Arch.Geflügelk., 75 ( 2). S. 132- 139 , 2011, ISSN 0003-9098. © Verlag Eugen Ulmer, Stuttgart

Performance, foot-pad dermatitis and haemoglobin saturation in broiler chickens kept on different types of litter

Leistung, Häufigkeit an Pododermatitis und Hämoglobinsättigung bei Broilern bei Haltung auf verschiedenen Einstreusubstraten

1 Department of Poultry Science, Poznań University of Life Sciences, Poland 2 ‟Mark-Drob” Poultry Firm, Chludowo, Poland

Manuskript eingegangen am 16. April 2010, angenommen am 12. Juni 2010

Summary The aim of the study was to determine the effect of different types of litter on broiler chickens production results and health. Two flocks and six replications of every litter were carried out. The experimental material was Ross 308 broiler chickens (4,320 birds) kept from 0 to 42 days of life on three types of litter: wheat straw, chopped wheat straw and wood shavings (720 birds on each litter type). The following parameters were recorded: body weight on a weekly basis and feed intake and foot-pad dermatitis – FPD on days 7, 14, 21, 28, 35 and 42 of rearing (body weight and FPD were controlled in 90 chickens kept on each type of litter). The following indices were calculated: mean body weight gains (g/bird/day), FCR (kg/kg b.w.) and EPEF (points). On day 41 of birds’ life, haemoglobin saturation (%) was assessed in 54 birds, 9 cockerels and 9 hens from each type of litter. Besides on day 42, carcass yield (%) was assessed in 30 birds from each type of litter. The highest body weight (42 day) was determined in broilers kept on wood shavings ( = 2,482 g). Tendency for better feed intake, daily body weight gains and lower mortality was observed in the treatment when broilers were kept on wood shavings. Also FCR (1.62 kg/kg b.w.) was found the lowest on this litter. The EPEF value for these chickens was by 50 points higher than on the remaining litters. In comparison with the remaining litters, broilers kept on wood shavings showed by about 0.90 point lower mean foot-pad dermatitis. Birds of both sexes kept on chopped wheat straw and wood shavings exhibited similar haemoglobin saturation ( = 85.3%). The lowest haemoglobin saturation was observed in birds kept on wheat straw ( = 74.3%). Broiler chickens kept on wood shavings were characterized by the highest body weight, lowest FCR and the smallest foot-pad dermatitis during the entire period of rearing.

Key words Broiler chicken, litter type, performance, foot-pad dermatitis

Zusammenfassung Leistung, Häufigkeit an Pododermatitis und Hämoglobinsättigung bei Broilern bei Haltung auf verschiedenen Einstreusubstraten Im Rahmen der Studie sollte der Einfluss von verschiedenen Einstreusubstraten auf die Leistung und die Gesundheit von Broilern untersucht werden. Jedes Einstreu­substrat wurde an zwei Herden mit sechs Wiederholungen geprüft. Für die Untersuchung wurden Broiler der Herkunft Ross 308 (N = 4320 Broiler) verwendet, die zwischen dem 0. und dem 42. Lebenstag auf Weizenstroh, gehäckseltem Weizenstroh oder Hobelspänen (jeweils 720 Tiere) gehalten wurden. Folgende Merkmale wurden erfasst: Lebendgewicht und Futteraufnahme wöchentlich, Bewertung des Auftretens und der Schwere von Pododermatitis (FDP) am 7., 14., 21., 28., 35. und 42. Lebenstag. Die Lebendgewichte und FDP wurden für jedes Einstreusubstrat an 90 Tieren ermittelt. Aus den Daten wurden die durchschnittlichen täglichen Zunahmen (g/Tier/d), die Futterverwertung (kg/kg Lebendmasse) und der Europäische Produktionsfaktor (EPEF; Punkte) berechnet. Am 41. Lebenstag wurden bei 54 Broilern (9 männliche und 9 weibliche je Einstreusubstrat) die Hämoglobinsättigung (%) bestimmt. Ferner wurde am 42. Lebenstag die Schlacht­ausbeute von 30 Broilern je Einstreusubstrat ermittelt. Bei Haltung der Broiler auf Hobelspänen wurden am 42. Lebenstag die höchsten Lebendmassen erreicht ( = 2482 g). Ferner wurden tendenziell bei diesem Einstreusubstrat eine bessere Futteraufnahme, höhere tägliche Zunahmen und eine geringere Mortalität beobachtet. Generell waren die Futterverwertung bei dieser Behandlung am günstigsten (1,62 kg/kg) und der EPEF-Index um 50 Punkte höher als bei den anderen Behandlungen. Im Vergleich zu den anderen Behandlungen wiesen Broiler, die auf Hobelspänen gehalten wurden, eine etwa um 0,9 Punkte günstigere Bewertung des Fußballenzustandes auf. Eine ähnliche Hämoglobinsättigung ( = 85,3%) wurde unabhängig vom Geschlecht bei Broilern festgestellt, die auf gehäckseltem Weizenstroh oder auf Hobelspänen gehalten wurden. Die geringste Hämoglobinsättigung wurde bei den Tieren von der Weizenstrohbehandlung ermittelt ( = 74,3%). Zusammenfassend kann festgestellt werden, dass bei einer Haltung der Broiler auf Hobelspänen die höchsten Gewichtszunahmen und die günstigste Futterverwertung in der Mastperiode erzielt werden kann, bei gleichzeitig den geringsten Veränderungen an den Fuß­ballen.

Stichworte Broiler, Einstreumaterial, Leistung, Pododermatitis

Introduction

Intensive selection of broiler breeders in the direction of rapid growth rate and increased final body weight has led to the appearance of a number of metabolic diseases in broilers. The most important among them include sudden death syndrome (SDS) and ascites which are directly associated with cardiovascular and respiratory system failure of rapidly growing birds (Kranen et al., 1998; Imaeda, 2000; Wideman, 2001). Ascites is connected very frequently with the phenomenon of hypoxemia caused by reduced oxygen content in blood (Buys et al., 1999). Both, lower blood oxygen pressure (pO 2 ) and smaller haemoglobin saturation (Peacock, 1990; Olkowski et al., 1999) were observed in fast-growing broiler chickens.

Thus, it must be underlined that cardiovascular and respiratory system efficiency cooperation, whose dysfunction influences significantly the incidence of ascites, can depend not only on bird’s rate of growth but also on environmental conditions in which they live, including litter quality. It was shown, that dust in the airspace of broiler chickens may increase the incidence of ascites. It can effectively reduce the efficiency of oxygen uptake inside the lungs (Zuidhof et al., 1997). There were also experiments which tried to analyze the frequency of ascites occurring in broilers when litter with canola oil was used to decrease its dust (McGovern et al., 1999). It was also affirmed that the level of ammonia in the air affects ascites incidence (Terzich et al., 1998).

Among increasing problems in broiler chicken and turkey rearing there are contact skin inflammations which can occur either in the form of oedema in the area of breast, popliteal fossa or, most frequently, in the region of foot-pad (foot-pad dermatitis – FPD) (Ekstrand et al., 1998; Kjaer et al., 2006). Serious lesions of the pad can be very painful and cause stress and lead to the appearance of other infections causing deterioration of general health condition and reduced production results, including poorer body weight gains and lower final body weights (Martland, 1984 and 1985; Campo et al., 2005). Among major factors, the type and quality of litter seems to contribute to the above-mentioned problems. Already Martland (1984) and Greene et al. (1985) reported interrelationships between litter moisture content and frequency as well as prevalence of foot-pad dermatitis in broiler chickens. In addition, also Hester et al. (1997) found that the use of course particleboard residue as litter for turkey led to the increase of FPD incidence in comparison with birds which were kept on fine particleboard residue or wood shavings. Therefore, it seems that the relation between the type of litter and the FPD prevalence results in all probably from water content in examined litter. Thus, a higher water content in the litter impairs the wellbeing of the legs.

In view of the above, it seems important to carry out investigations involving, among others, the analysis of the suitability of rearing broiler chickens on different types of litter, the possibilities of improvement of its quality and the impact of the applied substrate on health and performance of broilers (Goetsch et al., 1998; Ivanov, 2001; Sogunle et al., 2006) taking into consideration primarily their welfare.

Bearing in mind a number of activities already in progress aiming at the improvement of effectiveness and profitability of broiler chickens rearing, the authors of this study adopted as the objective of their investigations the determination of the impact of different types of litter employed in broiler chicken rearing on their performance and health condition. In addition, they aimed to find the answer to the question which of the applied litters is the best.

Material and methods

The experiment was conducted on a private farm in western Poland. A single chicken house (area 400 m2) and 4,320 Ross 308 as hatched day old chickens were used in the study.

Animals and husbandry

Two flocks and six replications were carried out. The birds were kept in environmental conditions typical for broiler chickens. The initial temperature in the chicken house (day 0) was 35°C and was successively decreased by 1°C every 48 hours, so that by day 35 of rearing, it reached the level of 18°C. The heating system used gas blowers and the rela­tive air humidity in the house was maintained at 65–70%. Day old chicks were brought in on 0 h darkness. The dark period increased weekly from 1 hour at 4–7 days to 6 h at 28–35 days. One hour of light was then added daily so that on day 42 the birds were exposed to 24 h light.

The experimental birds were fed ad libitum complete diets: STARTER (from day 0 to day 12), GROWER I (from day 13 to day 21), GROWER II (from day 22 to day 35) and FINISHER (from day 36 to day 42) which contained, respectively, 12.3 and 22.0; 12.8 and 20.7; 13.1 and 19.7 as well as 13.2 MJ/kg ME and 18.7% crude protein. The birds had unlimited access to fresh, clean water from drop water fountains – nipple drinkers with cups.

Treatment and replications

In experiment three treatments (type of litter – wheat straw, chopped wheat straw and wood shavings) were applied. Straw was spread 7–10 cm thick and wood shavings – about 7 cm thick. There were 9 pens (pen area = 12 m2) in the chicken house. In each pen 240 birds (unsexed chickens) were kept from 0 to 42 days of life per each flock. The bird stocking rate was 20 birds/m2. Summarized, there were 6 replications per treatment in 2 flocks of birds through the house (3 replications per treatment per one flock).

Measures

In the course of rearing of each flock, broiler chickens (90 birds from each litter, 30 birds from each pen) were randomly selected and weighted on a weekly basis. On days 7, 14, 21, 28, 35 and 42 the amount of feed consumed was recorded and foot-pad dermatitis (90 birds from each litter, 30 birds from each pen) was assessed subjectively according to a 3-point scale (Ekstrand et al., 1997 and 1998) as follows: 0 point – lack of lesions, discoloration or scars, 1 point – mild lesions, only on superficial skin, some erosions, papillae and foot-pad discoloration, and 2 point – serious and deep lesions of the foot-pad, abscesses and scabs (Figure 1). The scores of both feet were used for statistical analysis. Dead birds were removed every day. The following traits were calculated for each pen: mean feed consumption and mean body weight gain (g/bird/day), feed conversion ratio (FCR – kg/kg b.w.) as well as the European Production Efficiency Factor (EPEF). The EPEF was calculated according to the formula: EPEF = mean body weight (kg) × liveability (%) × 100/days × FCR (kg). In addition, on day 42 of rearing in the second flock after slaughter carcass yield was estimated in 90 randomly selected birds (30 birds from each litter type, 10 birds from each pen).

Figure 1. Severity of foot-pad dermatitis according to the 3-point scale of Ekstrand et al. (1997 and 1998; 0 point – lack of lesions, discoloration or scars; 1 point – mild lesions, only on superficial skin, some erosions, papillae and foot-pad discoloration; 2 points – serious and deep lesions of the foot-pad, abscesses and scabs) Schweregrad der Pododermatitis nach der 3-Punkte-Skala von Ekstrand et al. (1997 and 1998; 0 Punkte – keine Läsionen, Verfärbungen oder Risse; 1 Punkt – milde Läsionen, nur auf der Hautoberfläche, einige Erosionen, Papillen und Verfärbungen; 2 Punkte – schwere und tiefe Läsionen auf dem Fußballen, Abszesse und Wundschorf)

Finally, 1 kg cross sectional samples of the litter from each pen was collected on day 42 for chemical analysis.

On day 42 haemoglobin saturation (%) was assessed using pulse-oximeter Vet/Ox® G2DigitalTM Monitor in 54 randomly selected chickens (9 males and 9 females from each litter, 3 males and 3 females from each pen). After catching the birds from pens, weighing and calming down, they were connected to the sensor monitoring blood saturation.

Statistical Analysis

Statistical calculations were conducted with the assistance of the SAS® v. 9.1 package. Mean values ( ) as well as the standard error of the mean (SEM) were calculated for all traits. Differences between individual kinds of litter with regard to body weight on day 42 of life, FCR and EPEF were determined employing the three-way linear model of ANOVA:

Y ijkl = µ + s i + l j + r k + e ijkl

where: y ijkl – phenotypic value of the trait for the lth group of chickens, of ith sex, on the jth litter, in the kth flock, µ – mean value of the trait for a given population, s i – effect of ith sex (i = 1,2) l j – effect of jth litter (j = 1,2,3), r k – effect of kth flock (k = 1,2), e ijkl – effect of experimental error.

Differences between the individual litter types with regard to body weight gain, feed intake and mortality were determined using the four-way linear model of ANOVA:

Y hijkl = µ + s h + w i + l j + r k + e hijkl

where: y hijkl – phenotypic value of the trait for the lth group of chickens, of hth sex, in the ith week, on the jth litter, in the kth flock, µ – mean value of the trait for a given population, s h – effect of hth sex (h = 1,2) w i – effect of ith week (i = 1, 2, 3, 4, 5, 6), l j – effect of jth litter (j = 1, 2, 3), r k – effect of kth flock (k = 1, 2), e hijkl – effect of experimental error.

A non-parametric statistical analysis was used for evaluation of FPD. In addition, the percentage incidence of foot-pad scores 0, 1 and 2 were calculated.

Differences between individual litter types with regard to carcass yield were determined using the two-way linear model of the ANOVA:

y jkl = µ + s j + l k + e jkl

where: y jkl – phenotypic value of the trait for the lth group of chickens, of jth sex, in the kth litter, µ – mean value of the trait for a given population, s j – effect of jth sex (j = 1, 2), l k – effect of kth litter (k = 1, 2, 3), e jkl – effect of experimental error.

Differences between individual litter types with regard to haemoglobin saturation were separately evaluated in males and females using the one-way linear model of ANOVA:

y jk = µ + l j + e jk

where: y jk – phenotypic value of the trait for the kth group of chickens, on the jth litter, µ – mean value of the trait for a given population, l j – effect of the jth litter (j = 1,2,3), e jk – effect of experimental error.

For all traits, the significance of differences between means for groups was verified using Fisher’s test. Phenotypic correlation coefficients (Pearson’s) for body weight of broilers and haemoglobin saturation were calculated separately for each sex.

Results

Performance

The performed investigations revealed (Table 1) that broi­ler chickens kept on wood shavings were characterised by higher body weights at the end of the rearing period (day 42) than the birds maintained on wheat straw and chopped wheat straw. This difference was significant and, on average, amounted to 135 g. Although, no differences were observed concerning body weight gains and feed intake by chickens kept on different litter types, a trend was noticed for better values of these traits in chickens maintained on wood shavings. In comparison with the chickens kept on chopped straw, birds from wood shavings were characterised by a significantly, on average by 0.16 kg, smaller FCR. In addition, chickens maintained on wood shavings were characterised by the lowest mortality, although this result was not confirmed statistically. No differences were found between the examined litters regarding carcass yield of the experimental birds. On the other hand, the EPEF index of birds reared on litter of wood shavings showed distinctly higher values in comparison with the remaining litters. The differences were significant and, on average, amounted to 50 points.

Table 1. Performance and FPD in broilers reared on different types of litter Leistung und Pododermatitis-Grad von Broilern bei Haltung auf unterschiedlichen Einstreusubstraten Trait Litter wheat straw chopped wheat straw wood shavings Body weight at

42nd day of age (g) 2339 a 2356 a 2482 b SEM 25.3 23.7 22.6 Body weight gain (g/bird/day) 55.7 56.1 59.1 SEM 4.09 4.45 4.75 Feed intake

(g/bird/day) 95.4 99.8 95.6 SEM 8.26 7.45 8.33 FCR

(kg/kg b.w.) 1.71 ab 1.78 b 1.62 a SEM 0.07 0.06 0.06 Mortality

(%) 4.3 3.2 3.1 SEM 0.04 0.03 0.04 Carcass yield

(%) 75.9 76.2 74.7 SEM 0.29 0.39 1.16 EPEF

(points) 312 a 304 a 358 b SEM 16.7 18.0 15.2 FPD

(points) 1.08 a 1.15 b 0.22 c SEM 0.02 0.02 0.01 Mean values designated in rows with different letters differ significantly at the level P ≤ 0.05

Analysing value changes of some performance parameters of the experimental broiler chickens it was demonstrated that birds maintained on the examined litters did not differ with regard to their body weight in weeks 1 to 5 (Figure 2). In weeks 1 to 4, no significant differences were recorded between litters regarding body weight gains of broilers (Figure 3). On the other hand, in week 5 of rearing, the best body weight gain was determined in birds kept on chopped straw and wood shavings. However, in the last week of experiments the best gains were recorded in broiler chickens maintained on wood shavings ( = 593 g/bird/day) and the worst – when birds were kept on chopped straw = 478 g/bird/day). No differences bet­ween chickens maintained on wheat straw, chopped wheat straw and wood shavings with regard to feed intake in individual weeks of life were found (Figure 4), although a tendency was observed for a worse value of this trait in weeks 2, 3, 4 and 5 when birds were kept on chopped straw.

Figure 2. Mean body weight of broilers kept on different kinds of litters Mittleres Körpergewicht der Broiler bei Haltung auf verschiedenen Einstreusubstraten

Figure 3. Mean body weight gain of broilers kept on different kinds of litters Mittlere Körpergewichtszunahmen der Broiler bei Haltung auf verschiedenen Einstreusubstraten

Figure 4. Mean feed intake of broilers kept on different kinds of litters Mittleres Futteraufnahme der Broiler bei Haltung auf verschiedenen Einstreusubstraten

Food-pad dermatitis

Broiler chickens maintained on wood shavings were characterised by significantly better (by about 80.3%) leg health condition as expressed by a smaller (by about 0.90 point) number of points in the 3-point scale (Table 1). Moreover, birds reared on wood shavings were characterised by the smallest FPD in individual weeks of life (Figure 5). Birds kept on chopped straw were characterised by the worst leg health condition in the period from week 4 to week 6 of rearing. Analysing the frequency of food-pad lesions (Table 2), it was found that, in the case of wheat straw and chopped wheat straw litter, the highest number of birds showed intermediate foot-pad lesions (1 point) amounting, on average, to 58.6%. On the other hand, up to 78.4% broilers kept on wood shavings were found to have no inflammatory changes of their foot-pads (0 points).

Figure 5. Foot-pad dermatitis (FDP) in broilers kept on different kinds of litters Pododermatitis-Grad der Broiler bei Haltung auf verschiedenen Einstreusubstraten

Table 2. Prevalence of foot-pad dermatitis in broiler chickens reared on different types of litter Häufigkeit an Pododermatitis bei Broilern bei Haltung auf unterschiedlichen Einstreusubstraten Points Litter wheat straw chopped wheat straw wood shavings % no of birds % no of birds % no of birds 0 – Lack of lesions 15.8 171 13.8 149 78.4 847 1 – Mild lesions 60.3 651 56.9 615 21.3 230 2 – Serious and deep lesions 23.9 258 29.3 316 0.3 3

Haemoglobin saturation

It was found that males kept on chopped straw and wood shavings had similar haemoglobin saturation amounting, on average, to 86.2% (Table 3). The lowest haemoglobin saturation was determined in males maintained on wheat straw. Similar tendencies regarding the value of this trait were also determined in females. Both in males as well as in females a negative, albeit not significant, correlation was determined between body weight and haemoglobin saturation (r p = from – 0.218 to – 0.229).

Table 3. Haemoglobin saturation levels in male and female reared on different types of litter Hämoglobinsättigung bei männlichen und weiblichen Broilern bei Haltung auf unterschiedlichen Einstreusubstraten Trait Litter wheat straw chopped wheat straw wood shavings haemoglobin saturation (%) 75.3 a 88.2 b 84.1 ab (males) SEM 1.94 4.61 3.3 haemoglobin saturation (%) 73.2 85.6 83.1 (females) SEM 6.16 2.06 4.03 Mean values designated in rows with different letters differ significantly at the level P ≤ 0.05

Litters chemical analysis

The performed analysis of the examined litters (Table 4) revealed that wood shavings were characterised by the lowest moisture content (the highest content of dry matter). All the experimental litters showed acid reaction (mean pH = 5.37), with the smallest pH value and nitrogen content determined in chopped straw.

Table 4. Some quality parameters of analyzed kind of litters Einige Qualitätskriterien der untersuchten Einstreusubstrate Trait Litter wheat straw chopped wheat straw wood shavings pH 5.56 5.10 5.44 dry matter (%) 38.20 39.10 41.80 Total nitrogen (% d.m.) 2.46 2.14 2.20 Ammonium nitrogen

(% d.m.) 0.923 0.399 0.561

Discussion

The performed investigations demonstrated that the broi­ler chickens were characterised by a higher final (day 42 of life) body weight when they were maintained on wood shavings than on the remaining two kinds of litters. Results similar to those obtained by the authors were also recorded by Davasgaium and Ogman after Sharnam et al. (2008) who reported higher body weights of chickens reared on wood shavings ( = 2,262 g) than on chopped wheat straw ( = 2,235 g) and ( = 2,040 g) wheat straw. On the other hand, Elwinger and Svensson (1996) failed to find significant differences in body weights of 35 and 40-day old chickens reared on wheat straw and wood shavings. Similar results were reported by Meluzzi et al. (2008) who ana­lysed body weights of broilers kept on straw and wood shavings on days 43 and 49 of life. In the case of both dates, they obtained similar mean body weights of the exa­mined birds on the above-mentioned litters amounting to 2,751 and 3,233 g, respectively.

Although the authors failed to show significant differences between the examined kinds of litter regarding mean daily body weight gains and feed intake in the entire period of broiler rearing, nevertheless values of these traits tended to be better when experimental birds were kept on wood shavings. Meluzzi et al. (2008) reported slightly higher body weight gains of broiler chickens maintained on wheat straw and wood shavings amounting to 62.4 and 62.7 g/bird/day, respectively, than in our own investigations, although they failed to find significant differences between litters regarding this trait. On the other hand, Sogunle et al. (2006) who conducted their experiments on different broiler chickens (Anac, Arbor acres, Hybro) reared on wood shavings reported lower results concerning bird feed intake ( = 72.8 g/bird/day) than those obtained in our studies. It is worth noting that the final body weight of chickens (44th day of life) from the above mentioned experiment was distinctly lower than in our studies and, on average, amounted to 1,644 g. Monira et al. (2003) failed to record any influence of the litter applied in broiler rearing on feed consumption results.

The lowest feed consumption was determined in the group of chickens maintained on wood shavings and their significantly higher final body weight translated into lower FCR in comparison with the birds reared on chopped straw. On the other hand, the results on chopped straw obtained by Pedersen and Thomson (2000) were similar to those recorded on wood shavings in our experiments and, on average, amounted to 1.64 kg/kg body weight, but the chickens were kept up to the 38th day of life and mean slaughter body weight of 1834 g. Swain and Sundaram (2000) failed to observe differences in FCR when comparing the results obtained by broilers kept on the following kinds of litter: rice husks, sawdust and coir dust. On the other hand, Biswas et al. (2001) reported worse FCR by chickens kept on wheat straw than sawdust.

Analysing the mortality of experimental birds which did not exceed current standards, no differences in the applied kinds of litter were recorded, although Dozier III et al. (2006), while maintaining chickens on wood shavings up to the 35th day of life and 1,838 g mean body weight, recorded lower mortality than those obtained in our studies on this litter (1.9 against 3.1%). On the other hand, mortality of chickens kept on leaf litter was by 4 percentage points higher, although this difference was not confirmed statistically. Despite the fact that Monira et al. (2003) did not show differences between litter applied in their experi­ment (wheat straw, sawdust, sugarcane bagasse and rice husk) with regard to the number of deaths, nevertheless they noticed a trend for better results when birds were maintained on sawdust.

No data was found in the available literature on com­paring effects of wheat straw and wood shavings on slaughter traits and economical results of rearing. Sharnam et al. (2008) found similar values of carcass yield and EPEF when broiler chickens were kept on rice husks and litter made up of a mixture of wheat straw and sawdust, although slightly lower, albeit non-significant, values of the EPEF index were recorded for broilers reared on the straw and sawdust mixture which could be attributed to a smaller final body weight (by about 63 g) and worse FCR (on average by about 65 g/kg b.w.) by birds from this group. In our experiments, no differences were found between litter types with regard to carcass yield of birds but significantly better results of production profitability were recorded when broilers were kept on wood shavings (EPEF = 358 points). Also Willis et al. (1997) failed to find differences in carcass yield of chickens comparing the results obtained for broilers kept on wood shavings and leaf litter ( = 69.3%).

The evaluation of the leg health condition revealed that chickens maintained on wood shavings were characterized by distinctly less advanced development of FPD than birds reared on the experimental straw litters. Also Ekstrand et al. (1997) reported FPD frequency similar to our findings confirming wood shavings as the best kind of litter, although these results were not confirmed statistically. On the other hand, the above researchers demonstrated a significant impact of the depth of the litter material on leg health. Martrenchar et al. (2002) observed the same frequency of FPD occurrence (of about 20%) in broiler chickens maintained on different litter depths, i.e. < 5 cm and between 5 and 10 cm. Similarly to our experiments, in trials conducted on broiler chickens and turkeys, the above researchers recorded lower percentage proportion of birds characterized by foot lesion ranging, respectively, from 13 to 3% when they were kept on wood shavings. In the case of wheat straw, FPD was found for 74 and 69% of the examined broiler group. Similarly, Meluzzi et al. (after Meluzzi and Sirri, 2009) determined FPD reduced by about 35% in broilers kept on wood shavings in comparison with straw. The prevalence and severity of FPD can also be affected, apart from the litter itself, by the stocking rate of birds and appropriate feeding, including the applied types of feeders and drinking fountains (Martren­char 1997 and 2002). However, no correlations were determined between the incidence of FPD and body weight of broilers (Kjaer et al., 2006). In our experiments, the maintenance conditions as well as the applied feeding system and feed supply were identical for all groups of birds. Therefore, it appears that it was primarily the lower moisture content of the substrate that affected directly better results regarding the incidence of FPD in heavier chickens kept on wood shavings. Also Dawkins et al. (2004) reported correlations between wet litter and soiling of foot-pads. The higher the moisture content of the substrate, the dir­tier and less healthy the legs of birds were found to be. Better performance effects of broiler chickens reared on wood shavings determined in our experiments could have indirectly resulted from better health condition of their legs. Martland (1985) demonstrated lower body weight gains of broilers characterized by serious FPD. The same researcher also reported relationships between increased litter moisture content as well as lower body weights and higher FPD incidence.

The performed investigations revealed, especially in the case of males, better blood oxygenation (higher percent of SaO 2 ) when the birds were reared on wood shavings and chopped wheat straw. However, the obtained results of haemoglobin saturation were by about 10.0 percentage points lower in comparison with those reported by Julian and Mirsalimi (1992) for broilers of mean body weight of 2,285 g. It should be mentioned that the above researchers, similarly to our own investigations, demonstrated that heavier chickens ( = 3,481 g) were characterised by significantly lower haemoglobin saturation amounting to about 86.0% when measured by a pulse-oximeter. Complex investigations carried out on different chicken lines (Buys et al., 1999; Olkowski et al., 1999) revealed that fast-growing birds were usually characterised by a lower FCR, lower partial oxygen pressure (pO 2 ) and lower oxygen haemoglobin saturation (SaO 2 ) which may be, among others, a cause of the occurrence of hypoxemia in them. In our experiments a negative, albeit non-significant, correlation was found between body weight of experimental broilers and haemoglobin saturation. On the other hand, Julian and Mirsalimi (1992) found a significantly negative correlation between broiler body weight and haemoglobin saturation. Despite the fact that in our experiments broiler chickens maintained on wood shavings were characterised by better growth, lower FCR and higher final body weight, no deterioration in their haemoglobin saturation was observed.

Conclusions

Recapitulating, it can be stated that the type of litter adopted to broiler chickens rearing had influence on performance parameters and birds health. It was shown, i.a. that broiler chickens kept on wood shavings were characterised by the highest body weight and simultaneously the smallest feed conversion ratio. Birds maintained on the same type of litter had also lower lesions of foot-pads, which was probably affected by lower wood shaving humidity.

References

Biswas, S.K., M.A. Wahid, M.J. Karim, M.A.H. Pramanik, M. Rokonuzzaman, 2001: Evaluation of different litter materials for broiler performance, coccidial oocyst population and level of N, P and K during winter. Pakistan J Biol. Sci. 4, 1565-1567.

Buys, N., C.W. Scheele, C. Kwakernaak, J.D. van der Klis, E. Decuypere, 1999: Performance and physiological variables in broiler chicken lines differing in susceptibility to the ascites syndrome: 1. Changes in blood gases as a function of ambient temperature. Brit. Poult. Sci. 40, 135-139.

Campo, J.L., M.G. Gil, S.G. Davila, I. Munoz, 2005: Influence of perches and footpad dermatitis on tonic immobility and heterophil to lymphocyte ratio of chickens. Poult. Sci. 84, 1004-1009.

Dawkins, M.S., C.A. Donnelly, T.A. Jones, 2004: Chicken welfare is influenced more by housing conditions than by stocking density. Nature 427, 342-344.

Dozier III, W.A., J.P. Thaxton, J.L. Purswell, H.A. Olanrewaju, S.L. Branton, W.B. Roush, 2006: Stocking density effects on male broilers grown to 1.8 kilograms of body weight. Poult. Sci. 85, 344-351.

Ekstrand, C., B. Algers, J. Svedberg, 1997: Rearing conditions and foot-pad dermatitis in Swedish broiler chickens. Prevent. Vet. Med. 31, 167-174.

Ekstrand, C., T.E. Carpenter, I. Andersson, B. Algers, 1998: Prevalence and control of foot-pad dermatitis in broilers in Sweden. Brit. Poult. Sci. 39, 318-324.

Elwinger, K., L. Svensson, 1996: Effect of dietary protein content, litter and drinker type on ammonia emission from broiler houses. J. Agri. Engin. Res. 64, 197-208.

Goetsch, A.L., N.B. Anthony, M.A. Woodley, G.T. Tabler, 1998: Chemical constituents in broiler litter in two areas of a production unit after different numbers of growing periods. Bioresource Tech. 65, 151-157.

Greene, J.A., R.M. McCracken, R.T. Evans, 1985: A contact dermatitis of broilers – clinical and pathological findings. Avian Pathology 14, 23-38.

Hester, P.Y., D.L. Cassens, T.A. Bryan, 1997: The applicability of particleboard residue as a litter material for male turkeys. Poult. Sci. 76, 248-255.

Imaeda, N., 2000: Influence of the stocking density and rearing season on incidence of sudden death syndrome in broiler chickens. Poult. Sci. 79, 201-204.

Ivanov, I.E., 2001: Treatment of broiler litter with organic acids. Res. Vet. Sci. 70, 169-173.

Julian, J., S.M. Mirsalimi, 1992: Blood oxygen concentration of fast-growing and slow-growing broiler chickens, and chickens with ascites from right ventricular failure. Avian Dis. 36, 730-732.

Kjaer, J.B., G. Su, B.L. Nielsen, P. Sorensen, 2006: Foot-pad dermatitis and hock burn in broiler chickens and degree of inheritance. Poult. Sci. 85, 1342-1348.

Kranen, R.W., C.H. Veerkamp, E. Lambooy, T.H. van Kuppevelt, J.H. Veerkamp, 1998: The effect of thermal preslaughter stress on the susceptibility of broiler chickens differing with respect to growth rate, age at slaughter, blood parameters, and ascites mortality, to hemorrhages in muscles. Poult. Sci. 77, 737-744.

Martland, M.F., 1984: Wet litter as a cause of plantar pododermatitis, leading to foot ulceration and lameness in fattening turkeys. Avian Pathology 13, 241-252.

Martland, M.F., 1985: Ulcerative dermatitis in broiler chickens: the effects of wet litter. Avian Pathology 14, 353-364.

Martrenchar, A., E. Boilletot, D. Huonnic, F. Pol, 2002: Risk factors for foot-pad dermatitis in chicken and turkey broilers in France. Prev. Vet. Med. 52, 213-226.

Martrenchar, A., J.P. Morisse, D. Huonnic, J.P. Cotte, 1997: Influence of stocking density on some behavioural, phy­siological and productivity traits of broilers. Vet. Res. 28, 473-480.

McGovern, R.H., J.J.R. Feddes, F.E. Robinson, J.A. Hanson, 1999: Growth performance, carcass characteristics, and the incidence of ascites in broilers in response to feed restriction and litter oiling. Poult. Sci. 78, 522-528.

Meluzzi, A., C. Fabbri, E. Folegatti, F. Sirri, 2008: Effect of less intensive rearing conditions on litter characteristics, growth performance, carcase injuries and meat quality of broilers. British Poultry Science, 49, 509-515.

Meluzzi, A., F. Sirri, 2009: Welfare of broiler chickens. Italian J. Anim. Sci. 8 (suppl. 1), 161-173.

Monira, K.N., M.A. Islam, M.J. Alam, M.A. Wahid, 2003: Effect of litter materials on broiler performance and eva­luation of manureal value of used litter in late autumn. Asian-Australasian J. Anim. Sci. 16, 555-557.

Olkowski, A.A., D. Korver, B. Rathgeber, H.L. Classen, 1999: Cardiac index, oxygen delivery, and tissue oxygen extraction in slow and fast growing chickens, and in chickens with heart failure and ascites: a comparative study. Avian Pathology 28, 137-146.

Peacock, A.J., C. Pickett, K. Morris, J.T. Reeves, 1990: Spontaneous hypoxaemia and right ventricular hypertrophy in fast growing broiler chickens reared at sea level. Comp. Bioch. Physiol. A, Comp. Physiol. 97, 537-541.

Pedersen, S., G.M. Thomson, 2000: Heat and moisture production of broilers kept on straw bedding. J. Agric. Engin. Res. 75, 177-187.

Sharnam, K.S., K.N. Wadhwani, K. Khanna, A.M. Patel, 2008: Effect of quality feeds and litter materials on broiler performance under hot humid climate. Inter. J. Poult. Sci. 7, 14-22.

Sogunle, O.M., B.A. Ogunjimi, A.O. Fanimo, 2006: Effect of litter depth on the performance of three strains of broiler chickens. J. Anim. Vet. Advances 5, 1155-1157.

Swain, B.K., R.N.S. Sundaram, 2000: Effect of different types of litter material for rearing broilers. Brit. Poult. Sci, 41, 261-262.

Terzich, M., C. Quarles, M.A. Goodwin, J. Brown, 1998: Effect of Poultry Litter Treatment® (PLT®) on the develop­ment of respiratory tract lesions in broilers. Avian Pathol. 27, 566-569.

Wideman, R.F., 2001: Pathophysiology of heart/lung disorders: pulmonary hypertension syndrome in broiler chickens. World’s Poult. Sci. J. 57, 289-307.

Willis, W.L., C. Murray, C. Talbott, 1997: Evaluation of leaves as a litter material. Poult. Sci. 76, 1138-1140.

Zuidhof, M., J. Feddes, R. McGovern, F. Robinson, J. Hanson, 1997: Environmental factors can affect ascites in broiler chickens. Poult. Res. Centr. News 6, http://www1.agric.gov.ab.ca/ department/deptdocs.nsf/all/pou3576.