Effects of type of fat in the diet on iron bioavailability assessed in suckling and weanling rats

Differences in iron bioavailability from human milk and milk formulas may in part be due to differences in lipid composition. We investigated the short and long term effects of diets based on different fats [corn, coconut, olive, or soy oil, human milk fat (HMF) and a formula fat blend (FF)] on iron absorption in rats. Suckling rat pups dosed with 59Fe-labeled diets containing different fat sources were killed after 6 h, and blood and individual tissues were counted. Iron availability was estimated by % 59Fe in blood. Pups dosed with a more saturated fat (coconut oil) had a higher % 59Fe in blood than those fed other fat sources. Weanling rats were used to determine iron bioavailability from fat sources using both the hemoglobin repletion method and whole body counting. Hemoglobin regeneration was significantly higher for rats fed the HMF diet (8.4 +/- 0.5 g/dl) than from the FF diet (6.5+/-0.6 g/dl) or the corn oil diet (less saturated) (6.4 +/- 0.3 g/dl). Rats fed diets based on coconut oil (more saturated) had significantly higher % 59Fe retention (61.6 +/- 1.4) than rats fed diets based on FF (49.8 +/- 3.4). There was a significant positive association between oleic acid in the diet and oleic acid in the intestinal mucosa (r = 0.95, p < 0.05) and between linoleic acid in the diet and linoleic acid in the intestinal mucosa (r = 0.97, p < 0.05) suggesting that the dietary treatment altered the fatty acid composition of the brush border membrane. Our results suggest that saturated fats may increase iron absorption and that part of this may be achieved by changes in the fatty acid composition of the intestinal mucosa. Hemoglobin regeneration and % 59Fe retention data suggest that differences in iron absorption from infant diets may in part be due to differences in fat composition. Therefore, lipid composition of infant formulas should also be taken into consideration as a factor influencing iron bioavailability.     

Dietary effects of allopurinol and sulfinpyrazone on development, survival, and reproduction of German cockroaches (Dictyoptera: Blattellidae).

Diets containing two gout medications, allopurinol and sulfinpyrazone, were fed ad libitum to first- or second-instar German cockroaches for 15 wk or until 100% mortality was reached. Cockroaches fed greater than or equal to 0.10% allopurinol diets weighed significantly less than those fed the control diet. Mortality of cockroaches fed diets containing greater than or equal to 0.05% allopurinol was significantly greater than those fed the control diet. The LT50 (6.1 wk) of cockroaches fed diets containing 0.10% allopurinol was significantly less than those fed any other diet containing allopurinol. LT50s and slopes were proportional and inversely related, respectively, to percentage of allopurinol in the diet. The addition of sulfinpyrazone to allopurinol diets minimally enhanced the blatticidal nature of the diets. Nymphs fed diets containing greater than or equal to 0.05% allopurinol experienced significant delays in adult emergence. Cockroaches fed greater than or equal to 0.01% allopurinol diets aborted a significantly greater percentage of their oothecae than those fed the 0.001% allopurinol or control diets. Hatched oothecae from cockroaches fed the 0.01% allopurinol diet had significantly fewer nymphs than those fed the 0.001% allopurinol or control diets. Percentage of oothecae aborted and number of nymphs per hatched ootheca from cockroaches fed a 2% sulfinpyrazone diet did not differ significantly from the control.     

Enhancing effect of dietary vinegar on the intestinal absorption of calcium in ovariectomized rats.

We studied the effect of dietary vinegar on calcium absorption by using ovariectomized rats fed on a low-calcium diet. The apparent absorption of calcium was higher when the rats were fed on a diet containing 1.6% vinegar for 32 days than when fed on a diet without vinegar (P < 0.05). The calcium content in the femur of the rats given diets containing 0.4% and 1.6% vinegar were also higher (P < 0.05). The serum parathyroid hormone level was lower and the crypt depth of the duodenum thicker in the rats fed on a diet containing 1.6% vinegar (P < 0.05). These results suggest that dietary vinegar enhanced intestinal calcium absorption by improving calcium solubility and by the trophic effect of the acetic acid contained in vinegar, which would reduce the bone turnover caused by ovariectomy and be helpful in preventing osteoporosis.     

黄颡鱼饲料中添加谷胱甘肽降低藻毒素毒性作用的研究

通过60d的生长实验研究饲料中不同含量的谷胱甘肽(GSH)对黄颡鱼(Pelteobagrus fulvidraco Richardson)摄食含蓝藻粉饲料后的毒性保护作用。共配制6种近似等氮等能(粗蛋白45%,总能19.5kJ/g)的实验饲料。以不添加蓝藻粉、不添加GSH的饲料组作为正对照,其他5种饲料均添加7.5%的藻粉,微囊藻毒素(Microc ystins,MCs)含量约为58μg/g,GSH添加量分别为:0(负对照)、200、500、800和1400mg/kg。实验结果表明,第1至第30天时,负对照组与正对照组实验鱼的摄食率无显著性差异(P>0.05)。第31至第60天时,负对照组实验鱼的摄食率显著高于正对照和其他GSH添加组(P0.05),但各GSH添加组肾脏中GSH显著低于正对照而高于负对照(P<0.05)。200、500和800mg/kg GSH添加组肝脏和肌肉中丙二醛(MDA)含量显著低于负对照(P<0.05)。在整个实验期间,随着饲料中GSH含量的增加,肝脏、肾脏、全肠和肌肉中微囊藻毒素含量先显著下降,当GSH添加量为500和800mg/kg时达到稳定,直至GSH添加量为1400mg/kg时显著上升。根据对黄颡鱼增重,肝脏和肌肉中MDA的含量以及组织中毒素的分析,在饲料中添加500-800mg/kg GSH可以有效缓解黄颡鱼饲料中微囊藻毒素的毒性。       

果胶高载引起的黄颡鱼绿肝症和肝纤维化与肠道菌群失调的关联

日粮中黏性膳食纤维果胶较高时可引起黄颡鱼(Pelteobagrus fulvidraco)的绿肝症和肝纤维化, 研究旨在探讨肠道菌群在上述病理过程中的潜在作用。分别配制含30%糊精和果胶的对照日粮和高果胶日粮, 命名为CON和PEC日粮, 再在CON和PEC日粮中添加0.2%的抑菌剂甲硝唑, 命名为CONM和PECM日粮。用4种日粮饲养初始体质量为(21.5±3.6) g/尾的黄颡鱼, 分别于饲养7d和56d后采样分析。16S rRNA分析结果显示, 日粮中添加甲硝唑抑制了梭杆菌门(Fusobacteria)和厚壁菌门(Firmicutes)的细菌, 使变形菌门(Proteobacteria)成为第一优势菌, 表明甲硝唑发挥了抑菌作用。饲养7d后CON组、CONM组、PEC组和PECM组的绿肝率分别为0、12%、27%和88%, 饲养56d后各组鱼肝脏纤维化程度依次增强。甲硝唑显著降低了肠道内容物中胆盐水解酶活力。肝脏中参与胆汁酸合成、转运及调控的基因表达活性与绿肝率及血清中胆汁酸含量不一致。上述结果提示肠道菌群紊乱可能是引起绿肝症和肝纤维化的重要原因, 胆汁酸可能介导了此病理过程。     

Physiological effects of water-soluble soybean fiber in rats.

Four-week-old rats were fed on diets containing either no dietary fiber (DF) or a DF source (WSSF, ISF or cellulose) for 4 weeks. The DF level was adjusted to 5%. The WSSF diet contained 3% and 2%, respectively, of WSSF and cellulose. No rat in any group experienced diarrhea, and none of the experimental diets suppressed the growth of rats, the apparent absorption of major nutrients being almost 100%. However, the rate of degradation of DF during the digestive process was significantly different (p < 0.05, cellulose, 23.6%; WSSF with cellulose, 64.5% (WSSF degradation only was 91.8%); and ISF, 77.6%). The plasma and liver lipid levels were within normal ranges, although the liver cholesterol level in those rats fed on WSSF and ISF was significantly lower (p < 0.05) than in those fed on cellulose. The cecal organic acid contents were in the order of WSSF > ISF > cellulose > DF-free. Furthermore, WSSF was effective in shortening the gastrointestinal transit time. The results indicate that WSSF seems to have favorable effects on the intestinal functions.     

Effect of lard and corn oil intake on serum lipids in young men

An experimental diet with lard (30 g/day for 7 days) and corn oil (30 g/day for 7 days) on high carbohydrate (basal diet) was given to four healthy Japanese young men and the effect of diets containing different fat on serum lipids was examined. Serum total cholesterol was increased significantly from a basal diet of 106 +/- 23 to 141 +/- 26 mg/dl on lard diet, and then decreased significantly (p less than 0.05) to 111 +/- 22 mg/dl on corn oil diet. Serum triglycerides increased significantly (p less than 0.01) from 66 +/- 38 to 173 +/- 32 mg/dl on basal diet. Serum HDL-cholesterol was decreased significantly (p less than 0.01) from 41.9 +/- 1.6 to 31.2 +/- 3.8 mg/dl on lard diet and increased significantly (p less than 0.05) to 41.9 +/- 4.6 mg/dl on corn oil diet. Serum HDL-cholesterol fraction was decreased significantly (p less than 0.01) from 41.6 +/- 4.9 to 28.1 +/- 3.2% on basal diets, but increased significantly (p less than 0.05) to 44.3 +/- 3.1% on lard diet, and then decreased to 36.3 +/- 2.5% on corn oil diet. Serum HDL phospholipid fraction decreased significantly (p less than 0.05) from 62.5 +/- 6.7 to 50.7 +/- 1.8% on basal diet and increased significantly (p less than 0.05) to 60.4 +/- 1.0% on lard and corn oil diet. Serum phospholipids did not change by experimental diets. It is concluded that lard and corn oil have different and specific roles in lipid metabolism.     

Liver and muscle proteolytic activity in male growing rats fed a field bean (Vicia faba L.) diet

Total liver cathepsin A and D and gastrocnemius acid proteolytic activities have been evaluated in male growing rats fed ad libitum over periods of 15 and 30 days on 20%-protein diets containing either casein or raw field bean (Vicia faba L.) as protein sources. It has been found that, compared to the control casein-fed rats, those fed the legume diet exhibited a marked reduction (p less than 0.05) in the rate of growth and protein efficiency rate; liver proteolytic activity increased with ageing in the two dietary treatments and was found to be significantly higher (p less than 0.05) in the legume-fed rats. However, muscle proteolytic activity decreased with ageing and proved significantly increased (p less than 0.05) in the legume-fed rats.     

Pancreatic adaptation to dietary lipids is mediated by changes in lipase mRNA

Lipase activity, rates of biosynthesis of lipase (triacylglycerol acylhydrolase, EC 3.1.1.3) and amylase (1,4-alpha-D-glucan glucanohydrolase, EC 3.2.1.1) as well as concentrations of their corresponding mRNAs were measured in the pancreatic tissue of rats fed isocaloric and isoprotein diets with inverse changes in the amounts of lipids and carbohydrates. A control diet (3% sunflower oil--62% starch) and three lipid-rich diets (10% sunflower oil--46.2% starch, 25% sunflower oil--12.5% starch and 30% sunflower oil--1.25% starch) were fed to rats for 10 days. Ingestion of the 10% lipid diet already resulted in a 1.4-fold increase in lipase activity while a 2.4-fold increase was observed with the other 2 high-lipid low-carbohydrate diets. Similarly, 1.3- and 3.1-fold increases in the total rate of protein synthesis were measured in pancreatic lobules of rats fed 10 and 25% or 30% lipid diets, respectively, as compared with control animals. While absolute lipase synthesis showed an important increase during the dietary manipulation (1.7- and 5.9-fold, respectively), amylase synthesis was significantly lower (1.1- and 1.5-fold, respectively). The level of lipase mRNA, as measured by dot-blot hybridization with the corresponding specific cDNA, showed a 2.2-fold increase (10% lipid diet) and a 3.9-fold increase (25% lipid diet), whereas the level of amylase mRNA showed only 1.1- and 1.3-fold increases under the same experimental conditions. These data demonstrated that protein-specific synthesis rates more accurately reflected pancreatic adaptive states than tissue levels of enzymes.(ABSTRACT TRUNCATED AT 250 WORDS)     

Effects of dietary sulfur amino acids and crude protein on the performance of finishing broilers

The effects of different combinations of dietary methionine+cystine (Met+Cys) and dietary crude protein (CP) in finishing broilers were investigated in two growth studies. In Exp. 1, male broilers 29 to 42 days of age were fed 18 diets containing 16.9%, 18.7%, or 20.4% CP with six levels of Met+Cys within each protein level. Similarly, in Exp. 2 another 12 diets containing either 18.0 or 21.5% CP were fed to male broilers 29 to 48 days of age.

In general, the Met+Cys requirement for optimum feed conversion was higher than for maximum growth. In both experiments, between 0.80% and 0.85% methionine+cystine optimized feed conversion. These dietary levels were valid for a 13.05 MJ ME/kg diet fed to broilers growing from 1.2 kg to 2.2 kg (Exp. 1), or for a 13.60 MJ ME/kg diet fed to broilers growing from 1.3 kg to 3.0 kg (Exp. 2).

The Met+Cys requirement was not consistently affected by the dietary CP content in Exp. 1. In Exp. 2, increasing dietary CP from 18.0% to 21.5% tended to increase the Met+Cys requirement for optimum feed conversion.

A dietary CP level of 18.0% to 18.7% supported performance and carcass fat deposition equal to diets containing 20.4% or 21.5% CP, respectively, when the sulfur amino acid content was adequate.     

Biological activity of phenolic compounds. Hepatic cytochrome P-450, cytochrome b5, and NADPH cytochrome c reductase in chicks and rats fed phenolic monomers, polymers, and glycosides

Eight experiments were conducted to determine effects of a phenolic polymer (Kraft wood lignin, Indulin), phenolic glycosides (cane molasses and wood molasses), and phenolic monomers (vanillin, vanillic acid, ferulic acid, and p-coumaric acid) on liver cytochromes P-450, cytochrome b5, and NADPH cytochrome c reductase in chicks and rats. Chicks fed 6.0% lignin had a higher (P less than 0.01) cytochromes P-450 content than did chicks fed 0% fiber, 6.0% wood cellulose (Solka Floc), or 6.0% arenaceous flour. NADPH cytochrome c reductase activity was not affected by treatment. Chicks fed 12.0% wood molasses had a higher (P less than 0.06) cytochromes P-450 level than did chicks fed 0% fiber or 6.0% wood molasses. Cane molasses incorporated at both 6.0 and 12.0% of the diet induced (P less than 0.05) cytochromes P-450 content over those of control-fed birds. Chicks fed 6.0% lignin, with or without antibiotic (bacitracin:neomycin sulfate, 2:1), had a higher (P less than 0.01) cytochromes P-450 level than did chicks fed control diets, with or without antibiotic. Additionally, chicks fed 6.0% lignin had lower (P less than 0.01) intestinal diaminopimelic acid (DAP) levels than did chicks fed 0% fiber. Rats fed 0% fiber, 6.0% wood cellulose, 6.0% arenaceous flour, or 6.0% lignin exhibited no difference in cytochrome level or activity among treatments. Chicks fed 0.5% vanillin, 0.5% vanillic acid, 0.5% ferulic acid, or 0.5% p-coumaric acid had comparable cytochromes level and activity compared with chicks fed no phenolics. Chicks fed 0.5% p-coumaric acid had lower (P less than 0.05) rates of gain than did chicks fed control or other phenolic-containing diets. Rats fed these phenolics had similar cytochromes P-450 content among treatments.     

Improvement of nutritive value of grass pea (Lathyrus sativus) seed meal in the formulated diets for rohu, Labeo rohita (Hamilton) fingerlings after fermentation with a fish gut bacterium

Eight isonitrogenous (35% crude protein approximately) and isocaloric (4.0 kcalg(-1) approximately) diets were formulated incorporating raw and fermented grass pea (Lathyrus sativus) seed meal at 10%, 20%, 30% and 40% levels by weight into a fish meal based diet and fed to rohu, Labeo rohita, fingerlings for 80 days and fish performance was studied. A particular bacterial strain (Bacillus sp.) isolated from the intestine of adult common carp (Cyprinus carpio) reared in the wild having significant amylolytic, cellulolytic, lipolytic and proteolytic activities were used for fermentation of seed meal for 15 days at 37 degrees C. Fermentation of grass pea seed meal was effective in significantly reducing the crude fibre content and anti-nutritional factors, such as tannins, phytic acid and the neurotoxin, beta-ODAP and enhancing the available free amino acids and fatty acids. In terms of growth response, feed conversion ratio and protein efficiency ratio, 30% fermented grass pea seed meal incorporated diet resulted in significantly (P < 0.05) better performance of rohu fingerlings. In general, growth and feed utilization efficiencies of fish fed diets containing fermented seed meal were superior to those fed diets containing raw seed meal. The apparent protein digestibility (APD) values decreased with increasing levels of raw seed meal in the diets. The APD for raw seed meal was lower at all levels of inclusion in comparison to those for the fermented seed meals. The highest deposition of carcass protein was recorded in fish fed the diet containing 40% fermented seed meal. The results indicated that fermented grass pea seed meal can be incorporated in carp diets up to 30% level compared to 10% level of raw seed meal.     

大豆低聚糖对牙鲆营养效应的研究：Ⅱ 消化率和消化生理

本试验比较研究了不同蛋白源(鱼粉,FM;大豆分离蛋白,SPI)基础饲料中添加大豆低聚糖(SBOS)对牙鲆(Paralichthys olivaceus)消化道(胃、幽门盲囊、前肠、中肠和后肠)和肝脏消化酶活性、饲料表观消化率和消化道(胃、小肠)组织结构的影响。分别以FM、SPI作为主要蛋白源,配制了4种等氮等能饲料。其中,饲料FM、SPI分别以FM、SPI作为主要蛋白源;饲料FMO、SPIO分别在饲料FM、SPI基础上添加10%SBOS(水苏糖：2.61%;棉籽糖：0.61%)。试验表明：①饲料中添加SBOS普遍降低了牙鲆消化道和肝脏蛋白酶活性,但差异均不显著(p > 0.05)。FM基础饲料中添加SBOS显著降低了肝脏脂肪酶活性(p < 0.05),而对消化道脂肪酶活性无显著影响;SPI基础饲料中添加SBOS显著提高了前肠脂肪酶活性,降低了胃和中肠脂肪酶的活性,而对幽门盲囊、后肠和肝脏脂肪酶活性均无显著影响。FM基础饲料中添加SBOS显著降低了中肠淀粉酶活性,提高了胃淀粉酶活性(p < 0.05),而对幽门盲囊、前肠、后肠和肝脏淀粉酶活性无显著影响;SPI基础饲料中添加SBOS显著提高了胃和前肠淀粉酶活性,降低了中肠脂肪酶活性(p < 0.05),而对幽门盲囊、后肠和肝脏淀粉酶活性无显著影响;②FM基础饲料中添加SBOS显著降低了饲料干物质表观消化率(p < 0.05),而对粗蛋白、粗脂肪和能量表观消化率均无显著影响(p > 0.05)。SPI基础饲料中添加SBOS对干物质、粗蛋白、粗脂肪和能量表观消化率均无显著影响;③饲料中添加SBOS对牙鲆胃和小肠组织结构均无明显负面影响。试验结果表明,饲料中添加SBOS对牙鲆消化道和肝脏消化酶活性、饲料表观消化率和消化道组织结构均没有表现出明显的负面效应;大豆蛋白源中含有的SBOS不是影响牙鲆对其利用率差的主要因素。     

Effects of Dietary Energy Sources on Post Mortem Glycolysis,Meat Quality and Muscle Fibre Type Transformation of Finishing Pigs

Dietary energy source can influence muscle glycogen storage at slaughter. However, few studies have demonstrated whether the diet-induced change of muscle glycogen is achieved by the transformation of muscle fibre type. This study investigated the effects of dietary energy sources on meat quality, post mortem glycolysis and muscle fibre type transformation of finishing pigs. Seventy-two barrows with an average body weight of 65.0 ± 2.0 kg were selected and were allotted to three iso-energetic and iso-nitrogenous diets A, B or C, and each treatment consisted of three replicates (pens) of eight pigs each. Diet A contained 44.1% starch, 5.9% crude fat and 12.6% neutral detergent fiber (NDF); diet B contained 37.6% starch, 9.5% crude fat and 15.4% NDF; and diet C contained 30.9% starch, 14.3% crude fat and 17.8% NDF. The duration of the experiment was 28 days. After feed withdrawal 12 h, 24 pigs (eight per treatment) were slaughtered, samples from M. longissimus lumborum (LL) were collected for subsequent analysis. The results showed that pigs fed diet C had lesser average daily gain, average daily feed intake and back fat depth than those fed diet A (P<0.05). Diet C increased pH_45min (P<0.05) and decreased drip loss (P<0.05) in LL muscles compared with diet A. Meat from pigs fed diet A showed increased contents of lactate and greater glycolytic potential (GP) compared with those fed diet C (P<0.05). Greater mRNA expression of myosin heavy-chain (MyHC)-I and IIa and lesser expression of MyHC-IIx and IIb (P<0.05) in LL muscles were found in pigs fed diet C, than in pigs fed diet A. In addition, pigs fed diet C resulted in downregulation of miR23a and upregulation of miR409 and miR208b (P<0.05), associated with conserved changes of their corresponding targets. These findings indicated that diets containing low starch and high fibre were beneficial in reducing muscle glycolysis, improving meat quality of finishing pigs. This reduction of GP may be partially associated with the improvement of oxidative fibre composition in LL muscle, and the change in myofibre type may be correlated with the change in the miRNA expression.     

Meat meal in the diet of the early-weaned pig IV. The supplementation of diets with tryptophane,lysine and methionine

Two experiments were conducted with 72 pigs between 28 and 56 days of age to study the effect of tryptophane supplementation on their performance when fed on diets containing wheat and meat meal.In the first experiment, pigs were fed on a basal diet (Diet 1) or on the same diet supplemented with calcium dihydrogen phosphate (Diet 2), bone meal (Diet 3) or bone meal plus tryptophane (Diet 4), all to 3.1% calcium. The weight gains of the pigs (315 g day^?1) fed on Diet 3 were significantly lower than that of the pigs fed on the other three diets (363 g day^?1). The feed conversion ratios showed a similar trend. Diet 3 contained 0.16% tryptophane while the other diets contained 0.18–0.19% tryptophane. The crude protein, lysine and methionine contents of all diets were similar.In the second experiment, a basal diet containing meat meal and bone meal was supplemented with tryptophane, lysine plus methionine or all three amino acids. Feed intake was increased by all amino acid supplements. Weight gains were improved significantly (57%) by the addition of all three amino acids to the diets, but the improvements due to tryptophane alone (28%) or methionine plus lysine (35%) were not significant. Tryptophane supplementation alone or with lysine plus methionine increased the nitrogen retention of the pigs.It was concluded that the requirement for tryptophane of pigs between 28 and 56 days of age was greater than 0.16% of diets containing wheat and meat meal.     

The mouse bioassay for the detection of estrogenic activity in rodent diets: III. Stimulation of uterine weight by dextrose, sucrose and corn starch

We have shown previously that mice fed the American Institute of Nutrition (AIN-76A) purified diet experience a significant increase in uterine:body weight (U:BW) ratios when compared to the U:BW ratios of mice fed a closed formula natural ingredient diet (Certified Rodent Chow #5002) for 7 days. The AIN-76A purified diet contains 5% corn oil and 65% carbohydrates with 50% of the carbohydrates coming from sucrose or dextrose and 15% from corn starch. The objective of this study was to determine whether the fat and carbohydrate content contributed to the unexpected uterine growth promoting activity observed in mice fed the AIN-76A diet. Estrogen bioassays were performed using CD-1 mice weaned at 15 days of age and assigned randomly to the negative control diet (Certified Rodent Chow #5002) or to the positive control diet (#5002) containing 4 or 6 ppb DES for comparison or to the test diets. The test diets were prepared by adding sucrose, dextrose, corn starch, corn oil or soybean oil to the #5002 negative control diet at 10% w/w concentration. Uterine:BW ratios were determined at 7 days post-feeding. The uterine weights and the U:BW ratios of mice fed the test diets containing dextrose, corn starch, or corn oil, were increased significantly (P less than 0.05) over those of mice fed the negative control diet. The uterine weights and U:BW ratios of mice fed the test diets containing sucrose or soybean oil also were increased over those of mice fed the negative control diet. These increases in uterine weights and U:BW ratios were similar to the increases in uterine weights and U:BW ratios of mice fed the positive control diet containing 4 ppb DES. It was concluded that the fats and carbohydrates caused preferential increases in uterine weights and in U:BW ratios and may account for the estrogen-like uterine growth promoting activity observed in mice fed the AIN-76A purified diet.     

Effects of dietary protein and amino acid levels on the expression of selected cationic amino acid transporters and serum amino acid concentration in growing pigs

The absorption of lysine is facilitated by leucine, but there is no information regarding the effect of crude protein, lysine and leucine levels on the expression of cationic amino acid transporters in pigs. Therefore, an experiment was conducted with 20 pigs (14.9 +/- 0.62 kg initial body weight) to evaluate the effect of two protein levels, and the content of lysine, threonine, methionine and leucine in low crude protein diets on the expression of b(0,+) and CAT-1 mRNA in jejunum, Longissimus dorsi and Semitendinosus muscles and serum concentration of amino acids. Treatments were as follows: (i) wheat-soybean meal diet, 20% crude protein (Control); (ii) wheat diet deficient in lysine, threonine and methionine (Basal diet); (iii) Basal diet plus 0.70% L-lysine, 0.27% L-threonine, 0.10% DL-methionine (Diet LTM); (iv) Diet LTM plus 0.80% L-leucine (Diet LTM + Leu). Despite the Basal diet, all diets were formulated to meet the requirements of lysine, threonine and methionine; Diet LTM + Leu supplied 60% excess of leucine. The addition of lysine, threonine and methionine in Diet LTM increased the expression of b(0,+) in jejunum and CAT-1 in the Semitendinosus and Longissiums muscles and decreased CAT-1 in jejunum; the serum concentration of lysine was also increased (p < 0.01). Further addition of L-leucine (Diet LTM + Leu) decreased the b(0,+) expression in jejunum and CAT-1 in the Longissimus dorsi muscle (p < 0.05), increased the serum concentration ofleucine and arginine and decreased the concentration of isoleucine (p < 0.05). Pigs fed the Control diet expressed less b(0,+) in jejunum, and CAT-1 in the Semitendinosus and Longissiums muscles expressed more CAT-1 in jejunum (p < 0.05) and had lower serum concentration ofisoleucine, leucine and valine (p < 0.05), but higher lysine concentrations (p < 0.01) than those fed Diet LTM. These results indicated that both, the level and the source of dietary amino acids, affect the expression of cationic amino acid transporters in pigs fed wheat-based diets.     

Evaluation of Hydrodictyon reticulatum as protein source in feeds for Oreochromis (Tilapia) niloticus and Tilapia zillii

The green filamentous alga Hydrodictyon reticulatum was evaluated as a protein source in fish-meal substituted diets for Oreochromis niloticus and Tilapia zillii fingerlings. The fingerlings were fed in duplicate groups each of six different diets for 50 days. Five of the diets contained 30% crude protein supplied by varying proportions of fish meal and H. reticulatum meal. The five diets were formulated to supply fishmeal protein: H. reticulatum meal protein ratios of 30:0 (diet 1), 15:5 (diet 2), 20:10 (diet 3); 15:15 (diet 4), 10:20 (diet 5) respectively. A sixth diet containing only 25% crude protein supplied entirely by H. reticulatum meal was also fed. The best growth and protein utilization was obtained at lower levels of H. reticulatum substitution for both species of fish. Carcass analysis revealed a decrease in lipid contents of the fishes with increasing levels of the alga in the diet.     

Differences in portal flow rates of amino acids and liver composition between rats fed casein or lactalbumin

The portal appearance rates and net rates of amino acids' absorption were studied in rats fed semi-synthetic diets containing either casein or lactalbumin (CAS and LA, respectively) as the only protein sources. Rats were pre-adapted to the experimental diets for 5 days prior to the absorption studies. Rats fed the LA diet had higher (p < 0.05) portal vein concentrations of free essential amino acids than those fed the CAS diet at 0, 60, 105 and 150 min after feeding. Portal and arterial concentrations of arginine, leucine, tryptophan, lysine and methionine were higher (p < 0.05) in rats fed LA at most time points tested, while concentrations of tyrosine were higher (p < 0.05) in CAS fed rats. When portal flow rates were compared, values for arginine, threonine, alanine, leucine, tryptophan and lysine were higher (p < 0.05) in LA at most time points tested, while proline, tyrosine and valine were higher (p < 0.05) for CAS fed rats after 60 and 105 min feeding. Portal blood flow varied (p < 0.05) with time in rats fed protein-free or LA diets, and was higher (p < 0.05) than that of CAS at 105 min. Intestinal net rates of absorption of tyrosine, valine, leucine and lysine were higher (p < 0.05) for LA fed rats as compared to those fed CAS at most time points tested, while alanine and proline net rates were higher (p < 0.05) for CAS fed rats at 60, 105 and 150 min. Amounts of protein in stomach contents of rats fed the CAS diet were significantly higher (p < 0.05) than those in LA fed rats at 60, 105 and 150 min after feeding. The relative liver weight of the rats fed the CAS diet was lower (p < 0.05) than that of animals fed the LA diet. Lower (p < 0.05) liver glycogen and lipid contents were determined in rats fed CAS diet respect to LA or protein-free fed rats. Results indicate that dietary and plasma amino acids profile are only partially related, and that under normal feeding conditions amino acids from CAS and LA are absorbed at different rates, which is likely to affect liver composition and metabolism.     

Replacement of maize by rumen filtrate fermented corn-cob in layer diets

Laying hens (50 weeks in-lay) were fed for 8 weeks on diets containing corn-cobs fermented with rumen filtrate. The fermented corn-cob was included in the diets at 0%, 5.0%, 10.0%, 15.0% and 20.0% of the total diet at the expense of maize. Feed intake was not significantly (P>0.05) different, although birds on the control diet consumed slightly more feed than birds on the fermented corn-cob based diets. Hen day production and feed per dozen eggs decreased with increase in dietary level of corn-cob (P<0.05). Yolk colour was significantly (P<0.05) affected, rumen filtrate fermented corn-cob appear to promote better yolk coloration. Egg weight and shell thickness were not significantly influenced by dietary treatment. The overall results appear to suggest that rumen filtrate fermentated corn-cob could provide a material that holds promise as a good alternative to maize because of its enhanced crude protein value and reduced crude fibre content.