Effects of low dietary protein on the metabolites and microbial communities in the caecal digesta of piglets

Thirty-six healthy piglets (weighing 10 ± 1 kg; three animals per pen) were randomly allocated to two treatments: (i) a low protein diet (14% crude protein [CP]) supplemented with lysine, methionine, threonine and tryptophan (Group LP) and (ii) a normal protein diet (20% CP, Group NP), resulting in six replicate pens per treatment. One piglet from each pen was slaughtered at days 10, 25 and 45 of the experiment. For the whole experimental period of 45 d, Group LP had lower feed intake and daily gain and a higher feed-to-gain ratio compared with Group NP. At day 10, no effects on measured caecum metabolites were observed, but at days 25 and 45 in Group LP the concentration of ammonia-N, cadaverine, branched chain fatty acids and acetate were reduced. This was also true for the concentration of short chain fatty acids at day 45. The results of denaturing gradient gel electrophoresis showed that microbial diversity in Group LP was less abundant at day 25, but there was no difference at days 10 and 45. An unweighted pair group mean average analysis showed that the similarities were lower between Groups LP and NP at day 10 and higher at days 25 and 45. Quantitation results indicated that the numbers of Firmicutes and Clostridium cluster IV were lower in Group LP than in Group NP at day 25, but there were no differences at days 10 and 45. In conclusion, the low protein diet markedly reduced the metabolites of protein and carbohydrate fermentation and altered microbial communities in the caecal digesta of piglets.     

Na<Superscript>+</Superscript>/K<Superscript>+</Superscript>-ATPase stabilization by Hsp70 in the outer stripe of the outer medulla in rats during recovery from a low-protein diet

A low-protein (LP) diet induces injury from energy depletion in renal epithelial cells. Overexpression of heat-shock proteins has been implicated in the restoration of the cytoskeletal anchorage of Na⁺/K⁺-ATPase. We tested if Hsp70 stabilizes renal Na⁺/K⁺-ATPase attachment to the cytoskeleton from the cortex and the outer stripe of the outer medulla (OSOM) in rats during recovery from a LP diet. Rats were fed with a LP diet (8% protein) for 14 days, and then the rats were recovered with a 24% protein (RP) diet. The control group received a 24% protein (NP) diet. Increased Na⁺/K⁺-ATPase dissociation was demonstrated in soluble fraction from OSOM with lower ATP content as a result of LP diet vs NP. Meanwhile, decreased Hsp70 levels in the same fraction were shown. Translocation of Hsp70 to the cytoskeletal injured fraction associated with stabilization of Na⁺/K⁺-ATPase was shown in OSOM from LP after in vitro co-incubation of the cytoskeletal fraction of LP and non-cytoskeletal fraction of RP. These effects were abolished by the addition of the anti-Hsp70 antibody. Absence of Na⁺/K⁺-ATPase detachment from its cytoskeletal anchorage was demonstrated in proximal duct segments from cortex in LP. Co-immunoprecipitation showed that the amount of Na⁺/K⁺-ATPase co-precipitating with Hsp70 increased in the OSOM as a result of the LP diet. In the cortex tissues from rats fed the LP and the RP diet, the interaction of both proteins were similar to the control groups. Our results indicate that Hsp70 has a critical role in protecting the integrity of the cytoskeletal anchorage of Na⁺/K⁺-ATPase during recovery from ATP-depleted injury resulting from LP in OSOM. Portions of this study were presented in abstract form at the World Congress of Nephrology in Rio de Janeiro, Brasil. April 21–25, 2007.     

Effects of dietary l-lysine intake on the intestinal mucosa and expression of CAT genes in weaned piglets

The objective of this study was to evaluate effects of dietary l-lysine on the intestinal mucosa and expression of cationic amino acid transporters (CAT) in weaned piglets. Twenty-eight piglets weaned at 21 days of age (Duroc × Landrace × Yorkshire; 6.51 ± 0.65 kg body weight) were assigned randomly into one of the four groups: Zein + LYS (zein-based diet + 1.35 % supplemental lysine), Zein ? LYS (zein-based diet), NF (nitrogen-free diet), and CON (basal diet). The experiment lasted for 3 weeks, during which food intake and body weight were recorded. At the end of the trial, blood was collected from the jugular vein of all pigs, followed by their euthanasia. Dietary supplementation with lysine enhanced villus height and crypt depth in the jejunum (P < 0.05). Jejunal mRNA levels for the b^0,+-AT, y⁺LAT1 and CAT1 genes were greater (P < 0.05) in the Zein + LYS group than in the control, and the opposite was observed for CAT1. Dietary content of lysine differentially affected intestinal CAT expression to modulate absorption of lysine and other basic amino acids. Thus, transport of these nutrients is a key regulatory step in utilization of dietary protein by growing pigs and lysine in the diet influences the expression of amino acid transporters in the small intestine.     

Dietary branched-chain amino acids suppress the expression of pancreatic amylase mRNA in rats

Regulators for pancreatic amylase were examined. Rats were fed ad libitum a 20% amino acid (AA) mixture diet (Con), a 60% AA diet (HA), a branched-chain amino acid (BCAA)-rich diet (BC), or a diet supplemented with AA other than BCAA (OA) for 7 d, or fed the Con, HA, BC diets or diets supplemented with individual BCAA. Activity and mRNA levels of pancreatic amylase in the BC and HA groups were lower than those in the Con and OA groups. Leucine and isoleucine contributed to these effects of the BC diet. The mRNA levels correlated with individual pancreatic BCAA concentrations but not with plasma insulin level. In conclusion, dietary BCAA, especially leucine and isoleucine, may reduce amylase mRNA and activity in rats.     

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.     

Effect of Long-term Fluoride Exposure on Growth, Nutrient Utilization and Fluoride Kinetics of Calves Fed Graded Levels of Dietary Protein

In order to assess the influence of dietary protein levels on the fluoride (F) bioavailability, 30 crossbred calves (6-8 months; approximately 104 kg BW) initially exposed to different dietary protein levels were allotted into six groups in a 3?×?2 factorial design. The factors included three different levels of protein viz. normal (100%; NP), low (75%; LP), and high (125%; HP) as per Kearl recommendations besides two levels of supplemental fluorine (as sodium fluoride) at 0 or 200 mg/kg diet. The animals were fed on the respective concentrate mixture and wheat straw for 210 days. A metabolism trial was conducted at 200 days post-feeding to study digestibility, plane of nutrition, and nutrient balances. The final body weight at the end of 210 days was lower (p?<?0.01) in animals fed 200 mg/kg F (164.2?±?8.92 kg) compared to those fed no F (200.7?±?8.05 kg). Calves on LP diets attained lower (p?<?0.05) average daily gain in comparison to NP or HP fed calves. The F-supplemented calves exhibited lower (p?<?0.01) voluntary feed intake than their non-supplemented control. The digestibility of proximate nutrients other than ether extract exhibited higher (p?<?0.01) values in F-fed calves attributable chiefly to reduced consumption of dry matter. The calves fed extra F retained lower mean daily nitrogen; calcium, and phosphorus compared to the calves fed no F. The mean daily intake, excretion, and retention of F were higher (p?<?0.01) in the F-supplemented calves. A significant (p?<?0.01) interaction between protein levels and F was evident in the urinary excretion of F; calves on LP diet exhibiting lower urinary excretion. Consequently, the bioavailability of F tended to be higher on LP than NP or HP diets. From the results, it is concluded that protein levels in the diet do not impart significant influence on susceptibility to fluorosis in crossbred calves. However, the bioavailability of F tended to increase on diets low in protein.     

Ileal amino acids digestibility of sorghum in weaned piglets and growing pigs

The objective of the study was to determine the coefficients of ileal apparent digestibility (CIAD) of sorghum protein and amino acids (AA) in weaned piglets and growing pigs. Digestibility coefficients were estimated using the regression and difference methods for the weaned piglets; and the direct and difference methods for the growing pigs. To test the hypothesis that CP and AA digestibility of sorghum is lower in weaned piglets than in growing pigs, two experiments were conducted. In experiment one, 20 weaned piglets were fitted with a 'T' cannula at 21 days of age and were fed for 2 weeks one of five dietary treatments: a reference or control diet providing 200 g of CP/kg from casein (C) as the sole protein source, and four casein-sorghum (C-S) diets kept isoproteic to C by the appropriate adjustment of C and maize starch proportions; the amount of sorghum (S) in these diets was 135, 307, 460 and 614 g/kg. In experiment 2, fifteen castrated pigs weighing 57.8 ± 2.8 kg were used and randomly allotted to one of three dietary treatments: a reference casein-maize starch diet containing C as the sole protein source, a C-S diet, both diets containing 160 g of CP/kg, and a fortified S diet containing 68 g of CP/kg. In piglets the CIAD for CP and AA decreased linearly (P < 0.05) as the amount of S in the diet increased. The average ileal digestibility of AA from C was 0.858 ± 0.111, and decreased to 0.663 ± 0.191 at the higher S level. The CIAD estimated using the regression or difference methods were similar for leucine, cysteine, glutamic acid, serine, alanine and tyrosine, and different for the other AA. In growing pigs the CIAD of protein and AA (except alanine and cysteine) were similar (P > 0.05) for the C and the C-S diets, but higher (P < 0.05) than those for the S diet. The CIAD for S obtained by the difference method were higher (P < 0.05) than those obtained using the direct method, except for lysine, isoleucine, valine, methionine, threonine and cysteine. The results indicate that except for lysine and cysteine, growing pigs' ability to digest AA and protein is superior than weaned piglets.     

Atlantic salmon (Salmo salar) protein hydrolysate in diets for weaning piglets ─ effect on growth performance,intestinal morphometry and microbiota composition

Salmon protein hydrolysates (SPH) from two different rest raw materials were evaluated in diets for weaning piglets. Four experimental diets were included in the study: a diet based on plant protein with soy protein as the main protein source (Diet PP), a diet based on fishmeal in exchange for soy protein (Diet FM) and two diets in which different SPH replaced fishmeal in the FM diet. The experimental diets were fed to piglets from the day of weaning until 32 d postweaning. In addition to the record of performance data, an intestinal sampling for mucosal morphometry and microbiota 16S rRNA gene sequencing were performed at day 11 on a subset of the animals. The duodenal villi absorption area was significantly larger in piglets receiving Diets SPH compared with Diet PP (p < 0.02). A significant positive correlation between duodenal villi height and average daily gain during the first 11 d postweaning was detected. Only small differences in intestinal microbiota community and no differences in growth performance were detected between the experimental diets. To conclude, SPH seem to be an interesting novel protein source in weanling piglets.     

Endogenous ileal losses of nitrogen and amino acids in pigs and piglets fed graded levels of casein

Abstract

In order to determine ileal losses of nitrogen (N) and amino acids (AA) and the coefficients of apparent and true ileal digestibility (AID, TID) of N and AA from casein in piglets and pigs, two experiments were conducted. In Experiment 1, 24 piglets were used. The piglets were weaned at 17 days of age, weighing 6.4 kg and cannulated at terminal ileum. Ileal digesta was collected at 28 – 29 and 35 – 36 days of age in period 1 and 2, respectively. Feed intake was 150 and 300 g · d^?1 during the first and second period. In Experiment 2, 16 castrates weighing 52.5 kg and cannulated at terminal ileum were used. The intake level of digestible energy was 2.5 times their maintenance requirement. The experiment lasted 7 days and ileal digesta was collected on day 6 – 7. Treatments consisted of four levels of N from casein: 8, 16, 24 and 32 g N · kg^?1 feed, respectively. Results showed that N level did not increase N or AA ileal losses. In piglets, N and AA ileal losses were similar between periods, except for period 2, where losses per kg DMI were about 47 and 64% higher for glycine and proline, respectively (p < 0.05). When ileal losses from pigs and piglets were compared, piglets had higher (p < 0.05) ileal losses of N and AA (excepted glutamic acid and alanine). A lower (p < 0.05) AID was observed in piglets in period 2 for N, methionine, glutamic acid, glycine and proline. With exception of glycine in pigs, all values for TID of N and AA of casein were superior to 0.90. Piglets had higher TID of N, leucine, isoleucine, valine and phenylalanine. These results showed that piglets have higher ileal losses than pigs.     

Amino acids modulates the intestinal proteome associated with immune and stress response in weaning pig

The objective of this study was to investigate the effects of free amino acids supplementation to protein restricted diet on the intestinal morphology and proteome composition in weaning pigs. Weanling piglets were randomly fed one of the three diets including a corn-soybean based control diet and two lower protein diets with or without free amino acids supplementation for 2 weeks. The jejunum samples of piglets were collected for morphology and proteome analysis. Compared with the control diet, the protein restricted diet had a significant lower average daily gain and higher feed conversion rate. Free amino acids supplementation to the protein restricted diet significantly improved average daily gain and higher feed conversion rate, compared with the protein restricted diet. The villous height in pigs fed the protein restricted diet was lower than that of the control and free amino acids diet. Using two-dimensional gel electrophoresis and mass spectrometry, we identified 16 differentially expressed protein spots in the jejunum of the weaning piglet. These proteins were related to stress and immune response, the metabolism of carbohydrates and lipids, and tissue structure. Based on the proteome and ELISA analysis, free amino acids diet significantly down-regulated the jejunal expression of stress protein heat shock 60 kDa protein. Our results indicated that amino acids supplementation to the protein restricted diet could enhance weight gain and feed efficiency in weanling pigs through improving intestinal nutrient absorption and transportation, gut health, and mucosal immunity.     

Interaction and imbalance between indispensable amino acids in young piglets

Lowering protein level in diets for piglets urge to have knowledge on the piglet’s requirements for essential amino acids (AA) and their interactions. The present studies aimed to determine the interaction between the dietary level of valine (Val) and tryptophan (Trp) and the effect of AA imbalance at two levels of dietary Val on the growth performance of post-weaning piglets. In Experiment 1 (duration 4 weeks), the effects of supplementation of free l-Val (1.0 g/kg) and/or l-Trp (0.5 g/kg) in a low-CP diet (CP 17.7%), marginal in Trp and Val, was studied in a 2×2 factorial design and using an additional reference treatment (CP 19.5%). In Experiment 2 (duration 5 weeks), the influence of a stepwise increase in excess supply of isoleucine (Ile), histidine (His) and leucine (Leu), up to 10, 10% and 30% relative to their requirement values respectively, was evaluated at 60% or 70% standardized ileal digestible (SID) Val relative to SID lysine, using a 3×2 factorial design. In Experiment 1, over the whole experimental period, feed intake (FI) was affected by dietary Trp level (P<0.05) and feed conversion ratio (FCR) by both the level of Trp and Val in the diet (both P<0.05). Increasing Trp level increased FI and decreased FCR while increasing dietary Val level reduced FI and increased FCR. For BW gain (BWG), there was an interaction between dietary level of Trp and Val (P<0.05). Valine supplementation decreased BWG using a diet marginal in Trp, whereas it increased BWG when using a Trp sufficient diet. Piglets fed the low-CP diet with adequate levels of Val and Trp showed at least same performance compared to piglets fed the high CP reference diet. In Experiment 2, increasing dietary Val improved FI and BWG (P<0.001) and tended to improve FCR. Dietary AA excess for Ile, His and Leu reduced FI and BWG (P<0.05) and only affected FCR (P<0.01) in the 1^st week of the study. Dietary level of Val and AA excess did not show interactive effects, except for FCR over the final 2 weeks of the study (P<0.05). In conclusion, an interaction exists between dietary supply of Val and Trp on the zootechnical performance of post-weaning piglets and dietary AA excess for Ile, Leu and His, reduces growth performance of piglets in low-protein diets, independent of the dietary level of Val.     

Oral administration of MSG increases expression of glutamate receptors and transporters in the gastrointestinal tract of young piglets

Glutamate receptors and transporters, including T1R1 and T1R3 (taste receptor 1, subtypes 1 and 3), mGluRs (metabotropic glutamate receptors), EAAC-1 (excitatory amino acid carrier-1), GLAST-1 (glutamate-aspartate transporter-1), and GLT-1 (glutamate transporter-1), are expressed in the gastrointestinal tract. This study determined effects of oral administration of monosodium glutamate [MSG; 0, 0.06, 0.5, or 1 g/kg body weight (BW)/day] for 21 days on expression of glutamate receptors and transporters in the stomach and jejunum of sow-reared piglets. Both mRNA and protein levels for gastric T1R1, T1R3, mGluR1, mGluR4, EAAT1, EAAT2, EAAT3, and EAAT4 and mRNA levels for jejunal T1R1, T1R3, EAAT1, EAAT2, EAAT3 and EAAT4 were increased (P < 0.05) by MSG supplementation. Among all groups, mRNA levels for gastric EAAT1, EAAT2, EAAT3, and EAAT4 were highest (P < 0.05) in piglets receiving 1 g MSG/kg BW/day. EAAT1 and EAAT2 mRNA levels in the stomach and jejunum of piglets receiving 0.5 g MSG/kg BW/day, as well as jejunal EAAT3 and EAAT4 mRNA levels in piglets receiving 1 g MSG/kg BW/day, were higher (P < 0.05) than those in the control and in piglets receiving 0.06 g MSG/kg BW/day. Furthermore, protein levels for jejunal T1R1 and EAAT3 were higher (P < 0.05) in piglets receiving 1 g MSG/kg BW/day than those in the control and in piglets receiving 0.06 g MSG/kg BW/day. Collectively, these findings indicate that dietary MSG may beneficially stimulate glutamate signaling and sensing in the stomach and jejunum of young pigs, as well as their gastrointestinal function.     

Insulin and branched-chain amino acid depletion during mouse preimplantation embryo culture programmes body weight gain and raised blood pressure during early postnatal life

Mouse maternal low protein diet exclusively during preimplantation development (Emb-LPD) is sufficient to programme altered growth and cardiovascular dysfunction in offspring. Here, we use an in vitro model comprising preimplantation culture in medium depleted in insulin and branched-chain amino acids (BCAA), two proposed embryo programming inductive factors from Emb-LPD studies, to examine the consequences for blastocyst organisation and, after embryo transfer (ET), postnatal disease origin. Two-cell embryos were cultured to blastocyst stage in defined KSOM medium supplemented with four combinations of insulin and BCAA concentrations. Control medium contained serum insulin and uterine luminal fluid amino acid concentrations (including BCAA) found in control mothers from the maternal diet model (N-insulin + N-bcaa). Experimental medium (three groups) contained 50% reduction in insulin and/or BCAA (L-insulin + N-bcaa, N-insulin + L-bcaa, and L-insulin + N-bcaa). Lineage-specific cell numbers of resultant blastocysts were not affected by treatment. Following ET, a combined depletion of insulin and BCAA during embryo culture induced a non sex-specific increase in birth weight and weight gain during early postnatal life. Furthermore, male offspring displayed relative hypertension and female offspring reduced heart/body weight, both characteristics of Emb-LPD offspring. Combined depletion of metabolites also resulted in a strong positive correlation between body weight and glucose metabolism that was absent in the control group. Our results support the notion that composition of preimplantation culture medium can programme development and associate with disease origin affecting postnatal growth and cardiovascular phenotypes and implicate two important nutritional mediators in the inductive mechanism. Our data also have implications for human assisted reproductive treatment (ART) practice.     

Triploid Atlantic salmon Salmo salar have a higher dietary phosphorus requirement for bone mineralization during early development

The effect of a dietary phosphorus regime in freshwater on vertebra bone mineralization was assessed in diploid and triploid Atlantic salmon, Salmo salar. Fish were fed either a low phosphorus (LP) diet containing 10.5 g kg⁻¹ total phosphorus or a normal phosphorus (NP) diet containing 17.4 g kg⁻¹ total phosphorus from ∼3 to ∼65 g (day 126) in body weight. Two further groups were fed the NP diet from ∼3 g in body weight, but were then switched to the LP diet after 38 (∼10 g in body weight) or 77 (∼30 g in body weight) days. Growth, vertebral ash content (% ash) and radiologically detectable vertebra pathologies were assessed. Triploids were initially smaller than diploids, and again on day 77, but there was no ploidy effect on days 38 or 126. Vertebral ash content increased with increasing body size and those fish fed the NP diet had higher vertebral ash content than those groups fed the LP diet during the intervening time period, but this diet effect became less apparent as fish grew, with all groups having relatively equal vertebral ash content at termination. In general, triploids had lower vertebral ash content than diploids on day 38 and this was most evident in the group fed the LP diet. On day 77, those triploids fed the LP diet during the intervening time period had lower vertebral ash content than diploids. At termination on day 126, the triploids had the same vertebral ash content as diploids, irrespective of diet. There was a ploidy × diet interaction on vertebral deformities, with triploids having higher prevalences of fish with ≥1 deformed vertebra in all dietary groups except continuous NP. In conclusion, between days 0 and 77 (3–30 g body size), triploids required more dietary phosphorus than diploids in order to maintain similar vertebral ash content. A possible link between phosphorus feeding history and phosphorus demand is also discussed.     

Determination of standardized ileal crude protein and amino acid digestibilities in protein supplements for piglets

The objective of the study was to determine standardized ileal digestibilities (SID) of crude protein (CP) and amino acids (AA) in six ingredients commonly used in weanling pigs diets. The ingredients consisted of extruded soybeans (SBe), high-protein soybean meal (SBMhp), soy protein concentrate (SPC), hydrolyzed wheat gluten (WGh), conventional fish meal 1 (FM1) and extracted fish meal 2 (FM2e). Each assay feed ingredient was added to a purified cornstarch-based basal diet supplemented with casein and crystalline AA, and SID of CP and AA of assay ingredients were estimated using the difference method. A total of 12 3-week-old barrows were surgically fitted with T-cannulas at the distal ileum. The piglets were allocated to four simultaneous 3 × 3 Latin-square designs with three animals and three periods each, resulting in six observations per assay diet. After 3 to 5 days recovery from surgery, each assay diet was fed at a level of 30 g/kg body weight. Each experimental period consisted of 5 days for adaptation to the assay diets and 2 days for ileal digesta collection. The SID of CP, Lys, Met, Thr and Trp were 73%, 78%, 76%, 66% and 71% in SBe; 80%, 84%, 87%, 75% and 81% in SBMhp; 86%, 89%, 89%, 78% and 83% in SPC; 87%, 60%, 88%, 76% and 79% in WGh; 87%, 92%, 94%, 86% and 86% in FM1; and 79%, 86%, 89%, 80% and 74% in FM2e, respectively. The greatest SID of indispensable AA were observed for FM1 and SPC (SID 85% for most indispensable AA), followed by WGh, FM2e and SBMhp (SID 80% for most indispensable AA) and the smallest SID were obtained for SBe (SID < 80% for most indispensable AA). The SID of CP and indispensable AA in both types of fish meal, SBMhp and WGh were similar to SPC (P = 0.063 to 0.855), except for Arg (P = 0.010) and Lys (P = 0.001) in WGh, and Phe (P = 0.044) and Trp (P = 0.037) in FM2e. The SID of CP and indispensable AA were smaller in SBe compared with SPC (P < 0.001 to P = 0.017), except for Lys (P = 0.136). The SID of CP and indispensable AA were consistently smaller in FM2e compared with FM1 with significant differences for CP (P = 0.035), Phe (P = 0.028) and Trp (P = 0.008). Digestibility values measured in the present study can be used to formulate diets for piglets based on standardized ileal digestible contents of CP and AA.     

Effects of dietary protein and lipid levels on growth and feed utilization of wild‐caught striped sea bream,Lithognathus mormyrus

A feeding trial was carried out to determine the effects of dietary protein and lipid levels on the growth performance and feed utilization of wild‐caught striped sea bream (Lithognathus mormyrus). The experimental fish were collected from a local lagoon (Çardak Lagoon, Çanakkale, Turkey), transferred to the Marine Net Cage Unit and fed by hand to apparent satiation with a commercial sea bream feed (Biomar; 42% crude protein, 16% crude lipid). Approximately 4 weeks were needed to acclimate the fish to farming conditions. No pathological signs were observed and no fish losses occurred during the adaptation period. For the test trials four test diets with different levels of protein and lipid were formulated [low protein and low lipid (LP:LL), low protein and high lipid (LP:HL), high protein and low lipid (HP:LL), and high protein and high lipid (HP:HL)] and fed to L. mormyrus (mean weight 85.0 ± 4.6 g SEM) in the net cages (Ø 2 m, depth 2.5 m) for 60 days. During the experiment water temperature varied between 21.1 and 26.4°C; dissolved oxygen 8.4–9.6 mg L^?1; pH 7.2–8.6; and salinity 23.3–25.6‰. Growth performances of fish fed high protein diets were higher compared to fish fed low protein diets, irrespective of the dietary lipid level (P < 0.05). Feed conversion ratio (FCR) and protein efficiency ratio (PER) were not influenced by dietary protein or lipid levels (P > 0.05). Preliminary results indicate that striped sea bream can be easily adapted to farming conditions in net cages, and that a diet containing 50% crude protein and 15% crude lipid (HP:LL) levels with 23.0 g protein MJ^?1 gross energy of protein/energy ratio would be suitable for striped sea bream growth.     

Protein deficiency attenuates the effects of alloxan on insulin secretion and glucose homeostasis in rats.

We have investigated the effect of alloxan on insulin secretion and glucose homeostasis in rats maintained on a 17% protein (normal protein, NP) or 6% protein (low protein, LP) diet from weaning (21 days old) to adulthood (90 days old). The incidence of alloxan diabetes was higher in the NP (3.5 times) than in the LP group. During an oral glucose tolerance test, the area under serum glucose curve was lower in LP (57%) than in NP rats while there were no differences between the two groups in the area under serum insulin curve. The serum glucose disappearance rate (Kitt) after exogenous insulin administration was higher in LP (50%) than in NP rats. In pancreatic islets isolated from rats not injected with alloxan, acute exposure to alloxan (0.05 mmol/L) reduced the glucose- or arginine-stimulated insulin secretion of NP islets by 78% and 56%, respectively, whereas for islets from LP rats, the reduction was 47% and 17% in the presence of glucose and arginine, respectively. Alloxan treatment reduced the glucose oxidation in islets from LP rats to a lesser extent than in NP islets (23% vs. 56%). In conclusion, alloxan was less effective in producing hyperglycemia in rats fed a low protein diet than in normal diet rats. This effect is attributable to an increased peripheral sensivity to insulin in addition to a better preservation of glucose oxidation and insulin secretion in islets from rats fed a low protein diet.     

Modelling of sulphur amino acid requirements and nitrogen endogenous losses in kittens

ABSTRACT

The objective of this study was to estimate the sulphur amino acid (methionine + cystine) requirements and nitrogen endogenous losses in kittens aged 150 to 240 d. Thirty-six cats were distributed in six treatments (six cats per treatment) consisting of different concentrations of methionine + cystine (M + C): T1, 6.5 g/kg; T2, 8.8 g/kg; T3, 11.3 g/kg; T4, 13.6 g/kg; T5, 16.0 g/kg; and control, 6.5 g/kg. Diets were formulated by serial dilution of T5 (a diet relatively deficient in M + C but containing high protein concentrations) with a minimal nitrogen diet (MND). Thus, crude protein and amino acid concentrations in diets T1–T5 decreased by the same factor. The control diet was the T1 diet supplemented with adequate concentrations of M + C (6.5 g/kg; 8.8 g/kg; 11.3 g/kg; 13.6 g/kg and 16.0 g/kg). All diets were based on ingredients commonly used in extruded cat diets. Digestibility assays were performed for the determination of nitrogen balance. Nitrogen intake (NI) and nitrogen excretion (NEX) results data were fitted with an exponential equation to estimate nitrogen maintenance requirement (NMR), theoretical maximum for daily nitrogen retention (NR_maxT), and protein quality (b). M + C requirements were calculated from the limiting amino acid intake (LAAI) equation assuming a nitrogen retention of 45 to 65% NR_maxT. The NMR of kittens aged 150, 195, and 240 d was estimated at 595, 559, and 455 mg/kg body weight (BW)^0.67 per day, respectively, and M + C requirements were estimated at 517, 664, and 301 mg/kg BW^0.67 per day, respectively.     

Oct-1 functions as a transactivator in the hormonal induction of β-casein gene expression

An adverse environmental experience of the growing fetus leads to permanent changes in the structure and contractile function of the heart; however, the mechanisms are incompletely understood. To examine if a maternal low protein (LP) diet can modulate the gene and protein expression of the Ca²⁺-cycling proteins in the neonatal heart, we employed a rat model in which pregnant dams were fed diets containing either 180 (normal) or 90 g (low) casein/kg diet for 2 weeks before mating and throughout pregnancy. A significant reduction in the L-type Ca²⁺-channel mRNA level in the LP group was detected at 1, 7, and 14 days of age. Although ryanodine receptor (RyR) mRNA levels progressively declined in the aging heart in both groups, the RyR mRNA levels were consistently higher in the LP group. A reduction in RyR protein content was seen only in the hearts of the LP group at 7 days of age. The Na⁺-Ca²⁺-exchanger (NCX) mRNA level was also markedly increased at all ages. Although an increase in sarco(endo)plasmic reticulum ATPase 2a (SERCA) 2a mRNA was only detected in the LP group at 7 days of age, corresponding protein level was depressed. On the other hand, an initial decrease (at 1 day of age) followed by an increase (at 14 and 28 days of age) in phospholamban (PLB) mRNA levels was detected. Although PLB protein level was also depressed at 1 day of age in the LP group, a marked increase was seen at 7 days of age. Moreover, the ratio of serine 16 and threonine 17 phosphorylated PLB to non-phosphorylated PLB was reduced at 7 days of age in the hearts of offspring of the LP group. These data suggest that maternal LP diet can induce alterations in the gene expression and protein levels of the Ca²⁺-cycling proteins in the neonatal heart.     

甘露寡糖对断奶仔猪肠道主要菌群的影响

选择健康的 35日龄断奶仔猪 4 8头 ,随机分为两组 ,每组 3圈 ,每圈 8头。一组为含 0 .5 %甘露寡糠 +基础日粮 ,另一组为基础日粮。试验开始第 7天 ,每组各随机选 6头仔猪 ,麻醉后剖腹取肠道内容物以测定盲肠和结肠大肠杆菌、乳酸杆菌及双歧杆菌浓度和 p H。试验结果表明 ,与对照组相比 ,甘露寡糖可以显著降低盲肠、结肠大肠杆菌浓度 (P<0 .0 5 ) ;同时显著提高盲肠乳酸杆菌和双歧杆菌浓度 (P<0 .0 5 ) ,但对结肠乳酸杆菌和双歧杆菌数影响不显著 (P>0 .0 5 )