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Feed intake research offers dual benefits to Alberta beef industry

Thanks to a new gene profiling technique, researchers are one step closer to objectively describing the potential productivity and profitability of cattle with regard to feed intake.

"Not only has this research furthered the development of gene profiling techniques, it has led to the discovery of a collection of candidate genes that have a potential role in regulating hunger and fullness in cattle," says Dr. David Glimm, the University of Alberta researcher who was a co-investigator for the study. The research was funded in part by the Canada Alberta Beef Industry Development Fund (CABIDF).

"Production costs and cattle productivity depend largely on feed intake and feed efficiency. That's why research to improve feed intake and efficiency is so important to the productivity and profitability of Alberta's beef industry," he says.

Glimm's team used a revolutionary gene profiling technique called restriction fragment-differential display (RF-DD) to study feed intake regulation in cattle. "In addition to its accuracy and reliability, RF-DD allows for high-throughput and can be performed on very small samples," says Glimm. "It is the method of choice for the discovery of gastrointestinal (GI) genes with potential roles in regulating feed intake of beef cattle, it also allows systematic evaluation of the expression of every gene in any bovine tissue or cell."

This approach represents an effective, leading-edge functional genomics strategy that promises to deliver a wealth of new information about aspects of beef cattle nutrition, gastroenterology, feeding behaviour, stress and disease processes, he adds.

Cattle eat because of physiological hunger. In response to digestion, cells in the GI tract send signals to the brain to slow or stop eating when the animal is physiologically full. However, researchers haven't determined exactly which feedback signals and which hormones are involved in controlling feed intake.

"We set out to find out how feed in the rumen impacts the expression of genes in the absorptive cells of the intestine," says Glimm.

First, Glimm and the research team used an endoscopy to probe the gut in order to develop a baseline of gut activity. From there, they began a pattern of feeding and fasting in order to determine physiological responses to both actions over time.

The power of this research came from its experimental design, says Glimm. "Rather than using a large group of animals and making comparisons, we used a small number of animals, and compared each one to its own baseline measurement of gut activity."

Looking at patterns of activity in individual animals, and comparing them to baseline activity, helps researchers avoid pursuing 'false positives' - findings in one animal that are anomalies - that may lead their research astray.

RF-DD revealed the presence of many differentially expressed genes in bovine intestinal cells. Using their evaluation of differential gene expression in the GI tract of fasted and fed cattle, researchers discovered a group of candidate genes of potential economic importance to the beef industry. Several of those genes have now been isolated and sequenced.

"We hope that further characterization of the candidate genes in more cattle and relevant breeds will lead to the development of molecular genetic markers that allow selection of cattle for superior feed intake ability," says Glimm.

"As well, the new technology that has resulted from this research reduces the time required for the gene expression process and allows for new gene discovery. This represents a valuable addition to the knowledge base and capability of beef researchers in Alberta."

CABIDF is a joint $16.4 million fund of Alberta Agriculture, Food and Rural Development and Agriculture and Agri-Food Canada. The Fund is administered by Alberta Beef Producers and has supported more than 50 projects in five major categories identified to benefit the Alberta beef industry.

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