ABSTARCT The objective of this study was to analyze the effects of factors affecting reproductive traits in the Holstein population of the Isfahan dairy farms for subsequent compilation of the model for genetic evaluation as well as for herd management practice. A data set containing 99012 records were analyzed by a linear model with fixed effects of year , herd ,season, parity of dam, calving ...

The average dairy cow survives only three lactations, reducing the availability of replacement heifers. Prenatal losses occur due to early embryonic mortality (about 40%), later embryo loss (up to 20% in high-yielding herds) or abortion (about 5%). A recent survey of 19 UK herds showed that 7.9% of calves were born dead and 3.4% died within 1 month. During the rearing phase, 6.7% of animals wer...

In this study production, reproduction, population, management and economic parameters resulted from recording of 7 flocks with size 57 to 400 and 721 heads of camels in a cycle of reproduction, during three years from 2011 to 2013 were used to find out of the economic values of important traits in one hump camel in desert areas rearing system. The economic traits that appeared in profit equati...

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...

This study aimed to compare the longevity and productive lifetime traits between Shami Hol-stein cows under subtropical conditions, in addition assess effect of age at first calving (AFC), lactation milk yield (FLMY), year season on studied both breeds. The available data included 495 records for 1129 Holstein from birth disposal date during period 1982 2014.The were lifespan (LS), life (PL), c...