Introduction Kenya has one of the most successful dairy industries in sub-Saharan Africa based on some 3 million cattle of mostly high grade Bos taurus dairy breeds and a relatively advanced milk marketing infrastructure. The main breeds for dairy production are Friesian, Guernsey, Ayrshire and their crosses with the local East African Zebu (EAZ). The EAZ population is estimated at about 10 mil...

The spread of bovine virus diarrhoea virus (BVDV) in a closed dairy herd maintained under typical management conditions is studied using two approaches. In the first instance a stochastic computer model is used to simulate the month-to-month changes in the infection status of each animal. These results are contrasted with the results of a mass-action model which uses three differential equation...

A national US survey collected data on herd milk production and management of Holstein herds. Step-wise selection identified management practices that were related to herd milk production using only operations that calculated herd milk production as well as using data from all operations. Results were similar. Milk production was highest in the West. Operations with < 100 dairy cows had lower p...

Successful introduction of replacement gilts and boars into the breeding herd is an important aspect of breeding herd efficiency. To attain herd efficiency, females must ovulate adequate numbers of fertile ova, show willingness to mate (estrus) and conceive readily. Males must produce adequate numbers of fertile spermatozoa, possess ability and show willingness to mate and produce high concepti...

It is well known that transition cow diseases negatively affect reproductive performance; thus, profitability and welfare of dairy herds. Prevention of diseases at the herd level requires a constant effort and effective coordination of the total system (animals, environment, nutrition, and personnel). Substantial knowledge exists to prevent many diseases or conditions; however, it must be trans...

Replacement heifers, whether they are raised on the farm, purchased from other dairies, or raised by contract growers, are critical to herd productivity because they represent the future milking and breeding stock in all dairy operations. The goal should be to provide an environment for heifers to develop full lactation potential at the desired age with minimal expense. Animal health and well-b...

In the US, a major step forward in control of Johne’s disease (JD) was the development and implementation of the JD Herd Risk Assessment and Herd Management Plan. Along with a major educational effort, many herds have joined the US JD Herd Control Program, though many others remain outside of control programs. The focus of this report is to address the issue of control and eradication of Johne’...

In the past decade, the demand for organic agricultural products has increased rapidly in the United States and worldwide. Milk quality research is of major interest to both consumers and dairy farmers alike. However, scientific data on milk quality, herd management methods, and animal welfare on organic farms in the United States has been lacking before the research from this study. The object...

Individual lactation records from Holstein cows in 3449 herds participating in an AI stud's young sire sampling program from 1971 to 1987 were used to characterize the sampling program and to estimate genetic merit and trend. Average genetic merit of cows in sampling program herds was consistently superior to the average genetic merit of cows in the US population. Genetic trend of sires of firs...