this study utilized daily records of 2000 egyptian holstein dairy cows. the productive, reproductive and economic data during a whole lactation season were recorded for healthy and mastitis cows. two risk factors for mastitis were included, parity and season of calving. mastitis cows had significant (p

Data containing 14,188 lactation and reproductive records of Korean Holstein cows at first parity distributed across 3734 herd-year-season groups were analyzed to get genetic (co)variance estimates for milk yield, fat yield, calving ease, and days open. Milk and Fat yields were adjusted to 305 d. Heritabilities and genetic correlations were estimated in two different animal models on which were...

A similar proportion of beef cows and heifers exposed to estrous synchronization (ES) and artificial insemination (AI) became pregnant during the breeding season, compared with females bred via natural service breeding. Females in a breeding system that included ES and AI calved earlier in the calving season, compared with females bred with natural service, but no advantage was present for weig...

Data on productive and reproductive performance of cows in dual-purpose herds were analyzed to determine the effect of some environmental and genetic factors on saleable milk yield (SMY), lactation length (LL), daily saleable milk per lactation (DMYL), calving interval (CI), and daily saleable milk per calving interval (MYCI) in dual-purpose herds in Yucatan, Mexico. Repeatabilities (re) for th...

Calving traits for frequently used dairy breeds and crossbreeds were investigated using calving records collected in Australia over a period of 18 years. Dystocia (calving difficulty) was highest for heifers calving to Holstein-Friesian bulls, and Jersey calves caused the least dystocia. Incidence of dystocia in Holsteins was influenced by the season (gestation lengths were longer in winter, re...

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...

To investigate the effects of certain factors on the rate of retained placenta, 2844 calving records from 1288 Holstein cows in a herd were used. These cows calved during year period of 2001 to 2007. A generalized statistical linear model was applied to analyze the data. Logistic regression model was applied as the statistical model. In the model, fixed effects of year, season (warm or cold) an...

A 4-yr study using 217 cows/yr (3/4 Red Angus, 1/4 Simmental) evaluated effects of calving date and wintering system on cow and calf performance from birth to harvest. Cows were assigned to 1 of 5 treatments: 1) March (Mar) calving cows wintered on native range, 2) Mar calving cows wintered on corn residue, 3) June (Jun) calving cows wintered on native range, 4) Jun calving cows wintered on cor...