Analysis of longevity in Slovenian holstein cattle The longevity of Slovenian Holstein population was analysed using survival analysis with a Weibull proportional hazard model. Data spanned the period between January 1991 and January 2010 for 116,200 cows from 3,891 herds. Longevity was described as the length of productive life-from first calving till culling or censoring. Records above the sixth lactation were censored to partially avoid preferential treatment. Statistical model included the effect of age at first calving, stage of lactation within parity, yearly herd size deviation, season defined as year, herd, and sire-maternal grandsire (mgs). Some effects had time varying covariates, which lead to 1,839,307 or on average 16 elementary records per cow. Herd and sire-maternal grandsire effects were modelled hierarchically. Pedigree for sires and maternal grandsires included 2,284 entries. Estimated variance between herds was 0.12, while between sire variance was 0.04. Heritability was evaluated at 0.14. Genetic trend for sires was unfavourable, but not significant. A further research is needed to define the required number of daughters per sire and the dynamics of genetic evaluation for sires whose majority of daughters still have censored records.
The main part of Slovenian Simmental breed is selected for milk production. Genetic changes in a population should be checked in the case of selection on more traits at the same time. The estimation of genetic trend is the best tool to follow genetic changes in a population. In this paper we present the estimated genetic trends for traits with high economic weight in total selection of Slovenian Simmental breed. Results show that the greatest genetic progress was attained for milk production trait and conformation traits for udder. In other traits not so high genetic progress was attained. In the case of muscularity significant negative genetic progress was attained in the last 12 years.
The pedigree information of 3613 animals registered in the Slovenian Haflinger stud book from birth year 1905 to 2008 were analysed using PROC INBREED in SAS/ STAT with the purpose of analysis of inbreeding level in Slovenian Haflinger population. Relationship (R) analysis was restricted to possible mating partners that had offspring born between 2004 and 2008 (i.e., 323 mares and 58 stallions). An increasing trend of inbreeding coefficients (F) was observed in recent years, although a generally low F was detected. Mean values of R between possible mating partners were mostly around zero, while maximum values ranged up to 0.63. The development of application that would ease the calculations of F and R could help breeders to prevent related mating in the future
Selection pressure on protein content (PC), and thus milk composition changes have manifested as an increasingly narrow fat -protein ratio (FPR). In addition, higher somatic cell count (SCC) in milk has been observed in recent years, and that is why it is hypothesized that milk composition changes affect cow's immune response resulting in higher SCC. 2,459,250 test day (TD) records of 127,499 Slovenian Simmental (SIM) cows from years 2004 to 2017 were used for this study. For the estimation of (co)variance components two multiple trait animal TD models were used (M1, M2). M1 included SCC and FPR while M2 included SCC, fat content (FC) and PC. For comparisson of results parameters from the routine single-trait national genetic evaluation were used. Heritability estimates (h²) for SCC, FC and PC from M2 (0.34, 0.29, 0.38 respectively) were very similar to those form national evaluation; h² for FPR was lower than for the other traits (0.22). Both, estimated genetic correlation (r g =-0.1) and estimated phenotypic correlation (r p =-0.007) among SCC and FPR in M1 were negative and low. r p in M2 were positive, but low for all three trait pairs (0.062-0.076) and r g for SCC-PC was similar (0.069). Conversely, FC-PC r g (0.502) was positive and moderate whereas SCC-FC r g (-0.046) was negative and low. Results confirm the hypothesis by suggesting the possibillity of unpredicted and unwanted long-term cumulative effect of seemingly irrelevantly small genetic changes of individual trait.
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