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Effect of rumenpH on rates of fiber ...

Spackman, Clair.

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Effect of rumenpH on rates of fiber hydrolysis in Holstein heifers.

Record Type:	Electronic resources : Monograph/item
Title/Author:	Effect of rumenpH on rates of fiber hydrolysis in Holstein heifers./
Author:	Spackman, Clair.
Description:	145 p.
Notes:	Source: Dissertation Abstracts International, Volume: 66-04, Section: B, page: 1796.
Contained By:	Dissertation Abstracts International66-04B.
Subject:	Agriculture, Animal Culture and Nutrition. -
Online resource:	http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=3171908
ISBN:	9780542085970

Effect of rumenpH on rates of fiber hydrolysis in Holstein heifers.
Spackman, Clair.

Effect of rumenpH on rates of fiber hydrolysis in Holstein heifers. - 145 p.

Source: Dissertation Abstracts International, Volume: 66-04, Section: B, page: 1796.

Thesis (Ph.D.)--University of California, Davis, 2005.

The objectives of this study were to determine the effects of rumen pH and forage type on rates of fiber hydrolysis in the rumen of Holstein heifers. Rumen and duodenal cannulated pregnant heifers (n = 8) were sequentially fed 8 unbuffered diets containing 100, 80, 60 and 40% oat (OH) or alfalfa (AH) hay. The remaining portion of each diet was a concentrate mix. All animals were housed individually and fed twice a day at 8am (0h) and 6pm. Experimental periods lasted 18 d. Starting on d 8, Cr2O3 equal to 1.5% of diet fed on an as-fed basis was added to the rumen at each feeding. On day 15, fiber bags (ANKOMF57) containing samples of ground hay to match the forage in the diet were incubated in the rumen starting at Oh and were removed at 2, 4, 6, 8, 10, 12, 16 and 24 h. After removal, bags were washed with tap water 6 times for 1 min in an Ankom Fiber Analyzer at room temperature. Rumen pH was recorded every 15 mins for 24 h starting at 0h on day 15, by an in dwelling pH probe (Model 450CD, Sensorex, Garden Grove, CA) inserted through the rumen cannula. Duodenal and fecal samples were collected on d 15 at 1030 h, d 16 at 1530 h, d 17 at 0100 h, d 17 at 2000 h and d 18 at 0600 h and composited by cow. All samples were frozen at -16°C until analyzed. Feed, refusals, Ankom bags, duodenal and fecal samples were analyzed for DM, ash, NDF, ADF, and lignin. The analyses used The Ankom200 Fiber Analyzer (Ankom technology, 140 Turk Hill Park, Fairport, NY 14450) and the associated recommended procedures and calculations were used for NDF, ADF and acid detergent Lignin (ADL) analyses. Rumen pH was below pH 6 for up to 12 h/d. An interaction between hay-type and hour post-feeding effected rumen pH (P < 0.05). Average pH over 8 h post-feeding was found to be correlated to the rate of fiber disappearance. Rates of hydrolysis were lower for OH than AH even though OH was incubated in a less acidic environment. This suggests that the chemical, physical and architectural structure of the plant fiber can have a major effect on its rate of hydrolysis. This research has shown us that fiber hydrolysis does occur at rumen pH values in vivo much lower than has historically been accepted.

ISBN: 9780542085970Subjects--Topical Terms:

1017857
Agriculture, Animal Culture and Nutrition.

Effect of rumenpH on rates of fiber hydrolysis in Holstein heifers.
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245 1 0 $a Effect of rumenpH on rates of fiber hydrolysis in Holstein heifers.
300 $a 145 p.
500 $a Source: Dissertation Abstracts International, Volume: 66-04, Section: B, page: 1796.
500 $a Adviser: R. L. Baldwin.
502 $a Thesis (Ph.D.)--University of California, Davis, 2005.
520 $a The objectives of this study were to determine the effects of rumen pH and forage type on rates of fiber hydrolysis in the rumen of Holstein heifers. Rumen and duodenal cannulated pregnant heifers (n = 8) were sequentially fed 8 unbuffered diets containing 100, 80, 60 and 40% oat (OH) or alfalfa (AH) hay. The remaining portion of each diet was a concentrate mix. All animals were housed individually and fed twice a day at 8am (0h) and 6pm. Experimental periods lasted 18 d. Starting on d 8, Cr2O3 equal to 1.5% of diet fed on an as-fed basis was added to the rumen at each feeding. On day 15, fiber bags (ANKOMF57) containing samples of ground hay to match the forage in the diet were incubated in the rumen starting at Oh and were removed at 2, 4, 6, 8, 10, 12, 16 and 24 h. After removal, bags were washed with tap water 6 times for 1 min in an Ankom Fiber Analyzer at room temperature. Rumen pH was recorded every 15 mins for 24 h starting at 0h on day 15, by an in dwelling pH probe (Model 450CD, Sensorex, Garden Grove, CA) inserted through the rumen cannula. Duodenal and fecal samples were collected on d 15 at 1030 h, d 16 at 1530 h, d 17 at 0100 h, d 17 at 2000 h and d 18 at 0600 h and composited by cow. All samples were frozen at -16°C until analyzed. Feed, refusals, Ankom bags, duodenal and fecal samples were analyzed for DM, ash, NDF, ADF, and lignin. The analyses used The Ankom200 Fiber Analyzer (Ankom technology, 140 Turk Hill Park, Fairport, NY 14450) and the associated recommended procedures and calculations were used for NDF, ADF and acid detergent Lignin (ADL) analyses. Rumen pH was below pH 6 for up to 12 h/d. An interaction between hay-type and hour post-feeding effected rumen pH (P < 0.05). Average pH over 8 h post-feeding was found to be correlated to the rate of fiber disappearance. Rates of hydrolysis were lower for OH than AH even though OH was incubated in a less acidic environment. This suggests that the chemical, physical and architectural structure of the plant fiber can have a major effect on its rate of hydrolysis. This research has shown us that fiber hydrolysis does occur at rumen pH values in vivo much lower than has historically been accepted.
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650 4 $a Agriculture, Animal Culture and Nutrition. $3 1017857
650 4 $a Biology, Animal Physiology. $3 1017835
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