1. Typical poultry feed formulation models have been developed for meeting the minimum specifications of the essential amino acids (EAAs), ignoring the importance of providing precise levels of the non-essential amino acids (NEAAs) that are required for maximum performance. Including true protein (TP) values in these models in relation to EAAs can most accurately account for the requirements of all amino acids (AAs) in the ration (essential, non-essential and excess EAAs).

2. Data from recent research reports on the digestible lysine (dLys) requirements for maximum weight gain and minimum feed conversion ratio (FCR) were compiled from the literature. dLys requirements and the TP contents of the feeds were recalculated based on common ingredient composition values. Broken-line linear (BLL) and broken-line quadratic (BLQ) models were fitted to the data and compared.

3. The dLys requirements of broilers (g/kg diet) for body weight gain (BWG) and FCR were found to increase linearly as a function of the true and crude protein contents of the diet. These relationships were not affected by either age or sex. As chickens aged, the dLys requirements decreased. However, the dLys requirement to TP ratio did not change with age for BWG or FCR.

4. For maximum BWG and minimum FCR, the dLys requirements were estimated from the prediction models to be 4.92% ± 0.51 and 5.58% ± 0.70 of the TP level of the diet, using the BLL models, respectively.

5. The good linear relationship between the dLys requirement and TP level allows the prediction of the variables from each other for use in feed formulation to represent the requirements of both EAAs and NEAAs.

6. The dietary dLys requirements were estimated to be lower using the BLL vs. the BLQ models.

7. TP was a better predictor of dLys requirements than crude protein (higher R² values).

1. A growth experiment was conducted to determine the effectiveness of liquid analogue, DL-2-hydroxy-4-(methylthio) butanoic acid (HMTBA), compared to powder DL-methionine (DLM), in commercial maize–soybean-meal broiler diets similar to those commonly used in China, on feed conversion ratio (FCR), growth performance and European Production Index (EPI) of broilers.

2. A 4 × 2 + 1 factorial arrangement of treatments was used in which HMTBA or DLM was fed at 4 concentrations (low, medium, high and very-high inclusion rates) of supplementation at 100% equivalence on an equimolar basis. Negative control diets were commercial starter, grower and finisher feeds with no added methionine. A total of 1008 commercial-type Arbor Acres 1-d-old chicks were randomly distributed into 9 groups, with 8 replicates of 14 (7 male + 7 female) birds per treatment.

3. The body weight gain of the control group was significantly lower than that of the others in the starter period but did not show any differences during the other periods. The FCR of the control group was higher than that of the others except for those with HMTBA in the grower period. It was also observed that the FCR dropped as the supplemented concentration of methionine was increased regardless of the source. Some of the treatment groups produced a better breast yield than the control. The EPI between the two products did not show any significant difference.

4. In conclusion, both of the methionine sources were equally effective in ameliorating the effects of a dietary deficiency of total sulphur amino acids.

1. The present study was conducted to evaluate the role of extruded flaxseed (EFS) and α-tocopherol acetate (ATA) for the enhancement of polyunsaturated fatty acids ratio (PUFA) over saturated fatty acids (SFA) in broiler meat as a source of healthier meat.

2. A total of 96 one-d-old Cobb 550 broilers were randomly divided into 8 treatments with three replicates having 4 birds in each. EFS (extruded at 155°C) at 100, 150 and 200 g/kg alone and in combination with ATA at 200 mg/kg were supplemented through normal feed from the third week onward.

3. During the 6-week growth period, body weight gain (BWG), feed intake (FI), feed conversion ratio (FCR) and mortality were recorded. At slaughter, weight of liver, heart and kidney and fat content in breast and leg meat were measured. Fatty acid profiles in breast and leg meat were developed to estimate the PUFA to SFA ratio.

4. The results revealed that FI and FCR changed significantly in all groups and BWG increased in all the supplemented groups. The weight of liver, kidney and heart increased more in the supplemented group containing the maximum level of EFS with ATA compared with single supplementation of EFS.

5. The fat content in breast and leg meat decreased as the inclusion level of EFS increased. The level was low in leg meat compared with breast meat. Mortality decreased in all supplemented groups.

6. The PUFA to SFA ratio was significantly higher in leg meat (3.23) compared with breast meat (1.81) and the study therefore indicates that ATA and EFS supplementation could be used to improve the PUFA to SFA ratio in broiler meat.

1. The aim of this study was to investigate the use of indigenous lactic acid bacteria (LAB) with specific additives as a Biopreservation System (BS) for poultry blood during its storage in slaughterhouses.

2. The BS consisted of two LAB (Enterococcus faecalis DSPV 008SA or Lactobacillus salivarius DSPV 032SA) with 4 additives (lactose 2 g/l, yeast extract 0.4 g/l, ammonium citrate 0.4 g/l and NaCl 1 g/l). After 24 h storage at 30ºC, lower counts of enterobacteria, coliforms, Pseudomonas spp. and Staphylococcus aureus were evident in blood treated with the BS than in untreated blood.

3. The ability of LAB to prevent haemolysis was evident. A decrease in pH was associated with control of spoilage microorganisms but it needed to be regulated to prevent coagulation of proteins.

4. On the basis of these results it is recommended to supplement blood with a BS to avoid undesirable changes during blood storage before processing.

1. The aim of this study was to determine the mineral and lipid profiles in ostrich, turkey and broiler chicken livers.

2. The highest concentrations of phosphorus, potassium and magnesium were found in turkey livers, at 3751.50, 2153.05 and 363.98 mg/kg fresh weight (FW), respectively, whereas ostrich livers were the richest in calcium (82.77 mg/kg FW).

3. Ostrich liver was the richest source of iron, calcium, zinc and silicon, at 947.8, 82.77, 47.50, 36.69 mg/kg FW, respectively.

4. Ostrich livers proved to be the richest source of long-chain fatty acids (5.18% C20:4n+6, 0.48% EPA and 1.08% DHA)

1. The aim of the study was to evaluate the feasibility of replacing soybean meal (SBM) with Tenebrio molitor larvae (TML) meal in broiler diets.

2. A total of 80 30-d-old male Shaver brown broilers were divided into two groups fed on two isoproteic and isoenergetic diets differing for protein source (SBM vs. TML).

3. Up to 62 d of age, body weight and feed intake were recorded weekly and body weight gain, feed conversion ratio (FCR), protein efficiency ratio (PER) and European efficiency factor (EEF) were calculated. At 62 d, blood samples were collected from 16 birds/group for evaluation of blood profiles.

4. Feed intake was not different between groups considering the entire period of the trial. The FCR was more favourable in the TML than SBM group from 46 d of age and in the entire period of the trial (4.13 vs. 3.62). The PER was higher in the SBM than in the TML group (1.92 vs. 1.37) while the EEF was higher in broilers fed on the TML diet (132.6 vs. 156.2).

5. Albumin-to-globulin ratio was higher in broilers fed on SBM than in the other group (0.44 vs. 0.30). aspartate aminotransferase and alanine aminotransferase were higher in TML than SBM (195.1 vs. 178.6 U/l and 82.07 vs. 46.71 U/l, respectively). Uric acid was higher in broilers fed on SBM than TML (5.40 vs. 4.16 mg/dl).

6. TML did not affect feed intake and growth rate of broilers from 30 to 62 d of age when compared to an isoproteic and isoenergetic SBM diet, but FCR of the TML group was more favourable than that of the SBM group. The lowest albumin-to-globulin ratio in broilers fed on TML suggests a higher immune response, probably due to the prebiotic effects of chitin.

1. In this study, 6 dietary DL-methionine (Met) levels (2.5, 3.0, 3.5, 4.0, 4.5 and 5.0?g/kg) were tested to estimate the dietary Met requirements of Longyan ducks from 19 to 46 weeks of age, and to investigate its effect on the glutathione redox system.

2. In total, 1080 Longyan ducks aged 19 weeks were allocated randomly to the 6 dietary treatments, where each treatment comprised 6 replicate pens with 30 ducks per pen.

3. Met had no effects on egg production, yolk weight, yolk colour or the glutathione redox system, but the egg weight, egg mass and feed conversion ratio (FCR) were improved significantly by dietary Met supplementation. As the dietary Met concentration increased, the eggshell thickness and breaking strength decreased significantly, whereas the albumen weight increased significantly.

4. According to broken-line regression analysis, the optimum Met requirements for egg weight, egg mass, FCR and albumen weight are 686, 661, 658 and 731 mg/bird/d, respectively, with a dietary crude protein level of 170 g/kg.

1. Genetic parameters were determined for the worm burden of the most common gastro-intestinal nematodes in two chicken genotypes after being exposed to free-range farming conditions for a laying period.

2. Seventeen-week-old hens of 2 brown genotypes, Lohmann Brown (LB) plus (n = 230) and LB classic (n = 230), were reared for a laying period and subjected to post-mortem parasitological examinations at 79 weeks (LB plus) or 88 weeks (LB classic) of age.

3. There was no significant difference in faecal egg counts between the genotypes. Almost all hens (>99%) were infected with at least one nematode species. Species-specific nematode prevalence ranged from 85.8% to 99.1% between the two genotypes. Heterakis gallinarum was the most prevalent nematode (98.5%), followed by Ascaridia galli (96.2%) and Capillaria spp. (86.1%). Capillaria spp. were composed of C. obsignata (79%), C. caudinflata (16%) and C. bursata (5%).

4. All phenotypic and genetic correlations among worm counts of different parasite species were positive in combined genotypes (r_P ranged from 0.05 to 0.30 and r_G ranged from 0.29 to 0.88). A strong genetic correlation (r_G = 0.88 ± 0.34) between counts of A. galli and H. gallinarum was quantified. Heritability for total worm burden for LB plus and LB classic, respectively, were 0.55 ± 0.18 and 0.55 ± 0.34. Across both genotypes, the heritability of total worm burden was 0.56 ± 0.16.

5. In conclusion, there is a high variation attributable to genetic background of chickens in their responses to naturally acquired nematode infections. The high positive genetic correlation between counts of closely related worm species (e.g. A. galli and H. gallinarum) may indicate existence of similar genetically determined mechanism(s) in chickens for controlling these nematodes.

1. Two trials were conducted from 22 to 42 d post-hatch to evaluate the effectiveness of high concentrations of supplemental phytase in maize–soya bean meal-based diets severely limited in available phosphorus (P). Growth performance, plasma P and tibia ash (TA) were measured.

2. Each trial used 220 21-d-old male broilers in 20 pens with 11 birds per pen. Dietary treatments included a positive control [PC, 4.3 g/kg nonphytate P (NPP)], negative control [NC, 2.3 g/kg NPP (Trial 1) or 1.4 g/kg NPP (Trial 2)] and NC plus 1000, 2000 or 4000 phytase U/kg of the diet.

3. Birds fed on the PC diet had higher average daily gain (ADG), gain to feed ratio (G:F), plasma P (Trials 1 and 2) and TA (Trial 2) than those fed on the NC.

4. In Trial 1, ADG and G:F values of the NC plus 1000, 2000 or 4000 phytase U/kg reached those of the PC. Plasma P values of the NC plus 2000 or 4000 phytase U/kg reached that of the PC. Although TA values of the NC, NC + 1000 or NC + 2000 reached that of the PC, TA of the NC + 4000 was more than that of the PC.

5. In Trial 2, ADG and G:F values of the NC plus 4000 phytase U/kg reached those of the PC; nevertheless, plasma P values of the NC diets did not come up to that of the PC. While TA values of the NC, NC + 1000 or NC + 2000 did not reach that of the PC, TA of the NC + 4000 was greater than that of the PC.

6. Results of this study showed that, in the diets with 2.3 and 1.4 g/kg NPP, respectively, 1000 and 4000 phytase U/kg can be sufficient to obtain a comparable performance in broilers to those given diets adequate in available P.

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.  相似文献   

1. The objective of this study was to investigate the effect of a monocomponent protease and dietary inclusion of canola meal (CM) and poultry by-product meal (PBM) on growth performance, carcass characteristics and blood metabolites of turkeys fed on low crude protein (CP) diets from 28 to 55 d post hatch.

2. Experimental treatments included control, maize–soybean meal diet including 258.3 g/kg CP; negative control 1 (NC1), maize–soybean meal diet with reduced CP (232.4 g/kg); NC2, control diet (CP, 258.3 g/kg) including CM (80 g/kg) and PBM (80 g/kg); NC3, maize–soybean meal diet with reduced CP (232.4 g/kg) including CM (80 g/kg) and PBM (80 g/kg). Also, the NC1 + P and NC3 + P diets were created by addition of protease enzyme (30 000 units/kg of diet) to the NC1 and NC3 diets, respectively.

3. The NC3 group had lower body weight gain (BWG) compared to those fed on the control diet, and no improvement with enzyme addition (NC3 + P) was achieved. The protease addition to the NC1 diet (NC1 + P) improved BWG to the level of the control diet. The NC1 group had higher feed conversion ratio (FCR) compared to the control and NC3 + P, but protease addition to the NC1 diet improved FCR.

4. Protease addition to the low CP diets resulted in higher nitrogen (N) retention than in the control and NC2 groups. Also, the NC1 + P and NC3 + P diets increased apparent ileal digestibility (AID) of CP compared to the control group.

5. It was concluded that addition of CM (up to 80 g/kg) and PBM (up to 80 g/kg) to turkey diets had no negative effect on growth performance from 28 to 55 d of age. The NC1 + P group achieved the BWG of the control group which was partially due to increases in N retention and AID of CP, but the NC3 + P group failed to recover the growth losses. This difference implies that the efficacy of the protease may depend upon the protein source in the ration.

1. An experiment was conducted to study the effects of dietary supplementation of water-soluble ionised or chelated mineral mixture on growth performance, nutrient digestibility, blood characteristics, relative organ weight, meat quality and excreta microflora in broilers.

2. A total of 408 Arbor Acres broilers (17 birds in 8 replicate pens) were randomly allocated into one of the following three treatments: (1) Control/basal diet (CON), (2) T1 (basal diet + 0.5% ionised mineral mixture solution, pH 3.0) and (3) T2 (basal diet + 0.5% chelated mineral mixture solution, pH 3.0).

3. The body weight gain was greater and feed conversion ratio was lower in broilers supplemented with ionised or chelated mineral liquid complex compared to CON during the grower and overall phase of the experiment.

4. No significant effect in the concentration of Ca and P in the blood was observed in birds supplemented with ionised or chelated mineral mixture solution. No adverse effects were observed in organ weight and meat quality with ionised or chelated mineral mixture supplementation.

5. Regarding intestinal microbiota counts there was a reduction of Escherichia coli counts in the small intestine in ionised mineral supplemented birds. In the large intestine, E. coli as well as Salmonella populations were reduced in ionised mineral supplemented birds.

6. In conclusion, ionised or chelated minerals have partial positive effects in improving growth performance and reducing pathogenic bacteria load in the gastro-intestinal tract.

1. The effects of dietary electrolyte balance (DEB) and electrolyte–betaine (El-Be) supplements on heat-stressed broiler performance, acid–base balance and water retention were evaluated during the period 31–40 d of age in a 2 × 3 factorial arrangement of treatments.

2. A total of 240 broilers were assigned to 6 treatment groups each with 8 replicates of 5 birds per cage and were exposed to cyclic high temperature (32 – 24 ± 1°C). Birds were provided with diets having DEB of either 180 or 220 mEq/kg. El-Be supplements were either added to the diet, water or not added to either of them to complete the array of 6 treatment groups.

3. An additional 80 birds were kept at thermoneutral temperature (20 ± 1°C) and were provided with tap water and diets with DEB of either 180 or 220 mEq/kg to serve as negative controls.

4. Exposure to high temperature depressed growth performance, increased rectal temperature and decreased potassium (K⁺) retention. In high-temperature room, birds fed on diets with DEB of 220 mEq/kg tended to increase BW from 35–40 d of age. However, at thermoneutral temperature, broilers fed on diets with DEB of 220 mEq/kg increased K⁺ retention.

5. Adding El-Be supplements in feed or water improved feed conversion ratio (FCR), enhanced water consumption and increased K⁺ and sodium (Na⁺) retention.

6. Interactions between DEB and El-Be supplements tended to affect body weight gain and FCR during the periods 35–40 and 31–40 d of age, respectively. It is suggested that when using a diet with DEB of 180 mEq/kg, adding the El-Be supplements in drinking water was more beneficial than in feed. Adding the supplements in feed or water was equally useful when using DEB of 220 mEq/kg.

1. Two experiments were carried out in parallel with male Ross 308 broilers over 37 d. An experiment with a total of 736 broilers was performed to study the effect of dietary inclusion of crimped kernel maize silage (CKMS) on broiler production and meat quality. Another study with 32 broilers was carried out from 21 to 25 d to investigate the inclusion of CKMS on nutrient digestibility.

2. In both trials, 4 dietary treatments were used: wheat-based feed (WBF), maize-based feed (MBF), maize-based feed supplemented with 15% CKMS (CKMS-15) and maize-based feed supplemented with 30% CKMS (CKMS-30).

3. Compared with MBF, the dry matter (DM) intakes of broilers receiving CKMS-15 and CKMS-30, respectively, were numerically 7.5 and 6.2% higher and feed conversion ratio 6 and 12% poorer (significant for 30% CKMS), although there were no significant differences in AME content between the three diets. At 37 d, the body weight of birds receiving 15% CKMS was similar to birds fed with MBF. However, the inclusion of 30% CKMS decreased broiler growth. Dietary supplementation with CKMS significantly reduced the apparent digestibility of phosphorus. The fat digestibility was significantly lower for CKMS-30 than for the other three diets.

4. Broiler mortality decreased significantly when CKMS was added to the diet.

5. The consumption of drinking water was significantly lower in all maize-based diets as compared to WBF and was lowest in broilers fed with CKMS-30.

6. An improved litter quality in terms of DM content and a lower frequency of foot pad lesions was observed with broilers supplemented with both dietary levels of CKMS.

7. The addition of CKMS to maize-based diets increased juiciness, tenderness and crumbliness of the meat.

8. In conclusion, the dietary supplementation of 15% CKMS had no negative effect on broiler growth and positively influenced bird welfare in terms of mortality and foot pad health. Therefore, the addition of 15% CKMS to maize-based diets is considered an advantageous feeding strategy in broiler production.

1. A 42-d trial was conducted to investigate the effect of adding a synbiotic supplement to diets containing two different types of fat on performance, blood lipids and fatty acid (FA) composition and oxidative stability of breast and thigh meat in broilers.

2. A total of 800 one-d-old male broiler chickens were randomly assigned into 1 of 8 treatments with 4 replicates of 25 birds per treatment. The experiment consisted of a 4 × 2 factorial arrangement of treatments including 4 concentrations of synbiotic (0, 0.5, 1 or 1.5 g/kg diet) and 2 types of fat [sunflower oil (SO) or canola oil (CO)] at an inclusion rate of 50 g/kg diet.

3. Dietary fat type did not affect body weight gain (BWG) or feed conversion ratio (FCR) during the overall experimental period (0–42 d). However, fat type modified serum lipid profile and FA composition and 2-thiobarbituric acid-reactive substances (TBARS) content in breast and thigh meat.

4. The addition of synbiotic to the diet linearly improved overall BWG and FCR and also decreased serum cholesterol and low-density lipoprotein cholesterol concentrations. The TBARS value in thigh meat after 30 d of storage at 4°C was linearly decreased as the synbiotic inclusion concentrations in the diets increased. Dietary synbiotic also decreased the proportion of monounsaturated fatty acids and increased n-6 polyunsaturated fatty acid (PUFA) concentration in thigh meat, whereas the FA profile of breast meat was not affected by synbiotic supplementation. Moreover, the PUFA/SFA ratio in the breast meat was linearly increased when synbiotic was included in the CO-containing diets.

5. In conclusion, the addition of synbiotic to broiler diets had a positive effect on growth performance, blood lipid profile and meat quality. The results also support the use of synbiotic to increase the capacity of canola oil for enhancing PUFA/SFA ratio of breast meat in broilers.

1. The diet of broiler chickens supplemented with increasing concentrations of copper (Cu) was assessed for the effect of Cu on liver mitochondrial function.

2. A total of 160, 1-d-old Cobb 500 broilers (Gallus domesticus) were randomly assigned in equal numbers into 4 groups, which differed in the concentration of copper supplements in the diet; 11 (control), 110, 220 and 330 mg of Cu/kg dry matter. Liver mitochondrial function was recorded at 12, 24, 36, 48 and 60 d of age.

3. Supplementation with 110 mg Cu/kg dry matter enhanced mitochondrial function and activities of complexes I–V, and this was significant at 36 d of age compared with the other diets (P < 0.05). Supplementation with 220 mg Cu/kg dry matter and 330 mg Cu/kg dry matter enhanced mitochondrial function and activities of complexes I–V at 12, 24 and 36 d of age, but displayed reduced function (P < 0.05) at 48 and 60 d of age except in complex IV (P > 0.05). Mitochondrial hydrogen peroxide (H₂O₂) production was also increased (P < 0.05) with an increase of copper supplementation in the diet.

4. The results indicate that appropriate dietary copper supplements are sufficient for improving mitochondrial function and activities of the respiratory complexes. Higher concentrations of copper, on the other hand, lead to copper toxicity by affecting certain respiratory complexes.

1. The aim of this study was to determine the antibiotic susceptibility of 93 Lactobacillus strains isolated from domestic geese raised on Polish farms. The minimal inhibitory concentration (MIC) of 13 antimicrobial substances was determined by the broth microdilution method.

2. All strains were sensitive to the cell wall inhibitors ampicillin and amoxicillin (MIC ≤ 8 μg/ml). Resistance to inhibitors of protein synthesis and to fluoroquinolone inhibitors of replication was found in 44.1% and 60.2% of isolates, respectively; 26.9% strains were resistant to neomycin (MIC ≥ 64 μg/ml), 23.6% to tetracycline (MIC ≥ 32 μg/ml), 15% to lincomycin (MIC ≥ 64 μg/ml), 18.3% to doxycycline (MIC ≥ 32 μg/ml), 9.7% to tylosin (MIC ≥ 32 μg/ml), 56% to flumequine (MIC ≥ 256 μg/ml) and 22.6% to enrofloxacin (MIC ≥ 64 μg/ml).

3. Bimodal distribution of MICs indicative of acquired resistance and unimodal distribution of the high MIC values indicative of intrinsic resistance were correlated with Lactobacillus species. Eleven (11.8%) strains displayed multiple resistance for at least three classes of antibiotics.

4. Data derived from this study can be used as a basis for reviewing current microbiological breakpoints for categorisation of susceptible and resistant strains of Lactobacillus genus and help to assess the hazards associated with the occurrence of drug resistance among natural intestinal microflora.

1. A total 120 laying hens (60 TETRA BLANCA white egg layers and 60 TETRA SL brown egg layers) were selected from 250 TETRA BLANCA and 250 TETRA SL pullets based on their predicted body fat content by means of computed tomography (CT) at 16 weeks of age. Three groups of pullets were chosen for the investigation with the highest (n = 20), lowest (n = 20) and average (n = 20) body fat content.

2. Changes in the live weight, body fat content, egg production and egg composition of the chosen animals were recorded at 32, 52 and 72 weeks of age.

3. Based on the results, it was established that differences in starting body fat content of the hens remained the same during the experimental period. The differences between the two extreme groups were statistically significant at each age.

4. The starting body fat content of the hens affected the rate of egg production, i.e. hens with high starting body fat content produced 11–14 eggs fewer than the hens with a low or average body fat content but had no effect on the composition of the eggs.

5. Genotype affected almost all of the examined traits: TETRA BLANCA hens had lower live weight and higher body fat content during the experimental period and produced fewer eggs with lower albumen and higher yolk, dry matter and crude fat content than the TETRA SL hens.

1. The effects of different dietary energy concentrations on ostrich production variables were examined in two separate trials. The first trial tracked changes in production variables from the pre-starter phase through the starter phase and grower phase. The second trial was based on the finisher phase per se. In both trials, the influence of dietary energy on feed intake, feed conversion ratio (FCR) and growth variables was investigated. Additionally, basic abattoir weights were recorded, and measurements of the feathers and skin were performed.

2. In both trials, three diets with different concentrations of dietary energy were given during each phase where the low-, medium- and high-energy concentrations for each phase were as follows: 13.5, 14.5 and 15.5 MJ ME/kg feed pre-starter; 12.5, 13.5 and 14.5 MJ ME/kg feed starter; 10.5, 11.5 and 12.5 MJ ME/kg feed grower and 9.5, 10.5 and 11.5 MJ ME/kg feed finisher. Feed and water were available ad libitum in both trials.

3. Overall, it was found that the best performance for growth, FCR, skin size and grade, live weight, carcass weight and thigh weight were obtained on the medium-energy diet during the pre-starter, starter and grower phases.

4. During the finisher phase, improved growth rate and tanned skin size was found in birds given the diet with the highest energy concentration (11.5 MJ ME/kg feed). Carcass weight, growth rate and certain feather variables were also significantly influenced by gender.