in the present study, to estimate genetic parameters and genetic and phenotypic trends in holstein dairy cows in the north of iran, the records from first lactation of 11398 collected from 1989 to 2006 were used. records were collected from 290 herds. productive traits were 305 day-2x adjusted milk and fat yield and reproductive traits were age at first calving, calving interval and dry days. g...

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...

Data from insemination and calving events of Italian Holstein cows and heifers collected from January 1996 until December 2002 were used to estimate phenotypic and genetic parameter for some fertility traits. A validation procedure of the data based on gestation length and information on service sire was used. According to these procedure, in Italy 75.9 % of the calvings are associated to servi...

This research sought to determine the effect of selected milk protein polymorphisms on reproduction parameters 598 black and white Polish Holstein–Friesian cattle. The analyzed genes were kappa-casein (CSN3) beta-lactoglobulin (BLG). following reproductive indexes selected: age at first calving, interpregnancy period, calving interval, insemination index. influence identified genotypes course p...

the purpose of this research was the study of reproductive performance in postpartum dairy cows with different parities. twenty holstein dairy cows were assigned into two equal primiparous and multiparous groups. body weight and body condition score (based on 1-5 scoring) were measured every other week, starting from two weeks before calving till pregnancy confirmation. daily milk yield was als...

The objective of present study was to derive the economic values for number of inseminations to conception, calving interval, milk yield and stillbirth, using economic data of 10 Iranian Holstein herds. The economic values were derived by using the profit function methods and differentiating a profit equation with respect to the traits of interest. The cow fertility costs herd amortization or r...

Abstract This study was conducted to observe Bali cows’ primipara reproductive performance between natural mating and artificial insemination. Fifty cows owned by 44 farmers in Central Lombok Regency, West Nusa Tenggara Province, were used as the research sample at first mating; 19 subjected (NM) 31 insemination (AI). Farmer’s profile data, rearing system, (the age of puberty, mating, gestation...

F OR profitable milk production the dairy cow must reproduce regularly. An interval of i~ to 13 months between calves usually is considered satisfactory. Cows calving every i~ months or less had higher yields per day for the interval between calves than did cows that required more than ~ months before reproducing in studies by Gaines and Palfrey (i931) and Chapman and Casida (I935). This observ...

The study was conducted at Ardaita Agricultural Technical Vocational Education Training (ATVET) college dairy farm, to evaluate the reproductive performance of Holstein Friesian and its crosses with Boran cattle breeds. Data collected between 2000 and 2015 on reproductive traits (n=2632) were studied and analyzed using general linear model procedure. The overall estimated means for age at first...