Investigation of electrical conductivity of milk in robotic milking system and its relationship with milk somatic cell count and other quality traits

The scientific research was carried out at Lithuanian University of Health Sciences, Veterinary Academy, state enterprise “Pieno tyrimai”, as well as in dairy farms running automatic voluntary (robotic) milking systems in Lithuania. A total data set of 462574 cow milking records was assessed in the research. The objectives of this investigation were to evaluate the milk electrical conductivity indicator from robotic milking system and to assess the genetic correlation with the indices collected in a database of Lithuanian dairy cattle, to estimate heritability coefficient using multiple traits mixed linear model with permanent environment effects. The research has shown, that the electrical conductivity of milk ranged from 4.6 to 5.8 ms/cm in milk samples where somatic cell count did not exceed 200 thousand/ml and variation in electric conductivity of milk can be treated as one of the main parameters for cows’ health monitoring system. A high coefficient of heritability of electrical conductivity of milk (h2 = 0.512 ± 0.028; p < 0.001) and a very low coefficient of heritability of somatic cell count (h2 = 0.032 ± 0.014; p < 0.001) was determined. The results of the research have also revealed a positive genetic correlation of electrical conductivity with milk somatic cell count (rg = 0.332 ± 0.016; p < 0.001). Electrical conductivity of milk from robotic milking system can be introduced as an indicator of mastitis prevention in dairy cows and genetic selection based on this trait may be possible