Interactions between maternal parity and feed additives drive the composition of pig gut microbiomes in the post‑weaning period

Background Nursery pigs undergo stressors in the post-weaning period that result in production and welfare chal-lenges.These challenges disproportionately impact the offspring of primiparous sows compared to those of mul-tiparous counterparts.Little is known regarding potential interactions between parity and feed additives in the post-weaning period and their effects on nursery pig microbiomes.Therefore,the objective of this study was to investigate the effects of maternal parity on sow and offspring microbiomes and the influence of sow parity on pig fecal microbi-ome and performance in response to a prebiotic post-weaning.At weaning,piglets were allotted into three treat-ment groups:a standard nursery diet including pharmacological doses of Zn and Cu(Con),a group fed a commercial prebiotic only(Preb)based on an Aspergillus oryzae fermentation extract,and a group fed the same prebiotic plus Zn and Cu(Preb+ZnCu).Results Although there were no differences in vaginal microbiome composition between primiparous and mul-tiparous sows,fecal microbiome composition was different(R^(2)=0.02,P=0.03).The fecal microbiomes of primiparous offspring displayed significantly higher bacterial diversity compared to multiparous offspring at d 0 and d 21 post-weaning(P<0.01),with differences in community composition observed at d 21(R^(2)=0.03,P=0.04).When analyzing the effects of maternal parity within each treatment,only the Preb diet triggered significant microbiome distinc-tions between primiparous and multiparous offspring(d 21:R^(2)=0.13,P=0.01;d 42:R^(2)=0.19,P=0.001).Composi-tional differences in pig fecal microbiomes between treatments were observed only at d 21(R^(2)=0.12,P=0.001).Pigs in the Con group gained significantly more weight throughout the nursery period when compared to those in the Preb+ZnCu group.Conclusions Nursery pig gut microbiome composition was influenced by supplementation with an Aspergillus oryzae fermentation extract,with varying effects on performance when combined with pharmacological levels of Zn and Cu or for offspring of different maternal parity groups.These results indicate that the development of nursery pig gut microbiomes is shaped by maternal parity and potential interactions with the effects of dietary feed additives.

Phytogenic feed additives alleviate pathogenic Escherichia coli-induced intestinal damage through improving barrier integrity and inhibiting inflammation in weaned pigs

Background:This study was conducted to investigate the effects of each phytogenic feed additive(PFA;PFA1,bitter citrus extract;PFA2,a microencapsulated blend of thymol and carvacrol;PFA3,a mixture of bitter citrus extract,thymol,and carvacrol;PFA4,a premixture of grape seed,grape marc extract,green tea,and hops;PFA5,fenugreek seed powder)on the growth performance,nutrient digestibility,intestinal morphology,and immune response in weaned pigs infected with Escherichia coli(E.coli).Results:A total of 634-week-old weaned pigs were placed in individual metabolic cages and assigned to seven treatment groups.The seven treatments were as follows:1)NC;basal diet without E.coli challenge,2)PC;basal diet with E.coli challenge,3)T1;PC+0.04%PFA1,4)T2;PC+0.01%PFA2,5)T3;PC+0.10%PFA3,6)T4;PC+0.04%PFA4,7)T5;PC+0.10%PFA5.The experiments lasted in 21 d,including 7 d before and 14 d after the first E.coli challenge.In the E.coli challenge treatments,all pigs were orally inoculated by dividing a total of 10 mL of E.coli F18 for 3 consecutive days.The PFA-added groups significantly increased(P<0.05)average daily gain and feed efficiency and decreased(P<0.05)the fecal score at d 0 to 14 post-inoculation(PI).Tumor necrosis factorαwas significantly lower(P<0.05)in the PFA-added groups except for T1 in d 14 PI compared to the PC treatment.The T3 had a higher(P<0.05)immunoglobulin G and immunoglobulin A concentration compared to the PC treatment at d 7 PI.Also,T3 showed significantly higher(P<0.05)villus height:crypt depth and claudin 1 expression in ileal mucosa,and significantly downregulated(P<0.05)the expression of calprotectin compared to the PC treatment.Conclusions:Supplementation of PFA in weaned pigs challenged with E.coli alleviated the negative effects of E.coli and improved growth performance.Among them,the mixed additive of bitter citrus extract,thymol,and carvacrol showed the most effective results,improving immune response,intestinal morphology,and expression of tight junctions.

Essential oil and aromatic plants as feed additives in non-ruminant nutrition:a review

This paper summarizes the current knowledge regarding the possible modes of action and nutritional factors involved in the use of essential oils （EOs） for swine and poultry. EOs have recently attracted increased interest as feed additives to be fed to swine and poultry, possibly replacing the use of antibiotic growth promoters which have been prohibited in the European Union since 2006. In general, EOs enhance the production of digestive secretions and nutrient absorption, reduce pathogenic stress in the gut, exert antioxidant properties and reinforce the animal＇s immune status, which help to explain the enhanced performance observed in swine and poultry. However, the mechanisms involved in causing this growth promotion are far from being elucidated, since data on the complex gut ecosystem, gut function, in vivo oxidative status and immune system are still lacking. In addition, limited information is available regarding the interaction between EOs and feed ingredients or other feed additives （especially pro- or prebiotics and organic acids）. This knowledge may help feed formulators to better utilize EOs when they formulate diets for poultry and swine.

Effects of Different Feed Additives on Fur Production Performance of Rex Rabbit

[ Objectivel To investigate the effects of three different levels of feed additives on fur production performance of Rex rabbit. [ Method] A total of 60 healthy American strain Rex rabbits at the age of 60 d （female：male =1：1 ） were randomly divided into group I, group II and group III. The Rex rabbits in the group I were fed basal diet containing nutritional substances; those in the group II were fed basal diet containing nutdtionai substances and Chinese herbal additive; and those in the group III were fed basal diet containing nutritional substances, Chinese herbal additive and enzyme. The trial lasted for 100 d. After slaughtering, the fur area, fur thickness, wool density, wool fineness and coarse wool rate were determined. [Result] The fur production performance of group III was significantly higher than that of group I （ P 〈 0.05）. There was no significant difference between group III and group II. [ Conclusion] Supplementing Chinese herbal additive and enzyme in diet can improve the fur production performance of Rex rabbit.

Level and characteristics of polychlorinated dibenzo-p-dioxins and dibenzofurans in feed and feed additives

Feed security is a prerequisite for safe animal food products.In this study,13 groups of feed and feed ingredients,totaling 2067 samples,were collected in the period of 2011 to 2014 from China.The highest mean level of polychlorinated dibenzo-p-dioxins and dibenzofurans（PCDD/Fs） was found in fish meals and shell powders,with a concentration of 60.35 ng/kg,followed by mineral origin materials.In terms of the toxicity equivalent concentration,the fish oil group showed the highest PCDD/F levels because of their bio-accumulation through the aquatic food chain,with an average concentration of 1.26 ng WHO-TEQ/kg,while the lowest level was observed in compound feed for chickens and pigs,with an average value of0.16 ng WHO-TEQ/kg.OCDD and OCDF were the predominant congeners in all groups except fish oils,in which the primary congeners were 2,3,4,7,8-PeCDF and 2,3,7,8-TCDF.For zinc chloride samples,different from other zinc-based compound samples,the main congeners were 1,2,3,4,6,7,8-HpCDF（17%）,1,2,3,4,7,8,9-HpCDF（15%）,1,2,3,4,7,8-HxCDF（12%） and OCDF（30%）.Considering toxicity equivalency factors,the dominant congeners were 2,3,4,7,8-PeCDF,1,2,3,4,7,8-HxCDF,2,3,7,8-TCDF and 1,2,3,7,8-PeCDD,and the contribution to the total TEQwas29%,16%,14%and 12%,respectively.Overall,2.1%（43 out of 2067） of all the analyzed samples exceeded the different individual ＇European Union maximum limited levels for PCDD/Fs.This study is beneficial for the determination of the status of contamination levels of feed and feed ingredients.

Effect of Chinese Herbal Feed Additive on Meat Quality of Rex Rabbit

[ Objective] The aim of this study was to provide a theoretical basis for population and application of Chinese herbal feed additive in the rex rabbit breeding. [ Methyl] 108 weaned -rex rabbits aged 40 days were divided into three groups with thirty -six each group. Group A were fed basal diet, while group B were fed basal diet supplemented with 0.3% Chinese herbal feed additive and group C were fed basal diet supplemented with 0.4% Chinese herbal feed additive. The meat quality indexes were measured when feeding to 150 age in days. [ Result] There was significant difference among pH value, water loss rate, storing loss rate and crude protein content in each group （P〈0.05）, but no significant difference was found in tenderness, cooking percentage, moisture content and crude fat content （ P 〉 0.05）. The total content of ami- no acids, essential amino acids and semi essential amino acids as well as main delicious amino acids was highest in group C accounting for 23.84%, 11.47% and 8.32% respectively, next came group B accounting for 20.94%, 10.64% and 6.81% respectively, and lowest in group C （ control group） accounting for 19.06%, 9.61% and 6.46% respectively. [ Conclusion] The Chinese herbal feed additive can improve meat quality of rex rabbit the best addition of 0.4%.

Effects of Herbal Feed Additive on Milk Production of Dairy Cows

[Objective] The aim of this study was to investigate the efficacy of the herbal feed additive Zengrujianniusan on the milk production of dairy cows. [Method] Thirty-two black-white lactating cows were randomly divided into four groups, and were fed with forage supplemented with 0 （control group）, 0.2%, 0.4% and 0.6% Zengrujianniusan for 60 d. During this period, the contents of fat, protein and non-fat solid in milk were measured every 20 d. [Result] The milk production of the cows whose forage was added with 0.2 %, 0.4 % and 0.6% Zengrujianniusan was 4.02%, 12.50%, 14.00% higher than that of the control （P〉0.05）. The herbal feed additive had no significant influence on the contents of fat, milk and non-fat solid in milk, but significantly reduced the number of somatic cells. [Conclusion] The study will provide reference for developing feed additives which is safe and non-toxic to cows and their milk.

Test of Feeding Dairy Cows with Chinese Herbal Additive for Improving Production and Quality of Milk

At Baiyin dairy farm, the Chinese herbal additive was added into feed which was then fed to dairy cows from August to October, 2014, and the changes in milk production and quality were observed. The test showed that the additive added into the feed had obvious milk-increasing effect, the milk production was im- proved by 12.67%-17.26%, and the milk quality was improved. The additive has the effects of preventing miscarriage, expelling parasite and preventing diseases. The nutritional components in the feed additive were determined, and the results showed that the contents of protein, crude fat, Ca and P in the additive were 12.29%, 2.66%, 1.8% and 0.22%, respectively.

Production Technology and Application of Slow-Release Non-protein Nitrogen Extruded Feed Additive

Slow-release non-protein nitrogen feed has a large market demand. It has a long research history, but its production technology needs further improvement in order to realize the industrial production of slow-release non-protein nitrogen extruded feed. By designing the best formula and using chelating and emulsifying process, the slow-release non-protein nitrogen extruded feed additives were produced. This product increases milk yield and improves milk quality, thus increasing economic efficiency.

Yeast Culture and Its Application in Feed

Yeast culture is a kind of green feed additive. It has been researched and applied widely in the feed industry. In this paper, the functions of yeast culture and its application in the actual production were discussed. It can be concluded that yeast culture has a great application prospect.

Effects of Nano Chinese Herbal Medicine Feed Additive on Growth Performance,Meat Quality and Disease Resistance of Chickens

[Objectives]To explore the effects of nano compound Chinese herbal medicine feed additive on growth performance,meat quality and disease resistance of chickens.[Methods]Chickens were fed with nano compound Chinese herbal medicine feed additive developed by Hunan Polytechnic of Environment and Biology,including 120 chickens in the treatment group and 120 chickens in the control group(CK).The growth performance indices(body weight gain,feed to gain ratio and slaughter index),meat quality indices(pH value,color,drip loss,shear force)and disease resistance indices(morbidity and mortality)of the chickens in the treatment and CK groups were recorded and determined,respectively.[Results]The inclusion of 2%nano compound Chinese herbal medicine feed additive in the diet significantly increased the growth rate,reduced the feed-to-gain ratio and improved the meat quality of the chickens.Supplementing Chinese herbal medicine could increase the pH value and reduce the drip loss and shear force of chicken meat.At the same time,the body's immune function,antioxidant level and resistance against diseases of the chickens fed with nano compound Chinese herbal medicine feed additive were improved.[Conclusions]The inclusion of nano compound Chinese herbal medicine feed additive in the diet can improve the growth performance,meat quality and disease resistance of chickens.

Phytogenic Feed Additive for Sows： Effects on Sow Feed Intake, Serum Metabolite Concentrations, IgG Level, Lysozyme Activity and Milk Quality

The objective of this study was to investigate the influence ofa phytogenic feed additive （PFA） to late-gestation （d 90） and lactation sows on their reproduction performance. Sixty Large White × Landrace primiparous sows were divided into four groups （fifteen sows per group）. The control group was fed with basal diet, the others were fed with basal diet supplemented with 0.02%, 0.04% and 0.06% PFA, respectively. Compared with the control, the sows in 0.04% PFA group had higher feed intake during lactation and higher litter weaning weight （P 〈 0.05）. At farrowing, glucose level in 0.04% PFA sows was higher than the control and sows in 0.02% PFA had the highest IgG content among the treatments （P 〈 0.05）. On day 7 of lactation, serum urea nitrogen contents were lower in response to PFA supplementation compared to the control （P 〈 0.05）. At the same time, sows fed the 0.06% PFA diet increased the lysozyme activity （P 〈 0.05）. The levels of milk lactose and IgG were increased in 0.02% and 0.04% PFA groups （P 〈 0.05）. In conclusion, feeding PFA improved sows and litter performance, serum metabolite concentrations, lgG level and lysozyme activity at postpartum and milk quality.

Effects of Cordyceps Feed Additive on Production Performance and Egg Quality in Laying Ducks

[ Objective ] To investigate effects of Cordyceps feed additive on growth performance, laying rate and egg quality in laying ducks. [ Method] A total of 270 healthy laying ducks were randomly divided into throe groups, 90 ducks in each group. The ducks in the control group, group I and group II were fed common basal diet, basal diet containing 10 g/kg Cordyceps feed additive and basal diet containing 40 g/kg Cordyceps feed additive, respectively. The trial lasted for 28 d. During the whole trial, the ducks were weighed and their growth was observed at an interval of 7 d. The exterior quality and the nutritive indexes of duck eggs were determined. [ Result] After experiments, the body weights of ducks in the group I and group II were increased and higher than that of the control group. In the group I and group II, the laying rate was increased by 1.07% and 2.15%, respectively; the egg weight was increased by 3.95% and 4.16%, respectively; and the feed to egg ratio was decreased by 2.54% and 4.23%, respectively. The egg shape and eggshell thickness were consistent between the control group and experimental groups. In the group I and group II, the protein content of the duck eggs was increased by 5.55% and 17.15%, respectively; the cholesterol content was decreased by 11.79% and 42.14%, respectively; the IgY level was increased by 13.20% and 27.97%, respectively; and the lecithin content was increased by 5.13% and 11.69%, respectively. [Condusion] The Cordyceps feed additive can increase the body weight and laying rate of laying ducks and improve the quality of duck eggs.

Effects of Ultrafine Comminution on the Dissolution of Active Ingredients from Compound Feed Additive of Strobilanthes cusia

[Objective] The research aimed to explore the effects of comminution technology on the dissolution of active components from compound feed additive of Strobi/anthes cusia. [Method] Using active component adenosine in principal herb S. cusia and chlorogenic acid in minister drug Lonicera japonica Thunb. as dissolution indices,the effects of ultrafine comminution on the dissolution degree of compound feed additive of S. cusia were analyzed. [ Result] The dissolution degree of adenosine and chlorogenic acid in ultra micro particles were obviously higher than that of common particles. Ultrafine comminution could significantly quicken the dissolution rate of adenosine and chlorogenic acid in compound feed additive of S. cusia, shorten the extraction time, avoid the breakage of active components in long-time extraction process,and meanwhile saved the energy greatly. [ Conclusion] The ultrafine comminution technology could obviously increase the dissolution degree of active components in compound feed additive of S. cusia.

Preparation of Dried Culture of Probiotic Rhizopus oryzae in Two Different Mediums as Feed Additive to Indigenous Chicken

Fungus Rhizopus oryzae has a probiotic potential, but the potency is not yet explored. Probiotics are usually used as feed additive, including to the chicken. Probiotic needs a suitable medium for their life. The aim of the study was to know which preparations can produce suitable medium for the growth of Rhizopus oryzae on the dried culture formed. The study used two preparations. Preparation 1 （a） consisted of rice bran （1 kg） and culture ofRhizopus oryzae on Potato Dextrose Broth （PDB medium） （500 mL）; then preparation 1 （b） consisted of corn grain （1 kg） and culture of Rhizopus oryzae on PDB medium （500 mL）. Preparation 2 （a） consisted of rice bran （1 kg）, culture of Rhizopus oryzae on Potato Dextrose Agar （PDA medium） （seven petri dishes） and was added with sterile distilled water （500 mL）; preparation 2 （b） consisted of corn grain （1 kg）, culture of Rhizopus oryzae on PDA medium （seven petri dishes） and was added with sterile distilled water （500 mL）. The culture of Rhizopus oryzae even both on PDB and PDA were 3 d of incubation. All preparations were incubated for 7 d then they were dried under the sun. Parameter evaluation was the growth performance of the fungus in the dried culture media. The growth performance was analyzed by microscopic analysis and the number of colony of the fungi in the two dried culture media. The results showed that from the macroscopic analysis, the sample of both dried culture media which were placed on PDA medium showed the growth of mycelia and spores of the same kind of fungus and it was proved by microscopic observation that the fruiting bodies （mycelia and spores） of that ftmgus was Rhizopus oryzae. The colonies number of the fungi from preparation 1 （a） and 1 （b） were 0,4 × 10 cfu/gr and 2.4 × 10^3 cfu/gr, respectively, and from preparation 2 （a） and 2 （b） were 1.3 × 10^5 cfu/gr and 8.3 ×10^2 cfu/gr, respectively. It could be concluded that the product of the dried culture of probiotic Rizopus oryzae from the preparation 2 with rice brand or corn grain mediums can be used as feed additive to indigenous chicken.

Modification of Campylobacterjejuni Broiler Colonization by a Feed Additive Composed of Encapsulated Organic Acids and Essential Oils

The objective of this study was to evaluate the effect of a novel feed additive on chicken intestinal colonization and carcass contamination by Campylobacterjejuni. The feed additive was composed of microencapsulated organic acids and essential oils （OA/EO）. The feed additive tested was provided by Jefo Nutrition Inc., St-Hyacinthe, Quebec, Canada. Day-old birds were separated into two rooms and subdivided into two groups. Chicken were fed with OA/EO or not fed with OA/EO until they reached 35 d of age. At 14 d of age, chickens received an oral suspension of two well characterized C. jejuni strains, depending on the room they were housed in. The levels of C. jejuni were periodically monitored in the caecum and on the carcasses. C. jejuni colonization was further characterized by the use of high-resolution melt analysis of the C. jejuniflaA gene （HRM-flaA）. The effect of the feed additive was strain-dependent. In room two, the feed additive had no effect on the caecal counts. In room one, at 35 d of age, caecal C. jejuni counts were higher with OA/EO, as opposed to carcasses counts which were lower in the treated group. The HRM-flaA analysis showed that an amplification profile was predominant in birds fed with OA/EO at 35 d of age in room one, suggesting the selection of a C. jejuni strain. In conclusion, the OA/EO seemed to be effective to reduce C. jejuni levels but this effect appeared strain dependent.

Effect of Wolfberry Polysaccharide Additive Premixed Feed on Fattening Effect of Tan Sheep

[Objectives]This study was conducted to explore and rationally use the effective value and nutritional components of wolfberry polysaccharide to provide a basis for the use of new feed resources.[Methods]The premixed feed prepared with the wolfberry polysaccharide additive was applied to fattening Tan sheep in Ningxia,and the effect of the wolfberry polysaccharide additive on the fattening Tan sheep was analyzed,so as to provide technical support for the rational utilization of the wolfberry polysaccharide resources.The study adopted a single-factor comparison method,selecting 84 tan sheep in the fattening period with conform gender,feeding management,weight,age,and physiological status,which were divided into 2 test groups and 1 control group,28 in each group.[Results]Within 90 d,the weight gain of the group with 0.1%wolfberry polysaccharide additive increased by 6.98%,showing a significant difference(P<0.05),and the feed conversion ratio decreased by 9.66%,which was significant as well(P<0.05).The gross profit of this group was 125.76 yuan,which was higher than the control group by 57.52 yuan.The group with 0.2%wolfberry polysaccharide additive increased the weight gain by 8.63%,which was significant(P<0.05),and the feed conversion ratio decreased by 10.80%,which was significant as well(P<0.05).The gross profit of group 2 was 125.76 yuan,which was higher than the control group by 63.41 yuan.There were no significant differences in weight gain,feed conversion ratio and gross profit between the groups with 0.1%and 0.2%of wolfberry polysaccharide additive.The results showed that the use of wolfberry polysaccharide additive premixed feed has a positive effect on increasing the weight gain of fattening Tan sheep,reducing the feed conversion ratio,and improving the feed conversion efficiency.The addition of 0.1%and 0.2%of the wolfberry polysaccharide additive premixed feed had no significant differences.[Conclusions]The wolfberry polysaccharide additive has a positive effect on increasing the weight gain of fattening Tan sheep,reducing the feed conversion ratio,and improving the feed conversion efficiency.

Marine yeast Rhodotorula paludigena VA 242 a pigment enhancing feed additive for the Ornamental Fish Koi Carp

Skin colour is an important criterion in determining the aesthetic appeal of ornamental fishes,and thus their market worth.Hence the pigment enhancement in ornamental fishes has been the subject of extensive research by using various synthetic as well as natural pigment sources.Dietary composition is one of the most important elements that influence the development of pigmentation in fish.This study is an attempt to assess the possibility of using carotenogenic marine yeast as pigment enhancer in fish diet for Koi carp,Cyprinus carpio.The 60 days feeding experiment was done by using feed incorporated with mangrove associated marine yeast Rhodotorula paludigena VA242.Greater pigmentation in the scales of fishes fed with experimental feed was observed than that fed with the control diet(normal pellet feed).Furthermore the improved growth rate and general wellbeing in fishes fed with experimental feed provides scope for further studies in this field with respect to the growth and survival of fishes.

Overall assessment of antibiotic substitutes for pigs:a set of meta-analyses

Background:Antibiotic growth promoters are widely used to improve weight gain.However,the abuse of antibiotics can have many negative effects on people.Developing alternatives to antibiotics is an urgent need in livestock production.We aimed to perform a meta-analysis and network meta-analysis(NMA)to investigate the effects of feed additives as potential antibiotic substitutes(ASs)on bacteriostasis,growth performance,intestinal morphology and immunity.Furthermore,the primary,secondary,and tertiary ASs were defined by comparing their results with the results of antibiotics.Results:Among 16,309 identified studies,37 were summarized to study the bacteriostasis effects of feed additives,and 89 were included in the meta-analysis and NMA(10,228 pigs).We summarized 268 associations of 57 interventions with 32 bacteria.The order of bacteriostasis effects was as follows:antimicrobial peptides(AMPs)≈antibiotics>organic acids>plant extracts>oligosaccharides.We detected associations of 11 feed additives and 11 outcomes.Compared with a basal diet,plant extract,AMPs,probiotics,microelements,organic acids,bacteriophages,lysozyme,zymin,and oligosaccharides significantly improved growth performance(P<0.05);organic acids,probiotics,microelements,lysozyme,and AMPs remarkably increased the villus height:crypt depth ratio(V/C)(P<0.05);and plant extracts,zymin,microelements,probiotics,and organic acids notably improved immunity(P<0.05).The optimal AMP,bacteriophage,lysozyme,microelements,oligosaccharides,organic acids,plants,plant extracts,probiotics,and zymin doses were 0.100%,0.150%,0.012%,0.010%,0.050%,0.750%,0.20%,0.040%,0.180%,and 0.100%,respectively.Compared with antibiotics,all investigated feed additives exhibited no significant difference in effects on growth performance,IgG,and diarrhoea index/rate(P>0.05);AMPs and microelements significantly increased V/C(P<0.05);and zymin significantly improved lymphocyte levels(P<0.05).Furthermore,linear weighting sum models were used to comprehensively estimate the overall impact of each feed additive on pig growth and health.Conclusions:Our findings suggest that AMPs and plant extracts can be used as primary ASs for weaned piglets and growing pigs,respectively.Bacteriophages,zymin,plants,probiotics,oligosaccharides,lysozyme,and microelements can be regarded as secondary ASs.Nucleotides and organic acids can be considered as tertiary ASs.Future studies should further assess the alternative effects of combinational feed additives.

Effects of small peptides, probiotics, prebiotics, and synbiotics on growth performance, digestive enzymes, and oxidative stress in orange-spotted grouper, Epinephelus coioides, juveniles reared in artificial seawater

Aquaculture production efficiency may increase by using feed additives. This study investigated the effects of different dietary additives [w/w: 2% small peptides, 0.01% probiotics( Bacillus licheniformis) and 0.2% prebiotics(inulin)] on growth performance, digestive enzyme activities, and oxidative stress in juvenile Epinephelus coioides reared in artificial seawater of two salt concentrations(13.5 vs. 28.5). Weight gain rate was significantly higher in fish fed the diet supplemented with small peptides, B. licheniformis, inulin, or synbiotics than that in fish fed the basal diet; the greatest weight gain rate was found in fish fed the small peptide treatment [56.0% higher than basal diet]. Higher feed efficiency was detected in fish fed the diet supplemented with small peptides than that of fish in the other dietary treatments. Total protease activity in the stomach and intestines was highest in fish fed the small peptide-treated diet, whereas lipase activity was highest in those fed synbiotics(combination of Bacillus licheniformis and inulin) than that in fish fed the other treatments. Antioxidant enzyme(total superoxide dismutase and catalase) activities and hepatic malondialdehyde content were higher in fish receiving the dietary supplements and maintained in artificial seawater containing 13.5 salinity compared with those in the control(28.5). Hepatic catalase activity in grouper fed the diets with small peptides or synbiotics decreased significantly compared with that in control fish. Overall, the three types of additives improved growth rate of juvenile grouper and digestive enzymes activities to varying degrees but did not effectively improve antioxidant capacity under low-salinity stress conditions.