The effects of fructo-oligosaccharides or whole wheat on the performance and digestive tract of broiler chickens

1. The objective of this experiment was to study two feeding methods, which could potentially act on the gut microflora, the structure and/or the function of the digestive tract and thereby improve the performance of broilers. 2. Four dietary treatments were studied: a negative control (wheat based) with no additives (C), a positive control with 0.01 g/kg avilamycin (AV), a treatment with 0.6 g/kg fructo-oligosaccharides (FOS) and a treatment with the same composition as treatment C but in which a part or all (400 g/kg) of the wheat was given as whole wheat and a concentrate supplement (WW). The measurements were: the performance from 0 to 6 weeks, the bacterial counts at 3 and 6 weeks, the digestive tract morphology and the activity of some intestinal enzymes at 3 weeks. 3. The birds given AV had better daily live weight gain (DLWG) and feed conversion ratio (FCR) compared to treatment C. The birds given FOS had a lower feed intake and a lower DLWG than the birds on treatment C but their FCR was significantly improved. WW resulted in a numerically lower feed intake and a significantly lower DLWG than treatment C. With AV, the number of aerobic mesophilic bacteria in the caeca was reduced at 3 weeks. With WW, gizzard and pancreas weights were greater and the surfaces of the ileal crypts were larger. An increased activity of leucine aminopeptidase (LAP) in the duodenum was found for treatments AV, FOS and WW. 4. In conclusion, in this study, treatments WW and FOS reduced DLWG, which may have been due to a lower feed intake during the whole period. With WW, the FCR was not affected, maybe because of both positive and negative effects on digestive tract (higher gizzard and pancreas development and LAP activity; larger crypts). However, FOS improved FCR, which may be partly explained by the higher LAP activity.     

Differences in the digestive tract characteristics of broiler chickens fed on complete pelleted diet or on whole wheat added to pelleted protein concentrate

1. The effects of whole grains of wheat on the digestive tract of broiler chickens was studied. A complete pelleted feed was compared with free choice feeding of whole wheat and a pelleted protein concentrate, given from 7 to 29 d of age. 2. Pepsin activity in proventriculus tissue was lower in whole wheat-fed birds than in complete diet-fed birds. The weight (g/kg body weight) of the gizzard was higher in whole wheat-fed birds and its contents had a lower pH. 3. In the intestine, there were no differences in deoxyribonucleic acid (DNA) concentration, protein/DNA, ribonucleic acid (RNA)/DNA, RNA/protein ratios or alkaline phosphatase activity expressed per tissue weight. The weight (g/kg body weight) of the duodenum was lower in whole wheat-fed birds and its contents had a higher pH. Also the activities of alkaline phosphatase and leucine aminopeptidase in the duodenum, and maltase in the ileum, expressed per unit of bird weight, were lower in whole wheat-fed birds. 4. These results suggest that whole grain feeding increases the chemical (pepsin in proventriculus) and physical (gizzard muscle) functionality of the upper part of the digestive tract but decreases the digestive capacity of the intestine. Higher gizzard functionality may play a positive role in the control of bacterial populations. The lower digestive enzyme activities in the intestine may be detrimental in situations of mucosal deterioration caused by intestinal disease.     

Comparison of performance and intestinal characteristics of broiler chickens fed on diets containing whole,rolled or ground barley

1. In two experiments, no consistent differences in weight gain or food intake appeared between broiler chickens given diets based on whole or rolled barley, but food: gain ratio and gizzard weight as a percentage of live weight were reduced (P<0.05) when barley was rolled. Grit addition did not affect performance or intestinal characteristics.

2. In a third experiment, whole barley diets gave significandy higher weight gain than ground barley diets; this was attributable to the significandy higher food consumption. Gizzard weight as a percentage of live weight increased (P< 0.05) when whole barley was fed, while foodrgain ratio was not significandy (P>0.05) affected by the form of barley.

3. The number of particles in the intestinal contents with sizes larger than 2.4 mm was not significantly (P<0.05) different between broiler chickens fed on whole barley and those fed ground barley, but the number of particles with sizes between 2.4 and 0.7 mm was lower (P< 0.05) when diets with whole barley were fed.

4. Enzyme addition increased (P< 0.05) weight gain and the DM of intestinal contents, and decreased (P<0.05) intestinal viscosity, food:gain ratio and pancreas weight as a percentage of live weight regardless of form of the barley.     

Causes for improvement in nutritive value of broiler chicken diets with whole wheat instead of ground wheat

1. Two experiments were conducted with broiler chicks to compare nutritive values of ground and whole wheat diets containing titanium oxide as indigestible marker. 2. In Experiment 1, a wheat and soy isolate based cold-pelleted diet, in which all the wheat was ground in a hammer mill to pass through a 3 mm sieve, was compared with a diet in which about half (375 g/kg) of the ground wheat was taken out of the diet and supplied as whole wheat mixed into the diet after pelleting. 3. In Experiment 2, a diet based on ground wheat and soy isolate which was pelleted after preconditioning (final temperature 81 degrees C) was compared with a diet in which 500 g of the ground wheat was replaced by whole wheat mixed into the diet before pelleting. 4. In Experiment 1, replacement of ground wheat with whole wheat increased apparent metabolisable energy (AME) content and starch digestibility measured at ileal as well as faecal level, while weight gain and feed conversion efficiency (FCE) were not affected. Jejunal chyme showed increased amylase activity and bile salt concentration. 5. In Experiment 2, replacement of ground wheat with whole wheat increased dry matter content as well as bile content of gizzard, and stimulated an increase in gizzard as well as pancreas weight. Jejunal amylase and bile concentrations were not significantly affected and neither were growth, FCE or AME. 6. Results from this experiment indicate that the improved feed value sometimes observed with whole wheat may be associated with modulation of digestive processes resulting in increased pancreas and liver secretions.     

Nutrient digestibility and intestinal viscosities in broiler chickens fed on wheat diets, as compared to maize diets with added guar gum

1. Three maize diets containing 0, 1 or 3 g of guar gum per kg and 2 wheat diets were given to male broiler chickens for measurements of growth performance and nutrient digestibility. 2. The intestinal viscosities found with wheat diets were within the range of those observed with the 3 maize diets. The correlations between in vivo and in vitro viscosities were higher with real than with potential applied viscosity. 3. The gain:food ratio decreased (P < 0.05) with the addition of 3 g guar gum/kg. The mean gain:food ratio observed for wheat diets was lower (P = 0.007) than the mean value found for the 3 maize diets. 4. The negative effects of increased intestinal viscosity due to guar gum addition on nutrient digestibility were highest for lipids and lowest for starch. 5. Wheat diets resulted in much lower (P < 0.001) starch apparent digestibility compared to maize diets with added guar gum despite similar mean intestinal viscosities in the 2 groups of diets. Apparent lipid digestibility with wheat diets was lower (P < 0.01) than the value predicted from intestinal viscosity, the predictive model having been calculated with the guar gum added maize diets. Apparent protein digestibility did not differ between wheat diets and guar gum added maize diets. 6. It was concluded that the low apparent digestibilities of starch and lipid observed with wheats could not be attributed only to intestinal viscosity and that other factors appear to be implicated in the low digestibilities observed with the wheat samples tested in the present experiment.     

Growth performance,carcass traits and digestive function of broiler chickens fed diets with graded levels of corn resistant starch

ABSTRACT

1. This study was conducted to assess the effects of graded levels of dietary corn resistant starch (RS) on growth performance, carcass traits, nutrient retention, digestive organ index, intestinal morphology, digestive enzyme activities, and mRNA expression of certain nutrient transporters in broiler chickens.

2. A total of 320, 1-d-old Arbor Acres broiler chickens were randomly assigned to five dietary treatments, with eight replicates of eight birds in each. These treatments included one corn-soybean control diet, a corn-soybean based diet containing 20% corn starch, and three diets supplemented with 4%, 8% and 12% RS by replacing corn starch with 6.67%, 13.33% and 20% of Hi-Maize 260® (identified as control, RS1, RS2, RS3 and RS4, respectively). The feeding period lasted 42 days.

3. Performance parameters including feed consumption, feed conversion, body weight gain and percentage of abdominal fat at d 42 of age, nutrient retention (including dry matter, fat, total starch and nitrogen free extract), and apparent metabolisable energy was measured from d 18 to 20 and d 39 to 41 and showed negative linear responses to increasing dietary RS level (P < 0.05). Birds fed the RS3 and RS4 diets showed higher relative weight of duodenum, jejunum and ileum, as well as lower villus height and villus height/crypt depth compared to the control (P < 0.05). The activity of pancreatic trypsin of birds at d 21 and 42 of age decreased linearly in response to the increase of dietary RS level (P < 0.01). There were linear changes in up-regulated mRNA expression of SGLT-1 and down-regulated mRNA expression of GLUT-2 with increasing proportion of RS at d 21 and 42 of age (P < 0.05), respectively.

4. It was concluded that feeding broilers with diets containing higher concentrations of RS impaired the development of small intestine, which resulted in lower apparent total tract retention of nutrients and poorer body weight gain, feed efficiency and carcass traits of broiler chickens.     

Sequential feeding of whole wheat to growing broiler chickens

1. Four broiler feeding trials were performed to examine the suitability of a whole wheat sequential feeding regimen for commercial broiler production. The sequential feeding programme gave a continuous cycle of ad libitum access to only whole wheat followed by the same time of access to only a pelleted diet. The pelleted diet provided a concentration of nutrients to balance that provided by the whole wheat. This was called a balancer diet.

2. The first trial used 144 cage‐reared broilers from 28 to 49 d of age. Four different times of access (4, 8, 12 and 24 h) to the two alternate foods were compared. A whole wheat choice‐feeding treatment and a complete single diet treatment were also compared. Whole wheat accounted for over 40% of the broilers’ total food intakes when they were given the sequential feeding treatments of 8 h or greater. The whole wheat intakes of the birds given the 4 h sequential feeding and the choice‐feeding were only 20 and 5% respectively. There was a non linear relationship between the weight gains of the broilers and the length of the sequential feeding period (P< 0.01). The growth rates of the broilers given sequential feeding were lowest (P< 0.05) in the 4‐h feeding periods but highest (P< 0.05) in the 8‐h periods. Weight gains decreased (P< 0.01) linearly as the sequential feeding periods were increased above 8 h.

3. A second trial, using 144 cage‐reared broilers, examined the effect of different balancer compositions or different wheat varieties in 8‐h sequential feeding. The broilers selected more whole wheat in their diet when they were given balancers with increased cereal contents. However, these broilers did not eat enough whole wheat to compensate for the reduced cereal content of the balancers and their overall diets had lower energy: protein ratios. The two different wheat samples did not result in any differences (P> 0.05) in the proportion of whole wheat selected by the broilers.

4. A third trial compared the diet selections, weight gains, food intakes and water excretions of 72 cage‐reared broilers given whole wheat feeding regimens. The growth rates of the broilers given a loose mix of whole wheat and a pelleted balancer diet were similar (P> 0.05) to broilers given a complete single diet. The growth rates of these two groups were 7% greater (P< 0.05) than broilers given choice‐feeding or 8‐h sequential feeding. There were no differences (P> 0.05) in the total amounts of water excreted among the 4 treatments.

5. The fourth trial used 828 broilers distributed in 6 floor pens. They were given either a complete diet or an 8‐h whole wheat sequential feeding regimen from 25 to 46 d of age. The food intakes and the growth rates of the broilers were reduced (P<0–05) in die sequential feeding treatment by 9% and 5% respectively. There was no difference (P> 005) in litter moisture between the 2 treatments.     

Energy metabolism of cocks and broiler chickens fed on diets with different carbohydrate sources.

Energy balances of cocks and chickens were measured using the nitrogen-carbon-balance method. In Experiment 1 twelve adult White Leghorn cocks were fed alternately on a basal ration or on a supplemental ration composed of 75% basal diet and 25% carbohydrate source as a supplement. In Experiment 2 six groups of 12 male broiler chickens were fed successively on two diets each with different carbohydrate sources (40% of DM) and on two energy levels. The investigated carbohydrate sources were glucose, fructose, sucrose, maize starch, raw and steamed potato starch, dried sugar beet pulp, tapioca, wheat, maize, rye and barley. In both experiments the energy digestibility of the diets with raw potato starch, beet pulp and barley was significantly lower compared to the other diets. Digestibility of those ranged from 88 to 81%. By simple linear regression no significant differences in efficiency of utilisation of ME of the diets between the carbohydrate sources sugars, starches and cereal grains could be proved. The corresponding MEm values agreed very close among the diets (411 to 429 kJ.kg BW-0.75.d-1).     

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.     

The efficiency of energy retention of broiler chickens and turkeys fed on diets with different lysine concentrations

1.?An experiment determined the effect of 6 different lysine concentrations (40, 52, 58, 65, 90 and 130 g/kg CP) in two protein concentrations (210 and 260 g/kg) on the efficiency of energy utilisation of broiler chickens and turkeys. Ninety-six male Ross 308 broiler chicks and 96 male BUT Big 6 turkey poults were fed at 90% of ad libitum during a 12 d bioassay period. At the end of the bioassay, birds were slaughtered and carcase crude protein, fat and gross energy were measured and nutrient metabolisability determined.

2.?Broiler chickens had lower AME and AME_N than turkeys. AME was higher in the 260 g/kg than in the 210 g/kg protein diet; however, no difference was evident in AME_N between any of the diets in both species. A significant species × lysine interaction indicated that the decrease in AME and AME_N with increasing lysine was greater in turkeys than in broiler chickens.

3.?Turkeys had lower weight gains and efficiencies of energy retention than broiler chickens. The effects of different lysine concentrations on growth and the efficiency of energy retention were significant and growth responses were quadratic but there were negative linear responses in the efficiency of energy retention in both species at both crude protein concentrations. The efficiency of energy retention was increased with decreasing lysine concentrations throughout the wide range of concentrations used in the experiment.     

Performance and meat quality of broiler chickens that are fed diets supplemented with Agaricus brasiliensis mushrooms

This trial was performed to study the use of the mushroom Agaricus brasiliensis as an alternative additive to antimicrobial growth promoters in broiler chicken diets and to assess the quality of the broiler chicken breast meat of birds that are fed diets containing this fungus. Thus, 595 1-day-old chicks were reared in reused poultry litter without anticoccidial and antimicrobial additives. The results showed that a concentration of 1.6 g mushrooms/kg diet was ideal for these birds because it provided better bird performance. When the birds’ immune system organs were analyzed, it was found that the addition of both mushrooms influenced the immune system organs of these broiler chickens. Adding A. brasiliensis to broiler chicken diets did not compromise breast meat quality.     

Effects of oat hulls and wood shavings on digestion in broilers and layers fed diets based on whole or ground wheat

1. An experiment was conducted to study the effects of inclusion of oat hulls in diets based on whole or ground wheat for broilers. Effects of wood shavings on layers were investigated in a further experiment. 2. Inclusion of oat hulls in wheat-based broiler diets did not affect weight gain. Feed conversion efficiency (FCE), corrected for insoluble fibre contents, was improved by oat hull inclusion. 3. Gizzard size increased with inclusion of oat hulls, whole wheat, wood shavings and grit. 4. Starch digestibility was significantly increased by inclusion of oat hulls for broilers, and by wood shavings for layers. 5. Wood shavings and whole wheat did not affect bile acid concentration of gizzard contents. However, the total amount of bile acids in gizzard increased with access to wood shavings due to an increase in the weight of gizzard contents, indicating an increased gastroduodenal reflux. 6. Fibre concentration was considerably higher in the gizzard contents than in the feed. 7. Duodenal particle size decreased with access to grit. No effect of hulls or whole wheat inclusion was found, indicating that all particles are ground to a certain critical size before leaving the gizzard.     

Effect of soaking,germination, and enzyme treatment of whole barley on nutritional value and digestive tract parameters of broiler chickens

1. An experiment was carried out to determine the effect of soaking at 0°C, soaking at room temperature, germination, or enzyme treatment of whole barley on feeding value and digestive tract parameters of 2‐ to 4‐week old broiler chickens given diets with 700g/kg whole barley.

2. Soaking or germination decreased the soluble and total β‐glucan content (P<0.05) and, except for soaking at 0°C, the acid extract viscosity of the grain also decreased (P< 0.05). Germination and soaking in the presence of enzymes produced the lowest β‐glucan content and viscosity.

3. Except for soaking in cold water, the soaking, germination and enzyme treatments increased weight gain and decreased food: gain ratio (P< 0.05). Correspondingly, the digestibility of protein, fat, and ash, and the digestible energy content, increased (P< 0.05) after enzyme treatment or germination.

4. Chickens fed on enzyme‐treated or germinated barley diets had intestinal contents with a greater proportion of dry matter and lower viscosity than chickens fed on untreated barley (P< 0.05). Consequently, the cages and chickens were cleaner (P< 0.05) and the weight of digestive organs as proportion of live weight was lower.

5. Particle size analysis of excreta revealed that whole barley was efficiently ground by the gizzards of 16‐d‐old chickens, and very few whole kernels were found.     

Methionine+cystine requirement of broiler chickens fed low-density diets under tropical conditions

Two experiments were conducted to determine the M+C requirement of straight-run broiler chickens (Hubbard x Hubbard) during the period 4–21 (Exp. 1) and 21–40 (Exp. 2) days of age. Experiments were conducted during summer months (July–August) in open-sided houses, thus exposing chicks to chronic heat stress. Daily min-max temperature averaged 26–37C (Exp. 1) and 23–36C (Exp. 2). M+C deficient basal diets were formulated to contain low-nutrient-density, i.e., 2750 kcal per kg ME, 20.1% CP (Exp. 1), and 2780 kcal per kg ME, 17.0% CP (Exp. 2). Diets were supplemented with DL-methionine to provide total M+C level ranging from 0.64 to 0.89 % (six increments) and 0.54 to 0.79% (six increments), respectively in experiment 1 and 2. Requirements (0.95 of the maximum quadratic response) were found to be 0.77 and 0.75% total M+C, respectively for gain and feed efficiency, during 4–21 days; and 0.67% total M+C for both gain and feed efficiency during 21–40 days of age. Calculated on the digestible M+C basis, the estimates were 0.67 and 0.65% respectively for gain and feed efficiency during 4–21 days of age; and 0.60% for gain and feed efficiency during 21–40 days of age. Primary audience: Nutritionists, Formulators, Growers, and Poultry Researchers.     

Body composition and heat expenditure in broiler chickens fed diets with or without trans fatty acids

The effect of a diet containing trans fatty acids (TFA) on the fatty acid composition and fat accumulation was investigated in broiler chickens. Female broilers were fed a control or a TFA-containing diet. The difference between the diets was that a part of cis 18:1 in the control diet was replaced by the TFA. Body composition, energy balance and the fatty acid composition were examined. Over the time-period studied (15 days), the body fat content and the protein content did not differ significantly between the TFA-fed group and the control. In energy balance studies, total energy intake, energy loss in excreta, energy expenditure and energy storage did not differ between the treatments. Compared to the control diet, the TFA diet resulted in significantly higher amounts of 14:0 and 18:1n-7 and lower amounts of 18:1n-9 and 20:4n-6 in the body. In conclusion, the data suggest that feeding TFA for 15 days to female broilers had no effect on energy retention, energy expenditure and energy loss in excreta or in body composition in terms of fat and protein. Only the fatty acid composition in the body was affected by the treatment with TFA. In addition, 50% of ingested TFA was incorporated into the body fat. This may have a negative effect on the dietetic value of chicken meat.     

Water intake and water concentration in the body and gastrointestinal tract of intermittently fed broiler chickens

The relationship between water intake and water concentration in the body and in the gastrointestinal contents was studied in meat-type chickens fed either intermittently or ad libitum, as controls. In experiment 1, male broilers were reared from 12 to 33 d of age and were fed every second day or ad libitum. The water consumption of the intermittently-fed birds on days of food removal was 31% of the consumption of the control group. On days of food restoration their water consumption exceeded that of the controls, by 27%. No significant differences in water:food ratios were found between birds fed intermittently or the controls on days of food restoration. The restricted birds had a lower fat and a higher protein concentration in the body. No relationship was found between water:food ratio and body composition. In experiment 2, birds were kept on the same feeding regimes from 12 to 46 d of age. The water content of the pancreas increased after food restoration compared with ad libitum feeding or food deprivation. The amount of water in the gastrointestinal contents increased progressively from crop to ileum. The feeding regimens had no effect on the water content of the intestine.     

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.     

Rearing conditions influence nutrient availability of plant extracts supplemented diets when fed to broiler chickens

The effects of a standardised mixture of essential oils, including 5% carvacrol, 3% cinnamaldehyde and 2% capsicum (XT 6930; Pancosma S.A), on dietary apparent metabolisable energy corrected for nitrogen retention (AMEn), nutrient digestibility and mucin secretions, measured as sialic acid (SA) were investigated in broilers fed on the same diet but reared under different conditions, that is, cages and floor pens littered with wood shavings used in previous broiler study. The use of XT reduced (p < 0.05) nitrogen digestibility (0.585 vs. 0.544) and tended (p = 0.072) to reduce dry matter digestibility (0.733 vs. 0.717) of the diet when fed to birds reared in cages. However, XT supplementation improved (p < 0.05) fat digestibility (0.844 vs. 0.862) and tended (p = 0.093) to increase AMEn (14.01 vs. 14.25 MJ/kg DM) of the same diet when fed to broilers reared in floor pens. Essential oils supplementation tended (p = 0.059) to increase the secretion of SA, when fed to birds reared in cages (11.24 vs. 14.18 μg), but did not influence (p > 0.05) the SA secretion from birds reared in floor pens. The results obtained from the cage study tend to be the opposite of those obtained from the floor pen study. This suggests that the efficiency of dietary plant extracts may be influenced by the rearing/hygienic conditions of poultry. Based on the overall results, it can be concluded that information on rearing conditions should be taken into account for more complete interpretation of the experimental data emanating from experiments involving use of essential oils typified by those considered in this study.