For the current research the records of 62 farms in Isfahan province were available. To estimate genetic and phonotypic trends of reproductive traits such as age at first calving, calving interval, days open and number of insemination to conception rate the records of 63,866 cows including 167793 reproductive records were employed. Farms were covered by Vahdat industrial Agriculturists and Dair...

Genetic and environmental factors that might affect gestation length (GL) were investigated. Data included information from >11 million parturitions from 1999 through 2006 for 7 US dairy breeds. Effects examined were year, herd-year, month, and age within parity of conception; parturition code (sex and multiple-birth status); lactation length and standardized milk yield of cow; service sire; co...

Associations between rearing conditions and the risk of culling in dairy cows were studied by survival analysis. Data were collected from 1039 Swedish Red cows, 1029 Swedish Holsteins, and 56 cows of other milk or cross-breeds, representing all female animals born in 109 Swedish herds during 1998. Length of productive life was defined as the number of days from 1st calving to culling. The appli...

The aim of the present study was to estimate the genetic parameters and genetic trends of somatic cell score (SCS) in the first 3 lactations of Iranian Holstein cows by random regression (RR) animal model by using Restricted Maximum Likelihood (REML) method. The data set used in this analysis included observations of 340318 test-day records of 41526 cows in 288 herds; 89969 test-day of 11750 co...

With the aim of analysis the variability of somatic cell count (SCC) of dairy cattle in conditions of Mediterranean region in Croatia, 217,509 test-day records, collected from January 2005 until April 2010, were extracted from HPA (Croatian Agricultural Agency) database. Milk recording in Croatia occurs according to the AT4 milk recording method. Somatic cell count (SCC) in milk samples taken f...

the aim of the present study was to compare the occurrence and duration of clinical mastitis in different seasons, stages of lactation period and parities in a holstein dairy farm in iran. a retrospective epidemiological survey from april 2005 to march 2008 was conducted on 884 clinical mastitis cases of 7437 lactations. data of each case including calendar-date of mastitis onset, days in milk ...

Environmental effects on fertility measures early in lactation, such as the interval from calving to first luteal activity (CLA), proportion of samples with luteal activity during the first 60 days after calving (PLA) and interval to first ovulatory oestrus (OOE) were studied. In addition, traditional measurements of fertility, such as pregnancy to first insemination, number of inseminations pe...

Male calves and culled cows of dairy cattle are used for beef production. However, unlike beef breeds, the genetics of growth performance traits in dairy breeds have not been extensively studied. Here, we performed a genome-wide association study (GWAS) on Holsteins ( = 5,519), Jerseys ( = 1,231), and Red Dairy Cattle ( = 4,410) to identify QTL for growth traits. First, a GWAS was performed wit...