Influence of partial replacement of ground wheat with whole wheat and exogenous enzyme supplementation on growth performance,nutrient digestibility and energy utilization in young broilers

This study investigated the influence of pre‐pelleting inclusion of whole wheat (WW) and exogenous enzyme supplementation on growth performance, coefficient of apparent ileal nutrient digestibility (CAID) and apparent metabolizable energy (AME) in broilers fed wheat‐based pelleted diets. A 2 × 3 factorial arrangement of treatments was used with two methods of wheat inclusion [622 g/kg ground wheat (GW) and 250 g/kg WW replaced GW (wt/wt) pre‐pelleting (PWW)] and three enzymes (xylanase, phytase and xylanase plus phytase). A total of 288, one‐day‐old male broilers (Ross 308) were individually weighed and allocated to 36 cages (8 broilers/cage), and the cages were randomly assigned to the six dietary treatments. Birds fed PWW diets gained more (p < 0.05) weight than those fed GW diets. There was no effect (p > 0.05) of WW inclusion on feed intake (FI). Phytase alone increased (p < 0.05) FI compared to xylanase or the combination. Whole wheat inclusion increased (p < 0.05) the gain‐to‐feed ratio (G:F). Feeding xylanase plus phytase and phytase‐added diets resulted in the greatest and lowest G:F, respectively, with xylanase supplemented diets being intermediate. Birds fed PWW diets had greater (p < 0.05) relative gizzard weights than those fed GW diets. There was no effect (p > 0.05) of WW inclusion on the CAID of nitrogen (N), starch and fat. Combination of xylanase and phytase resulted in greater (p < 0.05) digestibility of N, starch and fat than that of individual additions. Feeding PWW diets resulted in greater (p < 0.05) AME values than GW diets. Combination of xylanase and phytase increased (p < 0.05) the AME compared to the diets with individual additions of xylanase or phytase. The current results suggest that the influence of pre‐pelleting WW inclusion and exogenous enzymes on nutrient digestibility and broiler performance is not additive.     

Evaluation of Heat-Stable Phytases in Pelleted Diets Fed to Broilers from Day Zero to Thirty-Five During the Summer Months

Supplementing phytase to broiler diets has been shown to improve phytate P digestibility in commercial broilers. Broiler rations are typically pelleted to promote improved broiler performance, but high pelleting temperatures can inactivate phytase enzymes. Before the introduction of heat-stable phytase products, phytase enzymes were generally added postpelleting to limit the effect of pelleting temperature on phytase activity. Therefore, the objective of this study was to evaluate postpelleting phytase activity of 3 concentrations of 2 heat-stable phytase enzymes and their efficacy when fed to 0- to 35-d-old broilers. After pelleting the phytase-supplemented diets at 93.3°C, the retained phytase activities of the 2 enzymes were similar, suggesting equivalent heat stability. Supplementing phytase to deficient nonphytate P diets improved FCR by 3% (P ≤ 0.05) compared with the FCR of birds fed an unsupplemented deficient diet. No differences in tibia ash (TA) were detected between the 2 phytase sources; however, TA of birds fed supplemental phytase at the 2 greatest concentrations was improved (P ≤ 0.05) compared with the TA of birds fed nonphytate P-deficient diet. These results suggest that the prepelleting inclusion of heat-stable phytase enzymes may be a viable alternative to postpellet application of phytase for improving P utilization in broilers.     

Prediction of ingredient quality and the effect of a combination of xylanase, amylase, protease and phytase in the diets of broiler chicks. 2. Energy and nutrient utilisation

1. In order to investigate the effects of xylanase, amylase, protease and phytase in the diets of broiler chickens containing graded concentrations of metabolisable energy (ME), two 42-d experiments were conducted using a total of 2208 broiler chicks (8 treatments with 12 replicate pens in each experiment). 2. Four diets including one positive and three negative control diets were used. Three maize/soybean meal-based negative control (NC) diets were formulated to be identical in available phosphorus (P), calcium (Ca) and amino acids but NC1 contained approximately 0.17 MJ/kg less ME than NC2 and approximately 0.34 MJ/kg less ME than NC3. A positive control (PC) was fed for comparison and was formulated to be adequate in all nutrients, providing approximately 0.63 MJ/kg ME, 0.13% available P, 0.12% Ca and 1 to 2% amino acids more than NC1. 3. The reduction in nutrient density between NC1 and PC was determined using ingredient quality models Avichecktrade mark Corn and Phychecktrade mark that can predict the response to exogenous enzymes in maize/soybean meal-based broiler diets. Supplementation of each diet with or without a cocktail of xylanase, amylase, protease and phytase gave a total of 8 dietary treatments in a 4 x 2 factorial arrangement. The same treatments and diet designs were used in both experiments but conducted in different locations using different batches of maize, soybean meal and minor ingredients. 4. In both experiments, digestibility was improved by the addition of exogenous enzymes, particularly those for P, Ca and certain amino acids. In addition, the supplementation of the PC with enzymes elicited a positive response indicating that over-the-top addition of xylanase, amylase, protease and phytase may offer a nutritionally and economically viable alternative to feed cost reduction. 5. It can be concluded that the digestibility of nutrients by broilers fed on maize/soybean meal-based diets can be improved by the use of a combination of xylanase, amylase, protease and phytase.     

Optimum inclusion of field peas, faba beans, chick peas and sweet lupins in poultry diets. II. Broiler experiments

1.Three experiments were undertaken to determine the optimum inclusion rates of field peas, faba beans, chick peas and sweet lupins in broiler starter and finisher diets in amounts up to 360 g/kg. 2. In experiment A chickens in cages grown to 21 d on diets with field peas and faba beans gave better growth rate and feed efficiency than those with sweet lupins and chick peas. Growth rate and Food conversion ratio (FCR) improved with increasing amounts of faba beans in the diet while for chick peas growth rate and FCR declined. Digesta viscosity and excreta stickiness scores were much higher on diets with sweet lupins. Steam pelleting improved growth rate and FCR on all diets. 3. In experiment B birds were in cages and grown from 21 to 42 d. There were no differences between grain legumes (when combined for all inclusions) for growth rate, food intake or FCR. Viscosity was again much higher on the sweet lupin-based diets while the pancreas was significantly enlarged on the diets with chick peas, as observed previously in chickens grown to 21 d. Steam pelleting of diets gave a consistent and positive response for weight gain and FCR. 4. Experiment C was carried out in pens each holding 60 birds under semi-commercial conditions and grown to 42 d on starter and finisher diets with the same grain legumes as used previously but each at 2 rates of inclusion similar to those in commercial practice. Field peas at 200 to 300 g/kg and chick peas at 150 to 220 g/kg gave inferior growth to faba beans (150 to 180 g/kg) and sweet lupins (120 g/kg). 5. The results of these experiments allowed tentative recommendations to be made to industry for inclusion rates of these cultivars of the 4 grain legumes. These were: field peas 300 g/kg; faba beans 200 g/kg, chick peas 100 g/kg and sweet lupins <100 g/kg. Wet droppings and high gut viscosity were serious problems with sweet lupins although these were not so obvious in experiment C.     

Evaluation of keratinase stability in pelleted broiler diets

Versazyme (VZ) is an approved keratinase-based feed additive produced naturally as a fermentation product of Bacillus licheniformis PWD-1. The experiment was designed to test the recovery and efficacy of VZ using typical feed industry pelleting parameters. The pelleted diets were conditioned to 85°C for 30 s and pelleted using a 4 × 32 mm die, cooled, and crumbled. A total of 192 male broiler chicks were fed a corn-soybean meal starter diet formulated at 18.5% CP to 21 d of age. The 4 treatments used in the feeding study were as follows: VZ 0.0%-mash, VZ 0.0%-pellet, VZ 0.1%-mash, and VZ 0.1%-pellet. Body weight and feed consumption were determined at 21 d of age. The recovery of VZ in feed was 93% in the mash diet and 66% in the pelleted diet. There was a 55-g increase in BW gain and 0.17 improvement of FCR when birds were supplemented with 0.1% VZ. Pelleting improved BW gain (P < 0.05) but did not significantly improve the FCR. Growth performance results indicate that pelleting did not affect the efficacy of VZ.     

Short- and Long-Term Effects of Feed Form on Fast- and Slow-Growing Broilers

Three experiments were conduced to quantify the potential negative effect of fine particles (<0.5 mm diameter) in the feed on fast- and slow-growing broiler growth performance. In the first experiment, chickens were fed mash or pellets of 2.5 and 4 mm diameter between 15 and 35 d of age. During this period, fast-growing broiler fed pelleted feed had a 19% higher final BW, a 12% higher feed intake, and a 12% lower (improved) feed conversion ratio than those fed mash. Feed form had no significant effect on feed intake, BW gain, or final BW of slow-growing chickens. Feed conversion ratio, however, was 6% lower with pellet than mash. In the second and the third experiments, fast and slow-growing chickens weighed 1.2 kg at the beginning of the experiment. In the second experiment, the effects of a transition from pelleted feed to mash or a mixture between the 2 feed forms on the short-term feed intake and growth was investigated. After the transition from pellet to mash or the mixture, both fast- and slow-growing chickens adapted their feed intake in less than 10 min. The mixture between mash and pellets led to a 25% higher feed intake and an 18% lower feed conversion ratio for fast-growing chickens. There was no significant difference between mash and the mixture on slow-growing feed intake, but feed conversion ratio was 9% lower. In the third experiment, the effect of fine particles concentration in the feed on short-term growth response was measured. Increase in the concentration of fine particles in the feed linearly reduced feed intake and BW gain of both fast- and slow-growing chickens. However, the slope was 5 times greater for fast-growing chickens than for slow-growing chickens. These 3 experiments showed that fast-growing chickens are more sensitive to feed form than slow-growing chickens. Therefore, physical form of the feed can be a major limiting factor of performance.     

Prediction of ingredient quality and the effect of a combination of xylanase, amylase, protease and phytase in the diets of broiler chicks. 1. Growth performance and digestible nutrient intake

1. A total of 2208 broiler chicks were used in two growth experiments (8 treatments and 12 replicate pens in each experiment) to assess the effects of xylanase, amylase, protease and phytase in maize-based diets. 2. A positive control diet was formulated containing adequate nutrient concentrations. A negative control diet was formulated to contain approximately 628 kJ/kg, 0.13%, 0.12% and 1 to 2% less metabolisable energy (ME), phosphorus (P), calcium (Ca) and amino acids, respectively, than the positive control. In addition, two further negative control diets that contained 167 or 334 kJ/kg more ME, respectively, than negative control 1 were formulated. 3. A further 4 dietary treatments were made by supplementing each of the 4 negative control diets with a combination of xylanase, amylase, protease and phytase, resulting in 8 dietary treatments in a 4 by 2 factorial arrangement. 4. The scale of the removal of energy, P, Ca and amino acids from the positive control diet was determined using least square models based on in vivo data for both the xylanase/amylase/protease cocktail and for phytase and it was predicted that performance of birds fed on negative control 1 would be returned by supplemental enzymes to that of those fed on the positive control. 5. In both experiments there was a significantly poorer performance in birds fed on the negative control 1 than in those fed on the positive control. The poorer weight gain and feed conversion ratio could be attributed in part to a reduced intake of digestible energy, P, nitrogen (N) and amino acids associated with birds fed on the negative control diet. 6. Supplementation of the negative control diets with the enzyme combination returned performance to that of the positive control in both experiments. 7. These data indicate that exogenous xylanase, amylase, protease and phytase can be used successfully in a strategically formulated low nutrient density diet to maintain performance to that of birds fed on a nutritionally adequate diet.     

Main effects and interactions of varying formulation protein,fiber, and moisture on feed manufacture and pellet quality

The majority of broiler feed is in pelleted form. Feeding pelleted diets results in improved BW gain and FE compared with feeding mash diets. However, improvements in performance are contingent on pellet quality. Past research has focused on methods to improve pellet quality without negatively affecting processing variables and performance. The objective of these studies was to evaluate the effects and interactions that occur when small inclusion amounts of fiber, protein, and moisture were formulated into corn- and soybean-based broiler diets. Two experiments were conducted. In experiment 1, small inclusion amounts (5%) of fiber (in the form of cellulose) or protein (in the form of soy protein isolate) improved the pellet durability index and the modified pellet durability index compared with the control (P ≤ 0.05). Moreover, manufacturing variables were not negatively affected (P > 0.05). In experiment 2, small inclusion amounts of protein (2%), in the form of soybean meal, and moisture (2 and 4%), in the form of tap water, improved the pellet durability index and the modified pellet durability index (P ≤ 0.05). Small inclusion amounts of fiber, in the form of oat hulls, negatively affected pellet quality and manufacturing variables. Ingredient interactions were not observed for manufacturing variables or pellet quality. These results demonstrate that small inclusion amounts of supplemental fiber (cellulose), protein (soy protein isolate or soybean meal), and moisture (tap water) can be used to ameliorate poor pellet quality.     

The effect of conditioning temperature and exogenous xylanase addition on the viscosity of wheat-based diets and the performance of broiler chickens

1. A total of 1920 Ross broiler chicks were used in a 6 treatment by 8 replicate growth study to investigate the effect of conditioning temperature and exogenous xylanase addition on diet characteristics and bird performance. 2. Increasing conditioning temperature from 80 to 90 degrees C increased the viscosity of the diets by approximately 6 mPa.s and reduced body weight gain of the broiler chickens by 7%. 3. Furthermore, there was a significant interaction between temperature and the addition of exogenous xylanase, with a proportionately greater positive response to added xylanase in the diets that were pelleted at higher temperatures. 4. Addition of exogenous xylanase also increased the proportion of soluble arabinoxylan in the feed and reduced dietary viscosity, which is likely to be related to the degree of polymerisation of the soluble carbohydrate. 5. These results suggest that conditioning temperature should be considered as a factor when attempting to predict the response of broilers to added xylanase, especially when high-viscosity or 'low-quality' wheat is being used. 6. It can be concluded that pelleting wheat-based diets above 80 degrees C can compromise bird performance and that, if higher temperatures are to be employed, the use of exogenous xylanase is critical to maintain productivity.     

Effects of the Addition of Roller Mill Ground Corn to Pelleted Feed on Pelleting Parameters,Broiler Performance,and Intestinal Strength

Maintaining an optimal pelleting production rate can be difficult when manufacturing feeds for meat birds. Increased production time may be required to fill feed demand and feed outages occur if demand is not met. Identifying management strategies to enhance overall feed production rate without compromising broiler performance is warranted. This study examined the effects of adding varying amounts of corn, ground through a roller mill, to pelleted supplements on feed production parameters, growth performance, and intestinal strength of broiler chickens. Four treatments were used from 18 to 41 d, which included a control (total diet pelleted), and addition of rolled corn to pelleted supplements at 15, 25, and 35% of the corn required in diet formulation. The final diets fed were identical in nutrient composition. Decreasing the amount of ground corn in the pelleted supplement did not affect pellet durability index in the grower diet, but pellet quality declined in the finisher diet. The dietary treatments did not adversely affect final BW gain or feed conversion. Progressive additions of ground corn to pelleted supplement did not affect gizzard weight or peak force intestinal strength. These data indicate that 35% of the formula corn can be added postpellet to reduce electrical cost for grinding and pelleting and improve overall production rate without adversely affecting cumulative growth performance of broilers.     

Nutritional Evaluation of a High-Oil Sunflower Meal in Broiler Starter Diets

Two experiments were conducted with broiler chicks to determine the nutritive value of high-oil sunflower meal (HO-SFM), a sunflower oil extraction by-product obtained through screw-press extraction and expanding processes with a proximate composition of 32% CP, 12% crude fiber, and 19% ether extract. In Experiment 1, the effects of a high level (46.4%) of HO-SFM on chick performance and gastrointestinal organs were tested. The objective of Experiment 2 was to determine if pelleting the feed could overcome the bulkiness resulting from inclusion of HO-SFM at a high level. The results of Experiment 1 indicated that addition of 46.4% HO-SFM to broiler starter diets significantly (P < 0.05) depressed body weight, feed intake, and gain but not feed conversion. Fat pad and liver lipid were again significantly (P < 0.05) decreased in the HO-SFM treatment. Impaired performance might have been due to the difference of the density of HO-SFM diet (608 g/L) compared with the soybean meal control (723 g/L). When bulkiness was overcome by pelleting in Experiment 2, it was found that pelleting the feed significantly enhanced growth of broiler chicks compared with SFM or soybean meal mash diets. Liver weights and lipid content were again decreased in HO-SFM diets. The results of this study suggest that HO-SFM can be used up to 28% without adverse effects on broiler chicks. Further improvement was observed with pelleting. Liver weight and lipid content were consistently reduced by feeding HO-SFM.     

Effect of diet containing phytate and phytase on the activity and messenger ribonucleic acid expression of carbohydrase and transporter in chickens

The effect of dietary phytate and phytase on carbohydrase activity and hexose transport was investigated in broiler chickens. Diets containing phytate P (2.2 or 4.4 g/kg) with different phytase dose rates (0, 500, or 1,000 phytase units/kg) were fed to 504 female Cobb chicks for 3 wk. Diets containing high phytate concentrations depressed (P < 0.05) BW and G:F, whereas phytase supplementation improved (P < 0.05) the performance of birds. In the duodenum, phytate decreased (P < 0.05) the activities of disaccharidases, Na(+)K(+)-ATPase, and glucose concentrations by 5 to 11%, but phytase enhanced (P < 0.05) the concentrations of amylase, sucrase, maltase, Na(+)K(+)-ATPase, and glucose by 5 to 30%. In the jejunum, phytate decreased (P < 0.05) the concentrations of amylase, sucrase, Na(+)K(+)-ATPase, and glucose by 10 to 22%, and phytase alleviated the negative effect of phytate on the above variables. Ingestion of diets containing phytate also decreased (P < 0.05) serum amylase activity and glucose concentration, and phytase enhanced (P < 0.05) serum concentrations of amylase, sucrase, maltase, Na(+)K(+)-ATPase, and glucose. There were also interactions (P < 0.05) between phytate and phytase on the concentrations of serum amylase, duodenal amylase, sucrase, and jejunal glucose. Enzymatic analysis at a molecular level showed that neither phytate nor phytase influenced the mRNA expression of sucrase-isomaltase in the small intestine. Also, the investigation into the sodium glucose cotransporter gene may challenge the mechanism by which phytate interferes with glucose utilization, as partly indicated by bird performance, and transmembrane transport because diets containing increased phytate upregulated (P < 0.05) the mRNA expression of the sodium glucose cotransporter gene in duodenum and did not influence it in the jejunum. These results indicate that phytate can impair endogenous carbohydrase activity and digestive competence, and phytase can ameliorate these effects for chickens.     

Optimum inclusion of field peas, faba beans, chick peas and sweet lupins in poultry diets. I. Chemical composition and layer experiments

1.Experiments were undertaken to determine the chemical composition and apparent metabolisable energy (AME) of field peas, faba beans, sweet lupins and chick peas and the production of hens when each was included in nutritionally similar diets at 250 g/kg in 2 experiments. 2. Amino acid composition, crude protein and AME agreed well with previously published measurements. Detailed analysis of the non-starch polysaccharides (NSPs) showed that sweet lupins were much higher than the other grain legumes in the soluble NSPs and that the NSPs were particularly high in arabinose. The condensed tannin content was highest in field peas followed by faba beans. 3. In the 1st layer experiment over 40 weeks, hen-day egg production was lowest on the faba bean-based diet and egg weight and egg mass were also lowest. Relative viscosity of digesta in the small intestine of hens fed on the sweet lupin-based diet was highest, followed by that of hens fed on field peas. Enlargement of the pancreas was observed in hens consuming chick peas. 4. In experiment 2, in which only sweet lupins and faba beans were used, steam or cold pelleting showed few effects, nor did dehulling of faba beans but egg weight was lower when diets were steam pelleted. Daily food intake was 5.7 g/bird lower on the steam than cold pelleted diets and food conversion ratio tended to be improved (P=0.082). 5. It was concluded that field peas could support good production at 250 g/kg of layer diet. Although chick peas and sweet lupins supported good performance, there was concern about the increased weight of the pancreas and high gut viscosity respectively. Faba beans showed similar hen-d egg production in the 2nd experiment to that of sweet lupins but egg weight tended to be about 0.8 g lower than when on the sweet lupin-based diets.     

Nutrient digestibility and performance responses of growing pigs fed phytase- and xylanase-supplemented wheat-based diets

Three experiments were conducted to evaluate the effect of supplementing phytase and xylanase on nutrient digestibility and performance of growing pigs fed wheat-based diets. In Exp. 1, 10 diets were fed to 60 pigs from 20 to 60 kg of BW to determine the effect of combining phytase and xylanase on apparent total tract digestibility (ATTD) of nutrients and growth performance. The 10 diets included a positive control diet (PC; 0.23% available P; 0.60% Ca) and a negative control diet (NC; 0.16% available P; 0.50% Ca) supplemented with phytase at 0, 250, and 500 fytase units (FTU)/kg and xylanase at 0, 2,000, and 4,000 xylanase units (XU)/kg in a 3 x 3 factorial arrangement. In Exp. 2, 6 ileally cannulated barrows (initial BW = 35.1 kg) were fed 4 wheat-based diets in a 4 x 4 Latin square design, with 2 added columns to determine the effect of combining phytase and xylanase on apparent ileal digestibility (AID) of nutrients. The 4 diets were NC (same as that used in Exp. 1) or NC supplemented with phytase at 500 FTU/kg, xylanase at 4,000 XU/kg, or phytase at 500 FTU/kg plus xylanase at 4,000 XU/kg. In Exp. 3, 36 barrows (initial BW = 55.5 kg) were fed 4 diets based on prepelleted (at 80 degrees C) and crumpled wheat for 2 wk to determine the effect of phytase supplementation on ATTD of nutrients. The 4 diets fed were a PC (0.22% available P; 0.54% Ca) and a NC (0.13% available P; 0.43% Ca) alone or with phytase at 500 or 1,000 FTU/kg. All diets in the 3 experiments contained Cr(2)O(3) as an indigestible marker. No synergistic interactions were detected between phytase and xylanase on any of the response criteria measured in Exp. 1 or 2. There were no dietary effects on growth performance in Exp. 1. In Exp. 1, phytase at 250 FTU/kg increased the ATTD of P and Ca by 51 and 11% at 20 kg of BW or by 54 and 10% at 60 kg of BW, respectively, but increasing the level of phytase to 500 FTU/kg only increased (P < 0.05) ATTD of P at 20 kg of BW. In Exp. 2, phytase at 500 FTU/kg increased (P < 0.05) the AID of P and Ca by 21 and 12%, respectively. In Exp. 3, phytase at 500 FTU/kg improved (P < 0.05) ATTD of P by 36%, but had no further effect at 1,000 FTU/kg. Xylanase at 4,000 XU/kg improved (P < 0.05) AID of Lys, Leu, Phe, Thr, Gly, and Ser in Exp. 2. In conclusion, phytase and xylanase improved P and AA digestibilities, respectively, but no interaction between the 2 enzymes was noted.     

Growth response of broilers to spray-dried plasma in pelleted or expanded feed processed at high temperature

A series of 4 experiments evaluated effects of mash conditioning temperature from a pellet mill or expander on performance of broilers fed pelleted diets containing spray-dried plasma (SDP). All experiments utilized Ross x Ross 308 male broilers randomly assigned to their respective treatments (6 or 10 broilers/pen and 8 or 10 pens/treatment). Treatments in Exp. 1 consisted of a control (0% SDP), SDP coated postpelleting, or SDP blended into the meal prepelleting. Experiment 2 and 3 included the same 3 treatments as in Exp. 1 but with additional treatments of SDP blended into the meal and conditioned at 90 or 95 degrees C before pelleting. In Exp. 4, treatments consisted of a control (0% SDP) or SDP blended into the meal and pelleted (85 degrees C conditioning temperature) or expanded (149 degrees C final effective temperature) and then pelleted. Corn-soybean meal-based diets were formulated to be equal in lysine and ME in all experiments. Pelleted diets were conditioned for 15 s at 85 degrees C, and expanded diets were conditioned at 95 degrees C, 29.7 MJ/t, 13.95 kg/cm2 cone pressure, exit temperature of 149 degrees C, and then pelleted through a 4 x 32-mm die. In Exp. 1, ADG and feed intake were improved (P < 0.05) for broilers fed SDP from d 1 to 28 of age, with greater BW at d 42. In Exp. 2, both in early (d 1 to 28 of age) phases, and overall (d 1 to 42 of age), broilers fed SDP had improved (P < 0.05) gain and efficiency. In Exp. 3, ADG, feed intake, efficiency of gain, and BW were improved (P < 0.01) for broilers fed SDP from d 1 to 21 of age, regardless of conditioning temperature. In Exp. 4, broilers fed SDP had improved (P < 0.05) gain, BW, and feed intake regardless of processing method. Overall, the results of all of the experiments demonstrated that pellet conditioning temperature from 85 to 95 degrees C and expander temperatures to 149 degrees C did not impair the positive growth effects of SDP in pelleted or expanded broiler feed.     

Influence of phytase and xylanase, individually or in combination, on performance, apparent metabolisable energy, digestive tract measurements and gut morphology in broilers fed wheat-based diets containing adequate level of phosphorus

1. The aim of the present study was to examine the influence of microbial phytase and xylanase, individually or in combination, on performance, apparent metabolisable energy, digesta viscosity, digestive tract measurements and gut morphology in broilers fed on wheat-soy diets containing adequate phosphorus (P). The wheat-soy basal diet was formulated to contain 4.5 g/kg non-phytate P and the experimental diets were formulated by supplementing the basal diet with xylanase (1000 xylanase units/kg diet), phytase (500 phytase units/kg diet) or a combination of phytase and xylanase. 2. Supplemental phytase improved the weight gains and feed efficiency by 17.5 and 2.9%, respectively. Corresponding improvements due to the addition of xylanase were 16.5 and 4.9%, respectively. The combination of phytase and xylanase caused no further improvements in broiler performance. 3. Individual additions of xylanase or phytase resulted in numerical improvements in apparent metabolisable energy (AME), but the differences were not significant. The combination of the two enzymes significantly increased AME. Addition of xylanase and the combination of the two enzymes reduced the viscosity of digesta in all sections of the intestine. Phytase supplementation reduced digesta viscosity in the duodenum and ileum, but not in the jejunum. 4. Enzyme supplementation lowered the relative weight and length of the small intestine. Additions of xylanase and phytase reduced the relative weight of the small intestine by 15.5 and 11.4%, respectively, while the corresponding reductions in the relative length of the small intestine were 16.5 and 14.1%, respectively. The combination of phytase and xylanase had no further effects on the relative weight and length of the small intestine compared with the xylanase group. 5. The addition of phytase increased villus height in the duodenum and decreased the number of goblet cells in the jejunum compared with those on the unsupplemented basal diet. Xylanase supplementation tended to increase goblet cell numbers in the duodenum and decreased crypt depth in thejejunum. The combination of phytase and xylanase increased villus height in the ileum and crypt depth in thejejunum and ileum. 6. In summary, the present results showed that the addition of a microbial phytase, produced by solid state fermentation and containing significant activities of beta-glucanase and xylanase, was as effective as xylanase in improving the performance of broiler chickens fed on wheat-based diets containing adequate levels of P. Improved performance with enzyme supplementation was generally associated with reduced digesta viscosity, increased AME, and reduced relative weight and length of small intestine.     

Effect of Corn Particle Size and Pellet Texture on Broiler Performance in the Growing Phase

A review of past literature revealed inconsistencies in recommended grain particle size for optimal broiler performance. Changing diet formulation and subsequent processing variables may alter pellet texture and potentially affect broiler performance. In the current study, ground corn, varying in size (781, 950, 1,042, 1,109, and 2,242 μm), was added to a soybean-based premix to create 5 different mash diets. Water and a commercial pellet binder were added separately to corn-soybean-based diets before steam pelleting to create 2 pelleted diets differing in texture (soft and hard, respectively). The objective was to evaluate corn particle size, pellet texture, and feed form variation of compound diets on 3- to 6-wk broiler performance, nutrient retention, carcass characteristics, TME_n, feed passage time, and particle size preference. Soft and hard pellets had similar pellet durability (90.4 and 86.2%, respectively) and fines (44.5 and 40.3%, respectively). Increasing particle size of mash diets improved nutrient retention. However, broiler performance and energy metabolism were decreased when corn particle size exceeded 1,042 μm. This observation was due, in part, to increased size and maintenance requirement of the gastrointestinal tract. Broilers fed hard pellets (1,856 g of pellet breaking force) had improved nutrient retention, TME_n, and subsequent performance compared with broilers fed soft pellets (1,662 g of pellet breaking force). Pellet texture may affect broilers in a manner similar to particle size.     

Influence of phytate level on broiler performance and the efficacy of 2 microbial phytases from 0 to 21 days of age

Phytate is an antinutrient in animal feeds, reducing the availability and increasing the excretion of nutrients. Phytases are widely used to mitigate the negative influences of phytate. This trial was designed to compare the efficacy of 2 Escherichia coli-derived phytases on broiler performance and bone ash as influenced by dietary phytate level. A total of 1,024 Arbor Acres male broilers were used with 8 replicate pens of 16 birds/pen. Experimental diets were based on low available phosphorus (avP; 1.8 g/kg) with low (6.40 g/kg) or high (10.65 g/kg) phytate. The low-avP diets were then supplemented with mono-dicalcium phosphate to increase the avP level to 4.5 g/kg, 500 phytase units/kg of phytase A, or 500 phytase units/kg of phytase B to create 8 experimental diets. Feed intake, BW gain, FCR, and livability were influenced by a P source × phytase interaction. Feed intake, BW gain, and livability were reduced and FCR was higher in broilers fed low-avP diets, particularly in the presence of high phytate. Phytase A or phytase B improved feed intake, BW gain, and FCR, particularly in the high-phytate diet. However, broilers fed phytase A ate more and were heavier than broilers fed phytase B. Tibia ash was lowest in broilers fed the low-avP diet and highest in broilers fed the diet supplemented with mono-dicalcium phosphate. Phytase increased tibia ash, and broilers fed phytase A had an increase in tibia ash compared with broilers fed phytase B. In conclusion, high dietary phytate reduced broiler performance. Phytase A and phytase B improved bone ash and growth performance, especially in the high-phytate diets. However, phytase A was more efficacious than phytase B, regardless of the level of phytate.     

The response of broilers to the feeding of mash or pelleted diets containing maize of varying particle sizes

1. The effects of maize particle size and steam pelleting on growth and nutrient utilisation were studied with broiler chicks. 2. The presence or absence of 10 microg/kg of 1,25 dihydroxycholecalciferol in diets adequate or deficient in phosphorus was also investigated. Food efficiency was superior with the fine maize diets but calcium retention and phytate phosphorus retention were greatest with the coarse maize diets. Pelleting improved food efficiency and growth in both experiments while phytate phosphorus utilisation was decreased. 3. Addition of 1,25-dihydroxycholecalciferol to the diet increased 16-d body weight, bone ash, plasma dialysable phosphorus and retentions of total phosphorus and phytate phosphorus while decreasing phosphorus deficiency rickets and tibial dyschondroplasia. 4. There were significant interactions between maize particle size and food form. The improvement in calcium retention observed with the coarse maize diets was reduced when the diets were pelleted. When fed as a mash, coarse maize diets resulted in increased plasma dialysable phosphorus levels but when the diet was pelleted this response was eliminated. 5. There was also a significant interaction between particle size and phosphorus concentration in that chicks given diets deficient in phosphorus had improved bone ash when fed coarse maize as compared to fine maize. However, this response was eliminated when the diets were adequate in phosphorus. 6. In one experiment, fine maize diets had higher metabolisable energy values and there was a significant interaction between maize particle size and food form as pelleting improved the metabolisable energy value of coarse maize diets but not fine maize diets. In another experiment only pelleting of the factors studied improved the metabolisable energy value of the diets.     

木聚糖酶对肉仔鸡后肠道微生物的影响

主要研究了小麦基础口粮添加木聚糖酶对肉仔鸡后肠道微生物的影响.将120只7日龄肉仔鸡分成2组,日粮分别添加0,0.1%木聚糖酶,饲喂至21日龄,研究木聚糖酶对肉仔鸡后肠道菌群数量变化的影响.结果表明,加酶未使同肠和盲肠乳酸杆菌、双歧杆菌和大肠杆菌数量发生显著变化.利用变性梯度凝胶电泳技术研究了木聚糖酶对肉仔鸡后肠细菌群体的影响.结果表明,加酶组回肠和盲肠的图谱比对照组条带相对较多,但差异不显著;组内个体间的图谱相似性比组问的相似性相对较大.木聚糖酶影响肉仔鸡后肠微生物数量和种群的作用效果不明显.