM in the milking affects the milk physical properties by the decrease of the milk conductivity, density and freezing point by 3.29%, 1.07% and 8.1% as compared to ODM milk. Moreover, the practice of TDM affects the milk bacteriological quality by the increase of Total Bacteria Count (TBC) (from 11.6 to 13.8), Total Aerobic Mesophilic Flora (TAMF) (from 6.4 to 7.8); Total Coliforms (TCol) (from 4.6 to 5.7); Fecal Coliforms (FCol) (from 3.2 to 4.2). Additionally, TDM increase significantly the Sulphite Reducing Clostridium (SRC), molds and yeasts count in milk as compared to ODM. In fact, the improvement of hygienic milking conditions through applying good hygiene practices and new techniques has made it possible to reduce the microbial load of the raw milk samples analysed bacterial flora. Therefore, the reduction in milk production in ODM was completely compensated by an increase in the concentration of milk components as fat, lactose, protein, casein, minerals and vitamins rates as compared to TDM.