Reduced fasting periods increase intestinal permeability in chickens

Fasting of up to 24 hr has been shown to increase intestinal permeability (IP) in chickens. The aim of this study was to determine whether fasting duration of 4.5 and 9 hr increased IP and whether l ‐glutamine (a non‐essential amino acid) supplementation before fasting provided some protection of barrier function as shown in other species. Ross 308 male broilers (n = 96) were fed either a control diet or the same diet supplemented with 1% glutamine from d0 to d38 post‐hatch. On d37, the birds were assigned to single‐bird metabolism cages and were fasted for either 0, 4.5, 9 or 19.5 hr. This study design was 2 × 4 factorial with two levels of glutamine and four levels of fasting. Birds in the 0‐hr fasting group had free access to feed. All birds had ad libitum access to water. To measure IP on day 38, following their respective fasting periods, birds were administered two separate oral gavages of fluorescein isothiocyanate dextran (FITC‐d) followed by lactulose, mannitol and rhamnose (LMR) sugars, 60 min apart. Whole blood was collected from the jugular vein 90 min post‐LMR sugar gavage. FITC‐d and L/M/R ratios were measured by spectrophotometry and high‐performance ionic chromatography respectively. Lipopolysaccharide (LPS) endotoxins in plasma of the birds fed the control diet were also measured using chicken‐specific LPS antibody ELISA. Serum FITC‐d and plasma L/M and L/R ratios for 4.5, 9 and 19.5 hr were significantly (p < .05) higher compared to the non‐fasting group. However, IP was not different in the glutamine‐supplemented group (p > .05) compared to the control group. LPS concentrations measured by the ELISA were below the detectable range. We conclude that fasting periods of 4.5 and 9 hr increased IP compared to non‐fasted birds and dietary glutamine supplementation did not ameliorate changes in IP.     

Gene expression and morphological changes in the intestinal mucosa associated with increased permeability induced by short‐term fasting in chickens

Short‐term fasting for 4.5 and 9 hr has been demonstrated to increase intestinal permeability (IP) in chickens. This study aimed to investigate the effects of 0, 4.5, 9 and 19.5 hr fasting on intestinal gene expression and villus‐crypt architecture of enterocytes in jejunal and ileal samples. On day 38, Ross‐308 male birds were fasted according to their group and then euthanised. Two separate intestinal sections (each 2 cm long, jejunum and ileum) were collected. One section was utilised for villus height and crypt depth measurements. The second section was snap‐frozen in liquid nitrogen for quantitative polymerase chain reaction (qPCR) analysis of tight junction proteins (TJP) including claudin‐1, claudin‐3, occludin, zonula occludens (ZO‐1, ZO‐2), junctional adhesion molecules (JAM) and E‐cadherin. Additionally genes involved in enterocyte protection including glucagon‐like peptide (GLP‐2), heat‐shock protein (HSP‐70), intestinal alkaline phosphatase (IAP), mammalian target of rapamycin (mTOR), toll‐like receptors (TLR‐4), mucin (MUC‐2), cluster differentiation (CD‐36) and fatty acid‐binding protein (FABP‐6) were also analysed. Normally distributed data were analysed using one‐way analysis of variance ANOVA. Other data were analysed by non‐parametric one‐way ANOVA. Villus height and crypt depth were increased (p < .05) only in the ileum after fasting for 4.5 and 9 hr compared with non‐fasting group. mRNA expression of claudin‐3 was significantly reduced in the ileum of birds fasted for 9 and 19.5 hr, suggesting a role in IP modulation. However, all other TJP genes examined were not statistically different from control. Nevertheless, ileal FABP‐6 of all fasted groups was significantly reduced, which could possibly be due to reduced bile acid production during fasting.     

Effects of lactulose supplementation on performance,blood profiles,excreta microbial shedding of Lactobacillus and Escherichia coli,relative organ weight and excreta noxious gas contents in broilers

This study was to evaluate the effects of lactulose supplementation on performance, blood profiles, excreta microbial shedding of Lactobacillus and Escherichia coli, relative organ weight and excreta noxious gas contents in broilers. A total of 720 ROSS 308 broilers with a body weight of 46 ± 0.1 g (1 day of age) were used in a 28‐d experiment. Broilers were randomly allotted to 4 experiment diets with 12 replicate pens and 15 birds per pen. Dietary treatments were as follows: NC, negative control (without antibiotic); PC, NC + 0.1% tiamulin; L1, NC + 0.1% lactulose; and L2, NC + 0.2% lactulose. Broilers were fed with phase 1 (1–8 day), phase 2 (9–18 day) and phase 3 (19–28 day) diets in the form of mash. During day 1–8, broilers fed the PC and L2 diets had higher (p < 0.05) body weight gain than those fed the NC diet. During day 19–28, broilers fed the L1 and L2 diets had lower (p < 0.05) feed intake than those fed the NC diet. The feed conversion ratio (FCR) was decreased (p < 0.05) in L1 treatment compared with NC treatment. Overall, the FCR was improved (p < 0.05) in all supplementation treatments compared with NC treatment. The apparently metabolizable nitrogen in L1 treatment was higher (p < 0.05) than that in NC treatment at day 28. The excreta Lactobacillus was increased and E. coli was decreased in PC and L2 treatments compared with NC treatment at day 28 (p < 0.05). The excreta NH₃, H₂S and acetic acid contents were decreased (p < 0.05) in L1 and L2 treatments compared with NC treatment. The relative weight of abdominal fat of broilers fed the PC diet was lowest (p < 0.05) compared with other treatments. In conclusion, this study indicated that dietary supplementation of 0.1% or 0.2% lactulose could improve growth performance, decrease excreta E. coli and excreta NH₃ and H₂S contents.     

Long‐term ingestion of low amylose/amylopectin ratio diet affects aspects of meat quality by changing muscle fibre characteristics in growing‐finishing pigs

Amylose plays important role in body health. It is controversial whether changing dietary amylose/amylopectin ratio (DAR) will improve meat quality in growing‐finishing pigs. A total of 48 Duroc × Landrace × Large White castrated male pigs (initial body weight 49.8 ± 2.8 kg) were randomly allotted to two treatments, and fed ad libitum either with a low DAR diet (LR, amylose/amylopectin: 12/88) or a high DAR diet (HR, amylose/amylopectin: 30/70) for 68 days. Feed intake was recorded every day, body weight was weighed at 46th and 68th day to calculate average daily gain (ADG), average daily feed intake (ADFI) and Feed:gain ratio. Blood was collected at ?30 min (fasting 12 hr), 60, 90, 120, 180 min postprandial at 64th day and then serum was obtained by centrifugation of blood at 1,500× g at 4°C. After pigs were slaughtered, samples such as longissimus dorsi, iliopsoas and semitendinosus were collected. Density, diameter and types of muscle fibres were analysed. Results showed that ADG, ADFI, Feed:Gain ratio, cross‐sectional area of longissimus dorsi muscle, backfat thickness, colour scores were not affected by DAR. Ingestion of LR diet increased the fasting glucose (p < 0.05) and insulin (p < 0.05) concentrations in serum. The drip loss and firmness were decreased significantly in LR vs. HR animals (p < 0.05). Densities of muscle fibre in longissimus dorsi, iliopsoas and semitendinosus were greater in LR pigs (p < 0.05). Moreover, ingestion of LR diet significantly increased myosin heavy chain (MyHC) IIa mRNA level and decreased MyHC IIb gene expression in longissimus dorsi muscle (LM) (p < 0.05). Therefore, intake of diet low in amylose/amylopectin ratio induces a better meat quality (lower drip loss and lower firmness), which could attribute to smaller myofibres, a shift to slower and/or more oxidative fibres.     

Physiological adaptive indicators in fasted neonate broiler chicks in response to calcium gluconate injection

Four hundred and eighty mixed‐sex broiler chicks aged 3 h after hatching were allotted according to a completely random design in a 6 × 2 × 2 factorial schedule into two groups of 12 replications of 20 chicks each. The main experimental factors were fasting for 0, 6, 12, 24, 36 and 48 h after chick placement and calcium gluconate (Ca‐glu) injection (0 and 0.6 ml). Live body weight (BW) of chicks decreased linearly (Y = 43.36–0.109BW_0 h, r² = 0.876) as neonatal fasting extended. Injection of 0.6 ml Ca‐glu at 3 h post‐hatching did not affect weight loss of chicks. Yolk residuals (YR) utilized linearly (Y = 5.75–0.062YR, r² = 0.956) by 0.062 g/h in neonate fasted chicks up to 48 h, showing no effect of Ca‐glu injection. Neonatal fasting periods longer than 12 h increased liver weight (p < 0.05). The mean absolute and proportional (% of BW_0 h) breast and leg weight were reduced linearly as neonatal fasting extended (p < 0.05). Serum glucose concentration increased up to 6 h and then reduced linearly to 150 mg/dl after 48‐h fasting. The Ca‐glu treatment influenced serum glucose level for a short period up to 6 h of fasting. Serum Ca concentration sharply increased up to threefolds in the birds received Ca‐glu injection resulting in acute hypercalcemia, then decreased to the initial level after 24‐h feed withdrawal (p < 0.05). The mean serum level for creatinine, uric acid, cholesterol, HDL, albumins and total proteins significantly increased during the fasting periods of 6 to 48 h and significantly elevated in the birds receiving 0.6‐ml Ca‐glu injection compared with the non‐treated chicks (p < 0.05). It was concluded that subcutaneous administration of 0.6 ml Ca‐glu in the chick's neck did not suitably support the increased metabolic demands for glucose and calcium in feed‐deprived neonate chicks.     

Effect of humic acids on intestinal viscosity,leaky gut and ammonia excretion in a 24 hr feed restriction model to induce intestinal permeability in broiler chickens

The purpose of this study was to evaluate the effect of humic acids (HA) on intestinal viscosity, leaky gut and ammonia excretion in a 24 hr feed restriction (FR) model to induce intestinal permeability in chickens. One‐day‐old male Cobb‐Vantress broilers were randomly allocated to one of two groups (n = 25 chickens), with or without 0.2% of isolated HA from worm‐compost, and placed in brooder batteries. Chicks had ad libitum access to water and feed for 14 days. Intestinal permeability was induced by 24 hr FR starting at 14 days. At 15 days of age, chickens in both groups were given an appropriate dose of fluorescein isothiocyanate dextran (FITC‐d) by oral gavage. Intestine and liver samples were also collected to evaluate viscosity and bacterial translocation (BT), respectively. An increase (p < .05) in intestinal viscosity was observed in the experimental group consuming 0.2% of HA and was confirmed in a published in vitro digestion model that simulates the chemical and physical conditions of the crop, proventriculus and intestine of chickens. Furthermore, the treated group also showed a significant reduction in FITC‐d, liver BT and ammonia in the manure. These results suggest that HA have a positive impact in intestinal integrity in chickens.     

Effect of oral administration of probiotics on growth performance,apparent nutrient digestibility and stress‐related indicators in Holstein calves

This study aimed to investigate the effect of dietary supplementation with Lactobacillus plantarum and Bacillus subtilis on growth performance, apparent nutrient digestibility and stress‐related indicators in dairy calves. Twenty‐four neonatal Holstein calves were randomly allocated to three treatments: a basal diet with no supplementation (control), the basal diet supplemented with 1.7 × 10¹⁰ CFU per head per day (CFU/h.d) of L. plantarum GF103 (LB group) or the basal diet supplemented with a mixture of L. plantarum GF103 (1.7 × 10¹⁰ CFU/h.d) and B. subtilis B27 (1.7 × 10⁸ CFU/h.d) (LBS group). Dry matter intake (DMI), average daily gain (ADG), feed conversation ratio (FCR), apparent digestibility of nutrients and stress‐related indicators were measured in this trail. The result indicated that no significant differences were observed in DMI or ADG (p > 0.05), but the FCR was improved in the LB group over the first 12 weeks (p > 0.05). The apparent digestibility of nutrients was not altered by probiotics in week 6 (p > 0.05), but the apparent digestibility of total phosphorus was significantly greater in the LB and LBS groups in week 8 (p > 0.05); additionally, an increase in the apparent digestibility of crude protein was detected in the LBS group (p > 0.05). Oral administration of L. plantarum alone improved the T‐lymphocyte transformation rate on days 58 and 62 (p > 0.05), while adding the mixture of L. plantarum and B. subtilis increased the T‐lymphocyte transformation rate (p > 0.05) but decreased the content of cortisol on day 58 (p > 0.05). No significant differences were detected between the LB and LBS groups in growth performance, apparent digestibility of nutrients and stress‐related indicators (p > 0.05). The results suggested that oral administration of L. plantarum improved growth performance, nutrient digestibility and relieved weaning stress in calves, but no additional effect was obtained by supplementation with B. subtilis.     

Effects of feeding different levels of corn steep liquor on the performance of fattening lambs

This study was conducted to assess the effect of feeding corn steep liquor (CSL) on in vivo digestibility, ruminal pH, ammonia and hydrolytic enzyme activities, blood metabolites, feed intake (FI) and growth performance in fattening lambs. The CSL is a by‐product of wet milling process of maize starch industry. The crude protein (CP), rumen‐degradable protein (RDP), lactic acid and metabolisable energy contents of this by‐product were 420, 324, 200 g/kg dry matter (DM) and 12.6 MJ/kg DM respectively. Twenty‐seven male Moghani lambs were assigned randomly into three groups of nine lambs each in a completely randomised design. Three iso‐energetic and iso‐nitrogenous diets containing different levels (0, 50 or 100 g/kg dry matter) of CSL were offered ad libitum three times a day. Forage to concentrate ratio of the diets was 30:70. With inclusion of CSL in diet, the contents of canola meal, fish meal, wheat bran, corn grain and sugar beet pulp were decreased. The contents of DM, ash‐free neutral detergent fibre (NDFom), ether extract, starch, Ca and S were numerically lower, but soluble protein, RDP and non‐fibre carbohydrates were greater in the diets containing CSL in comparison with the control diet. The lambs fed with the diets containing CSL had lower [linear (L), p < 0.06] digestibility coefficients of DM and NDFom as compared to those fed with the diet free of CSL. Ruminal ammonia‐N concentration increased (L, p < 0.05), but pH decreased (L, p < 0.05) with raising CSL level in diet. Carboxymethyl cellulase and filter paper‐degrading activities decreased (L, p < 0.05), while proteases activity increased (L, p < 0.05) as dietary rates of CSL increased. Microcrystalline cellulase and ɑ‐amylase activities were similar among the treatments. Within blood metabolites, only urea‐N concentration increased (L, p < 0.05) in the lambs receiving CSL as compared to those fed with diet without CSL. Dietary inclusion of CSL resulted in linear decreases (L, p < 0.05) in the intakes of DM, organic matter, CP, NDFom and ash‐free acid detergent fibre, and average daily gain. However, the feed conversion ratio was similar among the experimental animals. Overall, feeding CSL up to 100 g/kg diet DM in lamb resulted in reductions of rumen fibrolytic microbial enzyme activities, in vivo digestibility, FI and growth performance, but rumen proteases activity increased.     

Effects of dietary supplementation with a chlorella by‐product on the growth performance,immune response,intestinal microflora and intestinal mucosal morphology in broiler chickens

This study aimed to determine the effect of different dietary levels of a Chlorella by‐product (CBP) on the growth performance, immune response, intestinal microflora and intestinal mucosal morphology of broilers. In total, 480 one‐day‐old broiler chickens were randomly allotted to four dietary treatments with four replicated pens consisting of 30 chicks. The basal diet was formulated to be adequate in energy and nutrients. Three additional diets were prepared by supplementing 25, 50 or 75 g/kg of CBP to the basal diet. The diets were fed to the broilers ad libitum for 35 days. Result indicated that increasing inclusion level of CBP improved BW gain (linear, p < 0.05). There was no effect of inclusion level of CBP in diets on total cholesterol, triglyceride, aspartate aminotransferase and alanine aminotransferase levels during the 35 days. Plasma IgG, IgM and IgA concentrations increased (linear, p < 0.05) with inclusion level of CBP in diets. Supplementation of CBP in the diets increased (linear, p < 0.05) the concentrations of Lactobacillus in the caecal content and decreased (linear, p < 0.05) the concentrations of Escherichia coli and Salmonella in the caecal content. Villus height increased (linear and quadratic, p < 0.05) with inclusion level of CBP in diets. Crypt depth increased (quadratic, p < 0.05) with inclusion level of CBP, and a decreased villus height: crypt depth ratio (quadratic, p < 0.05) was observed as inclusion level of CBP in diets increased. The results of the current experiment indicate that dietary supplementation of CBP improves growth performance of birds. Dietary CBP has improving Lactobacillus spp. concentrations in the gastrointestinal tract, plasma immunoglobulin concentrations and intestinal mucosal morphology.     

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.     

Nigella sativa (black cumin seed) as a biological detoxifier in diet contaminated with aflatoxin B1

Aflatoxin B₁ (AFB₁) is a common feed contaminant that adversely affects bird performance and product quality. A total of 600 7‐day‐old quail chicks were randomly allotted to eight experimental groups in a completely randomized design with five replicate pens and 15 quails per pen. Experimental treatments including two levels of AFB₁ (0 and 2.5 mg/kg) and 4 levels of Nigella sativa (NS) (0, 0.5, 1.0 and 1.5% of diet) were offered from 7 to 35 days of age to quail chicks. Although feeding of AFB₁ impaired gain (G) and feed conversion ratio, dietary NS increased G (p < 0.05). Relative weight of bursa of Fabricius increased with incremental levels of NS (p < 0.05). AFB₁ decreased the size of heart, but incremental levels of NS increased the relative weight of heart (p < 0.05). The liver hypertrophy was observed in birds receiving AFB₁ (p < 0.05). The birds in AFB₁ group had smaller testes than other groups (p < 0.05). Hematocrit value in birds fed AFB₁ was lower than that in other groups (p < 0.05) and incremental levels of NS increased blood hematocrit (p < 0.05). Amount of malondialdehyde (MDA) in meat samples of the birds fed AFB₁ was higher than those did not receive toxin but incremental levels of NS decreased the MDA concentration in affected birds (p < 0.05). AFB₁ suppressed the humoral immunity of the birds while NS augmented the antibody titres against sheep red blood cell and Newcastle disease virus antigens (p < 0.05). AFB₁ decreased lactic acid bacteria (LAB) and spore‐forming bacteria (SFB) but increased Escherichia coli (E. coli; p < 0.05). However, NS increased LAB and SFB but decreased the E. coli populations (p < 0.05). This study revealed that NS as a biological detoxifier could relatively attenuate the negative effects of AFB₁ in quails.     

Carcass characteristics,chemical and fatty acid composition and oxidative stability of meat from broiler chickens fed black cumin (Nigella sativa) seeds

A study was conducted to investigate the dietary supplementation of black cumin seeds (BCS) on carcass characteristics, chemical and fatty acid (FA) composition and antioxidant properties of thigh and breast meat of broiler chickens at 42 days of age. Three hundred sixty 1‐day‐old broiler chickens were allocated to five dietary treatment groups (each group containing eight replicate pens with each pen containing nine broiler chickens): basal diet (control; CON), CON + 0.05 g/kg of bacitracin methylene disalicylate (AB), CON + 5 g/kg of BCS (low dose of BCS), CON + 10 g/kg of BCS (medium dose of BCS) and CON + 20 g/kg of BCS (high dose of BCS). Weight (g) of slaughtered birds (p = .03), hot carcass (p = .007), breast (p = .03), thigh (p < .001), wing (p = .06), neck (p = .01), liver (p = .09), abdominal fat (p = .01) and total edible parts (p = .01) increased or tended to increase due to BCS supplementation compared with the CON. The concentrations of dry matter, crude protein and ether extract in chicken thigh and breast meat increased (p = .038 to <.001) with increasing doses of BCS in diets. The ferric reducing antioxidant activity in blood and meat increased linearly with increasing doses of BCS in the diets. However, peroxide values in meat were not affected by BCS and AB on both days 1 and 7 of storage at 4°C. Supplementation of BCS increased the concentrations of C14:1, C18:3n‐6, C20:1, C20:2 FA and PUFA linearly (p < .05) and tended to increase (p = .098) the concentration of C18:2cis linearly. However, the concentrations of C16:0 and C16:1 FA decreased linearly with increasing doses of BCS in the diets. In conclusion, dietary supplementation of BCS at 20 g/kg diet may improve slaughter body weight, beneficial FA concentrations and antioxidant properties of broiler chicken meat.     

Alternate‐day fasting diet improves fructose‐induced insulin resistance in mice

Increased fructose consumption is linked to insulin resistance, weight gain, hyperlipidemia and hypertension. Although the advantages of several dietary restriction regimens have been demonstrated, the effects of alternate‐day fasting (ADF) on fructose‐induced insulin resistance have not yet been studied. This study is based on a new modification on ADF by combining the fructose‐rich solution (10% w/v) and regular mice diet. Mice were randomly allocated into four groups: ADF50% (50% restriction in chow food intake but ad libitum fructose drink), ADF100% (100% restriction for chow food but ad libitum fructose drink), control (ad libitum chow food intake plus tap water) and daily food and fructose (DFF) (had free access to both chow and fructose solution). Biweekly fasting blood sugar (FBS), glucose tolerance test (GTT) and insulin tolerance test (ITT) were conducted. All groups gained weight during the study (p < 0.05). Body weights of DFF and control groups did not differ from that of ADF groups, but ADF50% gained more (p < 0.01) weights than ADF100% through the study. Total calorie intake (feed + fast days) of ADF50% was higher than that of ADF100% (p < 0.001) and control (p < 0.03). In addition, ADF groups consumed more energy than the control and DFF groups in feed (ad libitum) days (p < 0.05). At the end of the study, the mean FBS levels in the control and ADF100% groups were similar and significantly lower in relation to that of DFF and ADF50% groups (p < 0.01). Measurements of area under the curve in GTT and ITT revealed that the ADF100% group was more insulin‐sensitive than the DFF and ADF50% groups. In conclusion, these data suggest that the ADF100% improves fructose‐induced insulin resistance in mice.     

Growth and haematological response of indigenous Venda chickens aged 8 to 13 weeks to varying dietary lysine to energy ratios

The effect of feeding varying dietary lysine to energy levels on growth and haematological values of indigenous Venda chickens aged 8 – 13 weeks was evaluated. Four hundred and twenty Venda chickens (BW 362 ± 10 g) were allocated to four dietary treatments in a completely randomized design. Each treatment was replicated seven times, and each replicate had fifteen chickens. Four maize–soya beans‐based diets were formulated. Each diet had similar CP (150 g/kg DM) and lysine (8 g lysine/kg DM) but varying energy levels (11, 12, 13 and 14 MJ ME/kg DM). The birds were reared in a deep litter house; feed and water were provided ad libitum. Data on growth and haematological values were collected and analysed using one‐way analysis of variance. Duncan's test for multiple comparisons was used to test the significant difference between treatment means (p < 0.05). A quadratic equation was used to determine dietary lysine to energy ratios for optimum parameters which were significant difference. Results showed that dietary energy level influenced (p < 0.05) feed intake, feed conversion ratio, live weight, haemoglobin and pack cell volume values of chickens. Dry matter digestibility, metabolizable energy and nitrogen retention not influenced by dietary lysine to energy ratio. Also, white blood cell, red blood cell, mean corpuscular volume, mean corpuscular haemoglobin and mean corpuscular haemoglobin concentration in female Venda chickens aged 91 days were not influenced by dietary lysine to energy ratio. It is concluded that dietary lysine to energy ratios of 0.672, 0.646, 0.639 and 0.649 optimized feed intake, growth rate, FCR and live weight in indigenous female Venda chickens fed diets containing 8 g of lysine/kg DM, 150 g of CP/kg DM and 11 MJ of ME/kg DM. This has implications in diet formulation for indigenous female Venda chickens.     

Effects of thermo‐resistant non‐starch polysaccharide degrading multi‐enzyme on growth performance,meat quality,relative weights of body organs and blood profile in broiler chickens

This research was conducted to study the performance and carcass parameters of broiler chickens fed diets supplemented with heat‐treated non‐starch polysaccharide degrading enzyme. A total of 432 one‐day old Ross 308 broiler chickens were allocated to five treatments: (i) CON (basal diet), (ii) E1: CON + 0.05% multi‐enzyme, (iii) E2: CON + 0.1% multi‐enzyme, (iv) E3: CON + 0.05% thermo‐resistant multi‐enzyme and (v) E4: CON + 0.1% thermo‐resistant multi‐enzyme, each treatment consisted of six replications and 12 chickens in each replication. The chickens were housed in three floor battery cages during 28‐day experimental period. On days 1–7, gain in body weight (BWG) improved by feeding the diets supplemented with thermo‐resistant multi‐enzyme. On days 7–21 and 1–28, chickens fed the diets containing thermo‐resistant multi‐enzyme showed improved (p < 0.05) BWG and feed conversion ratio (FCR) compared to CON group. Supplementing the diets with multi‐enzyme or thermo‐resistant multi‐enzyme affected the percentage of drip loss on d 1 (p < 0.05). Drip loss percentage on days 3 and 5 and also meat colour were not affected significantly. Supplementing the diets with multi‐enzyme or thermo‐resistant multi‐enzyme did not affect the relative weights of organs but compared to CON group, relative weight of breast muscle increased and abdominal fat decreased (p < 0.05). Among measured blood constituents, chickens fed supplemented diets with thermo‐resistant multi‐enzyme showed higher (p < 0.05) IgG. Counts of red and white blood cells and lymphocyte percentage were not affected. In conclusion, the results demonstrated that supplementing pelleted diets with thermo‐resistant multi‐enzyme improved performance of broiler chickens.     

Changes in tissue free amino acid pools in growing chickens fed thermally treated vetch diets

A three‐day assay was developed to evaluate the effect of autoclaving on protein quality of vetch as an alternative to classical growth methods. Male chickens (n = 10/diet) were given approximately isonitrogenous diets based on raw or autoclaved vetch for 3 days. Samples of plasma, muscle and liver were obtained for free amino acid analysis. Heating vetch depressed growth (11.9 vs. 23.2 g/d; p < 0.05). Plasma methionine and histidine increased (0.05 < p < 0.06), while gluconeogenic amino acids tended to decrease (p < 0.10) after heating. Muscle free amino acids did not change except for a trend to increased methionine (p = 0.06) in birds fed autoclaved vetch. In liver, most essential amino acids, glycine, proline and tyrosine increased markedly with heated vetch diet. Correlations between plasma and muscle free amino acids were poor compared with those between plasma and liver free amino acids. Liver free amino acid pool was more sensitive than muscle or plasma pool to amino acid inflow modifications after vetch heating.     

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.     

Effect of dietary threonine on laying performance and intestinal immunity of laying hens fed low‐crude‐protein diets during the peak production period

Threonine (Thr) may be a limiting amino acid for laying hens fed diets with lowered protein level. An experiment was conducted to examine laying performance, and the intestinal immune function of laying hens provided diets varying in digestible Thr levels. Lohmann Brown laying hens (n = 480), 28 weeks of age, were allocated to six dietary treatments, each of which included five replicates of 16 hens. Dietary crude protein (CP) 16.18% diet was offered as the positive control diet. L‐Thr was added to the negative diet (14.16% CP) by 0, 1.0, 2.0, 3.0 and 4.0 g/kg, corresponding 0.44%, 0.43%, 0.49%, 0.57%, 0.66% and 0.74% digestible Thr. At 40 weeks, a reduction in CP level decreased laying performance (p < 0.05). In the low CP, increasing dietary Thr increased (p < 0.05) egg production and egg mass and rose to a plateau between 0.57% and 0.66%. The hens fed 0.66% Thr showed the lowest value (p < 0.05) of feed conversion ratio (FCR). Serum level of uric acid showed the lowest values (p < 0.05) at 0.57–0.66%. In addition, serum‐free Thr maximized (p < 0.05) between 0.66% and 0.74%. Digestive trypsin activity decreased (p < 0.05) when hens fed the low‐CP diet compared with hens fed CP (16.18%) and hens fed 0.57–0.66%. Expressions of ileal MUC2 mRNA maximized (p < 0.05) at 0.66% Thr. Occludin mRNA increased with increasing Thr level (p < 0.05). sIgA mRNA reached to the maximum level (p < 0.05) at 0.66% and 0.74% Thr. INF‐γ mRNA reached to the lowest level (p < 0.05) at 0.65%. Expressions of ileal IL‐2, IL‐6, IL‐1β mRNA decreased with increasing Thr level (p < 0.05). In conclusion, Thr supplementation resulting in optimal laying performance and stimulated the mucosal immune system, suggesting that it is a limiting amino acid in the low‐crude‐protein diet of laying hens during the peak production period.     

Montmorillonite improved the intestinal mucosal barrier functions of laying hens in late production

This study was conducted to investigate the effects of dietary supplementation with montmorillonite (MMT) on performance, intestinal endotoxin concentration, gut mucosal oxidation status, intestinal morphology and permeability, and immunological barrier function of laying hens during late production. Four hundred and eighty 75‐week‐old laying hens (Lohmann Brown) were randomly assigned to five treatments with eight replicates per treatment and 12 hens in each replicate. The hens were fed the basal diet supplemented with 0 (control), 0.3, 0.6, 0.9, or 1.2 g MMT/kg for 70 days. Compared with the control, supplemented with 0.9 g MMT/kg increased egg mass significantly (p < 0.05) during weeks 1–5 of the experiment. Supplemented with 0.6 and 0.9 g MMT/kg also increased the endotoxin concentration in the ileal digesta (p < 0.05), but decreased the MDA concentration in the ileum significantly (p < 0.05). The T‐AOC in the jejunum of the group fed 0.3 g MMT/kg was significantly increased (p < 0.05). Compared with the control, the villus height:crypt depth of ileum from the groups fed 0.6, 0.9, and 1.2 g MMT/kg increased significantly (p < 0.05). The sIgA concentration of jejunum in the groups fed 0.6 and 0.9 g MMT/kg was higher (p < 0.05) than the control. The MMT supplementation linearly increased (p < 0.05) the mRNA expression of claudin‐1 and claudin‐5 in the jejunum. Dietary MMT supplementation down‐regulated the mRNA expression of NF‐κB P65 and TNF‐α in the jejunum in a linear and quadratic manner (p < 0.05). The IL‐1β mRNA expression of jejunum in the group fed 0.6 g MMT/kg was lower (p < 0.05) than the control. In conclusion, dietary supplementation with MMT may improve the gut barrier functions and suggests that 0.9 g/kg of MMT in diets may be the optimal supplemental level for laying hens in late production.