Avaliação de caracteristicas de produção e reprodução de grupos genéticos holandês x gir de um rebanho leiteiro no município de horizonte - ce

Abstract

The objective of this was to evaluate milk yield per lactation (PL), milk yield per day of lactation (PD), lactation length of (DL), milk yield in 305 days (PL305), milk yield per day in 305 days of lactation (PD305), milk yield of calving intervals (PIP), milk yield in 305 days of calving intervals (PIP305), calving intervals (IP) and age at first calving (IPP). The records were obtained of 175 cows of the Farm Forquilha, located in the country of Horizonte, in the state of the Ceará, Brazil, in a total of 507 lactations, being 344 multiparous and 163 primiparous cows. Data were analyzed through the least square method by GLM procedure (SAS, 1999). Three statistic models were used. The first model used for multiparous animals included the effects fixed of genetic group, season and year of calving, lactations numbers and origin of the father of the cow (bull or semen). The second model excluded the effect of lactations numbers for primiparous. The third model was for analysis of the age at first calving included the genetic group, month and year of birth and origin of the father of the cow. Certain genetic groups had better performance according to some criteria, while other groups had better responses as regard to other traits. Thus, further studies are needed to better determine the characteristics of those genetic groups, including economic evaluations. The effect year of calving significantly influenced all characteristics related to production and reproduction, for both primiparous and multiparous cows. Such results support the direct influence of changes in management throughout the study, also demonstrating the importance of proper management strategies and the balance of all factors that form the production system: animal (genotype), management (health, nutritional and reproductive), welfare and housing. In summary, all such criteria are even more crucial to the production system than the definition of the genetic group itself.