Longevity of high-yielding cows

Abstract

Population of Black and White cattle has high genetic potential for production of milk. It exists in very complex production conditions where problems occur which are often manifested in different health disorders, high percentage of culling and short productive life. Longevity parameters are calculated within defined time limits. Bottom limit is determined by date of birth, and top limit by date of culling. The knowledge of the strength of the influence of environment on the longevity of high yielding cows is important from the aspect of its inclusion into the model. According to individual significance of systematic factors, their objective assessment was carried out in order to evaluate the obtained results as precise and correct as possible. Previous studies of the average age of cows at culling from the herd indicated relatively short productive life and life in general of high yielding cows, which due to high percentage of culling effects the herd remount. Consequently selection differential is reduced and in this way realized selection effect is diminished. Objective of this paper was to investigate using appropriate methodology the longevity of high yielding Black and White cows of different genotypes through major systematic influences. Investigated cows according to their origin belong to European type of Black and White cattle in final stage of intensive improvement using Holstein-Friesian breed. Investigated sample included 331 cows. Average age of cows at culling is 2265±463.26 days or 6.21±1.27 years. Observed by cow genotypes, mean values varied from 2140.99 days (> 73% HF), 2247.51 days (58-73% HF) to 2406.97 days ( (lt) 58% HF). Average lifetime production was realized at the level of 25002.66±7755.39 kg of milk with 3.61±0.01% of milk fat.Bulls, sires of cows, class of HF genes and year of culling had highly significant effect (p≤0.01), whereas the effect of reason for culling was significant (p≤0.05) for life duration of cows.

Efikasno korišćenje krava u intenzivnoj proizvodnji potrebno je da traje što duže. Vreme trajanja perioda od njihovog prvog teljenja do izlučenja iz stada treba da omogući poboljšanje ukupne životne produktivnosti. Ovo bi, pored smanjenja troškova sa manjim udelom amortizacije u ceni koštanja, omogućilo bolje ukupne selekcijske rezultate preko nižeg remonta stada uz veći selekcijski diferencijal. Mnogo veća pažnja mora se posvetiti vremenu korišćenja krava u proizvodnji i uzrocima njihovog izlučenja. Najčešći uzroci izlučenja su: slaba mlečnost, smetnje u plodnosti, poremećaji posle teljenja, oboljenja nogu, bolesti organa za varenje, mastitis i dr. Značajan broj istraživanja prosečne starosti krava pri izlučenju iz stada ukazuje na relativno kratak proizvodni i životni vek visokomlečnih krava. On se ispoljava preko visokog procenta izlučenja koji posledično utiče na veći remont stada. Cilj ovog rada je da se primenom odgovarajuće metodologije ispita dugovečnost visokomlečnih crno-belih krava različitih genotipova preko najvažnijih sistematskih uticaja. Ispitivane krave svojim poreklom pripadaju evropskom tipu crno-belih goveda koje se nalaze u završnoj fazi intenzivnog oplemenjivanja holštajn-frizijskom rasom. Ispitivani uzorak uključio je 331 kravu. Prosečna starost krava kod izlučenja iznosi 2265±463.26 dana ili 6.21±1.27 godina. Posmatrano po genotipovima krava srednje vrednosti su bile 2140.99 dana (> 73% HF), 2247.51 dana (58-73% HF) i 2406.97 dana ( (lt) 58% HF). Prosečna životna proizvodnja ostvarena je na nivou od 25002.66±7755.39 kg mleka sa 3.61±0.01% mlečne masti. Bikovi-očevi krava, klasa HF gena i godina izlučenja imali su visoko značajan uticaj (p≤0.01), dok je uticaj razloga izlučenja bio značajan (p≤0.05) na trajanje života krava.