Haemolymph amino acid and sugar levels in locusts fed nutritionally unbalanced diets

Aspects of pre- and post-ingestive compensation were investigated in locusts (Locusta migratoria) fed nutritionally unbalanced artificial diets containing 7% protein and 21% digestible carbohydrate (7:21) or 21% protein and 7% digestible carbohydrate (21:7). Feeding behaviour and haemolymph levels of amino acids and sugars were measured in locusts fed ad libitum on these diets. Locusts fed the high-protein diet had chronically elevated haemolymph levels of 15 out of 19 amino acids measured compared to locusts fed the low protein diet. However, haemolymph levels of lysine, alanine, aspartic acid and glutamic acid did not differ between diets, suggesting some specific regulatory mechanism for these amino acids. Haemolymph glucose and trehalose reflected levels of carbohydrate in the diets, being high in insects fed diet 7:21 relative to those given diet 21:7. These data are discussed in relation to the physiological and behavioural bases of nutritional homeostasis.Abbreviations AA amino acid(s) - PRO protein - CHO carbohydrate - PBS phosphate-buffered saline - MW molecular weight     

Amino acid supplementation of methanol-grown dried microbial cells in diets for young chicks

Growth rates and efficiency of food conversion of young chicks fed on diets marginally limiting in total nitrogen and containing 150 g/kg diet of flash-dried microbial cells (MC) with and without amino acid supplements, were measured in three experiments. Performance of these animals was compared with that of groups fed on a methioninefortified soya bean meal (SBM) control diet. In all experiments, chicks fed on the SBM control diet grew faster and were more efficient than chicks fed on the basal unsupplemented MC diet. In Experiment 1, arginine supplementation markedly enhanced weight gain and efficiency of food utilisation of chicks offered the basal MC diet; methionine had no effect. The second experiment demonstrated that a supplement containing methionine, arginine and tryptophan was more effective in augmenting the nutritional value of MC than either methionine with arginine or tryptophan with arginine. In the final experiment, weight gain and food intake of chicks fed on MC with supplements of arginine, methionine and tryptophan were increased markedly by additions of lysine and glutamic acid but not by addition of lysine alone. In all experiments, performance of animals in MC supplemented groups was lower than that of animals fed on the SBM control diet.     

Changes in amino acid composition in the tissues of African catfish (Clarias gariepinus) as a consequence of dietary L-carnitine supplements

A study was undertaken to examine the effect of different amounts of dietary lysine (13 and 21 g kg^?1 diet), lipid (80 and 160 g kg^?1 diet) and L ‐carnitine (0.2 and 1.0 g kg^?1 diet) on growth performance, proximate composition and amino acid metabolism of the African catfish (Clarias gariepinus). Juvenile African catfish (23 ± 1.5 g/fish) were stocked into 70‐L aquaria (16 aquaria, 28 fish/aquarium) connected to a recirculation system during a maximum period of 74 days. All groups were fed at a level of 24 g kg^?0.8 day^?1 in an experiment run at pair feeding. Animals receiving 1.0 g carnitine accumulated up to six times more carnitine in their tissues than animals receiving 0.2 g (P < 0.05). Acyl‐carnitine and free L ‐carnitine levels increased in the whole body and in tissues. Dietary L ‐carnitine supplements increased protein‐to‐fat ratios in the body, but did not affect growth rate. Protein‐to‐fat ratios were only affected when the biosynthesis capacity of L ‐carnitine was restricted due to low lysine levels and when there was a shortage of dietary fat. When lysine was offered at 21 g kg^?1 feed, dietary L ‐carnitine supplements did not affect the amino acid concentrations of body tissues. Dietary L ‐carnitine supplements raised the concentration of glutamic acid > aspartic acid > glycine > alanine > arginine > serine > threonine in skeletal muscle tissue (P < 0.05). Total amino acid concentration in muscle and liver tissues (dry‐matter basis) increased from 506 to 564 and from 138 to 166 mg g^?1, respectively, when diets were offered with high L ‐carnitine, low lysine and low fat levels. These data suggest that dietary L ‐carnitine supplementation may increase fatty acid oxidation and possibly decrease amino acid combustion for energy.     

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.     

EFFECTS OF DIFFERENT LEVELS OF DIETARY PROTEIN ON BRAIN GLUTAMATE DEHYDROGENASE AND DECARBOXYLASE IN YOUNG ALBINO RATS

Abstract— Studies were carried out to identify the minimum levels of protein (casein) needed in the diet in order to prevent or reverse the deficits in brain enzymes previously found with protein deficiency. Groups of weanling albino rats were fed diets containing variable amounts of protein (5, 8, 10, 15 or 20 per cent in experiment I, and 5, 6, 7, 8 or 20 per cent in experiment II) for 5 or 10 weeks. Deficits in brain wt and brain glutamate dehydrogenase and decarboxylase were found to be prevented by a diet containing 8 per cent or more of protein, although for optimum growth 15 per cent protein in the diet was found to be necessary. Groups of rats were fed a 5 or 20% protein diet for 10 weeks after which the 5% protein animals were either continued on the diet for another 10 weeks or changed to one containing 8, 10, 15 or 20% protein. The brain enzyme deficits found with the 5% protein diet were found to be fully reversed by feeding a 10% protein diet during rehabilitation.     

Low Tryptophan and Protein in the Diet During Development Increase the Susceptibility to Convulsions in Adult Rats

Tryptophan (TRY) is the precursor for serotonin (5-HT) synthesis. Common maize has low protein content with low concentration of TRY and lysine. A diet based on two strains of corn differing in their TRY content were given to adult female rats, prior mating, during pregnancy and lactation. Same diets were offered to their male offspring after weaning until reaching 60-days old. The pattern and severity of the convulsive phenomenon induced by monosodium glutamate (MSG) in a well established model of Status epilepticus were evaluated in comparison with data from animals of two control groups: (a) rats fed a hypoproteic (8% protein) diet, and (b) rats fed a normal Purina chow diet (23% protein). Significant increased susceptibility to convulsions was observed in both groups of rats fed the corn-based diets. However, the animals fed the common corn-based diet (8–9% protein; 0.058% TRY) showed a higher susceptibility to convulsions than what was registered in animals fed a Quality Protein Maize (QPM)-based diet (8–9% protein; 0.1% TRY). It is concluded that low TRY concentration in the diet during development, produces lower rate of brain 5-HT synthesis, affecting development and maturation of GABAergic inhibitory cortical interneurons, with alteration of cortical excitability, contributing in part, to the increased susceptibility to convulsions, as shown in the experiments here reported. Special issue article in honor of Dr. Ricardo Tapia.     

Effects of isoflavones containing soy protein isolate compared with fish protein on serum lipids and susceptibility of low density lipoprotein and liver lipids to in vitro oxidation in hamsters

The effects of dietary soy protein isolate (SPI), ethanol-extracted SPI (E-SPI) low in isoflavones, and fish protein (FP) on the concentration of blood lipids and the susceptibility of low density lipoprotein (LDL) to copper-induced oxidation were compared in male golden Syrian hamsters fed a moderate hypercholesterolemic semi-purified diet for 10 weeks. SPI, E-SPI, and FP were incorporated into the isonitrogenous experimental diets as protein sources. The SPI group exhibited significantly lower serum total cholesterol concentration compared with the E-SPI group (P < 0.05) and the FP group (P < 0.01). Both the SPI and E-SPI groups showed lower LDL cholesterol (P < 0.001 and P < 0.05, respectively) and less LDL apolipoprotein B (P < 0.01) compared with the FP group. The distribution pattern of serum lipoprotein cholesterol fractions of the SPI and E-SPI groups were similar to each other, but different from that of the FP group. The lysine/arginine ratio of the three diets was significantly correlated with serum total cholesterol concentration (r = 0.462, P = 0.023). The resistance of LDL to copper-induced oxidation was greater in the SPI group than in the E-SPI and FP groups as assessed by the lower concentrations of thiobarbituric acid-reactive substances (TBARS) and the longer lag time required for the formation of conjugated dienes (P < 0.01). Livers of hamsters fed the FP diet had a higher amount of TBARS than those of hamsters fed SPI (P < 0.01) and E-SPI (P < 0.05) diets. The SPI diet showed sparing effects on alpha-tocopherol contents in both serum and liver. It seems likely that soy isoflavones protect the circulating and membrane lipids by sparing alpha-tocopherol and endogenous antioxidants.     

Metabolic effects of oral contraceptives in monkeys fed adequate protein & low proein diets

The effects of 2 oral contraceptives, Ovulen and Norlestrin, were studied in monkeys fed adequate protein and low protein diets. The experiment was carried out in parts. In the first one, the administration of contraceptives was cyclic and similar to that employed in human subjects. In the other experiments, the contraceptives were given continuously and an attempt was made to exaggerate the deleterious effects of the oral contraceptive on the liver by including small doses of a known hepatotoxic agent, aflatoxin (AT). In Experiment 1, 45 female monkeys were divided into 2 groups of 20 and 25 and received an adequate protein (16%) and low protein diet (4%) respectively. Each monkey was fed 1/5 of a tablet of Ovulen or Norlestrin orally for 3 weeks, and then administration was discontinued for 1 week. In Experiment 2, 35 female monkeys were divided into 7 groups of 5 each. All the animals recieved 4% protein diet. 5 groups were tube fed at the rate of 100 cal/kg body weight, while 2 groups were given diet ad libitum. Group I received the diet alone while groups II-V received 10 mcg AT, 25 mcg AT, 10 mcg AT plus 1/5 Ovulen tablets, and 25 mcg AT plus 1/5 Ovulen tablet respectively daily. Groups VI and VII received the diet ad libitum but were orally fed 75 mcg AT and 75 mcg AT plus 1/5 Ovulen tablet respectively. Serum glutamic-oxalacetic transaminase activity and alkaline phosphatase activity were studied at regular intervals after the administation of oral contraceptives in the experiments. Serum proteins and hemoglobin were also determined. Monkeys fed oral contraceptives showed increased serum glutamic-oxalacetic transaminase and alkaline phosphatase activities irrespective of the level of protein in the diet. Livers of animals receiving oral contraceptives were morphologically similar to the controls fed respective diets. The experiments were conducted for a period of almost 2 years.     

Food consumption and retention time in captive whooping cranes (Grus americana)

Food consumption, digesta retention time, and food preference were measured for captive whooping cranes fed pelleted diets. The basal commercial diet was compared to four mixtures containing 70% basal and 30% of one of four important winter foods for the whooping crane: blue crab (Callinectes sapidus), wolfberry fruit (Lycium carolinianum), live oak acorn (Quercus virginiana), or common Rangia clam (Rangia cuneata). Because captive birds would not eat whole foods, we were prevented from direct food preference tests. Food passed through the gut rapidly, with almost complete elimination within 7 hr. There was some indication that retention time was shorter for the low fiber and high ash and calcium clam diet. Cranes ate less wolfberry feed (g/day) than the other feeds, and all birds ate less wolfberry feed on the day it was first fed, compared to basal diet the previous day. Birds ate more low energy feed than high energy feed. Due to combined effects of low energy content, lower metabolizable energy coefficients, and reduced feed consumption, less energy was assimilated for study diets than basal diet. Apparent shorter retention times for some diets containing whooping crane foods may partly explain lower digestibilities and metabolizable energy of winter whooping crane foods compared to commercial crane diet. Zoo Biol 16:519–531, 1997. © 1997 Wiley-Liss, Inc.     

Accumulation of histidine, 3-methylhistidine, and homocarnosine in the brains of protein-calorie deficient monkeys

Abstract— Seventeen monkeys (M. nemestrina and M. fascicularis) aged 10 months to about 5 yr were divided into two groups and fed either an adequate protein diet (20% casein) or a low-protein diet (2% casein). The diets were supplied to the animals in restricted amount (200 g/animal in two daily rations). In one experiment, the malnourished animals were initially fed a diet containiing 8 per cent protein and the protein content of the diet was gradually reduced over a period of 9 months, to 2 per cent. After about 3 months on the 2 per cent protein diet, the malnourished monkeys showed growth failure, severe anorexia, peri-ocular oedema, tremors of the head and limbs, atrophy of several visceral organs, fatty liver, hypoalbuminaemia, and depressed serum levels of many essential amino acids with an elevation of the ratio of non-essential to essential amino acids. These features are consistent with protein-calorie malnutrition. Examination of the brains revealed significant alterations in the levels of glycerophosphoethanolamine (—40 per cent), glutamic acid (—25 per cent), histidine (+230 per cent), homocamosine (+185 per cent), 3-methyl-histidine (+147 per cent), lysine (+55 per cent), phenylalanine (+33 per cent) and tyrosine (+26 per cent) in comparison to findings on the well-fed monkeys. The possible implications of elevated cerebral contents of homocarnosine in malnourished monkeys are discussed in the light of several reported human cases in whom neurological disorders are associated with increased histidine-containing dipeptides in the brain, CSF, blood and urine.     

Effects of dietary amino acid l‐lysine on survival,growth and haemato‐biochemical parameters in Indian catfish,Heteropneustes fossilis (Bloch, 1974), fingerlings

An 8‐week feeding experiment was conducted to estimate the dietary lysine requirement of fingerling Indian catfish, Heteropneustes fossilis (total length = 6.35 ± 1.10 cm; weight = 4.70 ± 0.65 g) by feeding six isonitrogenous (400 g/kg CP) and isocaloric diets (17.90 kJ/g) containing six supplemental lysine levels ranging from 11.0 to 23.5 g/kg (diets I to VI, in incremental steps of 2.5 g/kg). Triplicate groups with 20 fish each were stocked in 75‐L circular continuous flow‐through troughs and fed experimental diets at 4% BW/day twice daily (08:00 and 18:00 h). Maximum live weight gain (304%), best‐feed conversion ratio (FCR, 1.46) and protein efficiency ratio (PER, 1.71) were obtained at 18.5 g/kg dietary lysine, beyond which these values showed a slight declining tendency. Best values for somatic and hematological indices were also obtained at this level. Significantly (p < .05) higher body protein and low carcass moisture and intermediate fat contents were noted in fish fed diets containing 18.5 g/kg lysine. The quadratic regression analyses of live weight gain, FCR, PER and body protein deposition (BPD) data indicated lysine requirements at 19.3, 18.8, 18.6 and 18.6 g/kg of dry diet, respectively. Based on these results, it is recommended that the H. fossilis diet should contain lysine at a level of 19.0 g/kg of dry diet, corresponding to 47.5 g/kg of dietary protein, for optimum growth and efficient feed utilization.     

Energy metabolism and protein balance in growing rats fed different levels of dietary fibre and protein

A study was performed to investigate the effect of different levels of dietary fibre (DF) and dietary protein on visceral organ size, digestibility, nitrogen balance and energy metabolism in rats. Thirty-six male Wistar rats, initial body weight about 76 g, were used in a factorial design consisting of three levels of DF (low, 100 g/kg DM; medium, 250 g/kg DM and high, 290 g/kg DM) and two levels of dietary protein (low, 120 g/kg DM and high, 223 g/kg DM). The added fibre source was soybean hulls and Danish fish meal was used as sole source of dietary protein. Measurements of gas-exchange were done on six rats (one group) while urine and faeces were collected individually. The ratio of food/empty body gain increased (P < 0.05) with increasing DF and decreasing levels of dietary protein. The weight of the digestive tract was larger (P < 0.05) in rats fed the high fibre diet than in those fed the low fibre diet. The digestibility of nutrients and energy decreased linearly with increasing level of soybean fibre (P < 0.05). An increased intake of DF was associated with a concomitant loss of protein and energy to faeces. The microbial degradation of NSP and other unabsorbed carbohydrates caused considerably changes in N metabolism of the colon. In rats fed the low protein diets increased levels of DF decreased N excretion in urine and increased N excretion in faeces, while the ratio of retained/digested protein remained constant. When rats were fed the high protein diet protein retention dropped in response to DF both absolute and relative to digested amount, indicating that energy intake could be a limiting factor. Heat production as a percentage of metabolizable energy (HP/ME) was higher (P < 0.05) in rats fed the low protein diet than in rats fed the high protein diet, but no significant difference was found among DF levels.     

饵料蛋白质水平对德国小蠊营养效应及氮代谢的影响

【目的】本研究旨在探究饵料蛋白质水平对德国小蠊Blattella germanica营养利用及氮代谢的影响,为蟑螂毒饵的研发提供新思路。【方法】采用标准重量分析法评估了取食4种不同蛋白质水平(5%, 25%, 45%和65%)饵料的德国小蠊雄成虫营养效率指数和氮利用率;利用分光光度法测定了取食不同蛋白水平饵料的德国小蠊雄成虫体内黄嘌呤氧化酶(xanthine oxidase, XOD)、谷草转氨酶(glutamic oxaloacetic transaminase, GOT)、谷丙转氨酶(glutamic pyruvic transaminase, GPT)活性及尿酸含量。【结果】取食65%蛋白质饵料组的德国小蠊雄成虫的相对取食量最高,而取食45%蛋白质饵料组的雄成虫食物利用率、食物转化率及相对生长率均显著高于取食5%和65%蛋白质饵料组的雄成虫。且德国小蠊雄成虫体内氮、粪便氮、氮消耗速率、氮排泄率、氮生成率、氮同化效率、黄嘌呤氧化酶活性和尿酸含量均随饵料蛋白质水平的提高而提高,但65%蛋白质饵料组氮利用率最低,45%蛋白质饵料组谷草转氨酶活性最高,25%和45%蛋白质饵料组谷丙转氨酶活性显著高于5%和65%蛋白质饵料组。【结论】适量蛋白质饵料有利于德国小蠊对食物及氮的利用,而高蛋白质含量条件下德国小蠊谷草转氨酶和谷丙转氨酶活性下降,说明高蛋白不利于德国小蠊利用食物,且增加其代谢负担。     

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.     

Effects of feeding low protein diets to piglets on plasma urea nitrogen, faecal ammonia nitrogen, the incidence of diarrhoea and performance after weaning

This study evaluated the effects of feeding pigs low protein (LP) diets for different lengths of time after weaning on indices of protein fermentation, the incidence of postweaning diarrhoea (PWD), growth performance, and total-tract apparent digestibility. Sixty weaner pigs weighing 6.1 +/- 0.13 kg (mean +/- SEM) were used in a completely randomised design having five treatments: (i) a high protein diet (HP, 243 g/kg CP) fed for 14 d after weaning (HP14); (ii) a low protein diet (LP, 173 g CP/kg) fed for 5 d after weaning (LP5); (iii) LP diet fed for 7 d after weaning (LP7); (iv) LP diet fed for 10 d after weaning (LP10), and (v) LP diet fed for 14 d after weaning (LP14). All diets were supplemented with lysine, methionine, tryptophan and threonine, with all LP diets additionally fortified with crystalline isoleucine and valine to conform to a proposed ideal amino acid (AA) pattern. A second-stage diet (215 g CP/kg) was fed to pigs at the conclusion of each treatment. None of the diets contained antimicrobial compounds. Feeding a LP diet, regardless of duration of feeding, decreased plasma urea nitrogen (p < 0.001) and faecal ammonia-nitrogen (p < 0.001) contents. Feeding a LP diet, irrespective of feeding duration, decreased the incidence of PWD at day 8 after weaning (p = 0.044), and pigs fed diets LP7, LP010 and LP14 had firmer faeces (p = 0.030, p = 0.047 and p = 0.007, respectively) between days 10 and 12 after weaning. Treatments LP5, LP7, LP10 and LP14 did not reduce (p > 0.05) growth performance up to 106 days after weaning compared to pigs fed the HP diet. Total-tract apparent digestibility of dry matter, energy and crude protein were similar (p > 0.05) between treatments. Our data suggest that feeding a LP diet, supplemented with AA to conform to an ideal AA pattern, for 7-10 days after weaning can reduce PWD in pigs fed antibiotic-free diets without compromising production.     

Negative effects of a low-quality protein diet on wound healing via modulation of the MMP2 activity in rats

Protein malnutrition is largely associated with a delay or failure of the healing process. However, the effect of dietary protein quality on wound healing is largely unknown. This study aimed to reveal the effect of dietary protein quality on wound healing and elucidate the regulatory mechanisms in a rat model of full-thickness cutaneous wounds. Rats were fed a normal diet for a week, and then they were divided into three groups that were fed the following diet for the experimental period: casein diet, gluten diet and gluten + lysine diet. The gluten diet significantly decreased body weight and wound healing compared with the casein diet, but this effect was reversed by supplementation with lysine. The numbers of leukocytes were significantly higher in the skin of the gluten group than those in the casein group. The wounded skin tissues of the gluten group showed lower amounts of collagen deposition compared with that in the casein group. Our results also showed that both matrix metalloproteinase (MMP) 2 activity and MMP14 mRNA levels were significantly increased in the skin of the gluten group, compared with the casein group. In summary, this study suggests low-quality protein diets have negative effects on wound healing via modulation of MMP2 activity in rats.     

Development of probiotic diets for the olive fly: evaluation of their effects on fly longevity and fecundity

One possible control strategy against the olive fly, Bactrocera oleae, the most serious olive crop pest, is the Sterile Insect Technique (SIT) application. However, a number of problems associated with this method remain that decrease the effectiveness of SIT, including the quality of reared insects. Taking the importance of the relationship between the olive fly and bacteria into consideration, the effects of probiotic diets enriched with Pseudomonas putida on B. oleae longevity and fecundity were evaluated. First, we found that the probiotic bacterium, P. putida, is conveyed from diets to the oesophageal bulb as well as to the fly midgut after feeding on the probiotic diet. Subsequently, B. oleae adults fed on either: (a) a standard full protein and sugar diet; (b) a sugar only diet; (c) a probiotic standard full protein and sugar diet; or (d) a probiotic sugar diet. Flies fed on probiotic diets were supplied with an inoculated gel containing P. putida; non‐inoculated gel was provided to the flies fed on non‐probiotic diets. B. oleae males and females that fed on sugar diets did not survive as long as those that fed on protein diets. A comparison of the longevity of adults fed on full diet and sugar with their respective probiotic diets revealed no significant difference. Males fed on the sugar only diet survived longer than males fed on probiotic sugar diet, and females fed on the full protein and sugar diet survived much longer than females fed on the full probiotic diet. As regarding fecundity, both full diets resulted in a higher number of eggs laid per female. Females fed on the probiotic sugar diet laid a higher number of eggs than females that fed on sugar only. The inoculated gel of the probiotic sugar diet contained a significantly higher quantity of leucine, isoleucine and proline than the non‐inoculated gel of the sugar only diet. The possible role of dietary bacteria in relation to functional aspects of olive fly physiology is discussed.     

Lupinus luteus,Vicia sativa and Lathyrus cicera as protein sources for piglets: ileal and total tract apparent digestibility of amino acids and antigenic effects

Twenty-four male piglets, weaned at 28 days of age, were used to measure the total and ileal digestibility and serum immune responses to dietary leguminous seeds. The experimental diets consisted of a control starter (C) and three other diets prepared by replacing 30% of the crude protein content of the C diet by the protein of Lupinus luteus (LL), Vicia sativa (VS) or Lathyrus cicera (LC). The total tract apparent digestibility (TTAD) of energy and crude protein (CP) was lowest (P<0.001) for the LC diet. Similarly TTAD of lysine, methionine and threonine were also lowest for the LC diet. The apparent ileal digestibility (AID) of lysine, methionine and threonine were lowest for the LC diet. AID of lysine and methionine was highest for the LL seeds (0.764 and 0.834, respectively) and lowest (P<0.05) for the LC seeds (only 0.454 and 0.420, respectively). Immunoblots of individual pig serum were made to detect both residual antigenic storage proteins of the seeds of each legume used and IgGs specific to those storage proteins. Antibodies against β-conglutin of L. luteus, vicilin of V. sativa and vicilin of L. cicera were detected 28 days after feeding the diet in the sera of piglets fed on the LL, VS or LC diets, respectively. Conversely, no storage protein was found in the serum of any piglet fed either on LL, VS or LC diets. The presence of antibodies against β-conglutin of lupine, vicilin of V. sativa and vicilin of L. cicera, respectively indicated an immune response in weaned piglets. The absence of residual antigenic proteins may be due to the digestive adaptation of the piglet to the legume-based diets. However, no direct relation between the differences in digestibility coefficients among the legume seeds and their antigenicity was established.     

The effect of peptide absorption on PepT1 gene expression and digestive system hormones in rainbow trout (Oncorhynchus mykiss)

The present study evaluates the effect of protein source (dipeptides, free amino acids, and intact protein) on development and growth of Salmonid fish alevin. Specifically, we follow the expression of oligopeptide transporter protein PepT1 in the intestine of rainbow trout (Oncorhynchus mykiss). Fish were fed exogenously one of four diets: three formulated (lysyl–glycine dipeptide supplemented diet — PP, free lysine and glycine supplemented diet — AA, control diet with no lysine — CON) or commercial starter (Aller Futura — AF). Fish increased mean body weight 8 fold with PP- and AA-supplemented diets resulting in significantly higher weight gain than fish fed CON. Statistical analysis revealed a significant increase in relative PepT1 expression of fish fed experimental diets. Immunohistochemical staining with PepT1 antibody showed the presence of the transporter protein in the brush border membrane of the proximal intestinal enterocytes of fish from all experimental groups. Leptin immunoreactivity occurred not only in the gastric glands but also in proximal intestine and pyloric caeca of fish fed PP, AA and AF diets. Leptin immunoreactivity was also observed in hepatocyte cytoplasm and pancreatic acinar cells. Gastrin/CCK immunoreactive cells were present in the proximal intestine and pyloric caeca.     

Coupling diet quality and Bowman-Birk and Kunitz-type soybean proteinase inhibitor effectiveness to Diatraea saccharalis development and mortality

We used bioassays to investigate the effect of Bowman‐Birk and Kunitz‐type soybean proteinase inhibitors on two artificial diets (diets 1 and 2) which are commonly used to feed laboratory colonies of larvae of the moth Diatraea saccharalis, monitoring food intake and utilization, and larval development and mortality. Diet 1 was less nutritious, with a low protein content and reduced mineral and essential amino acid (e.g., cysteine, lysine, and methionine) content, while diet 2 was richer and more complete. When proteinase inhibitors were incorporated into the artificial diets, the effects on larval development were significantly greater for those larvae fed diet 1, with the chronic ingestion of proteinase inhibitors reducing the level of trypsin‐like activity in the midgut of larvae fed this diet. Larvae fed diet 2 also showed a reduced level of tryptic activity in the midgut, but this was less marked than for diet 1. These results indicate that despite their inhibitory effect on midgut enzymes, the effectiveness of proteinase inhibitors is directly dependent on the quality of the diet. The different effects seen on insect biology when proteinase inhibitors are added to rich or poor diets suggests that the role of anti‐nutritional proteins in the control of insects might not be adequately addressed by bioassays based on the incorporation of inhibitors into artificial diets.