Assessment of the breeding value of Holstein-friesian cows for milk performance traits by application of the selection index method.

Istraživanje je sprovedeno na grlima holštajn-frizijske i crno-bele rase koja su gajena na farmama Poljoprivredne korporacije Beograd. Istraživanjem je obuhvaćeno 5238 krava koje su ostvarile 10963 laktacija. Od ukupnog broja grla obuhvaćenih istraživanjem, 175 grla je odabrano za bikovske majke koje su ostvarile 400 laktacija. Sve krave su gajene na 6 farmi Poljoprivredne korporacije Beograd u periodu od 2006. do 2014. godine i predstavljaju potomke 61 bika. Istraživanjem su obuhvaćene sledeće osobine mlečnosti: trajanje laktacije, prinos mleka (kg), sadržaj mlečne masti (%), prinos mlečne masti (kg), sadržaj proteina (%), prinos proteina (kg) i prinos 4% mast korigovanog mleka. Osobine mlečnosti su posmatrane u celoj i standardnoj laktaciji. Istraživanjem su obuhvaćene i sledeće osobine plodnosti: trajanje servis perioda, trajanje međutelidbenog intervala i trajanje bremenitosti. Varijabilnost osobina ocenjena je metodom najmanjih kvadrata primenom GLM (General Linear Model) procedure u programskom paketu SAS. Ocena komponenti varijanse i kovarijanse izvršena je primenom SIRE modela u programskom paketu „VCE-6“. Priplodna vrednost ocenjena je metodom selekcijskog indeksa. Za konstrukciju jednačina selekcijskog indeksa korišćene su osobine mlečnosti posmatrane u standardnoj laktaciji (305 dana) i osobine plodnosti. Ekonomska vrednost osobina mlečnosti uključenih u selekcijski indeks predstavljena je kao relativna vrednost i izračunata na dva načina: (1) preko standardne devijacije, koji su predložili Falconer i Mackay (1996) i (2) preko heritabiliteta posmatranih osobina, koji predlaže Lamont (1991). U laktaciji koja je prosečno trajala 373,89 dana grla holštajn-frizijske rase proizvela su 8705,33 kg 4%MKM. Prosečan prinos mleka za celu laktaciju je 9452,52 kg sa 3,48% mlečne masti i 3,23% proteina. Prosečan prinos mlečne masti i proteina u celoj laktaciji je 328,29 kg odnosno 304,50 kg. Posmatrano po kategoriji grla trajanje laktacije bikovskih majki je 395,84 dana u toku koje su proizvele 10322,44 kg 4%MKM...The study was carried out on the Holstein-Friesian and Black and White animals, which were reared on farms of the Agricultural Corporation Belgrade. The study included 5238 cows that had realized 10963 lactation. Of the total number of animals involved in the study, 175 were selected for bull dams who had realized 400 lactations. All cows were reared on 6 farms of the Agricultural Corporation Belgrade in the period from 2006 to 2014 and represent the progeny/offspring of 61 bulls. The study included the following milk traits: lactation duration, milk yield (kg), milk fat content (%), milk fat yield (kg), protein content (%), protein yield (kg) and yield of 4% fat corrected milk. Milk properties were observed in the whole and standard lactation. The study included the following fertility properties: duration of service period, duration of calving interval and duration of gestation. The variability of the properties was evaluated using the least squares method using the GLM (General Linear Model) procedure in the SAS software package. The evaluation of the variance and covariance components was carried out using the SIRE model in the VCE-6 program package. Breeding value was evaluated by the method of selection index. For the construction of the equation of the selection index, the milk properties observed in the standard lactation (305 days) and fertility were used. The economic value of the milk properties included in the selection index is presented as the relative value and calculated in two ways: (1) through the standard deviation proposed by Falconer and Mackay (1996) and (2) through the heritability of the observed properties proposed by Lamont (1991). In the lactation lasting 373.89 days on average, the Holstein-Friesian animals produced 8705.33 kg of 4% FCM. The average milk yield for whole lactation was 9452.52 kg with 3.48% milk fat and 3.23% protein. The average yield of milk fat and protein in total lactation was 328.29 kg and 304.50 kg, respectively..