Causes of variation in production of holstein herds in the state of Santa Catarina, Brazil: Lactation period
Thaler-Neto, A.; Neiva, R.-Santoro; Oliveira, A.-Ilson, G.D.; Martines, M.-Luiz; Falco, J.-Egmar
Revista da Sociedade Brasileira de Zootecnia 24(1): 117-125
Data for 1,119 lactation period from 18 Holstein herds were analyzed. The mean standard error, and coefficient for variation for lactation periods were 281.13 +- 2.03 days and 17.06%, respectively. Herd-year of parturition affected significatively the lactation period and was the main source of variation. Calving season influenced the lactation period. Lactations started on summer and autumn were significantly longer than those starting in the spring. Calving age showed a linear effect on lactation period. The lactation period decreased 0.27 days per month of age. Genetic group of the cow have not significant effect on the lactation period. The lactation period decreased 0,27 days per month of age. Genetic group of the cow had no significant effect on the lactation period.