FREQUENZA DELLE CURVE DI LATTAZIONE STANDARD E ATIPICHE PER LATTE, GRASSO, PROTEINE E LATTOSIO IN BOVINE DI RAZZA BIANCA VAL PADANA

ABSTRACT – Frequency of standard and atypical lactation curves for milk, fat, protein and lactose yield in Bianca Val Padana cattle - The aim of the research was to evaluate the frequency and the parameters of standard and atypical lactation curves in Bianca Val Padana (BVP) cattle breed and the effects of some environmental factors on equation parameters. Data from 1636 test day controls of 262 lactations of 88 BVP cows were processed. The data relating to the daily production (kg) of milk, fat, protein and lactose were subjected to regression analysis, by applying the model of Wood in linear form (log yn = log A + B log n + Cn). Limited to standard curves with ADJRSQ >80%, persistence, week at peak and peak production were then calculated. Based on the algebraic sign of the parameters B and C, three different types of lactation curves (standard, decreasing, reversed) have been identified while it has never been detected the ascending type. As regards to daily milk production, the most common type has been the standard (80.53%), followed by reversed (14.12%) and decreasing curve (5.34%), while for the production of fat, protein and lactose, the most common type has been the standard (respectively 55.95%, 70.59%, 80.84%), followed by the decreasing (respectively 25.40%, 24.31%, 13.79%) and by the reversed curve (respectively 18.65%, 5.10%, 5.36%). In conclusion, the study of the characteristics of the lactation curve and the reduction of atypical types could contribute to the qualification of production even in local breeds, helping to safeguard them.