Spatial characterization of hygienic-sanitary indicators of refrigerated raw milk from three microregions of the Rondonia state

Bacterial count (SPC) and somatic cell count (SCC) are considered universal indicators of milk quality. The objective of this study was to identify SPC and SCC clusters in milk samples from three microregions of the state of Rondonia and to evaluate the influence of year period and tank type on these indicators. A total of 566 milk cooling tanks linked to dairy industries with the Federal Inspection Service located in the Ariquemes, Ji-Parana and Porto Velho microregions were evaluated. The SPC and SCC results of the tank samples and the geographical coordinates were obtained from the dairy industry database; the study focused on the results of official analyses carried out by the Laboratories of Milk Quality accredited to the Ministry of Agriculture, Livestock and Food Supply (MAPA) in 2015, constituting a pool of 6,792 data subsets from 2,209 farmers. To elaborate the spatial distribution maps of the quality indicators, the ArcView 3.1 (R) software was used. Spatial dependence was evaluated by geostatistics, using the ordinary kriging method for data interpolation. Variance analysis (ANOVA) was performed using the SAS 9.0 GLM procedure on the logarithmic transformation of SCC and SPC, using as variables the type of tank (individual and collective) and season (dry and rainy). The frequency of milk quality adjustments to the limits defined in the legislation has shown that SPC is a major challenge for the state's production chain. There were no significant differences in this frequency for SCC and SPC, neither between the microregions studied, nor between the dry and rainy season (p > 0.05). The analysis of variance considered the period of year and type of cooling tank and showed higher SPC and SCC in the rainy season (p < 0.05); SCC and SPC were higher in collective tanks used by more than 5 farmers (p < 0.05). Spatial dependence was weak for SCC (DD = 22.02) and moderate for SPC (DD = 25.93), indicating the Machadinho do Oeste region as a priority area for mastitis control, and the Ariquemes microregion and west of the Porto Velho microregion as areas of high SPC. The results demonstrated the feasibility of spatial analysis as a tool for evaluating of refrigerated raw milk quality indicators and may support the definition of public and private strategies and policies to improve the milk quality and legislation adequacy.