to estimate the genetic parameters for production and reproduction traits in holstein cows, information from 15 herds recorded by animal breeding center of iran during 1980 – 2004, were employed. estimations were made using restricted maximum likelihood method under an animal model ranging df-reml and matvec software. estimates of heritabilities for yield traits were moderate and ranged from 0....

Estimation of genetic trends is necessary to monitor and evaluate selection programs. The objective of this study was to estimate the genetic trends for milk yield in Iranian Holsteins cows using random regression test day model. Data set was consisted of 743205 test-day records from 1991 to 2008, which were collected by the Animal Breeding Centre of Iran. Breeding, environmental and phenotypic...

AIM The aim was to estimate genetic factors affecting the first lactation milk production traits in Kankrej cattle of North Gujarat. MATERIALS AND METHODS The 475 first lactation records of Kankrej cows that were maintained at the Livestock Research Station, Sardarkrushinagar Dantiwada Agricultural University, Sardarkrushinagar, Gujarat, over a period of 35 years from 1980 to 2014 were studie...

The data pertaining to variable production and reproduction traits of Murrah buffaloes (1980 lactation records of 698 Murrah buffaloes) were collected from the Central Cattle Breeding Farm, Alamadhi, Tamil Nadu, India. The overall leastsquares means (± SE) for peak yield, days to attain peak yield, 305-day milk yield, lactation length, lactation milk yield, service period, calving interval and ...

Increased genetic susceptibility to mastitis has accompanied the rapid genetic increase in milk yield, and genetic selection for mastitis resistance should be considered. Somatic cell score is recommended as an indicator trait to achieve genetic improvement for mastitis resistance. Heritability of somatic cell score is around 10%, and genetic correlation between somatic cell score and clinical ...

Estimates of genetic correlations were .17 between first lactation milk yield and concurrent calving interval, .10 between second lactation milk yield and first calving interval, and .82 between first and second milk yields. Corresponding phenotypic correlations were .27, .16, and .58. Heritability estimates were .27 and .25 for first and second lactations and .15 for calving interval. Estimate...

the objective of this study was to estimate genetic parameters coupled with genetic and phonotypic trends for age at first calving (afc), open days(od) and milk yield(my) of first lactation in iranian holstein cows. records of reproduction and production for genetic evaluation from 1984 to 2005 for afc, od and my were 71736, 20126 and 20126, respectively. single and two-variable animal models w...

Using monthly test day records the genetic parameters of Iranian Holstein cattle in first lactation were studied. Data of 277400 test-day milk records from 65320 cows and 2210 sires were analyzed by an animal random regression model using restricted maximum likelihood methodology. The model included herd-test-date, interaction between year-season of calving, days in milk (linear and quadratic) ...

in order to estimate the genetic parameters and comparison legendre polynomials for production traits of iranian holstein dairy cattle test-day records of first lactation cows for milk yield, fat yield, protein yield, fat percentage and protein percentage traits were used. these records collected from 2006 to 2010, by the animal breeding center of iran. the genetic parameters were estimated usi...