Effect of non-genetic factors on longevity traits in Simmental cows

Abstract

The effects of fixed non-genetic factors (farm, season of birth, year of birth, total number of lactations) and a continuous non-genetic factor (age at first conception) on the expression and variability of longevity traits such as age at culling, length of productive life, days in milk and cow efficiency index were investigated in 2548 Simmental cows in three farming areas. Based on the model used for the analysis of the effects of non-genetic factors, including the environment and cow age at first conception, on the expression and variability of longevity traits, the overall means for age at culling, length of productive life, days in milk and cow efficiency index were 2445.21±17.49 days, 1562.55±17.71 days, 1094.17±12.28 days and 58.68±0.32%, respectively. The effect of farming area, year of birth and lactation group on longevity traits was very significant (P lt 0.01), whereas the effect of season of birth was significant (P lt 0.05). Age at first conception had a highly significant (P lt 0.01) effect on age at culling, length of productive life and cow efficiency index, and no significant effect on days in milk (P>0.05). Based on the model used, the coefficients of determination (R2 ) were very significant (P lt 0.01) for all longevity traits, and ranged from 0.898 for age at culling to 0.959 for days in milk.

Uticaj fiksnih (farma, sezona i godina rođenja, ukupan broj laktacija) i kontinuelnih (uzrast pri prvoj oplodnji) sistematskih faktora na ispoljenost i varijabilnost osobina dugovečnosti kao što su uzrast pri izlučenju, dužina produktivnog života, ukupan broj muznih dana i indeks iskorišćavanja krava proučavan je na uzorku od 2548 simentalskih krava raspoređenih na tri odgajivačka područja. Na osnovu primenjenog modela za analizu uticaja sistematskih faktora okoline i uzrasta krava pri prvoj oplodnji na ispoljenost i varijabilnost osobina dugovečnosti opšti prosek za uzrast pri izlučenju, dužinu produktivnog života, ukupan broj muznih dana i indeks iskorišćavanja krava iznosio je 2445,21±17,49 dana, 1562,55±17,71 dana, 1094,17±12,28 dana i 58,68±0,32%. Uticaj odgajivačkog područja, godine rođenja i grupe laktacija na osobine dugovečnosti bio je vrlo značajan (P lt 0.01), dok je uticaj sezone rođenja krava bio značajan (P lt 0.05). Uzrast pri prvoj oplodnji visoko značajno (P lt 0.01) je uticao na uzrast pri izlučenju, dužinu produktivnog života i indeks iskorišćavanja krava, dok na ukupan broj muznih dana nije imao značajan uticaj (P>0.05). Dobijeni koeficijenti determinacije (R2 ), na osnovu primenjenog modela, za sve osobine dugovečnosti bili su vrlo značajni (P lt 0.01) i kretali su se od 0,898 kod uzrasta pri izlučenju do 0,959 kod ukupnog broja muznih dana.