Dietary Protein Content Research Articles

103 The Role of Crude Protein in Reducing the Need for Antibiotics in the Post-weaning Period

Abstract For many decades, antimicrobial compounds such as antibiotics and some mineral compounds have been used in pork production to promote pig growth and survival after weaning through mitigation of subclinical and clinical diseases, such as enterotoxigenic strains of Escherichia coli. Bans and restrictions in the use of some antimicrobial compounds has led, often out of necessity, to the development of alternative feeding strategies to address these challenges. One tool to reduce the post-weaning malaise in the absence of specific antimicrobial compounds is manipulation of the protein content of diets offered to pigs. Numerous studies have shown that feeding higher crude protein diets in the post-weaning period, usually in the absence of specific antimicrobials, is generally related to decreased fecal consistency (looser stools) and an increased incidence of post-weaning diarrhea. In some cases, this causes more therapeutic antibiotic administrations, more animal care, and a greater mortality. Production indices are poorer as a consequence. Conversely, feeding diets of lower crude protein content after weaning has typically been associated with better health outcomes, but if diets are not correctly formulated with the addition of appropriate crystalline amino acids, then production outcomes can suffer. Increasing the quantity of fermentable protein entering the cecum and colon by feeding more dietary protein will stimulate changes in microbial composition, with the microbiota shifting to a more N-utilizing community resulting in greater protein catabolic activity and the increased production of products including ammonia, amines and branched-chain fatty acids. This, in turn, can be associated with increased diarrhea. Formulating starter diets that limit the flow of exogenous and endogenous proteinaceous compounds posteriorly to the ileo-caecal valve can be used to reduce the post-weaning malaise and may minimize the use of certain antimicrobial compounds. However, feeding lower-protein diets alone is not always the panacea to this production issue, and will likely need to be used in conjunction with other targeted nutritional and health measures specific to the farm in question.

Evaluation of protein: lipid ratio on growth, feed efficiency, and metabolic response in juvenile yellowtail snapper Ocyurus chrysurus (Bloch, 1791)

This study was conducted to evaluate juveniles' Ocyurus chrysurus (13.7 ± 0.45 g initial weight) to utilize lipid as an energy source on growth, feed efficiency, body composition, digestive and hepatic enzyme activities. Four diets of two protein levels (40 and 50%) with two lipid levels (6 and 12%) and 2% of digestible carbohydrates were formulated. Fish were fed for 60 days to apparent satiation at a stocking density of 10 fish per tank (100 L). Growth gain of fish fed 50% dietary protein was higher than of fish fed 40% dietary protein (P < 0.05). However, feed efficiency was significantly higher at 12 than 6% of dietary lipid. Whole-body lipid and glycogen in the liver increased dramatically with dietary lipid content-alkaline protease activity trend increased as dietary protein increased. Trypsin activity increased significantly as dietary lipid decreased, whereas chymotrypsin activity showed the opposite trend (P < 0.05). Bile salt-dependent lipase activity trend towards increasing as dietary energy decreased. Glucose-6-phosphate dehydrogenase (G6PDH), 6-phosphogluconate dehydrogenase (6PGDH), and fructose-1, 6-biphosphatase (FBPase) significantly increased with increasing dietary lipid levels. However, alanine aminotransferase (ALT) activity increased with dietary protein content. On the other side, pyruvate kinase (PK) activity increased with both dietary protein and lipid content. This study indicates that high dietary lipid (12%) improved the feed efficiency but did not reduce dietary protein demand in juveniles O. chrysurus.

Diet Protein Content and Individual Phenotype Affect Food Intake and Protein Appetence in Rats

BackgroundA low-protein diet can induce compensatory intake of excess energy. This must be better evaluated to anticipate the obesogenic risk that may result from the dietary recommendations for reducing animal protein consumption. ObjectivesWe aimed to further characterize the behavioral and physiological responses to a reduction in dietary protein and to identify the determinants of protein appetite. MethodsThirty-two male Wistar rats [4 wk old, (mean ± SEM) 135 ± 32 g body weight] were fed a low-protein (LP; 6% energy value) or normal-protein (NP; 20%) diet for 8 wk. Food intake and body mass were measured during the entire intervention. During self-selection sessions after 4 wk of experimental diets, we evaluated rat food preference between LP, NP, or high-protein (HP; 55%) pellets. At the end of the experiment, we assessed their hedonic response [ultrasonic vocalizations (USVs)] and c-Fos neuronal activation in the olfactory tubercle and nucleus accumbens (NAcc) associated with an LP or HP meal. ResultsRats fed an LP diet had greater food intake (24%), body weight (5%), and visceral adiposity (30%) than NP rats. All LP rats and half of the NP rats showed a nearly exclusive preference for HP pellets during self-selection sessions, whereas the other half of the NP rats showed no preference. This suggests that the appetite for proteins is driven not only by a low protein status but also by individual traits in NP rats. LP or HP meal induced similar USV emission and similar neuronal activation in the NAcc in feed-deprived LP and NP rats, showing no specific response linked to protein appetite. ConclusionsProtein appetite in rats is driven by low protein status or individual preferences in rats receiving adequate protein amounts. This must be considered and further analyzed, in the context of current recommendations for protein intake reduction.

Quercetin from Sophora japonica alleviates growth retardation of broilers on a low protein diet

Abstract The aim of this experiment was to study the effects of low dietary crude protein (CP) content and supplementation with quercetin on growth performance and further production parameters of broiler chicks. A total of 360 1-day-old broiler chicks were randomly assigned to one of 4 dietary treatments for a 35-day trial (starter, days 1–7; grower, days 8–21; finisher, days 22–35). There were 5 replicate cages and 18 birds per cage in each dietary treatment. Dietary treatments included standard CP content (SCP) diet, low CP content (LCP) diet, and LCP diet supplemented with 0.025 or 0.050% quercetin. The CP content of the diet was the same in the LCP group as in the SCP group on days 1–7, while it was lower than in the SCP group on days 8–21 (20.96 vs. 21.50% CP) and 22–35 (19.50 vs. 20.00% CP). Broiler chicks given the LCP diet had lower body weight gain (BWG) during days 8–21 and 1–35 and higher relative weight of abdominal fat than those given the SCP diet. Moreover, the addition of quercetin to the LCP diet resulted in a positive linear response in BWG during days 8–21 and 1–35 and a negative linear response in relative abdominal fat weight with the increase in quercetin dose. However, the nutrient digestibility, caecal microbiota, and excreta gas emission did not differ among the dietary groups. Therefore, supplementing quercetin ameliorated the growth deterioration and abdominal fat enhancement caused by reducing dietary CP content.

Nutritional and mineral composition of persimmon fruits (Diospyros kaki L.) from Central and Southern Italy

In this study, the nutritional and mineral composition of Diospyros kaki fruits from Apulia, Campania, Lazio, Sardinia and Sicily regions was evaluated. Dietary fiber, mineral, pectin, polyphenol, and protein contents were evaluated. Particularly high are the contents of the dietary fiber and pectins. The mineral elements profile was interesting due to its modest content of sodium and high potassium concentration. Protein amounts were in line with the quantities for this fruit. The total polyphenol content of the fruits analysed was very variable, interesting for the quantities found both total and gallic acid. The results obtained confirmed the nutritional value of this fruit even for special dietary regimens such as hypertension and heart diseases and the genuineness of its cultivation in Central-Southern Italy.

Clinical Findings in Healthy Dogs Fed With Diets Characterized by Different Carbohydrates Sources.

In recent years, pet owners have become more interested in the ingredients, and quality of pet-food, and several studies have demonstrated that feed management could affect healthy status. Recently, some authors indicated that commercial diets formulated without cereals, or using unconventional protein, and starch sources, can cause a reduction in taurine levels in both whole blood, and plasma. Nevertheless, the specific mechanism by means of which nutritional factors determine this reduction is not completely clear. Thirty neutered half-breed dogs were recruited at a kennel in the province of Naples (Italy) to investigate the influence of carbohydrates sources, and dietary density of nutrients on healthy status of dogs in terms of blood count, and biochemical parameters. The dogs were housed in the kennel and divided into three distinct groups. Three iso-energy, and iso-nitrogen commercial kibble diets (named GF1, GF2, and CB) with different protein, and carbohydrates contents, and carbohydrates sources were chosen for the trial. The chemical composition and amino acid profile of each of the three tested diets were analyzed. Moreover, blood samples of each dog were collected to evaluate the hematological and biochemical profiles. The taurine level was determined both on plasma and whole blood. The effect of the diets was analyzed statistically, and all tested diets were compared to the control one. There were significant differences between the three tested diets as regards their chemical composition. The concentrations of all amino acids seem to reflect protein content diets. The hematological profile resulted within the ranges considered physiological for the canine species for all subjects. Compared to the control diet, the three tested diets showed significant differences in blood count for MCHC and platelets. The biochemical profile showed significant differences between the diets, particularly their AST, fructosamine, lipase, and triglycerides values. The diets did not affect the blood and plasma taurine levels. They resulted in higher than optimal reserve levels. Preliminary results showed that the sources of carbohydrates and use of balanced diets affected only some biochemical parameters and did not alter the levels of taurine in healthy adult dogs.

Effect of various commercial diets on rearing performance, body chemical and fatty acid composition, liver histology and vertebral column anomalies in Eurasian perch (Perca fluviatilis L.) post-larvae

The effects of three commercial diets (AF PE and PP) that differed in nutritional value on growth, cannibalism and survival in Eurasian perch post-larvae were performed. Of the feeds used, the PE feed contained a lower level of crude protein and a higher level of crude fat with a higher level of saturated fatty acids (SFA) and a lower level of polyunsaturated fatty acids (PUFA) than the AF and PP feeds. Additionally, chemical composition, including the fatty acid (FAs) content of perch body, liver histology and vertebral column anomalies relative to tested diets were analysed. It was shown that the two-month perch fed by diet with the highest fat content and the lowest protein content (PE) achieved significantly higher weight and body length. During the experiment, a relatively higher survival was obtained in perch groups fed with PE and PP feeds. Significantly lower type II intra-cohort cannibalism in perch fed with two diets (PE and PP) was observed, which probably resulted from better assimilation and, consequently, a sense of greater satiety in fish (PE diet) and faster perception by perch of its presence in the experimental system (PP diet). Moreover, the increase in type II cannibalism in perch fed with the AF diet could be due to the poorer palatability of this feed (understood in terms of its availability). The results of our study confirmed the hypothesis that the level of fat in the body of fish depended on the level of crude fat from feed used; however, it was also found that the fatty acid composition of the perch body was irrespective of the content of FAs in the diet used. Our data suggest that differences in the level of proximate and FAs compositions in tested commercial diets do not affect the histological structure of the liver and the prevalence of skeletal malformation in Eurasian perch post-larvae.

Effects of Dietary Protein Level on the Gut Microbiome and Nutrient Metabolism in Tilapia (Oreochromis niloticus).

Simple SummaryDietary protein is an important factor affecting aquaculture. In this study, the homeostasis of the gut microbiome and metabolic profile of the liver and serum of tilapia were analyzed, comparing those fed with different diets to evaluate the effect of diet on protein levels. As a result, there was no significant difference found in the diversity and richness of the gut microbiome but had differences in the microbial composition of the gut among different groups. As for the liver metabolome of the tilapia, the glucose content increased along with increased protein levels. As for serum metabolome, the levels of tyrosine, guanosine, and inosine were significantly different. In summary, diets with different protein levels can affect the composition of gut microbiota and glycolysis and amino acid metabolism in tilapia. These results may also help to improve the conditions of tilapia cultivation.Dietary protein is one of the most important nutritional factors in aquaculture. The aim of this study was to examine the effects of dietary protein levels on the gut microbiome and the liver and serum levels of metabolites in tilapia. Tilapia were fed a diet with a low (20%), moderate (30%), or high (40%) content of crude protein, and the homeostasis of the gut microbiome and metabolic profile of the liver and serum were analyzed. The results showed no significant differences in the diversity and richness of the gut microbiome among the groups; however, there were differences in the microbial composition of the gut. The metabolome analysis of liver samples revealed a difference in the glucose level among the groups, with the highest glucose level in fish fed a high protein diet. In addition, there were significant differences in the levels of tyrosine, guanosine, and inosine among the metabolome analysis of serum samples of these groups. In summary, diets with different protein levels could affect the composition of gut microbiota and the dynamic balance of microbial communities. Dietary protein content can also affect glycolysis and amino acid metabolism in tilapia.

Sensorial attributes and growth performance of whiteleg shrimp (Litopenaeus vannamei) cultured in biofloc technology with varying water salinity and dietary protein content

A study was conducted to evaluate the sensorial attributes and zootechnical performance of whiteleg shrimp (Litopenaeus vannamei) juveniles cultured in biofloc technology (BFT) with varying water salinities and proteinous feed. The experiment was conducted at two salinity levels viz., 5 ppt and 30 ppt each with two different proteinous feeds viz., 25% and 35% crude protein (CP), in a completely randomized factorial experimental design. Shrimp juveniles (average weight: 1.07 g) were stocked uniformly at the density of 233 shrimp m−3 in sixteen 60-L experimental tanks and reared for nine weeks. At the end of culture, all shrimps were harvested from the tanks and zootechnical parameters were recorded. The sensorial attributes viz., aroma, color, flavor, texture, and overall acceptance of shrimps reared in BFT under the tested treatments and in traditional earthen pond culture system were compared. In terms of zootechnical parameters, survival was similar among all treatments. The shrimp growth and productivity were significantly affected by either salinity and protein levels of feed. The same trend was observed for the feed conversion ratio and protein efficiency ratio. The highest shrimp growth (final weight: 4.08 g) was achieved in 30 ppt water with 35% CP. The sensorial attributes of shrimp were similar in all experimental treatments including those reared in traditional earthen pond. The results suggested that 30 ppt of water salinity and 35% of dietary crude protein promoted superior shrimp performance as compared to 5 ppt and 25% CP. Additionally, the current study revealed that sensorial attributes of L. vannamei cultured in BFT did not change regardless of the salinity (5 ppt and 30 ppt) and/or the dietary crude protein (25% and 35% CP), and was comparable to those reared in traditional earthen ponds.

Meat production of young and adult Kejobong goats fed diets with different protein concentration

This study was aimed to examine the effect of dietary crude protein (CP) concentration on carcass and meat production in young and adult Kejobong goats. This study used 8 young (5 months) and 8 adult (9 months) Kejobong goats; which were allocated to a randomized nested design, with an age of goat as the nest, and treatment applied was dietary protein concentration (T1: 9.96%; T2: 14.66%). The parameters observed were dry matter intake (DMI), CP intake (CPI), body weight gain (BWG), and the production of carcass meat. The results showed that the DMI of adult goats (910 g/d) was higher (P<0.05) than that of young goats (680 g/d). The goats fed diet T2 had higher (P<0.05) DMI, CPI, and BWG (855 g, 140 g, and 94 g/d, respectively) than those of T1 (725 g/d, 80 g/d, and 59 g/d). Slaughter weight, carcass weight and carcass meat weight, and carcass meat percentage of adult goats (28.09 kg, 13.19 kg, 8.60 kg and 64.94%, respectively) were higher (P <0.05) than those of young goats (20.06 kg, 8.72 kg, 5.46 kg, and 62.06%, respectively). The weight and percentage of carcass meat of T2 (8.30 kg and 64.99%, respectively) were higher (P<0.05) than those of T1 (5.75 kg and 62.06%, respectively). The meat-bone ratio of adult goats was higher (P<0.05) than that of young goats (3.53 vs 2.85). The meat-bone ratio of T2 (3.58) was higher (P<0.05) than that of T1 (2.80). It was concluded that adult Kejobong goats produced more meat than the young ones, and the goat-fed diet with 14.66% CP produced more meat than that with 9.96% CP.

167 Reducing the dietary protein content in dairy cow diets based on lucerne and maize silage does not affect performance but improves nitrogen use efficiency

167 Reducing the dietary protein content in dairy cow diets based on lucerne and maize silage does not affect performance but improves nitrogen use efficiency

Seasonal patterns of bison diet across climate gradients in North America

North American plains bison (Bison bison) have been reintroduced across their former range, yet we know too little about their current diet to understand what drove their past migrations as well as observed continental-scale variation in weight gain and reproduction. In order to better understand the seasonal diets of bison at the continental scale, bison fecal material was collected monthly from April to September in 2019 across 45 sites throughout the conterminous United States. Fecal material was analyzed for dietary quality using near infrared spectroscopy and dietary composition with DNA metabarcoding. As observed in previous research, dietary quality peaked in June and was on average greatest for sites with cold, wet climates. Yet, in April, dietary quality was highest in warmer regions, likely reflecting earlier phenology of plants in southern than northern regions. Independent of climate and season, bison that consumed more warm-season grasses had lower dietary protein concentrations. Interpreting the relative abundance of sequences from different plant species as the relative intake of protein from those species, only 38% of bison protein intake came from grasses. An equal amount of dietary protein came from legumes (38%) and 22% from non-leguminous forbs. Seasonal shifts in bison diet were also clear, in part, following the phenology of functional groups. For example, cool-season grass protein intake was highest in May, while legume protein intake was highest in August. Comparing data taken in June and September 2018 in a previous study with corresponding data in 2019, on average, June [CP] was 20% higher in 2019 than 2018, while September [CP] did not differ between years. Dietary functional group composition was generally similar in amounts and relationships with climate between years, yet in September 2019, legumes contributed 20% more protein and warm-season grasses 14% less than in September 2018. In all, this research demonstrates that bison consistently rely on eudicots for protein with the functional group composition of their diet in some ways consistent across space and time, but also spatially and temporally variable. The early-season inversion of plant quality gradients would have been a strong driver of migratory behavior for large numbers of bison optimizing protein intake. As most bison currently experience protein deficiency, optimizing protein intake under current non-migratory conditions will require increasing the relative abundance of high-protein species such as N2-fixing species.

Dining from the coast to the summit: Salmon and pine nuts determine the summer body condition of female brown bears on the Shiretoko Peninsula.

Body condition in mammals fluctuates depending on energy intake and expenditure. For brown bears (Ursus arctos), high‐protein foods facilitate efficient mass gain, while lipids and carbohydrates play important roles in adjusting dietary protein content to optimal levels to maximize energy intake. On the Shiretoko Peninsula, Hokkaido, Japan, brown bears have seasonal access to high‐lipid pine nuts and high‐protein salmon. To assess seasonal and annual fluctuation in the body condition of adult female brown bears in relation to diet and reproductive status, we conducted a longitudinal study in a special wildlife protection area on the Shiretoko Peninsula during 2012–2018. First, analyses of 2,079 bear scats revealed that pine nuts accounted for 39.8% of energy intake in August and salmon accounted for 46.1% in September and that their consumption by bears varied annually. Second, we calculated the ratio of torso height to torso length as an index of body condition from 1,226 photographs of 12 adult females. Results indicated that body condition continued to decline until late August and started to increase in September when salmon consumption increased. In addition, body condition began to recover earlier in years when consumption of both pine nuts and salmon was high. Furthermore, females with offspring had poorer body condition than solitary females, in particular in late August in years with low salmon consumption. Our findings suggest that coastal and subalpine foods, which are unique to the Shiretoko Peninsula, determine the summer body condition of female brown bears, as well as their survival and reproductive success.

DIETS AND DIETARY INGREDIENTS SELECTION BY BROILER CHICKEN: EFFECTS ON GROWTH PERFORMANCE, CARCASS QUALITY AND ECONOMICS OF PRODUCTION

A total of 90day – old Hypeco broiler chicks were used in a choice-feeding trial to investigate whether meat-type chicken could select adequate nutrients that would support fast growth rate from a choice of imbalanced diet and feed ingredients. Three diets were used: a control diet (diet A= 200g/kg CP, 3031 kcal/kg ME) and two test diets; a low protein, high-energy diet (diet B=166g/kgCP, 3021 kcal/kg ME) and a low-protein, low-energy diet (diet C=168g/kgCP, 2838 kcal/kg ME). The diets were fed singly. The test diets were also used in a choice-feeding with ground maize and soya-bean meal (SBM). The study lasted for 5weeks and the response criteria included growth performance, carcass and organ characteristics, and economics of production. Weight gain and feed conversion ratio were significantly (P < 0.01) and (P < 0.001 respectively) influenced. Birds on the control diets had the highest weight gain and best feed conversion ratio. Birds on the low-protein, high-energy diet had performances not significantly (P > 0.05) lower than the control. The low-protein, low-energy diet depressed performance. Feeding the imbalanced diets (diets B and C) singly produced better performances than feeding them with a choice of dietary ingredients. Birds exhibited selection potentials by selecting the ground maize and SBM to compensate for deficiencies in the imbalanced diets but not at a level adequate enough to improve performances. Only the relative chest weight was significantly (P < 0.05) influenced amongst the carcass and organ weights measured. It decreased with decreasing feed quality. Economics of production showed that low quality and cheaper priced feeds do not necessarily give higher income and profit. The benefits of feeding single balanced diets and the possibility of decreasing the protein content of broiler finisher diets without compromising profits were revealed. It was suggested that broiler chicken appeared to select nutrients for maximize economic performance and that feed quality control should be enforced.

Concurrent and carryover effects of feeding blends of protein and amino acids in high-protein diets with different concentrations of forage fiber to fresh cows. 1. Production and blood metabolites

Because of low feed intake during the first weeks of lactation, dietary concentration of metabolizable protein (MP) must be elevated. We evaluated effects of providing additional rumen-undegradable protein (RUP) from a single source or a blend of protein and AA sources during the first 3 wk of lactation. We also evaluated whether replacing forage fiber (fNDF) or nonforage fiber with the blend affected responses. In a randomized block design, at approximately 2 wk prepartum, 40 primigravid (664 ± 44 kg of body weight) and 40 multigravid (797 ± 81 kg of body weight) Holsteins were blocked by calving date and fed a common diet (11.5% crude protein, CP). After calving to 25 d in milk (DIM), cows were fed 1 of 4 diets formulated to be (1) 20% deficient in metabolizable protein (MP) based on predicted milk production (17% CP, 24% fNDF), (2) adequate in MP using primarily RUP from soy to increase MP concentration (AMP; 20% CP, 24% fNDF), (3) adequate in MP using a blend of RUP and rumen-protected AA sources to increase MP concentration (Blend; 20% CP, 24% fNDF), or (4) similar to Blend but substituting fNDF with added RUP rather than nonforage neutral detergent fiber (Blend-fNDF; 20% CP, 19% fNDF). The blend was formulated to have a RUP supply with an AA profile similar to that of casein. A common diet (17% CP) was fed from 26 to 92 DIM, and milk production and composition were measured from 26 to 92 DIM, but individual dry matter intake (DMI) was measured only until 50 DIM. During the treatment period for both parities, AMP and Blend increased energy-corrected milk (ECM) yields compared with the diet deficient in MP based on predicted milk production (40.7 vs. 37.8 kg/d) and reduced concentrations of plasma 3-methyl-His (4.1 vs. 5.3 µmol/L) and growth hormone (9.0 vs. 11.9 ng/mL). Blend had greater DMI than AMP (17.4 vs. 16.1 kg/d), but ECM yields were similar. Blend had greater plasma Met (42.0 vs. 26.4 µmol/L) and altered metabolites associated with antioxidant production and methyl donation compared with AMP. Conversely, the concentration of total essential AA in plasma was less in Blend versus AMP (837 vs. 935 µmol/L). In multiparous cows, Blend-fNDF decreased DMI and ECM yield compared with Blend (19.2 vs. 20.1 kg/d of DMI, 45.3 vs. 51.1 kg/d of ECM), whereas primiparous cows showed the opposite response (15.3 vs. 14.6 kg/d of DMI, 32.9 vs. 31.4 kg/d of ECM). Greater DMI for multiparous cows fed Blend carried over from 26 to 50 DIM and was greater compared with AMP (23.1 vs. 21.2 kg /d) and Blend-fNDF (21.3 kg/d). Blend also increased ECM yield compared with AMP (49.2 vs. 43.5 kg/d) and Blend-fNDF (45.4 kg/d) from 26 to 92 DIM. Few carryover effects of fresh cow treatments on production were found in primiparous cows. Overall, feeding blends of RUP and AA may improve the balance of AA for fresh cows fed high MP diets and improve concurrent and longer-term milk production in multiparous cows. However, with high MP diets, multiparous fresh cows require greater concentrations of fNDF than primiparous cows.

Effect of a high crude protein content diet during energy restriction and re-alimentation on animal performance, skeletal growth and metabolism of bone tissue in two genotypes of cattle.

The objective of this study was to investigate the effect of diet crude protein (CP) content and metabolisable energy (ME) intake on skeletal growth and associated parameters of growing steers prior to and during compensatory growth in weight and catch-up growth in skeletal elongation. The experiment was a factorial design with two cattle genotypes [Brahman crossbred (BX, 178 ± 6 kg) and Holstein-Friesian (HF, 230 ± 34 kg)] and three nutritional treatments; high CP content and high ME intake (HCP-HME), high CP content and low ME intake (HCP-LME) and low CP content and low ME intake (LCP-LME) with the ME intake of HCP-LME matched to that of LCP-LME. Nutritional treatments were imposed over a 103 d period (Phase 1), and after this, all steers were offered ad libitum access to the HCP-HME nutritional treatment for 100 d (Phase 2). Steers fed the high CP content treatment with a low ME intake, showed higher hip height gain (P = 0.04), larger terminal hypertrophic chondrocytes (P = 0.02) and a higher concentration of total triiodothyronine in plasma (P = 0.01) than steers with the same ME intake of the low CP content treatment. In addition, the low CP treatment resulted in significant decreases in bone volume (P = 0.03), bone surface area (P = 0.03) and the concentration of bone-specific alkaline phosphatase in plasma (P < 0.001) compared to steers fed the HCP-HME treatment. A significant interaction between genotype and nutritional treatment existed for the concentration of thyroxine (T4) in plasma where HF steers fed LCP-LME had a lower T4 concentration in plasma (P = 0.05) than BX steers. All steers with a restricted ME intake during Phase 1 demonstrated compensatory growth during Phase 2. However, HF steers fed the LCP treatment during Phase 1 showed a tendency (P = 0.07) for a greater LWG during Phase 2 without any increase in dry matter intake. Results observed at the growth plate and hip height growth suggest that catch-up growth in cattle may also be explained by the growth plate senescence hypothesis. Contrary to our initial hypothesis, the results demonstrate that greater CP intake during ME restriction does not increase compensatory gain in cattle during re-alimentation.

Sanguinarine improved nutrient digestibility, hepatic health indices and productive performance in laying hens fed low crude protein diets.

A major mean to minimize feeding costs and faecal nitrogen excretion on poultry farms is to decrease the supplied dietary protein content. This, however, is associated with the declines in productive performance and systemic health indices. Sanguinarine may improve protein efficiency via decreasing the intestinal amino acid decarboxylation and stimulating the tryptophan‐serotonin pathway. The present study was carried out to investigate the effects of dietary supplementation of sanguinarine on the performance, egg yolk biochemical parameters, serum enzyme activities, nutrient digestibility, ovarian follicles, and hepatic health indices in laying hens fed decremental levels of crude protein (CP). For this purpose, 180 laying hens were allocated into nine dietary treatments with four replicates of five birds each. The experimental treatments consisted of three levels of CP (85.0%, 92.5%, and 100% of Hy‐Line W‐36 manual recommendation) and three levels of sanguinarine (0.00, 3.75, and 7.50 mg/kg) in a 3 × 3 factorial arrangement administered during a 70‐day feeding trial. Results showed that the decremental levels of CP led to significant increases in serum aspartate aminotransferase (p < .05), alanine aminotransferase, and alkaline phosphatase (p < .01) activities, egg yolk cholesterol concentration (p = .064), and hepatic fat and malondialdehyde (MDA) contents (p < .05). It also caused the significant declines in ileal dry matter (DM) digestibility (p < .05) and eggshell strength (p < .05), and also tended to decrease CP digestibility (p = .071), Haugh unit (p = .057) and egg production percentage (p = .062). The interaction effects of the experimental factors indicated that dietary supplementation of sanguinarine, especially at 7.50 mg/kg, led to significant improvements in serum aspartate aminotransferase and alanine aminotransferase activities (p < .01), egg yolk cholesterol (p < .001) and triglyceride (p < .05) concentrations, eggshell strength (p < .001), Haugh unit (p < .05), hepatic fat (p < .001) and MDA (p = .059) contents, ileal DM and CP digestibility (p < .01) as well as egg production, egg mass and feed conversion ratio (FCR; p < .05) in birds receiving decremental levels of CP. Taken together, the results indicate that dietary administration of sanguinarine could enhance productive performance via improving nutrient digestibility, hepatic health indices and fortifying systemic antioxidant capacity in laying hens fed low‐CP diets.

Impacts of dietary protein on growth performance, feed utilization, amino acid profile, activities of digestive and amino acid metabolizing enzymes of the soft‐shelled turtle ( Pelodiscus sinensis )

The impacts of dietary protein on growth, body proximate composition, feed utilization, amino acid profile, digestive enzyme activity and amino acid metabolizing enzymes in soft-shelled turtles (Pelodiscus sinensis) (initial weight: 4.02 ± 0.06 g) were measured during an 8-week feeding trail. Six diets containing 8%, 18%, 28%, 38%, 48% and 60% (control group) fishmeal were formulated, which contained 14.38%, 20.41%, 26.19%, 32.23%, 37.63% and 45.23% protein respectively. Weight gain, mean feed intake, skirt ratio, pepsin activity of stomach, total amino acid of the muscle and crude protein levels of the whole body improved as dietary protein content increased from 14.38% to 26.19% but remained stable thereafter. The hepatosomatic index, feed conversion ratio, intestinal alpha-amylase activity, moisture content of the whole body and serum alanine transaminase and aspartate aminotransferase activity decreased with increasing protein content up to 26.19% and then plateaued. The protein productive value and protein efficiency ratio decreased as protein content increased. Intestinal lipase activity and crude lipid levels of the whole body were unaffected by dietary protein level. Hepatic alanine transaminase and aspartate aminotransferase activity first significantly increased with increasing protein but remained stable at protein content ≥26.19%. The optimum dietary protein level for soft-shelled turtles was in the range of 27.36%–28.46% based on weight gain, ALT activity and AST activity results.

The Digestive Function of Pseudoplatystoma punctifer Early Juveniles Is Differentially Modulated by Dietary Protein, Lipid and Carbohydrate Content and Their Ratios.

Pseudoplatystoma punctifer is an Amazonian catfish highly appreciated for its high flesh quality, size, and commercial value. Its aquaculture is pursued to satisfy the demands of an increasing population in the region. However, knowledge of the nutritional needs during the early life stages is necessary for improving growth and reducing the incidence of cannibalism, factors that limit the success of its commercial farming. This study aimed at evaluating the influence of four diets containing different protein and lipid levels (30:15, 30:10, 45:15, or 45:10 in %) in the digestive physiology and performance of early juveniles. The results showed that the dietary protein:lipid as well as carbohydrate levels and ratios influenced differently the whole-body proximate composition, the digestive physiology and development, and hence growth and survival. The 45:15 diet promoted the best growth, survival, and the most rapid development of the digestive system, as shown at histological (higher number of hepatocytes, goblet cells in the anterior intestine and enterocytes in all intestinal portions, and longer folds in the posterior intestine), molecular (highest amylase, lipoprotein lipase, phospholipase, trypsinogen, and pepsinogen gene expression), and biochemical (highest lipase and pepsin activities and higher alkaline phosphatase:leucine alanine peptidase activity ratio) levels. Lipids were favored over carbohydrates as source of energy, with lipids promoting a protein-sparing effect at adequate energy:protein ratio. Carbohydrate content higher than 25% was excessive for this species, leading to unbalanced lipid metabolism and fat deposition in the liver.

Functional amino acid supplementation, regardless of dietary protein content, improves growth performance and immune status of weaned pigs challenged with Salmonella Typhimurium.

High dietary protein may increase susceptibility of weaned pigs to enteric pathogens. Dietary supplementation with functional amino acids (FAA) may improve growth performance of pigs during disease challenge. The objective of this study was to evaluate the interactive effects of dietary protein content and FAA supplementation above requirements for growth on performance and immune response of weaned pigs challenged with Salmonella. Sixty-four mixed-sex weanling pigs (13.9 ± 0.82 kg) were randomly assigned to dietary treatments in a 2 × 2 factorial arrangement with low (LP) or high protein (HP) content and basal (AA-) or FAA profile (AA+; Thr, Met, and Trp at 120% of requirements) as factors. After a 7-d adaptation period, pigs were inoculated with either a sterile saline solution (CT) or saline solution containing Salmonella Typhimurium (ST; 3.3 × 109 CFU/mL). Growth performance, body temperature, fecal score, acute-phase proteins, oxidant/antioxidant balance, ST shedding score in feces and intestinal colonization, fecal and digesta myeloperoxidase (MPO), and plasma urea nitrogen (PUN) were measured pre- and postinoculation. There were no dietary effects on any measures pre-inoculation or post-CT inoculation (P > 0.05). Inoculation with ST increased body temperature and fecal score (P < 0.05), serum haptoglobin, plasma superoxide dismutase (SOD), malondialdehyde (MDA), PUN, and fecal MPO, and decreased serum albumin and plasma reduced glutathione (GSH):oxidized glutathione (GSSG) compared with CT pigs (P < 0.05). ST-inoculation reduced average daily gain (ADG) and feed intake (ADFI) vs. CT pigs (P < 0.05) but was increased by AA+ vs. AA- in ST pigs (P < 0.05). Serum albumin and GSH:GSSG were increased while haptoglobin and SOD were decreased in ST-inoculated pigs fed AA+ vs. AA- (P < 0.05). PUN was higher in HP vs. LP-fed pigs postinoculation (P < 0.05). Fecal ST score was increased in ST-inoculated pigs on days 1 and 2 postinoculation and declined by day 6 (P < 0.05) in all pigs while the overall score was reduced in AA+ vs. AA- pigs (P < 0.05). Cecal digesta ST score was higher in HP vs. LP-fed pigs and were lower in AA+ compared with AA- fed pigs in the colon (P < 0.05). Fecal and digesta MPO were reduced in ST pigs fed AA+ vs. AA- (P < 0.05). These results demonstrate a positive effect of FAA supplementation, with minimal effects of dietary protein, on performance and immune status in weaned pigs challenged with Salmonella.