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Optimum sodium hydroxide and calcium hydroxide treatment of wheat straw for lactating dairy cows
Abstract
The objectives of these experiments were to determine the optimal combination of NaOH and Ca(OH)$\sb2$ for maximizing 48-h digestion of wheat straw, to characterize the effect of alkali combinations on NDF digestion kinetics and bacterial populations in vitro, and finally, to evaluate the effect of the optimum combination treatment of wheat straw selected from experiment 1 on ruminal function, DMI, and milk production in dairy cows. In experiment 1, ground wheat straw was treated with 0, 1, 2, 3, 4, or 5% (DM basis) NaOH and (or) Ca(OH)$\sb2$ in a 6 x 6 factorial arrangement. Selected treatments from this experiment were chosen for further investigation. In experiment 2, four ruminally fistulated Holstein cows were fed four diets that contained 0, 20, 30, or 40% (DM basis) wheat straw treated with 3% NaOH and 3% Ca(OH)$\sb2$ in a 4 x 4 Latin square design. In experiment 3, twelve midlactation Holstein cows were fed the 0 and 20% treated wheat straw to measure longer term lactation performance during a 12-wk period. A combination of 3% NaOH and 3% Ca(OH)$\sb2$ resulted in 48-h in vitro NDF digestion that was equivalent to combinations containing greater concentrations of NaOH. Alkali treatment decreased lag time and increased extent of NDF digestion whereas fractional rate of digestion remained unchanged. Scanning electron microscopy revealed that chains of diplococci, indicative of Ruminococcus flavefaciens, were virtually absent from all micrographs other than straw treated with Ca(OH)$\sb2$. For the control and 5% NaOH treatments, incubation at pH 5.5 appeared to select for a large proportion of rod-shaped bacteria. In experiment 2, no effect of treatment was observed on ruminal pH (6.45), osmolarity (323 mOsm/L), in situ digestion kinetics of wheat straw NDF, and 4% FCM (23.3 kg/d). However, DMI was significantly depressed for the two highest levels of treated wheat straw and was associated with a significant loss of BW. In experiment 3, no effect was observed for inclusion of 20% alkali-treated wheat straw on DMI (21.2 kg/d), BW (607 kg), milk production (23.8 kg/d), 4% FCM (25.4 kg/d), and milk composition. These results show that 3% NaOH and 3% Ca(OH)$\sb2$ is as effective as 5% NaOH alone, and that inclusion of up to 20% wheat straw treated with 3% NaOH and 3% Ca(OH)$\sb2$ in midlactation diets resulted in ruminal function and performance equivalent to alfalfa haylage.
Subject Area
Livestock
Recommended Citation
Haddad, Serhan George, "Optimum sodium hydroxide and calcium hydroxide treatment of wheat straw for lactating dairy cows" (1996). ETD collection for University of Nebraska-Lincoln. AAI9637069.
https://digitalcommons.unl.edu/dissertations/AAI9637069