the study was carried out at agarfa atvet college dairy farm to evaluate the reproductive performance of holstein friesian× arsi and holstein friesian ×boran cattle. for the study, records compiled from 1983 to 2012 at the agarfa dairy farm were used as original data. the effects of breed, bloodlines, season and parity on the reproductive traits were evaluated. data were analyzed using the gene...

Genetic and phenotypic (co)variances for mature equivalent yield of 4% FCM and calving interval were simultaneously estimated by REML for grade Holstein cows in first and second parity. Data were 305d mature equivalent lactation records and calving dates for 299,441 daughters of 2489 AI sires first calving from 1970 to 1985 in California, New York, or Texas. Data were divided into three time pe...

the aim of this study was to determine the factors affecting stillbirth and the consequences of stillbirth on longevity, production, and reproductive performance in holstein cows of iran. calving records from march 2000 to april 2009 comprising of 220,043 calvings on 102,199 cows in 33 herds were used. the results showed that 4.06% of the newborn calves died within 48 h of birth. the stillbirth...

effects of inbreeding coefficient on estimates of genetic parameters, breeding values and genetic trends for production traits (milk, fat and protein yields), reproduction traits (age at the first calving, interval between first insemination to conception, calving interval, interval between calving to first insemination, and calving ease) as well as longevity of holstein cattle in iran were stu...

Data collected from Jersey herd in the central highland environment of Ethiopia was used to estimate genetic parameter and trend analysis for reproductive/fertility traits. Totally, 11,933 reproductive records recorded during last 30 years were analysis. Traits studied NSC (number service per conception), DO (days open), CI (calving interval), AFC (age at first calving) AFS service). Genetic ph...

Trends since 1980 for calving age and calving interval, 2 factors that influence herd life, were examined by parity for 5 breeds of US dairy cattle. Calving data were from cows with records that passed edits for USDA genetic evaluations and were in herds that remained on Dairy Herd Improvement test. First-calf heifers calved at progressively younger ages over time, but the age decline was less ...

Estimates of genetic correlations were .17 between first lactation milk yield and concurrent calving interval, .10 between second lactation milk yield and first calving interval, and .82 between first and second milk yields. Corresponding phenotypic correlations were .27, .16, and .58. Heritability estimates were .27 and .25 for first and second lactations and .15 for calving interval. Estimate...

This study was performed to estimate the effect of age at first calving and first two calving intervals on productive life and life time profit in Korean Holsteins. Reproduction data of Korean Holsteins born from 1998 to 2004 and lactation data from 276,573 cows with birth and last dry date that calved between 2000 and 2010 were used for the analysis. Lifetime profit increased with the days of ...

this study was designed to investigate causes of culling in industrial dairy herds in fars province and to describe the pattern of reason-specific culling with respect to age of animal and interval from calving to culling. a total number of 9 dairy herds were selected for the study and information about culling reasons, birth date, last calving date and culling date was collected for culled cow...

A total of 1385 lactation records of Tharparkar cattle collected from LRS Chandan, Jaisalmer spreading over a period of 33 years were utilized to assess the effects of period and season of birth/calving on age at first calving, calving interval and service period and also studied effect of parity on calving interval and service period. The least-squares means were 1821.86 ± 37.022 days, 414.16 ...