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International Journal of Poultry Science 2 (1): 1-6, 2003
© Asian Network for Scientific Information 2003
In ovo Peptide YY Administration and Jejunal Glucose Transport in
Hatchling Turkey Poults:Effects of Dosage and Genotype
B. A. Coles1, J. Croom1*, L. R. Daniel1, V. L. Christensen1 and I. L. Taylor2
1Department of Poultry Science, North Carolina State University,
Raleigh, NC 27695, USA
2School of Medicine, Tulane University, New Orleans, LA 70112, USA
E-mail: wjcroomjr@aol.com
Abstract:
Two trials were conducted to investigate the efficacy of in ovo administration of various dosages of peptide YY (PYY) on jejunal glucose absorption in hatchling poults from two strains of turkeys, Egg Line (EL) selected for egg production and British United Turkey (BUT) selected for growth. In both trials, either 100 µl saline (1.025% w/v) or saline plus PYY were injected into the air cell of fertile EL and BUT line eggs at day 25 of incubation. At hatch, poults were euthanized by cervical dislocation, the jejunum removed and its weight and unstretched length recorded. Two to 4 mg cross-sections of the mid-jejunum were used to estimate active and passive glucose absorption using the accumulation of 3-O-methy-D-glucose (3OMG) in the presence and absence of phlorizin. In Trial 1, EL and BUT eggs were administered saline or saline plus 600 µg/kg egg wt, while in Trial 2, EL and BUT eggs were administered either saline or saline plus 300, 600, or 900 µg/kg egg wt. No differences were observed in hatchling body weights of poults from saline and PYY treated eggs from either line in both trials. In Trial 1, poults from EL treated eggs (600 µg/kg egg wt) had greater active jejunal 3OMG uptake compared with saline treated controls (332 vs. 270 pmol/min/mg tissue, p<0.05, respectively). In Trial 2, poults from BUT eggs treated with 900 µg PYY/kg egg wt had greater (p<0.05) jejunal glucose transport than by the control group or the 600 µg PYY/kg egg wt group. Poults from EL eggs treated with PYY had non-significant increases in 3OMG uptake at all levels of PYY administration. BUT poults from eggs treated with 900 µg PYY/kg had heavier jejunums adjusted for body weight. In ovo PYY administration at day 25 of incubation increases active glucose transport in the intestinal tract of turkey poults, however, response and dosage varies with turkey line.
Key Words: Genotype, glucose absorption, in ovo, intestinal, peptide, PYY, turkeys
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International Journal of Poultry Science 2 (1): 7-14, 2003
© Asian Network for Scientific Information 2003
Physiological Factors Associated with Weak Neonatal
Poults (Meleagris gallopavo)
Vern L. Christensen, Debbie T. Ort and Jesse L. Grimes
Department of Poultry Science, College of Agriculture and Life Sciences,
North Carolina State University, Raleigh, North Carolina 27695-7608, USA
E-mail: vern_christensen@ncsu.edu
Abstract:
Management related deaths in turkey hatchlings remain a problem for turkey growers. The etiologies of such deaths also remain obscure. The hypothesis proposed by the current study was that weak poults identified by their characteristic flip-over behavior would differ physiologically from normal poults in a way that interferes with development of critical systems such as the cardiovascular and nervous system. Eight groups of 500 poults (from a 20-wk laying cycle) of the same breeder flock were examined. Each placement was in the same brooder house operated at identical conditions. Observations of "flip-over" poults were made at 6-h intervals for the initial wk of age. Identified poults (n = 12) were sacrificed and sampled immediately. Flip-over poults differed from controls only in depressed heart weight and plasma thyroid hormone concentrations. The identified poults did not differ from controls in body weight, liver weight, yolk weight, blood glucose or organ glycogen concentrations. In a second trial, reduced heart weights were noted along with reduced capability to maintain cardiac glycogen concentrations. The reduced heart weight or function may result in failure to provide nutrients for proper brain function. The data suggest that management to aid weak neonatal turkey poult deaths may need to focus on conditions fostering heart growth and function.
Key words: Flip-over, weak poults, heart, thyroid
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International Journal of Poultry Science 2 (1): 15-18, 2003
© Asian Network for Scientific Information 2003
Evaluation of Crude Protein Needs for Large White Male Turkeys
from 16 to 20 Weeks of Age
P. W. Waldroup1, C.A. Fritts1, J. H. Kersey1, E. A. Saleh1, B. J. Kerr2 and M.T. Kidd2
1Poultry Science Department, University of Arkansas, Fayetteville AR 72701, USA
2Nutri-Quest, Inc., Chesterfield MO 63017, USA
E-mail: Waldroup@uark.edu
Abstract:
A study was conducted to determine the minimum crude protein content of finisher diets based on corn and soybean meal supplemented with commercially available amino acids for male Large White turkeys. Diets were formulated to contain a minimum of 105% of NRC (1994) recommended levels of Met, Lys, TSAA, Thr, and Trp for diets fed 16 to 20 wk of age; no other essential amino acids were specified. The crude protein content of the diets ranged from 75 to 100% of the recommended level of 16.5%. When diets were formulated to contain at least the minimum recommended levels of Met, TSAA, Lys, Thr, reducing the crude protein content of the diet to less than 85% resulted in a significant reduction in weight at 20 wk or body weight gain from 16 to 20 wk. Addition of Ile and Val to diets formulated to contain 80 or 85% of the recommended crude protein level had no significant effect on body weight or weight gain, indicating that a deficiency of these amino acids per se was not responsible for the reduction in performance on diets with low levels of crude protein. Feed conversion was more variable and was not significantly influenced by dietary crude protein.
Key words: Turkeys, amino acids, crude protein, requirements
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International Journal of Poultry Science 2 (1): 19-22, 2003
© Asian Network for Scientific Information 2003
Evaluation of Bio-Mos® Mannan Oligosaccharide as a Replacement
For Growth Promoting Antibiotics in Diets for Turkeys
C. A. Fritts and P. W. Waldroup
Poultry Science Department, University of Arkansas, Fayetteville, AR 72701, USA
E-mail: Waldroup@uark.edu
Abstract:
A study was conducted to evaluate the use of Bio-Mos®, a mannan oligosaccharide derived from the cell wall of yeast, as a potential replacement for growth promoting antibiotics in the diet of growing turkeys. Bio-Mos® was added to nutritionally complete turkey diets at the rate of 0.05 and 0.10%. The growth-promoting antibiotics bambermycins and bacitracin methylene disalicylate (BMD) were added at 2.2 and 55 mg/kg, respectively. One group was fed the diet with no supplements and served as the negative control. Male turkeys of a commercial Large White strain were fed the test diets from day old to 20 wk of age. Birds were weighed at intervals through the trial and samples of birds processed at 20 wk for parts yield and determination of intestinal breaking strength. Body weight, mortality, breast meat yield, and intestinal breaking strength were not significantly (P < 0.05) influenced by dietary treatments. Feed conversion from 0 to 20 wk of age was significantly improved by both BMD and 0.10% Bio-Mos®. The addition of BMD significantly reduced the percentage of abdominal fat in the carcass. These results suggest that Bio-Mos® might be considered as a part of an overall feeding and management program to aid in overcoming potential loss of growth-promoting antibiotics.
Key words: Mannan oligosaccharide, Bio-Mos®, antibiotics, turkeys
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International Journal of Poultry Science 2 (1): 23-27, 2003
© Asian Network for Scientific Information 2003
Alloantigen System L Affects Antibody Responses
Zdravka O. Medarova1, W. Elwood Briles2 and Robert L. Taylor, Jr.*1
1Department of Animal and Nutritional Sciences, University of New Hampshire,
Durham, NH 03824, USA
2Department of Biological Sciences, Northern Illinois University, DeKalb, IL 60115, USA
E-mail: bob.taylor@unh.edu
Abstract:
Alloantigen system L is a polymorphic protein expressed on the surface of chicken erythrocytes and possibly certain leukocyte subpopulations. Previous studies demonstrated that the L system affects Rous sarcoma outcome and phagocytic function. The present experiments examined the L system influence on antibody responses to two antigens: SRBC (T-dependent) and Brucella abortus (BA, partially T-independent) in three B complex genotypes. The parental stock were 50% Modified Wisconsin Line 3 x White Leghorn Line NIU 4 and 50% Inbred Line 6-15.5. Pedigree matings of 4 B2B5L1L2 sires to 5 B2B5L1L2 dams per sire produced three hatches (n = 183) for the antibody response to SRBC and two hatches (n = 198) to study antibody response to BA. At 4 and 11 weeks of age the experimental birds were injected intravenously with 1 mL of 2.5% SRBC or 0.1 mL of 10% BA. Total and mercaptoethanol (ME)-resistant primary and secondary titers were analyzed by least squares ANOVA. Alloantigen L had a significant effect on total primary antibody titer to SRBC in a B5B5 background (p < 0.004) and on total (p < 0.011) and ME-resistant (p < 0.017) secondary titer to SRBC in the B2B5 genotype. Total (p < 0.004) and ME-resistant (p < 0.005) secondary titers to BA in B2B5 chickens were significantly affected by alloantigen L. The data indicate that the alloantigen L locus or genes in the immediate chromosomal vicinity affect antibody responses to SRBC and BA.
Key words: Erythrocyte alloantigen, major histocompatibility (B) complex, L alloantigen, Brucella abortus
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International Journal of Poultry Science 2 (1): 28-31, 2003
© Asian Network for Scientific Information 2003
Comparison of Bio-Mos® and Antibiotic Feeding Programs in Broiler
Diets Containing Copper Sulfate
P. W. Waldroup, Edgar O. Oviedo-Rondon and C. A. Fritts
Poultry Science Department, University of Arkansas, Fayetteville AR 72701, USA
E-mail: Waldroup@uark.edu
Abstract:
A study was conducted to evaluate the response of broilers to diets containing a mannan oligosaccharide, antibiotics, or a combination of antibiotics and mannan oligosaccharide. All diets were supplemented with copper sulfate to provide 250 mg/kg Cu in diets fed to 42 d and 62.5 mg/kg Cu in diets from 42 to 56 d, in addition to the 10 mg/kg provided in the trace mineral mix. Bio-Mos®, a mannan oligosaccharide derived from the cell wall of the yeast Saccharomyces cerevisiae, was added at 1 g/kg in diets fed to 42 d and at 0.75 g/kg in diets fed 42 to 56 d. The antibiotic program consisted of 55 mg/kg of bacitracin methylene disalicylate to 42 d of age followed by 16.5 mg/kg virginiamycin to 56 d of age. When the Bio-Mos® and antibiotics were fed in combination, half the levels indicated above were fed. Twelve pens of 50 male broilers were fed each of the dietary treatments. Results of the study indicate that body weight of broilers was not significantly influenced by the antibiotic treatment, addition of Bio-Mos®, or the combination of antibiotics and Bio-Mos®. Feed conversion at 42 d was significantly improved by both the antibiotic treatment and by the addition of Bio-Mos®. At 56 d the feed conversion of birds fed the antibiotics or the combination of antibiotics and Bio-Mos® was improved compared to that of birds fed the negative control (P = 0.10). No significant effects on mortality, dressing percentage, or parts yield were observed. Possible interference of copper sulfate with the activity of the antibiotics and Bio-Mos® is discussed.
Key words: Mannan oligosaccharide, broilers, antibiotics, copper sulfate, growth promotion
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International Journal of Poultry Science 2 (1): 32-37, 2003
© Asian Network for Scientific Information 2003
Evaluation of Dietary Calcium Level and Fat Source on Growth Performance
and Mineral Utilization of Heat-distressed Broilers
M. O. Smith1, K. Soisuvan2 and L. C. Miller1
1Department of Animal Science, The University of Tennessee, 2640 Morgan Circle,
Knoxville, TN 37996-4588, USA
2Department of Animal Science, Kasetsart University, Bangkok, Thailand
E-mail: mosmith@utk.edu
Abstract:
Male broilers (commercial strain) were used to evaluate the effects of diets differing in fat source on performance of heat-distressed broilers. Dietary treatments included corn oil (CO), animal fat (AF), fish oil (FO) and a dry blended (animal and vegetable) fat product (DB) at either 0.9 or 1.5 % calcium. Diets were isocaloric with each containing an equal number of calories from fats. Birds were reared in floor brooder pens and fed experimental diets from Day 1 to 21 and then assigned the same dietary treatments in one of two environmentally controlled chambers. One chamber was maintained at 23.9 oC, whereas birds in the second chamber were exposed to 8 hours of 23.9 oC, 4 hours of 23.9 to 35 oC, 4 hours of 35 oC and 8 hours of 35 to 23.9 oC. At 42 days of age, plasma concentration of calcium and magnesium were higher (p > 0.01) in heat distressed (HD) birds than in their thermoneutral (TN) counterparts. Dietary calcium level, but not fat source, affected plasma calcium concentration. Temperature significantly (p < 0.05) affected the relative mineral retention (feed minus fecal mineral content) of magnesium while relative mineral retention of copper was affected by fat source. There was no effect of calcium level on performance but HD birds gained 31 % less weight than TN. Birds fed AF gained 10 % more than FO and 14 % more than DB. Data suggest that both fat source and environmental temperature influence mineral utilization and body weight gain.
Key words: Broilers, heat distress, dietary fats, fatty acids, mineral retention
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International Journal of Poultry Science 2 (1): 38-43, 2003
© Asian Network for Scientific Information 2003
Digestible Sulfur Amino Acid Requirement of Male Turkeys
During the 12 to 18 Week Period
D. T. Moore, K. Baker, K. Thompson, E. Blair and J. D. Firman
University of Missouri-Columbia, 116 Animal Sciences Department,
Columbia, MO 65211, USA
Email: FirmanJ@missouri.edu
Abstract:
Two floor pen trials were conducted to determine the digestible sulfur amino acid (SAA) requirement of male turkeys for the periods of 83 to 92 days and 106 to 116 days. The experiments were designed using 48 pens allowing eight treatments of six replicate pens using a randomized block design. For the 83 to 92 day period, 192 toms were sorted by weight and assigned a treatment. Digestible SAA levels ranged from 3.5 to 5.9 g/kg of diet. For the 106 to 116 day period, 144 toms were sorted by weight and assigned a treatment. Digestible SAA levels ranged from 3.0 to 5.0 g/kg of diet. These levels were obtained by titrating synthetic methionine into a low protein diet. The other synthetic amino acids were added back to the low protein diet at levels sufficient to provide growth similar to a positive control diet. The positive controls for the periods were standard corn, soybean meal, and meat meal diets based on NRC (1994) recommendations. Performance parameters measured for the trial were body weight gain and feed conversion. Parts yield of birds on the second trial were also taken with no significant differences between SAA levels found. The data were analyzed by analysis of variance followed by splined regression analysis. The digestible SAA requirements for body weight gain and feed conversion of male turkeys are 3.9 and 4.0 g/kg for the 83 to 92 day period and 3.7 and 3.4 g/kg for the 106 to 116 day period, respectively.
Key words: Turkey; amino acid; methionine; cysteine
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International Journal of Poultry Science 2 (1): 44-52, 2003
© Asian Network for Scientific Information 2003
Utilization of Bio-Mos® Mannan Oligosaccharide and Bioplex®
Copper in Broiler Diets
P. W. Waldroup, C. A. Fritts and Fenglan Yan
Poultry Science Department, University of Arkansas, Fayetteville, AR 72701, USA
Email: Waldroup@uark.edu
Abstract:
A study was conducted to evaluate the effects of combinations of antibiotics, mannan oligosaccharides, and organic forms of copper in the diet of broilers. Male broilers in litter floor pens were fed nutritionally complete diets with a 2 x 2 x 3 arrangement of treatments including two antibiotic programs (none; 55 mg/kg bacitracin methylene disalicylate from 0 to 42 d followed by 16.5 mg/kg virginiamycin to 63 d), two levels of mannan oligosaccharide (none; 1 g/kg Bio-Mos® from 0 to 42 d followed by 0.75 g/kg to 63 d) and three copper programs (none; copper sulfate to provide 250 mg/kg from 0 to 42 d followed by 62.5 mg/kg to 63 d; Bioplex® Cu to provide 55 mg/kg from 0 to 42 d followed by 27.5 mg/kg to 63 d). This resulted in a total of 12 experimental treatments, each fed to eight pens of 50 male chicks. Birds and feed were weighed at intervals during the study and samples of birds processed at 63 d to determine dressing percentage and parts yield. Body weight and feed conversion at 21 d was significantly improved by addition of the antibiotics but did not prove to be significantly improved at later ages. Addition of copper from either copper sulfate or Bioplex® Cu had no significant effect on any parameter tested. Addition of Bio-Mos® at the levels tested had no significant effect on any parameter but did interact with some of the other factors. Carcass characteristics were not improved by any of the factors tested. It is possible that the level of Bio-Mos® used in this study was not sufficient to elicit a positive response.
Key words: Copper, mannan oligosaccharides, antibiotics, broilers
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International Journal of Poultry Science 2 (1): 53-57, 2003
© Asian Network for Scientific Information 2003
The Effect of Beak Length and Condition on Food Intake and
Feeding Behaviour of Hens
P. C. Glatz
Pig and Poultry Production Institute, South Australian Research and Development Institute,
Roseworthy, South Australia, Australia 5371
E-mail: glatz.phil@saugov.sa.gov.au
Abstract:
Hens (70 weeks-of-age) with short (10-11 mm), long (13-15 mm) and divided upper beaks (1-3 mm difference in beak length between the left and right sides of the upper beak) were selected from a flock of hens beak trimmed at hatching and re-trimmed at 14 weeks. Hens were switched from a mash diet to various whole grain diets at weekly intervals in order to determine the effect of beak length and condition on food intake, feeding behaviour and particle mix consumed from diets. Birds switched from a mash diet to a mixture of whole grain diets suffered a 22.6 g/day drop (P<0.05) in food intake while, conversely, birds changed from a maize and wheat diet to a sorghum and wheat diet had a 28.4 g/day increase (P<0.05) in food intake. For all diets, birds with short upper beaks consumed 7.8 g/day less (P<0.05) than birds with long upper beaks with divided beak birds intermediate in food intake. Feeding rate of divided beak birds (4.0 mg food/sec) was significantly (P<0.05) less than short beak birds (5.3 mg food/sec) with long beak birds intermediate (5.0 mg food/sec). Birds with a short upper beak made significantly (P<0.05) more pecks at the water nipple than divided beak birds. These studies demonstrated that beak condition of layers has important implications for egg farmers. The performance of birds with short upper beaks might be adversely affected when fed free choice or whole grain diets.
Key words: Laying hens, beak trimming, beak length, particle size, feeding behaviour
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International Journal of Poultry Science 2 (1): 58-61, 2003
© Asian Network for Scientific Information 2003
Blend of Bovine Blood and Rumen Digesta as a Replacement for
Fishmeal and Groundnut Cake in Layer Diets
A. A. Odunsi
Department of Animal Production and Health, Ladoke Akintola University of Technology,
P. M. B 4000, Ogbomoso, Nigeria
E-mail: yodunsi@yahoo.com
Abstract:
The mixture of bovine blood and rumen digesta (BBRDM) was evaluated as a replacement for groundnut cake (GNC) and fishmeal (FM) in the diets of layer chickens. Five diets were formulated in which diet 1 served as the control diet (CD) without BBRDM. Diets 2 and 3 contained 5 and 10 % BBRDM replacing 28 and 56% respectively of the GNC in the CD. Diets 4 and 5 contained BBRDM at 5 and 10% replacing 50 and 100% of the FM also in the CD. Each diet was offered to 18 layers (36 weeks old) divided into three equal replicates for a period of 8 weeks. On analysis, BBRDM contained 46.1% crude protein, 2.13% ether extract, 6.38% crude fibre, 23.4% ash and 16.02% nitrogen free extractive. Results indicated significantly lower (p<0.05) feed intake, hen-day egg production, egg weight and shell thickness in birds fed BBRDM based diets with a worsened feed/egg ratio compared to the CD. Haugh unit and yolk index were however, enhanced (p<0.05) with the use of BBRDM. Feed cost per kg egg was reduced in diets in which BBRDM replaces FM while this parameter increased for GNC. Net returns were raised by 4 and 10% in FM diets whereas negative returns were recorded for GNC. The profit-maximizing objective of table egg production is achievable by BBRDM utilization in layer feed as a replacement for FM and not for GNC. Results suggested that in the form fed, BBRDM should be cautiously used and that layers fed diets in which FM was replaced gave a better performance compared to those involving GNC.
Key words: Bovine blood, rumen digesta, feedstuff, layers, nutrition
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International Journal of Poultry Science 2 (1): 62-70, 2003
© Asian Network for Scientific Information 2003
Performance of Broiler Chickens on Commercial Diets Mixed with Whole or Ground Wheat of Different Varieties
Sulhattin Yasar
Department of Animal Science, Faculty of Agriculture,
University of Suleyman Demirel, Isparta 3200, Turkey
E-mail: sulhattiny@yahoo.com
Abstract:
To study the effects of mixing commercial diets with whole wheat on bird performance with respect to growing ages, each of four whole or ground wheat varieties was mixed with commercial diets at the presence or absence of enzyme at the following rates: 10% from 7 to 14 d of age, 20% from 14 to 21 d of age, 30% from 21 to 28 d of age, and 50% from 28 to 35 d of age. A control group of broiler chickens was fed only with commercial diets throughout. Birds performed well with the diets mixed with 10 and 20% wheat whether ground or whole. Feed intake of birds significantly (P<0.05) depressed only by the diets mixed with 50% of both whole and ground wheat. Weight gain and feed conversion ratio significantly (P<0.05) reduced with the diets mixed with 30 and 50% whole and ground wheat. There were no significant effects of wheat variety, wheat form and enzyme addition on the bird performance. Enzyme did not improve the performance of birds fed with the diets containing whole or ground wheat although there was a significant reduction in the digesta viscosity. Gut length was significantly longer in the birds fed on all the diets mixed with ground or whole wheat than the birds of control diets. It is concluded that birds can control feed intake unless they are not fed with the 50% wheat mixed diet until 28 d of age and grow optimally unless they are not fed with the 30% wheat mixed diet from 21 to 28 d of age. Furthermore, it is suggested that the fortification with some essential nutrients is necessary at early growing ages when mixing the diets with whole/ground wheat at high rates of <30%.
Key words: Broiler chickens, whole wheat, wheat variety, enzyme, viscosity
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International Journal of Poultry Science 2 (1): 71-74, 2003
© Asian Network for Scientific Information 2003
Assessment of Lablab (Lablab Purpureus) Leaf Meal as a Feed Ingredient
and Yolk Colouring Agent in the Diet of Layers
A. A. Odunsi
Department of Animal Production and Health, Ladoke Akintola University of Technology,
P. M. B 4000, Ogbomoso, Nigeria
E-mail: yodunsi@yahoo.com
Abstract:
A feeding experiment was conducted to determine the performance, nutrient digestibility and egg quality of layers fed 0,50, 100 or 150 g/kg leaf meal of Lablab purpureus (lablab) Chemical analysis of lablab gave (g/kg) crude protein 234.0, ether extract 19.0, crude fibre 83.4, ash 116.0 and nitrogen free extracts 467.0. Feeding lablab at 100 and 150 g/kg significantly reduced feed intake and egg production while egg weight, feed conversion efficiency and body weight changes were not affected (p>0.05) by dietary treatments. Apparent nutrient digestibility of dry matter and crude protein decreased significantly (p<0.05) with lablab while ether extract was not significantly influenced. Internal and external egg quality values were comparable amongst dietary groups except for yolk colour, which was significantly higher (p<0.05) in layers fed lablab compared to those without. Diet and boiling had no significant effect (p>0.05) on the proportion of egg components but boiling effected a percentage reduction of 62, 56 and 52 in the egg yolk colour of 50, 100 and 150 g/kg lablab fed layers respectively. The persistence of the colour change after withdrawal of lablab ranged from 5 days (50 g/kg) to 15 days (150 g/kg). Based on egg quality, lack of mortality and similar biological efficiency, it may be possible to include lablab in layer diets up to 100 and 150 g/kg in situations of acute scarcity and/or high cost of grain and concentrates.
Key words: Lablab leaf meal, layers, yolk colour, nutrient digestibility
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International Journal of Poultry Science 2 (1): 75-82, 2003
© Asian Network for Scientific Information 2003
Performance, Gut Size and Ileal Digesta Viscosity of Broiler Chickens Fed with a Whole Wheat Added Diet and the Diets with
Different Wheat Particle Sizes
Sulhattin Yasar
Department of Animal Science, Faculty of Agriculture,
Suleyman Demirel University, Isparta, Turkey
E-mail: sulhattiny@yahoo.com
Abstract:
To evaluate the effect of various particle sizes of wheat grain in meat-type birds, the performance and gut response of birds to 4 starter diets containing 30% and 4 finisher diets containing 50% wheat grain of different particle sizes passed through 4, 5, 6 and 7 mm sieves were compared with the responses of birds to whole wheat addition in a starter and a finisher diet at the same rates. The dietary treatments were as follows: fine texture (F) for wheat sieved by 4 mm, medium texture 1 (M1) for 5 mm sieved wheat, medium texture 2 (M2) for 6 mm sieved wheat, coarse texture (C) for 7 mm sieved wheat and whole (W) for whole wheat. All diets were isocaloric and isonitrogenous, and all other main dietary ingredients except wheat were ground to pass 5 mm sieve. The performance parameters were feed intake, weight gain and feed conversion ratio from 0 to 42 d. In vivo viscosity of ileal digesta, fresh lengths and weights of whole digestive tract and the amount of abdominal fat were also determined for all treatments. The results revealed that the best performance was obtained from the C diets, the F diet resulted in the lowest performance and those resulting from the M1, M2 and W were intermediate. However, the worsened performance induced by F and W starter diets of 30% wheat up to 21 d old was statistically become insignificant at later ages with finishing diets of 50% in comparison with the M1, M2 and C diets, suggesting that particle size of wheat grain lead to significant changes in bird's performance at early starting and growing periods, but not during the finishing periods even though the rate of wheat in the diet was increased from 30 to 50%. The diet of fine wheat particle resulted in significantly higher ileal digesta viscosity than the coarse and whole wheat added diets at both 21 d and 42 d old. It is most likely that increased digesta viscosity and changes in gut size can induce significant changes in the performance of broiler chickens, especially when the birds were young. In short, feeding broiler chickens with fine texture of wheat grain at early growing periods is not suggested due to the increased ileal viscosity and depressed performance although the negative effects of fine texture of wheat grain were overcome during finishing period even with 50% wheat additions. Medium and coarse texture of wheat grain remained to be the most preferred form of cereal grains although the whole grain is of great importance when no cost is considered for grinding.
Key words: Particle size, whole wheat, digesta viscosity, gut size, broiler chickens
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