THERMOGRAPHIC EVALUATION OF THE EFFECT OF CELLULOSE ADDED TO STRAW LITTER ON THE TEMPERATURE OF BEDDING

Oryna Słobodzian-Ksenicz¹, Jacek Bojarski^2
1 Faculty of Civil and Environmental Engineering, University of Zielona Góra, Poland
² Faculty of Mathematics, Computer Science and Econometrics, University of Zielona Góra, Poland

ABSTRACT

The objective of the study was to determine the effect of the addition of cellulose to the straw litter on the temperature of the bedding in the turkey house by means of thermographic photography. The study was conducted in a turkey house which is structurally divided into two separate sectors: SB (straw bedding – control) with a 10-cm layer of rye straw bedding and CB (cellulose bedding) with a 5-cm layer of rye straw bedding strewn with a 5-cm layer of cellulose from coniferous wood. 1200 day-old BIG 6 turkey hens were placed in both sectors. The production cycle parameters in both sectors were the same. The study consisted of 8 measurement sessions. During each measurement session 12 photographs were taken with a thermovision camera V-20 II. In order to stabilize the temperature of the bedding and prevent the birds from accessing the research area, 3 fibre-board rings were lowered on the litter in the respective sectors. Also complementary observation was conducted regarding the rate of surface encrustation of the bedding types. Basing on the collected data it has been determined that CB was characterized by higher temperature values throughout the production cycle than SB, except for week 8. Higher temperatures in CB as compared to SB indicate that the cellulose bedding was characterized by better thermal properties. The exothermic processes taking place in CB generated energy, which was an additional factor in the drying of the litter, which had a positive effect on its quality (f.ex. by reducing the rate of surface encrustation). The histogram analysis indicates that the CB surface was characterized by a more uniform distribution of temperature than SB.

Key words: litter, cellulose, straw, thermovision, turkey.

IMPLICATIONS

In poultry rearing warmth retention and the hygiene of the bedding are of importance as the birds remain in direct contact with it throughout the production cycle. To improve the sorptive properties of straw – the most commonly used bedding material – a variety of supplements are added [15]. In this study cellulose C6H12O6 was applied – a natural, odourless, non-toxic and highly sorptive supplement. The addition of cellulose improved the sorptive and thermal properties of the straw bedding and slowed down the process of encrustation, which enabled faster moisture evaporation. The application of cellulose improved the animals' well-being and proved beneficial in terms of production results. In order to determine the influence of the addition of cellulose on the thermal properties of the bedding a fast, noninvasive, precise and objective thermovision method was applied.

INTRODUCTION

The most common system of rearing animals in poultry production is the deep litter system [2]. Good litter material should among other properties have low thermal conductivity and retain the heat [1]. It should also be characterized by high moisture absorbency and the ability to evaporate water since moist litter is cold and is subject to fast surface encrustation [8, 10] and has negative effect on animals and the microclimate in the house [11, 20]. Air quality, hygiene problems and zootechnical problems within livestock buildings are often linked to the bedding material and bedding management [7].The quality and temperature of the bedding are very important as the birds are in direct contact with it throughout the production process [3].

The optimization and stabilization of rearing conditions is essential not only at the beginning of the production cycle, when the animals impose demanding requirements regarding thermal conditions and exhibit poor adaptation skills, but also throughout the production cycle, as currently-reared broilers are less tolerant of unfavourable environmental factors [10, 12, 19].

The most frequently used litter materials are straw and wood shavings. Over the past few years, however, wood shavings have become harder to acquire due to periodic supply shortages and the increasing price [8]. Straw is characterized by very average sorption properties and therefore straw bedding is supplemented with a variety of additives aimed at improving the quality of the bedding and the microclimate by f.ex. reducing the emission of ammonia [4, 5, 14, 15]. The effect of adding brown coal and the EM1 bacterial vaccine on the thermal properties of straw bedding was discussed in the previous article by the present authors [16].

In relevant literature on the subject there are no references to cellulose as an additive to the litter and its effect on the thermal properties of the bedding. Cellulose – C₆H₁₂O₆ – an organic compound (polysaccharide) of natural origin, non-toxic, odourless and of very good sorption properties, does not exert any negative influence either on the environment in the house or the birds themselves. When it is then found in the manure, cellulose will serve as an additional source of organic carbon.

The objective of the study was to determine the effect of the addition of cellulose to straw litter on the temperature of the bedding in the turkey house during the production cycle.

MATERIAL AND METHODS

The study was conducted at an operating Poultry Farm in Kaczenice near Zielona Góra (in Poland) in autumn-wintertime. The livestock facility – the turkey house – in which the study was carried out is structurally divided into two sectors, 550 m² of area each. The first sector SB (straw bedding – control) was laid with a 10-cm layer of compact rye straw. The other sector CB (cellulose bedding) was laid with a 5-cm layer of compact rye straw strewn with a 5-cm layer of cellulose from coniferous wood. Subsequently, in each sector respectively, 6000 day-old BIG 6 turkey hens were placed on the bedding types as described above. The systems of watering, feeding, heating, ventilation, the lighting programme and the air temperature values in both sectors in the consecutive weeks of the production cycle were the same. In order to reduce the amount of dust in the sector with cellulose, starting with week 5 of the production cycle the cellulose bedding was strewn with a 0.5–1 cm layer of straw. At week 7 of the growing stage the stock’s density was reduced. The production period lasted 15 weeks. In order to stabilize the temperature of the bedding and prevent the birds from accessing the research area, always two hours before the photographs were taken, 3 fibre-board rings, 1.9 m in diameter each, were lowered on the litter in the respective sectors, always in the same place. During the study 8 measurement sessions were held: the first session at week 0 – after 36 hours of heating and before the turkey placement, the subsequent sessions – at weeks 2, 4, 6, 8, 10, 12 and 14 of the production cycle. During each measurement session, at the height of 1.3 m, 12 photographs were taken with the V-20 II thermovision camera (manufacturer: VIGO Systems S.A.) with the thermal resolution of NETD 0.05ºC. To analyze the thermographic data the THERM V – 20 programme was used, by means of which the minimal, maximum and mean temperature values were read for the photographed area [0.9 m²] and respective histograms were made. During the measurement sessions throughout the production cycle the photographs were always taken on the same week-day and at the same time of day (between 08:00 and 11:00 a.m.) in order to avoid any differences resulting from the effect of poultry management jobs, especially those to do with the bedding. Additionally, control measurements of the air temperature and humidity inside (in the rearing area) and outside the house were taken. The measurements were taken at the height of 0.5 m inside the house and at the height of 2 m outside the house. Over the consecutive weeks of the production cycle the rate and degree of surface encrustation of the cellulose and straw bedding were also determined along a 10-point scale (0 – no encrustation, 10 – 100% encrustation of the bedding surface). Complementary observations of the birds’ behavior were also made [17]. In order to conduct chemical analyses of the bedding’s moisture etc., once the bedding was laid and before the house was heated as well as after the production cycle was finished, samples of the cellulose and straw bedding were taken (PN-R-04006, 2000; PN-A-74011, 1986).

The t-Studenta test was used to make a comparison of the mean values of the temperature of the studied bedding types in the consecutive weeks of the production cycle. A null hypothesis was formulated that there is no substantial difference in the mean values of temperature between the cellulose and the straw bedding (CB = SB). An alternative hypothesis (alt.) assumed that the mean values of temperature of the cellulose bedding are substantially higher than those of the straw bedding (CB > SB) and that the mean values of the temperature of the cellulose bedding are substantially lower than those of the straw bedding (CB < SB).

RESULTS

Throughout the study the discussed temperature values refer to the mean values of temperature of the studied bedding types.

Figures 1 and 2 present examples of the thermographic photographs and histograms of the cellulose and straw bedding before bird placement.

Figures 3 and 4 present the examples of the thermographic photographs and histograms of the cellulose and straw bedding at week 10. of the production cycle.

The selected photographs presented above show that both before bird placement and at week 10. of the fattening stage the surface of the cellulose bedding was characterized by a higher mean temperature than the straw bedding. The histograms in turn demonstrate that the cellulose bedding had a more uniform distribution of temperature as compared to the straw bedding.

Table 1 compares the results of the t-Student test verifying the formulated hypotheses. The null hypothesis based on the assumption that there is no substantial difference in the mean values of temperatures between the studied bedding types has been rejected. The alternative hypotheses assuming that the mean values of temperatures of the respective bedding types have been confirmed.

Figure 5 presents the mean values of temperatures of the CB and SB surfaces as recorded in the thermographic photographs taken in the consecutive weeks of the production cycle. These are mean values computed from 57 600 measurement points composing a single photograph.

With similar levels of moisture of the bedding materials (cellulose – 8.5%, straw 8.8%) the mean value of temperature of CB surface before bird placement (series 0) was higher by 1.1 K than SB. It was however statistically insignificant due to a very high standard deviation on SB (s.d. 3.06).

At weeks 2., 4. and 6. of the production cycle the mean values of CB temperatures were higher than SB by 0.8 K, 2.7 K and 1.1 K respectively. The temperature differences at weeks 2. and 4. were statistically significant.

Throughout the production cycle only at week 8. CB temperature was lower than SB. The difference of 1.7 K was however statistically insignificant due to a very high standard deviation on CB (s.d. 2.63).

At weeks 10. and 12. of the production cycle the cellulose bedding had higher temperatures than the straw bedding by 2.2 K and 2.0 K respectively. These differences were statistically significant.

At week 14., the last week of the study, despite higher moisture (RH 56.5%), the cellulose bedding was characterized by a higher (by 0.9 K) temperature than the straw bedding (RH 47.2%). This difference was statistically significant.

Throughout the production cycle a decline in mean values of temperatures in both types of bedding was recorded – 15.8 K for CB and 15.6 K for SB. A gradual decline in surface temperature of the bedding is beneficial in the production cycle as growing animals are less particular about thermal conditions and themselves become a source of heat, which they can give up to the colder litter [13].

Table 2 compares the spans (R) of mean values of minimal and maximum temperatures of the surfaces of the studied bedding types in the consecutive weeks of the production cycle.

Before bird placement and at weeks 2., 4., 6., 8., 10. and 12. of the production cycle CB was characterized by a narrower span of minimal and maximum temperatures than SB. Only at week 14., the last week of the study, CB was characterized by a wider span of minimal and maximum temperatures than SB. The narrower span of minimal and maximum temperatures of the CB surface (from 1.71°C to 3.42°C) as compared to SB surface (from 1.98°C to 4.80°C) points to a more uniform temperature of the CB surface in the consecutive weeks of growing and fattening stages (with the exception of week 14.). The histogram analysis confirms that throughout the production cycle the CB surface was characterized by a more uniform temperature distribution than SB. The results of the observation of the rate of surface encrustation indicate that the process progressed much more slowly on CB than SB. It was not until week 7. that the first signs of surface encrustation were found on CB, compared to week 4. for SB. At week 11. the whole area of the straw bedding was covered with a layer of crust, compared to week 14., the last week of the production cycle, for the cellulose bedding [17]. During the experiment attention was paid to the birds’ behaviour regarding their interest in the surroundings, mobility, need for ‘bathing’ and scratching the bedding. It was found that in the sector with cellulose the turkeys were definitely more mobile, took more interest in the bedding, scratched it and even bathed in it (behaviour untypical of turkeys). Similar behaviour was not observed in the sector with straw [17].

DISCUSSION AND CONCLUSIONS

The conducted study has shown that the thermographic technology can be helpful in evaluating the thermal properties of the types of bedding used in animal husbandry as well as in analyzing the processes taking place in them.

Summing up the conducted analysis of the study results it has been determined that before bird placement and with similar moisture levels of the litter materials – cellulose (8.5%) and straw (8.8%), the cellulose bedding was characterized by a higher and more uniform surface temperature (s.d. 1.67 for CB and 3.06 for SB) than the straw bedding.

From a breeding standpoint higher temperatures of the bedding’s surface at the early stage of the production cycle (growing) are very important regarding higher thermal requirements of young birds and a more even temperature is beneficial for a more uniform distribution of animals over the whole area of the house.

The histogram analysis confirms that the temperature of the cellulose bedding was characterized by a more uniform distribution of temperatures than the straw bedding.

Throughout the production cycle the cellulose bedding was characterized by higher temperature values than the straw bedding except for week 8, when the difference (1.7K) was statistically insignificant. The most likely reasons for this relationship were accidental external factors, limited only to the sector with the cellulose litter, which had to do with the reduction in stocking density at week 7.

The recorded differences in the mean values of temperatures between the cellulose and straw bedding were statistically significant:

1. at week 2. (difference 0.8 K) at P < 0.05
2. at week 4. (difference 2.7 K) at P < 0.01
3. at week 10. (difference 2.2 K) at P < 0.001
4. at week 12. (difference 2.0 K) at P < 0.01
5. at week 14. (difference 0.9 K) at P < 0.001.

In the consecutive weeks of growing and fattening stages a steady decline in the temperature of both types of bedding was recorded, this being sharper in the cellulose bedding than the straw bedding, except for weeks 2. and 8. A decline in surface temperature of the bedding is beneficial as growing animals are less particular about thermal conditions and themselves become a source of heat, which they can give up to the colder litter. The higher temperatures of the cellulose bedding as compared to the straw bedding indicate that the cellulose bedding was characterized by better thermal properties and that there were exothermic processes taking place in the cellulose bedding. The warmth in litter is produced by bacterial fermentation and partly direct contact with birds [9]. Higher temperatures stimulate microbial activity [6] and apart from that the generated energy was an additional factor in the drying of the bedding and had a positive influence on its quality, by f. ex. delaying the process of encrustation [18]. The crust appeared on the straw bedding at week 4. and at week 11. it already covered 100% of the area, whereas on the cellulose bedding the first signs of encrustation were observed at week 7. and 100% encrustation was not observed until week 14., the last week of fattening [17]. After the production cycle was finished, the recorded higher moisture of the cellulose bedding (by 9.3 percentage points) had no negative effect on its condition since it resulted from better moisture absorbency of the cellulose bedding than the straw bedding and the slowed down encrustation enabled the evaporation of the moisture. An additional factor contributing to the drying of the cellulose bedding were the birds scratching and bathing in it [17].

Accepted for print: 22.07.2014

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