PORCENTAGEM DE LACTOSE EM AMOSTRAS DE LEITE DE TANQUE NO ESTADO DO PARANÁ

Management of dairy herds programs has used the percentage of lactose in assessing the quality of milk. The effects of the environment on % lactose samples collected monthly by the tanks of the State of Parana dairy industries, analyzed by the Laboratory's Quality Milk (LQL) of Parana Association of Cattle Breeders of Holstein (APCBRH) were evaluated as a result of the agreement with UFPR. We analyzed 1,950,034 milk samples collected from January 2005 to April 2012, in ten regions of the state. The estimated averages, standard deviations and coefficient of variation for% Lactose, ECS and Sample Age in days were: 4.40 ± 0.23, 4.61%; 4.83 ± 1.52, 30.06%; and 2.98 ± 1.57 days, respectively. All the variables included in the mathematical model (month and year of analysis, region, age of the sample and score the somatic cell count) significantly influenced (P <0.01) the variable studied. The R ² of 0.23% was estimated for % lactose. The largest observed values of % lactose occurred in the months of August and September (4.48) and (4.48) respectively, lower in April and May (4.37) and (4.36). The effect of year recorded a linear increase from 2005 (4.38) to 2012 (4.49). For the effect of region, the highest averages occurred in the Southwest region - Francisco Beltrao (4.50) and East Central - Ponta Grossa (4.46), however, the lowest were observed in the North Pioneer - Cornelio Procopio (4 , 40) and Southeast - Irati (4.40). The age of the sample was characterized with the highest average 2 days (4.44), but the lowest value was observed for 6 days (4.42). The% lactose, and had a high negative correlation with the ECS (-0.420) (P <0.01) to vary from zero to eight to% lactose decreased from 4.63 to 4.14%.