Estimation of Genetic Parameters and Breeding Values of Milk Traits for Simmental Cattle in Croatia Using a Lactation Animal Model

The objective of this study was to estimate genetic parameters and to predict breeding values for dairy traits in Simmental cattle in Croatia by developing an animal lactation model. Data consisted of 30761 first lactation records of cows born between 1985 and 2001. By including the pedigree there was a total of 48748 animals. The following effects were analyzed: age, season and year at first calving, days open, breeding organization, farm, animal, and genetic group. Adequacy of the models was tested by using F tests for fixed effects, and REML functions and ‘Mendelian sampling’ for the whole models. The best fit model was determined to have the following effects: age at first calving, days open, year x season interaction and breeding organization x year interaction as fixed, and animal and farm x year as random effects. By including genetic group the model was further improved. From this model, the following heritabilites were estimated: 0.34 ± 0.02, 0.30 ± 0.02, 0.29 ± 0.03 for milk, milk fat and protein yield, respectively. Further, phenotypic and genetic trends were analyzed. The genetic gain in milk traits has been low so far, but by using an appropriate animal model, the breeding value prediction is expected to be improved in terms of accuracy and precision

Estimation of Genetic Parameters and Breeding Values of Milk Traits for Simmental Cattle in Croatia Using a Lactation Animal Model

The objective of this study was to estimate genetic parameters and to predict breeding values for dairy traits in Simmental cattle in Croatia by developing an animal lactation model. Data consisted of 30761 first lactation records of cows born between 1985 and 2001. By including the pedigree there was a total of 48748 animals. The following effects were analyzed: age, season and year at first calving, days open, breeding organization, farm, animal, and genetic group. Adequacy of the models was tested by using F tests for fixed effects, and REML functions and ‘Mendelian sampling’ for the whole models. The best fit model was determined to have the following effects: age at first calving, days open, year x season interaction and breeding organization x year interaction as fixed, and animal and farm x year as random effects. By including genetic group the model was further improved. From this model, the following heritabilites were estimated: 0.34 ± 0.02, 0.30 ± 0.02, 0.29 ± 0.03 for milk, milk fat and protein yield, respectively. Further, phenotypic and genetic trends were analyzed. The genetic gain in milk traits has been low so far, but by using an appropriate animal model, the breeding value prediction is expected to be improved in terms of accuracy and precision

Genetski parametri za svojstva sperme i rasta mladih simentalskih bikova iz performance testa

The objective of this study was to estimate genetic and environmental variances and heritabilities for body measurements, daily gain, semen volume and semen concentration of young Simmental bulls. In addition, genetic trends for those traits were analyzed. Data utilized in this study consisted of records of 955 young Simmetal bulls born from 1974 to 1995 and were provided by the Performance Test Station - Varazdin. The test for growth traits started at the age of 120-d, and finished at 365-d. Generally, body measurements were taken every month, but there were animals with lost records. In order to smooth data and predict values at ages of 205- and 365-d, the spline analysis was applied. The following growth traits were derived: weights, heights at withers, hearth girth, and chest depth, predicted at 205- and 365-d of age, respectively. Further, average daily gain from 205- do 365-d was calculated. The semen collection started at approximately 11 months of age. The records included semen volume and concentration. Variance and covariance components and associated heritabilities were estimated by REML from a set of single-trait animal models. Fixed effects were defined as birth year and season, and animal effect was defined as random effect. The heritability estimates for growth traits ranged from .14 to .38. Heritability estimate for semen concentration was moderate (.26). Thus, the improvement of concentration, or at least not negative genetic trend, can be expected even if only phenotypic selection is practiced. This cannot be said for semen volume, as heritability estimate in the present study was low (.04). In this study no clear genetic trend for semen nor growth traits were detected.Cilj rada bio je procjena genetskih i okolišnih varijanci i heritabiliteta za tjelesne mjere, dnevni prirast, volumen i koncentracije sperme mladih simentalskih bikova. Osim toga procijenjeni su genetski trendovi za navedena svojstva. U radu su analizirani podaci iz performance testne stanice od 955 mladih bikova rođenih između 1974 i 1995 godine. Test za svojstva rasta započeo je u dobi od 120 dana, a završio s dobi od 365 dana. U pravilu bikovi su u testu mjereni svakih mjesec dana. Spline analizom procijenjene su tjelesne mjere u dobi od 205 i 365 dana, pri čemu su izvedeni slijedeći pokazatelji rasta: težina, visina grebena, opseg prsa i dubina prsa. Osim toga procijenjen je prosječni dnevni prirast od 205 do 365 dana. Polučivanje sjemena počelo je u dobi bikova od 11 mjeseci. Za svaki ejakulat izmjereni su volumen i koncentracija sjemena. Komponente varijance i kovarijance procijenjene su REML metodom koristeći animal model. Godina i sezona definirani su kao fiksni utjecaji, a utjecaj same životinje kao slučajan. Procijenjeni heritabiliteti za svojstva rasta kretali su se od .14 do .38. Za koncentraciju sjemena procjena je bila 0.26. Povećanje koncentracije ili u najmanju ruku ne negativni genetski trend može se očekivati čak i samom fenotipskom selekcijom. Međutim, zbog niskog heritabiliteta (.04) to isto se ne može očekivati za volumen sjemena. Ni za jedno od promatranih svojstva nije utvrđen jasan genetski trend

The influence of breed and lactation number on goats lactation curve parameters

Istraživanje utjecaja pasmine i redoslijeda laktacije na pojavu vrha proizvodnje mlijeka, na vrijeme pojave vrha proizvodnje mlijeka i na perzistenciju, provedeno je s istim alpina i sanskim kozama tijekom prvih pet laktacija. Mliječnost je kontrolirana jednom na mjesec. Rezultati mjesečnih kontrola mliječnosti korigirani su na 50., 100., 150. i 200. dan laktacije, pri čemu se koristila nelinearna funkcija. Korekcija količine mlijeka provedena je jednadžbom Wood-a (1967). Vrijednosti vrha proizvodnje, vrijeme pojave vrha i perzistencije određivani su primjenom izračunatih vrijednosti parametara toka laktacije a, b i c, prema jednadžbi Wooda. Izračunate vrijednosti za svaku pojedinu pasminu i laktaciju statistički su analizirane linearnim modelom (Harvey, 1975). Među pasminama nisu ustanovljene značajne razlike u vrhu proizvodnje mlijeka i perzistenciji, dok su značajne razlike u vremenu pojave vrha ustanovljene samo u I. laktaciji. Redoslijed laktacije značajno je utjecao na vrijeme pojave vrha i na perzistenciju. Vrh proizvodnje mlijeka značajno se povećao s porastom redoslijeda laktacije sve do IV. jarenja.Research relative to the influence of breed and number of lactation, on milk yields peak, time of reaching peak yield and persistency, was carried out using the same Alpina and Saanen goats through the first five lactations. Milk production was controlled once a month. The results were corrected on the 50th, 100th, 150th and 200th day of lactation using a non-linear function. Milk yield\u27s correction was done using Wood\u27s equation (1967). Milk peak yield values, time of reaching milk peak yield and persistency were determined using calculated lactation parameter values a, b and c according to the Wood equation. Each breed\u27s calculated value and lactation was statistically analyzed using linear model (Harvey, 1975). Differences between milk yield peak and persistency as well as between breeds were not significant. Significant were differences within time of reaching milk yield peak during the first lactation. Lactation number influenced significantly time of reaching milk peak and persistency. Milk yield\u27s peak increased significantly with increased number of lactation up to the fourth kidding

Genetski parametri za svojstva sperme i rasta mladih simentalskih bikova iz performance testa

The objective of this study was to estimate genetic and environmental variances and heritabilities for body measurements, daily gain, semen volume and semen concentration of young Simmental bulls. In addition, genetic trends for those traits were analyzed. Data utilized in this study consisted of records of 955 young Simmetal bulls born from 1974 to 1995 and were provided by the Performance Test Station - Varazdin. The test for growth traits started at the age of 120-d, and finished at 365-d. Generally, body measurements were taken every month, but there were animals with lost records. In order to smooth data and predict values at ages of 205- and 365-d, the spline analysis was applied. The following growth traits were derived: weights, heights at withers, hearth girth, and chest depth, predicted at 205- and 365-d of age, respectively. Further, average daily gain from 205- do 365-d was calculated. The semen collection started at approximately 11 months of age. The records included semen volume and concentration. Variance and covariance components and associated heritabilities were estimated by REML from a set of single-trait animal models. Fixed effects were defined as birth year and season, and animal effect was defined as random effect. The heritability estimates for growth traits ranged from .14 to .38. Heritability estimate for semen concentration was moderate (.26). Thus, the improvement of concentration, or at least not negative genetic trend, can be expected even if only phenotypic selection is practiced. This cannot be said for semen volume, as heritability estimate in the present study was low (.04). In this study no clear genetic trend for semen nor growth traits were detected.Cilj rada bio je procjena genetskih i okolišnih varijanci i heritabiliteta za tjelesne mjere, dnevni prirast, volumen i koncentracije sperme mladih simentalskih bikova. Osim toga procijenjeni su genetski trendovi za navedena svojstva. U radu su analizirani podaci iz performance testne stanice od 955 mladih bikova rođenih između 1974 i 1995 godine. Test za svojstva rasta započeo je u dobi od 120 dana, a završio s dobi od 365 dana. U pravilu bikovi su u testu mjereni svakih mjesec dana. Spline analizom procijenjene su tjelesne mjere u dobi od 205 i 365 dana, pri čemu su izvedeni slijedeći pokazatelji rasta: težina, visina grebena, opseg prsa i dubina prsa. Osim toga procijenjen je prosječni dnevni prirast od 205 do 365 dana. Polučivanje sjemena počelo je u dobi bikova od 11 mjeseci. Za svaki ejakulat izmjereni su volumen i koncentracija sjemena. Komponente varijance i kovarijance procijenjene su REML metodom koristeći animal model. Godina i sezona definirani su kao fiksni utjecaji, a utjecaj same životinje kao slučajan. Procijenjeni heritabiliteti za svojstva rasta kretali su se od .14 do .38. Za koncentraciju sjemena procjena je bila 0.26. Povećanje koncentracije ili u najmanju ruku ne negativni genetski trend može se očekivati čak i samom fenotipskom selekcijom. Međutim, zbog niskog heritabiliteta (.04) to isto se ne može očekivati za volumen sjemena. Ni za jedno od promatranih svojstva nije utvrđen jasan genetski trend