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 ...

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 ...

AIM The present investigation was undertaken to study the reproduction performance and effect of non-genetic factors on reproduction performance of Jersey crossbred cows. MATERIALS AND METHODS Data on 355 Jersey crossbred cattle maintained at the Post-graduate Research Institute in Animal Sciences, Kattupakkam, Tamil Nadu, distributed over 30 years (1985 to 2014). The effect of various non-ge...

this experiment was conducted to evaluate reproductive indices and provide appropriate solutions to improve the reproductive efficiency of dairy cattle in kermanshah province. with reference to forty-eight dairy industrial herds available at different cities of the province, a questionnaire containing quantitative measures were completed to assessing the reproductive parameters of 5397 dairy co...

Records of 594 calving dates and 493 calving intervals collected from a herd of Retinta beef cows in southwest Spain were studied. Their efficacy as reproductive measures were compared when a long breeding season was utilized. Variables used were date of present calving (DOC), date of subsequent calving (DOSC), time from start of breeding season to calving (TBSC), interval to next calving (CI),...

this study was carried out to study the inbreeding coefficient and its effect on reproductive performance of dairy cows (age at first calving, calving interval and open days) in isfahan province. records of 31,977 (primiparous cows), 36,982 and 51,423 (multiparous cows) for age at first calving, calving interval and open days were used, respectively. the inbreeding coefficients of animals were ...

Variance and covariance components for milk yield, survival to second freshening, calving interval in first lactation were estimated by REML with the expectation and maximization algorithm for an animal model which included herd-year-season effects. Cows without calving interval but with milk yield were included. Each of the four data sets of 15 herds included about 3000 Holstein cows. Relation...