26 March 2010

4 minute read

North America

Five of the projects were selected from proposals received in response to the Foundation’s annual Request for Proposals. The sixth is directed research to develop a genome-guided computer-based mating programme for Jersey cattle.

Since 2000, the USJersey organisations have invested $491,890 in Jersey-specific research. Financial support for 2010 from the AJCC Research Foundation was $40,750, with the remaining $9,500 allocated by National All-Jersey Inc. Projects funded are summarised below.

Influence of SARA on milk used for cheesemaking

It is known that milk pH and urine pH respond to changes in diet and feed intake, and milk pH is a critical factor in cheesemaking, affecting coagulation time, speed of firming and maximal firmness. The relationships are, however, not well measured or understood.

This project will extend a recent finding that urine pH may serve as a practical diagnostic tool for subacute ruminal acidosis (SARA). Dr Michael R. Murphy of the University of Illinois, Urbana, will induce SARA in mid-lactation Jersey cows, then measure effects by feed intake, milk yield, milk composition, milk stability, milk pH and urine pH. The anticipated findings are that SARA will adversely affect both urine pH and milk quality, and help assess the extent of nutritional effects on characteristics of milk used for cheesemaking.

Testing Jersey-specific embryo freezing techniques

Work will continue at Dr Sam Prien’s laboratory at Texas Tech University to improve the survival rate of frozen Jersey embryos.

Prien and co-workers have determined that Jersey embryos weigh approximately 25 per cent less than those from other breeds, which led to the discovery that Jersey embryos have much higher inner-cellular lipid (fat) content compared to other breeds. The two findings suggest that cryopreservation media need to be modified in order to safely freeze Jersey embryos. Three strains of mice, one of which has naturally higher body fat content similar to Jersey cattle, will be used to produce 1,000 embryos for testing different formulations of cryoprotectants to be developed for this study.

Testing colostrum recommendations for Jersey calves

Current recommendations for achieving passive transfer of immunity through colostrum intake are based upon studies with Holstein calves. The team of Dr Aurora Villarroel, Oregon State University, and Dr Gabriel Calderon, practicing veterinarian in Boardman, Oregon, will undertake a field study with more than 1,200 calves to determine if that standard is correct for Jersey calves.

This follows previous research establishing that Jersey colostrum has higher levels of immunoglobulins compared to Holstein colostrum, and also takes into account inherent differences in calf size and metabolism between the two breeds. The team will determine whether, based upon calf morbidity and mortality, the concentration of IgG required for passive transfer of immunity is greater than current recommendations, thus potentially leading to new, Jersey-specific standards for colostrum management.

Johne’s disease studies

Current estimates are that at least 68 per cent of US dairy herds are infected with M. avium sp. paratuberculosis (MAP), the bacterium that causes Johne’s disease. Financial and genetic losses from this infection are significant and can be devastating to the dairy business.

Dr Eran Raizman of Purdue University will study MAP infection status in Jersey cows during late lactation or the dry period and relate this to the level of MAP bacterial shedding in their colostrum following calving. The study will determine if fecal culture and ELISA test results can be effectively used to predict shedding in cows’ colostrum, and help better understand calves’ risk of infection from colostrum ingestion.

Research by Dr Holly L. Neibergs at Washington State University has identified genetic markers that can predict resistance to MAP infections in Holstein cows. In this study, she will use genomic tools to identify gene mutations in Jersey cattle responsible for susceptibility to MAP infection. Once identified, the presence or absence of these mutations could be used to select Jersey cattle that are less susceptible to Johne’s disease.

Development of genome-guided mating programme

Accurate and inexpensive platforms for genotyping Jersey cows and heifers are now in development, with commercial availability on the near horizon. To enable owners to fully utilise this information, the American Jersey Cattle Association is beginning to develop value-added services useful for Jersey dairy herds of any size.

Dr Kent Weigel, University of Wisconsin-Madison, will develop and evaluate alternative strategies for genome-guided mate selection in the next generation of JerseyMate™. His analysis will utilise genotypes and phenotypes now available from over 3,200 Jerseys, including approximately 1,800 bulls with progeny test information. Key issues that will be studied include methods for computing genomic inbreeding and its cost, along with selection and weighting of chromosomes based on their effects on production, herd life, udder health and fertility traits. Projected completion of this work is late summer 2010.

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