Influence of environmental and genetical factors on urea content in milk with Holstein breed cows

Ciljevi ovoga rada su bili utvrditi u kojoj mjeri okolišni čimbenici (redoslijed i stadij laktacije, starost kod prvog teljenja, sezona teljenja, regija i stado) imaju utjecaj na sadržaj ureje u mlijeku, te povezanost sadržaja ureje u mlijeku sa ostalim svojstvima mliječnosti krava. Najveća razina sadržaja ureje u mlijeku je zabilježena u prvoj laktaciji, u razdoblju između 110 i 140 dana, kada se kretala oko 23,6 mg/100ml. Na kraju prve laktacije prosječni sadržaj ureje u mlijeku je iznosio oko 21,6 mg/100ml. Drugu laktaciju karakterizira nešto veći sadržaj ureje, u razdoblju odmah nakon teljenja kada su zabilježene najviše vrijednosti od svih praćenih laktacija. Starost krava kod prvog teljenja je također imao utjecaj na sadržaj ureje u mlijeku. Krava koje su telile u dobi od 24. do 26. mjeseca imale su najvišu vrijednost sadržaja ureje koji je za navedeno razdoblje iznosio 23,2 mg/100ml. Najniža vrijednost sadržaja ureje je zabilježena kod krava koje su telile u dobi od 18. mjeseci i iznosila je ispod 20 mg/100ml. I sezona teljenja je utjecala na sadržaj ureje u mlijeku. U zimskoj sezoni 2004. godine zabilježene su najmanje vrijednosti sadržaja ureje u mlijeku, dok je u jesenskoj sezoni iste godine izmjeren najviši sadržaj ureje u mlijeku (24 mg/100ml). U narednim sezonama teljenja dolazi do opadanja sadržaja ureje u mlijeku. Razlike u sadržaju ureje u mlijeku utvrđene su između županija. Najviša vrijednost heritabiliteta (0,08) ocjenjena je modelom gdje je kao usporediva grupa korištena interakcija između stada i kontrolnog dana. U istraživanju, udio varijabilnosti pojašnjen interakcijom stado-dan kontrole, je iznosio 67%, dok je 25% varijabilnosti sadržaja ureje ostalo neprotumačeno. Ovaj je model korišten i pri procjeni uzgojne vrijednosti. Također je testiran i model gdje je utjecaj stada korišten kao usporediva grupa, te je ovim modelom ocijenjena najniža vrijednost heritabiliteta (0,03). U modelima gdje je interakcija između stada i godina testiranja korištena kao usporediva grupa ocjenjene su više vrijednosti heritabiliteta (0,04 i 0,05) u odnosu na prethodni model. Izračunate fenotipske korelacije između sadržaja ureje i osobina mliječnosti: dnevna količina mlijeka, dnevna količina i sadržaj masti i bjelančevina su bile statistički značajne (P <0,0001). Pozitivna i niska fenotipska korelacija (0,15) utvrđena je između sadržaja ureje i dnevne količine mlijeka, između sadržaja ureje i dnevne količine masti (0,10), te između sadržaja ureje i količine bjelančevina (0,16). Između sadržaja ureje i sadržaja mliječne masti koeficijent korelacije je bio nizak i negativan (-0,05) dok je između sadržaja ureje i sadržaja bjelančevina on bio nizak i pozitivan (-0,03).The aims of this paper were to determine to which extent the environmental factors (order and stadium of lactation, age with the first calving, calving season, region and herd) have the influence on the content of urea in milk, and connection of urea content in milk with other features of milk production with cows. The largest share of urea content in milk was recorded in the first lactation, in the period between 110 and 140 days, when it was around 23.6 mg/100ml. In the end of the first lactation the average urea content in milk was around 21.6 mg/100ml. The second lactation is characterized by somewhat bigger urea content, in the period immediately after calving when the highest values from all tracked lactations was recorded. The age of cows with their first calving also had an impact on urea content in milk. Cows that calved in the age from 24th to 26th month had the highest value of urea content, which was 23.2 mg/100ml for the stated period. The lowest value of urea content was recorded with cows that calved in the age of 18 months and it was below 20 mg/100ml. Season of calving also influenced the urea content in milk. In winter season 2004 the lowest values of urea content in milk were recorded, while in the autumn season of the same year the highest urea content in milk was measured (24 mg/100ml). In the following calving season increase of urea content in milk followed. The differences in urea content in milk were determined between the counties. The highest value of heritability (0.08) was estimated by the model where as a comparisson group the interaction between the herds and control day was used. In a research the share of variability was explained by the interaction herd-control day and it was 67%, while 25% of variability of urea content in milk remained unexplained. This model was used when estimating the breeding values. A model was also tested where the influence of herd was used as a comparisson group and by this model the lowest value of heritability was estimated (0.03). In models where interaction between the herd and years of testing was used as comparisson group higher values of heritability (0.04 and 0.05) were measured with respect to the previous model. Calculated phenotypical correlations between the urea content and milk production features: daily amount of milk, daily amount and content of fats and proteins were statistically significant (P <0.0001). Positive and low phenotypical correlation (0.15) was determined between the content of urea and daily amount of milk, between the urea content and daily amount of fat (0.10), and between urea content and amount of proteins (0.16). Between the urea content and content of milk fat the coefficient of correlations was low and negative (-0.05),while between the urea content and content of proteins it was low and positive (-0.03)

INFLUENCE OF ENVIRONMENTAL AND GENETICAL FACTORS ON UREA CONTENT IN HOLSTEIN BREED COWS MILK

Ciljevi ovoga rada bili su utvrditi u kojoj mjeri oko¬lišni čimbenici (redosljed i stadij laktacije, starost kod prvoga teljenja, sezona teljenja, regija i stado) imaju utjecaj na sadržaj ureje u mlijeku te povezanost sadržaja ureje u mlijeku s ostalim svojstvima mliječnosti krava. Najveća razina sadržaja ureje u mlijeku zabilježena je u prvoj laktaciji, u razdoblju između 110 i 140 dana, kada se kretala oko 23,6 mg/100 ml. Na kraju prve laktacije prosječni sadržaj ureje u mlijeku iznosio je oko 21,6 mg/100 ml. Drugu laktaciju karakterizira nešto veći sadržaj ureje, u razdoblju odmah nakon teljenja, kada su zabilježene najviše vrijednosti od svih praćenih laktacija. Starost krava kod prvoga teljenja također je imala utjecaj na sadržaj ureje u mlijeku. Krave koje su telile u dobi 24.¬26. mjeseca imale su najvišu vrijednost sadržaja ureje, koji je za navedeno razdoblje iznosio 23,2 mg/100ml. Najniža vrijednost sadržaja ureje zabilježena je kod krava koje su telile u dobi 18 mjeseci i iznosila je ispod 20 mg/100 ml. I sezona teljenja utjecala je na sadržaj ureje u mlijeku. U zimskoj sezoni 2004. godine zabilježene su najmanje vrijednosti sadržaja ureje u mlijeku, dok je u jesenskoj sezoni iste godine izmjeren najviši sadržaj ureje u mlijeku (24 mg/100 ml). U narednim sezonama teljenja dolazi do opadanja sadržaja ureje u mlijeku. Razlike u sadržaju ureje u mlijeku utvrđene su između županija. Najviša vrijednost heritabiliteta (0,08) ocijenje¬na je modelom gdje je kao usporediva grupa korištena interakcija između stada i kontrolnoga dana. U istraživa¬nju, udio varijabilnosti pojašnjen interakcijom stado-dan kontrole, iznosio je 67%, dok je 25% varijabilnosti sadrža¬ja ureje ostalo neprotumačeno. Taj je model korišten i pri procjeni uzgojne vrijednosti. Također je testiran i model gdje je utjecaj stada korišten kao usporediva grupa te je njime ocijenjena najniža vrijednost heritabiliteta (0,03). U modelima gdje je interakcija između stada i godina testiranja korištena kao usporediva grupa, ocijenjene su više vrijednosti heritabiliteta (0,04 i 0,05) u odnosu na prethodni model. Izračunate fenotipske korelacije izme¬đu sadržaja ureje i osobina mliječnosti: dnevna količina mlijeka, dnevna količina i sadržaj masti i bjelančevina bile su statistički značajne (P<0,0001). Pozitivna i niska fenotipska korelacija (0,15) utvrđena je između sadržaja ureje i dnevne količine mlijeka, između sadržaja ureje i dnevne količine masti (0,10) te između sadržaja ureje i količine bjelančevina (0,16). Između sadržaja ureje i sadržaja mliječne masti koeficijent korelacije bio je nizak i negativan (-0,05), dok je između sadržaja ureje i sadr¬žaja bjelančevina bio nizak i pozitivan (-0,03).The aims of this paper were to determine to which extent the environmental factors (order and stadium of lactation, age with the first calving, calving season, region and herd) have the influence on the content of urea in milk, and connection of urea content in milk with other features of milk production with cows. The largest share of urea content in milk was recorded in the first lactation, in the period between 110 and 140 days, when it was around 23.6 mg/100 ml. In the end of the first lactation the average urea content in milk was around 21.6 mg/100 ml. The second lactation is chara¬cterized by somewhat bigger urea content, in the period immediately after calving when the highest values from all tracked lactations was recorded. The age of cows with their first calving also had an impact on urea con¬tent in milk. Cows that calved in the age from 24th to 26th month had the highest value of urea content, being 23.2 mg/100 ml for the stated period. The lowest value of urea content was recorded with cows that calved in the age of 18 months and it was below 20 mg/100 ml. Season of calving also influenced the urea content in milk. In winter season 2004 the lowest values of urea content in milk were recorded while in the autumn sea¬son of the same year the highest urea content in milk was measured (24 mg/100 ml). In the following calving season increase of urea content in milk followed. The differences in urea content in milk were determined between the counties. The highest value of heritabi-lity (0.08) was estimated by the model where, as a comparison group, the interaction between the herds and control day was used. In the research the share of variability was explained by the interaction herd-control day and it was 67%, while 25% of variability of urea con¬tent in milk remained unexplained. This model was used when estimating the breeding values. A model was also tested where the influence of herd was used as a comparison group, and by this model the lowest value of heritability was estimated (0.03). In models where interaction between the herd and years of testing was used as comparison group, higher values of heritability (0.04 and 0.05) were measured with respect to the previous model. Calculated phenotypical correlations between the urea content and milk production features: daily amount of milk, daily amount and content of fats and proteins were statistically significant (P <0.0001). Positive and low phenotypical correlation (0.15) was determined between the content of urea and daily amo¬unt of milk, between the urea content and daily amount of fat (0.10), and between urea content and amount of proteins (0.16). The coefficient of correlations was low and negative (-0.05) between the urea content and content of milk fat, while between the urea content and content of proteins it was low and positive (-0.03)

OPPORTUNITIES AND DIFFICULTIES WITH THE PRODUCTION OF ENERGY FROM BIOGAS IN BOSNIA AND HERZEGOVINA

Danas kad se svijet suočava sa sve većim potrebama u energiji, a kao posljedica toga sa sve većom eksploatacijom prirodnih resursa, problemom zagađivanja okoliša i globalnim zatopljavanjem, pitanje pronalaženja i korištenja alternativnih, čistijih izvora energije nameće se samo po sebi. Današnja svjetska populacija koja broji oko 7 milijardi stanovnika, godišnje troši energije u iznosu oko 10,2 Gtoe. (Gtoe je ekvivalentno milijardi tona nafte). Ovo se odnosi na ukupnu primarnu energiju. Od ovog iznosa na električnu energiju otpada oko 15 500 TWh ili oko 18%, s tendencijom daljnjeg rasta, tako da su predviđanja da bi 2030. godine udio potrošnje električne energije iznosio oko 22% ukupne primarne svjetske potrošnje. S druge strane problem odlaganja otpada s farmi postaje sve veći, a pogotovo s povećanjem proizvodnje mesa i mlijeka. Jačanjem proizvodnih objekata raste i povećanje proizvodnje, a potreba za energijom je sve veća. U Bosni i Hercegovini postoje mogućnosti za proizvodnju bioplina na farmama i njegovo korištenje za proizvodnju energije, koja bi se koristila za osobne potrebe ili prodavala na tržištu energije. Problemi s proizvodnjom energije iz bioplina su nepostojanje zakonske regulative i niske cijene otkupa energije dobijene iz obnovljivih izvora.Today when the world faces growing energy needs, and conse-quently with the increasing exploitation of natural resources, environmental pollution problems and global warming, the issue of finding and using alternative, cleaner sources of energy is self-imposed. Today’s world population, which numbers about 7 billion people, spends energy of approximately 10.2 Gtoe. (Gtoe is a billion tons of oil equivalents). This refers to the total primary energy. Of this amount electricity accounts for about 15 500 TWh, or about 18%, with a tendency of further growth, so that the prediction is that in 2030 the share of electricity consumption will amount to about 22% of total primary energy consumed globally. On the other hand the problem of waste disposal from farms is growing, especially with the increasing production of meat and milk. With growing production facilities and higher production of milk the demands for energy are bigger. In Bosnia and Herzegovina, there are opportunities for biogas production onfarms and its use for energy production for personal needs or to be sold on the market. Problems with production of energy from biogas are the absence of statutory legislation and low cost of purchase of energy from renewable sources

Pokretanje biogasnih postrojenja na govedarskim farmama u Bosni i Hercegovini

U današnje vrijeme energija predstavlja bogastvo, a ujedno zauzima veliku ulogu u troškovim govedarske proizvodnje. U smanjenju postojećih resursa, bitno je okre¬nuti se traženju obnovljivh izvora energije. S druge strane povećanje broja grla na farma-ma dovodi do problema sa njegovi pravilnim skladištenjem i manupulacijom. Pred na-ma je usvajanje odgovarjućih direktiva EU koje regulišu ovu oblast, što će dovesti do još više problema za poljoprivredne proizvođače. Jačanjem proizvodnih objekata raste i povećanjem proizvodnje potreba za energijom je sve veća. Kod nas postoje mogućnosti za proizvodnju biogasa na  govedarskim farmama i korištenje istog za proizvodnju ene¬rgije. Ta energija bi se koristila za potrebe farmera ili prodavala na tržištu energije.Tre¬nutni problem za masovnu proizvodnjom energije iz biogasa je nepostojanje jasne za¬konske regulative i niske cijene otkupa energije dobijene iz obnovljivih izvora

With food to health : proceedings of the 10th International scientific and professional conference

Proceedings contains 13 original scientific papers, 10 professional papers and 2 review papers which were presented at "10th International Scientific and Professional Conference WITH FOOD TO HEALTH", organised in following sections: Nutrition, Dietetics and diet therapy, Functional food and food supplemnents, Food safety, Food analysis, Production of safe food and food with added nutritional value

Influence of environmental and genetical factors on urea content in milk with Holstein breed cows

Ciljevi ovoga rada su bili utvrditi u kojoj mjeri okolišni čimbenici (redoslijed i stadij laktacije, starost kod prvog teljenja, sezona teljenja, regija i stado) imaju utjecaj na sadržaj ureje u mlijeku, te povezanost sadržaja ureje u mlijeku sa ostalim svojstvima mliječnosti krava. Najveća razina sadržaja ureje u mlijeku je zabilježena u prvoj laktaciji, u razdoblju između 110 i 140 dana, kada se kretala oko 23,6 mg/100ml. Na kraju prve laktacije prosječni sadržaj ureje u mlijeku je iznosio oko 21,6 mg/100ml. Drugu laktaciju karakterizira nešto veći sadržaj ureje, u razdoblju odmah nakon teljenja kada su zabilježene najviše vrijednosti od svih praćenih laktacija. Starost krava kod prvog teljenja je također imao utjecaj na sadržaj ureje u mlijeku. Krava koje su telile u dobi od 24. do 26. mjeseca imale su najvišu vrijednost sadržaja ureje koji je za navedeno razdoblje iznosio 23,2 mg/100ml. Najniža vrijednost sadržaja ureje je zabilježena kod krava koje su telile u dobi od 18. mjeseci i iznosila je ispod 20 mg/100ml. I sezona teljenja je utjecala na sadržaj ureje u mlijeku. U zimskoj sezoni 2004. godine zabilježene su najmanje vrijednosti sadržaja ureje u mlijeku, dok je u jesenskoj sezoni iste godine izmjeren najviši sadržaj ureje u mlijeku (24 mg/100ml). U narednim sezonama teljenja dolazi do opadanja sadržaja ureje u mlijeku. Razlike u sadržaju ureje u mlijeku utvrđene su između županija. Najviša vrijednost heritabiliteta (0,08) ocjenjena je modelom gdje je kao usporediva grupa korištena interakcija između stada i kontrolnog dana. U istraživanju, udio varijabilnosti pojašnjen interakcijom stado-dan kontrole, je iznosio 67%, dok je 25% varijabilnosti sadržaja ureje ostalo neprotumačeno. Ovaj je model korišten i pri procjeni uzgojne vrijednosti. Također je testiran i model gdje je utjecaj stada korišten kao usporediva grupa, te je ovim modelom ocijenjena najniža vrijednost heritabiliteta (0,03). U modelima gdje je interakcija između stada i godina testiranja korištena kao usporediva grupa ocjenjene su više vrijednosti heritabiliteta (0,04 i 0,05) u odnosu na prethodni model. Izračunate fenotipske korelacije između sadržaja ureje i osobina mliječnosti: dnevna količina mlijeka, dnevna količina i sadržaj masti i bjelančevina su bile statistički značajne (P <0,0001). Pozitivna i niska fenotipska korelacija (0,15) utvrđena je između sadržaja ureje i dnevne količine mlijeka, između sadržaja ureje i dnevne količine masti (0,10), te između sadržaja ureje i količine bjelančevina (0,16). Između sadržaja ureje i sadržaja mliječne masti koeficijent korelacije je bio nizak i negativan (-0,05) dok je između sadržaja ureje i sadržaja bjelančevina on bio nizak i pozitivan (-0,03).The aims of this paper were to determine to which extent the environmental factors (order and stadium of lactation, age with the first calving, calving season, region and herd) have the influence on the content of urea in milk, and connection of urea content in milk with other features of milk production with cows. The largest share of urea content in milk was recorded in the first lactation, in the period between 110 and 140 days, when it was around 23.6 mg/100ml. In the end of the first lactation the average urea content in milk was around 21.6 mg/100ml. The second lactation is characterized by somewhat bigger urea content, in the period immediately after calving when the highest values from all tracked lactations was recorded. The age of cows with their first calving also had an impact on urea content in milk. Cows that calved in the age from 24th to 26th month had the highest value of urea content, which was 23.2 mg/100ml for the stated period. The lowest value of urea content was recorded with cows that calved in the age of 18 months and it was below 20 mg/100ml. Season of calving also influenced the urea content in milk. In winter season 2004 the lowest values of urea content in milk were recorded, while in the autumn season of the same year the highest urea content in milk was measured (24 mg/100ml). In the following calving season increase of urea content in milk followed. The differences in urea content in milk were determined between the counties. The highest value of heritability (0.08) was estimated by the model where as a comparisson group the interaction between the herds and control day was used. In a research the share of variability was explained by the interaction herd-control day and it was 67%, while 25% of variability of urea content in milk remained unexplained. This model was used when estimating the breeding values. A model was also tested where the influence of herd was used as a comparisson group and by this model the lowest value of heritability was estimated (0.03). In models where interaction between the herd and years of testing was used as comparisson group higher values of heritability (0.04 and 0.05) were measured with respect to the previous model. Calculated phenotypical correlations between the urea content and milk production features: daily amount of milk, daily amount and content of fats and proteins were statistically significant (P <0.0001). Positive and low phenotypical correlation (0.15) was determined between the content of urea and daily amount of milk, between the urea content and daily amount of fat (0.10), and between urea content and amount of proteins (0.16). Between the urea content and content of milk fat the coefficient of correlations was low and negative (-0.05),while between the urea content and content of proteins it was low and positive (-0.03)

INFLUENCE OF ENVIRONMENTAL AND GENETICAL FACTORS ON UREA CONTENT IN HOLSTEIN BREED COWS MILK

The aims of this paper were to determine to which extent the environmental factors (order and stadium of lactation, age with the first calving, calving season, region and herd) have the influence on the content of urea in milk, and connection of urea content in milk with other features of milk production with cows. The largest share of urea content in milk was recorded in the first lactation, in the period between 110 and 140 days, when it was around 23.6 mg/100 ml. In the end of the first lactation the average urea content in milk was around 21.6 mg/100 ml. The second lactation is chara¬cterized by somewhat bigger urea content, in the period immediately after calving when the highest values from all tracked lactations was recorded. The age of cows with their first calving also had an impact on urea con¬tent in milk. Cows that calved in the age from 24th to 26th month had the highest value of urea content, being 23.2 mg/100 ml for the stated period. The lowest value of urea content was recorded with cows that calved in the age of 18 months and it was below 20 mg/100 ml. Season of calving also influenced the urea content in milk. In winter season 2004 the lowest values of urea content in milk were recorded while in the autumn sea¬son of the same year the highest urea content in milk was measured (24 mg/100 ml). In the following calving season increase of urea content in milk followed. The differences in urea content in milk were determined between the counties. The highest value of heritabi-lity (0.08) was estimated by the model where, as a comparison group, the interaction between the herds and control day was used. In the research the share of variability was explained by the interaction herd-control day and it was 67%, while 25% of variability of urea con¬tent in milk remained unexplained. This model was used when estimating the breeding values. A model was also tested where the influence of herd was used as a comparison group, and by this model the lowest value of heritability was estimated (0.03). In models where interaction between the herd and years of testing was used as comparison group, higher values of heritability (0.04 and 0.05) were measured with respect to the previous model. Calculated phenotypical correlations between the urea content and milk production features: daily amount of milk, daily amount and content of fats and proteins were statistically significant (P <0.0001). Positive and low phenotypical correlation (0.15) was determined between the content of urea and daily amo¬unt of milk, between the urea content and daily amount of fat (0.10), and between urea content and amount of proteins (0.16). The coefficient of correlations was low and negative (-0.05) between the urea content and content of milk fat, while between the urea content and content of proteins it was low and positive (-0.03)

Influence of environmental and genetical factors on urea content in milk with Holstein breed cows

Ciljevi ovoga rada su bili utvrditi u kojoj mjeri okolišni čimbenici (redoslijed i stadij laktacije, starost kod prvog teljenja, sezona teljenja, regija i stado) imaju utjecaj na sadržaj ureje u mlijeku, te povezanost sadržaja ureje u mlijeku sa ostalim svojstvima mliječnosti krava. Najveća razina sadržaja ureje u mlijeku je zabilježena u prvoj laktaciji, u razdoblju između 110 i 140 dana, kada se kretala oko 23,6 mg/100ml. Na kraju prve laktacije prosječni sadržaj ureje u mlijeku je iznosio oko 21,6 mg/100ml. Drugu laktaciju karakterizira nešto veći sadržaj ureje, u razdoblju odmah nakon teljenja kada su zabilježene najviše vrijednosti od svih praćenih laktacija. Starost krava kod prvog teljenja je također imao utjecaj na sadržaj ureje u mlijeku. Krava koje su telile u dobi od 24. do 26. mjeseca imale su najvišu vrijednost sadržaja ureje koji je za navedeno razdoblje iznosio 23,2 mg/100ml. Najniža vrijednost sadržaja ureje je zabilježena kod krava koje su telile u dobi od 18. mjeseci i iznosila je ispod 20 mg/100ml. I sezona teljenja je utjecala na sadržaj ureje u mlijeku. U zimskoj sezoni 2004. godine zabilježene su najmanje vrijednosti sadržaja ureje u mlijeku, dok je u jesenskoj sezoni iste godine izmjeren najviši sadržaj ureje u mlijeku (24 mg/100ml). U narednim sezonama teljenja dolazi do opadanja sadržaja ureje u mlijeku. Razlike u sadržaju ureje u mlijeku utvrđene su između županija. Najviša vrijednost heritabiliteta (0,08) ocjenjena je modelom gdje je kao usporediva grupa korištena interakcija između stada i kontrolnog dana. U istraživanju, udio varijabilnosti pojašnjen interakcijom stado-dan kontrole, je iznosio 67%, dok je 25% varijabilnosti sadržaja ureje ostalo neprotumačeno. Ovaj je model korišten i pri procjeni uzgojne vrijednosti. Također je testiran i model gdje je utjecaj stada korišten kao usporediva grupa, te je ovim modelom ocijenjena najniža vrijednost heritabiliteta (0,03). U modelima gdje je interakcija između stada i godina testiranja korištena kao usporediva grupa ocjenjene su više vrijednosti heritabiliteta (0,04 i 0,05) u odnosu na prethodni model. Izračunate fenotipske korelacije između sadržaja ureje i osobina mliječnosti: dnevna količina mlijeka, dnevna količina i sadržaj masti i bjelančevina su bile statistički značajne (P <0,0001). Pozitivna i niska fenotipska korelacija (0,15) utvrđena je između sadržaja ureje i dnevne količine mlijeka, između sadržaja ureje i dnevne količine masti (0,10), te između sadržaja ureje i količine bjelančevina (0,16). Između sadržaja ureje i sadržaja mliječne masti koeficijent korelacije je bio nizak i negativan (-0,05) dok je između sadržaja ureje i sadržaja bjelančevina on bio nizak i pozitivan (-0,03).The aims of this paper were to determine to which extent the environmental factors (order and stadium of lactation, age with the first calving, calving season, region and herd) have the influence on the content of urea in milk, and connection of urea content in milk with other features of milk production with cows. The largest share of urea content in milk was recorded in the first lactation, in the period between 110 and 140 days, when it was around 23.6 mg/100ml. In the end of the first lactation the average urea content in milk was around 21.6 mg/100ml. The second lactation is characterized by somewhat bigger urea content, in the period immediately after calving when the highest values from all tracked lactations was recorded. The age of cows with their first calving also had an impact on urea content in milk. Cows that calved in the age from 24th to 26th month had the highest value of urea content, which was 23.2 mg/100ml for the stated period. The lowest value of urea content was recorded with cows that calved in the age of 18 months and it was below 20 mg/100ml. Season of calving also influenced the urea content in milk. In winter season 2004 the lowest values of urea content in milk were recorded, while in the autumn season of the same year the highest urea content in milk was measured (24 mg/100ml). In the following calving season increase of urea content in milk followed. The differences in urea content in milk were determined between the counties. The highest value of heritability (0.08) was estimated by the model where as a comparisson group the interaction between the herds and control day was used. In a research the share of variability was explained by the interaction herd-control day and it was 67%, while 25% of variability of urea content in milk remained unexplained. This model was used when estimating the breeding values. A model was also tested where the influence of herd was used as a comparisson group and by this model the lowest value of heritability was estimated (0.03). In models where interaction between the herd and years of testing was used as comparisson group higher values of heritability (0.04 and 0.05) were measured with respect to the previous model. Calculated phenotypical correlations between the urea content and milk production features: daily amount of milk, daily amount and content of fats and proteins were statistically significant (P <0.0001). Positive and low phenotypical correlation (0.15) was determined between the content of urea and daily amount of milk, between the urea content and daily amount of fat (0.10), and between urea content and amount of proteins (0.16). Between the urea content and content of milk fat the coefficient of correlations was low and negative (-0.05),while between the urea content and content of proteins it was low and positive (-0.03)

Influence of environmental and genetical factors on urea content in milk with Holstein breed cows

Ciljevi ovoga rada su bili utvrditi u kojoj mjeri okolišni čimbenici (redoslijed i stadij laktacije, starost kod prvog teljenja, sezona teljenja, regija i stado) imaju utjecaj na sadržaj ureje u mlijeku, te povezanost sadržaja ureje u mlijeku sa ostalim svojstvima mliječnosti krava. Najveća razina sadržaja ureje u mlijeku je zabilježena u prvoj laktaciji, u razdoblju između 110 i 140 dana, kada se kretala oko 23,6 mg/100ml. Na kraju prve laktacije prosječni sadržaj ureje u mlijeku je iznosio oko 21,6 mg/100ml. Drugu laktaciju karakterizira nešto veći sadržaj ureje, u razdoblju odmah nakon teljenja kada su zabilježene najviše vrijednosti od svih praćenih laktacija. Starost krava kod prvog teljenja je također imao utjecaj na sadržaj ureje u mlijeku. Krava koje su telile u dobi od 24. do 26. mjeseca imale su najvišu vrijednost sadržaja ureje koji je za navedeno razdoblje iznosio 23,2 mg/100ml. Najniža vrijednost sadržaja ureje je zabilježena kod krava koje su telile u dobi od 18. mjeseci i iznosila je ispod 20 mg/100ml. I sezona teljenja je utjecala na sadržaj ureje u mlijeku. U zimskoj sezoni 2004. godine zabilježene su najmanje vrijednosti sadržaja ureje u mlijeku, dok je u jesenskoj sezoni iste godine izmjeren najviši sadržaj ureje u mlijeku (24 mg/100ml). U narednim sezonama teljenja dolazi do opadanja sadržaja ureje u mlijeku. Razlike u sadržaju ureje u mlijeku utvrđene su između županija. Najviša vrijednost heritabiliteta (0,08) ocjenjena je modelom gdje je kao usporediva grupa korištena interakcija između stada i kontrolnog dana. U istraživanju, udio varijabilnosti pojašnjen interakcijom stado-dan kontrole, je iznosio 67%, dok je 25% varijabilnosti sadržaja ureje ostalo neprotumačeno. Ovaj je model korišten i pri procjeni uzgojne vrijednosti. Također je testiran i model gdje je utjecaj stada korišten kao usporediva grupa, te je ovim modelom ocijenjena najniža vrijednost heritabiliteta (0,03). U modelima gdje je interakcija između stada i godina testiranja korištena kao usporediva grupa ocjenjene su više vrijednosti heritabiliteta (0,04 i 0,05) u odnosu na prethodni model. Izračunate fenotipske korelacije između sadržaja ureje i osobina mliječnosti: dnevna količina mlijeka, dnevna količina i sadržaj masti i bjelančevina su bile statistički značajne (P <0,0001). Pozitivna i niska fenotipska korelacija (0,15) utvrđena je između sadržaja ureje i dnevne količine mlijeka, između sadržaja ureje i dnevne količine masti (0,10), te između sadržaja ureje i količine bjelančevina (0,16). Između sadržaja ureje i sadržaja mliječne masti koeficijent korelacije je bio nizak i negativan (-0,05) dok je između sadržaja ureje i sadržaja bjelančevina on bio nizak i pozitivan (-0,03).The aims of this paper were to determine to which extent the environmental factors (order and stadium of lactation, age with the first calving, calving season, region and herd) have the influence on the content of urea in milk, and connection of urea content in milk with other features of milk production with cows. The largest share of urea content in milk was recorded in the first lactation, in the period between 110 and 140 days, when it was around 23.6 mg/100ml. In the end of the first lactation the average urea content in milk was around 21.6 mg/100ml. The second lactation is characterized by somewhat bigger urea content, in the period immediately after calving when the highest values from all tracked lactations was recorded. The age of cows with their first calving also had an impact on urea content in milk. Cows that calved in the age from 24th to 26th month had the highest value of urea content, which was 23.2 mg/100ml for the stated period. The lowest value of urea content was recorded with cows that calved in the age of 18 months and it was below 20 mg/100ml. Season of calving also influenced the urea content in milk. In winter season 2004 the lowest values of urea content in milk were recorded, while in the autumn season of the same year the highest urea content in milk was measured (24 mg/100ml). In the following calving season increase of urea content in milk followed. The differences in urea content in milk were determined between the counties. The highest value of heritability (0.08) was estimated by the model where as a comparisson group the interaction between the herds and control day was used. In a research the share of variability was explained by the interaction herd-control day and it was 67%, while 25% of variability of urea content in milk remained unexplained. This model was used when estimating the breeding values. A model was also tested where the influence of herd was used as a comparisson group and by this model the lowest value of heritability was estimated (0.03). In models where interaction between the herd and years of testing was used as comparisson group higher values of heritability (0.04 and 0.05) were measured with respect to the previous model. Calculated phenotypical correlations between the urea content and milk production features: daily amount of milk, daily amount and content of fats and proteins were statistically significant (P <0.0001). Positive and low phenotypical correlation (0.15) was determined between the content of urea and daily amount of milk, between the urea content and daily amount of fat (0.10), and between urea content and amount of proteins (0.16). Between the urea content and content of milk fat the coefficient of correlations was low and negative (-0.05),while between the urea content and content of proteins it was low and positive (-0.03)

The calculation of phenotypic and genetic parameters for milk urea concentration in Holstein breeds

Heritability (0.08) was evaluated in a model whereas the comparable group was used the interaction between the herd and the control day. The influence of the herd was used as a comparable group and heritability (0.03). The interaction between herds and years of testing was used as a comparable group (0.04 and 0.05). Heritability (0.08) was evaluated in a model a comparable group was used the interaction between the herd and the control day. Phenotypic correlations between milk urea concentration and milking traits: daily quantity of milk, and the content of fat and proteins (P <0.0001). Positive and low phenotypic correlation (0.15) was found between the milk urea concentration and daily milk yield, between the urea concentration and the daily amount of fat (0.10). Between the urea concentration and milk fat content coefficient was (-0.05), between urea concentration and protein content (0.03)