Erzurum İlinde Yetiştirilen Esmer ve Siyah Alaca İneklerin Bazı Reprodüktif Performansları ve Ayıklama Nedenleri Üzerine Bir Araştırma

The aim of this study was to determine the reproductive performance and culling reasons by using some  reproductive  records  of  165  Brown  Swiss  and  Holstein  cows,  between  2008-­‐2013  years.  Ages  at  first  breeding  of  heifers  in  Browns Swiss and Holstein breeds were determined as 728 and 712 days, respectively. The numbers of artificial  insemination for each pregnancy were 1.54 for Brown Swiss and 1.58 for Holstein breed and the herd’s mean was  calculated  as  1.56.  Service  period  and  calving  interval,  determined  for  the  Brown  Swiss  and  Holstein  cows  were  114  and  116  days;  397  and  393  days,  respectively  and  it  is  found  that,  the  breed  of  cow  and  the  parity  had  no  significant  effect  on  these  two  traits  (P>0.05).  Within  the  herd,  the  productive  lives  calculated  for  the  Brown  Swiss  and  Holstein  breeds  were  2.7  and  1.8  years,  respectively.  For  all  ages,  it  was  determined  that  the  most  important  reason  for  the  culling  was  low  production  level  of  the  cows.  In  young  cows  (2-­‐5  years  old),  it  was  obtained  that  the  involuntary  culling  was  originated  mainly  from  reproductive problems. As a result of the study, it is concluded that, the economic profit of the herd might have been  affected  adversely  by  the  age  at  first  breeding  of  heifers  such  that  it  was  quite  high  and  the  reproductive  life  of  cows  were  too  short  in  Holstein  breed.  Key  words:  Brown  Swiss,  Calving  Age,  Calving  Interval,  Culling,  Holstein  Friesian.