A study of various chemical treatments to remove lignin from coarse roughages and increase their digestibility

Abstract

Several delignifying agents, used in various paper-making processes, have been compared for their ability to remove lignin and increase the digestibility of several roughages in laboratory experiments using a spray method of treatment recently suggested by Wilson & Pigden (1964). The chemicals were dissolved in small quantities of water which were then used to moisten the roughage. No washing was done after treatment. Sodium hydroxide was the most effective chemical; at a rate of 10 g per 100 g of roughage, the lignin content of ground maize cobs was reduced by 26 % and rumen dry-matter digestibility increased by more than 100 %. Bleaching powder was as effective as sodium hydroxide in removing lignin, but residual chlorine apparently inhibited rumen microbial digestion.Maize cobs, wheat and paddy straws, sorghum stover and sugar cane tops, though of widely differing initial digestibility, were brought to an equal level of rumen digestibility if treated with 4 % or more of sodium hydroxide. Drying the treated roughage at 100 degrees instead of at room temperature increased digestibility only in the case of maize cobs. The alkali spray treatment was as effective in increasing the digestibility of chaffed as of ground wheat straw. Data are presented which show the amounts of residual alkali in treated roughage as a function of time after treatment and of concentration of alkali used in the treatment. Further, data are presented which show the loss of nutrients from treated roughage if washed as in the traditional method.

Phenolic Compounds in Roughages and Their Fate in the Digestive System of Sheep

“…Sheep fed the other materials digested lignin equally well. According to Chandra and Jackson (1971), the low pH produced during the ensiling process provides the conditions necessary for the cleaving of lignin-carbohydrate bonds (both benzyl ethers and esters). Phenolic acids which result from this treatment may bind to nitrogenous fractions.…”

Ammonium Hydroxide Treatment on Wheat Straw

“…Chemical treatment of crop residues has increased digestibility and improved nutritive value due to cell-wall disruption and by sol~biliza tion of hemicellulose (Chandra and Jackson, 1971;Fernandez and Greenhalgh, 1972;Waller, 1976), lignin {Chandra and Fernandez and Greenhalgh, 1972;Jones and Klopfenstein, 1967) and silica {Chandra Fernandez and Greenhalgh, 1~72). Improved cellulose digestibility (Garrett et al, 1974;Waller, 1976) as a result of swelling has also been reported.…”

Sugarcane‐derived animal feed

“…At this level of NaOH, the rumen dry matter digestibility of sugarcane tops is similar to that of maize cobs, wheat straw, paddy straw, or sorghum stover (Chandra and Jackson 1971). The treatment of sugarcane bagasse with 2% (w/w dry fiber) NaOH before inclusion in complete rations significantly enhances feed consumption, daily weight gain, and daily milk production by lactating dairy cows compared with untreated bagasse (Randel et al 1972).…”

“…The treatment of sugarcane tops with 10 wt% NaOH increases rumen dry matter digestibility to 86%, compared with only 56% in untreated sugarcane tops (Chandra and Jackson 1971). At this level of NaOH, the rumen dry matter digestibility of sugarcane tops is similar to that of maize cobs, wheat straw, paddy straw, or sorghum stover (Chandra and Jackson 1971).…”