University of Veterinary Medicine Hannover
Enriched charcoal as feed additive in the nutrition of commercial broiler chickens and male fattening turkeys
kept under on-farm conditions
Inaugural Dissertation to obtain the academic degree Doctor medicinae veterinariae
(Dr. med. vet.)
submitted by Katharina Hinz
born in Crivitz
Hannover 2019
Academic supervision: Academic supervision:
Prof. Dr. med. vet. Nicole Kemper
Institute for Animal Hygiene, Animal Welfare and Farm Animal Behaviour
University of Veterinary Medicine Hannover Further members of the supervision group:
Dr. med. vet. Birgit Spindler
Institute for Animal Hygiene, Animal Welfare and Farm Animal Behaviour
University of Veterinary Medicine Hannover
1. Referee: Prof. Dr. med. vet. Nicole Kemper
Institute for Animal Hygiene, Animal Welfare and Farm Animal Behaviour
University of Veterinary Medicine Hannover
2. Referee: Prof. Dr. med. vet. Silke Rautenschlein Clinic for Poultry
University of Veterinary Medicine Hannover
Day of the oral examination: 07.11.2019
This research was conducted within the EIP Agri Project “CarboFeet” which is funded by the European Union and the European Agricultural Fund for Rural Development (EAFRD).
To my family
The author contributed substantially to the methodology, the investigations, the formal analysis, the visualisation, the writing and original draft preparation of the included publications.
Index
1. General Introduction ... 7
2. Publications ... 11
2.1 Foot Pad Health and Growth Performance in Broiler Chickens as Affected by Supplemental Charcoal and Fermented Herb Extract (FKE): An On-farm Study .. 11
2.2 Effects of Enriched Charcoal as Permanent 0.2 % Feed-Additive in Standard and Low-Protein Diets of Male Fattening Turkeys: An On-Farm Study ... 13
3. General Discussion ... 15
4. General Conclusion ... 21
5. General Summary ... 22
6. Zusammenfassung ... 24
7. List of publications... 27
8. References ... 28
9. Acknowledgements ... 37
Introduction 7
1. General Introduction
In poultry farming, maintaining intestinal health is an important issue. Indeed, this affects growth performance, litter quality and animal welfare of the birds. One approach to maintaining gut health is the use of charcoal as a feed additive. Charcoal is a product of the pyrolysis of carbon-rich materials, such as wood. As a result of this process, a porous structure is formed, with interconnected pores comparable to a sponge. These pores vary in size and create a high inner surface. Hence, charcoal is a non-specific absorber with high absorption capacities (Girgis et al., 2002). Due to this characteristic, charcoal has a wide range of application possibilities, e.g. in drinking water treatment (Simazaki et al., 2008), air purification (Doyle et al., 1977) and medicine (Eddleston et al., 2008). Since ancient times, humans have used charcoal for medical issues such as epilepsy, splenic fever and intoxications (Robens, 2010). In Zanzibar, in Red Colobus Monkeys, the autonomous consumption of charcoal was observed and assessed as being beneficial for the digestion of phenolic-rich leaves (Struhsaker et al., 1997). A comparable phenomenon could be observed in ruminants, where a charcoal-supplemented diet increased the intake of juniper (Bisson et al., 2001), sagebrush (Banner et al., 2000; Villalba et al., 2002) and some Mediterranean shrubs (Rogosic et al., 2009). The digestion of these plants is known to be limited due to the contents of terpenes, saponins, tannins and other secondary compounds. Charcoal is suitable for treating intoxication cases and diarrhoea due to its absorbing characteristics. It was proven an effective therapy in carprofen poisoning of dogs (Koenigshof et al., 2015) and in the poisoning of cattle with yellow tulip (Snyman et al., 2009). Furthermore, Paraud et al. (2011) and Watarai et al. (2008) found activated charcoal containing wood vinegar helpful in cryptosporidiosis treatment of goat kids and calves. It not only alleviated the diarrhoea but also reduced the excretion of Cryptosproridium parvum oocysts (Watarai et al., 2008). In Korean studies on feeding bamboo charcoal to pigs, an improved growth performance, feed efficiency and faecal microflora, as well as decreased noxious gas emission were found (Chu et al., 2013a;
Chu et al., 2013c). Moreover, dietary bamboo charcoal improved the carcass grade and the fatty acid composition of the meat of fattening pigs (Chu et al., 2013b). The
Introduction 8
study by Mekbungwan et al. (2004) indicates positive effects on villus height, cell area and cell mitosis in piglets by feeding charcoal mixed with wood vinegar. Furthermore, investigations of fish demonstrated that carbon is an effective treatment for improving growth performance, feed efficiency and intestinal morphology (Thu et al., 2010;
Boonanuntanasarn et al., 2014; Pirarat et al., 2015).
In poultry science, a lot of studies show positive effects of dietary charcoal as well. The growth performance and the feed conversion ratio of broiler chickens were enhanced in the investigations by Kutlu et al. (2001) and Majewska et al. (2011). Ruttanavut et al. (2009), Yamauchi et al. (2010) and Rattanawut (2014) found that bamboo charcoal including vinegar liquid improved histological intestinal parameters such as villus height, villus area, cell area and cell mitosis. These parameters are correlated with resorption and other functions of the intestine (Yamauchi & Tarachai, 2000). However, these studies could not confirm the positive effects on growth performance and feed efficiency. In a study by Kana et al. (2011), the weight gain was increased with 0.2 % and 0.4 % Canarium schweinfurtii seed charcoal, but not with maize cob charcoal. In turkeys, studies on charcoal as feed additive are rare, albeit in the studies by Majewska et al. (2002) and Majewska et al. (2009) where an improved growth performance, feed conversion ratio and mortality were described. Another positive aspect of carbon is the absorption of bacteria. Naka et al. (2001) found that activated charcoal binds Escherichia coli effectively in vitro. Furthermore, some investigations suggest that activated carbon could adsorb bacteria such as Escherichia (E.) coli and Salmonella species (Watarai & Tana, 2005; Rattanawut, 2014; Prasai et al., 2016) which are potential pathogens in poultry. With E. coli and Clostridium perfringens being very frequent intestinal diseases in poultry (Morgan et al., 2008; Persoons et al., 2012), the reduction of these microorganisms could decrease the morbidity rates of intestinal infections and the need for antibiotics. Adding wood vinegar liquids or fermented herb extracts to charcoal could increase this effect because their main components are organic acids (Ruttanavut et al., 2009; Rattanawut, 2014). These organic acids are known to inhibit the growth of bacteria (Anderson et al., 1991; Dibner & Buttin, 2002) and improve the growth performance (Namkung et al., 2004; Adil et al., 2010).
Introduction 9
In this study, it was hypothesised that charcoal absorbs faecal liquids and improves intestinal health which would reduce the litter moisture and decrease the incidence of foot pad dermatitis. In poultry, foot pad dermatitis is a frequently investigated issue due to its great relevance as an animal-related welfare indicator. It reflects factors of housing conditions directly seen on the birds’ skin. Foot pad dermatitis is characterised by lesions on the metatarsal pads which can spread to the digits. At first, the skin shows symptoms of inflammation and discolouration. At a later stage, hyperkeratosis of the epidermis evolves, and the posterior pathology is marked by erosion and ulcerations extending into deep layers of the dermis and the underlying tissue (Greene et al., 1985; Martland, 1985). Due to ascending infections, the quality of the carcass can be impaired and economic losses also result from reduced body weight gain (Martland, 1985). Foot pad dermatitis plays a role not only in the production quality but also in the animals’ welfare. The reduced body weight gain can be traced back to a pain-induced decrease in the feed intake (Shepherd & Fairchild, 2010). Based on the pathological alterations, foot pad dermatitis can be expected to be painful, with pain being a cardinal sign of inflammation (Celsus, 1935). Moreover, there is evidence that foot pad dermatitis influences the gait score negatively in broiler chickens (Harms &
Simpson, 1975; Hester, 1994). Therefore, it is important to reduce the incidence of foot pad dermatitis by improving the housing conditions. High litter moisture is a very important cause for the development of foot pad dermatitis in poultry (Harms et al., 1977; Youssef et al., 2011b; Taira et al., 2014). Wet litter can result from deficiencies in different parameters such as ventilation, housing climate, stocking density, dietary composition (e.g. protein, fat, salt), litter material and litter quality (Tucker & Walker, 1992; Haslam et al., 2007; Youssef et al., 2011b; Youssef et al., 2011a). Moreover, litter moisture can be influenced by inflammatory intestinal diseases and diarrhoea, for example caused by dysbacteriosis (Collett, 2012).
Another aspect for improving animal welfare is the reduction in crude protein content in the diet. In broiler chickens, this feeding strategy is known as slow growth diet, but in turkeys, similar diets are uncommon. Due to the lower protein content, the body weight gain in turkeys is reduced and, as a consequence, the breast muscle yield is decreased, which reduces economic efficacy (Plavnik & Hurwitz, 1988; Kidd et al.,
Introduction 10
1997). An approach to overcoming this disadvantage is to temporally limit the reduction which might result in compensatory growth. Auckland and Morris (1971) described compensatory growth in turkeys when observing increased growth after a period of malnutrition. The study by Zubair and Leeson (1996) showed this effect in broiler chickens as well. Moreover, reducing the amount of protein in the diet might help to lower the nitrogen emission. Due to the over-utilisation of litter for fertilisation, high densities of animal farms endanger the groundwater quality by contamination with nitrates (GALLOWAY et al., 2003; World Health Organization, 2003; Ward Mary, 2009). Nitrates can induce health issues such as colorectal cancer in humans (Schullehner et al., 2018).
The combination of charcoal and protein reduction might enhance this effect, even if there are no studies confirming this assumption yet. Moreover, all the cited experiments using charcoal were performed in experimental settings: the animals were mostly kept in individual cages or in small groups compared to the numbers used on commercial farms. Therefore, the housing conditions in these studies were different from the conditions on-farm, which complicates the transferability to the application of charcoal on commercial farms. There are several factors influencing the on-farm performance and the welfare of the animals. This requires studies to be performed under on-farm conditions, as weak impacts could be obscured. Thus, the aim of our study was to transfer the usage of enriched charcoal as 0.2 % feed additive in the diets of broiler chickens and fattening turkey toms to on-farm conditions. Besides economic factors, such as growth performance, the focus of this study was to explore the effects on foot pad health, hock burns and other parameters of the birds’ health. It was hypothesised that the enriched charcoal decreases faecal moisture, and as a consequence thereof, reduces foot pad dermatitis.
Publications 11
2. Publications
2.1 Foot Pad Health and Growth Performance in Broiler Chickens as Affected by Supplemental Charcoal and Fermented Herb Extract (FKE): An On-farm Study
Katharina Hinz1, Jenny Stracke1, Jule Katrin Schättler2, Birgit Spindler1, Nicole Kemper1
1Institute for Animal Hygiene, Animal Welfare and Farm Animal Behaviour, University of Veterinary Medicine Hannover, Foundation, Bischofsholer Damm 15, D-30173 Hannover, Germany
2Chamber of Agriculture Lower Saxony; Division Agriculture, Mars-La-Tour-Straße 6, D-26121 Oldenburg, Germany
European Poultry Science 83, 2019 https://doi.org/10.1399/eps.2019.266
https://www.european-poultry-science.com/Foot-pad-health-and-growth- performance-in-broiler-chickens-as-affected-by-supplemental-charcoal-and- fermented-herb-extract-FKE-an-on-farm-
study,QUlEPTYxMTk0OTcmTUlEPTE2MTAxNA.html?UID=AE3E7FBC6AA963D93D 9D181C9BBEB69C9AEBAB98B67EC5
Abstract
Foot pad dermatitis (FPD) is considered a very important animal-related welfare indicator in broiler chickens and is mainly caused by wet litter. This field study was conducted to evaluate the effects of fermented herb extract (FKE) enriched charcoal as 0.2 % feed additive on growth performance and FPD status of commercial broiler
Publications 12
chickens (Ross 308). The charcoal was assumed to bind liquids, also in faeces, and reduce the moisture of the bedding compared with that in the control flock. This binding was thought to improve foot pad health and also reduce the adsorption of harmful substances and microorganisms that might influence the chickens’ performance. This on-farm-experiment was conducted in five batches. During that period, the farm was visited weekly over six weeks (days 5, 12, 19, 26, 33, and 40 of life), and data about weights, FPD status, hock burns, soiled cloaca, and soiled feathering were collected.
After emptying the flocks on day 42, pooled litter samples were collected for dry matter content analysis. No significant effect of the treatment was found for the body weight (p > 0.05). Hock burns, soiled cloaca and soiled feathering also revealed no significant differences due to the charcoal supplementation (all p > 0.05). However, scoring of FPD revealed a significant difference between treatment groups (p < 0.01), with feet of birds supplemented with charcoal performing better then control animals. In conclusion, supplementing broiler feed with 0.2% FKE enriched charcoal increased foot pad health but did not affect growth performance, hock burns, soiled cloaca and soiled feathering.
Publications 13
2.2 Effects of Enriched Charcoal as Permanent 0.2 % Feed- Additive in Standard and Low-Protein Diets of Male Fattening Turkeys: An On-Farm Study
Katharina Hinz1, Jenny Stracke1, Jule Katrin Schättler2, Nicole Kemper1, Birgit Spindler1
1Institute for Animal Hygiene, Animal Welfare and Farm Animal Behaviour, University of Veterinary Medicine Hannover, Foundation, Bischofsholer Damm 15, D-30173 Hannover, Germany
2Chamber of Agriculture Lower Saxony; Division Agriculture, Mars-La-Tour-Straße 6, D-26121 Oldenburg, Germany
Animals 9(8): 541, 2019
https://doi.org/10.3390/ani9080541
https://www.mdpi.com/2076-2615/9/8/541#
Abstract:
Wet litter is the most important cause of footpad dermatitis in poultry, this in turn being a highly relevant animal-related welfare indicator. This field study was subdivided into two experiments. In Experiment 1, the standard diet was supplemented by 0.2%
enriched charcoal, being a non-specific absorber and therefore might be promising in reducing faecal moisture. In Experiment 2, the experimental group received a reduced crude protein diet during weeks 6–13, combined with a 0.2% enriched charcoal supplementation. The trials were each conducted with two batches on three farms under on-farm conditions. The animals were observed at 6, 10, 14 and 18 weeks of age to collect data on body weight and different health parameters. The mortality and litter samples were analysed after slaughtering. In Experiment 1, performance and
Publications 14
health were not affected despite higher dry matter content of the litter. In Experiment 2, the weight of birds receiving the protein-reduced diet was decreased significantly throughout the experiment. However, the slaughter weight did not differ. The mortality was reduced by 0.5% in the experimental group. Therefore, it was concluded that 0.2%
of enriched charcoal is not a valuable feed-additive regarding animal health, while temporary protein reduction might have positive effects.
Discussion 15
3. General Discussion
In commercial farming, farmers use a wide variety of feed supplements to improve the performance and health of their animals. Precise information about the effectiveness of individual additives is rare. The use of feed supplements is often based on empirical values and not on scientific results. However, it is important to ascertain the benefits and possible detriments of these substances and evaluate whether their use is reasonable and advisable. The aim of the present study was to analyse the effects of dietary wood charcoal enriched with fermented herb extract as an 0.2% feed additive in broiler chickens and fattening turkey toms on the growth performance and selected health parameters under on-farm conditions. In turkeys, temporary reduction in crude protein content was examined as well.
In this study, body weight in both broiler chickens and turkey toms was not influenced by the enriched wood charcoal supplemented diet. The mortality rate was higher in broiler chickens fed the charcoal supplemented diet. In turkeys, there was no difference between the groups. This contradicts the results of Majewska et al. (2002) and Majewska et al. (2011), who found that growth performance was improved in both species. In these former studies, 0.3 % hardwood charcoal was added to the feed of the birds and higher body weights and lower mortality rates in the treatment groups were found. The contrasting results could be caused by the differences in charcoal quantity and quality, but also by the varying housing conditions. However, apart from their research, most other studies found the growth performance to be only partially improved, many studies finding no effects at all. For example, the investigations carried out by Kutlu and Unsal (1998) and Kutlu et al. (2001), who supplemented the diet of broiler chickens with 2.5 %, 5 % and 10 % oak charcoal, showed that the body weight increased with each dosage in the period of 8 to 28 days of age, but not during the total fattening period from days 8 to 49 of age. In the present study, no interaction effect of age and diet could be found in broiler chickens. In turkeys, in which the experiments started after the rearing period in the sixth week of life, no interaction effect could be detected during the fattening period. It therefore cannot be excluded that the greatest impact is at an early age when gastrointestinal microbial flora is not
Discussion 16
yet fully developed. In broiler chickens, the microflora is stable after two weeks in the small intestine and after six weeks in the caecum (Coloe et al., 1984). In the first study, we discussed that the amount of charcoal might have an influence and therefore a higher percentage of charcoal in the diet could be worth investigating. However, even 10 % dietary charcoal had no influence on the growth performance when considering the total fattening period (Kutlu et al., 2001). What seems to be an important factor for the impact of the coal is its quality. The adsorption characteristics are, among others, dependent on the number and size of the pores, the surface area and cation-exchange capacity (CEC). These parameters vary depending on the basic material and the process of pyrolysis. Therefore, the divergent outcome of the two compared charcoals in the study by Kana et al. (2011) is not surprising. Regrettably, the characteristics of the used charcoals are not specified in the former publications which impedes the comparability. The carbon used in the present study had low cation-exchange capacity in comparison to clay, a high pore volume and surface area, and an alkaline pH-value.
Nonetheless, the ideal properties for its use as feed additive are still unknown.
Another aspect to be discussed is that charcoal is a non-specific absorber, binding a wide spectrum of substances. The presumed beneficial effect comprises the absorption of harmful components of ingesta. On the other hand, charcoal could absorb compounds such as minerals, vitamins and drugs which the birds need. The favourable and adverse effects could cancel each other out. Consequently, the mutual compensation could have caused the non-affected results of the growth performance in most of the previous studies (Sung et al., 2006; Ruttanavut et al., 2009; Yamauchi et al., 2010; Rattanawut, 2014; Wilson et al., 2016).
The animals in the studies cited earlier were mostly kept in individual cages or in groups of up to 16 birds (Kutlu et al., 2001; Yamauchi et al., 2010). Even groups of 100 broiler chickens as was the case in the study by Majewska et al. (2011) have to be considered as a small group compared to the numbers commonly occurring on commercial farms. This factor has a marked impact on the housing conditions and the risk of infections. Moreover, these aforementioned studies were conducted in experimental settings, wherefore the conditions were controlled to a great extent. In
Discussion 17
the present study, the birds were kept on-farm, which results in a higher influence of external factors. Even though it was aimed at standardising conditions such as genetics, management, and provision of food and bedding as far as possible, some parameters could not be influenced. For instance, there are farm-specific differences in management and local conditions, variations in breeders’ age and breeders’ health as well as in the health of the young birds after hatching or rearing. However, these differences are common on-farm. Therefore, the used feed additives should have an impact despite these external influences; otherwise, their application would be of little value.
The second focus of this study was to examine the effect of the enriched charcoal as 0.2 % feed additive on selected health parameters of broiler chickens and turkey toms.
It was hypothesised that dietary charcoal binds liquids in the faeces. Consequently, the litter should remain drier, and contact dermatitis such as foot pad dermatitis, hock burns, and breast buttons should be reduced. To the best of our knowledge, there have been no previous studies on these parameters. In the present study, the application of charcoal resulted in higher dry matter content of the litter. In broiler chickens, the groups with the carbon supplemented diet showed significantly improved foot pad health. Conversely, the foot pad lesions in turkey toms were not affected by the dietary treatment. It has to be borne in mind that the bedding material of both species was different. While the housing of the broiler chickens was littered with pelleted wood and straw, the turkey toms were kept on long stem straw. Due to their various properties regarding water evaporation, they are not equally suitable as bedding material.
Especially non-shredded straw has very a poor absorption capacity which results in increased litter moisture (Benabdeljelil & Ayachi, 1996) and foot pad dermatitis (Berk, 2009; Youssef et al., 2010). Compared to materials such as wood shavings, dried maize silage, straw pellets and rice shells, broiler chickens kept on long stem straw had the poorest foot pad health (Berk, 2009). As litter material is an important factor for litter wetness (Tucker & Walker, 1992), the different materials may explain why charcoal had a beneficial effect on foot pad dermatitis in broiler chickens but not in turkey toms. Furthermore, there are differences in the length of the husbandry period and the housing conditions. Male turkeys are slaughtered after 21 weeks of life, broiler
Discussion 18
chickens are fattened in six weeks. Therefore, turkeys are predisposed to more severe skin lesions, but the longer period also allows the healing of foot pad dermatitis when the litter is drier (Martland, 1985). In turkey husbandry, open poultry housing with passive ventilation systems were used, while in contrast, broiler chickens were kept in solid buildings with forced ventilation which influences the housing climate and the desiccation of the litter. Soiled cloacae and the faeces quality were assessed as a direct indication of diarrhoea, but no effects caused by charcoal were detected. The other scored parameters related to litter moisture such as breast buttons in turkeys, and hock burns and soiled feathering in broiler chickens were not affected by the supplementation of charcoal to the diet in either of the species. The reason could be that these parameters are less sensitive than foot pad dermatitis. Moreover, the broiler chickens on this farm were generally in good health, and with 10.2 % had a low prevalence of foot pad lesions. Other studies observed much higher prevalence rates ranging from more than 30 up to 99.5 % (Xavier et al., 2010; Hashimoto et al., 2011;
de Jong et al., 2012). Due to their comparatively good health, the occurrence of a ceiling effect is plausible so that a further improvement was not achievable. In contrast to that, the prevalence rates of foot pad dermatitis in the turkey toms were high with more than 95 %. However, this high prevalence is frequent in turkey farming (Krautwald-Junghanns et al., 2011; Allain et al., 2013). Despite the drier litter, the charcoal supplementation had no effect either on foot pad dermatitis and breast buttons or on the turkeys’ performance in the present study. Therefore, it can be concluded that 0.2 % enriched charcoal is of little importance in the diet of fattening turkey toms. Here, a higher dosage of charcoal might intensify the potential effects of the carbon. In former studies, concentrations of 1.5 % up to 10 % were tested without finding negative consequences on the growth performance (Kutlu et al., 2001;
Rattanawut, 2014). Thus, a higher percentage of dietary charcoal might be worth investigating.
In turkeys, an additional part of the investigations was to analyse the effects of a temporary crude protein reduced diet (1 %) combined with a 0.2 % supplementation of charcoal. As protein undernutrition results in decreased growth rate (Hulan et al., 1980;
Plavnik & Hurwitz, 1985) and breast muscle weight (Kidd et al., 1997), in the present
Discussion 19
study, the protein reduction was limited to the first and second grower feed phases.
Thus, the economic efficiency was not adversely affected. Even though the body weight of the turkey toms was significantly reduced, the slaughter weight was not impaired. In the 14th week of life, there was a numeric difference between the feeding groups, but no interaction effect between age and diet was detected. After receiving the standard diet for four weeks, the treatment group showed the same weight level as the control group. This phenomenon was depicted earlier by Auckland and Morris (1971) and Plavnik and Hurwitz (1988) in turkeys and by Zubair and Leeson (1996) and Plavnik and Hurwitz (1985) in broiler chickens as well. The authors defined this as compensatory growth which was described as increased growth after a period of undernutrition (Wilson & Osbourn, 1960). The effect of compensatory growth was found in different species such as cattle (Ryan et al., 1993) and fish (Jobling et al., 1994). In this study, the mortality of the turkeys was 0.5 % lower in the group with the protein-reduced diet. This could be explained by the slower growth rate in the early fattening period. High growth rates are suspected to contribute to the sudden death syndrome (Bowes et al., 1988) and to increase the prevalence of lameness in broiler chickens (Kestin et al., 2001), although no data were collected on these in the present study. However, the protein-reduced and charcoal supplemented diet did not influence the prevalence or severity of pododermatitis or breast buttons. Probably, a diet with even lower protein content would have a reinforcing effect. Although the dry matter content of the litter was slightly higher in the treatment group, it was not as high as in the trial with a charcoal supplemented standard diet. A possible cause of this outcome is the altered feed. Due to the fact that the water excretion level is influenced by the potassium or oligosaccharide content of the feed (Youssef et al., 2011a), modifications of dietary composition can result in increased water excretion. Another fact corresponding to that is the faecal quality being worse in the treatment group than in the control during the first half of the fattening period.
However, another litter parameter has to be emphasised. The decreased total nitrogen content in the dry matter indicates that by saving on the amount of dietary protein, the nitrogen emission of animal farming could be reduced. Therefore, this approach might be interesting for further research despite the lack of findings concerning the animal
Discussion 20
health. For analysing the impact of dietary charcoal on the intestinal health, all these parameters may not be conclusive because they reflect the effects indirectly. To research the influence of charcoal on intestinal health, it could be much more interesting to investigate the microbiome of the birds. Even though it was not considered in this examination, analyses of the microbiome are currently being performed and will be published in the near future.
Conclusion 21
4. General Conclusion
In the present study, supplementing the commercial diets of broiler chickens and fattening turkey toms with 0.2 % wood charcoal enriched with fermented herb extract showed no effect on the growth performance of the on-farm birds. In broiler chickens, the dietary charcoal reduced the severity of foot pad dermatitis but had no influence on the pododermatitis of male turkeys. The other parameters (hock burns, soiled feathering and soiled cloacae in the chickens, and breast buttons and soiled cloacae in the turkeys) were not affected by the charcoal supplemented diet. Therefore, it can be concluded that the supplemented 0.2 % enriched wood charcoal per se is not appropriate as a feed additive for improving growth performance and selected health parameters in poultry under on-farm conditions. As in this study no effects of the enriched charcoal were found, it might be reasonably assumed that the decreased mortality rate in turkeys during the second part of the investigation may be caused by the slight crude protein reduction in the first eight weeks of the fattening period.
Moreover, the slaughtering weight was not negatively affected by the temporary protein reduction. Therefore, this might be a promising approach for future research on nitrogen emissions. However, to clarify the impact of the dietary charcoal, further studies should investigate the feeding of protein-reduced diets without charcoal supplementation.
Summary 22
5. General Summary
Katharina Hinz (2019)
“Enriched charcoal as feed additive in the nutrition of commercial broiler chickens and male fattening turkeys kept under on-farm conditions”
In poultry farming, animal welfare is evaluated by animal-related indicators, especially by the prevalence of foot pad dermatitis. Foot pad dermatitis is mainly caused by wet litter and, therefore, it reflects the quality of housing conditions directly on the skin of the birds. Litter moisture is influenced by many factors such as diet, bedding material, housing climate and stocking density. Using feed additives such as charcoal is a widespread practice, although often there exist no valid data about their effectiveness.
Charcoal is a non-specific absorber; hence, it is often used as a household remedy for intoxications and diarrhoea. Animal studies reported that charcoal improves growth performance as well as histological structures of the intestine and is helpful in treating some intestinal infections. However, all these findings were achieved in experimental settings.
The aim of the present study was to analyse the effects of herbal fermentation extract enriched charcoal as 0.2 % feed additive on the growth performance and selected health parameters of broiler chickens (five batches on one farm) and fattening turkey toms (three farms, two batches on each) under on-farm conditions. The charcoal was supposed to absorb toxins in the intestine and liquids in the faeces, which could decrease the litter moisture compared to the control flocks. The reduced litter moisture was expected to improve foot pad health and other contact dermatitis, and the absorption of potentially harmful substances and microorganisms might be beneficial for the growth performance. In the second part, the diet of the turkey toms was additionally protein-reduced for the first half of the fattening period to reduce nitrogen emission without risking economic losses due to impaired growth.
To assess the effects of charcoal on the broiler chickens and turkey toms, representative samples of animals were individually weighed and scored regularly. The
Summary 23
focus was placed on foot pad dermatitis. Furthermore, hock burns, soiled feathering and soiled cloacae were scored in chickens, and breast buttons and soiled cloacae were graded in turkeys. Moreover, pooled samples of the litter were collected, and the dry matter content was analysed, and in turkey litter, the total nitrogen of the dry matter was additionally evaluated.
Neither in broiler chickens nor in turkey toms did the dietary charcoal affect the growth performance. In the turkeys, the combination of charcoal with temporary protein reduction decreased the body weight during the fattening period but did not influence the slaughter weight. In broiler chickens, pododermatitis was significantly reduced (p<0.05) in the groups with charcoal supplementation. The parameters hock burns, feathering and cloacae showed no effect of the diet. In turkey toms, neither foot pad dermatitis nor breast blisters and soiled cloacae differed between the control and the charcoal supplemented standard diet groups. Moreover, none of these parameters were affected by the additional protein-reduced feed. However, as a result of this treatment, the mortality rate was reduced by 0.5 % on average compared to the control group. The dry matter content of the litter was increased in the treatment groups of both species. In turkeys, the total nitrogen was reduced in both variants of the diets compared to the control.
The results of this study show that the supplementation of 0.2 % enriched charcoal cannot improve the growth performance of broiler chickens and male fattening turkeys.
Whereas charcoal reduced the severity of foot pad dermatitis in broiler chickens effectively, there was no effect detected in any observed health parameter of the turkeys. Therefore, it can be concluded that 0.2 % dietary charcoal is not an efficient feed additive in turkey toms but at least partially beneficial in broiler chickens. However, the temporary crude protein reduction did not influence the slaughter weight and reduced the mortality rate, though this might be a promising approach for reducing nitrogen emission in future research.
Zusammenfassung 24
6. Zusammenfassung
Katharina Hinz (2019)
“Enriched charcoal as feed additive in the nutrition of commercial broiler chickens and male fattening turkeys kept under on-farm conditions”
“Aktivierte Pflanzenkohle als Futtermittelzusatz in der Ernährung von kommerziellen Masthühnern und Mastputenhähnen unter Praxisbedingungen“
In der kommerziellen Geflügelhaltung werden zur Bewertung des Tierwohls tierbezogene Indikatoren herangezogen, wobei der wichtigste das Auftreten von Pododermatitis ist. Die Hauptursache von Fußballenentzündungen ist feuchte Einstreu. Dies ist vor allem deswegen interessant, weil sich dadurch die Qualität von Management und Haltungsbedingungen direkt auf der Haut der Vögel widerspiegeln.
Die Einstreufeuchte wird durch viel Faktoren beeinflusst, z. B. durch das Futter, Einstreumaterial, Stallklima und Besatzdichte. Die Verwendung von Futtermittelzusätzen ist eine weit verbreitete Praxis, obwohl es oftmals keine fundierten Daten zur Wirksamkeit gibt. Ein möglicher Futtermittelzusatz ist Pflanzenkohle. Diese ist ein unspezifischer Absorber und wird daher oft als Hausmittel bei Vergiftungen und Durchfall angewendet. Kohle findet auch bei Tieren Anwendung und Studien haben herausgestellt, dass sie die Mastleistung und histologische Strukturen im Darm positiv beeinflussen kann. Außerdem erwies sie sich als hilfreich in der Behandlung einiger Darminfektionen. Diese Ergebnisse wurden allerdings alle nur unter experimentellen Bedingungen erzielt.
Das Ziel der vorliegenden Arbeit war es, die Auswirkungen von aktivierter Pflanzenkohle als 0,2%iger Futtermittelzusatz auf die Mastleistung und ausgewählte Gesundheitsparameter von Masthühnern und Mastputenhähnen unter Praxisbedingungen zu untersuchen. Die mit einem Kräuterextrakt versetzte Pflanzenkohle sollte Toxine im Darm und Flüssigkeiten in den Fäzes aufnehmen, um den Feuchtigkeitsgehalt der Einstreu im Vergleich zur Kontrollgruppe zu reduzieren.
Durch die geringere Feuchte des Mists wurde erwartet, dass Fußballengesundheit
Zusammenfassung 25
verbessert und andere Kontaktdermatitiden ebenfalls reduziert würden. Außerdem könnte die Adsorption von potentiell schädlichen Substanzen und Mikroorganismen die Mastleistung steigern. Im zweiten Teil der Untersuchungen wurde bei Puten in der ersten Masthälfte zusätzlich zur Kohle ein proteinreduziertes Futter eingesetzt, um die Stickstoff-Emission zu senken ohne wirtschaftliche Einbußen durch beeinträchtigtes Wachstum zu riskieren.
Um die Effekte der Kohle zu messen, wurden regelmäßig Stichproben der Tiere individuell gewogen und Gesundheitsparameter bonitiert. Bei den Hühnern wurden Pododermatitis, Hock Burns, Gefiederverschmutzung und Kloakenverschmutzung beurteilt, bei den Putenhähnen Pododermatitis, nekrotische Brustblasen und Kloakenverschmutzung. Weiterhin wurden Pool-Proben von der Einstreu genommen und der Trockenmassegehalt bestimmt, bei den Puten kam zusätzlich noch die Messung des Gesamtstickstoffs in der Trockenmasse hinzu.
Weder bei den Masthühnern noch bei den Puten beeinflusste die zugesetzte Pflanzenkohle die Mastleistung. In Kombination mit dem proteinreduzierten Futter zeigten die Puten ein signifikant geringeres Gewicht während der Mast (P<0,05), aber das Schlachtgewicht war nicht reduziert. Bei den Masthühnern hatte die Kohle einen signifikanten positiven Effekt auf die Fußballengesundheit, wohingegen keine Auswirkungen auf Hock Burns, Gefieder- und Kloakenverschmutzung feststellbar waren. Bei den Puten konnte weder mit Standardfutter noch mit der proteinreduzierten Variante ein Unterschied zwischen den Gruppen hinsichtlich der untersuchten Parameter gefunden werden. Allerdings war die Mortalität in der proteinreduzierten Fütterung im Durchschnitt um 0,5% niedriger als in der Kontrolle. In allen Untersuchungen war der Trockenmassegehalt im Mist der Kohlegruppen höher als in den Kontrollen und der Gesamtstickstoffgehalt bei den Puten war in diesen Gruppen reduziert.
Die Ergebnisse dieser Arbeit zeigen, dass der Zusatz von 0,2% aktivierter Pflanzenkohle die Mastleistung von Masthühnern und Putenhähnen nicht verbessern kann. Während Kohle den Schweregrade der Pododermatitis von Masthühnern effektiv reduzieren konnte, konnte bei Puten auf keinen der untersuchten Parameter
Zusammenfassung 26
ein Effekt beobachtet werden. Daher kann geschlussfolgert werden, dass 0,2%
Pflanzenkohle kein nutzbringender Futterzusatz bei Puten ist, aber bei Masthühnern zumindest die Fußballengesundheit fördern könnte. Die zeitlich begrenzte Proteinreduzierung hatte keine negativen Auswirkungen auf das Schlachtgewicht der Puten und senkte die Mortalität. Daher könnte sie einen vielversprechenden Ansatz zur Verringerung der Stickstoffemission für zukünftige Forschung darstellen.
List of publications 27
7. List of publications
In addition to the papers included, the following publications were published in conjunction with this thesis:
HINZ, K., STRACKE, J., SPINDLER, B., KEMPER, N. (2018):
Einfluss von Pflanzenkohle als Zusatz zum Futter von Masthühnern auf Gesundheits- und Leistungsparameter unter Praxisbedingungen. In: Tagungsband der Vortragstagung der DGfZ und GfT, Bonn, 12.-13.09.2018, D6
HINZ, K., STRACKE, J., KEMPER, N., SPINDLER, B. (2019):
Black food for fowl – Effects of enriched charcoal in a temporary crude protein reduced diet on male turkeys fattened under on-farm conditions. In: Proceedings ICPD 2019, 17th International conference on production diseases in farm animals, 27.-29.06.2019, Bern, Switzerland, 55
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Acknowledgements
9. Acknowledgements
Firstly, I express my sincere gratitude to Prof. Nicole Kemper for her continuous support, reliable supervision and stimulating feedback throughout my research.
I would like to thank Dr. Birgit Spindler for her individual guidance, genuine sympathy and encouraging discussions.
My sincere thanks also go to Dr. Jenny Stracke for her constructive conversations, endless patience and mental support. I could not have imagined better mentoring for scientific work.
Furthermore, I would like to thank my colleagues at the Institute for Animal Hygiene, Animal Welfare and Farm Animal Behaviour for the good working atmosphere, a lot of fun, constant assistance and for always being willing to listen to each others concerns.
In addition, there are my friends, who were of great support in difficult situations, as well as providing welcoming distraction to rest my mind outside of my research.
Finally, I would like to thank my beloved family: my parents and my brother for their wise advice and sympathetic ears and for always being there for me.
Versicherung an Eides statt
Hiermit versichere ich an Eides statt, dass ich die Dissertation mit dem Titel „Enriched charcoal as feed additive in the nutrition of commercial broiler chickens and male fattening turkeys kept under on-farm conditions” selbstständig verfasst habe.
Bei der Anfertigung wurden keine anderen als die aufgeführten Hilfsmittel eingesetzt.
Ich habe keine entgeltliche Hilfe von Vermittlungs- bzw. Beratungsdiensten (Promotionsberater oder anderer Personen) in Anspruch genommen. Niemand hat von mir unmittelbar oder mittelbar entgeltliche Leistungen für Arbeiten erhalten, die im Zusammenhang mit dem Inhalt der vorgelegten Dissertation stehen.
Ich habe die Dissertation an folgender Institution angefertigt: Institut für Tierhygiene, Tierschutz und Nutztierethologie, Stiftung Tierärztliche Hochschule Hannover Die Dissertation wurde bisher nicht für eine Prüfung oder Promotion oder für einen ähnlichen Zweck zur Beurteilung eingereicht.
Ich erkläre, über die Bedeutung der Versicherung an Eides statt informiert worden zu sein. Mir wurde der Inhalt der folgenden Vorschriften des Strafgesetzbuches bekannt gegeben: § 156 StGb - Falsche Versicherung an Eides statt.
