British Poultry Science最新文献

1. The current study was conducted to determine the effect of dietary calcium pidolate (CalP) on performance, slaughtering characteristics, bone biomechanical properties, mineralisation and jejunum histomorphology in male broilers. A total of 200 one-day-old Ross 308 male chicks were randomly assigned to one of four treatments as five pen replicates, each containing 10 chicks. The basal diet without CalP was formulated to supply the nutritional needs of broilers and the treatment diets contained 0.30, 0.45 and 0.60 g/kg CalP, with limestone meeting the remaining calcium requirement.2. The addition of CalP had a quadratic effect on performance (P < 0.05) and the best performance was achieved in the group that included CalP at a dose of 0.45 g/kg but 0.60 g/kg level worsened performance. Supplementing with CalP linearly decreased carcass yield (P < 0.01) and relative breast weight (P ≤ 0.05) but the relative thigh weight increased quadratically (P < 0.05) and reached a maximum at 0.45 g/kg.3. Tibia shear force and stress linearly increased with the use of CalP in the diet (P < 0.05). Supplementation had a quadratic effect on tibial calcium (P < 0.01), reaching a maximum at 0.30 g/kg, although tibial phosphorus levels decreased linearly (P < 0.01).4. The effect of CalP on jejunum histomorphology fluctuated and, compared to the unsupplemented control group, the villus height/crypt depth ratio increased, while the other variables decreased (P < 0.05). Decrease in crypt depth with the addition of CalP was significant (P < 0.05).5. Using Ca-pidolate at a rate of 0.45 g/kg in broiler diets is sufficient to increase performance and tibia strength but 0.60 g/kg level negatively affected performance. In addition, the results of jejunum histomorphology were variable, but the crypt depth decreased with CalP levels and this is an important effect. However, further research is needed to detail the effect of CalP on broilers.

1. Shifting to higher welfare systems is expected to increase their environmental impact and mitigation strategies need to be identified. The environmental impacts associated with various broiler production systems (BPS: conventional, higher welfare indoors, free-range or organic) and the characteristics of BPS which contribute to these impacts were investigated via a literature review and meta-analysis.2. The impact metrics considered were global warming (GWP), acidification and eutrophication potentials, NH₃ emissions, land use, water use, energy use (EU) and biodiversity. Due to the paucity of data, analysis was limited to the impacts of the characteristics of the BPS: stocking density (STD), slaughter weight (SW), feed conversion ratio (FCR), on GWP, NH₃ emissions and EU.3. After correction for system boundaries and functional units, no statistical effects of BPS on GWP were found, while higher welfare systems were associated with higher EU. Reduced STD was associated with reductions in GWP and EU. The SW was positively associated with GWP and NH₃ emissions, while higher FCR was associated with increased NH₃ emissions and EU.4. Environmental impacts arose from feed-associated activities (>75%). Most of the GWP impacts were associated with land use change (LUC), especially when associated with 'unsustainable' soya. High variation in values for different environmental metrics within BPS indicated a lack of standardisation in the assessment of environmental impact across the industry.5. The results suggested that practices within a system contributed greatly to the environmental impact of the system. Rather than comparing systems, it may be more productive to focus on improving practices that have the potential to reduce environmental impacts within a system, without compromising animal welfare.

1. This study assessed the addition of dried stinging nettle (SN) leaves at 0%, 2.5% and 5.0% in feed on egg production, egg quality, chemical composition and antioxidant content in eggs from laying hens.2. Seventy-two Hy-Line Brown laying hens, housed in 36 enriched layer cages, were used in the study from 43 to 47 weeks of age. Feeding dry SN leaves did not affect (p > 0.05) egg production variables.3. Dietary SN inclusion linearly increased (p < 0.001) carotenoid content more than six-fold, in addition to yellowness and redness of the yolks at the maximum inclusion. Providing eggs from hens fed carotenoid enriched diets, e.g. SN, may be used to increase carotenoids in human diets.

1. This study investigated the role of glutathione peroxidase 4 (GPX4), a key regulator of ferroptosis, a form of programmed cell death, in muscle biochemistry and meat quality, utilising broiler chickens whose ante-mortem GPX4 activity was inhibited pharmacologically.2. Male broilers were divided into two groups, each receiving ante-mortem administration of the GPX4 inhibitor, Ras-selective lethal 3 (RSL3), or a vehicle only. After slaughter, breast muscles were collected and stored for 48 h. The expressions of ferroptosis-related genes, glutathione levels, pH, colour and water-holding capacity were evaluated at multiple time points during the storage period.3. The RSL3 treatment decreased the expression of GPX4 and ferritin heavy chain 1, which are negative regulators of ferroptosis, while it increased the expression of a ferroptosis accelerator, acyl-CoA synthetase long chain family member 4. The ratio of reduced to oxidised glutathione was significantly decreased in the RSL3 group. The RSL3 treatment decelerated post-mortem pH decline and colour changes, such as a decrease in L* and an increase in a* were observed in the RSL3 group. In addition, the RSL3 group showed increased levels of water-holding capacity.4. These findings suggested that ante-mortem GPX4 activity plays a role in determining meat quality, implying the possible involvement of ferroptosis in the mechanism by which skeletal muscle is converted after slaughter into meat that is eaten.

1. The objective of this research was to compare the pharmacokinetics and bioavailability of tolfenamic acid, analgesic, antipyretic and anti-inflammatory compound, after administration through different routes to Pekin ducks. The investigation was carried out over four time periods using a randomised cross-pharmacokinetic design.2. Tolfenamic acid was administered to ducks intravenously, intramuscularly, subcutaneously and orally at a dose of 2 mg/kg. Tolfenamic acid analysis was performed using HPLC-UV and pharmacokinetic data were conducted by non-compartmental analysis.3. The total clearance, volume of distribution at steady state and terminal elimination half-life after intravenous administration were 0.14 l/h/kg, 0.29 l/kg and 1.80 h, respectively. The peak plasma concentration and bioavailability for intramuscular, subcutaneous and oral administration were 4.59, 3.55 and 2.23 μg/ml and 93.62, 74.30 and 43.43%, respectively.4. Tolfenamic acid was absorbed rapidly, eliminated quickly and exhibited a small distribution volume in Pekin ducks. Pharmacokinetic parameters, including maximum concentration, area under the plasma concentration - time curve and bioavailability, were found to be different in ducks from other bird species.

1. The objective of the trial was to study the single and interactive effects of feed particle size in pelleted feed, dietary calcium (Ca) concentration and microbial phytase supplementation in broiler chickens. The studied traits were myo-inositol (1,2,3,4,5,6) hexakis (dihydrogen phosphate) (InsP₆) degradation, pre-caecal digestibility of phosphorus (P), Ca and amino acids (AA) and retention of P, Ca and nitrogen (N).2. Male Ross 308 broiler chickens were housed in metabolism units in groups of 10 and allocated to one of eight diets with seven pen replicates per diet. The 2 × 2 × 2-factorial arrangement included coarse and fine feed particle size (309 or 222 µm), low and high Ca concentration (4.9 and 7.2 g/kg) and without or with phytase supplementation (1,000 FTU/kg).3. Pre-caecal InsP₆ disappearance was higher with coarse than fine feed particle size when no phytase was added (54 vs. 48%) but not when phytase was added (74%; p = 0.046). High dietary Ca feeds decreased pre-caecal InsP₆ disappearance (67 to 59%) and P digestibility (65 to 55%; p < 0.001). Gizzard pH was lower with coarse than fine feed particle size and higher with high Ca than low Ca (p < 0.001). Pre-caecal digestibility of most AA was approximately 3.5%-points lower with high Ca without phytase compared to the other treatments (p ≤ 0.047). Coarse feed particle size caused higher pre-caecal AA digestibility than fine particle size (~2%-points; p ≤ 0.031). InsP₆ disappearance in the crop increased at high Ca concentration when phytase was added (22 vs. 37%; p = 0.011).4. Coarser feed particle size in pellets increased gastrointestinal InsP₆ degradation and nutrient digestibility, likely owing to effects on the gizzard functions. Additional Ca supply exerted antinutritive effects that was not compensated for by using coarser feed particles.

1. Exposure to stress alters normal homoeostasis and, hence, the antioxidant defence system. The aim of this study was to examine the effect of acute cold temperature on the antioxidant defence system in hens.2. Hy-line grey commercial layers (80 40-week-old) were randomly assigned to one of eight groups.  In groups 1 to 5, hens were exposed to low temperature at -8.68°C (cool stressed) for 2, 4, 6, 8 and 10 h, respectively. In groups 6 and 7, post 10 h cool stressed, hens were quickly transferred to room at 21°C to recovery for 2 h and 4h, respectively. In treatment groups 6 and 7, post 10 h cool stressed, hens were quickly transferred to room at 21°C for 2 h and 4 h, respectively. Group 8 was the control, where hens were housed under regular condition at 21°C as controls.3. Antioxidant enzymes (T-AOC), superoxide dismutase (SOD), glutathione peroxidase (GPx) and malondialdehyde (MDA), in skeletal muscle, the kidney, liver and pancreas were measured. The transcription of avUCP and ANT mRNA was tested by RT-PCR.4. The T-AOC activity was increased in the skeletal muscle of hens cold stressed for 2, 4, 6, 8 and 10 h and the 2 h recovery groups compared with control hens (p < 0.05). The GPx activity was increased in the liver and skeletal muscle after cold stress 4 h and in the pancreas of cold stress 2 h compared with the control group (p < 0.05). Antioxidant SOD activity was increased in the kidney after cold stress 6 h and in the liver after cold stress 10 h compared to the control group (p < 0.05). Measured MDA activity was increased in the pancreas after 2 h cold stress (p < 0.05).5. UCP mRNA expression level was increased in the pectoral muscle for 2 h and 4 h recovery groups compared with the control hens (p < 0.05) and avian uncoupling protein (UPC), adenine nucleotide translocator (ANT) expression level was increased in the leg muscle of hens cold stress for 2, 6, 8 h and recovery 2 and 4 h.6. The observed changes in the antioxidant defence system were tissue specific. Increments in levels of ANT (leg muscle) and UCP (pectoral and leg muscle) mRNA expression may be involved in the regulation of thermogenesis in skeletal muscle.

1. Dietary electrolyte balance (DEB) has been used to minimise problems in broiler chickens raised in warm climates. However, there is a need to determine the most appropriate DEB levels in these animals2. This study evaluated the influence of five DEB levels (110, 175, 240, 305 and 370 mEq/kg) on water intake (WI), zootechnical performance (feed intake, weight gain and feed conversion ratio), tibiotarsus bone variables (fresh bone weight, dry bone weight, bone length, mineral matter, Seedor index and bone strength) and intestinal histomorphometry (villus height (VH) and width (VW), crypt height (CH) and width (CW), internal and external muscularis) on broilers in two developmental phases (1-21 and 22-42 d of age). Additionally, the haematological profile (blood count and serum biochemistry), carcass yield, cuts and abdominal fat were assessed.3. Applying 370 mEq/kg DEB increased WI, VW in the jejunum and ileum and number of haemocytes at 21 d, while WI and VW in the duodenum and ileum at 42 d. In contrast, 110 mEq/kg increased chlorine concentrations at 21 d and leukocyte and heterophil numbers at 42 d.4. In summary, the 370 mEq/kg level was the most appropriate for broiler homoeostasis raised under natural heat stress, as the best results were found on WI and VW variables. Therefore, this DEB level was recommended in broilers aged 21 or 42 d.

1. Two concurrent experiments were conducted to investigate the effect of using the crude protein (CP) value of supplemental amino acids (AA) in formulating reduced-crude protein (RCP) diets. The RCP diets formulated without accounting for CP values of supplemental AA (RCPN) or otherwise (RCPY) or a positive control (PC) diet were fed without (Experiment 1) or with (Experiment 2) phytase.2. Each experiment utilised 105 male broiler chicks. Birds were provided a common starter diet from d 0-7. On d 21, ileal digesta were collected from the distal half of the ileum. For mRNA expression analysis, tissues were collected from the mid-jejunum and the liver. Excreta grab samples were collected for analysis for N content.3. In Experiment 1, there was a stepwise decrease (p < 0.01) in weight gain and excreta N for birds receiving PC, RCPN and RCPY diets. The coefficients of ileal digestibility of His, Leu, Phe and Trp were greater (p < 0.05) in birds that received RCPY rather than the PC diets. The relative mRNA expression of CAT1 was greater (p < 0.05) for birds that received the PC diet.4. In Experiment 2, growth performance and excreta N were not different between the PC and RCPN diets, but weight gain, feed intake and excreta N were greater (p < 0.01) in birds receiving PC or RCPN diets. The coefficients of digestibility were greater (p < 0.01) in RCP than PC diets for Lys, Thr, Cys, Gly and Ser. The mRNA expression for S6kinase and PRKAβ2 was greater (p < 0.05) for birds fed RCPN compared to PC.5. In conclusion, accounting for the N content of supplemental AA during feed formulation for RCP diets will influence the effect of CP reduction on growth performance and ileal amino acid digestibility.

1. The present study assessed the effect of different antioxidants on the quality of chilled/frozen-thawed sperm of red-legged partridge.2. Sperm samples from 40 red-legged partridges were collected and extended 1:1 (v:v) with Lake and Ravie 84, supplemented with ascorbic acid or butylated hydroxytoluene (BHT) at 0, 0.2, 0.4, 0.8 mM and catalase (CAT) or superoxide dismutase (SOD) at 0, 100, 200 and 300 IU/ml. Ten sperm samples were used per concentration. Motility and viability were evaluated in fresh and after 6 h of chilling at 5°C or after freezing-thawing.3. For chilled sperm, the presence of ascorbic acid decreased viability and several motility variables; BHT 0.8 mM increased non-progressive motility (NPM, 26.7 ± 1.99 vs. 20.7 ± 2.12); CAT 200 IU/ml improved the rectilinear velocity (40.4 ± 4.63 μ/s vs. 29.9 ± 4.62 μ/s) and linear progression ratio (52.8 ± 3.11% vs. 45.4 ± 2.98%); SOD 100 IU/ml increased NPM (24.5 ± 1.21% vs. 19.3 ± 1.75%) and tended to improve total progressive motility (42.7 ± 3.33% vs. 33.2 ± 3.26%, p = 0.07). Using an extender supplemented with CAT 200 or SOD 100 did not improve the post-thawed sperm quality.4. The present work provides an advance in the optimisation of chilling and freezing protocols for red-legged partridge sperm.