Biofuel co-products as livestock feed - Opportunities and challenges

294Biofuel co-products as livestock feed – Opportunities and challengesdegradation or loss of carbohydrate, (3) avoid formationof products inhibitory to the subsequent hydrolysis andfermentation processes, (4) improve palatability, and (5) becost-effective (Ye and Cheng, 2002).Steam treatmentMajor reasons for using steam as pre-treatment for improvingthe nutritive value of bagasse is the ready availabilityof steam at sugar plants, which could be easily used withminimum investment and, as it does not involve use of anychemicals, it is likely to be safe. The steam pressure treatmentcompletely modifies the hemicellulose fraction ofraw bagasse, changing it into more soluble components,but does not affect the ligno cellulose components (Wonget al., 1974; Pate, 1982; Kling et al., 1987). Replacementof maize silage with equal proportions of cubed hay andbagasse (steamed and pelleted with wood chips) resultedin similar energy intake, milk yield and protein content, butlowered milk fat and total solids in a bagasse-fed group ofmilch animals (Sekiguchi et al., 1981). Steam treatment ofbagasse was found to improve its digestibility and acceptabilityto animals due to changes in colour, smell and palatability(Rangnekar et al., 1982, 1986). Rumen dry matterdegradability in Zebu cattle determined by the nylon bagtechnique for untreated, steam ammoniated (NH 3 ; 3%) andsteamed bagasse was found to be 17, 20 and 31 percentagainst 35 percent in the control that contained cottonwool (de la Cruz, 1990). Heat treatment in the presenceof water (solvolysis) or aqueous orthophosphoric acid at2.9 percent w/w (phosphorolysis) was also used to increasethe nutritional value of sugar cane bagasse for cattle feeding(Fontana, Ramos and Deschamps, 1995).Steaming of fresh bagasse at a pressure of 15 kg/cm 2for 10 minutes and fed at 50 percent of dietary dry matterin wethers resulted in improved digestibility and wasfound equivalent to wild grass. The estimated total digestiblenutrients (TDN) value of steam-treated bagasse was48.7 percent (Tanabe and Kume, 2004). Ammonia pressurizationat 1 g/g of bagasse in a reactor in liquid phasefor 5 minutes at 50 percent bagasse moisture resulted inmaximum solubulization of ligno cellulosic contents, leadingto enhanced value of bagasse as feed substrate in animals(Pernalete et al., 2008). Steam-treated bagasse pith couldreplace 30 percent of the concentrate component of thediet (15 percent of total diet) without any negative effecton physiological and productivity parameters (body weightchanges in ewes and lambs, milk composition, bloodparameters) in pre- and post-lambing Lorie ewes, over aperiod of 120 days (Ebrahimi et al., 2009).Alkali or acid treatmentAlkali or acid treatment of ligno cellulosic material has beenquite widely used by different workers to improve the nutritivevalue of fibrous feed stuff. Ensiling of green sorghumalone or with 20 percent wheat straw and poultry litter,or 20 percent bagasse with poultry litter, resulted in comparabledry matter, protein and fat digestibility betweenthe animal groups fed three types of ensiled diets. Thedigestible crude protein (DCP) and TDN of sorghum silage,wheat straw and bagasse-added groups were 2.0, 60.1;4.3, 45.3; and 6.1, 50.3 percent, respectively (Parthasarathyand Pradhan, 1982). Tudor and Inkerman (1986) reportedan increase in organic matter digestibility in vitro from28 to 63 percent in sugar cane bagasse with increasingconcentrations of NaOH. Supplementation of black liquor,an effluent containing NaOH (10.5 g/litre) from thepaper industry to bago-molasses and ensiling for 90 days(bagasse:molasses mixed in a 10:1 ratio and DM adjustedto 70%) resulted in higher digestibility of ligno cellulosicmaterials in male buffalo calves (Prasad and Prasad, 1986).Nour and El-Tourky (1987) reported that treatment ofbagasse or sugar cane pith with 5 percent NaOH and supplementedwith cottonseed cake resulted in improvementin the intake and digestibility of nutrients, and better nutritivevalue of diets in Rahmany rams, compared with thosefed untreated bagasse. Further, the productive performanceof animals fed a pith-containing diet was better thanbagasse-containing diets.The response in Holstein bulls fed corn brewers grainbagassesilage with alfalfa pellets versus concentrate withalfalfa pellets resulted in comparable growth rates, nutrientdigestibility and carcass traits with economic advantage inbagasse-fed groups. However, there were differences in theblood parameters (Su and Yan, 1998a). The use of distillerscorn brewers grain-bagasse silage with alfalfa pellets versusconcentrate with alfalfa pellets in crossbred goats resultedin similar weight gains, nutrient digestibility, blood parametersand carcass traits, with economic advantage in thebagasse-fed group (Su and Yan, 1998b). The feed intake,digestibility of nutrients, carcass characteristics and bloodparameters did not differ between the groups of yellowcattle fed either distillers rice grain with bagasse silage andconcentrate or Pongola grass silage and concentrate, withthe feed cost per kg of liveweight gain was more economicin the bagasse-based silage-fed group (Su and Yan, 2000).Odai et al. (2002) reported that bagasse silage can be keptfor at least 90 days and then used as a source of roughagefor dairy cattle during the dry season. A combination of25 percent each of bagasse and rice straw and 50 percentbrewer’s grains can be used for fattening beef cattle. Yongand Zhou (2002) reported that treatment of bagasse with 5or 7 percent hydrogen peroxide, urea + Ca(OH) 2 , or Urea +NaOH increased the degradation rate and fibre degradationindex, while the treatment with urea alone could not achievethe same effect. Calcium hydroxide treatment at 8 percentof bagasse dry matter decreased the contents of NDF, ADF