Vpliv križanja na proizvodne lastnosti krav molznic v Sloveniji

Bric, Marija (author), Klopčič, Marija (mentor)

Cilj magistrskega dela je oceniti učinek križanja na proizvodne lastnosti čistopasemskih krav molznic lisaste in črno-bele pasme v primerjavi s križankami v Sloveniji. Številne študije poročajo o pozitivnih učinkih križanja različnih mlečnih pasem govedi na lastnosti prireje, zdravja, dolgoživosti ter ekonomiko reje krav molznic. V analizo smo vključili 382.829 standardnih laktacij od 157.339 krav črno-bele in lisaste pasme ter križank med omenjenima dvema pasmama, ki so telile v letih 2010 do 2018. Živali smo razdelili v pet pasemskih razredov glede na delež črno-bele pasme. V statistični model smo kot sistematske vplive vključili pasmo, zaporedno telitev, vpliva leta telitve ter meseca telitve smo ugnezdili znotraj pasme, naključni del modela pa je sestavljal vpliv dolžine laktacije. Ugotovili smo, da se je skupaj s povečevanjem deleža črno-bele pasme, povečevala tudi mlečnost živali ter prireja maščob (kg) in beljakovin (kg) v standardni laktaciji, zniževal pa se je delež maščob in beljakovin (%) v mleku. Mlečnost v standardni laktaciji je bila praviloma najnižja pri prvesnicah, najvišja pa pri kravah v tretji zaporedni laktaciji. Podobno velja za lastnosti količine prirejenih maščob in beljakovin v 305 dneh. Na količino prirejenega mleka, maščob in beljakovin je poleg pasme in zaporedne telitve statistično značilno vplivala tudi sezona telitve. Pri vseh pasemskih skupinah krav smo ugotovili tudi porast v količini prirejenega mleka v standardni laktaciji v tem obdobju. Fenotipske korelacije med posameznimi parametri prireje znotraj posameznih pasemskih razredov so bile statistično značilne (p<0,0001).

• Language: Slovenian
• Keywords: govedo, krave molznice, križanje, proizvodnja, lastnosti, Slovenija
• Work type: Master's thesis/paper
• Organization: BF - Biotechnical Faculty
• Year: 2021
• PID: 20.500.12556/RUL-124223
• COBISS.SI-ID: 46546179
• Publication date in RUL: 08.01.2021

Secondary language

• Language: English
• Title: Effect of crossbreeding on performance of dairy cows in Slovenia

Abstract

The aim of this thesis is to assess the effect of crossbreeding on performance of purebred Simmental and Holstein-Friesian dairy cows in comparison with crossbred dairy cows in Slovenia. Numerous different studies report about positive effects of crossbreeding different dairy cattle breeds on production traits, health, longevity and economy of dairy cattle breeding. The analysis included 382.829 standard lactations from 157.339 Holstein-Friesian, Simmental and crossbred cows between the mentioned two breeds, which calved in the years from 2010 to 2018. All animals were divided into five different classes, according to percentage of Holstein-Friesian breed. The impacts of breed, parity, year and season of calving represent the systematic part and the impact of duration of lactation represent the random part of the statistic model. We found out that increasing the proportion of Holstein-Friesian breed also increased milk, fat and protein yield in standard lactation, but decreases the content of fat and protein in milk. Cows in the first standard lactation had the lowest, and cows in the third standard lactation had the highest milk, fat and protein yield in 305 days. The impact of season of calving had a statistically significant effect on milk, fat and protein yield, beside the impacts of breed and parity. By all breed groups, we found an increasing of milk yield in standard lactation through the investigated period. The phenotypic correlations between milk, fat and protein yield within separate breed groups, were statistically significant (p<0.0001).

• Keywords: cattle, dairy cows, crossbreeding, production, traits, Slovenia