Effect of ammonia fiber expansion on the available energy content of wheat straw fed to lactating cattle and buffalo in India

Abstract

The seasonal lack of availability of lush green forages can force dairy farmers in developing nations to rely on crop residues such as wheat and rice straw as the major feed source. We tested whether ammonia fiber expansion (AFEX) treatment of wheat straw would increase the energy available to Murrah buffalo and Karan-Fries cattle consuming 70% of their diet as wheat straw in India. Forty lactating animals of each species were blocked by parity and days in milk and randomly assigned to 1 of 4 treatment diets (n = 10). Treatments were a nutrient-rich diet with 0 to 20% straw (positive control; PC) and 3 high-straw diets with various levels of AFEX-treatment: (1) 70% untreated straw (no AFEX), (2) 40 to 45% untreated straw with 25 to 30% AFEX-treated straw (low AFEX), and (3) 20% untreated straw with 50% AFEX-treated straw (high AFEX). The AFEX-treated straw was pelleted. Urea was added to the no and low AFEX diets so they were isonitrogenous with the high AFEX diet. Animals were individually fed the PC diet for 14 d followed by 7 d of adaptation to treatments, full treatments for 28 to 35 d, and finally PC diets for 21 d. Compared with buffalo fed the PC diet, those fed high-straw diets consumed 29% less feed dry matter, put out 16% less milk energy, and lost 0.8 kg/d more body weight; the AFEX treatment of straw did not alter intake or milk production but greatly ameliorated the body weight loss (-1.0 kg/d for no AFEX and -0.07 kg/d for high AFEX). In Karan-Fries cattle, high-straw diets decreased dry matter intake by 39% and milk energy by 24%, and the high AFEX diet increased intake by 42% and milk energy by 18%. The AFEX treatment increased digestibilities of organic matter, dry matter, neutral detergent fiber, acid detergent fiber, and crude protein by 6 to 13 percentage points in buffalo and 5 to 10 points in cattle. In conclusion, AFEX treatment increased the digestibility and energy availability of wheat straw for lactating buffalo and cattle and has commercial potential to improve milk production and feed efficiency when high-quality forages or grains are not available.

Symposium review: Technologies for improving fiber utilization

“…Feeding trials with lactating dairy cows using AFEX-treated rice straw have shown adequate intake and no adverse health effects with the treated material (Weimer et al, 2003;Blummel et al, 2014). Recently, Mor et al (2018) reported improved nutrient digestibility (DM, OM, CP, NDF, and ADF) of AFEXtreated wheat straw for lactating buffalo and cattle, underscoring its commercial potential as an alternative to high-quality forages or grains. However, acetamide, a co-product of the AFEX treatment produced during cleavage of acetyl groups from hemicellulose (Weimer et al, 1986), is not volatile, rather it can remain with the treated biomass thereby increasing its N content (Bals et al, 2011).…”

“…Nevertheless, research on the effects and fate of residual acetamide in cattle fed AFEX-treated forages are needed to ensure that meat and milk are not contaminated. Recent animal trials have not reported adverse health effects (Blummel et al, 2014;Griffith et al, 2016;Mor et al, 2018). The main advantages of AFEX treatment over traditional ammoniation method include safety, as the pellets generated are benign, ease of transport due to density of the pellets, and recycling of the ammonia.…”

Presence of Acetamide in Milk and Beef from Cattle Consuming AFEX-Treated Crop Residues

“…Details of these trials can be found in Mor et al. 9 Animals were housed in individual pens and fed ad libitum with 10 animals per treatment. In both trials animals were on a control diet for 3 weeks before transitioning to the treatment diet using AFEX-treated wheat straw pellets.…”

“…5 Ammoniation makes the cellulosic sugar polymers in crop residues more accessible to hydrolytic enzymes and also increases the inorganic nitrogen content, which result in increased digestibility of the crop residues in vitro 6−8 and in vivo. 9…”

Scale‐up and operation of a pilot‐scale ammonia fiber expansion reactor

“…In addition to biofuels feedstock, AFEX‐treated crop residues have been fed to ruminant animals such as sheep, goats, cattle, and buffalo (Mor et al, ; Mor et al, ). The opportunity to utilize AFEX‐treated crop residues in both biofuel feedstock and cattle feed applications provides an advantage for regional AFEX processing centers and reduces the market risks associated with a single‐use application.…”