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...

in the research the genetic investigation productive and reproductive traits and changes trend the traits in years, seasons and different lactation periods and genetic evaluation cows and bulls of 785 records for milk and 665 records for fat yield and reproductive information during years 1998 to 2003 of 207 dairy cows ghezlagh farm aboureyhan campus (university of tehran) studied. the least sq...

this study was carried out to investigate the relationship between early lactation curve parameters andcalving interval in holstein cows of iran. in order to describe the lactation curve, the incomplete gammafunction was fitted to 5,754,428 test-day milk records corresponding to 766,108 lactations on 315,634 cowsin 2,448 herds. cows with higher milk yield during early lactation had shorter calv...

the reproductive performance of a dairy herd has a significant effect on the profitability of that herd. common measures of reproductive performance are days to first service, days to conception, calving interval, services per conception, conception rate, estrus detection rate, and pregnancy rate. most cow operations would benefit economically by reducing the number of operational days, decreas...

A total number of 1243 records of calving cases of 585 dairy Friesian cows during 8 consecutive years from 1997 to 2004 collected from Sakha Animal Production Research Station belonging to Animal Production Research Institute, Agriculture Research Center were used to study the effect of sire, live body weight (LBW) and age of dam and calving season on twinning rate and its consequent effects on...

emphasis on milk yield (my) as well as milk yield persistency (myp) and calving interval (ci) is necessary to achieve more sustainable productionin dairy cattle. therefore the main objective of this study was to find an optimum regression model to estimate economic values for my, myp and ci.using a deterministic bio-economic model, seventyfiveproduction states differing mainly in my, mypand ciw...

A study was carried out to evaluate non genetic factors affecting milk yield and milk composition in Zimbabwean Red Dane and Jersey cattle cattle. A total of 1004 and 10 986 unedited Red Dane and Jersey 305-day lactation records respectively, were obtained from Livestock Identification Trust (LIT) containing 22 herds (1 Red Dane herd and 21 Jersey herds), with Red Dane calving in the period 200...