Variability and heritability of type traits of Holstein-Friesian bull dams

Abstract

Objective of this study was to calculate the variability and heritability of type traits in the nucleus herd of bull dams by using the linear method of evaluation, and to determine their importance in selection of cattle. Study included 127 Holstein-Friesian cows selected as bull dams on cattle farms of PKB Korporacija, Belgrade. By applying the Least square method, main variationstatistical parameters were calculated: arithmeitc mean, standard deviation, variation coefficient, standard error and variation range. Bull dams of Holstein- Friesian breed had average milk production of 10245.98 kg, with variation range from 6514 kg to 13251 kg. Average milk fat yield was 361.95 kg, and milk fat content 3,53%. Average values for type scores of Holstein-Friesian bull dams were: rump height 5.40, chest width 7.09, body depth 7.38, rump position 5.39, rump width 6.55, dairy form 7.35, rear legs set (rear view) 5.22, rear legs set (side view) 5.28, hoof angle 5.27, fore udder 6.65, front teats placement 5.43, teat length 4.76, udder depth 6.96, rear udder height 7.13, suspensory ligament 7.08 and rear teats placement 5.89. Also, heritability coefficients and errors were calculated for all milk and type traits. Type and body development scores are very important indicators of production ability of cows, their potential to consume sufficient quantities of food, produce high quality milk from the technological aspect, reduce the use of energy in production and remain as long as possible in exploitation.

Cilj ovih istraživanja bio je da se u nukleus zapatu bikovskih majki primenom linearnog metoda ocenjivanja krava izračuna varijabilnost i heritabilitet osobina tipa, i njihov značaj u selekciji goveda. Istraživanjem je obuhvaćeno 127 krava holštajn frizijske rase odabrane u kategoriju bikovskih majki na farmama PKB Korporacije, Beograd. Za sve ispitivane osobine primenom metoda najmanjih kvadrata izračunati su osnovni varijaciono-statistički parametri: aritmetička sredina, standardna devijacija, koeficijenti varijacije, standardna greška i interval varijacije. Bikovske majke holštajn frizijske rase ostvarile su prosečnu proizvodnju mleka od 10245.98 kg, pri čemu je interval variranja bio od 6514 kg do 13251 kg. Prosečna proizvodnja mlečne masti iznosila je 361,95 kg, a sadržaj mlečne masti 3,53%. Prosečne vrednosti ocene tipa bikovskih majki holštajn frizijske rase iznosile su: visina krsta 5,40, širina grudi 7,09, dubina tela 7,38, položaj karlice 5,39, širina karlice 6,55, mlečne karakteristike 7,35, položaj zadnjih nogu otpozadi 5,22, položaj zadnjih nogu sa strane 5,28, ugao papaka 5,27, prednja veza vimena 6,65, pozicija prednjih sisa 5,43, dužina sisa 4,76, dubina vimena 6,96, visina zadnjeg vimena 7,13, centralni ligament 7,08 i položaj zadnjih sisa 5,89. Osim toga za sve osobine mlečnosti i tipa izračunati su koeficijenti heritabiliteta i njihove greške. Ocene tipa i telesne razvijenosti su veoma važni pokazatelji proizvodnih sposobnosti krava, njihovih mogućnosti da konzumiraju dovoljne količine hrane, daju tehnološki kvalitetno mleko, smanje utrošak energije u proizvodnji i što duže ostanu u eksploataciji.