Factors effecting the lactation curve parameters of Brown Swiss and Jersey cows in Türkiye

The explanatory capacity of the lactation models depends on the successful prediction of the lactation process and the regulation of environmental factors affecting production parameters. Therefore, in this study, six different lactation curve models (Wood, Wilmink, Sikka, Gou and Swalve, Nelder and Cobby and Le Du) were used to compare lactation milk yield data in individual monthly interval. Yield records in the first five lactations (1-5) were used a total of 61525 lactations data belonging to 22955 Brown Swiss (BS) and 5178 Jersey (JR) cows. Except for the Cobby and LeDu curve model, the explanatory capacity for the lactation curve models of the other models was quite high and the adjusted R2 (between 0.95 and 0.99) and RSD (between 0.97 and 1.03) were found to be close to the others. Observed and estimated milk yield had higher milk yield in EU origin BS cows, while TR origins had higher milk yield in JR cows (P