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 (h.sup.2) for SCC, FC and PC from M2 (0.34, 0.29, 0.38 respectively) were very similar to those form national evaluation; h.sup.2 for FPR was lower than for the other traits (0.22). Both, estimated genetic correlation (r.sub.g=-0.1) and estimated phenotypic correlation (r.sub.p=-0.007) among SCC and FPR in M1 were negative and low. r.sub.p in M2 were positive, but low for all three trait pairs (0.062-0.076) and r.sub.g for SCC-PC was similar (0.069). Conversely, FC-PC r.sub.g (0.502) was positive and moderate whereas SCC-FC r.sub.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.
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.
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.
Za analizo dolgoživosti smo pri slovenski črno-beli populaciji govedi uporabili metodologijo analize preživetja in Weibullov model sorazmernih ogroženosti. V analizo smo vključili podatke 116.200 krav iz 3.891 čred skozi obdobje od januarja 1991 do januarja 2010. Dolgoživost je bila predstavljena kot doba produktivnega življenja, ki je definirana kot število od prve telitve do izločitve ali do datuma zajema podatkov za živali, ki so na ta datum bile še žive. Šesto in kasnejše laktacije smo okrnili na konec šeste laktacije, da smo omilili precenjenost boljših živali. V statistični model smo vključili vpliv starosti ob prvi telitvi, stadija laktacije ločeno za vsako zaporedno laktacijo, spreminjanje velikosti črede med leti, leto telitve, čredo, očeta in materinega očeta. Ravni nekaterih vplivov so časovno spremenljivi, kar povzroči, da smo v analizi obravnavali 1.839.307 zapisov ali povprečno 16 osnovnih zapisov na kravo. Čreda in vpliv očeta z materinim očetom sta bila v model vključena hierarhično. Rodovnik za očete in materine očete je obsegal 2.284 zapisov. Ocenjena varianca za vpliv črede je znašala 0,12, medtem ko je ocena variance med očeti znašala 0,04. Dednostni delež je bil ocenjen na 0,14. Genetski trend ima negativno smer, a ni statistično značilen. Potrebne bodo nadaljnje raziskave, da bomo določili zadostno število hčera po biku in dinamiko obračunov plemenskih vrednosti za bike, ki imajo večino hčera še v fazi prireje.
Analysis of inbreeding and inbreeding depression was done on the data of routine breeding value estimation for milk production data on Holstein population in Slovenia. A pedigree file of 106 433 ...animals born from 1952 to 2005 was investigated for the occurrence of inbreeding. The maximum inbreeding was 37.5. However average inbreeding coefficients of inbred cows (1.3 %) and of all cows with test day records (0.989 %) were low. Daily milk, protein, and fat yield of first five lactation for 86 122 cows were analyzed. Inbreeding was included in the animal model as a linear covariate. The regression coefficients of milk, fat, and protein yield, multiplied with 305 days present inbreeding depression of lactation yields, were -22.17 kg, -0.601 kg and -0.387 kg respectively, for 1 % of inbreeding.
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