Influence of Electrical Conductivity, Days in Milk and Parity on Milk Production and Chemical Composition

The aim of study was to assess milk production and chemical composition during the first 100 days of lactation, under the influence of electrical conductivity, parity and days in milk. Study was conducted at Research and Development Station for Bovine Arad, on 66 Romanian Spotted cows (20 primiparous, 46 multiparous). Significantly higher values (p≤0.017) of electrical conductivity were recorded for primiparous (10.15±0.09 mS/cm) compared with multiparous (8.79±0.15 mS/cm). During the first 30 DIM electrical conductivity was higher (9.7±0.12 mS/cm) than for 31 to 60 DIM (9.04±0.12 mS/cm; p≤0.001) and for 61 to 100 DIM (8.17±0.11 mS/cm, p≤0.001). Multifactorial regression model applied highlights significant influence of month of calving (p≤0.001) and DIM (p≤0.034) on the electrical conductivity, while parity had no influence (p>0.36). Medium and negative correlations were calculated between electrical conductivity and some chemical components (fat R=-0.15, protein R=-0.13), while to milk production correlation was positive (R=0.12). No significant correlations were obtained according to lactose content (R=-0.013). Dynamics of milk production and chemical composition have been significantly influenced by month of calving (p≤0.001), DIM (p≤0.001) and parity (p≤0.002). This study found no significant influence of milk electrical conductivity on milk production or chemical composition (p>0.59).