the main objective of the present study was to explore the feasibility of nonlinear mixed models to describe the somatic cell score (scs) lactation curves and to compare the fit of four nonlinear vs. two linear models when applied to scs lactation records in iranian holstein cows. the animal breeding center of iran provided the scc data. the data consisted of 445077 test-day observations from 6...

Components of (co)variance and genetic parameters were estimated by REML procedures from first lactation mature equivalent Holstein milk records from 54,604 Colombian, Mexican, and Puerto Rican cows and 198,079 US cows. The objective was to determine the cause of heterogeneous daughter response to sire selection for milk yield between the regions. Data from Latin America were partitioned by cou...

The objectives of this study were to estimate heritability of acetone concentration in milk, based on monthly samples of milk obtained as part of a routine milk testing program, and to evaluate the feasibility of using such data in a genetic evaluation program for selection against ketosis incidence. Milk samples were collected from January to December of 1999 in herds enrolled in the Ontario D...

Abstract. The purpose of the research is to study age retirement cows from herd, depending on various genetic and paratypical factors. Methods. was carried out according data a black-and-white breed dairy herd Chelyabinsk region. studied animals different ages were divided into groups relative live weight at first fruitful insemination, mothers bulls-producers Holstein lines. paper analyzes for...

the genetic parameters for milk production and milk fat traits for first to third parities were estimated using single, multi trait and repeatability models. the genetic parameters for test day milk records were also estimated using random regression model. the test day records and 305 day milk records of 17055 cows from 10 herds collected between years 1996-2007 in khorasan razavi province wer...

background: metabolic profiles have been used in efforts to predict pre parturient problems and fertility, to diagnose metabolic diseases, and to assess nutritional status in dairy cows. these profiles may help to confirm the diagnosis of sub clinical diseases, to be aware of possible causes of infertility in the herds, or to monitor improvement in herd animals. objectives: this study investiga...

the objective of the present study was to determine factors affecting body condition score (bcs) and its association with productive and reproductive performances in holstein cows. mixed model analysis was performed on monthly records of bcs from april 2006 to july 2012 comprising 34666 records from 3134 dairy cows in a large commercial dairy herd under arid climatic conditions of isfahan in ir...

The first-lactation milk records of 20,850 artificially sired Holstein cows and their darns were analyzed by a sire-by-herd, variance components model to determine if unequal numbers of records in the filled subclasses had any effect on the paternal half-sib correlatiou or the daughter-dam regression. The variance components were estimated with the number per subclass held constant at 1, 2, 3, ...

Enzootic bovine leukosis is a contagious disease of cattle caused by the retrovirus, bovine leukemia virus (BLV) and is the most common cause of malignant neoplasm in cattle. In order to facilitate surveillance of this disease in dairy herds, we developed a method to combine ELISA of milk collected during routine production testing with a prescribed sampling of cows that is independent of the p...

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 ...