Effect of intermittent feeding,structural components and phytase on performance and behaviour of broiler chickens

1. Two experiments were conducted to study the effect of intermittent feeding on performance and the efficacy of an exogenous phytase, and to assess whether intermittent feeding changed the activity pattern of broiler chickens.

2. Broiler chickens were given, either ad libitum or intermittently, a phosphorus deficient pelleted diet containing either coarsely or finely ground oat hulls and either no enzyme or a phytase added from 10 d of age, in a 2 × 2 × 2 factorial arrangement. Ad libitum feeding consisted of continuous access to feed in a room with 18 h of light and 6 h of complete darkness, whereas birds on intermittent feeding had restricted access to feed from 7 d of age, with 4 1-h feeding bouts/d and one 2-h feeding bout/d from d 14.

3. Performance, characteristics of the anterior digestive tract and phosphorus retention were assessed in experiment 1, while in experiment 2, birds were observed during 4-h periods to quantify different behaviours.

4. Intermittent feeding and phytase improved performance, but intermittent feeding did not improve the efficacy of the enzyme added. Ad libitum fed broiler chickens ate and drank on average twice per hour, and spent close to three-quarters of their time resting. Apart from an increased standing and feed searching activity for intermittently fed birds compared to ad libitum fed birds during the last hour before feed was presented, no differences in activity was detected.

5. It was concluded that broiler chickens quickly adapt to intermittent feeding without reduction in final body weight and with improvements in feed efficiency, but without improving the efficacy of dietary phytase. Only small changes occur in the behaviour of intermittently fed birds compared to ad libitum fed birds.     

Increased iron level in phytase-supplemented diets reduces performance and nutrient utilisation in broiler chickens

1. The effect of different levels of dietary iron on phytase activity and its subsequent effect on broiler performance were investigated in a 3 × 2 factorial arrangement. A total of 360 day-old Ross 308 male broiler chicks were distributed to 6 experimental diets, formulated with three levels of Fe (60, 80 and 100 mg/kg) and two levels of phytase (0 and 500 FTU/kg).

2. Phytase supplemented to mid-Fe diets increased feed consumption more than the non-supplemented diet at d 24. From hatch to d 35, Fe × phytase interaction significantly influenced the feed intake (FI), body weight gain (BWG) and feed conversion ratio (FCR). The high-Fe diet supplemented with phytase significantly reduced FI and BWG of broilers than those supplemented with low- or mid-Fe diets. The overall FCR was significantly better in birds fed on the mid-Fe diets with phytase supplementation.

3. A significant improvement in ileal digestibility of N, P, Mg and Fe was observed in birds feed diets containing 60 mg Fe/kg, with significant interaction between Fe and phytase.

4. Phytase improved the bone breaking strength when supplemented to low- or mid-Fe diets, compared to the non-supplemented diets. There was a significant Fe × phytase interaction effect. Tibia Fe content was higher in birds fed on phytase-free diets with high Fe but the reverse was the case when phytase was added and their interaction was significant. High dietary Fe significantly increased the accumulation of Fe in liver.

5. Phytase improved Ca-Mg-ATPase, Ca-ATPase and Mg-ATPase activities in jejunum when supplemented to the diet containing 80 mg Fe/kg.

6. This study indicates that high (100 mg/kg) dietary Fe inhibited phytase efficacy and subsequently reduced the overall performance and nutrient utilisation of broilers.     

Response of broiler chickens to different levels of calcium,non-phytate phosphorus and phytase

1. Five hundred and seventy six-d old Ross 308 broiler chicks (6 cages per diet, 8 birds per cage in 3 × 2 × 2 factorial arrangement) were fed on maize–soybean meal-based diets containing three concentrations of Ca (6, 8 or 10 g/kg), two concentrations of non-phytate phosphorus (NPP) (3 or 4 g/kg) and two levels of exogenous microbial phytase (0 or 500 FTU/kg) from d 0 to 35.

2. Body weight (BW), feed intake (FI) and mortality records were collected. Two birds per replicate were killed at 24 d of age to obtain tibia samples.

3. Increasing Ca level significantly reduced the FI and body weight gain (BWG) between hatch and 10 and 24 d, especially with the phytase-supplemented diets. However, phytase supplementation of the diet containing 4 g NPP/kg improved the FI and BWG at d 10 and 24. At d 24, phytase supplementation improved feed conversion ratio (FCR) of birds that consumed diets containing high NPP. The overall FCR was better in birds offered the phytase-supplemented, medium-Ca diet.

4. There was a significant reduction in length, width and breaking strength of the tibia bone in birds fed on a diet with high Ca and low NPP. Phytase supplementation improved the tibia ash content and bone breaking strength of chicks fed on the diet containing 8 and 4 g/kg Ca and NPP, respectively. The Ca content of the tibia bone was low in birds fed on diets with 6 and 4 g/kg Ca and NPP, respectively, but this was counteracted by phytase supplementation.

5. Birds fed on diets with 4 g/kg NPP had the best carcass percentage and parts yield. Phytase supplementation to high-Ca diets significantly reduced the carcass yield of birds.

6. These results confirmed the detrimental effect of high dietary Ca on phytase activity and subsequent growth and bone development of birds, especially when NPP is in short supply.     

Effect of high-dose phytase and citric acid,alone or in combination,on growth performance of broilers given diets severely limited in available phosphorus

1. Two trials were conducted to evaluate the effect of high-dose phytase alone or in combination with citric acid (CA) in the diet severely limited in available phosphorus (P) on performance, plasma P and plasma Ca of broilers from 22 to 42 d of age.

2. In Trial 1, 297 21-d-old female chicks were placed into 27 pens and allocated to 9 maize-soybean meal-based dietary treatments, which were a positive control [PC, 4.23 g/kg non-phytate P (NPP)] and 8 negative control (NC, 1.35 g/kg NPP) groups consisting of two concentrations of CA (0 and 20 g/kg) and 4 concentrations of phytase (0, 1000, 2000 and 4000 U/kg) in a 2 × 4 factorial arrangement. In Trial 2, 192 21-d-old male chicks were placed into 24 pens and allocated to 6 wheat-canola meal-based dietary treatments, which were a PC (4.2 g/kg NPP), a NC (1.68 g/kg NPP) and 4 NC groups consisting of two concentrations of CA (0 and 20 g/kg) and two concentrations of phytase (2000 and 4000 U/kg) in a 2 × 2 factorial arrangement.

3. In both trials, birds fed on the PC had significantly higher average daily gain (ADG), average daily feed intake (ADFI), plasma P and lower feed conversion ratio (FCR) and plasma Ca than those of birds fed on the NC. CA supplementation significantly increased ADG and ADFI. There was a significant interaction between CA and phytase on plasma P where CA improved the effect of phytase on plasma P. In Trial 1, phytase addition improved ADG, ADFI, FCR and plasma Ca linearly.

4. Briefly, this research showed the interaction effect between CA and phytase on plasma P when broilers were fed on diets based on maize-soybean meal or wheat-canola meal. The results showed that CA supplementation lowered the concentration of phytase that is needed in low NPP diets to increase plasma P.     

Influence of a microbial phytase on the performance and the utilisation of energy,crude protein and fatty acids of young broilers fed on phosphorus-adequate maize- and wheat-based diets

1. The effects of microbial phytase on the performance and nutrient utilisation in broilers fed on phosphorus-adequate starter diets were examined in this study. The effect of phytase on the apparent ileal digestibility of fatty acids was of particular interest. Two grain types (maize and wheat) and two inclusion concentrations of a phytase enzyme from Escherichia coli expressed in Schizosaccaromyces pombe (0 or 500 phytase units (FTU)/kg of feed) were evaluated in a 2 × 2 factorial arrangement of treatments.

2. Supplemental phytase improved the weight gain and feed per gain, but had no effect on the feed intake of young broilers receiving phosphorus-adequate diets.

3. Phytase supplementation improved the apparent ileal digestibility of nitrogen and phosphorus in both diet types. Phytase supplementation tended to improve the apparent ileal digestible energy in wheat-based diets, but had no effect on the apparent metabolisable energy in both diet types.

4. Supplementation of phytase increased the apparent ileal digestibility of fat, with similar effects for the different fatty acids measured. Increments on ileal fat digestibility due to phytase were not dependent on the type of diet.

5. Dietary supplementation of microbial phytase enhanced not only the digestibility of phosphorus, but also that of nitrogen and fat, exhibiting increased ileal digestibility for all fatty acids in P-adequate maize- and wheat-based diets.     

Valine,isoleucine, arginine and glycine supplementation of low-protein diets for broiler chickens during the starter and grower phases

1. Two experiments were performed to study the supplementation of valine, isoleucine, arginine and glycine (Val, Ile, Arg, Gly) in low-protein diets for broiler chickens in the starter (1–21 d; Exp. 1) and grower (22–42 d; Exp. 2) phases.

2. A low-crude protein (CP) diet was formulated to meet the requirements of all amino acids (AA) supplied by the control diet except for Val, Ile, Arg and Gly. The other experimental diets were obtained by the isolated or combined supplementation of the studied AA in the low-CP diet.

3. Growth, serum parameters and litter characteristics were taken in both of the experiments. Carcass measurements were taken in Experiment 2.

4. In the starter and grower phases, low-CP diets without supplementation resulted in birds with a poorer weight gain and feed conversion than those of the birds that received the control diet.

5. In the starter phase, individual supplementation with Val and Gly, but not Ile and Arg, restored the weight gain of the birds, while diets with the addition of Val + Gly, Val + Ile + Arg, Val + Ile + Gly and Val + Ile + Arg + Gly restored their feed conversion.

6. In the grower phase, weight gain was re-established at the same rate as the control diet for the diets supplemented with Val + Ile, Val + Ile + Arg, Val + Ile + Gly and Val + Ile + Arg + Gly. However, the feed conversion was restored only in birds that received the diet supplemented with all studied AA.

7. The supplementation of Val and Gly in low-CP diets was sufficient to avoid adverse effects in the performance and serum parameters of broilers in the starter phase. However, birds in the grower phase required the combined supplementation of Val, Ile, Arg and Gly, to prevent compromised performance.     

Effect of two microbial phytases on mineral availability and retention and bone mineral density in low-phosphorus diets for broilers

1. The efficacy of supplementation of a low-phosphorus (low-P) maize–soyabean meal diet for broiler chickens with two different microbial (fungal and bacterial) phytases was examined.

2. Broiler chickens received a low-P maize–soyabean meal diet containing either no phytase or one of the two phytases included at one and two times the manufacturer's recommended inclusion level for 21 d.

3. Titanium dioxide was included in the diets as an indigestible marker. Excreta were collected quantitatively from d 18 to 21, and at the end of the study the birds were killed and ileal digesta and leg bone samples collected.

4. No differences were observed for body weight gain and feed intake or apparent metabolisable energy (AME) among all dietary treatment groups.

5. Dietary phytase supplementation improved the apparent retention of Ca, Na and Cu and ileal phytate P absorption from 32% to 44% across inclusion levels.

6. Bone mineral density (BMD) was improved for both phytases across inclusion levels by, on average, 9% for the tibia and 13% for the femur.

7. Dietary phytase supplementation of the low-P diet improved apparent ileal digestibility of serine, glycine, valine, isoleucine, tyrosine, histidine, lysine and arginine.

8. When the results from the present study were combined with the results from other similar published studies and analysed statistically, factors such as dietary P and Ca concentration, as well as bird breed and age, rather than the type or activity of microbial phytase, had the greatest impact on the extent to which dietary supplementation improved P and Ca retention.

9. More work is required to explain the interrelationships between the multiple factors influencing the efficacy of phytase on the availability of dietary minerals.     

Feed processing and structural components affect starch digestion dynamics in broiler chickens

1. A 2 × 2 factorial design was used to test the hypothesis that impaired intestinal starch digestibility is attributable to rapid passage of digesta from the gizzard to the intestine, and that, compared to steam pelleting, increasing the availability of starch through extrusion cooking may alleviate the potential negative effect of rapid digesta flow on starch utilisation.

2. Thus, 7-d-old-broiler chickens were distributed to 48 cages and given a wheat-based (WB) pelleted diet containing either coarse oat hulls (OH-Pel) or fine cellulose (Cel-Pel) until d 19 to stimulate divergent development of the gizzard. Thereafter, both groups were further subdivided and challenged with a WB diet containing cellulose in either pelleted (Cel-Pel) or extruded (Cel-Ext) form on d 20 and 22. Either excreta or intestinal contents were collected at time intervals after feeding and analysed for marker and starch.

3. OH-Pel increased gizzard size and holding capacity. No excessively high starch levels (maximum 25 g/kg) were detected in the excreta. However, 8 h feed-deprived birds given Cel-Pel and challenged with Cel-Pel exhibited higher starch excretion and showed large individual variation during the first 135 min of collection.

4. Contrary to the OH-Pel group, more digesta and starch passed to the jejunum at 1 and 2 h and ileum at 2 and 3 h after feeding for birds given Cel-Pel, resulting in lower jejunal and ileal starch digestibility.

5. Increased starch gelatinisation through extrusion processing significantly improved starch digestibility regardless of gizzard function. However, at 1, 2 and 3 h after feeding, more digesta was retained in the foregut of birds given Cel-Ext.

6. The current data showed that starch degradation rate is associated with the flow of digesta which is linked to gizzard development, and that enzymatic hydrolysis of intact starch granules may be limited with more rapid feed passage through the gut.     

Effects of evisceration and storage temperature on changes in meat quality of traditional farm‐fresh Turkeys

1. Conditions affecting the keeping quality of traditional farm‐fresh turkeys were investigated.

2. Storage of uneviscerated Wrolstad turkeys at 4 °C for 10 days caused no statistically significant changes in meat flavour or texture.

3. During further storage at —2 °C, however, there was a slight but significant change in flavour, which became more marked with time in birds which had been eviscerated after the initial period at 4 °C.

4. Both eviscerated and uneviscerated birds became slightly tougher during storage.

5. Initial holding at 4 °C increased the numbers of psychrotrophic bacteria on the skin by about 10³ but subsequent changes at — 2 °C were slight for uneviscerated birds.

6. Eviscerated carcases had higher counts than uneviscerated birds after storage at — 2 °C and, although ‘off’ odours were not detected, spoilage appeared to be imminent at the end of the 20‐d period.     

Fat accumulation,fatty acids and melting point changes in broiler chick abdominal fat as affected by time of dietary fat feeding and slaughter age

1. This work aims to quantify changes in fatty acid profile, melting point, abdominal fat accumulation and 2-thiobarbituric acid-reactive substances production depending on dietary fat source and age at slaughter, and to estimate the optimal date for the change from an unsaturated fat to a saturated fat diet or vice versa.

2. Treatments established were (1) birds fed 8% tallow from 21 to 49 d (TTT); (2) birds fed 8% tallow from 21 to 37 d and 8% sunflower oil from d 38 to 49 (TSS); (3) birds fed 8% sunflower oil from 21 to 37 d and 8% tallow from d 38 to 49 (STT); (4) birds fed 8% sunflower oil from 21 to 41 d and 8% tallow from d 42 to 49 (SST); (5) birds fed 8% sunflower oil from 21 to 49 d (SSS). Birds from each group were slaughtered on d 21, 29, 38, 40, 42, 44, 46 and 49.

3. The polyunsaturated fatty acids (PUFAs) proportion in the SSS group reached maximum values at d 40 and fitted a quadratic response. This group also showed a decrease in saturated fatty acids (SATs) and monounsaturated fatty acids (MUFAs) of lower intensity than the PUFA increase. The highest synthesis of SAT + MUFA was found in the SSS and TSS groups, whereas these had the lowest body-to-dietary PUFA ratio.

4. A high and quadratic increase in the MUFA proportion was observed during the first 10 d of feeding with the tallow-enriched diet at the expenses of the proportion of PUFA that quadratically decreased (minimum values at d 38).

5. Lipogenic and desaturation capacity decreased with age.

6. The TSS group increased tissue PUFA content faster that the SST group decreased PUFA content after the change in diet which indicates that the earlier feeding has to be taken into consideration for obtaining higher or lower changes in quality parameters.

7. The melting point of the SSS group showed a lower response to the dietary treatment in the initial period when compared to the TTT treatment.

8. The TTT, STT, SST and TSS groups showed similar fat accumulation, and changes in lipid oxidation were related to the day of dietary sunflower oil supplementation.

9. Based on the results, it would be possible to determine the most appropriate dietary programme and optimum slaughter age to obtain chicken meat with the desired quality characteristics.     

Evaluation of the potential killing performance of novel percussive and cervical dislocation tools in chicken cadavers

1. Four mechanical poultry killing devices; modified Armadillo (MARM), modified Rabbit Zinger (MZIN), modified pliers (MPLI) and a novel mechanical cervical dislocation (NMCD) gloved device, were assessed for their killing potential in the cadavers of euthanised birds.

2. A 4 × 4 × 4 factorial design (batch × device × bird type + age) was employed. Ten bird cadavers per bird type and age were tested with each of the 4 devices (N = 160 birds). All cadavers were examined post-mortem to establish the anatomical damage caused.

3. NMCD, MARM and MZIN demonstrated killing potential, as well as consistency in their anatomical effects. NMCD had the highest killing potential, with 100% of birds sustaining the required physical trauma to have caused rapid death.

4. The MPLI was inconsistent, and only performed optimally for 27.5% of birds. Severe crushing injury was seen in >50% of MPLI birds, suggesting that birds would die of asphyxia rather than cerebral ischaemia, a major welfare concern. As a result, the MPLI are not recommended as a humane on-farm killing device for chickens.

5. This experiment provides important data on the killing potential of untried novel percussive and mechanical cervical dislocation methods, informing future studies.     

Effects of dietary boron and phytase supplementation on growth performance and mineral profile of broiler chickens fed on diets adequate or deficient in calcium and phosphorus

1. Two experiments were designed to determine the effect of dietary boron (B) in broiler chickens. In Experiment 1, a 2 × 4 factorial arrangement of treatments was used to investigate the effect of dietary calcium (Ca) and available phosphorus (aP) (adequate or deficient) and supplemental B (0, 20, 40, and 60 mg/kg diet). In Experiment 2, B, at 20 mg/kg, and phytase (PHY) (500 FTU/kg diet) were incorporated into a basal diet deficient in Ca and aP, either alone or in combination.

2. The parameters that were measured were growth performance indices, serum biochemical activity as well as ash and mineral (i.e. Ca, P, Mg, Fe, Cu and Zn) content of tibia, breast muscle and liver.

3. Results indicated that both supplemental B and dietary Ca and aP had marginal effects on performance indices of chickens grown for 42 d.

4. There were positive correlations (linear effect) between B concentrations of serum, bone, breast muscle and liver and the amount of B consumed.

5. Serum T₃ and T₄ activities increased linearly with higher B supplementation.

6. Increasing supplemental B had significant implications on breast muscle and liver mineral composition. Lowering dietary Ca and aP level increased Cu content in liver and both Fe and Zn retention in breast muscle. Tibia ash content and mineral composition did not respond to dietary modifications with either Ca–aP or B.

7. The results also suggested that dietary contents of Ca and aP do not affect the response to B regarding tissue mineral profile. Dietary combination with B and PHY did not create a synergism with regard to growth performance and bioavailability of the minerals.     

Production traits of artificially and naturally hatched geese in intensive and free-range systems: I. Growth traits

1. This study investigated the effect of incubation type and production system on geese growth traits.

2. A total of 216 geese were either naturally (114) or artificially (102) hatched and reared in intensive or free-range production systems (4 replicates each) until 18 weeks of age.

3. Weights of naturally hatched goslings (NHG) were significantly higher than artificially hatched goslings (AHG) at 2 weeks (644 vs. 536 g); however, weights of AHG were significantly higher than NHG at both 6 weeks (3245 vs. 3010 g) and 18 weeks (5212 vs. 4353 g).

4. AHG had better feed conversion ratios (FCRs) than NHG (6.21 vs. 6.46 at 18 weeks). Feed consumption of naturally hatched geese was found higher in first 4 weeks when compared to artificially hatched geese and artificially hatched geese consumed more feed than naturally hatched geese after 8 weeks.

5. Production system had insignificant effects on feed consumption, FCRs, viability and mutilation rates.

6. Slipped wings were more frequent in NHG than AHG (8.32% vs. 1.68% at 6 weeks; 23.84% vs. 5.12% between 7 and 18 weeks) and in free-range production when compared to intensive production (17.88% vs. 11.08% over the course of the production period).

7. The study results indicate that both artificially and NHG can be reared in free-range production systems without any loss in performance and in deference to animal welfare.     

Improved early performance of turkey poults given an Aloe ferox leaf extract with bentonite

1. AT-402 (20 g/kg), a proprietary blend of Aloe ferox leaf extract and calcium bentonite, had no adverse effect on poult body weights at 3 weeks of age.

2. Lower body weights and lower feed consumption were observed in 4-week-old poults given 10 and 20 g/kg of AT-402 compared to poults given 0 or 5 g/kg.

3. Floor-reared poults, given either 5 or 10 g/kg AT-402 to 4 weeks of age, were significantly heavier than controls (0 g/kg AT-402), and feed conversion ratios for AT-402 given poults were improved.

4. Xylose uptake in 5 g/kg AT-402-fed poults was significantly greater than in poults given AT-402 at 0 and 10 g/kg, reflecting increased body weights of 5 g/kg AT-402-fed poults.

5. Delayed access by poults to the AT-402 until 10 d of age also improved 4-week body weights, suggesting that the AT-402 might improve performance as soon as it is given.

6. AT-402 at 5 g/kg was most efficacious as demonstrated by improved body weights and feed conversions.     

The effects of restricted feeding on adrenal cortical activity in the immature domestic fowl

1. The effect of reducing food intake to 75% of the ad libitum intake was determined from hatching to 8 weeks in young Light Sussex chickens.

2. Restricted birds were lighter throughout the experiment.

3. Relative adrenal weight tended to be greater in restricted birds but the difference decreased with time.

4. There was no depletion of adrenal cholesterol: from week 5 there was a significantly greater amount in the adrenals of restricted birds.

5. After 1 week of restriction plasma corticosterone concentration was 73% greater than in controls. It decreased progressively, falling within the normal range at 5 weeks.

6. Restricted birds were hypoglycaemic from weeks 2 to 7 and hyper‐lipacidaemic throughout. A negative correlation between plasma glucose and free fatty acids was found.     

Protein and energy metabolism in two lines of chickens selected for growth on high or low protein diets

1. Genetic adaptation was investigated in broilers selected for seven generations on a normal (A) or a low (B) protein diet.

2. Protein and energy metabolism were studied in males from these selected lines fed on a diet of intermediate protein content.

3. All selected birds retained more nitrogen than those studied 10 years previously.

4. There was no difference in nitrogen retention between groups, although relative growth rate of group B birds was higher.

5. Heat productions relative to gross energy intake were 0.38 (group B) and 045 (group A). Energy retentions relative to gross energy intake were 0.39 (group B) and 0.35 (group A); the difference being primarily due to higher fat retention in group B.

6. Using a common maintenance requirement for metabolisable energy, group B utilised metabolisable energy for growth (0.78) better than did group A (0.71).

7. At 53 d of age plasma glucose (10%) and insulin (50%) were higher in group B than in group A.     

Comparative study of the effects of organic selenium on hen performance and productivity of broiler breeders

1. A 10-week experiment was conducted with Ross 308 broiler breeder chickens in cages to evaluate the influence of organic and inorganic sources of selenium (Se) supplementation. A total of 600 birds at 29 weeks of age were divided at random into 4 groups and fed on a maize–soya basal diet supplemented with different forms of Se.

2. The first (control) group was given the basal diet without Se supplementation, whereas the second, third and fourth groups were given, respectively, the basal diet with 0.3 mg/kg of inorganic Se in the form of sodium selenite or 0.3 and 0.5 mg/kg of organic Se in the form of Se enriched yeast (Se-yeast).

3. The experiment was carried out for 10 weeks to compare and evaluate the influence of Se supplementation on breeder performance, egg production, hatchability and the quality of eggs. Samples were collected for analysis at weeks 0, 5 and 10 of the experimental period.

4. At the end of the experiment (39 weeks), there was a reduction in mortality in breeders given diets supplemented with 0.5 mg/kg of Se-yeast. Supplementation of feed with 0.5 mg/kg organic Se increased egg production, percentage of settable eggs and hatchability.

5. Selenium supplementation increased egg weight and specific gravity compared to the control diet. However, no significant variation was found in albumen or yolk protein content at the end of week 10.

6. Selenium accumulation and glutathione peroxidase (GSHPx) activity were lower in the egg albumen and yolk of control compared with Se-supplemented treatments. Se accumulation and GSHPx activity were higher in the group given 0.3 mg/kg organic compared to 0.3 mg/kg of inorganic Se.

7. The results favour the use of Se-yeast at the dose of 0.5 mg/kg in broiler breeder diets for better productivity of eggs, settable eggs, hatchability and higher Se accumulation and antioxidant status in eggs.     

Effect of substrate provision on performance and behaviour of laying hens in the pecking and scratching area of furnished cages

1. An experiment was set up to study the effects of substrate provision on performance and behaviour in the pecking and scratching area (PSA) of non-beak-trimmed hens housed in large furnished cages (60 hens/cage).

2. Three layer hybrids (two brown and one white, ISA-Hendrix Genetics, France) and two substrate conditions (with or without wheat bran automatically distributed on the PSA) were compared in a 3 × 2 experimental design with 12 cages per treatment.

3. Substrate distribution improved laying rate with no impact on the frequency of dirty or cracked eggs.

4. Substrate distribution improved the viability and body integrity of hens, which were not beak-trimmed.

5. Distribution of substrate tended to increase the number of hens in the PSA and enhanced their pecking and scratching behaviours but had a negative impact on the number of dust bath bouts per cage and encouraged dust bathing on the wire floor close to the feeder.

6. The white hens laid more eggs in the nest than the brown birds and used the PSA more for pecking, scratching and dust bathing at the end of the day than the brown hens, underlining the necessity to adapt cage furnishing and rearing management to specific behaviours of each layer genotype.     

Absorption and deposition of xanthophylls in broilers challenged with three dosages of Eimeria acervulina oocysts

1. An experiment was designed to evaluate the effect of different doses of oocysts of Eimeria acervulina on intestinal absorption and skin deposition of xanthophylls (XAs) in broilers.

2. A total of 192 broiler chickens were randomly assigned to 4 groups: an uninfected control group and three groups inoculated with either 1 × 10², 1 × 10⁴ or 1 × 10⁵ sporulated oocysts of E. acervulina by gavaging at 21 d. There were 4 replicate pens (2 male and 2 female) per group.

3. Plasma xanthophyll (PX) and skin yellowness (SY) were measured in live birds weekly. At 42 d of age, SY was measured in the breast and abdomen after chilling and in the breast 24 h post-processing on refrigerated carcasses.

4. In general, in all challenged treatments, and for the duration of the study, the average PX decreased by 0.02 μg/ml (R² = 61.6%) for every 1000 inoculated oocysts, whereas PX increased by 1.26 μg/ml/d in uninfected birds.

5. The average SY in live birds from 21 to 42 d of age decreased by 0.019 b*/every 1000 oocysts administered, while SY of uninfected controls increased by 0.57 b*/d. It was also noted that in all treatments females had a greater SY (6.17 b*) than males for the duration of the study. The SY of the breast and abdomen was correlated (r = 0.76) in chilled carcasses. Breast SY in 24 h refrigerated carcasses was greater in the control group and for female birds.

6. Oocyst excretion was different between inoculated treatments only on 7 d post-inoculation (PI). Coccidia lesion scores in the duodenum averaged 1+ in infected birds and 2+ in birds given the highest oocyst dose.     

Effects of caponisation and age on the histology of the internal organs of Leghorn cockerels

1. Poultry researchers seek the most efficient bird line to produce capons (castrated cockerels). The previous studies did not include results from histopathological analyses of internal organs after caponisation. No data have been published on whether adipose tissue accumulates in internal organs or if caponisation changes the structure of the lymphoid organs and the accumulation of lymphoid cells.

2. The aim of this study was to analyse the occurrence of histopathological lesions in internal organs from Leghorn (layer-type) capons and cockerels at different times of fattening.

3. Two hundred, one-day-old Leghorn cockerels were used in this experiment. At 8 weeks of age, the birds were randomly divided into a control group (100 uncastrated cockerels) and a second group consisting of 100 castrated birds. At 12, 16, 20, 24 and 28 weeks of age, six cockerels and six capons were slaughtered. Samples of all internal organs from six cockerels and six capons at each slaughter age were evaluated.

4. The main histopathological differences between capons and cockerels were related to the accumulation of adipose tissue, with higher values noted in capons, especially in the gizzard and the caecum submucosa and fatty degeneration in liver hepatocytes.

5. Additionally, differences were observed more often in cockerels than in capons with regard to depletion of lymphoid cells in lymphoid organs, including the thymus and bursa of Fabricius in 28-week-old birds and the spleen in 24-week-old birds.

6. These studies prove that caponisation causes the accumulation of fat in internal organs and changes the structure of lymphoid organs.

7. Age influences the occurrence of desirable lesions, such as the accumulation of adipose tissue within the examined organs, and older capons (24 and 28 weeks old) are better sources of high quality, potentially edible tissues.