In this research, 272977 test day records collected from 659 herds during years 2001 to 2011 by the Iranian animal breeding center were used. In the first section the ability of different models to predict daily milk yield from alternative milk recording was tested. The result showed that a complex model including noon milking time plus the effect of lactation curve of Ali and Schaeffer functio...

in this research, 272977 test day records collected from 659 herds during years 2001 to 2011 by the iranian animal breeding center were used. in the first section the ability of different models to predict daily milk yield from alternative milk recording was tested. the result showed that a complex model including noon milking time plus the effect of lactation curve of ali and schaeffer functio...

In pasture-based seasonal calving systems, failure to become pregnant during the breeding season results in important economic losses as maximum profit is attained by minimising costs and increasing the proportion of grass in the diet of the lactating dairy cow. In the United States, dairy producers primarily strive to maximise production potential but are becoming increasingly aware of the eco...

No report has been published on the economical losses associated with errors in oestrus detection in cows under Iranian intensive dairy management. The following study was carried out to determine the accuracy of oestrus detection by farmers using artificial insemination in Shiraz dairy farms. Milk samples were collected from 179 Holstein milking cows at the time of artificial insemination. Mil...

Farms that purchase replacement breeding cattle are at increased risk of introducing many economically important diseases. The objectives of this analysis were to determine whether the total number of replacement breeding cattle purchased by individual farms could be reduced by improving herd performance and to quantify the effects of such reductions on the industry-level transmission dynamics ...

Background: Metabolic profiles have been used in efforts to predict pre parturient problems and fertility, to diagnose metabolic diseases, and to assess nutritional status in dairy cows. These profiles may help to confirm the diagnosis of sub clinical diseases, to be aware of possible causes of infertility in the herds, or to monitor improvement in herd animals. OBJECTIVES: This study investiga...

Bovine viral diarrhoea virus (BVDV) is an important pathogen of dairy cattle. In this study, bulk milk samples representing a total of 4105 milking cows, from 18 dairy cattle herds in the suburb of Mashhad- Iran, were tested for presence of BVDV by the use of a nested reverse transcription polymerase chain reaction (Nested RT- PCR) assay. Non of the cows in the herds had been vaccinated against...

A deterministic model based on the gene flow method, considering the features of Iranian Holstein cattle population, was implemented in this study to evaluate the effect of altering the number of age-classes in the dams of future sire (DS) path and the number of dams required for breeding a young bull (YB), to be evaluated as future sire, on genetic gain and resultant economic efficiency of a g...

The objective of this study was to estimate the genetic parameters of milk protein yields in Iranian Holstein dairy cattle. A total of 1,112,082 test-day milk protein yield records of 167,269 first lactation Holstein cows, calved from 1990 to 2010, were analyzed. Estimates of the variance components, heritability, and genetic correlations for milk protein yields were obtained using a random reg...