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Regulation of the ruminal environmen...

Mooney, Charles Steven.

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Regulation of the ruminal environment by lactating dairy cows.

紀錄類型:	書目-語言資料,印刷品 : Monograph/item
正題名/作者:	Regulation of the ruminal environment by lactating dairy cows./
作者:	Mooney, Charles Steven.
面頁冊數:	288 p.
附註:	Adviser: Michael S. Allen.
Contained By:	Dissertation Abstracts International67-10B.
標題:	Agriculture, Animal Culture and Nutrition. -
電子資源:	http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=3236376
ISBN:	9780542908248

Regulation of the ruminal environment by lactating dairy cows.
Mooney, Charles Steven.

Regulation of the ruminal environment by lactating dairy cows. - 288 p.

Adviser: Michael S. Allen.

Thesis (Ph.D.)--Michigan State University, 2006.

The ruminal environment must be regulated for the health and productivity of ruminants. Sodium is the most abundant cation in the ruminal solution and is the most likely candidate as the regulated ion. Three experiments were conducted to evaluate the role of strong ions in the ruminal environment. If sodium compounds are infused into the ruminal solution, rumination time is reduced markedly, however, these infusions may generate ruminal conditions that are not representative of normal physiological or nutritional conditions. In the first experiment, we hypothesized that additional dietary sodium at normal concentrations would reduce rumination time of dairy cows. Additional dietary sodium decreased rumination time as did additional dietary potassium indicating that the general decrease in rumination was caused by a tonic increase in ruminal osmolality. Sodium is often added to lactating dairy cow diets in the form of sodium bicarbonate. The benefits of sodium bicarbonate addition are well documented but the mechanism of its action has not been defined. In experiment two, addition of dietary sodium increased total tract neutral detergent fiber digestibility probably by an expansion of ruminal contents and slowing of passage of digesta from the rumen. These effects are likely only a component of the mechanism of sodium bicarbonate action in lactating dairy cows. In this experiment, the addition of dietary sodium bicarbonate did not affect ruminal pH or alter the site of starch digestion. Sodium is a strong ion and strong ions are one of the determinants of the pH of a solution. In experiment three, we hypothesized that strong ion concentrations in the ruminal solution would be related to ruminal pH. Ruminal pH was correlated positively with ruminal sodium concentration, the sum of ruminal sodium and potassium, and ruminal strong ion difference, and was correlated negatively with total volatile fatty acid concentration, ruminal ammonium, and the sum of ruminal ammonium plus potassium. Also, ruminal sodium concentration was negatively related to the sum of ruminal potassium plus ammonium concentrations. Therefore, the total concentration of cations is controlled, balancing ruminal acidity and limiting ruminal osmolality. A uniform, alkalizing strong ion difference was maintained in the ruminal solution across animals and dietary treatments and this plus the charge balance in the rumen are likely regulated by modifying sodium flux across the ruminal epithelium. Sodium, as well as bicarbonate, are likely key in the whole body regulation of the volatile fatty acid load. These experiments suggest that lactating dairy cows actively regulate the ruminal environment especially sodium in the ruminal solution.

ISBN: 9780542908248Subjects--Topical Terms:

1017857
Agriculture, Animal Culture and Nutrition.

Regulation of the ruminal environment by lactating dairy cows.
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