The effect of age at first insemination on longevity and lifetime production traits in simmental cows

Abstract

The effect of cow age at first insemination on longevity and lifetime production traits was examined in the Simmental cows housed at the "Zlatiborski Suvati" (Mt. Zlatibor Pastures) farm. The general linear model was used to calculate linear regression coefficients for the effect of age at first insemination on longevity traits including the age at culling, the length of productive life, the total number of milking days and the cow utilization index as well as on lifetime production traits being lifetime milk production, the milk fat content of the lifetime milk production, lifetime milk fat production, lifetime production of 4% fat-corrected milk and milk production per milking, productive and lifetime day. Based upon the calculated linear regression coefficients, the age at first insemination had a very high significant effect (P lt 0.+001) on the age at culling and the cow utilization index (bxy=1.386 and bxy=-0.020) and no significant influence (P>0.05) on other longevity traits. Cow age at first insemination had no significant effect (P>0.05) on the lifetime milk and milk fat production traits.

Uticaj uzrasta krava pri prvoj oplodnji na osobine dugovečnosti i životne proizvodnje ispitivan je kod krava simentalske rase smeštenih na farmi "Zlatiborski suvati". Opštim linearnim modelom izračunati su koeficijenti linearne regresije uticaja uzrasta pri prvoj oplodnji na osobine dugovečnosti kao što su uzrast pri izlučenju, dužina produktivnog života, ukupan broj muznih dana i indeks iskorišćavanja krava i osobine životne proizvodnje me|u kojima su životna proizvodnja mleka, sadržaj mlečne masti životne proizvodnje mleka, životna proizvodnja mlečne masti, životna proizvodnja 4% masnog mleka i proizvodnja mleka po muznom, produktivnom i životnom danu. Na osnovu izračunatih koeficijenata linearne regresije uzrast pri prvoj oplodnji vrlo visoko značajno je uticao (P lt 0.001) na uzrast pri izlučenju i indeks iskorišćavanja krava (bxy=1.386 i bxy=-0.020), dok na ostale osobine dugovečnosti nije imao signifikantan uticaj (P>0.05). Uzrast krava pri prvoj oplodnji nije imao značajnog uticaja (P>0.05) na osobine životne proizvodnje mleka i mlečne masti.