Interaction of neuropeptide Y receptors (NPY1, NPY2 and NPY5) with somatostatin on somatostatin-induced feeding behaviour in neonatal chicken

1. The present study was conducted to investigate whether brain somatostatin increases feed intake in neonatal chickens. The mediating role of neuropeptide Y receptors on feed intake induced by somatostatin was investigated.

2. In this study, seven experiments were designed, each with four treatment groups (n = 44 in each experiment). In Experiment 1, chicks received control solution and 0.5, 1 and 2 nmol of somatostatin through intracerebroventricular (ICV) injection. In experiments 2, 3 and 4, chickens were ICV injected with control solution and 1.25, 2.5 and 5 μg of B5063 (NPY₁ receptor antagonist), SF22 (NPY₂ receptor antagonist) and SML0891 (NPY₅ receptor antagonist), respectively. In experiment 5, 6 and 7 chickens received ICV injection of B5063, SF22, SML0891, with a co-injection of + somatostatin, control solution and somatostatin. The cumulative feed intake was measured until 120 min post injection.

3. Somatostatin significantly increased feed intake in FD3 chicks. Both B5063 and SML0891 dose-dependently decreased feed intake compared with the control group, while SF22 led to a dose-dependent increase in feed intake. In addition, the hyperphagic effect of somatostatin significantly decreased with co-injection of B560 plus somatostatin (p < 0.05), but SF22 and SML0891 had no effect on feed intake induced by somatostatin in chicks (p > 0.05).

4. Based on the results of this study, it is likely that somatostatin increased feed intake and NPY₁ receptor acts as a mediator in hyperphagic effect of somatostatin in neonatal chicks.     

Serotonin-induced hypophagia is mediated via α2 and β2 adrenergic receptors in neonatal layer-type chickens

1. Serotoninergic and adrenergic systems play crucial roles in feed intake regulation in avians but there is no report on possible interactions among them. So, in this study, 5 experiments were designed to evaluate the interaction of central serotonergic and adrenergic systems on food intake regulation in 3 h food deprived (FD₃) neonatal layer-type chickens.

2. In Experiment 1, chickens received intracerebroventricular (ICV) injection of control solution, serotonin (56.74 nmol), prazosin (α₁ receptor antagonist, 10 nmol) and co-injection of serotonin plus prazosin. In Experiment 2, control solution, serotonin (56.74 nmol), yohimbine (α₂ receptor antagonist, 13 nmol) and co-injection of serotonin plus yohimbine were used. In Experiment 3, the birds received control solution, serotonin (56.74 nmol), metoprolol (β₁ receptor antagonist, 24 nmol) and co-injection of serotonin plus metoprolol. In Experiment 4, injections were control solution, serotonin (56.74 nmol), ICI 118.551 (β₂ receptor antagonist, 5 nmol) and serotonin plus ICI 118.551. In Experiment 5, control solution, serotonin (56.74 nmol), SR59230R (β₃ receptor antagonist, 20 nmol) and co-administration of serotonin and SR59230R were injected. In all experiments the cumulative food intake was measured until 120 min post injection.

3. The results showed that ICV injection of serotonin alone decreased food intake in chickens. A combined injection of serotonin plus ICI 118.551 significantly attenuated serotonin-induced hypophagia. Also, co-administration of serotonin and yohimbine significantly amplified the hypophagic effect of serotonin. However, prazosin, metoprolol and SR59230R had no effect on serotonin-induced hypophagia in chickens.

4. These results suggest that serotonin-induced feeding behaviour is probably mediated via α₂ and β₂ adrenergic receptors in neonatal layer-type chicken.     

Consequence of dopamine D2 receptor blockade on the hyperphagic effect induced by cannabinoid CB1 and CB2 receptors in layers

1. Endocannabinoids (ECBs) and their receptors play a regulatory function on several physiological processes such as feed-intake behaviour, mainly in the brain. This study was carried out in order to investigate the effects of the dopaminergic D1 and D2 receptors on CB1/CB2 ECB receptor-induced hyperphagia in 3-h feed-deprived neonatal layer chickens.

2. A total of 8 experiments were designed to explore the interplay of these two modulatory systems on feed intake in neonatal chickens. In Experiment 1, chickens were intracerebroventricular (ICV) injected with control solution, l-DOPA (levo-dihydroxyphenylalanine as precursor of dopamine; 125 nmol), 2-AG (2-arachidonoylglycerol as CB₁ receptor agonist; 2 µg) and co-administration of l-DOPA (125 nmol) plus 2-AG (2 µg). Experiments 2–4 were similar to Experiment 1 except birds were injected with either 6-OHDA (6-hydroxydopamine as dopamine synthesis inhibitor; 150 nmol), SCH23390 (D1 receptor antagonist; 5 nmol) and AMI-193 (D2 receptor antagonist; 5 nmol) instead of l-DOPA, respectively. Additionally, Experiments 5–8 followed the previous ones using the same dose of l-DOPA, 6-OHDA and dopamine antagonists except that birds were injected with CB65 (CB2 receptor agonist; 5 µg) instead of 2-AG. Coadministrations were at the same dose for each experiment. Cumulative feed intakes were measured until 120 min after each injection.

3. ICV administration of 6-OHDA and AMI-193 significantly attenuated 2-AG-induced hyperphagia. Interestingly, the hyperphagic effect of CB65 was significantly attenuated by administration of l-DOPA, whereas the administration of 6-OHDA and AMI-193 together amplified the hyperphagic effect of CB65.

4. It was concluded that cannabinoid-induced feeding behaviour is probably modulated by dopamine receptors in neonatal layer-type chickens. It seems that their interaction may be mediated by the D2-dopamine receptor.     

Physiological responses to central and peripheral injection of polyinosinic-polycytidylic acid in chicks

1. The purpose of the present study was to determine if intracerebroventricular (ICV) and intraperitoneal (IP) injection of polyinosinic-polycytidylic acid (poly I:C), a viral mimetic that binds to toll-like receptor-3 (TLR3), affects food intake, voluntary activity, cloacal temperature, plasma corticosterone (CORT) and glucose concentrations, and crop emptying rate in chicks (Gallus gallus).

2. Both ICV and IP injection of poly I:C significantly decreased food intake.

3. IP but not ICV injection of poly I:C significantly suppressed voluntary activity, whereas ICV injection decreased time spent sitting. Both ICV and IP injection of poly I:C significantly increased plasma CORT and glucose concentration. Neither ICV nor IP injection of poly I:C significantly affected cloacal temperature.

4. In addition, ICV injection of poly I:C significantly reduced crop emptying rate, whereas IP injection had no effect.

5. These results suggested that central TLR3 is related to anorexia, stress response and retardation of crop emptying while peripheral TLR3 is related to anorexia, change in behaviour and stress responses during viral infection in chicks.     

The efficacy of a standardised product from dried leaves of Solanum glaucophyllum as source of 1,25-dihydroxycholecalciferol for poultry

1. Chemical characterisation of an extract of Solanum glaucophyllum (SG) leaves affirmed the predominant presence of 1,25-dihydroxycholecalciferol (1,25(OH)₂D₃) glycosides. The compound 1-(ß-D-glucopyranosyl)-1α,25-dihydroxycholecalciferol was isolated for the first time from a natural source.

2. Vitamin D activity of the extract was confirmed by the calcaemic properties shown in a quail eggshell bioassay. The results suggested a 1,25(OH)₂D₃ bioavailability of approximately 15%.

3. A broiler feeding experiment replicated in time was carried out with 6 treatments. A basic control diet containing 25 μg cholecalciferol/kg was supplemented with 2.5 and 5 μg free 1,25(OH)₂D₃/kg, with a product based on dried SG leaves (Panbonis) providing 10 μg of 1,25(OH)₂D₃-glycosides/kg, with two concentrations of an SG extract providing 8.8 and 37.8 μg of 1,25(OH)₂D₃-glycosides/kg.

4. Tibia breaking strength and stiffness were numerically greater in all treatment groups with free 1,25(OH)₂D₃ and with SG products compared to controls, though the overall treatment effects only had probabilities in the range of P = 0.07 to P = 0.1. Values for both characteristics increased progressively, with additions of synthetic 1,25(OH)₂D₃; values with the dried SG product were similar to those with 5 μg synthetic 1,25(OH)₂D₃/kg.

5. Plasma calcium was mildly elevated (P < 0.05) in treatment groups. The SG extract treatment containing 37.8 μg 1,25(OH)₂D₃/kg gave the highest plasma calcium concentration and lowest bodyweight, signs of marginal hypervitaminosis D. Plasma 1,25(OH)₂D₃ concentrations were in the normal range for all treatments.

6. Tibial dyschondroplasia occurred in only one replicate. The incidences were 31% in controls but considerably lower or zero with all other treatments.

7. Bioavailability of 1,25(OH)₂D₃ in the SG product seemed to be higher in broiler chickens than in Japanese quails.

8. It is concluded that the inclusion of the dried SG product as a source of vitamin D₃ in broiler diets at a dietary concentration of 1 g/kg, providing 10 μg 1,25(OH)₂D₃/kg, is safe and efficacious.     

Cardiovascular effects of angiotensin‐II in chickens

1. Mature WL cockerels with permanent cannulae in brachial artery and vein were restrained in an isolated sling. Blood pressure (BP) and heart rate (HR) were continuously recorded. When the chickens were habituated to the sling, injections began. In each experiment the cockerels were injected intravenously 6 times at 6 min intervals.

2. In the first experiment 6 injections of 0.5 nmol[Aspl,Val5]ANG‐II/kg body weight were given.

3. In the second experiment oxytocin (OT) antagonist ([d(GH2)5‐O‐Me‐Tyr2,Thr4,Tyr9,Orn8]VT) at a dose of 2 nmol/kg, was injected for the first 3 and 0.5 nmol ANG‐II/kg for the last 3 injections. Such OT‐antagonist pretreatment completely abolishes the vasodepressor (VDP) response to neurohypophysial pep‐tides in chickens.

4. Injections of ANG‐II resulted in a biphasic effect on BP, an initial brief fall followed by a prolonged rise. During the hypotensive phase, tachycardia developed which turned into bradycardia as the hypertensive phase appeared. No tachyphy‐laxis of the VDP effect of ANG‐II was evident with repeated injections.

5. OT‐antagonist pretreatment had no effect on the VDP response to ANG‐II.

6. These results suggest that, unlike relaxation of chicken aortic ring in in vitro preparations, there is no tachyphylaxis of the VDP response to ANG‐II, in vivo. Furthermore, the neurohypophysial peptides are not involved in the VDP effect of ANG‐II because pretreatment with an OT‐antagonist had no effect on it. The baroreflex buffers the effects of ANG‐II on vascular tone by affecting HR.

7. As ANG‐II is secreted during hypovolaemia, the biphasic haemodynamic response peptides may have a compensatory role following volume contraction.     

The effects of dietary 1, 25-dihydroxycholecalciferol and hydroalcoholic extract of Withania somnifera root on bone mineralisation,strength and histological characteristics in broiler chickens

1. This study was carried out to investigate the effects of 1, 25-dihydroxycholecalciferol (1, 25 (OH)₂ D₃) and a hydroalcoholic extract of Withania somnifera (WS) root on performance, mineral retention, bone mineralisation, bone mechanical and bone histological characteristics of broiler chicks.

2. A 2 × 3 × 2 factorial experiment consisted of a positive control diet with adequate Ca and a negative control diet (Ca concentration reduced by 30%), three concentrations of WS (0, 75 and 150 mg/kg diet), and two concentrations of 1, 25 (OH)₂ D₃ (0 and 0.5 μg/kg diet).

3. A total of 600 male one-d-old Ross 308 broiler chicks were randomly distributed into 60 floor pens, with 10 birds each. Each treatment was replicated 5 times (50 birds). Diets were given ad libitum from one to 42 d of age. On d 21 and 42, one bird per replicate was killed and tibiae were removed.

4. Dietary treatments did not affect feed intake and feed conversion. The maximum body weight gain (2475 g) was noted in birds fed on a diet adequate in Ca and supplemented with 75 mg/kg WS.

5. The Ca and P retentions were significantly higher in birds that were given a diet with 30% less Ca. Supplementation of 150 mg/kg WS significantly improved Ca retention in birds receiving a negative control compared to those given a positive control diet (83.0% vs. 66.3%). Ca retention was significantly improved with the addition of 0.5 μg/kg 1, 25 (OH)₂ D₃ to the diet containing 75 mg/kg WS, regardless of dietary Ca concentration (79.5 vs. 73.3 and 77.9 vs. 68.9).

6. On d 21, birds that received WS had significantly higher tibia Ca compared to those of controls. No significant effects on tibia Ca were noted at 42 d. Birds given a negative control diet supplemented with 75 mg/kg WS and 0.5 μg/kg 1, 25 (OH)₂ D₃ displayed a similar tibia Ca compared to those given only 150 mg/kg WS. Dietary supplementation of 1, 25 (OH)₂ D₃ significantly increased tibia Ca and tibial mineralised zone width in birds at 42 d of age.

7. Tibia shear force and stiffness were significantly increased by supplementation of WS. Administration of 1, 25 (OH)₂ D₃ resulted in a significantly lower width of the proliferative zone at 21 d of age. Reduction of the Ca supply significantly reduced the mineralised zone and cortical thickness at this age.

8. The present study showed that WS supplementation improved Ca retention, bone calcification and mechanical properties with no adverse effects on performance. Also, synergistic effects of WS and 1, 25 (OH)₂ D₃ were observed on Ca retention and bone calcification.     

Effect of dietary contents of cholecalciferol, 1α,25‐dihydroxycholecalciferol and 24,25‐dihydroxycholecalciferol on blood concentrations of 25‐hydroxycholecalciferol, 1α,25‐dihydroxycholecalciferol,total calcium and eggshell quality

1. Withdrawal of cholecalciferol (D₃) supplement from a layers diet drastically reduced blood 25‐hydroxycholecalciferol (25‐OH‐D₃), 1α,25‐dihydroxycholecalciferol (calcitriol) and egg specific gravity (SG) within two weeks, followed by a decrease in blood total calcium (Ca).

2. Doubling the D₃ supplement in the control diet (27.5 μg or 1100 IU/kg) almost linearly increased the circulating concentration of 25‐OH‐D₃ without raising the concentration of calcitriol, Ca, or egg SG.

3. Replacing D₃ by the optimal concentration of calcitriol (5 μg/kg diet) improved egg SG after 21 weeks of treatment without increasing blood calcitriol or total Ca.

4. By itself, 24,25‐dihydroxycholecalciferol [24,25‐(OH)₂D₃] was unable to maintain normal blood levels of calcitriol, Ca or egg SG and, when added together with calcitriol in the diet, tended to elevate blood Ca but suppress the beneficial effect of calcitriol on shell quality, with little or no effect on blood calcitriol.     

Effects of dietary calcium content and vitamin D source on skeletal properties in growing turkeys

1. The aim of the study was to investigate the effects of feeding fast growing turkeys with differentiated dietary calcium (Ca) content, and the partial replacement of vitamin D₃ in the feed with 25-hydroxycholecalciferol (25(OH)D₃), on skeletal properties.

2. One-day-old Big-6 male turkeys (n?=?1008) were randomly divided into 4 groups, and two subgroups were created within each group. The groups were differentiated with 4 levels of Ca provision in the feed, namely 85% of the National Research Council (NRC) recommendation (Group Ca₁); 95% as above (Group Ca₂); 105% as above (Group Ca₃); and 115% as above (Group Ca₄). The first subgroup received the recommended dosage of cholecalciferol (vitamin D₃ subgroup) in the feed, while in the second subgroup (Hy-D subgroup), half of the dosage of cholecalciferol was replaced with 25(OH)D₃. At the ages of 4, 8, 12 and 20 weeks, 7 turkeys from each subgroup were randomly selected and killed to obtain the right tibia for densitometric, geometric and mechanical analyses.

3. This study showed advantageous effects of increased calcium supply in the diet on skeletal system properties, that were increased and produced the most desirable traits in turkeys receiving 95%, 105% and 115% of the NRC calcium recommendation. Benefits resulting from administration of 25(OH)D₃ in the diet were also obtained in the skeletal formation of turkeys, and the most advantageous effects were present in the group receiving 105% of recommended dietary Ca.

4. Effects on the metabolic response of the skeleton of turkeys to manipulation of dietary calcium content and vitamin D₃ source were the most evident in the groups between 4 and 12 weeks of life, and demonstrated a limited ability to induce a positive influence on bone properties at advanced stages of the production cycle by alteration of these dietary factors.     

Molecular weight and amino acid composition of fowl delta‐globulin

1. The molecular weight of delta‐globulin was estimated chromato‐graphically to be about 10,700 daltons.

2. Ultracentrifuge experiments at 2.7 × 10⁵ g gave values of s _{20, W} = (1.49 + 0.16C) × 10^?13 s for the sedimentation coefficient and D_{20 w} = (1.12 + 0.19c) × 10^?6 cm² s^?1 for the diffusion coefficient, c being the protein concentration (g/100 ml).

3. According to the Svedberg equation, these imply a molecular weight of 12,470 daltons, assuming [v_bar] = 0.74 ml/g.

4. Using refractometer measurements of protein concentration it was found that E ^1% _1cm (278 nm) = 5.57 at pH 7.8.

5. From the ultraviolet absorption spectrum of the protein in 0.1 N NaOH it was concluded that the molecule probably contains four tyrosine residues and no tryptophan.

6. On this basis a revised amino acid composition is given.     

Possible role of central interleukins on the anorexigenic effect of lipopolysaccharide in chicks

1. The purpose of the present study was to determine if central interleukin-1β (IL1β), interleukin-6 (IL6) and interleukin-8 (IL8) affect feeding behaviour in chicks (Gallus gallus) and examine if central interleukins are related to the lipopolysaccharide (LPS)-induced anorexia.

2. Intra-abdominal (IA) injection of LPS significantly suppressed feeding behaviour and significantly increased mRNA expression of IL1β and IL8 in the diencephalon when compared to the control group, while IL6 tended to be increased.

3. Intracerebroventricular (ICV) injection of 200 ng IL1β significantly decreased food intake at 60 min after the injection while IL6 and IL8 had no effect.

4. IA injection of these ILs (200 ng) had no effect on food intake in chicks.

5. ICV injection of 200 ng IL1β did not affect water intake and plasma corticosterone concentration, suggesting that central IL1β might not be related to the regulation of drinking behaviour and the hypothalamus–pituitary–adrenal axis.

6. The present study demonstrated that central IL1β but not IL6 and IL8 might be related to the inhibition of feeding in chicks.     

Hydrogenated oil decreases tissue concentrations of n‐6 polyunsaturated fatty acids and may contribute to dyschondroplasia in broilers

1. In a factorial design of dietary treatments, male Ross broilers were given diets containing soyabean oil, hydrogenated soya‐bean oil (as a source of trans‐fatty acids) or feed fat with either 0 or 300 μg of added D‐biotin/kg.

2. Growth to 28 d was not influenced by the dietary treatments.

3. Length of tibiotarsal bones was reduced (P<0.05) and severity of leg bone cartilage lesions, characteristic of dyschondroplasia, was highest (P<0.05) in broilers fed on diets containing hydrogenated soyabean oil.

4. Feeding hydrogenated soyabean oil lowered (P< 0.05) the concentrations of C₂₀:_4n6 and the ratios of C_20:4n6/C_18:2n6 in liver and growth plate cartilage.

5. Growth plate cartilage from birds affected with dyschondroplasia contained lower proportions of prostaglandin precursor fatty acids compared with normal growth plate.

6. It is speculated that an inhibition of prostaglandin biosynthesis brought about by the presence of trans‐fatty acids might contribute to the occurrence of lesions similar to dyschondroplasia.     

Evaluation of nutrient equivalency of microbial phytase in hens in late lay given maize–soybean or distiller's dried grains with solubles (DDGS) diets

1. An experiment was conducted with 360 Lohmann LSL-Classic White Leghorn layers (64 weeks old) to evaluate the effects of supplementation of microbial phytase on production, egg quality, bone, selected manure parameters and feed costs.

2. Experimental diets were formulated as follows: (1) maize–soybean (CS), (2) CS+300 units of phytase (FTU)/kg diet which was formulated to recoup only calcium and available phosphorus equivalency for phytase (CS+PHY_Ca+P), (3) CS+300 FTU/kg diet which was formulated to recoup total nutrient equivalency for phytase (CS+PHY_total), (4) CS+100 g/kg distiller's dried grains with solubles (DDGS), (5) DDGS+300 FTU/kg diet which was formulated to recoup only calcium and available phosphorus equivalency for phytase (DDGS+PHY_Ca+P), or (6) DDGS+300 FTU/kg diet which was formulated to recoup total nutrient equivalency for phytase (DDGS+PHY_total).

3. Each dietary treatment was assigned to 4 replicate groups with 3 cages and 5 hens per cage. The hens were provided with feed and water ad libitum. The experiment lasted for 8 weeks.

4. CS+PHY_Ca+P, CS+PHY_total, DDGS+PHY_Ca+P and DDGS+PHY_total diets supplemented with phytase provided similar percentage egg production, egg weight, egg mass, exterior egg quality, initial and final body weight compared with phytase-free diets.

5. However, supplementation of phytase to the experimental diets and calculation of the total nutrient equivalency for enzyme caused increased feed intake and decreased feed conversion ratio and Haugh unit.

6. No differences in manure dry matter, crude ash, total nitrogen, tibia crude ash, calcium and phosphorus contents were found among the experimental diets. On the other hand, manure total phosphorus content was significantly decreased in the DDGS diet and diets supplemented with phytase in comparison to the CS diet.

7. It was concluded that the addition of microbial phytase to the CS-based diets or diets with DDGS of hens in late lay and using Ca and available P equivalency of enzyme in feed; formulation may provide an economic benefit and decrease the amount of phytate P excretion in the manure without compromising production and egg quality parameters.     

Effect of Melissa officinalis supplementation on growth performance and meat quality characteristics in organically produced broilers

1. A trial was conducted to study the effect of Melissa officinalis supplementation on organic broiler performance and meat chemical, microbiological, sensory and nutritional quality.

2. Male and female day-old Ross 308 chicks were fed on a standard commercial diet containing 0, 2.5, 5 or 10 g/kg feed ground M. officinalis for 84 d before slaughter.

3. Weight gain and feed conversion ratio were significantly improved in the broilers receiving either 5 or 10 mg M. officinalis/kg feed.

4. Inclusion of M. officinalis did not affect muscle chemical and fatty acid composition.

5. On the basis of microbiological and sensory experimental data and subsequent extension of meat shelf life, M. officinalis did not reduce the microbial populations of the meat, but was effective in limiting lipid oxidation.     

Growth performance of crossbred naked neck and normal feathered laying hens kept in tropical villages

1. Two experiments were conducted to develop naked neck (Na/na) and normal feathered (na/na) crossbreds and compare their growth performance, linear body measurements and carcass characteristics in the first and second filial generations.

2. In the first experiment, 4 indigenous naked neck males (Na/na) were mated to 36 Lohmann commercial females (na/na) in a ratio of 1:9. The two genotypes (Na/na, na/na) were allocated randomly according to batches of hatch, sire lines and sex to three different villages.

3. In the second experiment, 10 males and 100 females of F₁ Na/na birds were selected and mated inter se in a ratio of 1:10. The three genotypes (Na/Na, Na/na and na/na) were compared in a randomised complete block design experiment, with the three villages, hatch and sex as blocks and the three genotypes as treatments. F₁ Na/na birds had significantly higher (P < 0.05) feed conversion ratio, body weight, body weight gain, linear body measurements, survivability and carcass yield than their na/na counterparts.

4. In the F₂ generation, Na/Na and Na/na birds had significantly higher (P < 0.05) feed conversion ratio, body weight, body weight gain, linear body measurements, survivability and carcass yield compared to their na/na counterparts.

5. The birds showing the naked neck phenotype appeared to show superior performance compared to normal feathered birds and could be exploited for potential utilisation in local poultry production.     

Effects of fermented corni fructus and fermented kelp on growth performance,meat quality,and emission of ammonia and hydrogen sulphide from broiler chicken droppings

1. Corni fructus is the fruit of Cornus officinalis, a dogwood species. This study was conducted to prepare fermented corni fructus preparation (FCFP) and fermented kelp (FK) from corni fructus and by-products of Laminaria japonica fermented with Bacillus subtilis and Aspergillus oryzae.

2. The effects of dietary FCFP and FK as replacer of oxytetracycline (OTC) on growth performance, meat composition, meat oxidative stability, and emissions of ammonia (NH₃) and hydrogen sulphide (H₂S) from broiler chicken droppings were investigated.

3. A total of 140 d-old broiler chicks were randomly allotted to 4 dietary treatments including control, OTC (0.05 g/kg), FCFP (5 g/kg), and FK (5 g/kg).

4. Overall, inclusion of FCFP resulted in lower weight gain and feed intake during the overall experimental period. Broilers fed FCFP diets tended to have lower crude fat and higher crude ash content in the carcasses.

5. In the fresh state, the malondialdehyde (MDA) value of broiler meat was lower in the FK supplemented group. At one week, meat from broilers fed antibiotic and FK diets had lower MDA values, whereas at 2 weeks broiler meat from all dietary treatment groups had lower MDA values than the control.

6. Dietary supplementation with FK significantly reduced faecal NH₃ emissions throughout the experimental period, whereas dietary OTC and FCFP supplementation increased NH₃ emissions at 2 and 4 weeks. There were no significant effects of dietary treatments on H₂S emissions throughout the experimental period, except during week one, when FCFP supplementation reduced the emission.

7. In conclusion, dietary supplementation with 5 g/kg FK improved the oxidative stability of broiler meat and reduce faecal NH₃ emissions without affecting growth performance.     

Inter-batch contamination and potential sources of vancomycin-resistant Enterococcus faecium on broiler farms

1. Vancomycin-resistant Enterococcus faecium (VRE_fm) has recently spread among Swedish broiler farms. The objectives were to investigate VRE_fm persistence within barns between flocks, and to determine whether day-old chicks, feed or forklift trucks used for loading crates could be identified as a means of transmission.

2. Faeces were collected for selective culture from 12 farms (9 culture-positive, 3 culture-negative as determined by prior monitoring), and samples were collected from the barn environment before and after cleaning and disinfection, from forklift tyres, hatcheries and feed.

3. VRE_fm was isolated only from previously known VRE_fm-positive farms. The proportions of culture-positive environmental samples were 75% (9 out of 9 farms) prior to and 31% (7 out of 9 farms) after cleaning/disinfection. Five out of 6 samples from forklift tyres were culture-positive. No VRE_fm were isolated from feed or hatcheries. The majority of 27 vanA gene positive isolates showed similar banding patterns by SmaI restriction digestion and pulse-field gel electrophoresis. No consistent differences were observed regarding management between VRE_fm-positive and negative farms.

4. We conclude that VRE_fm contaminates barns and remains present between flocks. Forklift trucks are one possible means of transmission between farms.     

Potential of a commercially available water acidification product for reducing Campylobacter in broilers prior to slaughter

1. This study investigated the potential of a commercially available acidified water treatment (PWT) for reducing the number of Campylobacter in vitro and other bacteria in the gut of live broilers.

2. In vitro tests indicated that PWT was highly effective for reducing Campylobacter jejuni and Campylobacter coli at the recommended concentration in water, reducing populations by greater than 7 log₁₀ CFU/ml after 24 h exposure. The decrease in the number of Salmonella serovar Enteritidis and Escherichia coli was not significant.

3. Addition of PWT to the broiler drinking water for the first 7 d, 2 d before and 2 d after each feed change and at feed withdrawal prior to slaughter or only after feed withdrawal had no effect on the number of Campylobacter in caecal samples on farm before thinning and depopulation compared to untreated controls.

4. Although PWT was effective for reducing Campylobacter in water, the results suggest that it does not reduce the number of Campylobacter in the caeca of broilers prior to slaughter under the conditions used in the study.     

Immune-modulatory effects of dietary Saccharomyces cerevisiae cell wall in broiler chickens inoculated with Escherichia coli lipopolysaccharide

1. An experiment was conducted to study the effect of yeast (Saccharomyces cerevisiae) cell wall (YCW) supplemented in diets of broiler chickens challenged with Escherichia coli lipopolysaccharide (LPS).

2. One-day-old broiler chicks were randomly distributed into 24 cages (6 replicate cages; 8 birds/cage) and were inoculated with 0 or 1 mg/kg body weight E. coli-LPS (d 4 and 9) and 0 or 500 mg YCW/kg feed, resulting in a 2 × 2 factorial arrangement of treatments. Experimental diets did not include coccidiostats, in-feed antibiotics or enzymes.

3. On d 21, the inoculation of E. coli-LPS reduced weight gain and feed intake and increased feed conversion ratio (FCR) of birds, an effect maintained until 28 d. In contrast, chickens given diets with YCW improved the FCR at both 21 and 28 d of age.

4. E. coli-LPS challenge reduced the relative weight of bursa of Fabricius, except when chickens were given YCW, which resulted in an interaction. Supplementation of broiler diets with YCW exacerbated the cellular immune response as measured by the delayed cutaneous hypersensitivity response test.

5. The results of this study suggested a benefit on feed efficiency when YCW was added to diets fed to broiler chickens challenged with E. coli-LPS. Part of the mode of action of YCW might be related to better maintenance of immune status in response to microbial challenge.     

Inclusion levels and modes of whole grain incorporation into wheat-based rations differentially influence the performance of broiler chickens

1. The objective was to compare three whole grain (WG) inclusion levels (7.5, 15 and 30%) offered to broiler chickens by three modes of WG incorporation: (i) pre-pellet WG inclusion, (ii) post-pellet WG inclusion as a blend of WG and pelleted concentrate and (iii) post-pellet WG inclusion where WG and pelleted concentrate were provided in separate feed trays against a ground-grain, wheat-based control diet.

2. Ten dietary treatments were offered to 6 replicate cages (6 birds per cage) of male Ross 308 chickens from 7 to 28 d post-hatch. The effects of treatment on relative gizzard weights, gizzard contents, pancreatic weights and pH of gizzard digesta were monitored. Parameters of growth performance, nutrient utilisation (apparent metabolisable energy [AME], metabolisable to gross energy [ME:GE] ratios, nitrogen [N] retention and N-corrected AME [AMEn]), apparent starch and protein (N) digestibility coefficients and disappearance rates in for small intestinal segments and concentrations of free amino acids in plasma taken from the anterior mesenteric vein were determined.

3. Whole grain feeding (WGF) did not influence weight gain, but 30% post-pellet blended and 15 and 30% post-pellet separated treatments significantly depressed (P < 0.05) feed intakes while the 30% post-pellet separated treatment improved (P < 0.01) feed conversion ratios (FCR). WGF regimes significantly increased relative gizzard weights.

4. Overall, WGF generated profound responses in AME, ME:GE ratios, N retention and AMEn that were highly correlated with relative gizzard weights. In general, WGF improved starch and protein (N) digestibilities and again there were some correlations with these outcomes and relative gizzard weights.

5. Post-pellet WG inclusions where WG and pelleted concentrate were offered separately provided chickens with the opportunity to choice feed. Birds showed a preference for the relatively high-protein pelleted concentrate and at 30% WG, this resulted in an improvement in FCR of 7.69% (1.260 versus 1.365; P < 0.001) relative to the ground-grain control diet.