Efecto del Grupo Racial y Algunos Factores no Genéticos sobre la Producción de Leche e Intervalo entre Partos en Vacas de Doble Propósito

in order to establish the effect of breed group and some non-genetic factors on milk production corrected at 244 days (p244) and also on calving interval (iep), 9469 and 6288, observations were analyzed, respectively. the animals were at grazing and milked twice daily. the statistical model included effects of: farm (f: 1,2); year of birth (ap:1995-2005) for p244, and (ap: 1995-2004) for iep; month of birth (mp: 1, ？ 12), lactation number, (nl: 1...6 or more), breed group: mostly cebu (≥ ？ bos indicus); mostly european (≥ ？ bos taurus); 50% holstein-50% zebu; 50% brown swiss-50% cebu and dairy crossbred mosaic (gr:>cebu, >e, h50cb50, ps50cb50, ml) and the interactions fxap, fxgr, fxnl, apxmp, apxnl. all studied factor affected p244d and iep, except the month of birth which, was not significant for p244. the average p244 and iep were 1744 kg and 466 d, respectively. the differences between the best and worst year for p244 and iep were 275 kg and 141 d, respectively. the gr with the higher milk production and highest iep was ps50cb50 with 1844 kg and 487 d, respectively. as well, gr with the lower production and lowest iep was > cebue with 1619 kg and 452 d, respectively. the difference for p244 and iep between the first and fifth sixth lactation was 181 kg and 20 d, respectively. there was difference between the two farms of 84 kg and 22 d for p244d and iep, respectively. it is interesting to note that fxgr interaction was significant (p<0.01), indicating that gr performed differently on each farm. it can be concluded that the non-genetic effects and gr have a high influence on the p244 and iep.