Dual potential of microalgae as a sustainable biofuel feedstock and animal feed

The rise in global population has led to explorations of alternative sources of energy and food. Because corn and soybean are staple food crops for humans, their common use as the main source of dietary energy and protein for food-producing animals directly competes with their allocation for human consumption. Alternatively, de-fatted marine microalgal biomass generated from the potential biofuel production may be a viable replacement of corn and soybean meal due to their high levels of protein, relatively well-balanced amino acid profiles, and rich contents of minerals and vitamins, along with unique bioactive compounds. Although the full-fatted (intact) microalgae represent the main source of omega-3 (n-3) polyunsaturated fatty acids including docohexaenoic acid (DHA) and eicosapentaenoic acid (EPA), the de-fatted microalgal biomass may still contain good amounts of these components for enriching DHA/EPA in eggs, meats, and milk. This review is written to highlight the necessity and potential of using the de-fatted microalgal biomass as a new generation of animal feed in helping address the global energy, food, and environmental issues. Nutritional feasibility and limitation of the biomass as the new feed ingredient for simple-stomached species are elaborated. Potential applications of the biomass for generating value-added animal products are also explored.     

银合欢、木薯饲料的研发及应用效果

随着畜牧业的蓬勃发展,畜禽及水产饲料产量逐年增长,致使饲料原料短缺,除蛋白质饲料不足外,能量饲料不足的问题也越来越严重,开发廉价的饲料资源替代部分玉米和大豆等能量与蛋白质原料势在必行。银合欢和木薯因其自身的优势在饲料应用上有着巨大的潜力,但也存在不少缺陷,再加上对其饲料研发技术不够成熟,目前仍不能很好的发挥其作用。作者针对其良好应用效果、饲料应用潜力及研发技术处理作一简述,为研究利用中国热带地区产量高、营养丰富的银合欢和木薯提供一定的参考,有望作为替代部分玉米和大豆等能量与蛋白质的重要原料。     

Replacing fish oil and astaxanthin by microalgal sources produced different metabolic responses in juvenile rainbow trout fed 2 types of practical diets

Dietary fish oil supplementation provides n-3 long-chained polyunsaturated fatty acids for supporting fish growth and metabolism and enriching fillet with eicosapentaenoic acid (EPA; 20:5n-3) and docosahexaenoic acid (DHA; c22:6n-3). Two experiments were performed as a 3 × 2 factorial arrangement of dietary treatments for 16 wk to determine effects and mechanisms of replacing 0%, 50%, and 100% fish oil with DHA-rich microalgae in combination with synthetic vs. microalgal source of astaxanthin in plant protein meal (PM)- or fishmeal (FM)- based diets for juvenile rainbow trout (Oncorhynchus mykiss). Fish (22 ± 0.26 g) were stocked at 17/tank and 3 tanks/diet. The 100% fish oil replacement impaired (P < 0.0001) growth performance, dietary protein and energy utilization, body indices, and tissue accumulation of DHA and EPA in both diet series. The impairments were associated (P < 0.05) with upregulation of hepatic gene expression related to growth (ghr1and igf1) and biosynthesis of DHA and EPA (fads6 and evol5) that was more dramatic in the FM than PM diet-fed fish, and more pronounced on tissue EPA than DHA concentrations. The source of astaxanthin exerted interaction effects with the fish oil replacement on several measures including muscle total cholesterol concentrations. In conclusion, replacing fish oil by the DHA-rich microalgae produced more negative metabolic responses than the substitution of synthetic astaxanthin by the microalgal source in juvenile rainbow trout fed 2 types of practical diets.     

两型饲料的能量和新型蛋白质替代原料

两型饲料是指资源节约型和环境友好型饲料。目前,市场上猪、肉鸡和蛋鸡的日粮以玉米豆粕型为主,需要新的解决方案来改善饲料生产可持续性和解决工农争粮问题。有许多原料可作为替代能量和蛋白质来源正受到人们的关注,其中包括高粱、大麦、昆虫源性原料、藻源性蛋白和单细胞蛋白等。文章主要论述了两型饲料中纤维的重要性以及几种能量和新型蛋白质替代猪只饲料原料的应用前景。     

Effect of dietary defatted diatom biomass on egg production and quality of laying hens

Background： This study was to determine if feeding laying hens with defatted diatom microalgal biomass （DFA） from biofuel production affected their egg production and health status. Methods： Five replicates of 5 individually caged ISA Babcock White leghorn hens were fed 4 diets, including a corn-soybean meal control diet, a diet containing 7.5% DFA substituting for soybean meal, and diets containing 7.5% or 15% DFA substituting for corn and soybean meal. Body weights, feed intake, feed conversion ratio （FCR）, rate of egg production, egg size, egg mass, and several characteristics of eggs were determined at 4 and 8 wk. Venous blood was sampled at 4 and 8 wk for measurement of 5 biomarkers of health. Results： The15% DFA diet decreased （P 〈 0.05） feed intake, egg production, and plasma uric acid concentrations as compared with the control diet, but increased （P 〈 0.05） egg albumen weight and height compared with the 7.5% DFA diets. The two levels of DFA produced dose-dependent （P 〈 0.05） changes in three color measures of egg yolk, without affecting four hen plasma biochemical indicators of health. Conclusions： Feeding laying hens with 7.5% DFA in the corn-soybean meal diet for 8 wk had no adverse effect on their health, egg production, or egg quality, but 15% inclusion reduced feed intake, egg production, and efficiency of feed utilization.     

Nutritional value of quality protein maize and food corn for starter and growth pigs

Growth traits with starter and grower pigs and a digestion trial were conducted to compare the nutritional value of Quality Protein Maize (QPM), food corn and conventional feed corn. The QPM, food and feed corn contained .45, .31 and .29% lysine, respectively. The growth trials evaluated a QPM-soybean meal diet formulated on a lysine basis (.96% in starter and .7% in grower diets) and four diets arranged in a 2 (food corn vs feed corn) X 2 (low vs high soybean meal) factorial. Soybean meal was either added in the same amount as in the QPM diet or was added to provide the lysine content of the QPM diet. Performance was similar for pigs fed food corn and feed corn in both trials. The QPM diets resulted in greater performance than food and feed corn diets containing the same level of soybean meal supplementation; starter pigs were more (P less than .10) efficient and grower pigs had a higher (P less than .01) rate and efficiency of gain. However, performance of pigs fed the QPM diets was not equal to that of pigs fed isolysinic food and feed corn diets; growth rate was lower (P less than .05) in starter pigs and gain:feed was lower (P less than .05) in grower pigs. Diets in the digestion trial consisted of the corns plus 3.25% casein. Energy digestibility was similar for all diets. Ileal N and amino acid digestibilities were highest for QPM, intermediate for food corn and lowest for feed corn. In most instances, these differences were significant (P less than .05). Apparent biological value was highest (P less than .05) for QPM. These trials indicate that food corn and feed corn have similar nutritional value, and that starter and grower pigs can benefit from the higher protein quality of QPM.     

Effects of forage and protein source on feedlot performance and carcass traits of Holstein and crossbred beef steers.

Fifty-eight Holstein and 58 crossbred beef steers were individually fed one of four isonitrogenous diets to evaluate the effects of forage source (corn silage and alfalfa haylage) and protein source (soybean meal and fish meal) on feedlot performance. Phase 1 diets (up to 354 kg of BW) were 40% forage and 60% concentrates and were fed for 70 to 136 d (depending on diet and breed group). Phase 2 diets (354 kg of BW until slaughter) were 20% forage and 80% concentrates and were fed for 127 to 150 d (depending on diet and breed group). Slaughter end points were .6 cm of 12th rib fat for Holsteins and 1.0 cm of rib fat for crossbreds using real-time ultrasonic estimates. The steers were fed for a maximum of 330 d each year. Forage source was a significant component of variation for most growth, efficiency, and carcass traits. Holstein and crossbred steers fed alfalfa haylage had significantly lower average daily gain, feed efficiency, dressing percentage, and empty body fat and required more days on feed to reach slaughter end points, but had higher total feed energy intake available for production. Steers fed corn silage diets had significantly greater energetic efficiency (P less than .05) than those fed alfalfa haylage, due to increased use of ME to produce fat in the carcass. Protein type did not influence gain, feed or energetic efficiency, energy intake, or most carcass traits. A significant protein system x forage source interaction among the four diets was detected for crossbred steers fed corn silage and fish meal, for which there was significantly greater feed conversion with lower energy intake above maintenance, possibly due to better fiber digestion and(or) amino acid flow to the lower tract. Alfalfa haylage plus soybean meal diets decreased (P less than .05) the percentage of Holsteins grading USDA Choice or higher. These results indicate that corn silage, because of greater energy concentration, was a more desirable forage in feedlot diets composed of less than or equal to 40% forage and that protein type (soybean meal and fish meal) in growing diets is not an important factor in feedlot performance or carcass traits of Holstein or crossbred steers that are fed these diets.     

Effect of dietary canola oil on long‐chain omega‐3 fatty acid content in broiler hearts

Young and healthy broilers are susceptible to sudden death syndrome (SDS), which is caused by cardiac arrhythmia. The long‐chain ‘fish‐type’ omega‐3 fatty acids, eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), have cardioprotective anti‐arrhythmic effects in animals and humans. Raising the cardiac level of EPA and DHA in chickens may protect against SDS. However, fish oil as a source of EPA and DHA in poultry feed is costly and introduces undesirable properties to the meat. Whilst omega‐3 vegetable oils, such as canola oil, are cheaper and do not have a strong odour, they contain the short‐chain fatty acid α‐linolenic acid, which requires conversion to EPA and DHA after ingestion. We investigated the capacity for dietary canola oil to elevate cardiac EPA and DHA in broilers. Broilers were fed with diets containing either 3% canola oil or tallow, which is currently used in some commercial feeds. Upon completion of a 42 day feeding trial, canola oil significantly increased EPA and EPA + DHA in heart phospholipids relative to tallow. The elevation in cardiac EPA and EPA + DHA may provide anti‐arrhythmic effects and protect against SDS in poultry. This proof‐of‐concept biochemical study suggests that a larger study to assess the clinical outcome of SDS may be warranted.     

Environmentally sustainable production of food,feed and fuel from natural resources in the tropics

Responding to the challenges posed by global warming, peak oil and biofuels will require a paradigm shift in the practice of agriculture and in the role of live stock within the farming system. Farming systems should aim at maximizing plant biomass production from locally available diversified resources, processing of the biomass on farm to provide food, feed and energy and recycling of all waste materials. The approach that is the subject of this paper is that the generation of electricity can be a by-product of food/feed production. The concept is the fractionation of biomass into inedible cell wall material that can be converted to an inflammable gas by gasification, the gas in turn being the source of fuel for internal combustion engines driving electrical generators. The cell contents and related structures such as tree leaves are used as human food or animal feed. As well as providing food and feed the model is highly appropriate for decentralized small scale production of electricity in rural areas. It also offers opportunities for sequestration of carbon in the form of biochar the solid residue remaining after gasification of the biomass.     

Environmentally sustainable production of food,feed and fuel from natural resources in the tropics

Responding to the challenges posed by global warming, peak oil and biofuels will require a paradigm shift in the practice of agriculture and in the role of live stock within the farming system. Farming systems should aim at maximizing plant biomass production from locally available diversified resources, processing of the biomass on farm to provide food, feed and energy and recycling of all waste materials. The approach that is the subject of this paper is that the generation of electricity can be a by-product of food/feed production. The concept is the fractionation of biomass into inedible cell wall material that can be converted to an inflammable gas by gasification, the gas in turn being the source of fuel for internal combustion engines driving electrical generators. The cell contents and related structures such as tree leaves are used as human food or animal feed. As well as providing food and feed the model is highly appropriate for decentralized small scale production of electricity in rural areas. It also offers opportunities for sequestration of carbon in the form of biochar the solid residue remaining after gasification of the biomass.     

Soybean hulls, wheat middlings, and corn gluten feed as supplements for cattle on forage-based diets.

Soybean hulls, wheat midds, and corn gluten feed are viable alternative supplements for forage-fed cattle. All three result from the processing of major Unites States agricultural crops, so large supplies are available. Their value is better for ruminant animals than for monogastrics because they contain digestible fiber components. These byproducts are widely available throughout the Unites States and will generally be more economical than traditional feed grains or commercial feeds when used appropriately as supplements to forage-based diets. Knowledge about the composition of base forage must be used in planning supplementation strategies because base forages vary in protein and mineral content [9]. Soybean hulls alone may be a good selection in situations in which forages are adequate or high in protein. In situations where forage is marginal or deficient in protein, wheat midds, corn gluten feed, or a mix of soybean hulls and corn gluten feed might be most desirable. All three feeds can be variable in nutrient composition, so they should be analyzed to ensure a balanced nutrient level in diets. Soybean hulls are especially variable in crude protein content and should always be analyzed when forages are marginal or deficient in protein. Despite the fact that published energy levels are substantially lower, research has shown that soybean hulls and wheat midds have a value comparable to corn and soybean meal in forage-based diets. Corn gluten feed has also been comparable to corn and soybean meal in most reports but is closer in value to its published energy levels. In general, results with soybean hulls have been surprisingly good and consistent, whereas responses to wheat midds and corn gluten feed supplementation have been more variable and sometimes disappointing. Feeding rates for soybean hulls can range from low to extremely high depending on forage availability and desired performance. Wheat midds should be limited in most situations to 50% of the expected dry matter intake because of their rapidly digested starch content. Corn gluten feed should be limited to approximately 50% of expected dry matter intake because of its high sulfur content. Several research groups are currently evaluating self-feeding programs for these byproducts, and while the potential for health and production problems exist, results have been encouraging in most cases. Self-feeding would reduce the labor costs of hand feeding and could provide backgrounders with a program to expand cattle numbers on a limited land base.     

Dose‐Titration Effects of Fish Oil in Osteoarthritic Dogs

Background: Food supplemented with fish oil improves clinical signs and weight bearing in dogs with osteoarthritis (OA). Objective: Determine whether increasing the amount of fish oil in food provides additional symptomatic improvements in OA. Animals: One hundred and seventy‐seven client‐owned dogs with stable chronic OA of the hip or stifle. Methods: Prospective, randomized clinical trial using pet dogs. Dogs were randomly assigned to receive the baseline therapeutic food (0.8% eicosopentanoic acid [EPA] + docosahexaenoic acid [DHA]) or experimental foods containing approximately 2‐ and 3‐fold higher EPA+DHA concentrations. Both veterinarians and owners were blinded as to which food the dog received. On days 0, 21, 45, and 90, serum fatty acid concentrations were measured and veterinarians assessed the severity of 5 clinical signs of OA. At the end of the study (day 90), veterinarians scored overall arthritic condition and progression of arthritis based on their clinical signs and an owner interview. Results: Serum concentrations of EPA and DHA rose in parallel with food concentrations. For 2 of 5 clinical signs (lameness and weight bearing) and for overall arthritic condition and progression of arthritis, there was a significant improvement between the baseline and 3X EPA+DHA foods (P=.04, .03, .001, .0008, respectively) but not between the baseline and the 2X EPA+DHA foods. Conclusions and Clinical Importance: Increasing the amount of fish oil beyond that in the baseline food results in dose‐dependent increases in serum EPA and DHA concentrations and modest improvements in the clinical signs of OA in pet dogs.     

Markers for estimating digesta flow in pigs and the effects of dietary fiber

Effects of diluting the energy content of a corn-soybean meal diet with either alfalfa meal or corn cobs on nutrient digestibility and rate of passage of feed residues and particle markers were measured in crossbred (Yorkshire X Landrace X Chester White X Large White) barrows with a mean body weight of about 80 kg. The excretion pattern in the feces of Cr-mordanted diet and of rare earths initially bound individually to the mixed diet or to the corn or soybean meal suggested a model having a single age-dependent compartment with time delay. The compartmental turnover rate parameter (lambda 1) estimated by this model did not differ for the rare earths individually used to mark the corn-soybean meal diet (Yb), the corn (La) or the soybean meal (Sm). In contrast, lambda 1 for Cr was smaller (P less than .001) than that of the mean for the three rare earths. The residence time due to displacement flow (tau) did not differ among markers. These results were interpreted to indicate that the high specific gravity of Cr-mordanted feed slowed flow due to mixing but not due to displacement. Correlations between lambda 1 and tau were less than .71. These results suggested that the flow of rare earths initially bound to feed ingredients provides a reasonable estimate of the flow of their undigested residues through the gastrointestinal tracts of nonruminant animals. Inclusion of the fibrous feeds reduced digestibility of dry matter, cell contents, crude protein and acid detergent lignin and increased digestibility of cell walls, cellulose and acid detergent fiber. Digestibilities of cellulose and acid detergent fiber were greater with alfalfa than with corn cobs as the fiber source. Differences in digestibility of crude protein and acid detergent fiber existed due to litter in one replicate of the experiment. Variation in digestibility was not significantly related to variation in lambda 1 or tau within or among treatments and litters. This suggests that variations in lambda 1 and tau were not important causes of the observed variation in digestibility.     

Omega-3 fatty acids in the gravid pig uterus as affected by maternal supplementation with omega-3 fatty acids

Two experiments evaluated the ability of maternal fatty acid supplementation to alter conceptus and endometrial fatty acid composition. In Exp. 1, treatments were 1) the control, a corn-soybean meal diet; 2) flax, the control diet plus ground flax (3.75% of diet); and 3) protected fatty acids (PFA), the control plus a protected fish oil source rich in n-3 PUFA (Gromega, JBS United Inc., Sheridan, IN; 1.5% of diet). Supplements replaced equal parts of corn and soybean meal. When gilts reached 170 d of age, PG600 (PMSG and hCG, Intervet USA, Millsboro, DE) was injected to induce puberty, and dietary treatments (n = 8/treatment) were initiated. When detected in estrus, gilts were artificially inseminated. On d 40 to 43 of gestation, 7 gilts in the control treatment, 8 gilts in the PFA treatment, and 5 gilts in the flax treatment were pregnant and were slaughtered. Compared with the control treatment, the flax treatment tended to increase eicosapentaenoic acid (EPA: C20:5n-3) in fetuses (0.14 vs. 0.25 +/- 0.03 mg/g of dry tissue; P = 0.055), whereas gilts receiving PFA had more (P < 0.05) docosahexaenoic acid (DHA: C22:6n-3) in their fetuses (5.23 vs. 4.04 +/- 0.078 mg/g) compared with gilts fed the control diet. Both the flax and PFA diets increased (P < 0.05) DHA (0.60, 0.82, and 0.85 +/- 0.078 mg/g for the control, flax, and PFA diet, respectively) in the chorioallantois. In the endometrium, EPA and docosapentaenoic acid (C22:5n-3) were increased by the flax diet (P < 0.001; P < 0.05), whereas gilts receiving PFA had increased DHA (P < 0.001). The flax diet selectively increased EPA, and the PFA diet selectively increased DHA in the fetus and endometrium. In Exp. 2, gilts were fed diets containing PFA (1.5%) or a control diet beginning at approximately 170 of age (n = 13/treatment). A blood sample was collected after 30 d of treatment, and gilts were artificially inseminated when they were approximately 205 d old. Conceptus and endometrial samples were collected on d 11 to 19 of pregnancy. Plasma samples indicated that PFA increased (P < 0.005) circulating concentrations of EPA and DHA. Endometrial EPA was increased (P < 0.001) for gilts fed the PFA diet. In extraembryonic tissues, PFA more than doubled (P < 0.001) the EPA (0.13 vs. 0.32 +/- 0.013 mg/g) and DHA (0.39 vs. 0.85 +/- 0.05 mg/g). In embryonic tissue on d 19, DHA was increased (P < 0.05) by PFA (0.20 vs. 0.30 +/- 0.023 mg/g). Supplementing n-3 PUFA, beginning 30 d before breeding, affected endometrial, conceptus, and fetal fatty acid composition in early pregnancy. Dynamic day effects in fatty acid composition indicate this may be a critical period for maternal fatty acid resources to affect conceptus development and survival.     

Effects of fish oil on lymphocyte proliferation, cytokine production and intracellular signalling in weanling pigs.

It has been widely documented that fish oil attenuates inflammatory responses partially via down-regulation of T-lymphocyte function. To determine the anti-inflammatory role of fish oil in weanling pigs, we investigated the effects of fish oil and its functional constituents on peripheral blood lymphocyte proliferation, cytokine production and subsequent intracellular signalling in inflammatory-challenged weanling pig and in in vitro cultured lymphocytes. Fish oil (7%) or corn oil (7%) was supplemented to 72 crossbred pig (7.6 +/- 0.3 kg BW and 28 +/- 3 days of age) in a 2 x 2 factorial experiment that included an Eacherichia coil lipopolysaccharide (LPS) challenge (challenged or not challenged). On day 14 and 28 of the experiment, 200 microg/kg BW of LPS or an equivalent amount of sterile saline was administered to the pigs by intraperitoneal injection. Blood samples were collected on days 15 and 29 to determine peripheral blood lymphocyte proliferation, interleukin-1beta (IL-1beta) and interleukin-2 (IL-2) production. The results showed that inflammatory challenge decreased average daily gain (P < 0.05) and average daily feed intake (P < 0.05) during days 15-28. Fish oil supplementation had no effect on growth performance. Inflammatory challenge increased lymphocyte proliferative response to concanavalin A (Con A) (P < 0.05) following each challenge. Fish oil tended to suppress (P < 0.1) the proliferation following the first challenge. Similarly, fish oil tended to reduce IL-1beta production (P < 0.1) following the second challenge and IL-2 (P < 0.1) production following the first challenge in both challenged and unchallenged pigs compared with corn oil. In parallel in vitro experiments, peripheral blood lymphocytes of weanling pigs were incubated with various concentrations of eicosapentaenoic acid (EPA), docosahexaenoic acid (DHA) or linoleic acid (LA) (0, 20, 40, 60, 80, 100 microg/ml). EPA, DHA and high levels of LA predominantly suppressed IL-1beta (P < 0.05), IL-2 (P < 0.05) production and subsequent lymphocyte proliferation (P < 0.05). Low levels of LA increased (P < 0.05) IL-2 production. Compared with LA, EPA resulted in a stronger inhibition of lymphocyte proliferation (P < 0.05) and IL-2 (P < 0.01), and DHA resulted in a stronger inhibition of IL-1beta (P < 0.05) and IL-2 (P < 0.01). To elucidate the mechanism(s) by which fish oil and its functional constituents suppressed lymphocyte function, the kinetics of intracellular [Ca2+]i and protein kinase C activity were determined in in vitro experiments. EPA, DHA and LA exerted very similar dose-dependent stimulatory effects on intracellular Ca2+. EPA and DHA inhibited protein kinase C activity (P < 0.05), while LA had no significant effect (P > 0.05). These results suggest that fish oil and its functional constituents (EPA and DHA) exerted an anti-inflammatory effect by down-regulation of lymphocyte activation in weanling pigs, possibly by manipulation of intracellular signalling.     

碳水化合物与蛋白质同步降解对瘤胃发酵特性及微生物蛋白质合成的影响

本研究通过一系列的体外研究来确定酶和甲醛处理对碳水化合物和蛋白质的降解特性及同步降解碳水化合物和蛋白质对瘤胃体外发酵和微生物蛋白合成的影响.未处理玉米和酶处理玉米与豆粕或酶处理或甲醛处理豆粕相结合,制备6种不同同步指数的试验饲料.结果:使用未经酶处理的玉米时,高同步指数日粮的干物质消化率最高(P<0.05).但酶处理玉...     

玉米蛋白粉的深加工与高F值寡肽的利用

玉米蛋白粉（CGM）主要成分是玉米醇溶蛋白（Zein），玉米醇溶蛋白中支链氨基酸（BCAA）相对含量很高，因此，可以从CGM中分离提取玉米黄素、玉米醇溶蛋白和高F值生物活性寡肽（F值=BCAA／AAA，A从为芳香族氨基酸），高F值寡肽因其特有的生理功能而在生物医药和功能性食品等领域具有广阔的诱人应用前景。本文对玉米蛋白粉的加工开发利用做了系列综述，并展望了高F值生物活性寡肽的应用前景和潜在研究价值。     

Fatty acid profile and oxidative stability of pork as influenced by duration and time of dietary linseed or fish oil supplementation

In this experiment, the effect of duration and time of feeding n-3 PUFA sources on the fatty acid composition and oxidative stability of the longissimus thoracis (LT) muscle was investigated. Linseed (L) and fish oil (F), rich in alpha-linolenic acid and eicosapentaenoic and docosahexaenoic acid (EPA and DHA), respectively, were supplied equivalent to a level of 1.2% oil (as fed), either during the whole fattening period or only during the first (P1; 8 wk) or second (P2; 6 to 9 wk until slaughter) fattening phase. All diets were based on barley, wheat, and soybean meal and were fed ad libitum. Crossbred pigs (n = 154; Topigs 40 x Piétrain) were randomly allotted to the 7 feeding groups. In the basal diet (B), only animal fat was used as the supplementary fat source. Three dietary groups were supplied the same fatty acid source during both fattening phases (i.e., group BB, LL, and FF). For the other 4 dietary groups, the fatty acid source was switched after the first phase (groups BL, BF, LF, and FL; the first and second letter indicating the diet in P1 and P2, respectively). Twelve animals per feeding group were selected based on average live BW. The LT was analyzed for fatty acid composition; lipid stability (thiobarbituric acid-reactive substances) and color stability (a* value, % of myoglobin pigments) were determined on the LT after illuminated chill storage for up to 8 d. The alpha-linolenic acid, EPA, and docosapentaenoic acid incorporation was independent of the duration of linseed feeding (1.24, 0.54, and 0.75% of total fatty acids, respectively, for group LL). Supplying fish oil during both phases resulted in the greatest EPA and DHA proportions (1.37 and 1.02% of total fatty acids; P < 0.05), but the content of docosapentaenoic acid was not affected. The proportion of DHA was greater when fish oil was administered during P2 compared with P1 (P < 0.05). There was no effect of diet on meat ultimate pH and drip loss or on lipid or color oxidation.     

EPA和DHA对断奶仔猪淋巴细胞转化和细胞内信号分子的影响

研究二十碳五烯酸(EPA)和二十二碳六烯酸(DHA)对断奶仔猪外周血淋巴细胞转化及相关细胞内信号分子的影响.结果表明(1)EPA和DHA剂量依赖性地抑制淋巴细胞转化(P ＜ 0.05);(2)EPA和DHA剂量依赖性地刺激一氧化氮(P ＜ 0.001)、环腺苷酸(P ＜ 0.001)和环鸟苷酸(P ＜ 0.001)的产生,提高环腺苷酸/环鸟苷酸比例(P ＜ 0.05);(3)EPA和DHA使细胞内游离Ca2 浓度出现瞬间上升,其上升幅度有明显的剂量依赖关系;(4)EPA和DHA剂量依赖性地抑制蛋白激酶C活性(P ＜ 0.05),而对蛋白激酶A活性无影响.EPA和DHA抑制仔猪淋巴细胞功能,其作用可能是通过改变细胞内信号转导实现的.     

玉米DDGS作为反刍动物能量或蛋白饲料原料的营养价值

为准确评价不同来源的DDGS作为反刍动物饲料的营养价值,研究采用美国康奈尔大学净碳水化合物和净蛋白质体系(CNCPS)的原理和方法,测定和分析了8种不同来源的玉米干酒糟及其可溶物(DDGS)的营养价值及营养特性,并且把DDGS和当地的玉米、豆粕的营养价值进行了比较。经测定,8种DDGS常规营养成分(占干物质%)的平均数为:粗蛋白(28.28±2.56)%,粗脂肪(11.01±1.03)%,碳水化合物CHO(56.10±5.65)%,NDF(45.06±4.24)%,ADF(18.94±1.52)%,木质素(3.67±0.35)%。在蛋白组分中,PA、PB1、PB2、PB3和PC分别占粗蛋白的(5.67±0.27)%、(4.9±0.51)%、(22.89±2.39)%、(49.8±4.77)%和(16.68±2.61)%,其中,PA、PC的含量变化大,变异系数分别为8.8%和16.7%。在碳水化合物组分中,CA、CB1、CB2和CC分别占CHO的(25.74±0.82)%、(13.74±3.14)%、(44.76±4.49)%和(15.76±1.23)%。作为能量饲料和玉米相比,DDGS的载能物质主要是脂肪和可消化纤维,所估计的产奶净能低于玉米(6.56MJ/kg比7.73MJ/kg)。作为蛋白质饲料和豆粕相比,DDGS中主要的蛋白质组分是慢速降解蛋白(PB3),且能为小肠提供多于豆粕的过瘤胃蛋白(96.50g/kg比62.57g/kg)。上述结果表明,不同来源或不同生产工艺产生的DDGS营养价值差异较大,可溶性蛋白的含量和酸性洗涤不溶蛋白质含量的变化是引起DDGS营养价值变化的主要原因。因此,改善玉米DDGS的加工工艺,准确测定DDGS蛋白质组分和碳水化合物组分的含量是科学利用DDGS饲料产品的必要条件。