The effect of Epigallocatechin‐3‐gallate on small intestinal morphology,antioxidant capacity and anti‐inflammatory effect in heat‐stressed broilers

This study was to investigate the effects of Epigallocatechin‐3‐gallate (EGCG) on intestinal morphology, antioxidant capacity and anti‐inflammatory response in heat‐stressed broiler. A total of 192 2‐week‐old Arbour Acres broilers chickens were divided into four groups with six replicates per group and eight chickens per replicate: one thermoneutral control group (28°C, group TN), which was fed the basal diet; and three cyclic high‐temperature groups (35°C from 7:00 to 19:00 hr; 28°C from 19:00 hr to 7:00 hr, heat stress group), which were fed the basal diet supplementation with EGCG 0 mg/kg (group HS0), 300 mg/kg (group HS300) and 600 mg/kg (group HS600). The gut morphology and intestinal mucosal oxidative stress indicators, as well as intestinal barrier‐related gene expression, were analysed. The results showed that compared with group TN, heat stress reduced the villus height (VH), activities of glutathione peroxidase (GSH‐Px), superoxide dismutase (SOD)and catalase (CAT), increased the crypt depth (CD) and malondialdehyde (MDA)content at 21, 28 and 35 days (p < 0.05). After the heat‐stressed broilers were supplemented with EGCG, VH, VH/CD (V/C), and the activities of GSH‐Px, SOD and CAT were increased, and CD and MDA content were reduced compared with those in group HS0 without EGCG supplementation at 21, 28 and 35 days (p < 0.05). The EGCG supplementation promoted the gene expression of nuclear factor‐erythroid 2‐related factor 2 (Nrf2), Claudin‐1, Mucin 2 (Muc2) and alleviated the nuclear factor‐kappa B (NF‐κB) and lipopolysaccharide‐induced tumour necrosis factor (LITAF) gene expression compared with group HS0 (p < 0.05). Moreover, intestinal morphology was strongly correlated with antioxidant ability and inflammatory response. In conclusion, EGCG alleviated the gut oxidative injury of heat‐stressed broilers by enhancing antioxidant capacity and inhibiting inflammatory response.     

Dietary supplementation with glutamine and γ‐aminobutyric acid improves growth performance and serum parameters in 22‐ to 35‐day‐old broilers exposed to hot environment

This study was designed using 360 21‐day‐old chicks to determine the influences of diet supplementation with glutamine (5 g/kg), γ‐aminobutyric acid (GABA, 100 mg/kg) or their combinations on performance and serum parameters exposed to cycling high temperatures. From 22 to 35 days, the experimental groups (2 × 2) were subjected to circular heat stress by exposing them to 30–34 °C cycling, while the positive control group was exposed to 23 °C constant. The blood of broilers was collected to detect serum parameters on days 28 and 35. Compared with the positive control group, the cycling high temperature decreased (p < 0.05) the feed consumption, weight gain and serum total protein (TP), glucose, thyroxine (T4), insulin, alkaline phosphatase (ALP), glutamine, GABA and glutamate levels, while increased (p < 0.05) the serum triglyceride (TG), corticosterone (CS), glucagon (GN), creatine kinase (CK), glutamic oxaloacetic transaminase (GOT), nitric oxide synthase (NOS), glutamate pyruvate transaminase (GPT) and lactate dehydrogenase (LDH) levels during 22–35 days. However, dietary glutamine (5 g/kg) increased (p < 0.05) the feed consumption, weight gain and serum levels of glutamine, TP, insulin and ALP, but decreased (p < 0.05) the serum TG, CK, GOT, NOS and GPT levels. Diet supplemented with GABA also increased (p < 0.05) weight gain and the serum levels of TP, T4, ALP, GABA and glutamine. In addition, the significant interactions (p < 0.05) between glutamine and GABA were found in the feed consumption, weight gain and the serum ALP, CK, LDH, GABA, T3 and T4 levels of heat‐stressed chickens. This research indicated that dietary glutamine and GABA improved the antistress ability in performance and serum parameters of broilers under hot environment.     

Effects of different dl‐selenomethionine and sodium selenite levels on growth performance,immune functions and serum thyroid hormones concentrations in broilers

This trial was conducted in a 2 × 3 + 1 factorial arrangement based on a completely randomized design to evaluate the effects of different dl ‐selenomethionine (dl ‐Se‐Met) and sodium selenite (SS) levels on growth performance, immune functions and serum thyroid hormones concentrations in broilers. A total of 840 Ross 308 broilers (7 days old) were allocated by body weight to seven treatments (three replicates of 40 birds each treatment) including (1) basal diet (containing 0.04 mg of selenium (Se)/kg; control) without supplementary Se; (2, 3 and 4) basal diet + 0.05, 0.15 or 0.25 mg/kg Se as SS; (5, 6 and 7) basal diet + 0.05, 0.15 or 0.25 mg/kg Se as dl ‐Se‐Met. The experiment lasted 42 days. The results revealed that dietary Se supplementation improved (p < 0.05) average daily gain, feed efficiency, immune organ index, serum immunoglobulin A (IgA), immunoglobulin G (IgG), immunoglobulin M (IgM) and triiodothyronine (T₃) concentrations and decreased (p < 0.01) thyroxine (T₄)/T₃ ratio in serum compared with the control. Broilers receiving the dl ‐Se‐Met‐supplemented diets had higher (p < 0.05) feed efficiency, thymus index, the amounts of IgA, IgG, IgM and T₃ as well as lower (p < 0.05) serum T₄ concentrations and T₄/T₃ ratio than those consuming the SS‐supplemented diets. Serum IgA and IgM levels of broilers fed 0.15 mg Se/kg were significantly higher (p < 0.05) than those of broilers fed 0.05 or 0.25 mg Se/kg. In summary, we concluded that dl ‐Se‐Met is more effective than SS in increasing immunity and promoting conversion of T₄ to T₃, thus providing an effective way to improve the growth performance of broilers. Besides, based on a consideration of all experiment indices, 0.15 mg Se/kg was suggested to be the optimal level of Se supplementation under the conditions of this study.     

Effects of dietary supplementation of synbiotics on growth performance,intestinal morphology,sIgA content and antioxidant capacities of broilers

Today, several strategies are being used to decrease the serious effects of antibiotics abuse on broilers industry and public health, among which synbiotics are one of the most promising antibiotic alternative. This study was undertaken to assess the effects of synbiotics, which composed of probiotics (Bacillus subtilis) and prebiotics (xylooligosaccharide and mannanoligosaccharide), on growth performance, intestinal morphology, sIgA content and antioxidant parameters of broilers. Four hundred and fifty one‐day‐old commercial Cobb48 broilers were assigned to five treatments consisting of six replicates of 15 birds each pen. Five dietary treatments include basal diets (control), basal diets plus antibiotics (4 mg/kg Xanthomycin), basal diets plus 1 g of probiotics B. subtilis product/kg of diets (4 × 10⁸ cfu/kg), basal diets plus 150 mg/kg xylooligosaccharide (35%) and 1 g/kg mannanoligosaccharide (75%), and basal diets plus synbiotics (1 g of probiotics B. subtilis product/kg of diets (4 × 10⁸ cfu/kg), 150 mg/kg xylooligosaccharide (35%) and 1 g/kg mannanoligosaccharide (75%). The results demonstrated that on 21 and 42 days, dietary supplementation of the synbiotics significantly increased daily weight gain (p < 0.05), feed efficiency (p < 0.05), the villus height and villus:crypt ratio in the duodenum, jejunum and ileum (p < 0.05), as well as intestinal mucosa sIgA content (p < 0.05), serum T‐SOD activity (p < 0.05) and lysozyme content (p < 0.05), comparing with control group. In conclusion, synbiotics (B. subtilis and xylooligosaccharide and mannanoligosaccharide) is one of the safe and ideal dietary supplementations to increase broilers' growth performance by improving small intestinal morphology, sIgA content and antioxidant capabilities.     

Improving effects of dietary rumen protected γ‐aminobutyric acid additive on apparent nutrient digestibility,growth performance and health status in heat‐stressed beef cattle

This study was aimed to investigate the effects of rumen‐protected γ‐aminobutyric acid (RP‐GABA) on apparent nutrient digestibility, growth performance and health status in heat stressed beef cattle. Fifty Jinjiang Yellow cattle were randomly assigned to 5 treatments (10 animals/treatment). Treatments 1 to 5 were basal diets affixed with 0 (control), 8, 16, 24 and 32 mg of RP‐GABA/kg of body weight (BW) respectively. The trial lasted 45 days. Apparent digestibility of crude protein (CP), crude fiber (CF) and calcium (Ca) quadratically increased with increasing RP‐GABA (p < .01), while apparent digestibility of phosphorus (P) tended to quadratically increase (p = .09). Dietary supplementation with increasing RP‐GABA linearly increased DM digestibility and average daily gain (ADG) (p < .01), whereas the feed to gain (F:G) ratio linearly decreased with increasing RP‐GABA (p < .01). The average daily feed intake (ADFI) value tended to linearly increase with RP‐GABA supplementation (p = .08). Total protein (TP), blood urea nitrogen (BUN) and malondialdehyde (MDA) levels quadratically decreased (p < .01) with increasing RP‐GABA, however albumin (ALB), glucose (GLU), superoxide dismutase (SOD), triiodothyronine (T3) and thyroxine (T4) levels quadratically increased (p ≤ .01). In conclusion, the present results indicated that dietary supplementation with RP‐GABA led to improved nutrient digestibility, growth performance and antioxidant status in heat stressed beef cattle.     

Effects of Astragalus membranaceus on growth performance,carcass characteristics,and antioxidant status of broiler chickens

Abstract

An experiment was conducted using 720 one-day-old Arbor Acres broiler chickens to evaluate the effects of Astragalus membranaceus root powder (AMP), Astragalus polysaccharides (APS) on growth performance, carcass characteristics, and antioxidant enzymes, and metabolites of blood and liver in broiler chickens. The six dietary treatments included a control that was a corn–soybean meal basal diet; basal diet supplemented with 120 mg/kg antibiotic; 350 mg/kg APS; or 5000, 10,000, or 15,000 mg/kg diet of AMP. Supplementation of 10,000 mg/kg AMP increased average daily gain and feed conversion rate of broilers in grower period (22–42 d) and over the entire experiment compared to basic diet. Responses of antioxidant status to dietary APS and AMP varied depending on the age of the broilers. Beneficial effects of AMP on growth and feed utilization of broilers could be obtained by inclusion of AMP at the rate of 10,000 mg/kg diet.     

Effects of calcium soap of rice bran oil fatty acids supplementation alone and with DL‐α‐tocopherol acetate in lamb diets on performance,digestibility, ruminal parameters and meat quality

Thirty‐six Malpura lambs (28 day old and 6.7 ± 0.25 kg BW) were distributed equally in three groups having six males and six female. They were ad libitum fed individually three different experimental diets containing calcium soap of fatty acids (CA‐FA) at 0 (T₁) and 40 (T₂ and T₃) g/kg concentrate up to six months of age. Animals in T₃ were supplemented additionally with 40 mg DL‐α‐tocopherol acetate/kg of concentrate. The roughage moiety included ad libitum dry Prosopis cineraria and fresh Azadirachata indica leaves. All the lambs were allowed to suckle from their dam up to weaning (90 day of age). Supplementation of Ca‐FA improved weight gain and feed conversion ratio during both pre‐ (28–90 days) and post‐weaning (91–180 days) phases; however, no effect of DL‐α‐tocopherol was observed. Metabolic parameters during post‐weaning phase revealed non‐significant effect on digestibility but improved nitrogen balance in the test groups. The effect on biochemical attributes did not show any significant alteration in ruminal parameters, blood biochemicals and urinary purine derivatives. Carcass traits revealed higher (p < 0.05) dressing yield and loin eye area with Ca‐FA supplementation. The value of thiobarbituric reactive substances for nuggets prepared from frozen carcasses revealed significant (p < 0.05) reduction in T₃ compared to the other dietary groups. Fatty acid profile of adipose tissue revealed higher (p < 0.001) 9‐octadecanoic, 9‐12‐octadecadienoic, polyunsaturated fatty acids (PUFA), higher ratio of PUFA/saturated fatty acids (SFA), ω‐6/ω‐3 and lower SFA in Ca‐FA‐supplemented groups. It is concluded that supplementation of 40 g/kg calcium soap prepared from industrial grade rice bran oil in lamb ration provided additional energy intake, improved N utilization, gain and feed conversion ratio besides improving dressing yield and meat quality with CLA enriched fatty acid profile. DL‐α‐tocopherol acetate when supplemented at 40 mg/kg feed reduced lipid oxidation of meat products thus improving its keeping quality.     

Effect of resveratrol on growth performance,rectal temperature and serum parameters of yellow‐feather broilers under heat stress

This study investigated the effect of dietary resveratrol supplementation on growth performance, rectal temperature, and serum parameters of yellow‐feather broilers under heat stress. A total of 480 yellow‐feather broilers (28‐day‐old) were randomly allotted to five groups with six replicates. A thermoneutral group (TN) (24 ± 2°C) received a basal diet and another four heat‐stressed groups (37 ± 2°C for 8 hr/day and 24 ± 2°C for the remaining time) were fed the basal diet or basal diet with 200, 350, and 500 mg/kg resveratrol for 14 consecutive days. The results revealed that resveratrol supplementation improved average daily gain (p = 0.001), and decreased (p < 0.05) rectal temperature from d 3 when compared with heat‐stressed group without resveratrol. In addition, supplementation with resveratrol at 350 or 500 mg/kg lowered (p < 0.05) the contents of corticosterone, adrenocorticotropic hormone, cholesterol, triglycerides, uric acid, malonaldehyde, and activities of aspartate aminotransferase, alanine aminotransferase, and lactate dehydrogenase, increased (p < 0.05) the levels of triiodothyronine, the ratio of triiodothyronine to thyroxine, total protein, glutathione, and activities of alkaline phosphatase, total superoxide dismutase, catalase, and glutathione peroxidase, though with few fluctuation. In conclusion, supplementation with resveratrol can improve the growth performance by positively regulating serum metabolic parameters and alleviating tissue oxidant damage of broilers under heat stress.     

β‐hydroxy‐β‐methyl butyrate promotes leucine metabolism and improves muscle fibre composition in growing pigs

The aim of this study was to investigate the effects of excess leucine (Leu) vs. its metabolites α‐ketoisocaproate (KIC) and β‐hydroxy‐β‐methyl butyrate (HMB) on Leu metabolism, muscle fibre composition and muscle growth in growing pigs. Thirty‐two pigs with a similar initial weight (9.55 ± 0.19 kg) were fed 1 of 4 diets for 45 days: basal diet, basal diet + 1.25% L‐Leu, basal diet + 1.25% KIC‐Ca, basal diet + 0.62% HMB‐Ca. Results indicated that relative to the basal diet and HMB groups, Leu and KIC groups exhibited increased Leu concentrations and decreased concentrations of isoleucine, valine and EAAs in selected muscle (p < 0.05) and had lower mRNA levels of MyHC I and higher expression of MyHC IIx/IIb (p < 0.05), and there was no significant difference between the basal and HMB‐supplemented groups. Moreover, the mRNA expression levels of AMPKα and UCP3 were higher but the myostatin mRNA levels were lower in the soleus muscle of the HMB group than those from other groups (p < 0.05). These findings demonstrated that doubling dietary Leu content exerted growth‐depressing effects in growing pigs; dietary KIC supplementation induced muscular branched‐chain amino acid imbalance and promoted muscle toward a more glycolytic phenotype; while dietary HMB supplementation promoted the generation of more oxidative muscle types and increased muscle growth specially in oxidative skeletal muscle, and these effects of HMB might be associated with the AMPKα‐Sirt1‐PGC‐1α axis and mitochondrial biogenesis.     

Antioxidant supplementation of low‐protein diets reduced susceptibility to pulmonary hypertension in broiler chickens raised at high altitude

A reduced‐protein diet (designated as RPD) was prepared and its effects on growth performance and the development of pulmonary hypertension syndrome (PHS) were evaluated in broiler chickens compared to a normal‐protein diet (designated as NPD) or to the RPD supplemented with CoQ₁₀ alone (30 mg/kg) or in combination with vitamin E (30 mg/kg CoQ₁₀ + 100 mg/kg vitamin E). The RPD had 30 g/kg less crude protein compared to the NPD. A total of 208 1‐day‐old male broilers (Ross 308 strain) were used in a 42‐day trial. Serum concentrations of uric acid (UA) and nitric oxide (NO) significantly (p < 0.05) declined when chickens fed on the RPD. However, supplementing RPD with the antioxidants significantly (p < 0.05) increased the serum NO concentration. Although serum malondialdehyde (MDA) concentration was significantly (p < 0.05) higher in the RPD than the NDP, supplementing RPD with CoQ₁₀ and CoQ₁₀ + VE decreased serum MDA concentration to similar levels found in the NPD. Significant overexpression in GPX1 gene observed in the heart and lungs of broilers fed on the RPD, which was effectively restored by supplementation of CoQ₁₀. The right to total ventricular weight ratio (RV:TV) was significantly (p < 0.05) increased in birds fed the RPD, which concurred with an increase in mortality from pulmonary hypertension syndrome (PHS). However, a significant decline in mortality from PHS was observed when birds on RPD received CoQ₁₀ or CoQ₁₀ + VE. In conclusion, antioxidant supplementation effectively improves pulmonary hypertensive response in broiler chicken fed of reduced‐protein diets.     

Effects of chestnut tannins on intestinal morphology,barrier function,pro‐inflammatory cytokine expression,microflora and antioxidant capacity in heat‐stressed broilers

A study was conducted to evaluate the effects of chestnut tannins (CT) on intestinal morphology, barrier function, pro‐inflammatory cytokine expression, microflora and antioxidant capacity in heat‐stressed broilers. Four hundred 28‐day‐old male Ross 308 broilers were randomly assigned into four groups, with 10 replicates per group and 10 broilers per replicate. The broilers in the normal (NOR) group were kept at 22 ± 1°C and fed the basal diet, and each of the other three groups were treated with cyclic heat (33 ± 1°C from 0800 to 1800 and 22 ± 1°C from 1800 to 0800) and fed the basal diet with 0 (HT), 1 (CT1) or 2 (CT2) g of CT/kg of diet. The experiment lasted for 14 days. Compared with the HT group, broilers in the NOR and CT2 groups had higher (p < .05) average daily gain and villus height in the jejunum and lower serum d ‐lactate (p < .001) and diamine oxidase (p < .01) levels. The addition of 2 g CT/kg of diet increased the total antioxidant capacity (p < .001) and superoxide dismutase activities (p < .05) and zonula occludens‐1 mRNA expression level (p < .05) and decreased the malondialdehyde concentration (p < .01) and mRNA expression levels of interleukin‐6 (p < .001) and nuclear factor kappa B (p < .001) in the jejunal mucosa of heat‐stressed broilers. The populations of Escherichia coli and Clostridium in the jejunum (p < .01) and caecum (p < .05) of broilers in the HT group were higher than those in the NOR and CT2 groups. In conclusion, the addition of 2 g CT/kg of diet seemed to be a feasible means of alleviating the negative effects of heat stress on the growth performance and intestinal function of broilers.     

Methyl donors dietary supplementation to gestating sows diet improves the growth rate of offspring and is associating with changes in expression and DNA methylation of insulin‐like growth factor‐1 gene

The study aimed to investigate the effects of maternal dietary methyl donors on the performance of sows and their offspring, and the associated hepatic insulin‐like growth factor‐1 (IGF‐1) expression of the offspring. A total of 24 multiparous sows were randomly fed the control (CON) or the CON diet supplemented with methyl donors (MD) at 3 g/kg betaine, 15 mg/kg folic acid, 400 mg/kg choline and 150 μg/kg VB₁₂, from mating until delivery. After farrowing, sows were fed a common lactation diet through a 28‐days lactation period and six litters per treatment were selected to be fed until at approximately 110 kg BW. Maternal MD supplementation resulted in greater birthweight (p < 0.05) and increased the piglet weights (p < 0.01) and litter weights (p < 0.05) at the age of day 28, compared with that in CON group. The offspring pigs in the MD group had greater ADG (p < 0.05) and tended to lower F:G ratio (p = 0.07) compared with that of CON group from day 28 to 180 of age. The offspring pigs from MD group had greater serum IGF‐1 concentrations and expressions of hepatic IGF‐1 gene and muscular IGF‐1 receptor (IGF‐1r) protein at birth (p < 0.05), and greater hepatic IGF‐1 protein (p = 0.03) and muscular IGF‐1r gene expressions (p < 0.05) at slaughter, than that from the CON group. Moreover, the methylation at the promoter of IGF‐1 gene in the liver of newborn piglets and finishing pigs was greater in the MD group than that of the CON group (p < 0.05). In conclusion, maternal MD supplementation throughout gestation could enhance the birthweight and postnatal growth rate of offspring, associated with an increased expression of the IGF‐1 gene and IGF‐1r, as well as the altered DNA methylation of IGF‐1 gene promotor.     

Correlations between changes in intestinal microbiota composition and performance parameters in broiler chickens

Growing male Cobb broiler chickens were fed on diets supplemented with additives reported as able to influence intestinal microbiota composition. The diets used were a balanced commercial diet (no additive), inulin (20 g/kg), fructose caramel (FC, 20 g/kg) and the garlic derivative PTS‐O (propyl propane thiosulfonate, 45 and 90 mg/kg diet). The composition of the intestinal microbiota was analysed by qPCR at different points of the intestinal tract, and a number of nutritional parameters were also determined. The relative amounts of bacteroides (bacteroides/total bacteria) in the ileal contents correlated (p < 0.05) positively with faecal NDF, ADF, hemicellulose and cellulose digestibility. The relative amounts of Escherichia–Shigella (Escherichia–Shigella/total bacteria) in the crop contents correlated (p = 0.05) negatively with weight gain of broilers. Faecal N digestibility correlated (p < 0.05) negatively with total bacteria in the ileal contents of chickens. The relative amounts of Escherichia–Shigella (Escherichia–Shigella/total bacteria) in the caecal contents correlated (p = 0.05) negatively with faecal fat digestibility of broilers. Total bacteria in ileal or caecal contents of growing chickens correlated (p < 0.05) negatively with ileal N digestibility. The results here reported suggest that positive or negative correlations can be found between performance parameters and changes in intestinal microbiota composition of growing broiler chickens.     

Effects of Dietary Supplementation of β‐hydroxy‐β‐methylbutyrate on Sow Performance and mRNA Expression of Myogenic Markers in Skeletal Muscle of Neonatal Piglets

The effects of dietary β‐hydroxy‐β‐methylbutyrate (HMB) supplementation during gestation on reproductive performance of sows and the mRNA expression of myogenic markers in skeletal muscle of neonatal pigs were determined. At day 35 of gestation, a total of 20 sows (Landrace × Yorkshire, at third parity) were randomly assigned to two groups, with each group receiving either a basal diet or the same diet supplemented with 4 g/day β‐hydroxy‐β‐methylbutyrate calcium (HMB‐Ca) until parturition. At parturition, the total and live litter size were not markedly different between treatments, however, the sows fed HMB diet had a decreased rate of stillborn piglets compared with the sows fed the control (CON) diets (p < 0.05). In addition, piglets from the sows fed HMB diet tended to have an increased birth weight (p = 0.08), and a reduced rate of low birth weight piglets (p = 0.05) compared with piglets from the CON sows. Nevertheless, lower feed intake during lactation was observed in the sows fed the HMB diet compared with those on the CON diet (p < 0.01). The relative weights of the longissimus dorsi (LD) and semitendinosus (ST) muscle were higher (p < 0.05) in neonatal pigs from the HMB than the CON sows. Furthermore, maternal HMB treatment increased the mRNA levels of the myogenic genes, including muscle regulatory factor‐4 (MRF4, p < 0.05), myogenic differentiation factor (MyoD) and insulin‐like growth factor‐1 (IGF‐1, p < 0.01). In conclusion, dietary HMB supplementation to sows at 4 g/day from day 35 of gestation to term significantly improves pregnancy outcomes and increases the expression of myogenic genes in skeletal muscle of neonatal piglets, but reduces feed intake of sows during lactation.     

Effects of different stocking densities on growth performance,antioxidant ability,and immunity of finishing broilers

The study was conducted to evaluate the effects of different stocking densities on growth performance, antioxidant capacity, and immunity of broilers. One thousand four hundred and forty 22‐day‐old Lingnan Yellow broilers were randomly allotted to five different stocking density groups (8, 10, 12, 14, and 16 birds per m²). Each group consisted of three replicates. The results showed that 8 and 10 birds/m² groups had higher average daily feed intake (ADFI) than the others (p < 0.05). Heat shock protein 70 (HSP₇₀) in the group of 16 birds/m² had the highest levels (p < 0.05). The group of 16 birds/m² had the lowest total antioxidant capability (T‐AOC) and total superoxide dismutase (T‐SOD) activities in blood serum (p < 0.05), and significantly increased interleukin‐1β (IL‐1β) and interleukin‐4 (IL‐4) concentration compared to the groups of 8 and 10 birds/m² (p < 0.05). In liver, the group of eight birds/m² had higher T‐AOC levels than that of 12, 14, and 16 birds/m² (p < 0.05) and also higher catalase (CAT) activities than that of 14 and 16 birds/m² (p < 0.05); the group of 10 birds/m² had the highest T‐SOD activities among all groups (p < 0.05). In conclusion, the above results suggest that stocking density of broilers up to 8 or 10 birds/m² can prevent the negative effects on growth performance and welfare parameters in broilers.     

High dietary biotin levels affect the footpad and hock health of broiler chickens reared at different stocking densities and litter conditions

Responses to stocking density (SD), dietary biotin concentration and litter condition were evaluated on 2016 Ross 308 male broilers in the fattening period (day 22–day 42). The birds were placed in 48 pens with either dry or wet litter to simulate the final stocking density of 30 kg (12 broilers/m²; normal stocking density, NSD) and 40 kg (16 broilers/m²; high stocking density, HSD) of body weight (BW)/m² floor space. A corn–soybean meal‐based diet was supplemented with biotin to provide a normal (NB; 155 μg/kg) or high (HB, 1521 μg/kg) level of dietary biotin. There were six repetitions per treatment. The inappropriate moisture content of litter associated with HSD was avoided (p < 0.05) by good management (SD difference: dry litter, 6.65% vs. wet litter, 13.23%; 42 days), which made it advantageous (p < 0.01) for footpad (SD difference: dry litter, 0.118 vs. wet litter, 0.312; weekly average value) and hock health (SD difference: dry litter, 0.090 vs. wet litter, 0.303; weekly average value) of HSD birds, but not (p > 0.05) for growth and processing yield. In HSD, the biotin effect (gains, FCR) was significantly higher (p < 0.01) than in NSD. The similar response of HSD birds to supplemental biotin was observed (p < 0.05) for lesion scores of footpad and hock in particularly finishing chickens, and a significant interaction (p < 0.01) among stocking density, biotin supplementation and litter condition existed from 35 to 42 days of age. Taken together, increasing dietary biotin improves the performance and well‐being of broiler chickens stocked at high densities in litter‐independent and litter‐dependent manners respectively.     

Increased fatty acid β‐oxidation as a possible mechanism for fat‐reducing effect of betaine in broilers

Two hundred and forty 1‐day‐old male Arbor Acres broiler chickens were randomly assigned to five dietary treatments with six replicates of eight chickens per replicate cage for a 42‐day feeding trial. Broiler chickens were fed a basal diet supplemented with 0 (control), 250, 500, 750 or 1000 mg/kg betaine, respectively. Growth performance was not affected by betaine. Incremental levels of betaine decreased the absolute and relative weight of abdominal fat (linear P < 0.05, quadratic P < 0.01), low‐density lipoprotein cholesterol (LDL‐C), triglyceride (TG) and total cholesterol (TC) (linear P < 0.05), and increased concentration of nonesterified fatty acid (NEFA) (linear P = 0.038, quadratic P = 0.003) in serum of broilers. Moreover, incremental levels of betaine increased linearly (P < 0.05) the proliferator‐activated receptor alpha (PPARα), the carnitine palmitoyl transferase‐I (CPT‐I) and 3‐hydroxyacyl‐coenzyme A dehydrogenase (HADH) messenger RNA (mRNA) expression, but decreased linearly (P < 0.05) the fatty acid synthase (FAS) and 3‐hydroxyl‐3‐methylglutaryl‐CoA (HMGR) mRNA expression in liver of broilers. In conclusion, this study indicated that betaine supplementation did not affect growth performance of broilers, but was effective in reducing abdominal fat deposition in a dose‐dependent manner, which was probably caused by combinations of a decrease in fatty acid synthesis and an increase in β‐oxidation.     

Effect of lactic acid bacteria‐treated King grass silage on the performance traits and serum metabolites in New Zealand white rabbits (Oryctolagus cuniculus)

This study examined the effects of Lactobacillus plantarum and Pediococcus acidilactici‐treated silage of King grass (Pennisetum purpureophoides) on the productive traits and blood biochemistry of New Zealand white (NZW) rabbits. King grass was ensiled without or with L. plantarum (T1), P. acidilactici (T2) and P. acidilactici + L. plantarum (T3). A total of 72 male NZW rabbits (6 weeks) of similar weight and appearance were housed in groups in metallic cages in a completely randomized design. The performance traits, daily feed intake, body weight gain and feed convention ratio were not affected by the silage treatment. Triglyceride and alanine aminotransferase (ALT) concentration was increased (p < .05) in T2 (0.92 mmol/L) compared to the other treatments. The superoxide dismutase (SOD), phosphorous (P) and magnesium (Mg) increased (p < .05) in T1 (658.01 nmol/ml, 5.1 mg/kg and 2.43 mg/kg, respectively) compared to the control and other experimental groups. Cu and Mn decreased (p < .05), while Zn increased (p < .05) in the treated groups compared to the control. The CP decreased (p < .05) in the treatment groups compared to the control. Neutral detergent fibre (NDF) increased (p < .05) in T2 (54.40%) compared to the other treatments. The inoculation of lactic acid bacteria‐treated King grass silage supplementation positively affected rabbit performance and improved blood cholesterol profile, antioxidant status and improve nutrients digestibility.     

Effect of L‐theanine on meat quality,muscle amino acid profiles,and antioxidant status of broilers

This study investigated the effect of L ‐theanine on carcass traits, meat quality, muscle antioxidant capacity, and amino acid (AA) profiles of broilers. Three hundred 1‐day‐old Ross 308 male broilers were randomly allotted to five groups with six replicates. Birds were fed the basal diet or basal diet with 300, 600, 900, or 1,500 mg/kg L ‐theanine for 42 consecutive days. The results showed that L ‐theanine quadratically increased dressing percentage, eviscerated percentage, and leg muscle yield (p < .05). Meanwhile, drip loss, cooking loss, shear force, L*_24h, and muscle lactate content decreased quadratically in response to dietary L ‐theanine supplementation (p < .05), while pH_24h and muscle glycogen content were quadratically improved by L ‐theanine (p < .05). Notably, the contents of muscle malondialdehyde and protein carbonyl, and the activities of muscle total antioxidant capacity, catalase, and glutathione peroxidase decreased quadratically in response to dietary L ‐theanine supplementation (p < .05), suggesting that the oxidative stress level of muscle was decreased quadratically. Moreover, L ‐theanine quadratically increased the concentrations of most of muscle essential AA, nonessential AA, and flavor AA (p < .05). In conclusion, L ‐theanine can be used as a valuable feed additive to modulate carcass traits, meat quality, muscle antioxidant status, and AA profiles of boilers, and its optimum addition level is 600 mg/kg based on the present study.