The energy content of sorghum as affected by enzymatic or physical treatment

Three chicks experiments were conducted for a period of 14 days each to evaluate nitrogen retention, body weight gain, feed consumption and metabolizable energy (ME) of various grain sorghum samples. Approximately equal dietary grain levels were supplied by various grain sorghum samples. Differences in ME values were found when grains were fed with or without a commercial enzyme, and when grains were fed with or without physical process of rolling or steaming and rolling. It was found that, with the enzyme added, ME increased by 1 to 5%, while in another case with the same enzyme ME decreased by 1 to 11%. When the grain sorghum was fed rolled it was found to result in an increase of 10%. Furthermore, when the same grain was fed after steaming and rolling, a decrease of 1% was observed in ME content. REVIEW OF LITERATURE Two experiments were run by Alejar, Ranit and Manese (1969), with the purpose of finding out if grain sorghum could partially or totally replace corn as a source of ener­ gy in the broiler ration. Their results showed no adverse effect on either gain, feed efficiency, or mortality of broilers when high levels of sorghum were fed. The rations containing sorghum proved to be practical and profitable. In another experiment by Petersen (1969) using broilers, he found very good values for sorghum (with low tannin content), comparing it with corn, barley, wheat and oats. While find­ ing only the corn to be superior to the sorghum in the abil­ ity to promote growth. Grains were highly correlated with the energy intake, but not with the calculated ME per kg of the diet. Hill et al. (I960) evaluated the metabolizable energy (ME) of grain and grain products with chickens and found among the 21 values determined an ME value for sorghum of 1,480 kcal per pound. In a work by Fry et al. (1958) they found that en­ zyme supplementation or water treatment improved the ME of barley, rye or wheat significantly for turkey poult growth. They further demonstrated that other treatments such as autoelaving or drying of pearled barley (before or after water treatment) did not improve either growth or feed effi­ ciency. Moran and McGinnis (1965) conducted an experiment to determine the effect of enzyme and antibiotic supplemen­ tation on the growth of turkey poults fed diets containing either corn or barley as the cereal grain. No effect was observed for corn in relation to growth, unless the protein to energy relationship was extensively altered. Diets con­ taining barley showed a good response to the enzyme or anti­ biotic supplementation. In another study Moran, Lall and Summers (1969) found that changing the physical form of the ration from mash to crumbles resulted in significant im­ provements in both live performance and whole diet metabo­ lizable energy when the birds were fed rye, but this was not true for corn based diets. Using only crumbled rations, growth responses due to supplementation with either a mix­ ture of antibiotics and/or crude enzyme concentrates of bac­ terial fungal origin varied from experiment to experiment, but resulted in consistent though small improvements with rye but not with corn. Weber (1975) fed grains to broiler chicks with or without an enzyme which was added to either wheat, triticale or barley and attempted to increase the ME values of the grains. The results showed increased ME ■ values for all grains with some degree of variability among similar varieties of grain. The commercial enzyme used was Nopgro from The Diamond Shamrock Co. The Diamond Shamrock Co. stated that the enzyme promotes growth, improves feed efficiency and increases egg production in poultry when added at levels as low as 0.1 to 0.3% of the feed, with best results obtained When rations contained high levels of either barley, wheat by-products or other fibrous feedstuffs. Praga Fernandez-Cuevas and Galvez Morros (1971) studied the effects of adding a proteolytic enzyme to the feed of laying hens. Their experiment, was run using sixty ' white leghorn hens of an average age of 238 days, and for a period of 72 days. Ten groups were fed as follows: 1 was the control; 3 were given pepsin prepared from pig stomach at 10 mg, 100 mg or 1 gm/kg of feed; 3 were given papain at 10 mg, 100 mg, or 1 gm/kg of feed; and 3 were given both pepsin and papain, 10 mg of each, 100 mg or each or 0.5 gm of each per kg of feed in diets using 60% corn. The results showed greater numbers of eggs produced and increased egg weights in the groups fed the enzyme supplements. According to Far!in (1976), in cattle milo is great­ ly improved when it is processed by any physical method such as fine or coarse grinding, steam rolling, pelleting and steam flaking. He found improvements as high as 9% as' a result of such processing. Boldaji (1969) found that ME values of grain sorghum were improved by 4 to 8% after steam cooking and 8 to 15% after pressure cooking at 50 to 80 lb per sq inch. This latter method of processing produced sorghum equal -to corn for egg production and feed conversion. Furthermore, metab­ olizable energy and protein quality differed among varieties of sorghum. Kojima et al. (1968) studied the effect of cooking on barley and sorghum, which was then mixed in the ration for digestibility determinations. They used 6 weath­ ers and they found reduced digestibility of the protein, ether extract and fiber in both grains as a result of the cooking process. Weber (1970) found that treating sorghum by steaming and flaking increased egg production and im­ proved feed conversion. The data suggested a further in­ crease in egg production being derived from flaking over the effect of steaming only. Weber (1971) in a further study found that no beneficial effect was derived ;from either the flaking or steaming of sorghum. From the standpoint of economics, the mechanical processing of sorghum for use in poultry feed is highly questionable, because of the high costs of equipment for processing. The purpose of this study is to find out if the ME values of sorghum in chick diets can be increased by the use of an enzyme preparation (Nopgro) and/or physical processing of the grain. EXPERIMENTAL PROCEDURE Three experiments with chicks were conducted at The .University of Arizona Poultry Research Center during the course of this work. The purpose of these experiments was to study the effects of an enzyme and/or physical processing on the me­ tabolizable energy values of sorghum for young chicks. Criteria used were: body weight gains feed consumption, nitrogen retention and metabolizable energy determinations. Grain sorghum was used in these studies. Grain sorghum sam/ • 1 pies were fed untreated, treated with enzyme, steamed and rolled, and steamed and rolled with enzyme. The steamed and. rolled grain sorghum samples were prepared at The University of Arizona Animal Science Farm, while some of the sorghum samples were rolled in Mexico. Chromic oxide was added to all diets at a level of 0.2% as a trace marker for digest­ ibility determinations (Edwards and Gillis 1959)• The chicks were provided with feed and water ad libitum. Sexed Hubbard broiler chicks were randomly distributed among the pens in a battery brooder with a raised screen floor. There were two replicates in each treatment and each replicate con­ tained six chicks (3 males and 3 females). All experiments were, carried out for a period of 14 days. ' ■ ■ 6 In the three experiments sorghum grains used were as follows: Asgrow TXS Pioneer 820s commercial sorghum of un­ known varietys commercial sorghum acquired from Mexico, and commercial sorghum of unknown variety acquired from the Ani­ mal Science Department. For each experiment a semipurified basal diet' was formulated by digital computer to meet the essential nutri­ ent requirements according to the recommendations of the National Research Council (1971) when mixed with the grain studied (Tables 1, 2, 3 and 4). Each basal diet was mixed with sorghum at two levels as indicated in each experiment; thus, the experimental diets supplied two different intakes of protein and energy in relation to the level of grain fed. In each case the birds and the feed were weighed initially and upon termination of trie experiment; unconsumed feed was weighed in order to determine feed consumption. Fecal samples were collected during the 4th week and both feed and feces were analyzed for total nitrogen, chro­ mic oxide (CrgOg), and gross energy. Nitrogen retention values were calculated from the values of chromic oxide in the feeds and feces using the method of Edwards and Gillis (1959). The ground excreta and feed samples were then ana­ lyzed for gross energy using a Parr Oxygen Bomb Calorimeter, and nitrogen was determined by the Kjeldahl method (Official