Effect of phytase enzyme on growth performance, serum biochemical alteration, immune response and gene expression in Nile tilapia

Effects of phytase enzyme supplementation on growth performance, intestinal morphology and metabolism in Nile tilapia (Oreochromis niloticus)

Phytase is crucial in enhancing the bioavailability and release of phosphorus and other nutrients bound to phytic acid, making them more bioavailable for animal absorption. This study was carried out to inspect the effect of supplementing low phosphorus (P) diet with di-calcium phosphate (DCP) and liquid phytase enzyme (LP), which contains 1500 FTU/kg, on growth performance, intestinal morphometry, proximate body chemical composition, blood profile, immunity status, liver mitochondrial enzyme activities, the expression response and economic returns of Nile tilapia (Oreochromis niloticus). Three triplicate groups of fish (initial weight 5.405 ± 0.045 g, N = 90) were fed on three different diets for 90 days. The first was a control diet with zero DCP; the second was a control diet supplemented with 0.71% DCP; the third was a control diet supplemented with 0.03% LP. The groups were designated as CG, DCP and LP, respectively. Results showed that LP induced considerable improvements (p < 0.05) in FBW, body weight gain, weight gain rate, specific growth rate, HIS, viscero-somatic index, spleen-somatic index, feed conversion ratio, blood parameters and the histomorphometry assessment of intestinal villi absorptive capacity, compared with the other groups. Also, whole-body protein and lipid contents pointedly (p < 0.05) increased by LP, compared with the DCP group. A positive response (p < 0.05) to the phytase enzyme was noted in complexes I, III and IV of the mitochondrial liver complex enzyme activity. Likewise, the relative gene expression levels of (GHr-1, IGF-1, FAS and LPL) were notably (p < 0.05) upregulated by phytase enzyme, associated with DCP and control groups. Further, phytase recorded the highest total return and profit percentage. It can be concluded that Nile tilapia benefits from using phytase enzyme 1500 FTU/kg at 0.03% without adding DCP in terms of good performance and profits.

Effects of phytase inclusion in diets containing rice protein concentrate (RPC) on the nutrient digestibility, growth and chemical characteristics of rohu (Labeo rohita)

The objective of the current study was to assess the impact of dietary phytase supplementation on Labeo rohita fingerlings and to examine the effects on growth, nutrient digestibility and chemical characteristics of diets containing rice protein concentrate (RPC) as a major protein source. Six experimental diets were made, i.e., a positive control (fishmeal-based diet with no phytase), FM0; a negative control (RPC-based diet with no phytase), RPC0; and four supplemental phytase levels (250, 500, 1000, and 2000 FTU/kg). Fingerlings with an average weight of 9.42 ± 0.02 grams (mean ± SD) were randomly distributed into six experimental groups of three replicates, each containing 25 fish per tank (75 liters of water), provided with experimental diets at a rate equivalent to 5% of their body weight for 90 days, and uneaten feed was collected after 2 hours to determine feed consumption. The feces were collected before feeding to estimate digestibility. Phytase in combination with the RPC-based diet significantly (p < 0.05) enhanced phytate phosphorus in vitro hydrolysis; growth performance; nutrient (crude protein, crude fat, moisture and gross energy) and mineral (P, Ca, Mg, Na, K, Zn, Mn and Cu) digestibility; digestive enzyme (protease, lipase and amylase) activity; and mineral deposition up to 1000 FTU/kg phytase. However, the hepatosomatic and viscerosomatic indices and carcass composition were not influenced (p > 0.05) by phytase supplementation. Increasing phytase supplementation in the RPC-based diets led to a significant (p < 0.05) decrease in the serum biochemical parameters (alkaline phosphatase activity, aspartate aminotransferase, alanine aminotransferase), which resulted in improved liver health. In conclusion, phytase-supplemented RPC-based diets improved the growth, mineral/nutrient digestibility, digestive enzymes, serum biochemistry, and mineral deposition of L. rohita fingerlings up to 1000 FTU/kg. Broken line regression analysis revealed that the optimum phytase concentration in the RPC-based diet for L. rohita was 874.19 FTU/kg.

The effects of dietary microbial 6-phytase on growth parameters, intestinal morphometric properties and selected intestinal genes expression in rainbow trout (Oncorhynchus mykiss, Walbaum 1876)

This study investigated the effects of dietary 6-phytase, produced by a genetically modified Komagataella phaffii, on growth performance, feed utilisation, flesh quality, villus morphometric properties, and intestinal mRNA expression in rainbow trout. Six iso-nitrogenous, iso-lipidic, and iso-caloric diets were formulated and fed to triplicate groups of juvenile rainbow trout weighing 32.57 ± 0.36 g (mean ± SD) for 90 days. The dietary treatments included two positive controls (PC), one formulated with 400 g/kg of fish meal named T1, and the other formulated with 170 g/kg of fish meal plus 1% avP derived from monocalcium phosphate named T2. The remaining dietary treatments consisted of a negative control (NC) formulated with 170 g/kg of fish meal (T3), NC+ 750, NC+ 1500, and NC+ 3000 OTU/kg levels of phytase designated as T4, T5, and T6 diets respectively. Compared to T1, weight gain (WG) increased by 16.29, 13.71 and 11.66% in T4, T5 and T6, respectively (p < 0.05). Feed conversion ratio (FCR) was lowered by 3.2 and 0.8% in T4 and T5 compared to T1 (p < 0.05). WG, feed intake (FI), FCR, final body length, bone ash, bone ash P, and intestinal morphometry were negatively affected in T3 fed fish (p < 0.05). Whole-body fish nutrient, bone ash, bone ash phosphorus (P) compositions and mucosal villus morphometric properties improved in rainbow trout fed diets supplemented with phytase dose ranging from 750-3000 OTU. Bone ash increased by 6.12% in T5 compared to T1 (p < 0.05). Phytase inclusion enhanced the profitability of feeding juvenile rainbow trout such diets as it reduced the feed price and economic conversion rate. Dietary inclusion of phytase down-regulated mRNA expression of genes responsible for fatty acid synthesis and lipogenesis in juvenile rainbow trout. Dietary phytase up-regulated the mRNA expression of genes (SLC4A11 and ATP1A3A) responsible for nutrient uptake and down-regulated intestinal expression of MUCIN 5AC-like genes (mucus secreting genes) in juvenile rainbow trout. Along with improving performance parameters, the inclusion of phytase in rainbow trout diet containing plant-based protein sources, can preserve intestinal morphology by regulating the mRNA expression of genes responsible for fatty acid synthesis, lipogenesis and nutrient uptake and transport.

Investigation of dietary exogenous protease and humic substance on growth, disease resistance to Flavobacterium covae and immune responses in juvenile channel catfish (Ictalurus punctatus)

Many bacterial pathogens impact the US catfish industry, and disease control can be challenging for producers. Columnaris disease in channel catfish, Ictalurus punctatus, is primarily caused by Flavobacterium covae (formerly F. columnare). Immunostimulants may enhance nonspecific immune responses and offer an alternative to antibiotic treatments in catfish. Furthermore, dietary protein sources and inclusions are also essential to fish health and nutrition and may enhance overall fish performance in pond culture. The current project evaluated two immunostimulants: a protease complex (PC) and a humic substance (HS) derived from a reed-sedge peat product. A 60-day trial examined the effects of five diets on growth performance, immune response and resistance to experimental F. covae infection in channel catfish. Diets included a high-quality fishmeal diet (32%; CF32), a high-protein soy-based diet (32%; C32), a low-protein soy-based diet (28%; C28; predominately used in industry), a low-protein soy diet supplemented with C28 + PC at 175 g metric ton^-1 and C28 + HS in a low-protein diet at 23 g metric ton^-1 . Following feeding for 60 d, juvenile channel catfish were sampled for growth performance and baseline health indicators (n = 3; body mucus, blood for sera, kidney and spleen). A subset of fish was then subjected to an immersion-based in vivo challenge trial with F. covae (ALG-00-530; 10⁶  CFU mL^-1 exposure). At 60d post-initiation, there were no dietary differences in the relative growth rate (p = .063) or thermal growth coefficient (p = .055), but the 32% diets generally appeared to perform best. Post-challenge, the C32 group's mortality was higher than the C28 + PC (p = .006) and C28 + HS diets (p = .005). Although not significant, the C28 and CF32 groups also demonstrated higher mortality compared to both PC and HS diets. Sera lysozyme concentration was found to increase following pathogen challenge (p < .001) and in comparison with mock-challenged catfish (p < .001). Elevated expression levels of proinflammatory cytokines (il-1β, il-8, tnf-α and tgf-β) were observed at trial midpoint and post-infection when compared to 60d. The C28 treatment was found to have lower tnf-α expression than the C28 + PC (p = .042) and C28 + HS (p = .042) groups following exposure to F. covae. These challenge data suggest that the immunostimulants (PC and HS) in plant-based protein may be beneficial in protecting against F. covae when offered in low-protein channel catfish diets.

Effects of dietary supplementation with microbial phytase on the growth, bone minerals, antioxidant status, innate immunity and disease resistance of African catfish fed on high soybean meal-based diets

The microbial phytase, derived from Buttiauxella gaviniae, Yersinia mollarettiv and Hafnia spp., is proven to be safe for avian and porcine feeding and promotes their overall growth performance. Here, we have evaluated microbial phytase's effects on the growth, bone mineral content, antioxidant status, immune responses and the resistance of African catfish (Clarias gariepinus) fed with high soybean meal-based diets against Aeromonas hydrophila infection. Five isonitrogenous diets (40% protein) were supplemented with different levels of microbial phytase ranging from 0 as a control to 250, 500, 750 and 1000 FTU/kg diet. African catfish (n = 300; 8.5 ± 0.3 g) were allocated in 15 50-L tanks (in triplicates) and were fed on the prepared tested diets for 12 weeks. After the end of the feeding period of 12 weeks, 10 fish from each replicate was intraperitoneally infected with A. hydrophila (0.5 × 10⁵ CFU/ml) and monitored for 14 days. Dietary phytase levels linearly and quadratically improved the growth performance of African catfish and stimulated feed intake. Bone levels of calcium, phosphorus, magnesium and zinc were also positively modulated in phytase-fed fish, especially at 750-1000 FTU/kg diet. Similarly, counts of red and white blood cells as well as haemoglobin, packed cells volume, platelets, lymphocytes and heterocytes were significantly modulated in all fish fed with phytase-supplemented diets. Higher levels of serum total protein, albumin and globulin were also observed in fish fed with a 750-1000 FTU/kg diet of phytase. Conversely, aspartate and alanine aminotransferase activities were lower in fish fed with a 750-1000 FTU/kg diet of phytase, compared to those fed the control diet. Moreover, antioxidant enzymes (superoxide dismutase, catalase and glutathione peroxidase), reduced glutathione levels and immune responses (lysozyme, respiratory burst, protease and alkaline phosphatase activities) biomarkers were linearly and quadratically elevated, while malondialdehyde values were linearly and quadratically decreased in fish groups fed with phytase-based diets. After administering A. hydrophila, 60.0% of the fish fed the control diet perished, while no mortalities were observed in fish fed with 750-1000 FTU/kg diets. Taken together, the current study reveals that dietary phytase could improve the growth performance, blood profile, bone mineralization, antioxidant activities, immunity and overall protection of African catfish against A. hydrophila infection. Dietary phytase may be efficiently used in the feeding of African catfish to enhance their overall performance and mitigate health conditions with optimum level of 900 FTU/kg diet.

Effects of phytase supplementation of high-plant-protein diets on growth, phosphorus utilization, antioxidant, and digestion in red swamp crayfish (Procambarus clarkii)

Fish meal is increasingly being replaced by plant protein raw materials, meanwhile, it brings phytic acid, which combines with phosphorus to form phytate phosphorus and leads to a low utilization rate of phosphorus in shrimp. To solve this problem, this study investigated the effects of phytase supplementation on growth performance, phosphorus utilization, antioxidants, and digestion in red swamp crayfish (Procambarus clarkii). Crayfish (initial mean weight: 8.69 ± 0.15 g, N = 324) were randomly divided into six groups each with three replicates of 18 individuals each, and hand-fed for 8 weeks with one of six experimental diets (50 and 490 g kg^-1 animal and plant protein raw material, respectively): negative control (NC; 11.0 g kg^-1 phosphorus), positive control (PC; 15 g kg^-1 NaH₂PO₄ added to NC; 14.7 g kg^-1 phosphorus), and phytase supplementation diets (P1-P4: 0.1, 0.2, 0.4, and 0.6 g kg^-1 phytase added to NC, respectively). The feeding trial was performed in a micro-flow water culture system. P2 showed a significantly higher weight gain rate (WGR), specific growth rate, protein efficiency ratio, and protein retention efficiency (PRE) but showed the lowest feed conversion ratio (FCR) than other groups. Broken-line regression analyses using WGR, FCR, and PRE as evaluation indices showed that the optimal dietary phytase supplementation level was 0.233, 0.244, and 0.303 g kg^-1, respectively. P2 showed the highest crude protein content of whole crayfish and abdominal muscle, and phosphorus deposition rate, which was significantly higher than that in NC and PC. P3 showed the highest calcium and phosphorus contents in whole crayfish and phosphorus content in abdominal muscle, and calcium and inorganic phosphorus content in serum, which were significantly higher than those in NC. P3 showed significantly lowest serum alkaline phosphatase, alanine aminotransferase, aspartate transaminase activities, malondialdehyde content in hepatopancreas, and highest catalase activity, which were significantly lower and higher, respectively, than those in NC and PC. In summary, the addition of 0.2-0.4 g kg^-1 phytase significantly improves the growth performance, feed utilization, digestive enzyme activity, and antioxidant of P. clarkii, which has a similar effect to the direct addition of NaH₂PO₄ at 15 g kg^-1 to the feed.

Effect of phosphorus on growth performance, intestinal tight junctions, Nrf2 signaling pathway and immune response of juvenile mirror carp (Cyprinus carpio) fed different α-ketoglutarate levels

Previous research has shown that dietary α-ketoglutarate (AKG) supplementation can promote growth performance, phosphorus metabolism, and skeletal development of juvenile mirror carp (Cyprinus carpio) fed low phosphorous diets. In the current study, we tested the hypothesis that 1% AKG dietary supplementation reduces the dietary phosphorus requirements of juvenile mirror carp. A total of 12 experimental isoproteic and isolipidic diets containing available phosphorus levels of 0.21%, 0.38%, 0.55%, 0.72%, 0.89%, and 1.07% dry matter with either 0 or 1% AKG supplementation were used in the study. A total of 1080 juvenile fish of similar initial weight (0.90 ± 0.03 g) were selected and randomly assigned to 36 tanks. There were three replicates for each experimental group, with a density of 30 fish per tank. Fish were fed to satiation for 8 weeks. The results indicated that fish fed the diet supplemented with 1% AKG showed a significant increase in final body weight (FBW), weight gain rate (WGR), feed intake (FI) and phosphorus intake (PI) compared to the diet without AKG (P < 0.05). FBW and WGR increased significantly with increasing available phosphorus levels from 0.21% to 0.89% (P < 0.05). The mRNA expression of ZO-1, claudin 11, and occludin was significantly increased by dietary AKG and phosphorus (P < 0.05). The mRNA expression of Nrf2, GPx1a, and CAT in the Nrf2 signaling pathway was significantly increased by dietary AKG and phosphorus (P < 0.05). The expression levels of IL-10 and TGF-β2 were significantly increased by dietary AKG and phosphorus, but the expression levels of IL-1β, IL-8, IL-10, TNF-a and NF-κB were significantly decreased with dietary AKG and phosphorus supplementation (P < 0.05). Based on second-order polynomial regression analysis of WGR against dietary phosphorus levels, the optimal dietary phosphorus level was found to be 0.79% of dry feed for juvenile mirror carp fed a diet with 1% AKG supplementation and 0.93% of dry feed without AKG supplementation. This study confirmed that AKG supplementation can reduce the phosphorus requirements of juvenile mirror carp by promoting growth performance, intestinal tight junctions, Nrf2 signaling pathways and immune response.

Supplementation of Microbial Phytase with Safflower Meal in Rainbow Trout (Oncorhynchus mykiss): The Effects on Growth, Digestibility, Environmental, and Serum Biological Parameters

This study aimed to determine the effects of diets replacing soybean meal with safflower meal and phytase enzyme on feed utilization, growth performance, body composition, serum biological parameters, and environmental effects of rainbow trout (Oncorhynchus mykiss). To this aim, five different isonitrogenous (44%) and isocaloric (23 kJ) experimental feeds were formulated as follows: the control group (C) containing no safflower meal and enzyme; SFM10 and SFM20 groups containing 10% and 20% of safflower meal instead of soybean meal, respectively; and SFM10 ± P1000 and SFM20 ± P2000 groups containing 10% safflower meal and 1000 IU/kg phytase and 20% safflower meal and 2000 IU/kg phytase, respectively. Juveniles (12.57 ± 3.05 g average weight) were fed for 60 days. As a result, the best growth rate and feed conversion were recorded in the SFM20 ± P2000 group with 127.07 ± 7.73% and 1.13 ± 0.020, respectively p<0.05. On the contrary, total phosphorus in SFM20 ± P2000 group trial feed was 1.20 ± 0.02, while 0.70 ± 0.08 was found in feces that is the best result between other groups. ALP, LDH, TPROT, CHOL, and triglyceride levels were not statistically different among the experimental groups. ALT, AST, glucose, and albumin levels in serum resulted to be affected by different phytase levels but without any negative effect on fish growth and fish health status. Cholesterol level in the SFM10 ± P1000 group was the highest and positively affected growth and health status of this group. In conclusion, 20% safflower meal replacement along with 2000 IU/kg microbial phytase in feeds can be considered suitable for rainbow trout due to its sustainability and reduced environmental effects due to reduced phosphorous excretion.

Effects of Lycium barbarum polysaccharides on immunological parameters, apoptosis, and growth performance of Nile tilapia (Oreochromis niloticus)

In this study, the effect of Lycium barbarum polysaccharides (LBP) on immunological parameters, apoptosis, and growth performance of Nile tilapia (Oreochromis niloticus) was investigated. Dietary supplementation with LBP significantly increased complement 3 (C3) activity and promoted interleukin IL-1β gene expression in spleen tissue, significantly reduced apoptosis in spleen tissue, increased the specific growth rate (SGR), relative length gain (LG), and relative weight gain (WG) of Nile tilapia. However, dietary supplementation with LBP did not have a significant effect on serum alkaline phosphatase (AKP), malondialdehyde (MDA), and superoxide dismutase (SOD), blood constituents, apoptosis, or gene expression of IL-1β in liver tissue. Overall, the results showed that dietary supplementation with LBP increased the nonspecific immunity of Nile tilapia and reduced the apoptosis rate to promote growth and development. Thus, LBP has potential for use as a new immunostimulant in aquaculture.