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Exploring methods to help ruminants make better use of their food
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Professor Obtitsu conducts research on ruminant animals such as cattle and sheep. With the main emphasis on studies of ruminant feed and nutrition, he explores the combination of feed ingredients, feeding methods, and feed preparation to ensure effective use of livestock feed.
What initially interested him was the mechanism of the ruminant stomach. Ruminants are known to have a four-chambered stomach. The first chamber is particularly large, and together with the second chamber, functions as a “anaerobic fermenter.”
Professor Obitsu says, “In the first stomach of the cow, microbes decompose grass and other plant materials that humans cannot use, into small molecular compounds which are further fermented by microbes in the stomach. The resulting fermentation products are absorbed from the stomach and used as sources of energy and protein that enable them to grow and then produce milk. I thought this mechanism to be interesting.” |
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Rumination refers to the digestive process in which ruminants repeat the following: They swallow feed without chewing it well, and then bring the “cud” up to the mouth to chew it again, before passing it back to their stomach. According to the professor, cows cannot eat the next portion of feed, only after the part of stomach content moves out of the stomach ? however, this will not occur until the stomach contents are broken down into very small particles.
“For this reason, cows spend about six hours a day ruminating. I felt that cows were attractive in that they make effective use of grass in this manner,” he says.
Since the inside of the ruminant stomach is anaerobic, it is difficult to study the microbial function after the stomach contents being taken outside, making it a very tough task to clarify what is happening in the ruminant stomach. Consequently, despite many years of research, various things still remain unknown. This was also part of what interested him, says Professor Obitsu. |
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Making new research findings by tracing nutrients from ingested feed to output from body of cows
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Specifically, he takes the following approach in his research.
(1) First, measure the amount and constituents of the feed, excreta and products. A large cow, for example, eats 23 kg of feed in dry weight a day. When expressing the weight including moisture, this amount becomes around 50 kg, which is equivalent to that of the cow’s feces. The cow also produces 40 kg of milk a day. By measuring how much milk is produced from the feed, one can then estimate the amount of nutrients metabolized throughout the body per day.
(2) Second, take samples of the stomach contents and blood. Analyze what kind of metabolism occurs in respective body organs, such as the digestive tract, the liver, and the mammary glands. Occasionally, observe the metabolism in each segment of digestive tract.
In the above approach, the metabolic process at an intermediate stage, which cannot be grasped well just by checking the cow’s whole body in step (1), can be examined in detail in step (2). By tracing the intermediary metabolic process, the entire picture can be obtained. His research is characterized by this approach. |
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This study aims to achieve three major goals. One is to produce positive results for the benefit of farmers. He says that “By considering the optimal dietary conditions and feeding methods, I hope that our research will help to save feeding costs, increase the production, and improve the quality of dairy products.”
The second goal is to make new biological discoveries. He continues, “Our research also aims to find more about the mechanism in ruminant nutrition, which has still many unclear points, and to obtain new findings.”
The third goal is to contribute developing sustainable animal production system. Professor Obitsu explains that “Cows produce methane gas in their stomach as a digestive by-product. Methane is a well-known greenhouse gas, and effect of methane emission from cows on global warming is a matter of concern. Cows obligatory release methane gas due to the functions of microbes in their stomach. About 10% of feed energy is lost as methane in exhaust gas. If that energy can be utilized for production, it would improve energy efficiency and reduce environmental impact. I am therefore pursuing research to minimize methane emissions from cows.” The professor adds that he also seeks to reduce the excretion of nitrogen and phosphorus in urine and feces, by enhancing utilization of these components by animals. |
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Addressing diverse research themes, including milking robots and chlorophyll, from a broad perspective
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At present, Professor Obitsu strives to develop technologies for stable and high-productive dairy farming using an automatic milking system, as a project subsidized by the Ministry of Agriculture, Forestry and Fisheries. This project has incorporated the effective use of a so-called “milking robot” introduced on a farm of Hiroshima University.
He states that “By conventional methods, cows can be milked up to three times a day at maximum. By contrast, if using a milking robot, which is capable of milking anytime the cows need to be milked, we can take milk many times a day since the robot saves labor. Since olden times, it is found that increasing the milking frequency can increase the milk yield. Accordingly, the use of milking robots would increase the milking frequency, which was not possible before due to the labor issue. However, frequent milking may increase nutritional demand for milk production. I therefore carry out research to investigate the nutritional status of cows and consider more appropriate feeding ways.”
About his future plans, he says that “So far, we have focused on improving productivity and efficiency. However, we need to shift our research focus to contributing to healthy cow feeding and to reducing hard tasks of dairy farmers. ” The professor expresses his wish that, as a whole, his research leads to enhanced efficiency and labor savings.
Professor Obitsu is also worried about the decline in the production of domestic forage feed in Japan. Recently he started the study on chlorophyll in forages, as well. “I believe that if we can discover novel advantages of forages, it would encourage the use and production of the forages. Conventionally we have looked only at the major nutrients of grass. Research into chlorophyll, which makes the grass look green, has revealed that a part of the chlorophyll molecule has physiological functions which may have an impact on cow health, I am now pursuing research in that area,” says the professor.
For young people who are hoping to study at Hiroshima University in the future, he sends an encouraging message of, “I want you to have a broad perspective.”
He stresses that “In doing research, many people tend to look at specifics, but it is important to consider what roles these specifics play in the overall research subject. I hope that students will conduct research from a broad perspective, without looking too much at details. I began studying chlorophyll as mentioned earlier when I started wondering what makes grass look green. I believe that taking such an attitude is necessary in everything.” |
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| Taketo Obitsu |
Professor
Laboratory of Animal Nutrition and Feeding
April 1, 1987 ? January 31, 1995 Research Assistant, School of Applied Biological Science, Hiroshima University
February 1, 1995 ? March 31, 2002 Associate Professor, School of Applied Biological Science, Hiroshima University
April 1, 2002 ? March 31, 2007 Associate Professor, School of Applied Biological Science, Hiroshima University
April 1, 2007 ? March 31, 2015 Associate Professor, School of Applied Biological Science, Hiroshima University
April 1, 2015 ? present Professor, School of Applied Biological Science, Hiroshima University
Posted on Oct 13, 2015
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