Effects of variety, the 1B/1R translocation and xylanase supplementation on nutritive value of wheat for broilers.

1. Three consecutive studies were done with 12 wheat samples (4 per study), each of different variety (6 containing the 1B/1R rye translocation) to examine the effects of wheat variety, presence of 1B/1R and interactions with xylanase addition (Avizyme 1310). The wheat varieties covered a wide range of in vitro viscosity (6.3 to 19.8 cps). In each study 64 male, Ross broilers were individually caged and given the diets ad libitum from d 7 to 28. Bird performance, viscosity of ileal contents and diet metabolisability (AME) were measured. 2. The diets contained (g/kg): wheat 790, casein 134, dicalcium phosphate 21.4, potassium bicarbonate 10.8, sodium bicarbonate 7.5, soya oil 10, arginine 5, minerals etc. 21.3. 3. Within each study there were large differences in dry matter (DM) intake between varieties but the variety effect was significant (P<0.01) only in study 2. Liveweight gain (LWG) differences mirrored DM intake, being significant (P<0.01) in study 2. Mean gain:food was unaffected by variety in any study. 4. Calculated wheat AME (MJ/kg DM) ranged from 13.4 to 14.4 in study 2 (P<0.05), the values for studies 1 and 3 lying within this range. 5. Across all 3 studies, in vivo viscosity (proximal ileum) ranged from 5.0 to 37.6 in the absence of enzyme and from 3.9 to 12.1 with enzyme addition; in studies 1 and 2 variety differences were significant (P<0.05). 6. Enzyme addition had no effect on DM intake or LWG but gain:food tended to be improved (NS), metabolisability of energy (ME:GE) was increased (P<0.01) by 2.2% and calculated wheat AME by 4% while in vivo viscosity was reduced (P<0.001). 7. There were no significant differences in DM intake, LWG, gain:food, ME:GE or calculated wheat AME concentration associated with the presence of the 1B/1R translocation and no interactions between enzyme and 1B/1R. 8. There were poor relationships between either gain:food or wheat AME concentration and in vitro or in vivo viscosity. There was no significant relationship between AME concentration and either specific weight or thousand grain weight. 9. It was concluded that (a) variety differences tended to be small (b) there was no negative impact of the 1B/1R rye translocation with the diet formulation used (c) in vitro viscosity failed to predict satisfactorily any aspect of performance with the high wheat/low fat diet formulation used.     

Metabolisable energy content of diets and broiler performance as affected by wheat specific weight and enzyme supplementation

1. Two experiments were performed with male, Ross broiler chicks to study the relationship between wheat specific weight and performance parameters and the effects of xylanase inclusion in diets of different wheat specific weight (SW). 2. In both studies wheat was incorporated at 667 g/kg and a protein concentrate based on soyameal 50, full fat soyameal, extrupro and herring meal and formulated to provide (g/kg) crude protein 370, crude oil 140, crude fibre 45, crude ash 110 was incorporated at 333 g/kg. 3. In Experiment 1, 3 wheats (69, 67, 57, SW respectively) without or with enzyme (Avizyme TX, Finnfeeds International) and in Experiment 2, 6 wheats (81, 77, 76, 70, 64, 61 SW respectively) were used and diets were fed ad libitum to individually caged birds. 4. In Experiment 1 the feeding period was 7 to 28 d and a total excreta collection was made from 14 to 20 d for determination of apparent metabolisable energy (AME) content. Experiment 2 started at 4 d with excreta collections from d 6 to 9, 10 to 12 and 13 to 19 inclusive for AME measurements. 5. In Experiment 1 there were no significant effects of wheat on dry matter (DM) intake but liveweight gain (LWG) and gain:food were significantly better for 67 SW than for 57 SW. Food enzyme inclusion improved LWG and gain:food but there was a significant wheat/enzyme interaction for gain:food with no improvement due to enzyme addition for 67 SW but a 5% improvement for 57 SW. There was no significant effect of wheat or enzyme addition on the measured AME contents of the diets. 6. In Experiment 2, although not statistically significant, there were large numerical differences in food intake between diets, with the lowest values occurring for 64 SW. For the complete period, wheat variety tended to affect LWG (P=0.057) with the best and worst results recorded for the 2 low SW wheats. Gain:food was significantly affected by wheat, the poorest values occurring with 64 SW and the best with 77 SW Diet AME content was also affected by wheat variety (P<0.01) but the low result obtained for 61 SW was not mirrored in the gain:food value. The lack of correlation between diet AME values and gain:food could not be attributed to differences in protein or amino acid content of the diets. 7. In Experiment 2 diet AME content increased from period 1.1 (6 to 9 d) to period 2 (13 to 20 d) by 7% but interpretation is hampered by the short adaptation period (2 d) prior to period 1.1. The AME values obtained in both studies during the 3rd week of age were towards the upper end of the range of values in the literature. 8. In Experiment 2 there was a good correlation (r2=0.95) between SW and wheat starch content and between SW and calculated wheat AME content (r2=0.40, P<0.001) but a poor correlation between SW and gain:food. There was also a high correlation between wheat AME content and starch content (r2=0.41, P<0.001). Taken together with the results of Experiment 1 it appeared that starch content is a better measure of wheat quality than specific weight.     

Importance of amino-acid and electrolyte balance in experimental diets used to determine the apparent metabolisable energy (AME) value of wheat

1. An experiment was done with male, Ross broiler chicks to study the effect of diet composition and electrolyte balance on the measurement of diet AME and performance parameters in diets containing high levels of wheat inclusion. 2. The control diet (G) was based on wheat (667 g/kg) with full-fat soya, soyabean meal, Extrupro and herring meal providing the protein supplements. The experimental treatments were based on 2 diets, one based on wheat (790 g/kg) with casein as the protein supplement and the other containing 667 g/kg wheat plus casein, cellulose and starch. Each of these was formulated to contain one of three concentrations of sodium and potassium bicarbonate giving final values for dietary electrolyte balance of approximately 90, 180 and 280 meq/kg diet. 3. DM intake was numerically lower with the lower level of wheat inclusion and LWG (P < 0.05) and gain:food (P < 0.001) were reduced. ME:GE was similar for the two levels of wheat/casein but higher (P < 0.001) than for the control diet. 4. The two higher electrolyte balances improved DM intake (P < 0.01), LWG and gain:food (P < 0.01) compared with the diets containing no added bicarbonate. ME:GE was unaffected by electrolyte inclusion. 5. Viscosity of ileal digesta supernatant fell (P < 0.01) with increasing bicarbonate inclusion but the value for the highest electrolyte level was still higher than for the control diet. 6. It is concluded that addition of both arginine and electrolyte is needed with a wheat/casein diet to improve performance to levels seen with a more commercial diet but that the determination of diet AME, with the type of fat addition used in this study, is unaffected by electrolyte balance. The interaction between electrolyte balance and in vivo viscosity requires further study.     

Effects of dietary fat type, pentosan level and xylanase supplementation on digestibility of nutrients and metabolizability of energy in male broilers.

A complete two by two by four factorial design was used to examine the main effects of dietary fat type (10% soya oil or 10% beef tallow), xylanase supplementation (with or without Avizyme 1300 at 1 g/kg diet) and pentosan level (7.7 g/kg, 11.0 g/kg, 14.3 g/kg and 17.6 g/kg soluble pentosans, respectively, by varying wheat/rye proportions) as well as their interactions on intestinal chyme conditions, nutrient digestibility and nutrient utilization in male broilers. Nutrient digestibilities for the total digestive tract and at various sites of small intestine were measured during the period from day 18 to 20 of age and at day 21 of age, respectively, using a marker technique. Jejunal and ileal supernatant viscosity increased in an exponential manner as dietary pentosan concentration was increased. This increase was more pronounced in tallow fed birds but was also found in enzyme treated groups albeit at a much lower level. Xylanase activity was still detectable in the ileum of birds fed enzyme supplemented diets but its activity was found to decrease as dietary pentosan content increased. Digestibility of crude protein and that of some amino acids at the terminal ileum was decreased as dietary pentosan content was increased and significantly improved by xylanase addition. No fat effect and no interactions were detected at this site. In contrast, measurements made over the whole gastrointestinal tract showed significantly lower protein and amino acid digestibility values for tallow fed birds, and significant higher enzyme effects especially in diets with higher pentosan concentrations. Nitrogen-corrected apparent metabolizable energy (AMEN) content and net protein utilization decreased with increasing dietary pentosan content and were significantly improved by xylanase addition and were lower in tallow fed birds. Again, xylanase effects were found to be more pronounced for tallow fed birds and at higher pentosan concentrations.     

The effects of adding xylanase, vitamin C and copper sulphate to wheat-based diets on broiler performance

1. The study used a 3 x 3 factorial design to evaluate the effects of 3 additives (none; vitamin C [250 mg/kg]; copper sulphate [250 mg/kg]) and 3 enzyme additions (none; Avizyme 1300 [Finnfeeds Ltd, 1 g/kg in food]; Avizyme 1310 [liquid spray, post-pelleting, 0.5 g/kg]). All experimental diets were mixed, heat-conditioned (80 degrees C for 2 min) and pelleted. Copper sulphate (diets NCu; DCu; LCu) and Avizyme 1300 (diets DN; DC; DCu) were added during mixing. Vitamin C was sprayed at 10 ml per kg (diets NC; DC; LC) and the liquid enzyme was diluted 20-fold and sprayed at the same rate (diets LN; LC; LCu), post-pelleting. 2. Additive or enzyme addition did not significantly affect DM intake or liveweight gain (LWG). Enzyme addition improved gain:food (P=0.014), AME:GE (P<0.001), ileal apparent digestibility of DM (P=0.008) and starch (P<0.001), faecal apparent digestibility of starch, crude fat and NDF (P=0.008; <0.001; <0.001 respectively) and reduced in vivo viscosity (P<0.001). 3. Copper sulphate addition depressed gain:food (P=0.047), AME:GE (P=0.002), ileal apparent digestibility of starch (P<0.001) and faecal apparent digestibility of starch (P=0.003) and crude fat (P<0.001) due to a negative additive x enzyme interaction when copper sulphate and dry enzyme were included together. 4. Vitamin C decreased in vivo viscosity by 20% but failed to have any effect on performance. Both enzyme forms gave similar improvements in performance in the absence of copper sulphate.     

Effect of diet form and enzyme supplementation on growth, efficiency and energy utilisation of wheat-based diets for broilers

1. The effect of diet form (mash, cold-pelleted, steam-conditioned/pelleted, wet mash, whole wheat with balancer pellet, restricted pellet) and enzyme inclusion (Avizyme 1300, absent, present) was studied in 2 trials using individually caged, male broilers from 14 to 42 d. Bird performance, viscosity of ileal contents and diet metabolisability (AME) were measured. 2. The performance of mash-fed birds was significantly poorer than for the other treatments in relation to dry matter intake, liveweight gain and gain:food. This was not due to reduced diet AME content. 3. There was no significant effect of heat treatment on any of the variables measured, although viscosity of ileal contents was increased by 30% as compared to the cold-pelleted diet. 4. Gain:food was improved with wet-mash feeding in comparison to the dry mash treatment but it was concluded that this was not due to any intrinsic improvement in diet quality, but rather to voluntary food restriction on introduction of the wet food. 5. Whole wheat feeding improved gain:food and diet AME content by 3% as compared to the complete diets and caused approximately a 50% increase in gizzard weight as compared with the pelleted diets. 6. Food enzyme inclusion did not improve performance although a significant improvement in diet AME content was observed with enzyme inclusion in trial 1.     

Interactions between dietary fat type and xylanase supplementation when rye‐based diets are fed to broiler chickens 2. Performance,nutrient digestibility and the fat‐soluble vitamin status of livers

1. The interactions between dietary fat type and xylanase supplementation of rye‐based diets were investigated using a 2×2 factorial design in which a rye‐based diet (610 g rye/kg) was combined with 100 g/kg of soya oil or beef tallow, with or without xylanase supplementation at 3000 IU/kg, and fed to 1‐d‐old male broilers for 35 d. Growth, nutrient digestibility and AMEn values were determined and the vitamin status of livers assessed at various ages.

2. There were significant interactions between crude fat and xylanase supplementation on the faecal digestibility of crude fat and crude protein. Fat digestibility was improved by xylanase in both fat type groups but to a greater extent for the tallow diets. However, the effects were found to be significant only for oleic, linoleic and linolenic acids. Similarly, protein digestibility and AMEn values were significantly improved by xylanase, but only for the tallow diet.

3. Heal digestibility of nitrogen and amino acids also were affected by enzyme for both fat type diets, the effect generally being more pronounced for the tallow diet.

4. The deposition of the fat soluble vitamins A and E in livers was significantly increased by xylanase supplementation and was also better for soya oil than for tallow.

5. Xylanase supplementation increased the digestibility of insoluble pentosans whereas for the soluble pentosans the opposite effect was noted.

6. Without xylanase supplementation the tallow‐based diet caused high mortality. Liveweight gain and the efficiency of food utilisation were greatest in the soya oil‐based, xylanase‐supplemented diet, followed by the unsupplemented soya oil‐, supplemented tallow‐ and unsupplemented tallow‐based diets.     

Lack of relationship between either specific weight or presence of the 1B1R gene and nutritive value of wheat in broiler diets

1. A study of the relationship between specific weight (SW) and nutritive value of wheat in diets offered to broilers up to 4 weeks of age was carried out using 10 varieties of wheat grown at three different locations; this gave rise to a range of specific weights from 59 to 76 kg/hl. 2. Because five varieties contained the 1B1R translocation and 5 did not, this allowed the effects of 1B1R on the performance of birds given high concentrations of dietary wheat to be further investigated. 3. The diets, which contained wheat at 744 g/kg with casein (142 g/kg) as the sole protein supplement, were heat-treated and pelleted. They were fed ad libitum to male, Ross broiler chicks from 7 to 28 d, in individual cages in a controlled environment room. 4. A 7 d excreta collection was made from 14 to 21 d for determination of apparent metabolisable energy (AME) content and wheat AME was calculated from the diet values. A separate determination of true metabolisable energy (TME) was undertaken using the method of McNab and Blair (British Poultry Science, 29: 697-707, 1988). 5. Wheat samples were analysed for proximate constituents, starch, total and soluble non-starch polysaccharides (NSP), amino acid content and gross energy and specific weight, thousand grain weight and in vitro viscosity were recorded. They were also subjected to near infrared reflectance spectroscopy (NIRS) with a view to establishing relationships with chemical constituents and performance parameters. 6. At 28 d the birds were humanely killed and in vivo viscosity was determined on the jejunal digesta supernatant. 7. There was quite a narrow range of crude protein content (N x 5.83) across the 30 wheat samples, the means for the three locations (Crossnacreevy, Downpatrick and Limavady, respectively) being 112, 121 and 122 g/kg. Starch contents of individual samples ranged from 604 to 679 g/kg, total NSP from 92.1 to 122.6 g/kg, soluble NSP from 17.6 to 32.6 g/kg and in vitro viscosity from 10.6 to 26.3 cps. 8. There were no significant varietal effects for dry matter intake (DMI), live weight gain (LWG) or gain:feed ratio. Apparent metabolisability of energy (ME:GE) for the diets ranged from 0.738 (Hussar) to 0.778 (Harrier) the effect being significant (P < 0.05) and there was a significant (P < 0.001) relationship (r(2) = 0.46) between ME:GE and gain:feed ratios. Calculated wheat AME for individual varieties ranged from 14.1 to 15.0 MJ/kg DM (P > 0.05). TME values ranged from 16.3 to 16.6 MJ/kg DM (NS). 9. In vivo viscosity ranged from 12.3 (Ritmo) to 23.7 cps (Hussar), the varietal effects being significant (P < 0.001). Viscosity was significantly higher for the 1B1R varieties than for the non-1B1R (22.7 vs 16.3 cps) but there were no significant effects on mean DM intake, LWG, gain:feed, ME:GE, calculated wheat AME, ME:gain (MJ AME per kg gain) or TME. 10. Wheat AME was negatively correlated (P < 0.05) with total NSP (slope -0.035) but was significantly affected by variety, constants ranging from 16.74 to 17.79. For wheat TME there were significant variety*total NSP interactions with slopes ranging from 0.29 to -0.07. There was no significant relationship between wheat AME and soluble NSP and there were significant variety*soluble NSP interactions for TME with slopes ranging from 0.09 to -0.14. 11. Despite the relatively wide range of in vitro viscosity there was no significant correlation of either calculated wheat AME or wheat TME with in vitro viscosity. For TME there were significant variety*viscosity interactions with slopes ranging from 0.21 to -0.13 (P < 0.001). There was also no significant correlation between soluble NSP and in vivo viscosity. 12. AME values for the NIRS calibration set varied from 13.7 to 15.6 MJ/kg and averaged 14.6 MJ/kg, whereas for the validation set, the values ranged from 14.0 to 16.1 MJ/kg with the mean value being 14.7 MJ/kg. The best correlation coefficient (r(2)) of 0.90 was obtained when the calibration sample set was subjected to SMLR using the second-order derivatised data. However, moving to validation, the outcome was extremely poor with 1-VR values being 0.12 and 0.09, respectively, for the external validation and an internal validation subset. 13. In summary, none of the production characteristics showed a good correlation with specific weight. Using the linear estimates for wheat AME and TME the effect of a 10 kg/hl change in SW equates to a 3 or 1.4% change, respectively. The estimate for AME is likely to be a worst-case value due to the high inclusion level of wheat. The range of calculated wheat AME (approximately 1 MJ) across the 30 wheat samples is similar to that seen in previous studies for wheat grown in Northern Ireland and much lower than in some other studies. 14. None of the other parameters examined gave any better relationship with nutritive value (assessed as AME or TME) than SW. This is a disappointing outcome, particularly in view of some previous studies which suggested that in vitro viscosity provides a good prediction of nutritive value.     

Interactions between dietary fat type and xylanase supplementation when rye‐based diets are fed to broiler chickens. 1. physicochemical chyme features

1. The interactions between fat type and xylanase supplementation of rye‐based diets were investigated using a 2 × 2 factorial design in which a rye‐based diet (610 g rye/kg) was combined with 100 g/kg of soya oil or beef tallow, with and without xylanase supplementation at 3000 IU/kg, and fed to 1‐d‐old male broilers. Food passage time, viscosity of digesta supernatant, xylanase activity and pH in different segments of the digestive tract were examined.

2. Food passage throughout the digestive tract was accelerated by enzyme addition regardless of fat type. The time taken for 50% of the marker to be excreted was reduced from 8.4 to 6.7 h in animals receiving the rye‐soya oil diets and from 8.0 to 6.9 h with the rye‐tallow diets.

3. Viscosity in the supernatant of the jejunal and ileal digesta was markedly decreased after enzyme addition. Viscosities were generally higher in the ileal than in the jejunal supernatant, and fell as the birds aged from 14 to 28 d. The effect of enzyme was also reduced in older chicks. There was not a clear effect of the fat source on viscosity.

4. Xylanase activity was still found at the end of the ileum in digesta of birds fed on the enzyme‐supplemented diets but not in control animals. Xylanase activity was also detected in the caeca of all groups.

5. Significantly lower pH values were found in tallow‐fed birds in some segments of the digestive tract. A significant increase in pH after enzyme addition was detected in the proximal ileum; this was independent of fat source.     

The effect of date fibre supplemented with an exogenous enzyme on the performance and meat quality of broiler chickens

1. Two experiments were conducted to evaluate the use of date fibre as a partial replacement of maize as a source of energy for growing broiler chicken. In experiment 1, date fibre was given alone to determine apparent metabolisable energy (AME) and apparent ileal digestibility of amino acids and crude fibre. 2. Date fibre had lower AME content (8.7 vs 13.6 MJ/kg) and apparent ileal digestibility coefficients for dry matter (0.35 vs 0.83), crude fibre (0.20 vs 0.54) and amino acids. 3. Based on the results of experiment 1, a growth study was conducted to test the effect of exogenous enzymes on the nutritive value of date fibre (experiment 2). 4. Three date fibre contents (5, 10 and 15%) with and without enzyme supplementation were evaluated. Daily feed intake, body weight gain and feed conversion ratio were measured. At the end of experiment 2, 160 birds were randomly selected and slaughtered to evaluate carcase and meat quality traits as well as measuring ileal viscosity. 5. Substitution of maize by 10 and 15% date fibre significantly depressed AME. Enzyme supplementation did not improve crude fibre digestibility. The inclusion of date fibre in the diets except at 5% decreased average daily gains, feed intake and feed conversion ratio. 6. Addition of date fibre caused a significant increase in the weights of total digestive tract, pancreas and caecum. Addition of date fibre or the exogenous enzyme had no significant effect on carcase or meat quality characteristics. 7. Date fibre increased ileal digesta viscosity compared to the control. Addition of the exogenous enzyme decreased the viscosity of the basal diets but had no effect on the date fibre diets.8. This study indicated that date fibre can be included at levels of 5% in broiler diets without affecting performance.     

Effects on chick performance and nutrient digestibility of an endo‐xylanase added to a wheat‐ and rye‐based diet in relation to fat source

1. A study with growing chicks investigated the effects of an inclusion of an endo‐xylanase preparation (LYXASAN®) to a wheat‐ and rye‐based diet on performance and nutrient digestibility in relation to the fat source.

2. The basal diet contained 500 g wheat and 100 g rye/kg of diet. The basal diet was supplemented with either 65 g soya oil/kg or 60 g blended animal fat and 5 g soya oil/kg.

3. Endo‐xylanase added to the soya oil diet did not affect weight gain, but there was a numerical improvement in food conversion efficiency which was not statistically significant. When the endo‐xylanase preparation was added to the blended animal fat diet, both weight gain and food utilisation were improved by 9.5% and 6.0%, respectively (P< 0.05).

4. Digestibilities of organic matter, crude fat, crude fibre and NFE were not significantly affected by adding endo‐xylanase to the soya oil diet. However, when endo‐xylanase was included in the blended animal fat diet, digestibility of organic matter, crude fat, crude fibre and NFE were improved (P<0–05). The improvement in fat digestibility was the most pronounced, amounting to 9–4%. Nitrogen retention and metabolisable energy content were improved significantly by the addition of an endo‐xylanase to the animal fat diet (P< 0.05), by 6.6% and 6.5% respectively.

5. From the results of this study, it can be concluded that the effects on chick performance and nutrient digestibility of a dietary endo‐xylanase in a wheat‐ and rye‐based diet are influenced to a considerable degree by the type of fat in the diet.     

Soft wheat instead of hard wheat in pelleted diets results in high starch digestibility in broiler chickens

(1) The aim of the experiment was to re-examine variations in digestibilities of food components in 3-week-old broiler chickens fed on pelleted diets based on wheats differing in lipase activity and hardness. Fourteen wheat (Triticum aestivum) samples, each from a different cultivar, were included at 550 g/kg in 14 different diets given to male Ross broiler chicks from 7 d of age. The other main ingredients consisted of soyabean meal (353 g/kg) and rapeseed oil (55 g/kg). A 15th diet containing durum wheat (Triticum durum) was also tested. (2) Hardness of wheats (Triticum aestivum) varied between 14 (very soft) and 88 (very hard), and lipase activity of wheats varied from 1 to 13.1 (relative scale). No significant correlation was found between in vitro viscosities and other parameters such as hardness, particle size of wheat flours and lipase. Hardness was correlated with the mean particle size of wheat flours and durability of pellets. (3) Individual lipid digestibilities were negatively correlated with in vitro viscosities of wheats. (4) Individual starch digestibilities were negatively correlated with wheat hardness, particle size of wheat flour before pelleting, and pellet durability. The ratio of measured AME(N) to predicted AME(N) was also negatively correlated with wheat hardness. Simple regression calculation showed that a 100-point increase in wheat hardness resulted in a 3% decrease in the AME(N) value of diets. Multiple regression calculation showed the food/gain ratio (d 10 to d 21) to be positively related to wheat hardness and negatively related to pellet durability. (5) Wheat lipase activity was positively correlated with individual starch digestibility, which was the reverse of a result obtained in a previous experiment. Thus, wheat lipase activity did not seem consistent for predicting starch digestibility and AME(N) values. (6) Among all wheat samples, durum wheat showed the highest protein content and the lowest content of water-insoluble cell-wall. Starch digestibility of durum wheat tended to be lower than that of other wheats (0.916 vs 0.936). However, no significant difference in AME(N) was observed between the durum wheat sample and other wheats. (7) Gut morphometric data measured at d 24 did not show significant differences between dietary treatments.     

Effects of wheat variety and specific weight on dietary apparent metabolisable energy concentration and performance of broiler chicks

1. This study used 4 wheat cultivars (Brigadier, Chaucer, Consort, Reaper) from three locations (Crossnacreevy, C; Downpatrick, D; Limavady, L), which had given rise to differences in wheat specific weight (SW), to examine the relationships between apparent metabolisable energy (AME) concentration, broiler performance and wheat SW. 2. The diets contained (g/kg): wheat 744, casein 142, blended vegetable fat 50, dicalcium phosphate 22, potassium bicarbonate 10.8, sodium bicarbonate 7.5, arginine 5, methionine 2, binder 8, trace minerals/vitamins 7.2, titanium dioxide 1.5. The diets were heat-treated (80 degrees C for 2 min) prior to pelleting (3 mm die). 3. SW ranged from 63 to 77 kg/hectolitre (hl), averaging 66, 69 and 76 kg/hl at D, C and L, respectively. In vitro viscosity of the wheat samples ranged from 5.2 to 17.5 cps and thousand grain weight (TGW) from 33.4 to 47.3 g. Mean TGW was similar at C and D (38.7, 37.0 g) but higher at L (43.1 g). In vitro viscosity was similar at C and L (11.2, 10.2 cps) but somewhat higher at D (14.4 cps). Crude protein (6.25 N) ranged from 116 to 147 g/kg and tended to be higher at D. Starch, which ranged from 612 to 656 g/kg, was least at D (617 g/kg) and greatest at L (641 g/kg). 4. Crude protein, crude fibre and total non-starch polysaccharide (NSP) were negatively correlated with SW, the R2 being respectively 0.38 (P<0.05), 0.16 (NS) and 0.45 (P<0.05). TGW and starch concentration were positively correlated with SW (R2=0.70, 0.44, respectively). There was a weak (NS) negative relationship (R2=0.19) between in vitro viscosity and SW. For both TGW and in vitro viscosity, correlations improved when variety was taken into account (R2=0.95, 0.92, respectively). 5. There were no significant effects of variety on dry matter (DM) intake or live weight gain (LWG). Gain: food was significantly higher (P<0.05) for Consort than for the other three varieties and the metabolisable energy ratio (ME:GE) just failed to attain significance (P=0.062). Calculated wheat AME (MJ/kg DM) was significantly (P<0.05) higher for Consort than for the other three wheats. There was a good correlation (R2=0.49) for the total data set between gain:food and ME:GE. In vivo viscosity varied from 13.6 to 28.6 cps for individual treatments and was significantly affected by variety (P<0001). 6. Although there were no significant differences in DM intake or LWG due to site the values for L (SW 76) were 6 and 5% lower, respectively, than for D (SW 66). Gain:food was lower (P<0.05) for C (SW 69) than for D. ME:GE, wheat AME and ME:gain were not significantly different between sites. 7. There was a weak (R2=0.18) positive relationship between ME:GE and SW corresponding to a 2.5% increase in energy value for a 10 kg/hl increase in SW and no relationship between gain:food and SW. When variety was taken into the regression the slope was similar but R2 increased to 0.82. 8. ME:GE and wheat AME concentration were negatively correlated with wheat in vitro viscosity (R2=0.64, 0.55, respectively). 9. It was concluded that in vitro viscosity appears to provide a better basis than SW for prediction of the nutritive value of wheats of unknown variety. If the variety is known then SW could be used to predict energy value. However, the effect of quite a large change in SW (10 kg/hl) was relatively small.     

Effects of xylanase supplementation on the apparent digestibility and digestible content of energy, amino acids, phosphorus, and calcium in wheat and wheat by-products from dry milling fed to grower pigs

Wheat by-products are feedstuffs that vary in nutritional value, partly because of arabinoxylans that limit nutrient digestibility. Millrun is a byproduct from dry milling wheat into flour and contains varying amounts of the bran, middlings, screening, and shorts fractions. The digestible nutrient content of mill-run is not well known. Effects of xylanase supplementation (0 or 4,000 units/kg of diet) on energy, AA, P, and Ca digestibilities were studied in a wheat control diet and 5 diets containing 30% of a by-product (mill-run, middlings, shorts, screening, or bran) in a 2 x 6 factorial arrangement of treatments. The wheat control diet was formulated to contain 3.34 Mcal of DE/kg and 3.0 g of standardized ileal digestible Lys/Mcal of DE. Diets contained 0.4% chromic oxide. Each of 12 ileal-cannulated pigs (32.5 +/- 2.5 kg) was fed 6 or 7 of 12 diets at 3 times the DE requirement for maintenance in successive 10-d periods for 6 or 7 observations per diet. Feces and ileal digesta were each collected for 2 d. Xylanase tended to increase (P < 0.10) ileal energy digestibility by 2.2 percentage units and the DE content by 0.10 Mcal/kg of DM and increased (P < 0.05) ileal DM digestibility by 2.8 percentage units; a diet x xylanase interaction was not observed. Xylanase increased (P < 0.05) total tract energy and DM digestibilities and the DE content. A diet x xylanase interaction was observed; xylanase increased (P < 0.05) total tract energy digestibility of the millrun diet from 72.1 to 78.9%, DE content from 3.19 to 3.51 Mcal/kg of DM, and DM digestibility from 71.5 to 78.6%. Diet affected (P < 0.05) and xylanase improved (P < 0.05) digestibility and digestible contents of some AA in diets and by-products, including Lys, Thr, and Val. Xylanase increased (P < 0.05) Lys digestibility by 13.8, 5.0, 5.2, 6.0, and 14.1 percentage units in millrun, middlings, shorts, screening, and bran, respectively. Diet affected (P < 0.01) total tract P and Ca digestibilities. Xylanase increased (P < 0.05) digestible P and Ca contents. In summary, nutrient digestibility varies among wheat by-products. Millrun contained 2.65 Mcal of DE/kg of DM, which xylanase increased to 3.56 Mcal of DE/kg of DM. Xylanase improved nutrient digestibility and DE content in wheat by-products; and the extent of improvement depended on the by-product. Xylanase supplementation may maximize opportunities to include wheat byproducts in swine diets and ameliorate reductions in nutrient digestibility that may be associated with arabinoxylans.     

Influence of whole wheat inclusion and a blend of essential oils on the performance, nutrient utilisation, digestive tract development and ileal microbiota profile of broiler chickens

1. The aim of the present experiment was to examine the influence of whole wheat inclusion and a blend of essential oils (EO; cinnamaldehyde and thymol) supplementation on the performance, nutrient utilisation, digestive tract development and ileal microbiota profile of broiler chickens. 2. The experimental design was a 2 × 2 factorial arrangement of treatments evaluating two wheat forms (ground wheat [GW] and whole wheat [WW]; 100 and 200 g/kg WW replacing GW during starter [1 to 21 d] and finisher [22 to 35 d] diets respectively) and two levels of EO inclusion (0 or 100 g/tonne diet). All dietary treatments were supplemented with 2000 xylanase units/kg feed. Broiler starter and finisher diets based on wheat and soybean meal were formulated and each diet fed ad libitum to 6 pens of 8 male broilers. 3. During the trial period (1-35 d), wheat form had no significant effect on weight gain or feed intake. However, WW inclusion tended (P = 0.06) to improve feed per gain. Essential oil supplementation significantly improved weight gain in both diets, but the improvements were greater in the GW diet as indicated by a significant wheat form × EO interaction. 4. Main effects of wheat form and EO on the relative weight, length and digesta content of various segments of the digestive tract were not significant. Significant interactions, however, were found for relative gizzard and caecal weights. Essential oil supplementation significantly increased the relative gizzard weight and lowered relative caecal weight in birds fed on the GW based diet, but had no effect in those fed on the WW based diet. 5. Whole wheat inclusion and EO supplementation significantly improved apparent ileal nitrogen digestibility. Apparent ileal digestible energy was not significantly influenced by the dietary treatments. 6. Ileal microbiota profiling, using denaturing gradient gel electrophoresis, showed that the ileal microbiota composition was influenced by feed form. The mean numbers of bacterial species in the ileal contents of birds fed on the GW diet supplemented with EO tended (P = 0.07) to be higher than those of the ileal contents of birds fed on unsupplemented GW based diet. 7. The present data suggested that dietary addition of EO improves broiler weight gain and ileal nitrogen digestibility both in GW and WW based diets, but that the magnitude of the response to EO for weight gain was greater in GW based diet. Whole wheat feeding was found to be beneficial in terms of feed efficiency.     

Sensitivity of broiler starters to three doses of an enzyme cocktail in maize-based diets

1. The aim of the present study was to investigate the effect of an enzyme cocktail composed of xylanase, amylase and protease on the performance and nutrient utilisation of broiler starters fed on a maize-based diet. A maize/soy-based control diet was formulated to be marginal in apparent metabolisable energy (AME) and amino acids and this diet was fed without or with two concentrations (250 and 500 g/tonne) of the exogenous enzyme cocktail. 2. Growth performance was measured over a 21-d period after which ileal contents were collected for measurement of digestible energy, nitrogen and dry matter. Excreta were collected from d 17 to 20 post-hatch and used to determine the AME, and retention of nitrogen and dry matter. 3. Supplementation of the control diet with 250 and 500 g/tonne of the enzyme cocktail resulted in enhanced performance of the chicks (1.4 and 8.3%, respectively, for weight gain and 1.2 and 2.2%, respectively, for feed per gain), but the improvements were significant (P < 0.05) only at 500 g/tonne. 4. Addition of both 250 and 500 g/tonne improved AME, nitrogen-corrected AME and dry matter retention compared with the control though the improvements were greater with the higher dose. These effects were also reflected in the apparent ileal digestibility coefficients of dry matter, nitrogen and energy, with 500 g/tonne of the enzyme cocktail improving ileal digestible energy by 3.4%. 5. These results demonstrate that a cocktail of exogenous enzymes containing xylanase, amylase and protease is effective in improving the performance of broiler chicks fed on a maize/soybean-meal-based diet. However, these benefits may be dose-dependent and so an economic analysis involving ingredient and enzyme pricing and the relative performance and digestibility enhancements could allow the end user to select the most economical dose to maximise return on investment.     

Effects of exogenous emulsifiers and fat sources on nutrient digestibility, serum lipids, and growth performance in weanling pigs.

Three experiments were conducted to determine whether emulsifiers improve utilization of fat from diets for early-weaned pigs. In Exp. 1, 96 weanling pigs (17 d old) were used in metabolism cages, with main effects of fat source (soybean oil, tallow, lard, and coconut oil) and emulsifier treatment (no emulsifier, lecithin, and lysolecithin as 10% of the added fat). Soybean oil and coconut oil were more digestible than tallow and lard (P < .001). Tallow was more digestible when lecithin and lysolecithin were added (P < .007), and pigs fed lecithin had lower serum triglycerides and cholesterol than pigs fed lysolecithin (P < .03). In Exp. 2, 270 weanling pigs (21 d old) were used in a growth assay. Treatments were 1) control diet; 2) Diet 1 with soybean oil; 3) Diet 1 with tallow; 4, 5, and 6) Diet 3 with lecithin replacing 5, 10, and 30% of the tallow, respectively; and 7, 8, and 9) Diet 3 with lysolecithin replacing 5, 10, and 30% of the tallow, respectively. At d 14 of the experiment, digestibility of tallow was improved more by lecithin than lysolecithin (P < .008). For the total experiment (d 0 to 35), the control pigs had poorer gain:feed ratio than did the pigs fed the fat sources (P < .002). In Exp. 3, 420 weanling pigs (21 d old) were used. Treatments were 1) control diet with soybean oil; 2) Diet 1 with tallow; and 3, 4, and 5) Diet 2 with 10% of the added fat as soybean oil, lecithin, or monoglyceride, respectively. Adding soybean oil, lecithin, and monoglyceride to tallow increased digestibility of total fat (P < .07). From d 0 to 14, pigs fed soybean oil gained weight faster than pigs fed the other treatments (P < .06), and pigs fed tallow without emulsifiers had the lowest ADG. Considering all experiments, addition of emulsifiers increased digestibility of nutrients but had minimal effect on growth performance.     

A comparison of the effects of different yeast products and antibiotic on broiler performance

1. The objectives of this experiment were to compare the effects of different yeast products, with different nucleotide contents and inclusion rates, on broiler performance and to compare the effects to those observed with an antibiotic growth promoter. 2. Two experiments were carried out over two time replicates, one in individual wire cages and one in group pens. 3. Birds were given a diet based on a commercial formulation, which was split into 7 batches. One batch (C) contained no growth promoter and acted as a negative control, another (AV) contained the antibiotic growth promoter Avilomycin (5 g/tonne) and acted as the positive control. The other batches contained yeast extract 2012 at 100 g/tonne (Y21), yeast extract 2012 at 500 g/tonne (Y25), standard yeast 18 at 100 g/tonne (Y81), standard yeast 18 enriched in nucleotides at 100 g/tonne (Y8N1) and standard yeast 18 enriched in nucleotides at 500 g/tonne (Y8N5). 4. In the penned experiment, 280 Cobb broiler chicks (40 birds/treatment) were randomised to diet and pen position on day of hatch. Birds were fed ad libitum until slaughter at 28 d. Bird performance was monitored during the experimental period. 5. In the individual cage experiment, 63 Cobb broiler chicks (9 birds/treatment) were taken from the pens at 7 d of age and randomised to diet and cage position. Birds were fed ad libitum from d 7 to d 28. A 7-d excreta collection was carried out to determine apparent metabolisable energy (AME) content and nutrient digestibility between d 14 and d 21. Bird intake and weight were monitored weekly during the experimental period. At 28 d the birds were killed and viscosity of jejunal digesta supernatant was determined. 6. In the penned experiment, diet had no significant effect on dry matter intake (DMI), live weight gain (LWG) or gain:feed values during any individual week of the experiment or for the entire experimental period. In the caged experiment, DMI was numerically highest for birds fed Y25 diet over the entire experimental period, however, this only reached significance in the second week. LWG, gain:feed, viscosity of jejunal contents and gizzard weight were not significantly affected by dietary treatment. 7. Diet AV had a significantly higher AME content than diets Y25, Y81, Y8N1 or Y8N5. Also, oil and neutral detergent fibre (NDF) digestibility coefficients were significantly affected by diet treatment.     

Influence of method of whole wheat inclusion and xylanase supplementation on the performance, apparent metabolisable energy, digestive tract measurements and gut morphology of broilers

1. The aim of the present study was to examine the influence of whole wheat inclusion and xylanase supplementation on the performance, apparent metabolisable energy (AME), digesta viscosity, and digestive tract measurements of broilers fed on wheat-based diets. The influence of the method of whole wheat inclusion (pre- or post-pelleting) was also compared. A 3 x 2 factorial arrangement of treatments was used with three diet forms (648 g/kg ground wheat [GW], GW replaced by 200 g/kg of whole wheat before [WW1] or after cold-pelleting [WW2]) and two xylanase levels (0 and 1000 XU/kg diet). 2. Birds given diets containing whole wheat had improved weight gains, feed efficiency and AME compared to those fed on diets containing ground wheat. The relative gizzard weight of birds fed WW2 diets was higher than in those fed GW and WW1 diets. Pre-pelleting inclusion of whole wheat had no effect on relative gizzard weight. Post-pelleting inclusion of whole wheat resulted in greater improvements in feed efficiency and AME than the pre-pelleting treatment. 3. Xylanase supplementation significantly improved weight gain, feed efficiency and AME, irrespective of the wheat form used. Viscosity of the digesta in the duodenum, jejunum and ileum were reduced by xylanase addition. Xylanase supplementation reduced the relative weight of the pancreas. 4. Neither xylanase supplementation nor whole wheat inclusion influenced the relative weight and length of the small intestine. 5. Xylanase supplementation increased ileal villus height. A significant interaction between diet form and xylanase was observed for ileal crypt depth. Xylanase supplementation had no effect on crypt depth in birds fed on diets containing GW, but increased the crypt depth in WW2 diets. No significant effects of diet form and xylanase supplementation were observed for the thickness of the tunica muscularis layer of gizzard or villus height, crypt depth, goblet cell numbers or epithelial thickness in the ileum. 6. Improved performance observed with post-pelleting inclusion of whole wheat was associated with increased size of the gizzard and improved AME. The gizzard development hypothesis, however, will not explain the improvements observed with pre-pelleting inclusion of whole wheat, suggesting the involvement of other factors.     

Effects of dietary fat type and xylanase supplementation in rye containing diets on energy metabolism in male broilers

Xylanase supplementation of rye-based diets which contained 10% beef tallow was shown to markedly improve the digestibility of fat whereas the enzyme effect in diets containing 10% soya oil was much less pronounced (Dänicke et al. 1997b). Such interactions between fat type and xylanase supplementation have also been reported for wheat–rye-based diets (Langhout et al. 1997) and wheat-based diets (Allen et al. 1997) and were attributed mainly to the fatty acid composition of different types of fat and to changes in digesta viscosity caused by soluble pentosan. The apparent metabolizable energy, N-corrected (AME_N) contents of such diets were affected in a similar manner suggesting that energy metabolism is also influenced by xylanase supplementation and the type of dietary fat. However, changes in the metabolizability of gross energy does not necessarily indicate whether the efficiency of metabolizable energy (ME) for energy gain is changed nor if different proportions of ME are used for maintaining an energy equilibrium, i.e. ME maintenance requirement. In addition, studies suggest that both dietary fat level and fat type might exert effects on the efficiency of utilization of ME for energy retention (Carew and Hill 1964; de Groote et al. 1971; Fuller and Rendon 1979; Brue and Latshaw 1985). Hence, the aim of this study was to investigate the partitioning of ME between maintenance needs and energy retained as protein and as fat when feeding rye-based diets. The diets contained either soya oil or beef tallow and were either unsupplemented or xylanase-supplemented.