The present study was undertaken to estimate the various measures of lactation persistency and effect non-genetic factors affecting milk production comparison different indices using standard error as percentage mean in Tharparkar cattle. Total 322 records 138 cattle were collected from Animal Genetics Breeding Division National Dairy Research Institute, Karnal 1996 2018 for estimation persiste...

Animals with the same lactation breeding value can have different shapes of additive genetic curve, implying differences in persistency lactation. Since environmental conditions change across lactation, animals re-rank through leading to genotype by environment interaction for daily milk yield. The objectives this project is describe curve pattern estimated values and assess extent sire cow re-...

the aim of this study was to investigate the effect of milking frequency (three times daily vs. two times daily) on the lactation curve shape, partial and 305-d lactation performance in holstein dairy cows in iran. data from february 2000 to december 2012 comprising 217345 lactations on 141364 cows distributed in 324 herds collected by the animal breeding center of iran were used. the mean milk...

Many governments have signed up to greenhouse gas emission (GHGE) reduction programmes under their national climate change obligations. Recently, it has been suggested that the use of extended lactations in dairy herds could result in reduced GHGE. Dairy GHGE were modelled on a national basis and the model was used to compare emissions from lactations of three different lengths (305, 370 and 44...

variace / covariance components of 227118 first lactaiom test-day milk yield records belonged to 31258 iranian holstein cows were estimated using nine random regression models. afterwards, different measures of persistency based on estimation breeding value were evaluated. three functions were used to adjust fixed lactation curve: ali and schaeffer (as), quadratic (le3) and cubic (le4) order of...

The aim of this study was to investigate the effect of milking frequency (three times daily vs. two times daily) on the lactation curve shape, partial and 305-d lactation performance in Holstein dairy cows in Iran. Data from February 2000 to December 2012 comprising 217345 lactations on 141364 cows distributed in 324 herds collected by the Animal Breeding Center of Iran were used. The mean milk...