EFFECT OF DIFFERENT CEREAL GRAINS ON MICROBIOLOGICAL STATUS OF HINDGUT CONTENTS IN THREE POULTRY SPECIES

Andrzej Wiliczkiewicz
Department of Animal Nutrition and Feed Quality, Wrocław University of Environmental and Life Sciences, Poland

ABSTRACT

The influence of the source of non-starch polysaccharides on microbial flora composition was examined (general number of aerobic bacteria, lactic acid bacteria, Escherichia coli, Enterobacteriaceae as well as yeast and mould) of hindgut of chickens, ducks and geese. When administering ground barley and rye in the concentrate mixtures for poultry, in place of maize their dietary fibre concentration was increased as well as the concentration of xylose and β-glucan. In the mixture whose main component was ground barley, a higher content of structural components was found, including hemicelluloses, in comparison to mixtures containing maize or rye.

Substituting ground maize with ground barley and rye in the mixtures for poultry, an increase of a general number of aerobic bacteria, lactic acid bacteria, Escherichia coli and Enterobacteriaceae was achieved in the content of ileum, colon and caecum. When feeding birds with ground barley, a decrease of yeast and mould amount was observed in the content of ileum and colon in comparison to a mixture with a high share of maize and rye grain. Independently of the diets applied, a larger general number of aerobic and lactic acid bacteria were observed in the content of the alimentary tract segments examined of ducks and geese in comparison to chickens. A smaller number of Escherichia coli, Enterobacteriaceae as well as yeast and mould were found in the intestinal content of ducks than in chickens and geese. SCFA correlation was negatively correlated, while pH reaction – positively, with structural carbohydrates share in the intestinal contents. A negative relation was found between the number of aerobic bacteria, lactic acid bacteria, Escherichia coli and Enterobacteriaceae and the concentration of hemicellulose in the birds’ intestinal content. The correlation between the number of bacteria in the intestinal content and SCFA [ ] concentration was positive, while it was negative in comparison to pH.

Key words: chickens, ducks, geese, cereal grain, alimentary tract, microbial flora.

INTRODUCTION

Non-starch polysaccharides (NSP) constitute a considerable part of cereal grains components, which form the basis of a poultry diet, and their content ranges from 97 gˇkg^-1 in the dry matter maize up to 232 gˇkg^-1 in oat grain [8]. Pentoses and hexoses, forming hemicelluloses, constitute a significant part of NSP [Non Starch Polysaccharides]. Hemicelluloses are not hydrolyzed by digestive enzymes of birds, but can be decomposed, to a much higher degree than cellulose, by enzymes produced by micro-organisms settling in the terminal segments of the alimentary tract [30]. Arabinoxylans constitute basic components of the hemicellulose fraction in the cereal grain. Arabinoxylans and β-glucans included in the cereal grains increase the intestinal content viscosity, limiting in this way the digestion and alimentary components absorption in poultry [25]. The solubility of arabinoxylans is determined by arabinose content. The higher the arabinose content in this fraction, the higher the solubility of arabinoxylans [4]. Barley grain includes the most of non-starch polysaccharides NSP among cereals (10.9 up to 18.3%) [8, 14], which is the result of the highest, and – to a large range – variable content of ß-D-glucans 3.0 – 8.8% [8, 14], including from 1.3 up to 4.0% in a soluble form [1, 27]. Among cereals, large amounts of arabinoxylans (>12%) are found in rye grain [4, 8]. According to Jeroch et al. [20], arabinoxylans can constitute even 7.3 up to 9.8% of rye with a significant share of a soluble fraction (2.2 up to 6.7%). Maize is the only grain used in the feeding of monogastric animals, including poultry, which can be used in doses without limitation. Dietary fibre in maize constitutes only approx. 10.7% [8, 27], and a low content of soluble non cellulosic polysaccharides (0.9%) is characteristic of this grain, in relation to their general content, amounting to 7.5% [8]. Unlike other cereals, maize includes small amounts of arabinoxylans (2.8%) and ß-glucans (<0.1%) [3]. Cereals also differ with regard to the structural carbohydrate content, including cellulose, which - together with hemicelluloses - constitutes the main component of cellular walls. The component share of the dietary dose and the alimentary component content in it effect the intestinal microbial flora [16, 32]. While investigating the intestinal flora of healthy turkeys, Bedbury and Duke [12] also found some amounts of yeast in the intestinal content but did not find any protozoan presence. The population of bacteria in the alimentary tract of adult birds is considerably diversified [21]. Approximately 40 identified types of anaerobic bacteria, represented by three or a higher number of species, were found in the alimentary tract of poultry [9]. In general, over 400 various bacteria species were determined [Apajalahti, unpublished data; after 13]. Their highest number occurs in caecum, about 12 log cfu·g^-1 [11]. The goal of this study has been to determine the effect of applying maize, barley and rye grain in concentrate mixtures, as a basic source of non starch polysaccharides, for feeding chickens, ducks and geese on the microbial flora composition in ileum, colon and caecum content. The study has also aimed at determining the correlation between structural carbohydrate concentration, pH, SCFA [Short Chain Fatty Acids] and the number of micro-organisms in the content of the birds’ intestine segments examined.

METHODOLOGY

Two experiments were conducted with Hybro-N cockerels, ganders of White Italian breed and WD-1 stock, and Astra drakes (K-2 stock). In both experiments the birds were kept in a floor system, and in the 20^th day of life they were sampled within each species into three experimental groups, each in three repetitions of 4 animals every time (total of 108 animals in 27 repetitions). Three mixtures were prepared for the birds including on average of 11.8 MJ×kg^-1 of metabolic energy and approx. 19% of crude protein (table 1). The fodders differed with regard to the cereal grain constituting a basic source of carbohydrates. The fodder for group I included 64% of maize, for group II – 63% of barley and for group III – 30% of rye and 33% of wheat. The concentrate mixtures administered to the birds in both experiments were prepared one time, and their components came from the same batches of fodder.

The birds were slaughtered before they finished the sixth and eighth week of life. Directly after slaughter, tissue samples were collected from the terminal part (about 25 cm) of ileum, colon and caecum in such a manner that they included no more than 1 g of contents. The samples in sterile packaging were sent to microbiological assays. The remaining intestine parts were emptied out of contents. pH of the obtained content was determined, and then samples were taken in order to determine SCFA and dry matter. Dry matter, crude fibre, NDF (Neutral Detergent Fibre) and ADF (Acid Detergent Fibre) were determined in the pre-dried samples of intestinal content.

The alimentary component content (dry matter, crude protein, crude fibre) in the fodder and intestinal content was determined by means of standard methods staying in accordance with AOAC [5]. Fibretec apparatus manufactured by Tecator was used for the crude fibre determination. ADF, NDF and ADL (Acid Detergent Lignin) assays were performed with Van Soest method [34]. Hemicellulose content was calculated as a difference between NDF and ADF, while cellulose content – by subtracting the ADL amount from the ADF amount. Total dietary fibre (TDF) with a division into insoluble fraction (IDF) and soluble one (SDF) was determined by means of Asp et al. method [7].

The pH determination of the intestinal content was conducted with the potentiometrical method (pH-meter Medical Mat 1202 SM). While determining the concentration of short chain fatty acids (SCFA), the weighed samples of the intestinal content (2 g) were inundated with concentrated phosphoric acid (0.5 ml), formic acid (0.5 ml) and 2 ml of deionized water in order to dilute the sample. After thorough mixing and centrifugation, the fatty acids were separated using gas chromatograph PYE UNICAM-104 with 27 cm column.

The samples for the determination of micro-organisms were prepared by weighing 1 g of the intestinal content into 9 ml of buffered peptone water, and were homogenized. Subsequent decimal dilutions of these samples were cultured onto solid bacteriological media. The general number of bacteria was determined using NPL method of TSB medium (incubation temperature 37°C, reading after 72 hours). Lactic acid bacteria were assayed on MRS medium, at the temperature of 30°C, and the result was read after 72 hours. Escherichia coli were determined with the use of cultures from subsequent decimal dilutions onto Chromocult Coliform Agar medium manufactured by Merck (incubation temperature 37°C, reading after 72 hours). Enterobacteriaceae were determined on agar medium VRBG manufactured by Oxoid (incubation temperature 37°C, reading after 72 hours). Yeast and moulds were determined using yeast-peptone-glucose agar with the addition of chloramphenicol (Chloramphenicol Yeast Glucose Agar) (incubation temperature 25°C, reading after 7 days).

The test results were analyzed with statistic methods by means of two-way variance analysis according to the following model:

y_ijk = μ + α_i + β_j + (αβ)_ij + ε_ijk

Particular elements in the formula of the model have the following meaning:

- y_ijk – value of the dependent variable observed,
– μ – general mean,
– α_i – diet effect,
– β_j – bird species effect,
– (αβ)_ij – interaction between diet type and bird species,
– ε_ijk – residue error.

The numerical material concerning the microbial flora and the alimentary tract content was transformed with a logarithmic method (log₁₀) before conducting further statistical analyses. The significance of differences between the mean values was determined by means of Duncan test. The significance of Pearson correlation coefficients was determined with t test. The calculations were made with the use of Statistica 6.0 software [31]. Graphs were elaborated using Excel spreadsheet (Microsoft^® 2000). The mean values of the test results, calculated for groups of the experiment factors investigated were presented in a tabular form, while intermediate values (within both factors) were presented in the form of graphs.

RESULTS

Experimental mixtures administered to the birds included similar amounts of crude fibre, on average 4.6%, while differing significantly with regard to the fibre fraction level determined with Van Soest method (table 2). The diets including barley as a basic source of structural carbohydrates contained 16.9 % NDF, 6.6 % ADF, 10.3 % hemicelluloses and 5.7 cellulose, and when maize or rye was introduced the share of these fractions was lower (on average 13.6 % NDF, 5.3 % ADF, 8.3 % hemicelluloses and 4.4 % cellulose). The dietary fibre concentration was also diversified; mixtures for birds of group I included 13.8% of this component, while in the group with barley 19.8% (III), and with rye 17% (III). A high content of soluble dietary fibre fraction (3.7 % and 2.3 %) was characteristic of mixtures including barley and rye as their main component, while the diet including maize had only 0.7% of this fibre fraction. The introduction of ground barley to the mixture for group II resulted in the increase of structural carbohydrate fraction content and lignin content by about 16% (crude fibre) up to 25% ADF, and dietary fibre by about 43% in comparison to the remaining groups. A significant increase of xylan content from 2.2% in the mixture for group I up to 3.5% on average in groups II and III is also worth mentioning. Β-glucan content in the mixture for group I amounted to 0.1%, while for groups II and III – 2.3% and 0.7% respectively.

Experiment 1

The average body weight of 20-day old birds introduced into the experiment amounted to 0.87 kg on average. In the sixth week of life, the weights of cockerels, drakes and ganders were 1.08, 1.55 and 2.52 kg respectively, while in the eighth week – 2.25, 2.61 and 4.39 kg. The daily fodder intake by poultry in the diet groups was on average 204 in the sixth week, and 237 g/animal in the eighth week. During the first period these parameters ranged to 139 for chickens, 212 for ducks and 259 g/animal for geese, while in the second period it was 146, 236 and 331 g/animal respectively.

The average number of aerobic bacteria (table 3) in the content of ileum found in the group of birds receiving in the diet 30% of ground rye (III) amounted to 8.76 log cfu×g^-1, and was higher (p≤0.05) in comparison to group II fed with concentrate mixture including ground barley (8.21 log cfu×g^-1). The total number of these bacteria in the colon content was not very diverse, and oscillated between 8.16 up to 8.38 log cfu×g^-1. The highest average number of bacteria in the colon content amounted to 8.92 log cfu×g^-1 (group III), while the lowest was 8.36 log cfu×g^-1 (group I). The general number of aerobic bacteria in the content of particular alimentary tract segments of the birds was the lowest in chickens, and in ileum it amounted to 7.27, while in the colon and caecum it was 7.24 and 7.93 log cfu×g^-1. The means for ducklings and goslings were 9.04 log cfu×g^-1 (p≤0.01) in ileum, 8.76 log cfu×g^-1 (p≤0.01) in colon and 8.74 and 9.27 log cfu×g^-1 (p≤0.05) in caecum.

More (p≤0.05) lactic acid bacteria were found in caecum content of geese 8.93 log cfu×g^-1 in comparison to the mean value in chickens amounting to 7.72 log cfu×g^-1. In dietary groups the average number of these bacteria ranged from 7.63 up to 8.10 log cfu×g^-1 in ileum content, 7.49 up to 7.93 log cfu×g^-1 in colon content, and 8.22 up to 8.42 log cfu×g^-1 in caecum, where these values were closest to each other. The average number of lactic acid bacteria in ileum content of chickens, ducklings and goslings was very diversified and amounted to 6.80, 8.11 and 8.84 log cfu×g^-1 respectively, however the differences between these values were not proved to be statistically significant. A lower (p≤0,05) mean value was observed in colon in cockerels – 6.80 log cfu×g^-1 – in comparison to ducklings and goslings (on average 8.27 log cfu×g^-1).

No statistically significant differences between means were found with regard to Escherichia coli number calculated for dietary groups of birds, in spite of distinctly higher values determined in ileum and colon content in group III (4.71 and 4.78 log cfu×g^-1) in comparison to the control group (3.69 and 4.12 log cfu×g^-1). The lowest number of these bacteria determined in ducks was on average: in ileum 3.29, colon 3.54 and caecum 4.58 log cfu×g^-1. More (p≤0.05) Escherichia coli bacteria in comparison to ducks were determined in chickens in ileum (4.75 log cfu×g^-1), while in colon of chickens and geese the mean number of these bacteria was about 6.21 log cfu×g^-1.

The number of yeast and mould in the ileum content ranged from 2.52 log cfu×g^-1 (I) up to 3.28 log cfu×g^-1 (III), in colon from 2.38 up to 3.53 log cfu×g^-1 (p≤0.05) and in caecum from 2.75 up to 3.18 log cfu×g^-1. The general number of fungi was on average lowest in ducks and amounted to 2.62 in ileum content, 2.60 in colon and 2.35 log cfu×g^-1 in caecum.

Correlation coefficients (table 4) were calculated on the basis of data concerning the basic parameters of the intestinal content. The structural carbohydrate content was negatively interdependent with SCFA concentration, while the correlation coefficients values ranged from r = -360 for ADF up to r = -0.644 in case of hemicelluloses. SCFA level was positively correlated with pH reaction of the intestinal content (r = 0.394 up to 0.528). The correlation coefficients turned out significant also between the concentration of all the structural components investigated and the number of lactic acid bacteria, and in case of hemicelluloses – with the number of aerobic bacteria and Escherichia coli. The number of examined bacteria was positively correlated with SCFA concentration, and negatively correlated with pH reaction. Moreover, the correlation coefficient between the number of lactic acid bacteria and Escherichia coli bacteria turned out significant.

Experiment 2

Weights of three-week old birds at the beginning of the experiment were on average 0.94 kg in dietary groups, and in the eighth week of life 3.42 (I), 3.39 (II) and 3.20 kg (III). Mean weights of three-week old cockerels, drakes and goslings were 0.62, 1.02 and 1.18 kg, while in the sixth week they amounted to 1.10, 1.39 and 2.53, and in the eighth week 2.37, 3.01 and 4.62 kg. Six-week old birds consumed on average 204 g/day/animal of concentrate mixtures, while in the eighth week it was 237 g/day/animal. Fodder consumption during the first analyzed period in chickens, ducks and geese amounted to 139, 212 and 259 g/day/animal respectively, and during the second period it was 136, 236 and 331 g/day/animal.

The lowest general number of aerobic bacteria in the ileum content was observed in birds fed with the mixture including ground barley (group II) 6.82 log cfu×g^-1, while the highest number - in group III, where the dominant mixture component was ground rye 7.69 log cfu×g^-1 (table 5). The general number of bacteria in colon increased proportionally to 7.78 in group II, and 8.65 log cfu×g^-1 in group III. The number of these bacteria in the content of the caecum was on average 8.94 log cfu×g^-1. The lowest number of aerobic bacteria was determined in the contents of colon and caecum in chickens – 7.61 and 8.51 log cfu×g^-1 respectively in control groups. In this experiment, the general number of bacteria in ileum was distinctly lower in chickens (6.41 log cfu×g^-1) in comparison to ducks (7.74 log cfu×g^-1) (p≤0.05) and geese (7.47 log cfu×g^-1). Similar relations between the number of aerobic bacteria in the examined birds were observed in colon content; in cockerels this number was 7.28 log cfu×g^-1, in drakes 8.48 log cfu×g^-1 and in goslings 8.28 log cfu×g^-1. The general number of bacteria in the content of caecum was equal among the poultry species, and assumed values in the range from 8.68 log cfu×g^-1 in chickens up to 8.92 log cfu×g^-1 in ducklings.

A relatively equal number of lactic acid bacteria was obtained in the content of particular intestine segments through feeding the birds with concentrate mixtures of varied NSP level. The determined number of lactic acid bacteria in ileum assumed values from 6.60 in group II up to 7.14 log cfu×g^-1 in group I, in the colon content from 6.41 in group I to 6.56 log cfu×g^-1 in group II, while in caecum – from 6.74 log cfu×g^-1 in group I up to 7.67 log cfu×g^-1 in group III. The number of lactic acid bacteria in the content of the analyzed alimentary tract segments of the birds differed slightly among the bird species. The lowest values in all the discussed intestine segments were observed in chickens and the highest in goslings, and they amounted to – respectively for the mentioned species, in ileum content 6.70 and 7.15 log cfu×g^-1, in colon 6.32 and 6.78 log cfu×g^-1, and in caecum 6.84 and 7.49 log cfu×g^-1.

In the ileum content of birds of group (I), taking ground maize as the main component of concentrate mixture, a lower (p≤0.05) number (5.12 log cfu×g^-1) of Enterobacteriaceae was found in comparison to the group taking ground barley as the basic source of carbohydrates (II) 5.80 log cfu×g^-1. The number of Enterobacteriaceae in the content of caecum was similar in the compared poultry groups and ranged from 5.95 (I) up to 6.88 log cfu×g^-1 (II). The lowest number of Enterobacteriaceae was observed in drakes, and the highest in goslings – in ileum, 5.20 and 5.60 log cfu×g^-1 respectively, in colon 5.33 and 6.57 log cfu×g^-1 and in caecum 6.03 and 6.75 log cfu×g^-1.

Regardless of the poultry species and dietary group, no yeasts or moulds or their small amount were found in the analyzed intestine content samples.

The correlation coefficients between the examined parameters of the poultry intestinal content, calculated according to the same rules as in experiment one, were very low in most cases (table 6), yet the direction of interdependence was maintained. Only the values of correlation coefficients between SCFA and crude fibre content and ADF (p≤0.05) as well as NDF and hemicelluloses (p≤0.01.) were proven statistically significant. Also, the interdependence between the number of Enterobacteriaceae type bacteria and hemicellulose concentration in the content of intestines (r = -0.371) and SCFA concentration in them (r = 0.383) proved to be statistically significant.

DISCUSSION

Charts presenting the number of aerobic bacteria and lactic acid bacteria in the content of the examined intestine segments show mean values from both of the conducted experiments (Fig. 1-6). However, in case of yeast and mould, for which divergent results were obtained in the second experiment, only the values coming from the first experiment were presented (Fig. 13, 14 and 15). The number of Escherichia coli bacteria from the first experiment was presented in charts 7, 8 and 9, while Enterobacteriaceae from the second experiment – in graphs 10, 11 and 12.

Only few results of comparative studies were found in available literature concerning the application of various sources of non starch polysaccharides in several poultry species simultaneously. Choct [unpublished data, after 6] observed the increase of Enterococcus bacteria number (p≤0.05) in the content of caecum, when feeding chickens with maize in their diet; the presence of barley favored the occurrence of Lactobacillus; while rye – Streptococcus.

The general number of aerobic bacteria determined in the content of ileum in both experiments oscillated from 6.41 up to 9.05 log cfu×g^-1, in colon from 7.24 up to 8.82, and in caecum these values were least diversified, and ranged from 7.93 up to 9.27 log cfu×g^-1. The general number of this type of bacteria in the content of ileum – according to various authors – has the values of: from 5.5 up to 7.3 log cfu×g^-1 [6, 28, 34], in colon content from 6.7 up to 8.9 log cfu×g^-1 [2, 15, 33]. The highest number of aerobic bacteria is present in caecum, and the values determined in chickens in this intestine are included in the range from 7.7 up to 11.8 log cfu×g^-1 [2, 10, 17, 28]. The authors of this study found a comparable or higher number of bacteria in ileum and caecum content in all groups of birds taking mixtures different than those including ground maize as their basic component. Also Wagner and Thomas [35], when feeding chickens with mixtures of high content of ground rye, found significant increase of the bacteria quantity in ileum in comparison to chickens fed with fodder including mainly ground maize. In the intestinal content of waterbirds, regardless of the diet applied, a higher number of these bacteria were usually found in comparison to chickens (fig. 1, 2 and 3). Wiliczkiewicz et al. [37] found in geese only slightly lower quantities of aerobic bacteria both in ileum and colon content than in chickens, while in ducks, similarly to this study, significantly higher quantities of these bacteria were found in the content of ileum and caecum in comparison to chickens [36].

The number of lactic acid bacteria determined in the content of the analyzed intestine segments, in both presented experiments, was very similar to the general number of bacteria within the investigated bird species as well as in particular dietary groups of the experiment (Fig. 1-6). The number of these bacteria in the examined poultry in ileum content oscillated from 6.70 up to 8.84 log cfu×g^-1, in colon 6.32 up to 8.32 log cfu×g^-1, and in caecum from 6.72 up to 8.93 log cfu×g^-1. Jamroz et al. [18], when substituting ground maize with wheat and barley in the mixtures for three-week old chickens, found a higher number of lactic acid bacteria (p≤0.05) in caecum content, while in seven-week old chickens the number of these bacteria was identical. In other studies, these authors [19], when introducing ground barley instead of ground maize in the diets for seven-week old chickens, found a higher (p≤0.05) number of lactic acid bacteria in their ileum and caecum content, which confirms the results presented in this study. A similar tendency in the content of ileum and caecum was observed by other authors when substituting maize in mixtures for birds with wheat and barley [16, 18, 19, 24]. Hűbener et al. [16] found a higher number of lactic acid bacteria in 42-day old chickens in ileum and caecum content when using – in the feeding of these birds – mixtures including wheat and rye as the basic NSP source in comparison to maize. A higher number of lactic acid bacteria were determined in the intestinal content of waterbirds in both presented experiments, while in ducks and geese receiving ground barley or rye in their diet similar quantities of these bacteria were found, and they were higher than in groups receiving maize in all intestine segments examined (Fig. 4, 5 and 6). In the intestinal content of chickens taking mixtures with barley, a significantly lower number of lactic acid bacteria were found. In previous studies, a lower number of these bacteria were found in chickens in comparison to ducks [36]. However, Wiliczkiewicz et al. [37] did not observe any significant differences in the number of lactic acid bacteria in the intestinal content between these species of birds when conducting experiments on adult ganders and cocks.

The number of Escherichia coli bacteria determined in ileum and colon of the birds was higher when ground barley and rye dominated in the mixtures in comparison to the diet including maize. Lower quantities of these bacteria were found as a rule in ducks in comparison to chickens and geese (Fig. 7, 8 and 9). While comparing the maize diet to the one including wheat and barley, Mathlouthi et al. [24] found a lower number (p≤0.01) of Escherichia coli bacteria in the caecum content of chickens. Jamroz et al. [18], on the other hand, when substituting ground maize with wheat and barley in the mixtures for chickens found a higher number of Escherichia coli bacteria (p≤0.05) in 21-day old chickens. Apajalahti et al. [6] found that the introduction of rye to the mixtures in place of maize significantly increases the number of Escherichia coli bacteria in small intestine of chickens.

Hűbener et al. [16] noted a smaller quantity of Enterobacteriaceae bacteria in the content of ileum and caecum of six-week old chickens receiving mixtures including wheat and rye as a basic source of structural carbohydrates in comparison to the birds fed with fodder including maize. A similar tendency was observed in this study. The using of barley and wheat grain in the mixtures caused the increase in the quantity of these bacteria in the contents of all examined intestine segments of poultry in comparison to the group of birds taking maize. A smaller quantity of Enterobacteriaceae was observed in the contents of all intestine segments in ducks in comparison to chickens and geese. A higher number of these bacteria in the content of ileum and caecum in ducks taking barley in their diet was an exception (Fig. 10, 11 and 12). These data are confirmed by studies conducted by Wiliczkiewicz et al. [37].

The number of yeast and mould determined in the content of particular intestine segments of the birds was characterized by very high variability. These micro-organisms were found in the content of the birds’ ileum and colon in the quantity from 0.0 up to 3.53 log cfu×g^-1, while in the caecum from 0.0 up to 3.64 log cfu×g^-1. The lowest quantity of fungi was observed in the intestinal content of ducks, up to 2.62 log cfu×g^-1, while the highest – in chickens and geese, up to 4.4 log cfu×g^-1. The relations between the species of birds with regard to yeast and mould number in the intestinal content were also maintained within the dietary groups (Fig. 13, 14 and 15). Jamroz et al. [18] determined higher (p≤0.01) quantities of fungi in the content of chickens’ caecum by feeding them with a mixture with a high share of wheat and barley in comparison to a standard mixture including ground maize. While comparing similar mixtures [19] in 41-day old chickens, they a found similar quantity of fungi in their ileum.

The chemical composition and structure of the alimentary tract content determine the proportions between particular bacteria species [26, 29, 35]. The presence of SCFA is one of the results of the microbiological activity in the intestinal content, while the composition of bacterial flora determines the amount and type of produced SCFA [22]. Similarly to the previous study, in which the experiments were conducted on chickens and ducks [36], also this study has proved negative relationships between the concentration of structural carbohydrate fraction and the concentration of SCFA in the intestinal content of the birds. Besides, a significant positive interdependence between these fractions and pH reaction was confirmed in the first experiment. Marounek et al. [23] proved in their research that the amount of SCFA produced in caecum is substantially dependent on the type of non starch polysaccharides constituting the medium of bacterial development. In both experiments, the correlation coefficients between the number of bacteria in the intestinal content and SCFA concentration assumed positive values, while negative ones in comparison to pH. Other studies [36, 37] confirmed the direction of the interdependencies mentioned, obtaining much higher correlation coefficient values than in this study.

CONCLUSIONS

The introduction of ground barley and rye to the concentrate mixtures in place of maize resulted in the increase of the dietary fibre concentration as well as xylose and β-glucans. A higher content of structural components, including hemicelluloses, was found when barley grain constituted the diet basis in comparison with mixtures including maize or rye.

The increase of non starch polysaccharides in the mixtures for poultry increased the general number of aerobic bacteria, lactic acid bacteria, Escherichia coli as well as Enterobacteriaceae bacteria in the content of lower segments of the alimentary tract.

Smaller quantities of yeast and moulds were observed in the content of ileum and colon while feeding birds with ground barley.

A higher total number of aerobic bacteria and lactic acid bacteria was found in the content of ileum, colon and caecum of ducks and geese in comparison with chickens independently of the diets applied. Independently of the diet, a smaller quantity of Escherichia coli and Enterobacteriaceae bacteria as well as yeast and mould were found in the intestinal content of ducks in comparison to chickens and geese.

The structural carbohydrate content in the intestines was negatively correlated with SCFA concentration and positively - with pH reaction. A negative dependence was found between the number of aerobic bacteria, lactic acid bacteria, Escherichia coli, Enterobacteriaceae and hemicellulose concentration in the intestinal content of the birds. The interdependence between the number of bacteria in the intestinal content and SCFA concentration was positive, while negative in comparison to pH.

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