Determination of factors affecting 305-day milk production via path analysis on holstein friesians [Siyah alaca sığırlarda 305 günlük süt verimini etkileyen faktörlerin path (iz) analizi İle belirlenmesi]

A quantitative trait was affected directly or indirectly by several factors due to relationships among them. it is necessary to identified direct and indirect effects of a factor to reveal all relationships in a detailed way. in this study,total of 11647 305-day milk yield records from the 7 parities of 5047 holstein friesian cows were statistically evaluated for determining direct and indirect effects of parity (x1),year of calving (x2) and lactation length (x3) on 305-day milk production (y) via path analysis. correlations among 305 day milk yield,parity,year of calving and lactation length were calculated 0.17,0.43,0.54 respectively and found statistically significant ((p<0.01). the direct effects of the parity,year of calving and lactation length on 305-day milk production were found py1=0.12,p21=0.10,p31=0.46 respectively and statistically significant (p<0.01). the indirect u effect of parity via year of calving and s effect via lactation length on 305 day milk yield were found 0.01 and 0.04,respectively. the indirect u effect of year of calving via lactation length and s effect via parity on 305 day milk yield were found 0.31 and 0.02,respectively. moreover,the indirect u effect of lactation length via year of calving and s effect via parity were found 0.07 and 0.01,respectively and lower. © 2015,kafkas university. all rights reserved.