Dietary Protein Level Research Articles

The Effect of Different Levels of Dietary Crud Protein During Different Age Stages on the Productive Performance of ROSS 308

An experiment at the poultry Field-Department of Animal Production/College of Agriculture / University of Anbar, to know the effect of dietary protein levels during different age periods on productive performance of broiler chicks. The experimental treatments included: T1: The control treatment with standard protein levels (22, 20 and 18%) for the starter, grower and finisher respectively, T2: raising the crude protein level to 24% for the first week of the starter stage to continue after that with a standard protein level until the fifth week to reduce then to 16% protein in the last week of the finishing stage, T3: The crude protein level was raised to 26% for the first week of the starter stage, to continue after that at with a standard protein level until the fifth week, to then be reduced to 14% protein in the last week of the finishing stage,T4: It started with a controlled level of crude protein, and in the first week of the growing stage, the protein level was raised to 24%, to continue after that at a standard protein level, and in the last week of the finishing site, the crude protein was reduced to 16% and T5: It began with a control level for crude protein and in the first week of the stage growing The protein level was raised to 26%, to continue after that at a record protein level, and in the last week of the finishing site, the crude protein was reduced to 14%. The results showed that the T1 and T2 treatments were significantly superior (p ≤ 0.05) and achieved the highest results of body weight in the first and second weeks.

Effects of High-Lipid Dietary Protein Ratio on Growth, Antioxidant Parameters, Histological Structure, and Expression of Antioxidant- and Immune-Related Genes of Hybrid Grouper

The hybrid grouper (♀ Epinephelus fuscoguttatus × ♂ E. lanceolatus) is a new species of grouper crossed from giant grouper (E. lanceolatus) as the male parent and brown-marbled grouper (E. fuscoguttatus) as the female parent. We hypothesized that optimal levels of dietary protein may benefit liver function. High-lipid diets are energetic feeds that conserve protein and reduce costs, and are a hot topic in aquaculture today. Therefore, the objective of the research is to investigated the effects of dietary protein level in high-lipid diets on serum and liver biochemistry, liver histology, and liver immune and antioxidant indexes and gene mRNA expression of the juvenile hybrid grouper (♀ Epinephelus fuscoguttatus × ♂ E. lanceolatus). Six iso-lipidic (161 g/kg) diets were formulated containing graded levels of protein (510 as control, 480,450, 420, 390 and 360 g/kg). Each treatment consisted of three replicates and 30 fish (6.70 ± 0.02 g) in one replicate. After an 8-week feeding experiment, the results indicated the following: (1) With the decreasing of dietary protein level, the specific growth rate (SGR) of groupers increased gradually and then decreased; SGRs of the 390 and 360 g/kg groups were significantly lower than other groups (p < 0.05). (2) In terms of serum and liver, the activity of antioxidant enzymes such as catalase (CAT) and superoxide dismutase (SOD), and the total antioxidant capacity (T-AOC) content, and the activity of immune enzymes such as lysozyme (LYS) and immunoglobulin (IgM) was significantly increased under the appropriate protein level. (3) Based on liver histology, we know that high or low dietary protein levels cause liver damage. (4) Dietary protein levels can significantly affect the mRNA expression levels of an anti-inflammatory factor gene (tgfβ), pro-inflammatory factor genes (il6, il8), heat shock proteins, and antioxidant and immune genes (hsp70 and hsp90, gpx, nrf2, keap1). It is concluded that the appropriate protein level can promote the growth performance of groupers, improve antioxidant activity and immune enzyme activity in serum and liver, and enhance the expression of immune genes.

Leucine improves dietary protein use efficiency by regulating protein synthesis by activating amino acid transporters and the mTORC1 pathways in Chinese mitten crab (Eriocheir sinensis)

Leucine plays a critical role in protein metabolism and energy homeostasis. This study determines whether leucine supplementation increases body protein synthesis in juvenile E. sinensis while consuming less protein than their requirements. It also investigates the effects of leucine on molecular mechanisms regulating protein synthesis. The 8-week growth trial included three dietary protein levels (22%, 30% or 38%) crossing three leucine levels (1.1, 2.5 or 5.0%). In the trial, 1440 crabs (0.40 ± 0.05 g) were allocated to a 3 × 3 factorial experiment with four replicates of 40 crabs each. The WG and SGR of the NP group were significantly higher than those of the LLP group when the diet contained 1.1% leucine (P < 0.05). The WG, SGR and whole-body protein content of the LP group were significantly higher than those of the LLP group with 2.5% leucine added to the diet (P < 0.05) but not significantly different from those of the NP group (P > 0.05). However, when 5% leucine was added to the diet, the whole-body protein content of the LP group was significantly higher than that of the LLP group (P < 0.05). Dietary leucine supplementation significantly improved growth performance, increased crude protein and decreased crude lipids in the crabs. When the diet contained 30% crude protein, the highest WG, SGR, PER and PRR appeared in the LP-2.5 group (P > 0.05). The PER and PRR of the NP-2.5 group were significantly higher than those of the NP-1.1 group (P < 0.05) and were not significantly different from those of the NP-5.0 group (P > 0.05). In addition, the whole-body protein content of the NP-2.5 group was significantly higher than that of the NP-1.1 and NP-5.0 groups (P < 0.05). Growth hormone and ecdysterone significantly increased with dietary protein levels. The highest growth hormone and ecdysterone in the hemolymph occurred in the 2.5% leucine groups. Moreover, leucine supplementation significantly increased lipase and amylase activity in the hepatopancreas (P < 0.05). The 2.5% leucine supplementation significantly increased CAT activity and decreased MDA in the hepatopancreas. Dietary leucine significantly increased hemocyanin in the hemolymph, and the expression of amino acid transporter genes was significantly increased with dietary leucine supplementation. The crabs fed 2.5% leucine supplementation had the highest gene expression of the mTOR pathway, indicating that dietary leucine significantly promotes amino acid transport and protein synthesis in the hepatopancreas and muscles. This study suggests that a low-protein diet can inhibit animal protein synthesis and decrease energy accumulation and growth. The 2.5% leucine supplementation in the 30% protein diet effectively could promote protein synthesis and utilization and improve crabs growth and protein utlization.

Comparison of Estimated Wild Giant Anteater (Myrmecopahaga tridactyla Linnaeus, 1758) Diets with Commercial Diets for Insectivores: Implications for Anteater Health

Using the stomach contents of 24 wild road-killed giant anteaters as proxies for their diet, we found that estimated wild diets were much lower in calcium (about ten times less) and phosphorus compared with manufactured feeds commonly fed to anteaters under human care. Indicators of soil consumption, such as ash, iron, and manganese were higher in the stomach contents than in either wild termites or manufactured diets, likely due to high levels of soil ingestion during feeding in the wild. Protein and fat levels in insects, stomach contents, and commercial diets all met carnivore recommendations. Both giant anteaters and tamanduas in managed care often develop hypercalcemia, perhaps because these taxa have an enhanced ability to retain calcium allowing them to survive on such low calcium diets. Results from this study indicate that, for anteaters in managed care, it is important to keep dietary calcium and vitamins D and K within recommended levels to prevent nutritional diseases such as hyper- and hypocalcemia and vitamin K deficiency.

The association between dietary inflammatory index and C-reactive protein in plasma and semen with semen quality: A cross-sectional study

Background: Infertility affects couples worldwide, with male factors being responsible for half of all cases.&#x0D; Objective: This study aimed to investigate the relationship between dietary inflammatory index (DII) and levels of C-reactive protein (CRP) in plasma and semen with the quality of semen in infertile males.&#x0D; Materials and Methods: In this cross-sectional study, 88 infertile men referring to Besat hospital, Tehran, Iran from December 2021-November 2022 were enrolled. A detailed questionnaire requesting information, and a 168-item semiquantitative food frequency questionnaire, were completed by participants. A food frequency questionnaire was used to calculate the DII. Additionally, semen and blood samples were collected from each participant for semen analysis and CRP-level assessment. Statistical analyses were performed to explore the association between DII and CRP levels with sperm quality. The correlation between DII and serum/semen CRP, besides assessing nutrients in each DII quartile group, was also explored.&#x0D; Results: A significant difference was observed between different DII quartiles considering sperm motility (p = 0.006) and morphology (p = 0.014). Post hoc study revealed a significant difference between the 1st and 2nd quartiles and the 1st and 4th quartiles of DII regarding sperm motility (p = 0.011, and 0.017 respectively) and a significant difference between the 1st and 2nd quartiles of DII considering sperm morphology (p = 0.009). A statistically significant inverse correlation was also observed between DII and sperm motility (p = 0.017). Carbohydrates and β-carotenes were significantly different between the 4 DII quartiles (p = 0.043 and p = 0.026, respectively). Finally, no significant correlation was observed between DII and CRP levels in blood and semen (p &gt; 0.05).&#x0D; Conclusion: The findings suggested a notable correlation between DII and semen quality; however, no significant association were observed between DII and CRP levels in blood and semen.&#x0D; Key words: Infertility, C-reactive protein, CRP, Inflammation, Sperm.

Assessment of hydrolysis of partially defatted black soldier fly larvae meal in diets for Nile tilapia Oreochromis niloticus

The chitin content of black soldier fly (Hermetia illucens) larvae meal (BSFM) is known to negatively affect its digestibility by fish. Nile tilapia (Oreochromis niloticus) tolerates well BSFM in the diet. However, chemical hydrolysis of dietary BSFM has not previously been attempted for this species. In this study, based upon a low-fishmeal control diet (40% crude protein and 9% crude fat), three levels of dietary protein, 25%, 50%, and 75%, were replaced by partially defatted BSFM, subjected or not to a prior hydrolysis treatment with formic acid and fed to Nile tilapia juveniles (initial body weight: 0.26 ± 0.00 g). The hydrolysis treatment did not modify greatly the proximate and amino acid composition of the diets, nor did it improve their in vivo apparent digestibility coefficients of dry matter or crude protein. However, it significantly increased the contents of arginine, taurine, and tyrosine, and significantly reduced the contents of methionine, valine, aspartic acid, and glutamic acid in muscle tissue of Nile tilapia. The hydrolysis treatment also decreased fish growth significantly. In contrast, for diets not containing hydrolyzed BSFM, not only did fish fed all three levels of protein replacement grow satisfactorily, but the diets with the levels of replacement of 50% and 75%, with final weights of 23.04 and 23.11 g, respectively, elicited superior fish performance, as compared to the diet with 25% replacement (final weight of 20.09 g). In addition, all three protein replacement diets produced significantly greater growth than the control diet (final weight of 17.72 g). The actual levels of inclusion of BSFM were, respectively, 14.11%, 28.21% and 42.33% of diet, the latter being the highest inclusion level of BSFM reported to date for successful growth of Nile Tilapia.

Dietary effects of protein and lipid levels on growth performance and flesh quality of large-size largemouth bass (Micropterus salmoides)

The aim of this trial was to investigate the effects of dietary protein and lipid levels on growth performance and flesh quality of largemouth bass (Micropterus salmoides). A 3 × 3 two-factor design was used, including three crude protein levels of 46%, 50%, 54% (P46, P50, P54) and three crude lipid levels of 8%, 12%, 16% (L8, L12, L16). Thus, a total of nine diets (P46/L8, P46/L12, P46/L16, P50/L8, P50/L12, P50/L16, P54/L8, P54/L12 and P54/L16) were prepared and fed to large-size largemouth bass with initial body weight of 109.7 g for 84 days. At the same dietary protein level, weight gain rate (WGR), protein efficiency rate (PER), viscerosomatic index and polyunsaturated fatty acids (PUFAs) percent in flesh showed an increasing trend with increasing the dietary lipid level, while feed conversion ratio (FCR) showed a decreasing trend. At P46 and P50, whole fish crude protein, muscle crude protein, total collagen content, hardness, springiness, chewiness and shear force increased, and steaming loss and freezing loss decreased with increasing the dietary lipid level, while the above indicators showed an opposite trend at P54. At P50, the protein retention (PR) of 16% crude lipid group was significantly higher than that in the 8% and 12% crude lipid groups (P < 0.05). At the same dietary lipid level, the 50% and 54% crude protein groups presented higher WGR and lower FCR than the 46% crude protein group. The P54/L16 group had the highest WGR (184.4%) and lowest FCR (0.92) among all the groups, but the P50/L16 group presented similar WGR and FCR to the P54/L16 group (P > 0.05). The P50/L16 group showed the highest PER, PR, whole fish protein, muscle protein, total collagen, PUFAs, muscle hardness, springiness, chewiness, shear force and the lowest steaming loss. In conclusion, based on growth performance and flesh quality, the appropriate dietary protein and lipid requirements for large-size largemouth bass were 50% and 16%, respectively.

Effect of biofloc technology in Farfantepenaeus aztecus culture: The optimization of dietary protein level on growth performance, digestive enzyme activity, non‐specific immune response, and intestinal microbiota

AbstractIn this study, a biofloc technology (BFT) based 90‐day feeding trial was performed to estimate the effects of four different dietary protein levels (290, 320, 350 and 380 g protein kg−1 diet; 29P, 32P, 35P, and 38P, respectively) on growth performance, digestive enzyme activity, non‐specific immune response, whole‐body proximate and fatty acid composition and intestinal microbiota of Farfantepenaeus aztecus. Final weight, weight gain, and specific growth rate improved with protein levels up to 35P per kg of diet, below which decreased significantly. Significant differences were observed in total hemocyte count, acid phosphatase, respiratory burst, glutathione, alkaline phosphatase, and total antioxidant capacity indices of shrimp fed different dietary protein levels. Protease, lipase, and amylase activities of shrimp were also affected by dietary protein levels. Proteobacteria was the most abundant bacteria among the groups. Overall, this study revealed that using 35% dietary protein is optimal in F. aztecus culture under environmentally friendly BFT conditions. Furthermore, these results provide a theoretical basis for future research on the evaluation of functional ingredients in diet for more economical production of F. aztecus at optimal protein levels.

Effects of Low Protein Diet on Production Performance and Intestinal Microbial Composition in Pigs.

In order to study the effects of a low protein diet on the production performance and intestinal microbiota composition of Hexi pigs, twenty-seven Hexi pigs with an initial body weight of 60.50 ± 2.50 kg were randomly divided into three groups (control group (CG), group 1 (G1), and group 2 (G2)) and participated in a 60-day finishing trial. The CG was fed a normal protein level diet with a protein level of 16.0%, and G1 and G2 were fed a low protein level diet with protein levels of 14.0% and 12.0%, respectively. The results showed that the low protein level diet had no significant effect on the production performance of Hexi pigs, compared with the CG, the slaughter rate of G1 and G2 increased by 2.49% (p > 0.05) and 6.18% (p > 0.05), the shear force decreased by 2.43% (p > 0.05) and 15.57% (p > 0.05), the cooking loss decreased by 24.02% (p < 0.05) and 21.09% (p > 0.05), and the cooking percentage increased by 13.20% (p > 0.05) and 11.59% (p > 0.05). From 45 min to 24 h and 48 h after slaughter, each group of pH decreased by 1.02, 0.66, and 0.42. For muscle flesh color, the lightness (L) increased by 13.31% (p > 0.05) and 18.01% (p > 0.05) in G1 and G2 and the yellowness (b) increased by 7.72% (p > 0.05) and 13.06% (p > 0.05). A low protein level diet can improve the intestinal flora richness and diversity of growing and finishing pigs. In the jejunum, the ACE index (899.95), Simpson index (0.90), and Shannon (4.75) index were higher in G1 than in the other groups, but the Chao1 index (949.92) was higher in G2 than in the remaining two groups. Proteobacteria, Actinobacteria, Euryarchaeota, and Verrucomicrobia were significantly higher in G1 than in the CG. The relative abundances of Lactobacillus, Terrisporobacter, and Megasphaera in G1 was significantly higher than in the CG (p < 0.05). In the cecum, the ACE index (900.93), Chao1 index (879.10), Simpson index (0.94), and Shannon (5.70) index were higher in G1 than in the remaining groups. The Spirochaetes in G2 were significantly higher than in the other groups, but the Verrucomicrobia was significantly lower than in the other groups. The relative abundances of Lactobacillus were higher in G1 and G2 than in the CG (p > 0.05). The relative abundances of unidentified_Clostridiales and Terrisporobacter in G2 were significantly lower than in the CG (p < 0.05). The relative abundance of Turicibacter in G1 was significantly lower than in the CG (p < 0.05). The relative abundances of other bacterial genera in G1 and G2 were increased by 30.81% (p > 0.05) and 17.98% (p > 0.05).

Effect of Miscellaneous Meal Replacements for Soybean Meal on Growth Performance, Serum Biochemical Parameters, and Gut Microbiota of 50-75 kg Growing Pigs.

This study was carried out to investigate the effects of miscellaneous meal (rapeseed meal, cottonseed meal, and sunflower seed meal) as a replacement for soybean meal on growth performance, apparent nutrient digestibility, serum biochemical parameters, serum free amino acid contents, and gut microbiota of 50-75 kg growing pigs. A total of 54 healthy growing pigs (Duroc × Landrace × Yorkshire) with initial body weights (BWs) of 50.64 ± 2.09 kg were randomly divided into three treatment groups, which included the corn-soybean meal group (CON), corn-soybean-miscellaneous meal group (CSM), and corn-miscellaneous meal group (CM). Each treatment included six replicates with three pigs in each replicate. Dietary protein levels were maintained at 15% in all three treatment groups. Additional rapeseed meals, cottonseed meals, and sunflower seed meals were added to the CSM group's meals to partially replace the 10.99% soybean meal in the CON group in a 1:1:1 ratio. Pigs in the CM group were fed a diet with a mixture of miscellaneous meals (7.69% rapeseed meal, 7.69% cottonseed meal, and 7.68% sunflower seed meal) to totally replace soybean meal. Our findings revealed that there was no significant impact of replacing soybean meal with miscellaneous meal on the ADG (average daily gain), ADFI (average daily feed intake), or F/G (feed-to-gain ratio) (p > 0.05) of growing pigs weighing 50-75 kg, nor on the crude protein, crude fat, or gross energy (p > 0.05) of the diet. On the other hand, compared to the CON group, the CM group exhibited significantly elevated serum alanine aminotransferase (ALT) and triglyceride (TG) levels (p < 0.05), while urea levels were significantly reduced (p < 0.05). No significant effect was observed on the serum free amino acid contents (p > 0.05) following the substitution of soybean meal with miscellaneous meal. A t-test analysis indicated that compared with the CON group, the CM group exhibited a significantly diminished abundance of Euryachaeota at the phylum level and augmented abundance of Desulfobacterota at the genus level. This study demonstrated that the miscellaneous meals (rapeseed meal, cottonseed meal, and sunflower seed meal) as a substitute for soybean meal in the diet had no significant negative effects on the growth performance, apparent nutrient digestibility, serum amino acid content, or diversity of fecal microbiota in 50-75 kg growing pigs. These results can be helpful in developing further miscellaneous meals (rapeseed meal, cottonseed meal, and sunflower seed meal) as functional alternative feed ingredients to soybean meal in pig diets.

The effect of sex and dietary crude protein level on nutrient transporter gene expression and cecal microbiota populations in broiler chickens

It is well known that male and female broilers differ in their growth performance and that many physiological factors contribute to this difference. The aim of this experiment is to investigate if there are differences between male and female broilers in cecal microbiota and nutrient transporter gene expression and if these differences play a role in the growth performance of broilers. The possible effect of protein level and its interaction with sex on microbiota and expression of the nutrient transporters were also investigated. Samples were collected from male and female birds fed either standard crude protein (SCP) or reduced crude protein diets (RCP) at the age of d 35. The experiment was designed as a 2 × 2 factorial arrangement of treatments consisting of 448 Cobb 500 broilers assigned to 32-floor pens with 4 treatments, 8 replicates, and 14 birds per pen for performance measurements. The factors were sex (male or female) and dietary crude protein (CP) level (standard or reduced). Body weight gain (BWG), feed intake and feed conversion ratio were recorded for each pen. Sex had a significant effect on BWG and FCR (P < 0.001) where males had a significantly higher BWG and better FCR compared to females. There was a significant interaction between sex and protein level on feed intake (FI) (P < 0.05), where male birds had a higher FI compared to female birds only when the birds were fed SCP but not RCP diets. There was a significant interaction between CP level and sex on the expression of CAT2 (P = 0.02) and PEPT2 (P = 0.026) where the genes were significantly upregulated in females but only when the RCP diet was fed. The RCP diet upregulated the expression of BoAT (P = 0.03) as a main effect. Female birds had significantly higher expression of the PepT-2 gene compared to the males. The alpha diversity of the cecal microbiota showed differences among the treatments. The Shannon diversity index was statistically higher (P = 0.036) for males fed the SCP diet and the Chao1 index for evenness was statistically higher (P = 0.027) in females fed the SCP diet. There was also a difference in the relative abundance of the 15 most common genera found in the cecal content of the broilers in this experiment and lastly, the differential composition of microbiota between the different treatments was also significantly different. This study suggests that chickens are able to compensate for a reduction in AA substrates when fed a low CP diet through the upregulation of certain AA transporters, females may adapt to low CP diets better by such upregulation compared to males, and lastly, sex has an effect on the cecal microbial population and these differences contribute towards the performance differences between male and female broilers.

80 Precision Nutrition to Enhance Poultry Performance and Health: the Role of Functional Amino Acids

Abstract Dietary amino acids drive the performance and meat yield of modern broiler strains, and as such, amino acids are among the most economically important nutrients in poultry feeds. At the same time, minimizing N excretion is an increasingly prevalent sustainability target for poultry producers across the world, and this goal is often pursued by feeding reduced crude protein diets. Moreover, poultry production has largely transitioned away from the use of in-feed antibiotic growth promoters, bringing attention to the impact of dietary protein and amino acid levels on the intestinal and overall health of broilers. In response to these dynamic scenarios, research from our lab and others has attempted to more precisely link dietary supply of essential and non-essential amino acids with their functional needs for broilers subjected to various pathogenic and environmental stressors. This presentation will address existing research and knowledge gaps related to functional amino acids in the context of precision nutrition to enhance poultry performance and health.

Effects of dietary corn and protein levels on physical properties of extruded feed pellets and growth performance of rainbow trout, Oncorhynchus mykiss

AbstractThe dietary protein levels and source of starch are factors in the economical production of feeds, which may change the physical quality of extruded pellets and the growth performance of fish. Eight feeds contained two protein levels and four levels of wheat flour substitutions by corn, as a 2 × 4 factorial experimental design, were produced by a twin‐screw extruder machine and fed to 800 rainbow trout. The results showed corn grain reduced expansion ratio, water stability at 120 and 260 min, starch gelatinization (SG), and apparent degradability, while bulk density (BD) and oil leakage of feed pellets increased. The high protein diets displayed the most BD, lower oil leakage, SG, and elastic modulus. The high protein feeds improved the final body weight, weight gain, specific growth rate, and feed conversion ratio (FCR) of fish. The corn grain reduced the FCR and promoted the trout's protein efficiency ratio. Lipid proportions of fish livers corresponded to hepatosomatic index and serum concentrations of aspartate aminotransferase and alanine aminotransferase. In general, corn, as the starch source in the high and low‐protein extruded feeds, can be replaced at levels of 33%–66% of wheat flour without adverse effects on the physical characteristics of feed pellets and the growth performance of rainbow trout.

Growth performance and feed utilisation of Australian hybrid abalone (Haliotis rubra × Haliotis laevigata) fed increasing dietary protein levels at three water temperatures.

Determining the macronutrient requirements for commercially valuable aquaculture species remains crucial for maximising production efficiency. Yet, such information is lacking for Australian hybrid abalone (Haliotis rubra × Haliotis laevigata), particularly with respect to life stage and water temperatures. The present study aimed to evaluate the effect of dietary protein inclusion level on the growth performance, nutrient utilisation and nutritional quality of juvenile (3·3 g) Australian hybrid abalone reared at three different temperatures representative of winter (12°C), average annual (17°C) and summer (22°C) grow-out periods and fed five diets containing graded dietary protein levels of 35, 38, 41, 44 and 47 %. Abalone growth increased with increasing water temperature with weight gains of approximately 100, 280 and 380 % of their initial weight at 12, 17 and 22°C, respectively. Furthermore, the present study clearly demonstrated that higher dietary protein inclusion levels (41 %) than those currently used commercially (35 %) would significantly improve the growth performance when water temperatures are ≥17°C without any adverse impacts on nutrient utilisation, nutrient deposition or nutritional quality of the abalone soft tissue. For example, at 22°C abalone fed a diet containing 41 % protein obtained a significantly higher weight gain percentage (421 %) compared with those fed a diet containing 35 % protein (356 %). Lastly, it is suggested that maintaining a dietary protein inclusion level of 35 % or implementing a 'least cost' feeding approach during cooler seasons, or where water temperatures are ∼12°C, may be beneficial, considering only marginal growth improvements were observed during these periods of slow growth.

47 Feeding Pigs with Low Crude Protein Diets: Impact of Pig Manure Nitrogen Content on Biogas Production and Digestate Quality

Abstract Lowering dietary crude protein levels is a nutritional strategy recognized to both decrease the use of high-impact feed ingredients and reduce nitrogen (N) excretion. Improved pig manure management practices can further mitigate the environmental impacts associated with pig production towards net-zero emissions. Anaerobic digestion (AD) is a promising technology for transforming pig manure into energy as biogas and into bio-based fertilizers (i.e., digestate from AD). However, little is known about the effects of pig manure N content on AD. Thus, this study aimed to evaluate the impact of pig manure N content on biogas production and digestate quality through the AD of manure from pigs fed low crude protein diets. Three pig manure N concentrations were tested: T1 = 5873, T2 = 5421, and T3 = 5149 total Kjeldahl nitrogen (TKN, mg/L). Throughout 5 sequential fed-batch cycles (25 ± 4 days/cycle), biogas production and its composition (CH4, CO2, and H2S) were measured, while raw manure and weekly digestate samples were analyzed for total solids (TS, %), volatile solids (VS, %), pH, chemical oxygen demand (COD, mg/L), TKN, and ammoniacal nitrogen (NH3-N, mg/L). In a temperature-controlled room (20 ± 1ºC), 6 digesters (3 treatments x 2 replicates) were operated as single-stage reactors to digest pig slurry (mixture of urine and feces, TS: 5.6%) inoculated with a liquid inoculum (TS: 2.3%) to improve manure-microbe interactions. Data were analyzed by ANOVA using PROC MIXED with repeated measures and comparison of means through the Tukey test (SAS software). In addition, both correlation and regression analyses were performed with R to evaluate the relationship among variables. Decreasing pig manure N content showed a tendency to reduce biogas (-20% in T3 vs T1; P = 0.0782) and methane (-22% in T3 vs T1; P = 0.0576) production per cycle, as shown in Table 1. Regarding biogas composition, CH4/biogas and CH4/CO2 decreased with N content (-3 and -4% in T3 vs T1; P ≤ 0.0082). There were strong positive correlations between the N content of pig manure and the amount of NH3-N (linear: r = 0.94, R2 = 0.88) and TKN (linear: r = 0.90, R2 = 0.81) present in the digestate at the end of each cycle. These results suggest that a reduction in pig manure N content reduces biogas production and its quality (ratio of CH4 to CO2). This latter variable is important for biogas efficiency; thus, reducing crude protein in pig diets may impair the production of biogas in AD. However, a decreased N content may cause less emissions into the environment, but when using the digestate as fertilizer, it may not entirely fulfill the N requirements of fast-growing crops for a given application rate.

Effect of alpha-ketoglutarate supplementation on growth, antioxidant capacity, gene expression and amino acid profile in Nile tilapia (Oreochromis niloticus) under varying protein diets

Protein is the most expensive component in aquafeed and emphasis is given to reduce dietary protein levels without compromising growth. Alpha ketoglutarate (AKG) promotes protein synthesis in fish and improves growth. The present experiment was conducted to investigate the effect of AKG with different dietary protein levels on growth, nutrient utilisation, antioxidant status and immunity in Nile tilapia (Oreochromis niloticus). Five diets were prepared with different levels of protein such as 20 (P20A), 25 (P25A), 30 (P30A) and 35 % (P35A) with 1 % AKG and 35 % protein without AKG (P35C). Nile tilapia fingerlings (300) were randomly stocked in fifteen 150 L capacity FRP tanks with 20 fingerlings (9.91 ± 0.06 g) in each. The fish were then fed with experimental diets twice daily for 60 days. The fish fed with P30A had significantly (P < 0.05) higher growth performance and nutrient utilisation. However, there was no significant (P > 0.05) difference in final body weight and weight gain of tilapia fed with P35C and P25Adiets. The feed conversion ratio (FCR) was significantly higher (P < 0.05) in P20A group and other groups showed alike (P > 0.05) FCR value. The whole body protein and lipid contents of final fish were significantly (P < 0.05) higher in P30A and P25A, respectively. The P25A, P30A and P35A showed increased (P < 0.05) activities of superoxide dismutase (SOD) and catalase (CAT). The activity of metabolic enzymes were also higher in higher protein levels with AKG (P30A and P35A). The expression level of growth gene insulin like growth factor 1 (IGF-1) was significantly up-regulated (P < 0.05) in the P30A. In addition, the relative expression levels of the pro-inflammatory factors tumour necrosis factor (TNF-α) were significantly (P < 0.05) lower in P30A, P25A, and P20A. Total amino acid profile of fish was higher in P35C group. In summary, the optimal choice for enhancing growth and health in Nile tilapia appears to be a diet comprising 30 % protein and 1 % AKG. However, diet of 25 % CP with AKG showed equivalent result in terms growth that of 35 % CP level without AKG. Hence, 25 % protein with 1 % AKG can effectively fulfil protein requirement in tilapia.

Optimal dietary protein level for the growth and metamorphosis of bullfrog (Lithobates catesbeianus) tadpoles

This study investigated the effects of dietary protein levels on growth performance, antioxidant capacity, digestive enzyme activity, and metamorphosis rate of the bullfrog (Lithobates catesbeianus) tadpoles. Seven isolipidic and isoenergetic diets were formulated with 24.61%, 28.49%, 33.74%, 37.50%, 44.06%, 48.39% and 53.92% crude protein. Triplicate replicates of tadpoles (growth stage 25 and 0.009 g) were fed with experimental diets two times daily for 11 weeks, and the daily feeding amount was 6.50% of the tadpole's body weight. Weight gain (WG), specific growth rate (SGR), the total antioxidant capacity (T-AOC) and catalase (CAT) activity in the liver, the intestinal trypsin activity (TPS) and metamorphosis rate at stage 42 of bullfrog tadpoles all increased with increasing dietary protein level from 24.61% to 44.06% and then decreased. Based on the second-order polynomial regression analysis of the weight gain and metamorphosis rate at stage 41 vs. dietary protein level, the optimal dietary protein level for bullfrog tadpoles was 42.49% and 46.50%, respectively. In conclusion, the optimum dietary protein level of bullfrog tadpoles was estimated to be 42.49%–46.50% of the diet.

Faecal metabolome responses to an altered dietary protein:carbohydrate ratio in adult dogs

High-protein diets may aid weight loss and weight maintenance programs in both humans and dogs, although the effect of dietary protein levels on gut metabolism and functionality has not been studied in depth. The current study aimed to investigate the effect of an altered dietary protein:carbohydrate ratio on gut function in adult dogs by means of faecal metabolomic fingerprinting. More specifically, functional metabolic differences in dogs fed a high-protein/low-carbohydrate (HPLC) vs. low-protein/high-carbohydrate (LPHC) diet were studied by equally allocating twelve clinically healthy (6 lean and 6 obese) Beagles into two groups in a cross-over design, with each group receiving two isocaloric diets for four weeks. The faecal metabolome revealed that different protein:carbohydrate ratio can influence host and/or gut microbiome metabolism and function, while no effect was observed on the body condition. Targeted analysis demonstrated that the HPLC diet significantly increased the concentration of indole, spermidine, and pipecolinic acid and decreased the concentration of azelaic acid, D-fructose, mannose, and galactose (p < 0.05). Multivariate modelling (OPLS-DA) of the untargeted faecal metabolome revealed distinctly different metabolomic profiles following the HPLC vs. LPHC diet, with 18 altered pathways. The HPLC diet influenced amino acid and lipid metabolism, potentially promoting weight loss and immune function, whereas the LPHC diet affected carbohydrate fermentation and may promote anti-oxidative function.

Glycerol monolaurate improves growth, lipid utilization and antioxidative status of white-leg shrimp, Penaeus vannamei fed with varying protein-lipid diets reared in inland saline water

Higher lipid at suboptimum dietary protein level can be a suitable approach to formulate cost-effective feed for cultured fish. However, excess lipid may cause metabolic burden to animals resulted in growth retardation with lipid deposition. Therefore, a feeding trial of 60 days was conducted to assess the effect of glycerol monolaurate (GML) supplemented in varying protein and lipid diets on growth, lipid utilization, antioxidant status and biochemical indices of white-leg shrimp, Penaeus vannamei juveniles reared in inland saline water (ISW). Accordingly, three hetero-lipidic (5–9% lipid), hetero-nitrogenous (30–36% CP), and hetero-energetic (379–400 Kcal DE/100 g) diets with three levels of GML (0%, 0.07% and 0.1%) were formulated for nine diets viz. P36L5G0 (36% CP, 5% lipid and 0% GML), P36L5G0.07 (36% CP, 5% lipid and 0.07% GML), P36L5G0.1 (36% CP, 5% lipid and 0.1% GML), P33L7G0 (33% CP, 7% lipid and 0% GML), P33L7G0.07 (33% CP, 7% lipid and 0.07% GML), P33L7G0.1 (33% CP, 7% lipid and 0.1% GML), P30L9G0 (30% CP, 9% lipid and 0% GML), P30L9G0.07 (30% CP, 9% lipid and 0.07% GML) and P30L9G0.1 (30% CP, 9% lipid and 0.1% GML). Five hundred and forty P. vannamei juveniles (4.02 ± 0.01 g) were randomly distributed following 3 × 3 factorial design. Highest (p < 0.05) weight gain. Specific growth rate, protein efficiency ratio, lipid efficiency ratio, whole body protein with lowest feed conversion ratio, whole body lipid, and hepatopancreas–somatic index was recorded in P33L7G0.1 group. Hepatopancreatic amylase and lipase activities increased (p < 0.05) significantly while protease activity decreased in relation to increased levels of dietary lipid. However, supplementing GML resulted in increased (p < 0.05) activity of all digestive enzymes and highest activity was found in 0.1% GML fed group. Lipid metabolic enzyme glucose-6-phosphate dehydrogenase and carnitine palmitoyltransferase-1 activities were found maximum (p < 0.05) in P33L7G0.1 group and lowest in P36L5G0 group. Hepatopancreatic and branchial superoxide dismutase and catalase activities showed a decreased (p < 0.05) and increased trend with dietary lipid levels, while GML reduced the activities and lowest activity recorded in P33L7G0.1 group. Shrimps of 9% lipid group exhibited highest serum malondialdehyde, glucose, cholesterol and triglyceride levels but 0.1% GML significantly showed the lowest levels that other groups. Higher hemocyanin and total protein observed in 33% dietary protein and 0.1% GML fed group. Therefore, 33% protein, 7% lipid with 0.1% GML is optimum for maximum growth performance, lipid utilization, whole body protein, and antioxidative status of white-leg shrimp, P. vannamei juveniles reared in ISW of 10 ppt.

Dietary protein regulates ovarian development through TOR pathway mediated protein metabolism in female Litopenaeus vannamei

The accumulation of nutrients in the gonads is closely related to reproductive capacity and quality of the larvae in the subsequent autotrophic stage of Pacific white shrimp, Litopenaeus vannamei. Nutrition is one of the important factors affecting the gonad development of aquaculture animals, dietary protein is utilized as the major component of vitellogenin through vitellogenesis, which acts as an indispensable nutrient in ovary development. Therefore, six different protein diets were formulate to contain 39.81%, 44.34%, 48.20%, 52.81%, 56.12% and 59.45%, respectively. A total of 540 shrimp (initial weight, 9.3 g) were distributed randomly into eighteen 250-L cylindrical fiber-glass tanks, with each diet assigned to 3 replicate tanks. The results showed Arg, His, Leu, Lys, Glu, Gly, Pro, total essential amino acids (ΣEAA) and total non-essential amino acids (ΣNEAA) in ovary were significantly influenced by dietary protein levels, and shrimps fed diet with 39.81% protein exhibited the lowest total amino acids composition in ovary among all treatments. The percentage of ovarian development in stages III-V was higher in shrimp fed diets with higher protein ( ≥ 48.20%) than those fed diets with lower protein. Shrimp fed diet with 52.81% protein had higher serum concentrations of vitellogenin (VTG), meanwhile, shrimp fed the diet with 52.81% protein had higher expression levels of vitellogenin 1 (vg1), vtg and vitellogenin receptor (vgr) in the ovaries than those fed the other diets. However, the highest concentrations of VTG in the hepatopancreas and ovaries were observed at shrimp fed diet with 52.81% protein. The expression levels of target of rapamycin (torc1), ras homologue enriched in brain (rheb), protein kinase B (akt), 4E-binding protein (4ebp) and phosphatidylinositol 3-kinase (pi3k) in ovary and hepatopancreas significantly up-regulated in shrimp fed diet with 52.81% protein. In conclusion, dietary 52.81% protein promoted the synthesis of exogenous vitellogenin in hepatopancreas and its transport to the ovary through serum, and also motivated the production of endogenous vitellinogen in ovary, and was involved in the regulation of ovarian development through TOR mediated protein metabolism of L.vannamei .