Toxicokinetics and absolute oral bioavailability of melamine in broiler chickens

The objective of this study was to investigate the toxicokinetic characteristics of melamine in broilers due to the limited information available for livestock. Melamine was then administered to broiler chickens at an intravenous (i.v.) or oral (p.o.) dosage of 5.5 mg/kg of body weight, and plasma samples were collected up to 48 h. The concentration of melamine in each plasma sample was analyzed using liquid chromatography‐tandem mass spectrometry (LC‐MS/MS). Melamine was measurable up to 24 h after i.v. and p.o. administration. A one‐compartment model was developed to describe the toxicokinetics of melamine in broilers. Following i.v. administration, the values for the elimination half‐life (t_1/2β), the volume of distribution (V_d), and the clearance (CL) were 4.42 ± 1.02 h, 00.52 ± 0.18 L/kg, and 0.08 ± 0.01 L/h/kg, respectively. The absolute oral bioavailability (F) was 95.63 ± 3.54%. The results suggest that most of the administered melamine is favorably absorbed from the alimentary tract and rapidly cleared by the kidneys in broiler chickens.     

Effects of guanidinoacetic acid on growth performance,creatine metabolism and plasma amino acid profile in broilers

The objective of this study was to assess the effects of guanidinoacetic acid (GAA) on growth performance, creatine deposition and blood amino acid (AA) profile on broiler chickens. In Exp. 1, a total of 540 one‐day‐old Arbor Acres male broilers (average initial body weight, 45.23 ± 0.35 g) were divided randomly into five treatments with six replicates of 18 chicks each. Broilers were fed corn–soybean meal‐basal diets supplemented with 0, 600, 800, 1,000 or 1,200 mg/kg GAA for 42 days respectively. Results showed that dietary GAA inclusion increased average daily gain (ADG) and improved gain‐to‐feed ratio (G:F) from 1 to 42 days (p < 0.01). However, average daily feed intake was unaffected by dietary supplementation of GAA. As GAA inclusion increased, the contents of creatine in plasma and kidney were increased (linear, p < 0.01), while the contents of GAA and creatine in liver were decreased (linear, p < 0.01). Similarly, GAA supplementation was inversely related to concentrations of most essential AA in plasma. In Exp. 2, a total of 432 one‐day‐old Arbor Acres male broilers (average initial body weight, 39.78 ± 0.58 g) were divided randomly into four treatments with six replicates of 18 chicks each. Birds were fed a corn–soybean meal‐basal diet supplemented with 0, 200, 400 or 600 mg/kg GAA for 42 days respectively. Dietary inclusion of 600 mg/kg GAA significantly increased ADG and G:F of broilers (p < 0.05). In conclusion, dietary supplementation of 600–1,200 mg/kg GAA can effectively improve the growth performance in broiler chickens by affecting creatine metabolism and utilization efficiency of essential AA, and 600 mg/kg GAA is the minimum dose for improving performance.     

Effect of soybean peptides on growth performance,intestinal structure and mucosal immunity of broilers

Five‐hundred 1‐day‐old broilers were randomly assigned to five groups, 100 chickens for each group. From group 1 to 3, 80, 120 and 200 mg/kg soybean peptides was added to the diets respectively; in the fourth group, 3.2 mg/kg genramycin was added; and the fifth group was the control without soybean peptides and antibiotics. At the age of 28 and 49 days, the number of goblet cells (GC), intestine intraepithelial lymphocyte, immunoglobulin A‐forming cells, the ratio of villous height and crypt depth (V/C) of broiler’s duodenum, jejunum and cecum were observed by the application of haematoxylin and eosin or histochemistry staining. The results indicated that soybean peptides added with 80–120 mg/kg could increase daily weight gain, the number of GC and V/C. Soybean peptides could modulate intestinal mucosal immunity of broilers.     

Relieving effect of Artemisia argyi aqueous extract on immune stress in broilers

This experiment aimed to investigate the relieving action of Artemisia argyi aqueous extract (AAE) on immune stress in broiler chickens. A 2 × 2 factorial design was used to test the effect of 2 dietary treatments (adding 0 or 1000 mg/kg AAE) and 2 immune stress treatments (injecting saline or lipopolysaccharide (LPS)). A total of 96 one‐day‐old Arbor Acres (AA) broilers were randomly divided into four treatment groups with six replicates, four birds in each replicate. Broilers in Treatment groups 1 and 2 were fed with the basal diet, and those in Treatment groups 3 and 4 were fed with the experimental diet supplemented with 1000 mg/kg AAE. On days 14, 16, 18 and 20, broilers in both Treatments 1 and 3 were injected intra‐abdominally with LPS solution at the dose of 500 μg LPS per kg BW with the LPS dissolved in sterile saline at a concentration of 100 μg/ml, and those in Treatments 2 and 4 were injected intra‐abdominally with equal amount of sterile 0.9% saline. Blood samples were collected on days 21 and 28. The results showed that dietary supplementation of AAE prevented reductions in average daily gain (ADG) and average daily feed intake (ADFI) of broilers caused by LPS on d 15–21. On day 21, the injection of LPS increased serum adrenocorticotropic hormone (ACTH) and corticosterone (CORT); meanwhile, feeding AAE reduced the rise of CORT caused by LPS. Immune parameters such as interleukin‐1 (IL‐1), interleukin‐2 (IL‐2), interleukin‐6 (IL‐6), immunoglobulin G (IgG) and immunoglobulin A (IgA) were also improved by LPS, but the content of IL‐2 and IgG in broilers fed with AAE diet was significantly lower than that of broilers fed with control diet. All the data suggested that diets supplemented with AAE could relieve the immune stress response of broilers.     

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.     

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.     

Effects of epigallocatechin gallate on lipid metabolism and its underlying molecular mechanism in broiler chickens

The objective of this study was to investigate the effects of epigallocatechin gallate (EGCG) on fat metabolism and to establish the molecular mechanism of these effects in broilers. Seventy‐two 28‐day‐old male Ross 308 broiler chickens were divided into three groups with different levels of EGCG supplementation for 4 weeks: normal control (NC) group, L‐EGCG (a low‐level supplement of EGCG, 40 mg/kg body weight daily) and H‐EGCG (a high‐level supplement of EGCG, 80 mg/kg body weight daily). After 4 weeks of oral administration, EGCG significantly reduced the level of abdominal fat deposition in broilers. The serum triglycerides and low‐density lipoprotein cholesterol of chickens in H‐EGCG group were also significantly decreased compared with the NC group, and the high‐density lipoprotein cholesterol was notably increased at the same time. Moreover, the vital role of the liver and abdominal adipose tissue in lipid metabolism of poultry animals was examined through gene expression and enzyme activities related to fat anabolism and catabolism in these organs. Our data show that EGCG supplementation for 2 weeks significantly downregulated the expression of fatty acid synthesis and fat deposition‐related genes, and upregulated the expression of genes involved in fatty acid β‐oxidation and lipolysis genes. Simultaneously, the activities of hepatic fatty acid synthesis enzymes (fatty acid synthase and acetyl CoA carboxylase) were significantly decreased, and the activity of carnitine palmitoyl transferase‐1 was notably elevated. The results suggest that EGCG could alleviate fat deposition in broilers through inhibiting fat anabolism and stimulating lipid catabolism in broilers.     

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.     

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.     

Estimate of choline nutritional requirements for chicks from 1 to 21 days of age

Choline is an essential nutrient in poultry diets because it performs various important metabolic functions. The objective of this study was to re‐evaluate the choline requirements of male broiler chickens from 1 to 21 days of age at two levels of methionine. Two assays using 2,160 Cobb^® chickens (1,080 in each assay) were conducted. The study design was completely randomized and consisted of six treatments and six replicates, with 30 animals per experimental unit. The semipurified basal diet was formulated with corn, soya bean meal, soya protein concentrate, starch and sugar, providing 390 mg/kg choline and 0.593% digestible methionine (requirement level) in Assay 1 and a reduction of about one‐quarter in the requirement level of digestible methionine (0.440%) in Assay 2. Choline chloride (62.5%) was added by a supplementation technique to both basal diets to compose crescent levels of choline supplementation (715, 1,040, 1,365, 1,690 and 2,015 mg/kg). The weight gain responses were fitted using quadratic polynomial (QP) and broken‐line (BL) models. The ideal intake of choline (mg/bird.day) was estimated from the first intercept of the QP with the BL plateau (BL + QP). The results showed that the diet with the 25% reduction in digestible methionine limited the maximum weight gain by approximately 10%. The choline requirements of broilers from 1 to 7, 1 to 14 and 1 to 21 days of age were 27,013, 44,458 and 62,535 mg/bird.day, respectively, for the requirement level of digestible methionine and 26,796, 41,820 and 56,578 mg/bird.day for the broilers receiving the diet with the 25% reduction in digestible methionine.     

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.     

Bromocriptine inhibits salsolinol‐induced prolactin release in male goats

The secretion of prolactin (PRL) is under the dominant and tonic inhibitory control of dopamine (DA); however, we have recently found that salsolinol (SAL), an endogenous DA‐derived compound, strongly stimulated the release of PRL in ruminants. The aim of the present study was to clarify the inhibitory effect of DA on the SAL‐induced release of PRL in ruminants. The experiments were performed from late June to early July. Male goats were given a single intravenous (i.v.) injection of SAL (5 mg/kg body weight (BW)), a DA receptor antagonist (sulpiride, 0.1 mg/kg BW), or thyrotropin‐releasing hormone (TRH, 1 µg/kg BW) before and after treatment with a DA receptor agonist (bromocriptine), and the effect of DA on SAL‐induced PRL release was compared to that on sulpiride‐ or TRH‐induced release. Bromocriptine completely inhibited the SAL‐induced release of PRL (P < 0.05), and the area under the response curve (AUC) for a 120‐min period after the treatment with bromocriptine was 1/28 of that for before the treatment (P < 0.05). Bromocriptine also completely inhibited the sulpiride‐induced release (P < 0.05). The AUC post‐treatment was 1/17 that of pre‐treatment with bromocriptine (P < 0.05). Bromocriptine also inhibited the TRH‐induced release (P < 0.05), though not completely. The AUC post‐treatment was 1/3.8 that of pre‐treatment (P < 0.05). These results indicate that DA inhibits the SAL‐induced release of PRL in male goats, and suggest that SAL and DA are involved in regulating the secretion of PRL. They also suggest that in terms of the regulatory process for the secretion of PRL, SAL resembles sulpiride but differs from TRH.     

Combined effects of guanidinoacetic acid,coenzyme Q10 and taurine on growth performance,gene expression and ascites mortality in broiler chickens

High levels of guanidinoacetate acid (GAA) deteriorate growth response in broiler chickens. We propose using coenzyme Q₁₀, an antioxidant, and taurine (TAU), a methyl donor, to cope with the situation when high level of GAA included in diet. GAA was supplemented at 0 (control), 0.75, 1.5 and 2.25 g/kg in isoenergetic and isonitrogenous diets and fed to broilers (Cobb 500) from 1 to 40 days post‐hatch. Three additional diets were prepared by adding CoQ₁₀ (40 mg/kg), TAU (40 mg/kg) or their combination (both CoQ₁₀ and TAU at 40 mg/kg) to the 2.25 g/kg GAA group. The experimental design used was a completely randomized design. While weight gain (p = 0.038) and feed conversion ratio (p = 0.024) improved when GAA added at 1.5 g/kg, higher supplementation (2.25 g/kg) deteriorated these responses. These responses, however, were significantly restored by using CoQ₁₀, TAU or their combination. Abdominal fat deposition was significantly decreased when TAU added to broiler diets by virtue of upregulating peroxisome proliferator‐activated receptor alpha. Supplementing broiler diets with CoQ₁₀ and TAU or their combination significantly decrease ascites mortality. In conclusion, CoQ₁₀ and TAU have shown beneficial effects when high level of GAA included in broiler diets.     

Plasma pharmacokinetics and tissue depletion of cyromazine and its metabolite melamine following oral administration in laying chickens

The study was designed to characterize the plasma pharmacokinetics and tissue depletion profiles (including eggs) of cyromazine (CYR) in chickens following oral administration alone or in combination with melamine (MEL). In order to assess the pharmacokinetic profile of CYR, chickens were administered 1 or 10 mg/kg (single oral doses), whereas residue studies were conducted in chickens fed CYR alone (5 or 10 mg/kg) or CYR (5 mg/kg) and MEL (5 mg/kg) for a period of 14 days. Estimates for the apparent volume of distribution (1.66 L/kg), clearance (7.17 mL/kg/min), and elimination half‐life (2.82 h) were derived by noncompartmental analyses. The highest concentration of CYR occurred in liver but fell below detectable limits within 3 days following drug withdrawal from feed. Combined feeding of MEL with CYR did not significantly alter CYR tissue levels. CYR residues were detected only in egg white and were undetectable at the 2nd day postadministration. No MEL was found in eggs unless it had been added to the feed, and when present, it almost exclusively restricted to the egg white. Based upon the results of this initial study of CYR pharmacokinetics and residue depletion, it appears that use of CYR as a feed additive either alone (5 or 10 mg/kg) or in combination with MEL (both agents at 5 mg/kg) does not produce unsafe residue levels in edible products as long as appropriate withdrawal periods are followed for tissues (3 days) and eggs (2 days). However, our results indicate that adoption of a zero‐day withdrawal period should be reconsidered in light of these results.     

Effects of Yucca schidigera extract on growth performance and antioxidative function of small intestine in broilers

Dietary Yucca schidigera extract (YSE) could enhance immune function in broilers, which was attributed primarily to its saponin components. However, YSE also contains phenolic compounds which possess antioxidant ability. This study tested the effects of YSE on growth performance of broilers, its antioxidative enzyme activities and corresponding gene expressions in the small intestine. A total of 128 15‐day‐old broilers were randomly assigned to 4 treatments: corn‐soya bean meal as the basal control diet or the basal diet containing either 100, 200 or 300 mg/kg of YSE. Each treatment consisted of four replicate pens with eight broilers per pen. The experiment lasted 28 days which was divided into a grower period (day: 15–28) and a finisher period (day: 29–42). On day 28 and day 42 body weight (BW), feed intake (FI) and feed conversion rate (FCR) were recorded. Duodenum, jejunum and ileum were collected to analyse superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx) activities, malondialdehyde (MDA) concentrations, total antioxidant capacity (T‐AOC) and gene expressions of SOD, CAT, GPx. The results showed that during the grower period a diet including 100 mg/kg YSE improved CAT capacity in the ileum, tended to increase activities of GPx in the duodenum, and further showed enhancing tendencies in SOD and GPx abilities in ileum. Gene expressions of CAT, SOD and GPx in the ileum tended to upregulate at 100 mg/kg YSE level. In the finisher period and over the whole period, all YSE groups had a reduced FI compared to the control group without compromising BW; 100 and 200 mg/kg YSE significantly improved FCR. In conclusion, the improved growth performance of broilers during the finisher period may be due to enhanced antioxidative ability in the grower period with YSE supplementation. This study provided evidence of using YSE as an additive to enhance growth in broilers.     

Effect of different levels of copper nanoparticles and copper sulphate on performance,metabolism and blood biochemical profiles in broiler chicken

A study was conducted to investigate the influence of copper administration in ovo to chicken embryos and/or supplied in drinking water to growing chickens in the form copper nanoparticles (Cu‐NP) or copper sulphate (CuSO₄). The fertilised eggs were assigned to three groups (n = 50 per group): control (not injected), injected with 50 mg/kg Cu‐NP or with 50 mg/kg CuSO₄ at day 1 of incubation. Thereafter, 126 one‐day‐old broiler chickens were randomly assigned to seven post‐hatched groups: control not injected and not provided with Cu in the drinking water, injected with 50 mg/kg Cu‐NP + 20 mg/kg in water, not injected + 20 mg/kg Cu‐NP in water, injected with 50 mg/kg CuSO₄ + 20 mg/kg in water, not injected + 20 mg/kg CuSO₄ in water, injected with 50 mg/kg Cu‐NP and injected with 50 mg/kg CuSO₄. The experiment was carried out from day 1 to 35 post‐hatching. The in ovo injection of Cu improved the final body weight, average daily gain and feed conversion ratio in relation to the control group. Conversely, the provision of Cu in the drinking water had less of an effect on growth performance in comparison with the injected groups. A significant improvement was shown in energy and nitrogen utilisation, being better for Cu‐NP than CuSO₄. The cholesterol, urea and glucose levels in the blood were reduced by Cu‐NP treatment in relation to the other groups. The relative weight of the liver was decreased, while bursa of Fabricius was increased in Cu groups in relation to the control group. Cu excretion was only reduced in chickens injected with 50 mg/kg Cu‐NP + 20 mg/kg in water. The immune‐related genes were not affected by the treatments. The in ovo injection of Cu‐NP might improve broiler performance more efficiently than the injection of CuSO₄ or the provision of Cu‐NP and/or CuSO₄ in drinking water.     

Effects of berberine on the growth performance,antioxidative capacity and immune response to lipopolysaccharide challenge in broilers

This study evaluated the effects of berberine on growth performance, immunity, haematological parameters, antioxidant capacity, and the expression of immune response‐related genes in lipopolysaccharide (LPS)‐challenged broilers. We assigned 120 one‐day‐old male broilers (Ross 308) to two treatment groups; each group included two subgroups, each of which included six replicates of five birds per replicate. The experiment used a 2 × 2 factorial arrangement with berberine treatment (0 or 60 mg/kg dietary) and challenge status [injection of saline (9 g/L w/v) or LPS (1.5 mg/kg body weight)] as the main factors. On days 14, 16, 18 and 20, broilers were intraperitoneally injected with LPS or physiological saline. Blood and liver samples were collected on day 21. Dietary berberine supplementation significantly alleviated the compromised average daily gain and average daily feed intake (p < 0.05) caused by LPS. The LPS challenge led to increased lymphocyte and white blood cell (WBC) counts, malondialdehyde (serum and liver) content, and immunoglobulin G and M, tumour necrosis factor‐α (TNF‐α) and interleukin‐1β (IL‐1β) expression (p < 0.05) and significantly reduced serum total superoxide dismutase (T‐SOD) activity (p < 0.05). Dietary berberine significantly mitigated the LPS‐induced decreases in the mRNA expression of nuclear factor‐kappa B (NF‐κB), TNF‐α, IL‐1β, inducible nitrite synthase and cyclooxygenase‐2 (p < 0.05) in the liver. In conclusion, berberine supplementation has a positive effect on LPS challenge, which may be related to the increase in antioxidant enzyme activity and inhibition of both NF‐κB signalling and the expression of inflammatory mediators.     

Pharmacokinetics of florfenicol in blunt‐snout bream (Megalobrama amblycephala) at two water temperatures with single‐dose oral administration

The pharmacokinetics and residue elimination of florfenicol (FFC) and its metabolite florfenicol amine (FFA) were studied in healthy blunt‐snout bream (Megalobrama amblycephala, 50 ± 10 g). The study was conducted with a single‐dose (25 mg/kg) oral administration at a water temperature of 18 or 28°C, while in the residue elimination study, fish were administered at 25 mg/kg daily for three consecutive days by oral gavage to determine the withdrawal period (WDT) at 28°C. The FFC and FFA levels in plasma and tissues (liver, kidneys and muscle) were analysed using high‐performance liquid chromatography (HPLC). A no‐compartment model was used to analyse the concentration versus time data of M. amblycephala. In the two groups at 18 and 28°C, the maximum plasma concentration (C_max) of FFC was 5.89 and 6.21 μg/ml, while the time to reach C_max (T_max) was 5.97 and 2.84 hr, respectively. These suggested that higher temperature absorbed more drug and more quickly at M. amblycephala. And the elimination half‐life (T_1/2kβ) of FFC was calculated as 26.75 and 16.14 hr, while the total body clearance (CL) was 0.09 and 0.15 L kg^?1 hr^?1, and the areas under the concentration–time curves (AUCs) were 265.87 and 163.31 μg hr/ml, respectively. The difference demonstrated that the elimination rate of FFC in M. amblycephala at 28°C was more quickly than that at 18°C. The results of FFA showed the same trend in tissues of M. amblycephala. After multiple oral doses (25 mg/kg daily for 3 days), the k (eliminate rate constant) of FFA in M. amblycephala muscle was 0.017, the C₀ (initial concentration) was 3.07 mg/kg, and the WDT was 10 days (water temperature 28°C).     

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.