This study was designed to determine the culling rates of 23 Holstein dairy herds (with an average size of180 cows per herd) in Neyshabur area in northeastern Iran over a period of three years from 2001 to 2003.The average annual culling rate was 13.1%, (98.5% involuntary and 1.5% voluntary). Of the total disposals(1612 cows), 53.48% were culled by the end of five years of age. Poor fertility w...

To prevent distribution of recessive alleles in dairy herds all bulls used for AI (Artificial Insemination) haveto be tested. In this study 26 blood and 4 semen samples were supplied from Iranian Holstein bulls used forAI. Genomic DNA was extracted from 100 μl of blood and 200 μl of semen. Samples were tested by Polymerase Chain Reaction-Restriction Fragment Length Polymorphism (PCR...

Typically, central milk recording data from dairy herds are recorded less than monthly. Over-fitting early in lactation periods is a challenge, which we explored in different ways by reducing the number of parameters needed to describe the milk yield and somatic cell count of individual cows. Furthermore, we investigated how the parameters of lactation models correlate between parities and from...

SARA is a common and serious problem in well-managed and intensive dairy herds or beef cattle operations, because of triggering other metabolic disorders and causing lactation-fertility losses. It is a metabolic disease in dairy cattle that occurs during early and mid-lactation and has traditionally been characterized by low rumen pH, but lactic acid does not accumulate as in acute lactic acid ...

background: mastitis is an important health disorder in dairy herds which affects milk production, animal reproduction and production. objectives: the aim of this study was to estimate the cumulative incidence of mastitis in dairy herds in tehran province.  methods: from 679 dairy herds in tehran province that have more than 50 animals, 32 dairy herds were selected randomly and animals that had...

Mycoplasma bovis (M. bovis) is a highly infectious pathogen of cattle causing pneumonia, polyarthritis, otitis, and less frequently, subcutaneous abscesses, abortions and meningitis. Ineffective drugs treatments, culling of infected cows and loss of milk production can lead to significant economic loss on dairy farms. The early detection of cows excreting M. bovis bacteria to prevent mastitis o...

Approximately 20% of the beef tonnage produced in the United States is derived from Holsteins, through harvested dairy beef or cull dairy cows (Randy Blach, Cattle-Fax, personal communication). This represents a significant contribution to the U.S. beef supply. More and more large commercial feed yards have seen the opportunity available with feeding Holstein steers. Inherent variation between ...

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...

The prevalence of Chlamydophila spp. was determined in a cross-sectional study carried out in 2007 using 100 randomly selected dairy herds in the western part of Germany. Ten dairy cows per herd were sampled in herds with fewer than 100 cows; in bigger herds, 10% of the cows were sampled. For the detection of Chlamydophila spp., vaginal swabs from early lactating dairy cows were analyzed using ...

BACKGROUND Bovine respiratory disease (BRD) is 1 of the 2 most important causes of morbidity and mortality in dairy calves. Surprisingly, field data are scant concerning the prevalence of respiratory pathogens involved in BRD in preweaned dairy calves, especially in small herds. OBJECTIVES To identify the main respiratory pathogens isolated from calves in Québec dairy herds with a high incide...