Effects of feeding untreated, pasteurized and acidified waste milk and bunk tank milk on the performance, serum metabolic profiles, immunity, and intestinal development in Holstein calves

Background: The present experiment was performed to assess the effects of different sources of milk on the growth performance, serum metabolism, immunity, and intestinal development of calves. Eighty-four Holstein male neonatal calves were assigned to one of the following four treatment groups: those that received bunk tank milk(BTM), untreated waste milk(UWM), pasteurized waste milk(PWM), and acidified waste milk(AWM) for 21 d.Results: Calves in the BTM and AWM groups consumed more starter(P < 0.05) than those in the UWM group.Average daily gain in the UWM group was the highest(P < 0.05). Calves exhibited the highest(P < 0.05) serum total protein, albumin, total cholesterol, high density lipoprotein, triglycerides, growth hormone, immunoglobulin(Ig) A and Ig M concentrations in the UWM group, highest malondialdehyde and tumor necrosis factor-α in the PWM group(P < 0.05), and highest glutathione peroxidase and Ig G in the BTM group(P < 0.05). The jejunum and ileum of the calves in all treatments presented a slight inflammatory response. The jejunal inflammation scores were higher(P < 0.05) in the UWM and AWM groups than the BTM group; the ileal inflammation scores increased more(P < 0.05) in the AWM group than the BTM group. Jejunal immunohistochemical scores(IHS) were higher(P < 0.05) in the PWM and AWM groups than the BTM group. Compared to the other three groups, calves feeding on BTM had lower(P < 0.05) ileal IHS. Jejunal interleukin(IL)-1β, IL-8, and IL-10 mRNA expression in the UWM group was the highest(P < 0.05). Calves fed AWM increased(P < 0.05) mRNA expression of IL-8 and toll like receptor 4(TLR-4) in the jejunum and IL-8, IL-1β, IL-6, IL-8, and IL-10 in the mesenteric lymph nodes.Conclusions: Overall, bunk tank milk is the best choice for calf raising compared to waste milk. The efficiency of feeding pasteurized and acidified waste milk are comparable, and the acidification of waste milk is an acceptable labor-saving and diarrhea-preventing feed for young calves.

Kinetic and thermodynamic studies of the esterification of acidified oil catalyzed by sulfonated cation exchange resin

This study describes the kinetics and thermodynamics of the esterification of acidified oil with methanol catalyzed by sulfonated cation exchange resins（SCER）. The effects of the mass ratio of methanol to acidified oil,reaction temperature,and catalyst loading were studied to optimize the conditions for maximum conversion of free fatty acids（FFAs）. The results showed that the optimal conversion rate of FFAs was 91.87% at the mass ratio of methanol to acidified oil of 2.5：1.0,reaction temperature of 65.0 °C,catalyst loading of 5.0 g and reaction time of 8.0 h. The external and internal mass transfer resistances were negligible based on the experimental results and a pseudo-homogeneous kinetic model was proposed for the esterification. The activation energy and thermodynamic parameters including G,S and H were determined. The conversion rates of FFAs obtained from the established model were in good agreement with the experimental data.

Temperature and Acidified Solvent Effect on Total Anthocyanins and RP-HPLC Phenolic Acids Determination in Selected Spices

Total anthocyanins of spices (Syzygium aromaticum L., Coriadrum sativum L., Cuminum cyminum L., Zingiber officinale Rosc., Elettaria cardamomum, Curcuma longa, Rhus coriaria L., Cinnamomum zeylanicum Blume, Foeniculum vulgare Mill and Laurus nobilis L.) were determined using acidified (1% HCl) solvents (methanol, ethanol and acetone) at three temperatures (20℃, 40℃ and 60℃). Also phenolic acids were separated and identified by RP-HPLC. Results showed that sumac and cinnamon had the highest levels of anthocyanins, while for the acetone the cinnamon indicated the highest amount of anthocyanins when methanol and ethanol were used as extracting solvents at 20℃. At 40℃ using ethanol, sumac showed the highest level of anthocyanins whereas acetone solvent yielded the highest anthocyanin contents for cinnamon. At 60℃, cinnamon showed the highest level of anthocyanins when methanol and acetone were the solvents, while sumac had the highest anthocyanins level using ethanol as solvent. HPLC results showed ten phenolic acids found in those spices and varied in their concentrations. Gallic acid had the highest level (1642.3 mg/100g) (cloves). Gentisic acid had the lowest level (1.2 mg/100g) in ginger. Also sumac showed the highest level of chlorogenic acid (1528.7 mg/100g). Some acids were not found in some spices, for instance, benzoic acid was not found in coriander, cumin, ginger, green cardamom, cinnamon and sweet laurel.

Antimicrobial Activity of Acidified Sodium Chlorite and Cell Free Culture Supernatent of Lactic Acid Bacteria against <i>Salmonella</i>Typhimurium

Most methods used by food industries to decontaminate eggs involve washing of egg surface with various chemicals. In this study, the effectiveness of two organic decontaminants viz., acidified sodium chlorite (ASC) and cell free culture supernatant (CFCS) of two lactic acid bacteria (Lactobacillus plantarum and Pediococcus cerevisiae) was evaluated for the decontamination of spiked Salmonella Typhimurium on chicken egg shell surface. Acidified sodium chlorite at 100 μl/L concentration with the contact time of 20 min completely inhibited S. Typhimurium on egg shell surface while at 50 μl/L concentration 1 - 2 log10 units reduction was observed in counts of S. Typhimurium as compared to control group. Likewise, CFCS of P. cerevisiae completely inhibited the growth of S. Typhimurium on 30 min contact, whereas L. plantarum and combination of both were revealed significant reduction in the counts of S. Typhimurium counts.

Response of antioxidant defense system in copepod Calanus sinicus Brodsky exposed to CO_2-acidified seawater

Marine zooplankton responds sensitively to elevated seawater CO_2 concentration. However, the underlying physiological mechanisms have not been studied well. We therefore investigated the effects of elevated CO_2concentration（0.08%, 0.20%, 0.50% and 1.00%） on antioxidant defense components, as well as two detoxification enzymes of Calanus sinicus（copepod）. The results showed that glutathione peroxidase（GPx） activity exposed to CO_2-acidified seawater was significantly stimulated while other antioxidant components, including glutathione-Stransferase（GST） activity, superoxide dismutase（SOD） activity decreased significantly with reduced glutathione（GSH） level and GSH/oxidized glutathione（GSSG） value. CO_2-acidified seawater exhibited stimulatory effects on adenosine triphosphatase（ATPase） activity and acetylcholinesterase（Ach E） activity was inhibited. Moreover, the results of principal component analysis indicated that 75.93% of the overall variance was explained by the first two principal components. The elevated CO_2 concentration may affect the metabolism and survivals of copepods through impacts these enzymes activities. Further studies are needed to focus on the synergistic effects of elevated CO_2 concentration and other environmental factors on copepods.

Mechanisms of action of leptin in preventing gastric ulcer

To investigate the effects of leptin （1-20μg/kg） on acidified ethanol （AE）- and indomethacin （Indo）-induced gastric lesions in rats and compare it with ranitidine, lansoprazole, and omeprazole and to determine its mechanisms of actions.METHODS： Gastric ulcers, which were approximately 1 mm in width, formed in the glandular portion of the gastric mucosa produced by oral administration of either AE or Indo were taken as ulcer index. The inhibitory effect of subcutaneous administration of leptin, two proton pump inhibitors （PPIs） lansoprazole and omeprazole, or H2-receptor antagonist ranitidine 30 min before AE or Indo was evaluated.A radioimmunoassay was used to determine the PGE2 concentration in the homogenate of the glandular portion of the stomach. We performed histological study of the glandular stomach for the evaluation of total, acidic, and sulfated mucus content.RESULTS： Subcutaneous administration of leptin, two PPI slansoprazole and omeprazole or H2-receptor antagonist ranitidine 30 min before AE or Indo produced a dosedependent and reproducible inhibition of gastric ulcers （GUs）. This inhibition was found to be more potent than other antagonists used. In N^G-nitro L-arginine methyl ester （L-NAME）-pretreated animals, the ulcer prevention ability of leptin in AE-induced ulcer was significantly reduced,compared to rats without L-NAME pretreatment. However,the ulcer prevention ability of leptin was not altered by L-NAME treatment in Indo-induced ulcers. Leptin produced a dose-dependent increase in PGE2 level in the gastric glandular tissues. Leptin also increased mucus secretion.CONCLUSION： The results of the present study show that leptin inhibits GU formation by AE or Indo in a dosedependent and reproducible manner in rats. The results also suggest that leptin prevents ulcer formation by increasing the activities of the cyclo-oxygenase and/or nitric oxide pathways and by increasing mucus secretion.

Effects of Microencapsulated Compound Acidifier on Acidity and Development of Gastrointestinal Tract in Weaning Piglets

The effects of different types of compound acidifiers （encapsulated and non-encapsulated） in maize-soybean basic diets on acidity and development of the gastrointestinal tract in weaning piglets were investigated in this study. 64 28-day-old weaned Landrace x Yorkshire hybrid piglets with average weight of （7.00 ±0.10） kg were selected and grouped into four treatments with four pigs （ half boars and half sows） in each repeat of four repeats in each treatment based on single-factor test design principles, and the pre-test period was 3 days but the test period was 35 days. The results showed that compared with acid-free diet group, encapsulated compound acidifier could reduce pH of stomach and intestinal in weaning piglets significantly （P 〈 0.01 ）, while Test group 1 could also increase the relative weight of stomach and intestinal in piglets significantly （P 〈 0.05 ）. Compared with non-encapsulated acidifier, encapsulated compound acidifier could greatly decrease pH in jejunum and ileum of weaning piglets （ P 〈 0.05） or relative weight of stomach in piglets （ P〈0.05）, while Test group 1 could also enhance the relative weight of intestinal in piglets significantly （ P 〈0.01 ）. In addition, encapsulated compound acidifiers significantly increased the ratio between the villus height and crypt depth of jejunum （ P 〈0.01 ）. Accordingly, the microencapsulated compound acidifier in diets of weaning piglets can promote the development of gastrointestinal tracts for piglets by reducing pH of gastrointestinal tracts.

Impact of ocean acidification on physiology and microbiota in hepatopancreas of Pacific oyster Crassostrea gigas

The hepatopancreas is an important tissue involved in various biological metabolism for mollusks,but its responses to ocean acidifi cation(OA)have not been well evaluated.In this study,the oysters were cultured in simulated conditions by continuously bubbling with ambient air(pH=8.10)or air-CO_(2)(pH=7.50)for up to two months,and the variations on the antioxidant capacity,digestive ability,and microbiota composition in hepatopancreas of Crassostrea gigas were analyzed.The results show that although superoxide dismutase and glutathione responded quickly to OA stress,the antioxidant capacity of the hepatopancreas was inhibited,as revealed by the decrease of the total antioxidant capacity,which led to an upward trend of the malondialdehyde,demonstrating that the oxidative damages were accumulated under the OA process.The determination of the digestive ability manifested as the decrease of pepsin activity and the recovery of lipase and amylase activity after long-term acidifi cation,which may be helpful to improve the adaptability of oysters.In addition,analysis on 16S rDNA amplicon revealed that the total species abundance and diversity of the hepatopancreas microbiota experienced a dynamic change,but fi nally it decreased greatly after long-term acidifi cation.The structure of the hepatopancreas microbiota was changed drastically with the change of the dominant species from aerobic to the anaerobic and facultative anaerobic bacteria,and the abnormal proliferation of some species,such as genus of Mycoplasma and order Clostridiales,which may aggravate the adverse eff ects of OA on the physiological functions of the hepatopancreas.As a result,our fi ndings enrich our understanding of the accumulated oxidative damage and adaptive digestive ability in oyster hepatopancreas caused by OA.For the fi rst time,the changes of the hepatopancreas microbiota under long-term acidifi cation conditions are described,proving a good reference for the study of the response and adaptation mechanisms of bivalve mollusks in a wide range of oceans OA.

Effect of natural and anthropogenic acidifi cation on aluminium distribution in forest soils of two regions in the Czech Republic

To elucidate the dynamics of aluminium(Al),an element potentially toxic and strongly aff ected by acidifi cation processes,in soils,we selected two regions that were similar in relief,soil types,and vegetation cover but diff ered markedly in their history of acid precipitation:the JizerskéMountains(anthropogenically acidifi ed)and the NovohradskéMountains(naturally acidifi ed)in the Czech Republic.The levels of Al forms(exchangeable and organically bound)associated with diff erent environmental impacts were measured and univalent,divalent and trivalent Al species were quantifi ed using HPLC/IC.Exchangeable and organically bound Al concentrations were higher in the anthropogenically acidifi ed area.Only the concentrations of the leastdangerous species,the univalent,in organic soil horizons were similar for both mountains.The concentrations of exchangeable Al forms were correlated with Ca concentrations and with pH in the organic horizon.The known relationship of Al with soil pH was stronger in the mineral horizons.Relationships of exchangeable Al forms concentrations with sulphur concentrations or even more with the sulphur calcium molar ratio were found only in the JizerskéMountains,not in the Novohradské.Generally,the obtained results support the hypothesis that mechanisms diff ered between natural and anthropogenic acidifi cation.

Effects of Compound Acidifier and Probiotics on Production Performance,Blood Biochemical Indexes,Antioxidant Indexes and Salmonella Infection of Laying Hens

This study evaluated the effects of compound acidifier and probiotics on production performance, blood biochemical indexes, antioxidant indexes and Salmonella infection of laying hens. A total of 600 50-week-old healthy laying hens with similar laying rate were randomly assigned to four groups, 10 repeats each group, and each repeat contained 15 chickens. The laying hens in control group were fed a basal diet, and in the other three experimental groups were fed basal di- ets supplemented with 300 g/t probiotics, 0. 1% compound acidifier in the drinking water every other day, and 300 g/t probiotics ＋ 0.1% compound aeidifier in the drinking water every other day, respectively. After the feeding of 16 weeks, a total of 60 laying hens from control group were divided into four treatments as the same above for a 13-day long Salmonella challenge （1.3×10^8 CFU） trial. The results were shown as follows： no significant effects were observed on production performance, hemoglobin content, the superoxide dismutase activity and total antioxidant capacity of reproductive organ in compound acidifier and probiotics groups （ P 〉 0.05 ）. Dirty egg rate was significantly decreased in compound acidifier group, probiotics group and combination group of both （P 〈 0.05 ）. Compared with the control group, white blood cell count in probiotics group was significantly decreased （P 〈0.05 ）, and the immunoglobulin content in probiotics group tended to be increased （P = 0.061 ）. The malondialdehyde （MDA） content in oviduct isthmus of hens in compound acidifier group and combination group was significantly decreased compared with the control group （ P 〈 0.05 ）. The Salmonella positive rate in oviduct of hens in compound acidifier group was significantly decreased at the 7th and 14^th days （ P 〈0.05 ）, but that in probiotics group and combination group was not significantly different compared with control group （ P 〉 0.05 ）. In conclusion, compound acidifier and probiotics can improve health status of laying hens through decreasing the dirty egg rate and increasing antioxidant capacity and immunity of them, thus reducing Salmonella infection of body and eggs.

Effects of Dietary Mannan Oligosaccharides and Calcium Formate on Performance and Egg Quality of Japanese Quail （Coturnixjaponica）

The aim of this experiment was to study the effects of dietary supplementation of mannan oligosaccharides （MOS）, extracted from yeast Saccharomyces cerevisiae and acidifier calcium formate （CF） on some performance parameters and egg quality characteristics of Japanese quail （Coturnixjaponica）. During the experimental period, which lasted 90 days, one hundred eighty three, 42-day-old quail, were distributed into 4 groups of 3 replications each and were placed in separate wire suspended cages. The birds of control group received a commercial feed, while the birds of the other 3 groups received the same feed, to which either 6 g CF kg^-1 or 1 g MOS kg^-1 or both 6 g CF kg^-1 plus 1 g MOS kg^-1 were added. The live weight, feed consumption, feed conversion ratio and mortality of birds were not significantly affected. The addition of MOS in the feed significantly （P 〈 0.05） increased palmitic acid percentage of egg yolk. Also, the addition of CF significantly （P 〈 0.05） decreased egg shape index and palmitic acid percentage of egg yolk. Furthermore, significant （P 〈 0.05） interaction between MOS and CF was observed on palmitic acid percentage, egg shape index and egg shell thickness. No significant effect was observed for egg： weight, specific weight, parts percentage （yolk, albumen, shell）, shell deformation, yolk diameter and yolk colour （L＊a＊b＊ colour space）.

Milk Replacer Acidification for Free-Access Feeding: Effects on the Performance and Health of Veal Calves

Objectives of this study were to investigate the effects of milk replacer (MR) acidification for free- access feeding on pre- and post-weaning performance, morbidity and mortality of calves. Calves were randomly assigned to free-access feeding of acidified (ACID, n = 31) or non-acidified (NON, n = 31) MR, and weaned at 42 days. ACIDMR was prepared to pH 4.0 - 4.5 using formic acid. Intakes were measured daily and weights weekly. Samples of ACID and NON MR were analyzed for coliform and aerobic bacterial growth. After weaning, calves transitioned to a grain-fed veal diet, weighed every 2 weeks. At slaughter (approximately 6 months of age), lungs were evaluated for gross pathological changes and dressed carcass weights were obtained. Generalized linear mixed models were constructed to examine the effects of MR acidification. Differences by treatment group for pre- and post-weaning morbidity and mortality were tested using Pearson’s χ2 and Fisher’s exact tests. ACID calves consumed less MR than NON (10.6 vs. 11.7 L/d, P = 0.02). Acidification tended to promote earlier onset of starter ration consumption (32.0 vs. 39.5 d, hazard ratio = 1.5, P = 0.07), but did not affect average daily starter ration or water intakes across the pre-weaning period. ACID and NON calves did not differ for BW at weaning, pre- or post-weaning ADG or dressed carcass weight. ACID MR had less coliform (P < 0.001) and aerobic bacterial growth (P < 0.001) than NON MR, but odds of disease treatment and mortality did not differ. ACID calves tended to have lower odds of pulmonary lesions during post-mortem inspection than NON calves (OR = 0.3, P = 0.07). These results indicate that under free-access feeding conditions, acidification limited bacterial growth and MR intake, but there were no long-term impacts of acidification on calf performance or health. In conclusion, acidification to pH 4.0 - 4.5 will significantly reduce bacterial growth in milk fed to calves.

Effects of ocean acidifi cation driven by elevated CO_2 on larval shell growth and abnormal rates of the venerid clam, Mactra veneriformis

A bstract The venerid clam(M actra veneriformis Reeve 1854) is one of the main cultured bivalve species in intertidal and shallow subtidal ecosystems along the west coast of Korea. To understand the effects of ocean acidifi cation on the early life stages of Korean clams, we investigated shell growth and abnormality rates and types in the D-shaped, umbonate veliger, and pediveliger stages of the venerid clam M. veneriformis during exposure to elevated seawater pCO_2. In particular, we examined abnormal types of larval shell morphology categorized as shell deformations, shell distortions, and shell fi ssures. Specimens were incubated in seawater equilibrated with bubbled CO_2-enriched air at(400±25)×10^(-6)(ambient control),(800±25)×10^(-6)(high pCO_2), or(1 200±28)×10^(-6)(extremely high pCO_2), the atmospheric CO_2 concentrations predicted for the years 2014, 2084, and 2154(70-year intervals; two human generations), respectively, in the Representative Concentration Pathway(RCP) 8.5 scenario. The mean shell lengths of larvae were signifi cantly decreased in the high and extremely high pCO_2 groups compared with the ambient control groups. Furthermore, under high and extremely high pCO_2 conditions, the cultures exhibited signifi cantly increased abundances of abnormal larvae and increased severity of abnormalities compared with the ambient control. In the umbonate veliger stage of the experimental larvae, the most common abnormalities were shell deformations, distortions, and fi ssures; on the other hand, convex hinges and mantle protuberances were absent. These results suggest that elevated CO_2 exerts an additional burden on the health of M. veneriformis larvae by impairing early development.

Effects of low pH on zooplankton in some suburban waterbodies of Chongqing City

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Effects of alkaline ameliorator additions on the acidic buffering abilities of aluminum－rich alfisols

Lime and coal flying ash applications could mitigate pollution from acid deposition and improve the buffering ability of two acidic soils sampled from Zhejiang Province. The results showed that soil alkalinity and acidified buffering capacities (QpHs ) were significantly increased, especially for liming treatment; whereas, the amounts of SO24- adsorbed by treated soils were decreased to some degrees because net negative charges of soil oxide colloidal surfaces were increased with the decrease in soil acidity, although the soil fixation abilities for adsorbed SO24- were not reduced. These facts indicated that after the alkaline ameliorators were applied, the positive and adverse effects resulted from sulfate-type acid deposition were simultaneously existed in these soil treatments.

Prospective Alternatives of Antibiotics in Animal Diet

Antibiotics have been used in animal feeding for long history.In recent years,much attention has been received for their negative effects on animal and human being as well.Technology has been focused on alternatives of antibotics,such as probiotics,oligosaccharides,acidifiers,Chinese herds,chemical drugs,and other environmental measures.Their mechanism,effects,related factors and their prospect in the future were discussed in this paper.

Effects of Supplementary Acidifiers on Lambs

[ Objective] To provide a reference for understand effects of acidifiers on digestibility of lambs. [Method] Feeding experiment as well as digestion and metabolism experiment was conducted to evaluate effects of supplementing acidifiers on ultra-early weaned lambs. [ Result] Diets of ultra-early weaned lambs supplemented with acidifiers greatly improved their production performance and increased digestibility of feed. However, different acidifier products had certainly various effects on lambs. Acidifier product I increased weight gain, feed conversion ratio and apparent di- gestibility of main nutrients more greatly than acidifier product II did, while the result was contrary in reducing diarrhea incidence. [ Conclusion] Whether the acidifiers can increase digestibility of nutrients or not is still uncertain and needs further studies.

Prevalence of Antibiotic Resistant Bacteria on Tomato Surfaces and Effectiveness of Disinfectants in Reducing the Microbial Load

This study was conducted to isolate and identify antibiotic resistant bacteria in fresh tomato sold in three different local markets of Dhaka city. On an average 〉 5.0 log CFU/g of natural microbial populations and coliform bacteria was present in the samples. Prevalence of Salmonella spp., E. coli, Listeria spp., and Yersinia spp., were recorded through cultivation dependent assay of tomato samples of different markets. Almost all of the isolates were uniformly resistant to rifampicin, erythromycin, clindamycin and oxacillin （100%）, vancomycin （93%）, amoxicillin （87%）, whereas 60% of the isolates were found to be resistant to ampicillin and cephalexin. Antibiotic sensitivity test of the presumptive E. coli and Salmonella spp. and corresponding plasmid profiling indicated a correlation of plasmid mediated multidrug resistance （MDR） of these environmental bacteria. Washing with sanitizing agents such as acidified sodium chlorite （ASC） and 200 ppm chlorinated water was able to reduce _〈 2.0 log CFU/g of natural microflora and coliform bacteria. In contrast, ASC was able to reduce 〈 2.0 log CFU/g of other food borne pathogens and, chlorinated water was able to reduce up to undetectable level. Therefore, washing of tomato with 200 ppm chlorinated water could be useful in reducing the pathogen populations on tomatoes.

Comparative Evaluation of Mannan Oligosaccharides and Acidifier Calcium Formate on the Quail Digestive Tract

Three hundred, one-day-old Japanese quail （Coturnixjaponica） divided into four groups, with three subgroups each, were fed a basal diet that served as control, or a basal diet containing 6 g calcium formate （CF）/kg or 2 g mannan oligosaccharides （MOS）/kg or both 6 g CF/kg plus 2 g MOS/kg. On 21st and 42nd days the pH of the quail crop, proventriculus, gizzard, duodenum, jejunum, ileum, large intestine and ceca were measured in situ and the total aerobic bacteria, lactic acid bacteria, Enterobacteriaceae and coliforms counts of the cecal content were recorded. Results showed that MOS decreased the cecal pH on the 42nd day and the total aerobic bacteria counts on 21st day. Moreover, CF decreased the cecal pH on the 42nd day and the lactic acid bacteria counts on 21st day. Interaction between MOS and CF was noticed on the cecal pH on the 42nd day, as the combined dietary addition of MOS and CF resulted in lower pH, compared to each separate addition. Also, interaction was noticed on the cecal bacterial counts on the 21st day, as the combined dietary addition of MOS and CF resulted in lower total aerobic bacteria, Enterobacteriacea and coliform counts, compared to each separate addition.

Effects of Compound Acidifier on Growth Performance and Serum Biochemical Parameters of Heat-stressed Wenchang Chickens

[Objective]The paper was to investigate the effects of compound acidifier on growth performance and serum biochemical parameters of heat-stressed Wenchang chickens.[Method]A total of 28881-day-old Wenchang chickens with the same genetic background and similar initial weight(985.63±20.35 g)were randomly divided into four groups,four replicates per group and 18 chickens per replicate.Birds were fed the basal diet supplemented with 0 g/kg(control group),1 g/kg(groupⅠ),2 g/kg(groupⅡ)and 3 g/kg(groupⅢ)compound acidifier.The trial lasted 35 d.[Result]The daily gain of experimental groupⅠwas significantly higher than those of control group and groupⅢ(P<0.05),and the feed intake of experimental groupⅠwas also markedly higher than that of control group(P<0.05),but the feed gain ratio of experimental groupⅠwas significantly lower than that of groupⅢ(P<0.05).Compared with control group,the serum total protein and albumin levels of experimental groupⅠincreased(P>0.05),but the serum uric acid concentration decreased(P>0.05).[Conclusion]Supplementing 1 g/kg compound acidifier could improve the growth performance of heat-stressed Wenchang chickens.