Povezava med plemensko vrednostjo krav za mlečnost in klavno kakovostjo sinov pri lisastem govedu

Vodopivc, Urban (author), Žgur, Silvester (mentor), Leskovec, Jakob (comentor)

Selekcija slovenske pasme lisasto govedo je v zadnjih 50. letih pretežno usmerjena v prirejo mleka. V nalogi smo analizirali korelacije med lastnostmi klavne kakovosti bikov, vključenih v progeni test, in napovedmi plemenskih vrednostmi (NPV) za lastnosti mlečnosti njihovih mater. Analizo smo opravili pri 1.952 bikih, ki so bili zaklani med letoma 1990 in 2020. Najmočnejšo korelacijo smo izračunali med NPV za količino mleka pri materah ter maso toplih polovic (r = 0,17). Z večanjem NPV za količino mleka mater je delež mesa v klavnih polovicah sinov upadal (r = -0,13), delež loja pa naraščal (r = 0,11). Delež večvrednih kosov (r = 0,15) in delež mesa v večvrednih kosih (r = 0,15) sinov pa sta z NPV za količino mleka pri materah naraščala. EUROP oceni za konformacijo in zamaščenost ter klavnost sinov niso bile statistično značilno korelirane z NPV za lastnosti mlečnosti pri materah, prav tako NPV za vsebnost maščob in beljakovin v mleku pri materah nista bili korelirani z nobeno od opazovanih lastnosti klavne kakovosti sinov. NPV za okvir mater je najmočneje korelirana s konformacijo sinov (r = -0,11), kar pomeni, da se je konformacija klavnih trupov sinov s povečevanjem NPV za okvir mater slabšala, medtem ko se je delež loja v trupih sinov, z večanjem okvirja pri materah povečal (r = 0,09). Korelacija podpira ugotovitev, da sta bili NPV lastnosti mlečnosti in okvirja negativno korelirani z deležem mesa v klavnih polovicah sinov (r = -0,13 in -0,15). Iz sklopa plodnosti se je za najpomembnejšo izkazala NPV za starost ob prvi telitvi, saj ta odraža sposobnost za rast sinov. Korelacija med NPV za starost mater ob prvi telitvi in maso toplih polovic sinov (r = 0,21) nakazuje, da sinovi dosegajo večje mase toplih polovic ob zakolu pri materah, ki prvič telijo mlajše. S povečanjem NPV za starost ob prvi telitvi, delež mesa v klavnih polovicah sinov upada (r = -0,22), delež loja pa narašča (r = 0,16). Korelacije med spremljanimi lastnostmi so osnova za nadaljnjo selekcijsko delo in ohranjanje kombiniranega tipa pri lisastem govedu.

• Language: Slovenian
• Keywords: govedo, krave, biki, progeni test, plemenska vrednost, klavna kakovost, korelacija, lisasto govedo
• Work type: Master's thesis/paper
• Organization: BF - Biotechnical Faculty
• Year: 2022
• PID: 20.500.12556/RUL-141680
• COBISS.SI-ID: 124739075
• Publication date in RUL: 05.10.2022

Secondary language

• Language: English
• Title: Correlation between breeding values for milk traits of simmental cows and carcass traits of their sons

Abstract

In the last 50 years, the selection of Simmental cattle in Slovenia has been mainly focused on milk production. In this master thesis we analyzed the correlations between carcass traits of bulls included in progeny testing, and estimated breeding values (EBV) for milk production traits of their dams. The analysis included 1.952 bulls slaughtered between 1990 and 2020. The strongest correlation we found was between the EBV for milk yield of dams and carcass warm weight (r = 0.17) of their sons. As the EBV for milk yield of the dams increased, the meat percentage in the carcasses of the sons decreased (r = -0.13), and fat percentage increased (r = 0.11). In contrast the proportion of higher-value carcass cuts (r = 0.15) and the proportion of meat in higher-value carcass cuts (r = 0.15) in sons increased with the EBV for milk yield of dams. EUROP conformation and fatness scores and dressing percentage of sons were not statistically significantly correlated with EBV for milk yield of dams, and EBV for milk fat and protein percent were also not correlated with carcass traits of sons. EBV for maternal frame size was most strongly correlated with their sons EUROP carcass conformation score (r = -0.11), indicating that the carcass conformation of sons deteriorated with increasing frame size of dams, whereas carcass fat percentage increased with increasing frame size (r = 0.09). This trend was supported by the finding that EBV for milk yield and frame size of dams was negatively correlated with carcass meat percentage in sons (r = -0.13 and -0.15, respectively). Among the group of EBV, related to fertility, EBV for age at first calving was found to be the most important as it reflects the growth potential of the cow. The correlation between EBV for age at first calving of dams and carcass weight of sons (r = 0.21) shows that sons of cows younger at first calving achieve higher carcass weights at slaughter. As EBV was increased for age at first calving of dams, the percentage of carcass meat in sons decreased (r = 0.22) and the percentage of carcass fat increased (r = 0.16). These calculated correlations between those observed traits are the basis for further selection work and maintenance of the dual purpose of Simmental breed.

• Keywords: cattle, cows, bulls, progeny testing, breeding value, carcass traits, correlation, Simmental breed