Jacqueline Jacob and Anthony Pescatore The term guineafowl is the common name for six species of gallinaceous birds of the family Numididae. The six species of guineafowl include the white‐breasted, helmeted, black, plumed, crested and vulturine. Guineafowl were first discovered in the Guinea coast of West Africa, from which the name derives. Guineafowl are endemic to Africa where temperature and rainfall appear to have played important roles in their ecology and evolution. The domesticated strains were developed from the helmeted guineafowl (Numida meleagris). Guineafowl are said to have been domesticated by the ancient Egyptians about 1475 BCE, the Greeks about 400 BCE, and the Romans by 72 CE. These strains later died out in Europe. The ancestors of the domesticated guineafowl we know today were introduced into Europe during the late fifteenth century. From there, they spread to the rest of the world, including North America. As in the past, guineafowl are valued for their taste and nutritional value [1]. Guineafowl come in color varieties rather than breeds. The original color is referred to as pearl which has a purplish‐gray plumage that is “pearled” with white spots on the entire body (Figure 17.1). Breeding has led to the development of at least 25 different colors, but not all colors are recognized by official standards. The American Poultry Association recognizes three varieties: lavender, pearl, and white. The Australian guineafowl standards set by the Victorian Poultry Fanciers Association include those three plus the cinnamon and pied varieties. Landrace strains are those that have been developed by local traditional agricultural methods and in different countries. Industrial strains have been developed in France, Belgium, and Italy and are exported worldwide. The birds are easily recognized by their distinctive head features (Figure 17.2). In most developing countries, poultry production is based primarily on scavenging systems which are a traditional component of smallholder farmers. Poultry production is the most common economic activity practiced by 80% of the resource‐poor households across southern Africa [2]. For most households, guineafowl complement village chickens by utilizing spaces and feeds that are not accessible to the chickens. Compared to scavenging chickens, scavenging guineafowl produce more eggs. Guineafowl is a poultry species whose production is increasing worldwide. Commercial production of guineafowl is similar to that of broiler chickens, with the species raised for meat since the consumption of guineafowl eggs is not very popular [3]. In developed countries, most guineafowl meat is served in restaurants. The pearl guineafowl is the dominant variety raised commercially for meat production because they grow twice as fast as nonselected guineafowl, and the carcass is leaner than that of the French industrial strain [4]. Figure 17.1 Pearl guineafowl. Source: Photo courtesy of Dr Jacqueline Jacob, University of Kentucky. Figure 17.2 Anatomical nomenclature of the head of a guineafowl. Source: Photo courtesy of Dr Jacqueline Jacob, University of Kentucky. In the United States and Europe, guineafowl meat is seen as an alternative to chicken and is preferred for its gamey flavor [5]. In addition, guineafowl meat is higher in protein and lower in fat compared to broiler chickens [6]. With increasing consumer interest in healthful products and animal‐friendly production systems, guineafowl may fill a niche market for alternative poultry species [7]. Guineafowl have a small skeletal frame, and their carcass yield a large amount of meat [8]. Guineafowl breast meat contains more protein and less fat and is darker in color, redder, and less yellow than chicken breast meat [9]. As guinea fowl age, the meat color becomes darker, redder, and yellower. Shear force increases with age, while cooking loss decreases. Different cuts of guineafowl vary in their nutrient content, which in turn is affected to varying degrees by the cooking method used [10]. As with chickens, the thigh meat has a higher fat content than the breast. The open‐roasting method has been shown to result in higher protein content in the breast compared to cooking in foil wrap. Moisture content of thigh and drumstick was not affected by cooking method, while breast meat retained the most moisture when open‐roasted. Cooking loss is higher in guineafowl than chickens. The higher meat yield of guineafowl suggests that they can be produced as an additional or alternative protein source to the traditional chicken [9]. An American consumer preference study evaluated acceptance of guineafowl as a poultry meat [11]. The study recruited 40 families which prepared supplied guineafowl carcasses. Participants selected a cooking method of their choice, with most choosing either baking or roasting. After consuming the prepared product, they evaluated the product. They reported the meat as being moderate to mild in flavor, tender to very tender, and juicy to slightly juicy. No participants said they disliked the product. Most said that the guineafowl was at least equal to chicken and they would purchase guineafowl if they were available at an economical price. Guineafowl are characterized by their harsh cry and are easily agitated. Research has shown that guineafowl keets display acoustic imprinting [12]. Apparently seeing the imprinted object is not necessary as long as it can be heard. A recording of the sound is sufficient. Guineafowl are less docile than other poultry species [13]. Although a very sociable species, guineafowl do not like confinement [13, 14]. In backyard flocks, guineafowl can be housed with other poultry species since they tend to keep to themselves and occupy different parts of the poultry house. However, aggression between guineafowl and roosters has been reported and is a concern (Figure 17.3). Many of the behaviors characteristic of wild guineafowl are displayed in domesticated birds. The helmeted guineafowl is a common component of the African landscape. Its wide distribution is partly due to its ability to adapt to varying ecological conditions. Habitats for wild guineafowl include open forests, savannas, and grasslands. Analysis of the crop contents of hunted guineafowl revealed diets consisting of grass seeds, insects, Cyperus bulbs, fruits of flowering plants, leaves, and other vegetable matter [15]. As with other poultry species, guineafowl consume pebbles to help with the grinding of feed in the gizzard. With the encroachment of humans into the natural habitat of guineafowl, small maize fields, waste grain, and fallow lands now form important components of their range [16]. Like most poultry species, guineafowl like to dust bathe and in the wild will do so in the sandy soils along riverbeds [17]. Wild guineafowl nest under the canopies of bushes and utilize the trees as roosting sites. In the wild, guineafowl stay in flocks of 7–10 [18]. They appear to establish a pecking order among the males, although the frequency of agonistic actions within the flock is low. The highest‐ranking male dictates the movement of the flock, including which direction to travel to forage. Adult females routinely stay between the dominant male and the juveniles to minimize victimization. During the breeding season, the dominant male guineafowl will leave temporarily with his favored female to mate. The second highest male then takes center stage and the rest of the flock cluster around him to maintain cohesion in the flock. Most adults assist with the brooding of the chicks of the highest‐ranking male [18]. Figure 17.3 Fighting between guineafowl and a rooster. Source: Photo courtesy of Dr Jacqueline Jacob, University of Kentucky. Guineafowl are said to be resistant to many poultry diseases [19], but they can still be spreaders of many diseases so a good biosecurity program is essential. Globally, there is concern about the introduction of the Asian‐origin, highly pathogenic avian influenza subtype H5N1 and its effects on the local commercial poultry industry. In 1999, an epidemic of low‐pathogenicity H5N1 avian influenza (LPAI) occurred in intensively reared poultry in north‐eastern Italy. Many poultry flocks were affected, including guineafowl. After the LPAI virus circulated through the flocks, highly‐pathogenic (HPAI) viruses emerged. HPAI caused similar mortality rates in chickens, turkeys, and guineafowl. Newcastle disease is a contagious disease of poultry with a wide range of avian hosts worldwide. Guineafowl are susceptible to Newcastle disease (ND) and natural infections have been reported in various countries. In a natural outbreak of Newcastle disease in Nigeria, the affected guineafowl showed paralysis of the legs and wings, coughing, sneezing, white diarrhea, and complete cessation of egg production [20]. Newcastle disease viruses have also been isolated from apparently healthy guineafowl [21, 22]. In many developing countries, control of Newcastle disease is by vaccination, but this applies largely to commercial poultry. Unfortunately, the large population of rural poultry, including guineafowl, remains largely unvaccinated and susceptible to Newcastle disease infection, with continuous shedding of the virus. Domesticated guineafowl should be vaccinated against ND to reduce shedding and spread of virulent ND [22]. It appears guineafowl may not be susceptible to infectious bronchitis virus [23]. Guineafowl have been shown to be naturally infected with mycoplasmas, including M. synoviae (MS) and M. gallisepticum (MG) [24]. Guineafowl naturally infected with MS showed clinical signs of synovitis. Experimental infection with the MS isolated from the natural infection showed clear pathogenicity for guineafowl, and to a lesser degree for chickens. In guineafowl, the strain was more likely to result in synovitis and amyloidosis when inoculated by the intravenous route and to produce sinusitis after intrasinusal inoculation. For decades, guineafowl production in France has been affected by fulminating enteritis of unknown origin [25]. Fulminating disease of guineafowl is an acute enteritis that is characterized by intense prostration and a very high death rate. An infection can lead to almost complete destruction of a flock. Lesions are generally limited to severe enteritis, although some guineafowl show pancreatic degeneration. It is suspected to be of viral origin. Liais et al. used metagenomics and identified a novel avian gamma‐coronavirus associated with the disease that is distantly related to turkey coronaviruses [25]. Guineafowl can be infested with the same external parasites that infest most poultry species, including mites, fleas, lice, and ticks [26]. Wild guineafowl can be infested with 7–13 species of parasites on any one bird. External parasite infestations in intensively reared guineafowl can led to feather damage, reduced feed intake, and even death. In Africa, scavenging guineafowl flocks host more species of external parasites than those raised under intensive management, but free‐ranging guineafowl appear to be not as badly affected by the infestations. This may be due to behavior activities of free‐ranging guineafowl which are often not seen in those raised intensively. This includes communal pecking of each other to remove foreign bodies, ritual sexual dancing behavior, play, and sand bathing. Each of these activities could dislodge ectoparasites and thus reduce the parasite buildup that resulted in the clinical signs noted in the guineafowl raised intensively [26]. The most important intestinal parasites are coccidiosis (Eimeria sp.), roundworms (Ascaridia galli), cecal worms (Heterakis sp.), and hairworms or threadworms (Capillaria caudiflata) [27]. Common hosts of cecal worms (Heterakis gallinarum) include the chicken, turkey, guineafowl, ring‐necked pheasant, partridge, and many other gallinaceous birds [28]. Heterakis gallinarum, however, thrives best in the guineafowl and ring‐necked pheasant. The chicken is the third most suitable host. The parasite is unable to reproduce sufficiently in other hosts, including the turkey, to maintain populations. Heterakis gallinarum has a direct life cycle and does not require an intermediate host to complete development. The parasite itself typically only causes mild pathology and does not significantly affect bird performance. However, the ovum of H. gallinarum serves as the vector for the protozoal parasite Histomonas meleagridis which causes histomoniasis in poultry [28]. Treating and preventing H. gallinarum infections is complicated by the low efficacy of anthelmintics for eradicating the worm from infected birds and because of the low efficacy of disinfectants for destroying the H. gallinarum ova on contaminated farms. A natural outbreak of toxoplasmosis was reported in a backyard flock of guineafowl in northern Mississippi [29]. The flock was infected with Toxoplasma gondii which is a coccidian parasite that can infect many species of warm‐blooded animals, including birds. It can also infect some cold‐blooded animals. The life cycle is indirect and requires both definitive and intermediate hosts. Both wild and domestic cats are the only definitive hosts and at least 141 different species can serve as intermediate hosts. Natural outbreaks in chickens and turkeys have only been sporadically reported, although infections have been reported to occur naturally in chickens, turkeys, ducks, and many wild birds. The infected guineafowl in Mississippi exhibited lethargy prior to death. On necropsy, there were no gross lesions, but intralesional protozoan cysts were observed microscopically. The diagnosis of toxoplasmosis was confirmed with immunohistochemistry and PCR [29]. A similar outbreak occurred in a mixed backyard poultry flock in Brazil [30]. Both chickens and guineafowl were affected. Clinicals signs were lethargy, anorexia, and neurologic signs over a course of 24–72 hours. Of the 22 birds showing clinical signs, 15 died. There were no gross lesions on necropsy, but histopathologic findings included inflammatory infiltrate of macrophages, lymphocytes, and plasma cells. There was necrosis in several tissues associated with intralesional Toxoplasma gondii. Immunohistochemistry for T. gondii was positive. Although the anatomy and physiology of guineafowl are similar to those of chickens, there are some differences in digestive tract morphology that could cause different drug absorptions. The doses of drugs used are often extrapolated from the amount used for chickens or other poultry species. When guineafowl are raised in confinement, bacterial infections such as colibacillosis, mycoplasmosis, or fowl cholera may occur, and antibiotic treatment may be necessary. The pharmacokinetics in quail and guineafowl are similar but show some differences from pheasants [31]. There are limited choices for antibiotics when raising guineafowl and limited information on their use. As an example, for the antibiotic danofloxacin, there is information on pharmacokinetics for chickens, turkeys, and ducks. Danofloxacin, a synthetic fluoroquinolone that is not approved for poultry in the US, is an antibacterial agent that exhibits bactericidal activity against numerous Gram‐positive and some Gram‐negative bacteria, mycoplasmas, and intracellular pathogens such as Brucella and Chlamydia species [31]. According to the data for these poultry species, danofloxacin penetrates the tissues. Tissue concentrations are higher and persist longer compared to blood. Danofloxacin is eliminated mainly unchanged and relatively slowly. The oral bioavailability for these species is high without significant interspecies differences [31]. For pheasants, danofloxacin showed lower distribution and clearance values and longer half‐life than other galliform species. This resulted in a longer presence of the drug in the organism and high area under the curve (AUC) values. The opposite was seen in guineafowl that demonstrated a relatively short persistence of danofloxacin. While 10 mg/kg bodyweight was effective for Japanese quail and pheasants, the authors recommended a higher therapeutic dose for efficacy in guineafowl [31]. Flubendazole is not approved for use in the US but it is used in many other parts of the world, as reflected in corresponding research. When used as prescribed for gamebirds, flubendazole is very active against gastrointestinal roundworms, gapeworms, and tapeworms in guineafowl [32]. Residues of flubendazole and its major metabolites were detected in breast muscle, thigh muscle, and liver of guineafowl treated at 56 or 86 mg/kg bodyweight for 7 successive days. Maximum residue limits (MRL) are based on the sum of the parent flubendazole molecule and its hydrolyzed metabolites. Based on the MRLs established by the European Union for other poultry species, a minimum 3‐day withdrawal period prior to slaughter is recommended [32]. After 3 days, the residues were very low and far below the established safe MRL. However, after an 8‐day withdrawal period, flubendazole‐derived residues were still found in both muscle tissues and liver. The levels of residues in the breast and thigh meat were comparable. Ten hours after guineafowl were treated with a subcutaneous injection of a commercial ivermectin product at 0.14 mg/kg body weight, fecal droppings contained both adult and larval stages of the roundworm A. galli, the cecal worm Heterakis gallinarum, the roundworm Subulura suctoria, and fragments of the tapeworm Raillietina spp. Drug efficacy was rated as 100% [33]. It is important to remember, however, that ivermectin is not an approved drug for poultry in the US and its use would be off‐label and require a veterinarian’s prescription. Probiotics are live microbial feed supplements given to promote the growth and health of the animal. This is achieved by minimizing nonessential and pathogenic microorganisms from the recipient’s digestive tract. The microbial profiles of guineafowl and chickens are sufficiently different that the design of effective probiotics for guineafowl would be different [34]. One of the main differences observed was the presence of Verrucomicrobia (mucin‐degrading bacteria) and Lentisphaerae (bacteria closely related to Chlamydiae and Verrucomicrobia) in the guineafowl digestive tract that were not present in the chicken. Guineafowl, like their chicken counterparts, have been shown to be reservoirs of antibiotic‐resistant Salmonella, Campylobacter jejuni, Camplyobacter lari, Escherichia coli, and Klebsiella spp [35]. There is the potential, therefore, for these antibiotic‐resistant pathogens to be transferred to humans through contaminated guineafowl products. This reinforces the need for more prudent use of antibiotics by poultry producers, and continued development of methods to reduce the risk of foodborne pathogens is critical. Although surgery is not typically performed on commercial poultry, situations may arise that require the use of anesthesia. This could be the case if surgery is needed, or a broken bone needs to be reset. Isoflurane inhalation anesthesia is typically used for most avian species, but its use may not be feasible in the field. Injectable anesthetics are used in animals, such as birds, in which venous access is difficult [36]. Such anesthetics have the benefit of rapid administration, low cost, and minimal equipment requirements. Ketamine can be administered intramuscularly or intravenously but its use can result in poor muscle relaxation, muscle tremors, myotonic contractions, opisthotonos (spasm of the muscles causing backward arching of the head, neck, and spine), and a rough recovery. To counter these problems, ketamine is rarely used alone but instead is paired with another drug. Ketamine‐xylazine combinations have been evaluated in several avian species and have been associated with increased blood pressure, decreased heart rate, and hypoxemia. Intermuscular administration of midazolam improved the anesthetic quality of ketamine and xylazine in guineafowl without adversely affecting safety. The midazolam may improve the quality of anesthesia induced by a ketamine‐xylazine combination in guineafowl and also reduce the dosages required [36]. The reproductive organs of vertebrates typically arise as bilateral primordia and this symmetry usually persists into adulthood. In most avian species, however, there is a failure of one ovary and its corresponding oviduct to develop. The result is normally the presence of the left ovary and oviduct reaching functional development in the adult. This is the case with guineafowl, as with most poultry species [37]. The presence of a right oviduct has been reported in some poultry species, including guineafowl, but it is rare. Typically, if there is a right oviduct, it is underdeveloped with no opening into the cloaca. There is also no corresponding ovary [37]. As with other avian species, guineafowl males have paired testes and highly convoluted vas deferens. The testes and vas deferens are not discernible until about 4 weeks of age [38]. Puberty is said to occur at 12 weeks of age, with sexual maturity around 16–20 weeks. There will, of course, be some variability between varieties and strains in the timing of sexual development [39]. The ovary and oviduct of guineafowl were discernible and measurable at hatching [38]. Sexual maturity in guinea hens appears to occur around 27–28 weeks of age with the onset of egg production, although there are reports of egg production starting as early as 21 weeks of age [38]. Higher oviduct and ovary weights have been reported for guinea hens kept on range versus those on deep litter or in battery cages [40]. This may be an indication of accelerated rate of reproductive development on range. The hens on free range also had higher liver weights which corresponded to follicle recruitment. The liver is the main source of egg proteins and yolk materials. Compared to the domestic chicken, guineafowl eggs are smaller, but eggs of domestic guineafowl are larger and heavier than eggs of their wild counterparts [41]. Guineafowl eggs are typically yellow to brown in color with varied mottling [41]. Guineafowl eggs have a greater shell thickness than most other birds. Eggshells represent 14% of the egg weight in guineafowl and only 10% in the chicken [42]. This increased eggshell mass is related to differences in the timing of eggshell deposition. The rapid phase of calcium carbonate deposition is initiated about 3 hours earlier in the guineafowl [43]. The developing egg spends about 15.4 hours in the shell gland of guineafowl, compared to 13.3 hours in chickens. The rate of shell deposition, however, is similar in both species at about 0.37 g/h. The longer duration of shell deposition in the guineafowl results in greater eggshell mass. The increased time spent in the shell gland for guineafowl does not modify the interval between ovipositions [43]. The mean interval between egg laying is 24 hours for both species. Ovulation occurs in guineafowl about 15 minutes after the previous egg is laid. This is similar to that of chickens. In guineafowl, the ovum arrives in the shell gland in less than 4 hours. The time spent in the magnum for albumen deposition is shorter in guineafowl, which may be the reason that their eggs have smaller amounts of albumen compared to chickens [43]. Eggshell color appears to influence eggshell thickness [44]. Although eggshells are thicker in guineafowl, shell thickness does not appear to affect hatching rates [45]. Eggshell thickness appeared to influence weight loss during incubation but had no effect on hatchability [44]. The higher shell thickness in guineafowl eggs is compensated for by a greater density of pores for gas exchange [41]. The area density of pores decreased from the blunt to the pointed end of the egg. Egg fertility, hatchability, and keet survival rates have been found to be significantly higher in free‐living flocks of guineafowl compared to their domesticated counterparts. Low egg fertility appears to be a key limiting factor in the reproductive success of guineafowl kept in semi‐confinement [14]. Fertility and hatchability rates are considerably lower in guineafowl compared with other poultry species. Fertility levels of 60% have been reported for flocks of guineafowl breeders. This may be due to sexing difficulties, the narrow sex ratio required, and the seasonality of breeding [46, 47]. Although guineafowl are monogamous in the wild, a sex ratio of one male for every four females has been shown to give relatively good fertility [27]. Hatchability is a complex, age‐dependent trait involving both genetic and environmental factors arising from multiple sources [48]. Both sire and dam genetic components are important for overall hatchability. Both the paternal and maternal genetic effects have been shown to vary with the age of the flock [48]. Hatchability of guineafowl eggs has been found to vary among the different varieties, so a genetic component is definitely involved [49, 50]. Selection for lower dead‐in‐germ and dead‐in‐shell phenotypic traits can improve overall fertility and hatchability of guineafowl eggs [49].
17
Guineafowl
17.1 General Behavior and Preferred Habitat
17.2 Health Considerations
17.2.1 Infectious Diseases
17.2.2 External Parasites
17.2.3 Internal Parasites
17.3 Pharmacology Considerations
17.3.1 Probiotics
17.3.2 Anesthetic Compounds
17.4 Reproduction
17.4.1 Anatomy
17.4.2 Reproductive Performance
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