HP Diet Research Articles

Limited and excess dietary protein during gestation affects growth and compositional traits in gilts and impairs offspring fetal growth1,2

The aim of this study was to investigate whether dietary protein intake during gestation less than or greater than recommendations affects gilts growth and body composition, gestation outcome, and colostrum composition. German Landrace gilts were fed gestation diets (13.7 MJ of ME/kg) containing a low (n = 18; LP, 6.5% CP), an adequate (n = 20; AP, 12.1%), or a high (n = 16; HP, 30%) protein content corresponding to a protein:carbohydrate ratio of 1:10.4, 1:5, and 1:1.3, respectively, from mating until farrowing. Gilts were inseminated by semen of pure German Landrace boars and induced to farrow at 114 d postcoitum (dpc; Exp. 1). Energy and protein intake during gestation were 33.3, 34.4, and 35.8 MJ of ME/d (P < 0.001) and 160, 328, and 768 g/d, respectively, in LP, AP, and HP gilts (P < 0.001). From insemination to 109 dpc, BW gain was least in LP (42.1 kg), intermediate in HP (63.1 kg), and greatest in AP gilts (68.3 kg), whereas increase of backfat thickness was least in gilts fed the HP diet compared with LP and AP diets (3.8, 5.1, 5.0 mm; P = 0.01). Litter size, % stillborn piglets, and mummies were unaffected (P > 0.28) by the gestation diet. Total litter weight tended to be less in the offspring of LP and HP gilts (14.67, 13.77 vs. 15.96 kg; P = 0.07), and the percentage of male piglets was greater in litters of HP gilts (59.4%; P < 0.01). In piglets originating from LP and HP gilts, individual birth weight was less (1.20, 1.21 vs. 1.40 kg; P = 0.001) and birth weight/crown-rump length ratio was reduced (45.3, 46.4 vs. 50.7 g/cm; P = 0.003). Colostrum fat (7.8, 7.4 vs. 8.1%) and lactose concentrations (2.2, 2.1 vs. 2.6%) tended to be reduced in LP and HP gilts (P = 0.10). In Exp. 2, 28 gilts (LP, 10; AP, 9; HP, 9) were treated as in Exp. 1 but slaughtered at 64 dpc. At 64 dpc, LP gilts were 7% lighter than AP gilts (P = 0.03), whereas HP gilts were similar to AP gilts. Body composition was markedly altered in response to LP and HP feeding with less lean (P < 0.01) and greater fat content (P = 0.02 to 0.04) in LP and less fat content (P = 0.02 to 0.04) in HP gilts. Fetal litter weight and number, and embryonic survival at 64 dpc were not affected by the diets. These results indicated that gestation diets containing protein at 50 and 250% of recommendations and differing in protein:carbohydrate ratio led to marked changes in protein and fat metabolism in gilts resulting in fetal growth retardation of 15%, which mainly occurred during the second half of gestation.

Intrauterine growth restriction and postnatal high-protein diet affect the kidneys in adult rats

Objective Intrauterine growth restriction (IUGR) is associated with hypertension and chronic kidney disease in adulthood. Postnatal overnutrition after IUGR may be of pathogenic importance for the development of diabetes and cardiovascular disease. This study was to identify the effects of IUGR and a postnatal high-protein diet on the kidneys in adult rats. Methods Intrauterine growth restriction was induced in Sprague-Dawley rats by isocaloric protein restriction in pregnant dams. IUGR pups were divided into two groups that were a standard-protein diet (IUGR group) or a high-protein diet (HP group). A comparative proteomic method was used to study the differences of protein expression profiles between normal adult rats and adult rats with IUGR and the effects of a postnatal high-protein diet on the protein expression profiles of the kidneys. Results The IUGR adults had higher urinary excretion of protein and blood pressure than controls and the HP diet caused more severe hypertension and proteinuria than IUGR itself. The differential proteomic expression analysis found 12 proteins that had significantly differential expression between the IUGR and control groups, which were transcription regulators and structural molecules. The differential proteomic expression analysis between the HP and control groups found 13 proteins that had significantly differential expression and were involved primarily in body metabolism, oxidation reduction, and apoptosis regulation. Conclusion An HP diet intervention after IUGR worsens the severity of hypertension and proteinuria, and this study may provide valuable experimental evidence of proteins involved in the pathogenesis of kidney disease in IUGR and the effect of postnatal overnutrition.

High-protein/high red meat and high-carbohydrate weight-loss diets do not differ in their effect on faecal water genotoxicity tested by use of the WIL2-NS cell line and with other biomarkers of bowel health

The impact of popular weight-loss diets with different macronutrient profiles on bowel health in humans has not been previously assessed. The aim of this study was to investigate whether a high-protein/high red meat (HP) diet influences faecal water genotoxicity and other standard biomarkers of bowel health differently compared with a high-carbohydrate (HC) diet. Thirty-three male subjects were randomly assigned to a HP (35% protein, 40% carbohydrate) or HC (17% protein, 58% carbohydrate) isocaloric energy-restricted dietary intervention consisting of 12 weeks intensive weight loss followed by weight maintenance for up to 52 weeks. Faecal samples were collected at 0, 12 and 52 weeks. Faecal water genotoxicity was assessed in the WIL2-NS human B lymphoblastoid cell line by means of the cytokinesis-block micronucleus cytome assay. Average weight loss after 12 weeks was 9.3 ± 0.7 kg for both diets, with no further change in weight at 52 weeks. Two-way ANOVA showed a significant effect with time ( P < 0.001) but not diet for total DNA damage, with a reduction in genotoxicity after 12 weeks intensive weight loss, and a subsequent increase after 9 months weight maintenance to levels not significantly different from baseline. There was no significant effect for time or diet on faecal pH, short-chain fatty acid excretion, phenol or p-cresol. Results suggest that HP and HC weight-loss diets may modify the carcinogenic profile of the bowel contents such that weight loss may exert a beneficial effect by reducing genotoxic load in the short term; however, these results require verification against a non-weight-loss control.

Feeding a diet with a decreased protein content reduces both nitrogen content in the gastrointestinal tract and post-weaning diarrhoea, but does not affect apparent nitrogen digestibility in weaner pigs challenged with an enterotoxigenic strain of Escherichia coli

This study evaluated possible nutritional and physiological mechanisms to explain why feeding a diet of decreased protein content reduces PWD. A total of 48 male pigs weaned at 21 d (initial BW 6.9 ± 0.11 kg; mean ± SEM) was used in a 2 × 2 × 2 factorial arrangement of treatments with the respective factors being: (1) PL (HP 239 g/kg vs. LP 190 g/kg CP); (2) presence or absence of an ETEC challenge; and (3) duration of feeding after weaning until euthanasia (D; 7 d vs. 14 d). No dietary antimicrobial compounds were used, and diet LP contained crystalline AA including isoleucine and valine to achieve an ideal AA pattern. Pigs were offered the experimental diets on an ad libitum basis. Feeding a LP diet decreased total N intake, ileal N flow, PUN and NH 3-N contents at the ileum and all sites in the large intestine (P<0.05–0.001), but did not alter (P>0.05) the AID of N and AA at either d 7 or d 14, except for serine which was lower in pigs fed the LP diet (P<0.001). Feeding diet HP increased the incidence of PWD, and ETEC infection increased PWD only in pigs fed the HP diet (PL × ETEC interaction, P<0.05). Pigs fed diet HP had more PWD at d 7 but not at d 14 after weaning (PL × D interaction, P<0.05). Experimental ETEC infection increased (P<0.001) faecal Escherichia coli score compared to non-infected pigs, and decreased AID of some AA at d 7 (ETEC × D interaction, P<0.05–0.001). Feeding diet LP reduced the molar proportion of BCFA in the caecum and proximal colon (P<0.001 and P<0.05, respectively), but total VFA concentrations in this organ were unaffected by PL (P>0.05). Pigs fed diet LP had decreased pH in the jejunum and ileum (P<0.05 and P<0.01, respectively), while ETEC infection increased pH in the caecum and proximal colon at d 7 (ETEC × D interaction, P<0.05). Feeding diet LP did not alter GIT weight, but ETEC infection adversely affected the proportional weight of the GIT at d 7 (ETEC × D interaction, P<0.01). The PL did not alter small intestinal morphology and growth. These results suggest that feeding a LP diet immediately after weaning reduces the flow of N into the large intestine, thereby decreasing protein fermentation without altering apparent AA digestibility at the ileum.

Colon luminal content and epithelial cell morphology are markedly modified in rats fed with a high-protein diet

Hyperproteic diets are used in human nutrition to obtain body weight reduction. Although increased protein ingestion results in an increased transfer of proteins from the small to the large intestine, there is little information on the consequences of the use of such diets on the composition of large intestine content and on epithelial cell morphology and metabolism. Rats were fed for 15 days with either a normoproteic (NP, 14% protein) or a hyperproteic isocaloric diet (HP, 53% protein), and absorptive colonocytes were observed by electron microscopy or isolated for enzyme activity studies. The colonic luminal content was recovered for biochemical analysis. Absorbing colonocytes were characterized by a 1.7-fold reduction in the height of the brush-border membranes (P = 0.0001) after HP diet consumption when compared with NP. This coincided in the whole colon content of HP animals with a 1.8-fold higher mass content (P = 0.0020), a 2.2-fold higher water content (P = 0.0240), a 5.2-fold higher protease activity (P = 0.0104), a 5.5-fold higher ammonia content (P = 0.0008), and a more than twofold higher propionate, valerate, isobutyrate, and isovalerate content (P < 0.05). The basal oxygen consumption of colonocytes was similar in the NP and HP groups, but ammonia was found to provoke a dose-dependent decrease of oxygen consumption in the isolated absorbing colonocytes. The activity of glutamine synthetase (which condenses ammonia and glutamate) was found to be much higher in colonocytes than in small intestine enterocytes and was 1.6-fold higher (P = 0.0304) in colonocytes isolated from HP animals than NP. Glutaminase activity remained unchanged. Thus hyperproteic diet ingestion causes marked changes both in the luminal environment of colonocytes and in the characteristics of these cells, demonstrating that hyperproteic diet interferes with colonocyte metabolism and morphology. Possible causal relationships between energy metabolism, reduced height of colonocyte brush-border membranes, and reduced water absorption are discussed.

Dietary protein level and probiotic supplementation effects on piglet response to Escherichia coli K88 challenge: Performance and gut microbial population

Thirty-six piglets weaned on day 21 were used to investigate the effect of dietary crude protein (CP) and non-pathogenic Escherichia coli probiotic on performance of piglets subjected to E. coli K88 challenge in a 12-d study. A 2 × 3 factorial arrangement with two levels of CP (HP, 22% vs LP 17%) and three additives types (no additive, NA; in-feed antibiotic, AB; and probiotic, PRO) constituted the 6 treatments. The PRO diets were prepared each morning by mixing 50 ml of 9 × 10 10 cfu/ml of fresh probiotic cultures with fresh feed. After a 6-d adaptation period, pigs were orally inoculated with a 6 ml of E. coli K88 (2 × 10 10 cfu/ml). Pigs fed the LP diets had higher ADG during pre- and post-inoculation period than pigs fed the HP diets. The LP fed pigs plus PRO had superior ( P < 0.05) ADG post-inoculation compared to the AB treatment. Pigs fed with LP diets had lower ( P < 0.05) post-inoculation FC scores than pigs fed with HP diets. Ileal mucosal counts of E. coli K88 were lower ( P < 0.05) for the AB and PRO treatments 7 d post-challenge than other treatments. In conclusion, the 17% dietary CP level resulted in superior performance in piglets than 22% dietary CP level and the LP diet and E. coli-based probiotic acted synergistically resulting in better performance in post-weaning piglets.

Effects of Dietary Protein Level and Phase Feeding Regimen on Growth Performance, Carcass Characteristics and Pork Quality in Growing-finishing Pigs

Two experiments were conducted to study the effects of dietary protein level and phase feeding regimens on performance, carcass characteristics and pork quality in growing-finishing pigs. In both experiments, growing pigs (n=90; barrows; Landrace <TEX>$\times$</TEX> Yorkshire <TEX>$\times$</TEX> Duroc) were allotted to 3 treatments. Each treatment had 3 replicate pens comprising 10 pigs in each. In Exp. 1, pigs (average body weight <TEX>$25.06{\pm}0.57\;kg$</TEX>) were fed diets having low (17.50-14.50-12.51%), medium (19.49-17.50-13.87%) or high (22.47-19.49-16.36%) CP concentration (LP, MP and HP diets, respectively) diets during grower-finisher I-finisher II phases, respectively. Feeding of MP diet resulted in higher (P<0.05) ADG and better FCR than pigs fed LP diet. Pigs fed HP diet had lower (P<0.05) pork color and marbling score. Meat of pigs fed LP diet had higher (P<0.05) Thiobarbituric acid reactive substances (TBARS), while meat of pigs fed HP and LP diets had greater drip loss than pigs fed MP diet. In addition, meat from pigs fed LP diet was darker while meat of pigs fed HP and MP diets was paler and redder. In Exp. 2, pigs (average body weight <TEX>$10.40{\pm}0.61\;kg$</TEX>) were subjected during 126 days to three or four phase regimes of different duration. The treatments T1 and T2 were subjected to four phase feeding regimens (grower I, grower II, finisher I and finisher II) for 22, 42, 32 and 30 days (T1) and 40, 40, 25 and 21 days (T2), respectively, while T3 was subjected to three phase feeding regimen (grower I, grower II and finisherI) for 40, 56 and 30 days, respectively. Duration of phase feeding regimens had no effect (P>0.05) on the performance, carcass traits and meat quality of pigs. These results suggest that both high and low levels of CP have a negative effect on performance and pork quality; however, alterations in the phase feeding regimens do not have any discernible effect on the performance and pork quality in growing-finishing pigs.

Maternal preconceptional nutrition leads to variable fat deposition and gut dimensions of adult offspring mice (C57BL/6JBom)

Maternal nutrition during pregnancy or lactation may affect the chance of offspring becoming obese as adults, but little is known regarding the possible role of maternal nutrition before conception. In this study, we investigate how variable protein and carbohydrate content of the diet consumed before pregnancy affects fat deposition and gut dimensions of offspring mice. Eight-week-old female mice (C57BL/6JBom) were fed isocaloric low protein (8.4% protein; LP), standard protein (21.5% protein; ST) or high protein (44.2% protein; HP) diets. After 8 weeks of feeding, females were mated and fed a standard laboratory chow diet (22.5% protein) throughout periods of mating, gestation, lactation and weaning. Offspring mice were fed the same standard diet up to 46 days of age. Then offspring were killed and measures of dissected fat deposits and of the digestive system were taken. Fat deposition of the offspring was significantly affected by preconceptional maternal nutrition and the effects differed between sexes. Male offspring deposited most fat when mothers were fed the LP diet, whereas female offspring deposited most fat when mothers were fed the ST diet. The mass and length of the digestive organs were affected by preconceptional maternal nutrition. Total gut from pyloric sphincter to anus was significantly shorter and dry mass was heavier in mice whose mothers were fed LP diets compared with offspring of mothers fed ST diets or HP diets. There was no significant effect of maternal nutrition on dry mass of the stomach or ceca. Our study shows that preconceptional nutrition can have important influence on several body features of offspring in mice, including body composition and dimensions of the digestive system.

Influence of dietary protein on fecal quality and gene expression of apoptosis‐ and immune‐related genes in the colon of Miniature Poodles and German Shepherds

Digestive tolerance vary among dog breeds, which could be partially attributed to higher colonic fermentation. Highly digestible protein sources, such as wheat gluten, could lead to lower colonic protein fermentation. Our aim was to assess the effect of dietary protein on fecal quality, and mRNA expression of genes involved in colonocyte apoptosis and mucosa immune responses.Five Miniature Poodles (MP) and 6 German Shepherds (GS) were fed with diets varying in protein source and level: low‐protein wheat gluten meal (LP) and high‐protein poultry meal (HP). Feces were scored daily (1=dry; 5=liquid) and fecal moisture was analyzed. Colonic biopsies followed each 14‐d trial period. The mRNA expression of proteins involved in apoptosis (Bcl‐2, Casp3), and in mucosa immune responses (IL7, TLR2, TLR4) was analyzed by RT‐real time PCR.Fecal score and moisture were higher in GS than MP, and when feeding HP diet. The expression of IL7 was higher in GS than MP (P &lt; 0.05), and when dogs were fed with HP diet (P = 0.03). The TLR2 mRNA expression was higher in the proximal colon of GS than MP (P = 0.08), and when feeding HP diet to GS (P = 0.03).Up‐regulation of immune‐related proteins could indicate a higher response to commensal bacteria, leading to a lower quality of feces. Diets containing low levels of highly digestible proteins could be an adequate nutritional strategy to improve fecal quality. Research supported by Royal Canin.

Leucine Supplementation of a Low Protein Meal Increases Skeletal Muscle and Visceral Tissue Protein Synthesis in Neonatal Pigs by Stimulating mTOR‐Dependent Translation Initiation

Leucine appears to be the most effective single amino acid to trigger the activation of translation initiation factors that regulate protein synthesis in muscle. The effects of Leu in visceral tissues are not well understood. We hypothesized that enteral Leu supplementation of a low protein diet (LP) in neonatal pigs will acutely increase skeletal muscle and visceral tissue protein synthesis to a rate similar to that achieved by feeding a high protein diet (HP). Fasted 5‐d‐old piglets (n=21) were gavage fed at 0 and 60 min either: 1) LP diet, 2) low protein diet supplemented with Leu (LP+L) to equal HP diet, or 3) HP diet. Diets were isocaloric and lactose was equal. Fractional protein synthesis rates and translational control mechanisms were examined 90 min after feeding. Protein synthesis increased in longissimus dorsi, gastrocnemius, masseter, heart, jejunum, kidney and pancreas, but not liver, of the LP+L group compared to LP group alone and did not differ from HP group. LP+L and HP increased translational efficiency and phosphorylation of S6K1 and 4E‐BP1 in all tissues except liver. Our results suggest that low protein diets supplemented with leucine stimulates protein synthesis in muscle and most visceral tissues to a rate similar to that achieved by high protein diets and this stimulation involves activation of mTOR downstream effectors. (Supported by Ajinomoto Amino Acid Research Program and USDA 58‐6250‐6‐001).Grant Funding Source: Ajinomoto Amino Acid Research Program and USDA 58‐6250‐6‐001

Chronic Enteral Leucine Supplementation of a Low Protein Diet Increases Skeletal Muscle Protein Synthesis in Neonatal Pigs by Stimulating mTOR‐Dependent Translation Initiation

Leucine appears to be the key amino acid that positively regulates mTOR signalling. We hypothesized that prolonged feeding (24 hours) of a Leu supplemented low protein (LP) diet in neonatal pigs will increase protein synthesis in skeletal muscle to a rate similar to that of a high protein diet (HP). Fasted 5‐d‐old piglets (n=17) were gavage fed every 4 hours either: 1) LP diet, 2) low protein diet supplemented with Leu (LP+L) to equal HP diet, or 3) HP diet. Diets were isocaloric and lactose was equal. Fractional protein synthesis rates and translational control mechanisms were examined after 24 hours. Protein synthesis increased in the skeletal muscle of the LP+L group compared to LP group alone and did not differ from HP group. LP+L and HP increased the phosphorylation of S6K1 and 4E‐BP1, decreased inactive 4E‐BP1 eIF4E complex abundance, and increased active eIF4E eIF4G complex formation in skeletal muscle. Our results suggest that chronic feeding of a low protein diet supplemented with leucine stimulates and maintains the protein synthesis response in skeletal muscle to a rate similar to that achieved by feeding a high protein diet and this stimulation involves increased eIF4F complex assembly. (Supported by Ajinomoto Amino Acid Research Program and USDA 58‐6250‐6‐001).Grant Funding Source: Ajinomoto Amino Acid Research Program and USDA 58‐6250‐6‐001

Effects of exercise and high carbohydrate and high protein diets on women with and without metabolic syndrome (MS)

396 sedentary women (46±11 yrs, 163±7 cm; 92±18 kg; 45±4% fat) participated in the Curves® circuit training (3 d/wk) and weight loss program (1,200 kcal/d for 1‐wk; 1,600 kcal/d for 9‐wks that was 30% fat with 55% CHO in a HC group and 50–63% protein in a HP group) for 10‐wks. Subjects were divided into those with less than (n=218) or more than (n=178) 3 NCEP‐ATP III criteria for MS. Data were analyzed by MANOVA with repeated measures and are presented as means ± SD percent changes from baseline for the non‐MS and MS groups, respectively. Subjects with MS experienced significantly greater changes in fasting glucose (1.2±17; −3.0±15 %, p=0.016), TG (4.2±40; −8.7±30 %, p=0.001), SBP (−0.5±10; −4.3±12 %, p=0.001), and DBP (−1.2±12; −4.1±13 %, p=0.02). Although time effects were observerd, no differences were seen between groups in weight loss (−3.7±3.6; −4.0±3.6 %, p=0.40), fat loss (−6.5±6.7; −7.0±6.4 %, p=0.64), waist circumference (−3.1±6.0; −2.5±5.5 %, p=0.46), total CHL (−5.7±18; −5.3±19 %, p=0.75), or HDL (−3.8±20; −1.8±18 %, p=0.23). Subjects in the HP group tended to lose more weight (p=0.10) and had a greater reduction in TG (p=0.004). No time x MS x diet interactions were observed. Results revealed that exercise and diet promoted favorable changes in markers of MS; individuals with MS may experience greater benefits; and, a HP diet may promote greater reductions in TG levels.

Effects of protein intake on energy‐restriction‐induced changes in lipid‐lipoprotein profile, glycemic control, resting energy expenditure, and appetite in overweight men

PurposeTo assess the effects of dietary protein (pro) on diet‐induced changes in indices of metabolic health.MethodsFor 12 wk, overweight men (BMI 25.0–39.9 kg/m2), aged 24–75 y, consumed a 750 kcal/d energy deficit diet with 25% energy as fat, and either 15% pro (normal pro, NP, n = 21) and 60% CHO, or 25% pro (higher pro, HP, n = 22) and 50% CHO. The NP diet excluded striated tissue and eggs; the HP diet had 15% pro from eggs and 25% pro from lean pork. Pre and post‐study, fasting blood was taken; body composition, blood pressure (BP), and resting energy expenditure (REE) were measured; and daily appetite was assessed.ResultsReductions over time (p&lt;0.05) in the NP and HP groups included: weight 10 and 9%; fat mass 21 and 20%; lean body mass (LBM) 5 and 3%; cholesterol 18 and 22%; HDL 9 and 9%; LDL 19 and 20%; triacylglycerol 30 and 42%; insulin 3.7 ± 1.4 and 5.4 ± 1.2 μU/mL; HOMA 0.9 ± 0.2 and 1.4 ± 0.2; systolic:diastolic BP 8:6 and 7:8%; and REE 260 ± 112 and 97 ± 78 kcal/d. Diet did not influence these responses, except ΔLBM was greater in NP vs. HP (time × group, p&lt;0.05). ΔREE was predicted by ΔLBM (R2 = 0.21). Daily desire to eat ratings decreased in both groups, but hunger decreased in HP only.ConclusionOverweight men can successfully improve indices of metabolic health after weight loss when consuming a normal protein vegetarian or higher protein omnivorous diet.Support: Natl Pork Brd; Am Egg Brd‐Egg Nutr Ctr; Purdue Ingest Behav Res Ctr.Grant Funding Source: American Egg Board, National Pork Board

A High-Protein Diet With Resistance Exercise Training Improves Weight Loss and Body Composition in Overweight and Obese Patients With Type 2 Diabetes

OBJECTIVETo evaluate the effects of two low-fat hypocaloric diets differing in the carbohydrate-to-protein ratio, with and without resistance exercise training (RT), on weight loss, body composition, and cardiovascular disease (CVD) risk outcomes in overweight/obese patients with type 2 diabetes.RESEARCH DESIGN AND METHODSA total of 83 men and women with type 2 diabetes (aged 56.1 ± 7.5 years, BMI 35.4 ± 4.6 kg/m2) were randomly assigned to an isocaloric, energy-restricted diet (female subjects 6 MJ/day, male subjects 7 MJ/day) of either standard carbohydrate (CON; carbohydrate:protein:fat 53:19:26) or high protein (HP; 43:33:22), with or without supervised RT (3 days/week) for 16 weeks. Body weight and composition, waist circumference (WC), and cardiometabolic risk markers were assessed.RESULTSFifty-nine participants completed the study. There was a significant group effect (P ≤ 0.04) for body weight, fat mass, and WC with the greatest reductions occuring in HP+RT (weight [CON: −8.6 ± 4.6 kg, HP: −9.0 ± 4.8 kg, CON+RT: −10.5 ± 5.1 kg, HP+RT: −13.8 ± 6.0 kg], fat mass [CON: −6.4 ± 3.4 kg, HP: −6.7 ± 4.0 kg, CON+RT: −7.9 ± 3.7 kg, HP+RT: −11.1 ± 3.7 kg], and WC [CON: −8.2 ± 4.6 cm, HP: −8.9 ± 3.9 cm, CON+RT: −11.3 ± 4.6 cm, HP+RT: −13.7 ± 4.6 cm]). There was an overall reduction (P < 0.001) in fat-free mass (−2.0 ± 2.3 kg), blood pressure (−15/8 ± 10/6 mmHg), glucose (−2.1 ± 2.2 mmol/l), insulin (−4.7 ± 5.4 mU/l), A1C (−1.25 ± 0.94%), triglycerides (−0.47 ± 0.81 mmol/l), total cholesterol (−0.67 ± 0.69 mmol/l), and LDL cholesterol (−0.37 ± 0.53 mmol/l), with no difference between groups (P ≥ 0.17).CONCLUSIONSAn energy-restricted HP diet combined with RT achieved greater weight loss and more favorable changes in body composition. All treatments had similar improvements in glycemic control and CVD risk markers.

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.

The effect of the protein level in a pre-starter diet on the post-hatch performance and activation of ribosomal protein S6 kinase in muscle of neonatal broilers

The cytoplasmic serine/threonine ribosomal protein S6 kinase (S6K1) plays a critical role in controlling protein translation. There is evidence that amino acids regulate S6K1 and protein synthesis in avian species, but the effect of dietary protein level on the activation of S6K1 in neonatal chicks is unknown. Therefore, the aim of the present experiment was to investigate the effect of different protein levels, supplied during the first 5 d post-hatch, on body growth, breast muscle development and on the activation of S6K1 and its downstream target, the S6, in neonatal chicks. Chicks were fed a pre-starter diet during the first 5 d post-hatch containing low (19.6 % crude protein (CP); LP), medium (23.1 % CP; MP) or high (26.7 % CP) levels (HP) of protein. Weight gain of chicks fed the HP diet was higher (P < 0.05) compared with those fed the LP diet during day (d)3-d5 and the numerical advantage of this group was maintained from d2 to d7. On d2 and d3, greater levels of S6K1 and S6 phosphorylation and/or activity were observed in chicks receiving the HP diet compared with LP and MP diets, without differences between results of the latter two dietary treatments. In conclusion, the present results suggest that early protein nutrition impacts the development of broiler chicks.

Can choice feeding improve performances and N-retention of broilers compared to a standard three-phase feeding schedule?

1. An experiment was conducted to investigate if broilers can improve their performances and N-retention using choice feeding (CF). 2. Treatment 1 consisted of a standard three-phase feeding regime (SF). Treatments 2–7 were CF treatments with a high (HP) and a low protein (LP) feed offered simultaneously to the birds. Choice feeding started at day 1 or 8 and feeds were offered in mash form or as pellets. 3. When choice feeding was started at day 1 and the HP diet was mash, growth rates were increased (+4·2%) compared to SF, whereas all other CF treatments showed similar or significantly lower final body weights compared to SF. Feed conversion was increased for all CF strategies. 4. Highest yield and breast meat percentages were obtained if the low protein diet was pelleted. The amount of N excreted was increased for most choice feeding treatments as a result of the increased N-intakes and the less efficient growth. 5. Broilers were able to make a choice between two feeds differing in protein/amino acid contents starting as early as day 1, but choices were influenced by feed form. The results confirmed that very high protein/amino acid concentrations in the starter period are desirable to improve growth rates in fast-growing chickens.

Performance, carcass characteristics and chemical composition of beef affected by lupine seed, rapeseed meal and soybean meal

To test the effects of different protein sources and levels on performance, carcass characteristics and beef chemical composition, concentrates with three protein sources [Lupine seed (L), Rapeseed meal (R) and Soybean meal (S)] and two protein levels ['normal protein' (NP) or 'high protein' (HP)] were fed to 36 Simmental calves. Calves initially weighed 276 +/- 3.9 kg and averaged 6 months of age and were randomly allocated to the six treatments. Maize silage was offered ad libitum and supplemented with increasing amounts of concentrates (wheat, maize grain, protein sources, vitamin-mineral mix). Normal protein and HP diets were formulated to contain 12.4% and 14.0% crude protein (CP) dry matter (DM) respectively. At the end of the fattening period of 278 days, the final live weight averaged 683 +/- 14.7 kg. Neither level of protein nor its interaction with protein sources had any effects on most of the traits studied. Feeding the R diet significantly increased final weight, average daily gain (ADG), DM intake and CP intake in relation to the L diet; no differences were observed between the L and S diets for these measures. No differences were observed between the R and S groups in final weight or ADG, but the calves fed the R diet consumed more DM and CP than the calves fed the S diet. Bulls fed R diet had higher carcass weight and dressing percentage than the L groups, and no significant differences were detected between the S and L groups. Chemical composition of the Musculus longissimus dorsi was not significantly affected by source of protein. Also, the major saturated fatty acid (SFA) (C16:0 and C18:0) did not significantly differ among the three treatments. Samples from R group had significantly higher proportions of C16:1 t9, C18:1 c11, C18:2 c9 t11, C18:3 c9, 12, 15 and SigmaC18:1 t fatty acids in relation to L and S groups. Although polyunsaturated fatty acid/SFA ratio was similar for the three dietary groups, n-6/n-3 ratio and Sigman-3 fatty acids content were significantly greater for bulls fed R diet in relation to those fed L and S diets.

Effect of feed composition and temperature on food consumption, growth and gastric evacuation of juvenile Atlantic cod ( Gadus morhua L.) and haddock ( Melanogrammus aeglefinus L.)

During sea-cage rearing, Atlantic cod and haddock are fed commercial diets that have high protein content (∼ 50–58%) and are designed for optimum growth at temperatures of 10–12 °C. However, these fish spend several months at temperatures below 5 °C in Atlantic Canada, and there are data to suggest that growth could be enhanced at low water temperatures by feeding a diet with lower protein (LP) content and higher lipid. Thus, we explored how dietary protein and lipid (P/L) levels of 42/16 (low protein, LP diet) and 55/11 (high protein, HP diet) and water temperature (11, 6 and 2 °C) influenced the specific growth rate (SGR), hepatosomatic index (HSI), adjusted specific growth rate (SRG A), food consumption (FC), gross conversion efficiency (GCE) and gastric evacuation (GE) of juvenile Atlantic cod and haddock. Several temperature and species-specific effects were observed for the measured variables. Significant decreases in SGR, SGR A and FC (range 60–96%) were evident for both species when reared at 2 vs. 11 °C. The GCE of haddock was 46 and 31% (for HP and LP diets, respectively) higher than that measured for Atlantic cod at 11 °C, but 35 and 40% lower at 2 °C. With regards to the effects of dietary protein level, it was found that while feed composition did not affect growth rate (with the exception of haddock at 11 °C) or GE, GCE was significantly lower in fish fed the LP diet. These results indicate that 1) low temperatures present a particular challenge to haddock aquaculture; and 2) based on the similar growth rate, but lower GCE values, there is no advantage to feeding an LP diet even at cold temperatures.

Protein Intake during Weight Loss Influences the Energy Required for Weight Loss and Maintenance in Cats1–3

The effects of 2 diets with different protein contents on weight loss and subsequent maintenance was assessed in obese cats. The control group [Co; n = 8; body condition score (BCS) = 8.6 ± 0.2] received a diet containing 21.4 g crude protein (CP)/MJ of metabolizable energy and the high-protein group (HP; n = 7; BCS = 8.6 ± 0.2) received a diet containing 28.4 g CP/MJ until the cats achieved a 20% controlled weight loss (0.92 ± 0.2%/wk). After the weight loss, the cats were all fed a diet containing 28.0 g CP/MJ at an amount sufficient to maintain a constant body weight (MAIN) for 120 d. During weight loss, there was a reduction of lean mass in Co (P < 0.01) but not in HP cats and a reduction in leptinemia in both groups (P < 0.01). Energy intake per kilogram of metabolic weight (kg−0.40) to maintain the same rate of weight loss was lower (P < 0.04) in the Co (344 ± 15.9 kJ·kg−0.40·d−1) than in the HP group (377 ± 12.4 kJ·kg−0.40·d−1). During the first 40 d of MAIN, the energy requirement for weight maintenance was 398.7 ± 9.7 kJ·kg−0.40·d−1 for both groups, corresponding to 73% of the NRC recommendation. The required energy gradually increased in both groups (P < 0.05) but at a faster rate in HP; therefore, the energy consumption during the last 40 d of the MAIN was higher (P < 0.001) for the HP cats (533.8 ± 7.4 kJ·kg−0.40·d−1) than for the control cats (462.3 ± 9.6 kJ·kg−0.40·d−1). These findings suggest that HP diets allow a higher energy intake to weight loss in cats, reducing the intensity of energy restriction. Protein intake also seemed to have long-term effects so that weight maintenance required more energy after weight loss.