Characterization of light gluten and light steep water from a corn wet milling plant

The primary commodity of corn wet milling is starch, but two coproducts (corn gluten feed, CGF and corn gluten meal, CGM) also are produced. CGM and CGF are marketed as animal foodstuffs and are important economically; however, variation in composition reduces quality. There are few data on the effect of composition of the parent process streams, light steep water (LSW) and light gluten (LG), respectively, on composition of CGF and CGM. The objective was to characterize LG and LSW. Samples of LG and LSW were collected: (1) hourly for one day, (2) every 3 h for 3 days, and (3) daily for 3 weeks. Dry matter, N and ash were determined. Variation in composition of LG and LSW was greatest during longer periods of time (days and weeks) rather than shorter (hourly or every 3 h). There was significant variation in DM (solids) content, which directly affected the concentration of other components. Variation in N (protein) of LG and LSW accounted for much of the variation in CGF and CG. Processes that modify processing and reduce variation could increase the quality of CGF and CGM.     

Microfiltration of gluten processing streams from corn wet milling

In corn wet milling, dry matter can be separated from liquids in process streams with centrifuges or vacuum belt filtration (VBF). Because separations usually are not complete, dry matter can be lost in the liquid streams (overflow from the gluten thickener centrifuge and filtrate from VBF). This represents a loss of nutrients, especially protein, to low valued coproducts and reduces quality of water for recycling within the process. The objective was to compare microfiltration of light and heavy gluten process streams to conventional separation methods. Batches of light and heavy gluten were obtained from a wet mill plant and processed by microfiltration. Samples of permeate and concentrate from microfiltration were analyzed and compared to corresponding streams from wet milling. Microfiltration of light gluten resulted in concentrate and permeate streams similar in composition to conventionally processed light gluten using a centrifuge, suggesting that microfiltration is as effective as centrifugation in partitioning solids and water in light gluten. Dewatering of heavy gluten found that conventional VBF caused dry matter concentrations in gluten cake to be higher than concentrate from microfiltration. Permeate from microfiltration of heavy gluten had higher concentrations of ash and lower soluble nitrogen than filtrate from VBF. Microfiltration was able to remove more ash from concentrate, which may improve the value of wet milling coproducts. These data demonstrated microfiltration has potential for separation of light and heavy gluten streams, but more data are needed on effectiveness and practicality.     

Distribution of phosphorus compounds in corn processing

Distillers dried grains with solubles (DDGS) and corn gluten feed (CGF) are major coproducts of ethanol production from corn dry grind and wet milling facilities, respectively. These coproducts contain important nutrients, nevertheless, high levels of phosphorus (P). About 50-80% of the P in these products is in an organically bound form known as phytate. The phytate P in these products cannot be digested by nonruminant animals. Consequently, large quantities of phytate are deposited into the soil with the animal wastes which potentially could cause P pollution in soil and underground water resources. As regulations on the concentration of P material in ethanol production coproducts become more restrictive, measures need to be taken for effective extraction of phytate P from the coproducts to make these processes more environmentally compatible. Proper marketing of coproducts is critical to the overall economy of ethanol production facilities. In this study, distribution of P compounds in different streams of dry grind and wet milling operations was determined. In the dry grind process, the highest P concentration was found to be in the condensed distillers solubles (CDS) at about 1.34 wt.% (db). About 59% of P in this stream was in phosphates form. The highest concentration of P in the wet milling process was found in the light steep water at about 3.4 wt.% (db). In this stream, about 22% of P was attributed to phosphates.     

Membrane separation of solids from corn processing streams

Corn processing streams are characterized by high water content. Removal of water and recovery of solids are major economic and logistical challenges. New technologies are needed to modify processing streams and to reduce variability and improve quality of coproducts. The objective was to determine the effectiveness of microfiltration and ultrafiltration systems in altering water, solids (protein) and ash contents of corn processing streams. Corn was either steeped with SO(2) (STW) or soaked (SKW) in water; STW contained more solids than SKW. Ultrafiltration of STW and SKW had little effect on water removal or solids recovery. Corn was processed by a conventional wet milling process and a wet milling process that used enzymes to eliminate use of SO(2) steeping. Protein streams from the conventional process (CG) and the enzymatic process (EG) were processed by microfiltration. Permeate streams from EG and CG had higher total solids and ash concentrations than retentate streams; much of the ash was recovered in permeate (67% and 83%, respectively). For CG, proteins were largely recovered in retentate, whereas for EG, proteins were recovered in permeate. SDS-PAGE data indicated a decrease in size of proteins in the EG process stream. Permeate streams from microfiltration were subject to ultrafiltration; there was little effect on solids and nutrient separations.     

Nitrogen in vivo digestibility and in situ degradability data for estimation of lower tract N digestibility with or without correction for microbial contamination

In situ degradability and in vivo (by difference) digestibility trials were conducted to estimate lower tract residual N digestibility (LTRND) of five protein supplements. Efforts were also made to improve the in situ method of measuring protein degradability. For in situ degradability trials, soybean meal (SBM), corn gluten meal (CGM), cotton seed cake (CSC), wheat bran (WB) and corn gluten feed (CGF) were weighed into Dacron bags and incubated in the rumen of three cannulated Chios ewes. SBM, CGF and WB were degraded significantly, while CGM and CSC were least degraded. Microbial contamination (MC) resulted in a 5.3–28.3% artificially decrease in effective ruminal protein degradation of supplements. Total tract digestibility was measured using five rams in an in vivo, by difference, trial using a 5 × 5 Latin-square design. SBM had higher CP digestibility compared to WB, CGF and CSC, and higher N free extract (NFE) digestibility compared to the other feeds. CGM showed higher CP digestibility compared to WB, CGF or CSC, while CGF had higher organic matter (OM) and crude fibre (CF) digestibility compared to WB. CSC was the protein source with the lowest digestibility of OM, CP and NFE in comparison with the other feeds. LTRND was predicted as 0.928, 0.806, 0.227, 0.540, and 0.498 for SBM, CGM, CSC, WB, and CGF, respectively, or 0.931, 0.803, 0.147, 0.364, and 0.316 when the correction for MC was applied. Lower tract N digestibility could be predicted via a combination of in situ degradability and in vivo apparent digestibility data. This approach yields significant data regarding LTRND estimation of protein supplements, while diminishing animal suffering by avoiding small intestinal fistulation.     

Relationship between the amino acid release kinetics of feed proteins and nitrogen balance in finishing pigs

In current nutrition requirements of swine, although the protein diets are formulated based on the ileal digestibility of protein and amino acid (AA), there is a difference in nitrogen utilisation among various protein diets, which might be related to the AA release kinetics. To evaluate the relationship between AA release kinetics of feed proteins and nitrogen balance in finishing pigs, pigs were fed diets based on casein (CAS) or corn gluten meal (CGM) at normal or low-protein concentrations, and the AA release patterns were assessed. A 2 × 2 full factorial experimental design was used. 24 pigs (Duroc × Landrace × Yorkshire) with an initial weight of 67.0 ± 1.8 kg were randomly assigned to consume a normal-protein casein-based diet (N.CAS, 10% CP), normal-protein corn gluten meal-based diet (N.CGM, 10% CP), low-protein casein-based diet (L.CAS, 8.5% CP), or low-protein corn gluten meal-based diet (L.CGM, 8.5% CP) for 14 days (n = 6 per group; pigs housed and fed separately). The low-protein diets were associated with a more rapid release of AAs in the early stages of gastric digestion than the normal-protein diets. The N.CAS and L.CAS diets were associated with a peak AA release at approximately 4 h during trypsin digestion, whereas N.CGM and L.CGM were at approximately 16 h. The N.CAS diet was associated with the least dispersed release curves and lowest synchronisation indexes, implying that it was associated with the best AA release synchronism, whereas the L.CGM diet was on the contrary. The nitrogen intake (NI), faecal nitrogen, urine nitrogen (UN), total nitrogen, net protein utilisation and apparent biological value (ABV) of protein of pigs fed the L.CAS or L.CGM diets were lower than those fed the N.CAS or N.CGM diets (P < 0.05). Notably, there was a difference in NI (P < 0.05) and trends with respect to UN and ABV (0.05 < P < 0.1), but no differences in retained nitrogen or apparent nitrogen digestibility between pigs fed the N.CAS or L.CAS diets and those fed the N.CGM or L.CGM diets. Pigs fed the N.CAS or N.CGM diets had higher serum concentrations of UN than pigs fed the L.CAS or L.CGM diets (P < 0.05), but there were no differences in serum total protein, albumin, triglyceride, glucose, alanine transaminase, or aspartate aminotransferase between the groups. In addition, there was an interaction between protein level and protein source on serum globulin (P < 0.05). Therefore, the diet with a better AA release synchronism can improve protein utilisation efficiency in finishing pigs and to reduce environmental pollution.     

Dietary protein source affects lipid metabolism in the European seabass (Dicentrarchus labrax)

The study was undertaken to evaluate the effects of dietary protein sources on lipogenesis and fat deposition in a marine teleost, the European seabass (Dicentrarchus labrax). Four isonitrogenous (crude protein (CP, Nx6.25), 44% DM) and isoenergetic (22-23 kJ/g DM) diets were formulated to contain one of the following as the major protein source: fish meal (FM), one of two soy protein concentrates (SPC) and corn gluten meal (CGM). Apparent digestibility coefficients of the diets and raw ingredients, as well as soluble nitrogen (ammonia and urea) and phosphorus excretion were measured. Growth rates of seabass fed plant protein-based diets were significantly lower than those fed fish meal based diet. The protein utilisation was strongly correlated to the dietary essential amino acids index. Measurements of N excretion (ammonia and urea nitrogen) confirmed these data. Daily fat gain at the whole body level ranged between 1.1 to 1.7 g/kg BW, with the highest values being recorded in fish fed the fish meal based diet. Levels of plasma triglycerides and cholesterol were lower in fish fed soy protein diets than in those fed the diet solely based on fish meal. Soy protein rich diets decreased the activities of selected hepatic lipogenic enzymes (glucose 6-phosphate dehydrogenase, malic enzyme, ATP-citrate lysase, acetylcoenzyme A carboxylase and fatty acid synthetase). Highest lipogenic enzyme activities where found in fish fed the fish meal diet, except for fatty acid synthetase which was increased in seabass fed the corn-gluten meal based diets. Overall data suggest that dietary protein sources affects fat deposition and the lipogenic potential in European seabass.     

Significance of quality of truly digestible protein on performance of ewes at late pregnancy and early lactation

Two trials were conducted in ewes at late pregnancy and early lactation in order to evaluate the effects of substituting the moderate degradable protein of soy bean (SBM), with a low degradable protein of corn gluten meal (CGM), accordingly that both diets were calculated to provide equal truly digestible protein (PDI). At the first trial thirty multiparous ewes were examined in an 8-week study that started at parturition. Animals were fed in groups (15 ewes), with two isocaloric-isonitrogenous-isofibrous rations. Treatments were: (A) SBM, (B) CGM. Diets were different at PDIA/PDI ratio (0.52 versus 0.63). The second trial lasted 7 weeks, 5 weeks pre partum till 2 weeks post partum. Three rations were tested by the use of 48 pregnant ewes. Ewes were allotted to three equivalent groups: (A) SBM and wheat bran, (B) CGM and corn gluten feed, (C) CGM and corn gluten feed plus additional lysine (CGML). Data from both trials were analyzed as repeated measures. CGM compared to SBM decreased milk yield and fat corrected milk (FCM) yield (2.25 and 1.98 kg of milk; 2.47 and 2.17 kg of FCM), while tended to decrease milk's protein content (5.45 and 5.36%, for the SBM and CGM group). The daily production of fat, protein and lactose were higher in SBM than in CGM. CGM ration decreased body weight (BW) gain of ewes during late pregnancy and mean birth BW of litter, and also caused a 30% increase of abortions-dead births. CGM cannot totally replace SBM, in ewes’ diets at early lactation, because of the decrease in milk yield as well as the milk's protein content, even when equal PDI is provided, due to low lysine content. This trial has extended the knowledge from cattle, that supplementation of lysine, usually the first limiting amino acid, is also crucial in ewes during pregnancy and lactation.     

Composition of corn and distillers dried grains with solubles from dry grind ethanol processing

Increase in the demand for ethanol has resulted in growth in the dry grind (DG) ethanol industry. In DG processing, the whole corn kernel is fermented, resulting in two main coproducts, ethanol and distillers dried grains with solubles (DDGS). Marketing of DDGS is critical to the economic stability of DG plants. The composition of DDGS can vary considerably; this reduces market value. Factors that cause variation in composition need to be evaluated. The objective was to determine the relationship between composition of corn and composition of DDGS. Samples of corn and DDGS were obtained from a DG ethanol plant and analyzed for protein, fat, starch and other nutrients. Concentrations of protein, fiber and starch were similar to published data for corn but were higher for DDGS. Coefficients of variation for protein fat and fiber concentrations were similar for corn and DDGS. There were no significant correlations between concentrations of components in corn and those in DDGS. Variation in the composition of DDGS was not related to variation in corn composition and probably was due to variation in processing streams or processing techniques. This implies that reducing the variation in composition of DDG will require modification of processing strategies.     

Digestibility of phosphorous in cereals and co-products for animal feed

Feed ingredients used in swine diets contain various levels and availabilities of nutrients. Nutritional precision evaluation of each ingredient is necessary for formulating diets of pigs. Especially, phosphorous (P) is one of important nutrients for metabolism. However, current data of P digestibility were most apparent digestibility. Therefore, this study was aimed to estimate the coefficient of total tract standardized digestibility (CTTSD) of P in cereals and various co-products used in pig diet. Twelve barrows (initial BW?±?SD, 46.70?±?3.21?kg) were used in this experiment. The experimental design was a 12?×?8 incomplete Latin square with 12 diets and 8 periods. Experimental diets were consisted of barley, wheat, lupine kernel (LK), soybean meal (SBM), almond meal (AM), corn gluten meal (CGM), corn gluten feed from China (CGF-C), corn gluten feed from Korea (CGF-C), wheat bran (WB), rice bran (RB), lupine hull (LH) and P-free diet. The CTTAD of Ca was higher in AM than RB and CGF-K. The LK and CGM showed greater CTTSD of P than RB and LH. In conclusion, our results indicated that the cereals and co-products as P sources were the ideally used as an ingredient in mixed diets of the growing-finishing pigs.     

Nutritional value of 15 corn gluten meals for growing pigs: chemical composition, energy content and amino acid digestibility

The objectives of this study were to determine the chemical composition, energy content and amino acid digestibility for corn gluten meals (CGM) and to develop prediction equations for estimating energy content and amino acid digestibility for growing pigs based on the chemical characteristics of these meals. The 15 CGM tested were obtained from seven Chinese companies. Experiment 1 was conducted to determine the digestible (DE) and metabolisable energy (ME) of the 15 CGM. The 18 growing barrows (38 +/- 4 kg) were assigned to three 6 x 6 Latin square designs. The 15 CGM test diets were formulated to contain 19.20% CGM, which replaced 20% of the energy supplied by corn and crystalline amino acid in the basal diet. Experiment 2 was conducted to determine the apparent (AID) and standardised (SID) ileal digestibility of the crude protein (CP) and amino acids in the 15 CGM using chromic oxide as an inert marker. The 18 growing barrows (25 +/- 2 kg) fitted with a simple T-cannula were assigned to three 6 x 6 Latin square designs. The 15 test diets contained 35% of one of the 15 CGM as the sole source of amino acids in the diet. The results showed a considerable variation in the chemical composition of CGM within and among plants. On dry matter basis, the DE and ME content of the CGM ranged from 18.8 to 21.0 MJ/kg and from 18.0 to 19.9 MJ/kg, respectively. There were no significant differences in the AID and SID for CP, arginine, lysine, glycine and proline among the 15 CGM, however, for all the other amino acids, significant differences were found for their AID and SID. With R2 values exceeding 0.50, the DE of CGM can be predicted accurately from CP and fibre content and ME from starch and fibre content. Suitable prediction equations for SID of methionine were also developed.     

Plant products affect growth and digestive efficiency of cultured Florida pompano (Trachinotus carolinus) fed compounded diets

Costs of compounded diets containing fish meal as a primary protein source can be expected to rise as fish meal prices increase in response to static supply and growing demand. Alternatives to fish meal are needed to reduce production costs in many aquaculture enterprises. Some plant proteins are potential replacements for fish meal because of their amino acid composition, lower cost and wide availability. In this study, we measured utilization of soybean meal (SBM) and soy protein concentrate (SPC) by Florida pompano fed compounded diets, to determine the efficacy of these products as fish meal replacements. We also calculated apparent digestibility coefficients (ADCs) for canola meal (CM), corn gluten meal (CGM), and distillers dried grains with solubles (DDGS), following typical methods for digestibility trials. Juvenile Florida pompano were fed fish-meal-free diets containing graded levels of SBM and SPC, and weight gain was compared to a control diet that contained SBM, SPC, and fish meal. Fish fed diets that contained 25-30 percent SBM in combination with 43-39 percent SPC had weight gain equivalent to fish fed the control diet with fish meal, while weight gain of fish fed other soy combinations was significantly less than that of the control group. Apparent crude protein digestibility of CGM was significantly higher than that of DDGS but not significantly different from CM. Apparent energy digestibility of DDGS was significantly lower than CGM but significantly higher than CM. Findings suggested that composition of the reference diet used in a digestibility trial affects the values of calculated ADCs, in addition to the chemical and physical attributes of the test ingredient.     

Microscopic analysis of corn fiber using starch- and cellulose-specific molecular probes

Ethanol is the primary liquid transportation fuel produced from renewable feedstocks in the United States today. The majority of corn grain, the primary feedstock for ethanol production, has been historically processed in wet mills yielding products such as gluten feed, gluten meal, starch, and germ. Starch extracted from the grain is used to produce ethanol in saccharification and fermentation steps; however the extraction of starch is not 100% efficient. To better understand starch extraction during the wet milling process, we have developed fluorescent probes that can be used to visually localize starch and cellulose in samples using confocal microscopy. These probes are based on the binding specificities of two types of carbohydrate binding modules (CBMs), which are small substrate-specific protein domains derived from carbohydrate degrading enzymes. CBMs were fused, using molecular cloning techniques, to a green fluorescent protein (GFP) or to the red fluorescent protein DsRed (RFP). Using these engineered probes, we found that the binding of the starch-specific probe correlates with starch content in corn fiber samples. We also demonstrate that there is starch internally localized in the endosperm that may contribute to the high starch content in corn fiber. We also surprisingly found that the cellulose-specific probe did not bind to most corn fiber samples, but only to corn fiber that had been hydrolyzed using a thermochemical process that removes the residual starch and much of the hemicellulose. Our findings should be of interest to those working to increase the efficiency of the corn grain to ethanol process.     

Evaluation of corn gluten meal with urea as a source of supplementary nitrogen for growing calves and lambs

Three growth trials and a metabolism study were conducted to evaluate corn gluten meal—urea (CGM—urea) combinations compared to a urea control as sources of supplementary nitrogen for growing calves and lambs fed on diets based on corn cobs.In the first growth study cattle were fed individually twice daily while in the sheep growth study and the second cattle growth study, animals were fed in groups. The average daily gain and feed conversion were similar for animals given the soya bean meal (SBM) and CGM—urea supplements. Feed intakes were similar for all treatments except for growth study 1. Nitrogen retention and dry matter and protein digestibility did not differ significantly between the SBM and CGM—urea supplemented groups. Urea consistently gave inferior results in all the experiments. These results suggest that CGM—urea combination is essentially equal to SBM in supporting growth of calves and lambs.     

Nutritional value of 15 corn gluten meals for growing pigs: chemical composition,energy content and amino acid digestibility

The objectives of this study were to determine the chemical composition, energy content and amino acid digestibility for corn gluten meals (CGM) and to develop prediction equations for estimating energy content and amino acid digestibility for growing pigs based on the chemical characteristics of these meals. The 15 CGM tested were obtained from seven Chinese companies. Experiment 1 was conducted to determine the digestible (DE) and metabolisable energy (ME) of the 15 CGM. The 18 growing barrows (38 ± 4 kg) were assigned to three 6 × 6 Latin square designs. The 15 CGM test diets were formulated to contain 19.20% CGM, which replaced 20% of the energy supplied by corn and crystalline amino acid in the basal diet. Experiment 2 was conducted to determine the apparent (AID) and standardised (SID) ileal digestibility of the crude protein (CP) and amino acids in the 15 CGM using chromic oxide as an inert marker. The 18 growing barrows (25 ± 2 kg) fitted with a simple T-cannula were assigned to three 6 × 6 Latin square designs. The 15 test diets contained 35% of one of the 15 CGM as the sole source of amino acids in the diet. The results showed a considerable variation in the chemical composition of CGM within and among plants. On dry matter basis, the DE and ME content of the CGM ranged from 18.8 to 21.0 MJ/kg and from 18.0 to 19.9 MJ/kg, respectively. There were no significant differences in the AID and SID for CP, arginine, lysine, glycine and proline among the 15 CGM, however, for all the other amino acids, significant differences were found for their AID and SID. With R ² values exceeding 0.50, the DE of CGM can be predicted accurately from CP and fibre content and ME from starch and fibre content. Suitable prediction equations for SID of methionine were also developed.     

Changes in mineral concentrations and phosphorus profile during dry-grind processing of corn into ethanol

For determining variation in mineral composition and phosphorus (P) profile among streams of dry-grind ethanol production, samples of ground corn, intermediate streams, and distillers dried grains with solubles (DDGS) were obtained from three commercial plants. Most attributes (dry matter concentrations) increased significantly from corn to cooked slurry but fermentation caused most significant increase in all attributes. During centrifugation, more minerals went into thin stillage than wet grains, making minerals most concentrated in the former. Mineral increase in DDGS over corn was about 3 fold, except for Na, S, Ca, and Fe. The first three had much higher fold of increase, presumably due to exogenous addition. During fermentation, phytate P and inorganic P had 2.54 and 10.37 fold of increase over corn, respectively, while relative to total P, % phytate P decreased and % inorganic P increased significantly. These observations suggest that phytate underwent some degradation, presumably due to activity of yeast phytase.     

Digestibility of fractionated green biomass as protein source for monogastric animals

Globally, there is an increased demand for sustainable protein sources for animal feed. Grass and forage legumes have the yield potential to become such alternatives, but the protein needs to be separated from the fibres. Red clover, white clover, lucerne and perennial ryegrass were fractionated into a green juice and a fibrous pulp in a screw-press and protein was subsequently precipitated. The nitrogen (N) and amino acid composition of the produced fractions was analysed and the digestibility of dry matter (DM) and N was evaluated using a rat digestibility trial. The aim was to determine the effect of fractionation on composition and digestibility in order to evaluate the four plants as potential protein sources for monogastrics. Protein concentrates with CP concentrations of 240 to 388 g/kg DM and fibrous pulps with CP concentrations of 111 to 216 g/kg DM were produced. The sum of all analysed amino acids was highest in the protein concentrates corresponding to a low concentration of non-protein nitrogen ranging from 4.9% to 10.4%. Only small variations were seen in the amino acid compositions of the different plants and fractions. The concentration of the essential lysine and methionine in the protein concentrate ranged from 6.27 to 6.67 g/16 g N and 1.54 to 2.09 g/16 g N for lysine and methionine, respectively. For all plants species, total tract digestibility of DM and standardised N digestibility was significantly higher in the protein concentrates (60.8% to 76.5% and 75.4% to 85.0% for DM and N, respectively) compared to pulp (21.2% to 43.4% and 52.1% to 72.5% for DM and N, respectively). Digestibility of lucerne protein concentrate (76.5% and 85.0% for DM and N, respectively) was higher than of the unprocessed plant (39.6% and 74.9% for DM and N, respectively), whereas for red and white clover no difference was found. The amino acids methionine and cysteine were limiting for pigs and broilers in all fractions regardless of plant origin, and low scores were also found for lysine. The study demonstrated great potential of using green plants as a protein source for monogastrics because of high protein content, balanced amino acid composition and high digestibility of DM and N. The effects of processing and protein precipitation were pronounced in lucerne where significantly improved digestibility was observed in the protein concentrate. The results from the study provide valuable and enhanced knowledge to the production of alternative and sustainable protein sources for monogastric feed.     

氮磷钾硫对冬小麦产量及加工品质的调节效应

试验在中国农业科学院作物科学研究所试验基地进行,以强筋小麦品种为试验材料,研究不同氮磷钾硫肥料处理对小麦产量和品质的影响.结果表明,在高产的条件下以120kg/hm2施氮的处理,产量、千粒重和容重最高,过度施氮使产量、千粒重和容重呈逐渐降低的趋势,子粒硬度随施氮量增加而提高.蛋白质含量、湿面筋含量、形成时间和稳定时间均有随施氮量增加而提高的趋势,增加施氮量显著增加了面包体积.蛋白质含量、湿面筋含量和稳定时间有随施钾量增加而提高的趋势.施磷和硫处理对产量和品质的影响不显著.     

麦瑞加拉鲮幼鱼对12种原料表观消化率的比较研究

试验以麦瑞加拉鲮（Cirrhinus mrigala）幼鱼（3.88±0.06）g为试验对象,研究其对国产鱼粉、白鱼粉、花生粕、白酒糟、鸡肉粉、米糠、棉粕、菜粕、豆粕、玉米蛋白粉、玉米酒糟和羽毛粉的干物质、粗蛋白、粗脂肪、总能、磷、钙、镁、锌、铜、铁和锰的表观消化率。结果表明:12种试验原料的干物质、粗蛋白质、粗脂肪、总能、磷、钙、镁、锌、铜、铁和锰的表观消化率范围分别为24.93%-85.68%、50.02%-97.40%、51.89%-94.02%、39.18%-96.39%、9.72%-87.37%、3.47%-25.92%、26.11%-88.25%、12.63%-66.35%、41.33%-104.86%、10.69%-91.84%、4.42%-85.49%。其中包括干物质、粗蛋白和总能在内的主要营养物质的表观消化率以国产鱼粉和白鱼粉最高。除鱼粉外的其他原料中,干物质以花生粕、豆粕和玉米蛋白粉最高;粗蛋白以花生粕最高;粗脂肪以米糠和花生粕最高;总能以花生粕和鸡肉粉最高;白酒糟的干物质、粗蛋白、粗脂肪、总能的消化率最低。在矿物质元素表观消化率中,羽毛粉的磷、铜、铁和锰的表观消化率最高;米糠的锌表观消化率最高;钙的表观消化率以白鱼粉、豆粕和羽毛粉最高;镁的表观消化率以豆粕、羽毛粉和玉米酒糟最高;鸡肉粉的磷、钙、镁和铁表观消化率最低;花生粕和棉粕中锌的表观消化率最低;菜粕中铜的表观消化率最低;白酒糟中锰的表观消化率最低。因此,花生粕、豆粕和玉米蛋白粉是麦瑞加拉鲮幼鱼配合饲料中较优质的蛋白源,可进一步开发用于适量替代饲料中的鱼粉;米糠可作为较好的能量饲料;羽毛粉可作为饲料中较好的矿物质元素来源;白酒糟对麦瑞加拉鲮幼鱼而言营养价值最差。