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Publication Date
1981
Description
Research on sodium hydroxide (NaOH) treatment oflow-quality roughages generally indicates that in-vivo digestion is lower than in-vitro digestion. The purpose of this research was to identify factors that may cause less of the potentially digestible fiber to be digested in vivo than in vitro. Corn (Zea mays) cobs were raised to 60% moisture and treated to contain 0%, 2.5%, 5.0%, 7.5 % , and 10.0% NaOH. Lambs were fed diets containing 80% cobs and 20% supplement, giving a complete mixed diet con· taining 0%, 2.0%, 4.0%, 6.0%, and 8.0% NaOH. Five abomasally cannulated lambs were assigned to a 5 x 5 Latin square to measure ruminal fiber digestion as affected by increasing level of NaOH. In-vitro digestibility of NDF reaching the abomasum increased linearly with increasing level of treatment. Rate of passage and rate of ruminal fiber digestion were measured in 15 ruminally fistulated lambs fed the same diet as in the previous trial to determine if these parameters could account for the difference in fiber digestion. Chromic oxide was used as an external marker, and rumen samples were collected at 3, 6, 12, 24, 48, and 96 hours postdosing to measure rate of passage. As level of NaOH increased, rate of passage increased linearly (P < 0.05). Mean ruminal retention time decreased from 46.8 hours for the control diet to 29.8 hours for the 8% NaOH diet. When rate of passage was regressed against NaOH level, the slope of the line was 0.142 %/hour with r2 = 0.733. Nylon bags containing 0.15 g cotton fiber were used to measure the rate of ruminal fiber digestion in lambs fed the five NaOH-treated diets. Bags were re· moved from the rumen after 12, 24, 36, and 48 hours, and the loss in weight was used to estimate ruminal digestion. As level of NaOH increased from 0% to 8.0%, rate of ruminal cotton fiber digestion decreased from 5.42 % to 2.15 %/hour. When rate of cotton digestion was regressed against NaOH level, the slope of the line was - 0.488%/hour with r2 = 0.934. These data suggest that the increased rate of passage and decreased rate of ruminal fiber digestion may explain many of the differences observed between in-vitro and in-vivo digestion of NaOH-treated roughages.
Citation
Berger, L L.; Klopfenstein, T J.; and Britton, R A., "Factors Causing Greater In-Vitro than In-Vivo Digestibility of Sodium Hydroxide - Treated Roughages" (1981). IGC Proceedings (1977-2023). 2.
(URL: https://uknowledge.uky.edu/igc/1981/section10/2)
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Factors Causing Greater In-Vitro than In-Vivo Digestibility of Sodium Hydroxide - Treated Roughages
Research on sodium hydroxide (NaOH) treatment oflow-quality roughages generally indicates that in-vivo digestion is lower than in-vitro digestion. The purpose of this research was to identify factors that may cause less of the potentially digestible fiber to be digested in vivo than in vitro. Corn (Zea mays) cobs were raised to 60% moisture and treated to contain 0%, 2.5%, 5.0%, 7.5 % , and 10.0% NaOH. Lambs were fed diets containing 80% cobs and 20% supplement, giving a complete mixed diet con· taining 0%, 2.0%, 4.0%, 6.0%, and 8.0% NaOH. Five abomasally cannulated lambs were assigned to a 5 x 5 Latin square to measure ruminal fiber digestion as affected by increasing level of NaOH. In-vitro digestibility of NDF reaching the abomasum increased linearly with increasing level of treatment. Rate of passage and rate of ruminal fiber digestion were measured in 15 ruminally fistulated lambs fed the same diet as in the previous trial to determine if these parameters could account for the difference in fiber digestion. Chromic oxide was used as an external marker, and rumen samples were collected at 3, 6, 12, 24, 48, and 96 hours postdosing to measure rate of passage. As level of NaOH increased, rate of passage increased linearly (P < 0.05). Mean ruminal retention time decreased from 46.8 hours for the control diet to 29.8 hours for the 8% NaOH diet. When rate of passage was regressed against NaOH level, the slope of the line was 0.142 %/hour with r2 = 0.733. Nylon bags containing 0.15 g cotton fiber were used to measure the rate of ruminal fiber digestion in lambs fed the five NaOH-treated diets. Bags were re· moved from the rumen after 12, 24, 36, and 48 hours, and the loss in weight was used to estimate ruminal digestion. As level of NaOH increased from 0% to 8.0%, rate of ruminal cotton fiber digestion decreased from 5.42 % to 2.15 %/hour. When rate of cotton digestion was regressed against NaOH level, the slope of the line was - 0.488%/hour with r2 = 0.934. These data suggest that the increased rate of passage and decreased rate of ruminal fiber digestion may explain many of the differences observed between in-vitro and in-vivo digestion of NaOH-treated roughages.
