This study is the first attempt to characterize the Tanzanian indigenous goats sampled from all major agro-ecological zones where they are raised and therefore representing all the presumed goat populations in the country. Previous efforts to characterize the indigenous goats in Tanzania have been concentrating on few populations or agro-ecological zones. For a sustainable breeding program, knowledge on purpose of keeping goats is essential (Van Arendonk 2011) because such knowledge is important in defining breeding goals and important features which affect motivation and profitability of long-term breeding programs (Jaitner et al., 2001). Results of this study revealed that goats in all the study areas are multi-functional and that financial functions were the most important in agreement with what was stated in earlier studies from other places in Africa (e.g. Nziku et al., 2016; Dossa et al., 2015; Berhanu et al., 2012). Farmers pay more attention on direct economic impact of the goats rather than their socio-cultural values. This was observed previously in Tanzania and was attributed to availability of markets and cultural changes as a result of modernization of rural communities (Nguluma et al 2016). Milk production was not given emphasis as a production objective of the farmers with exception of Pare goat keepers and this can be attributed to cultural preferences for milk from cows since they co-exist with goats and lack of awareness of nutritional advantages of goat milk. Besides producing animal products including meat and milk, goats also provide manure to maintain soil fertility in mixed crop-livestock and agro-pastoral production systems and have socio-cultural roles to play. The purposes of keeping goats of the farmers have direct implication on their breeding goals which consequently affect their breeding strategies, therefore need to be given consideration in designing and running improvement and conservation programs. Integration with global market chains and abandoning of traditional livestock production systems results in shifting of the breeding goals to focus mainly on economic importance of the livestock. This has a consequence on conservation and continued existence of the valuable animal genetic resources including indigenous goats (FAO, 2005).
General goat husbandry practices
Management aspects including feeding, watering and housing are determined by the production system which is influenced by the agro-ecological conditions of the particular area. Majority of the indigenous goats in Tanzania are raised under traditional extensive production system which is characterized by seasonal shortage of feeds and water. Additionally, majority of indigenous goat keepers are resource poor farmers who reside in marginal rural areas with limited supply of inputs where indigenous animals are adapted and therefore predominant. Under such production conditions only the observed management practices of free grazing with minimal supplementation using locally available feed resources would be feasible. The findings in this study are consistent with study by Chenyambuga and Lekule, (2004) who reported heavy reliance upon natural pastures available in communal grazing lands for feeding goats with little supplementary feeding using maize bran, Sorghum and maize stovers during the dry season after crop harvest.
It can be noted that in areas like Mtwara, Pwani, Tanga, Rukwa and Songwe where mixed crop livestock is the dominant production system, the proportion of farmers who practiced tethering along with free grazing was relatively higher. This was due to shortage of grazing lands especially during wet season when most of the land is taken for growing crops leaving no or little land available for heading and free grazing. Also, it is common during the rainy season for most of the family members to be working on their farm plots and therefore farmers with few animals tether their animals close to their farm plots or their homesteads or leave them indoors and bring them feed when returning from field work.
The observed housing systems across the study areas do not offer protection of animals against predation, theft, weather extremes which could lead to low productivity of the animals. Poor housing of animals has been observed in many smallholder systems in the tropics (Gwaze et al, 2009) and is attributed to lack of knowledge and financial resources of the farmers (Shumba, 1993). Therefore, awareness creation among goat farmers on the importance of improved housing in the performance of goats is important. Low production potential which is usually associated with indigenous goats in the tropics is confounded with low standard of management under which the goats are normally kept (Mpofu, 2002). Therefore in order for indigenous goats in Tanzania to perform to the expectation and requirement of the farmers, any genetic improvement strategies must be accompanied with improvement in the management of the animals ((Philipsson et al. 2006).
Controlled mating is one of the best livestock breeding management practice for improvement of animal productivity to be achieved. Controlled mating is important for genetic improvement as it enables farmers to avoid indiscriminate crossbreeding and inbreeding. Also controlled mating enables farmers to plan for their animals to kid at a time when there is sufficient amount of feeds typically after the rain season. Low level of mating control is caused by several factors including poor land tenure system in which individual land ownership is not encouraged and communal grazing and sharing of watering points is common; typical of extensive production system which is the most predominant in Tanzania. Castration, though not very common in most parts, was the most widely used method among the farmers who reported to practice controlled mating. Apart from controlled mating, improving the quality of meat through fattening and reducing bad smell from bucks to get better price in markets was another motivation for castration. Separation of bucks could work better in controlling mating but under small scale farming systems this could be hard and expensive to have few separate groups of bucks. Considering the low practice of castration and culling against old animals especially bucks, use of breeding bucks from within the flock as observed among the interviewed farmers represents a high risk of inbreeding of which they were probably not aware.
Health management and disease control
In order to develop sustainable strategies for control of small ruminant diseases, there is a need to determine the most important diseases affecting the animals in different areas (Shija et al 2014). The major goat diseases of helminthosis, CPPP and PPR reported by the farmers across the study areas have been mentioned previously by other researchers (Chenyambuga and Lekule, 2014; Nguluma et al, 2020; Onditi et al, 2007; Mbyuzi et al, 2015; Shija et al, 2014). Nguluma et al. (2020) reported high incidences of helminthosis and CCPP among the Maasai goats and associated the prevalence to management systems of the farmers. High contamination of pastures with eggs or larvae lead to high incidences of helminthosis and overcrowding in watering points and grazing and poor housing expose animals to stressful weather conditions and increase the chances for CCPP to spread between and within herds. High cases of CCPP and PPR have been reported in southern regions of Tanzania, native to Newala and Mtwara goats and the increase in cases has been associated with purchase of animals from outside to replenish stocks following increased slaughter of goats during the time of festivals commonly January to February of every year. The practice brings in animals from other goat rearing zones which are already infected and endemic for CCPP and PPR. Most of the disease challenges reported by the farmers result from poor management, including poor housing, inadequate feeding and feeding systems, irregular disease control strategies, thus improvement in management will likely alleviate the problem. In addition to providing knowledge and awareness to farmers on the importance of management on disease occurrence, knowledge on importance of adhering to proper veterinary drug use will limit recurrence of diseases and cut drug resistance that might arise from their improper use. In a previous study in one of the study sites, Nguluma et al al. (2020) noted excessive use of veterinary drugs from unauthorized dealers and treatment of animals by farmers without consulting authorized veterinary officers despite the availability and easy access to veterinary services from qualified veterinary practitioners.
Constraints to goat production
Goat production in communal areas is faced with many constraints which may differ with areas, countries, regions or geographical locations (Kosgey 2004). The major constraints facing goat farmers in the study areas differed but the major ones were similar across the study areas. Similar to the observation in this study, high prevalence of diseases and parasites, feed and water shortage as well as drought have been reported by other researchers in Tanzania (Nguluma et al, 2020; and elsewhere in Africa as most influencing constraints to goat production (Raghuvansi et al. 2007; Ben Salem and Smith, 2008; Gatew, 2004). Contrary to the findings in this study, Chenyambuga and Lekule (2014) reported animal health problems not to be the major concern of the goat keepers in central Tanzania attributing this to tolerance of indigenous goats to endemic diseases.
Variation in quantitative traits among the Tanzanian indigenous goat populations
Description of the animal phenotypic features in terms of body measurements is important in making taxonomic, behavioural and ecological comparisons within and between animal populations and explaining intraspecific variation in morphology over broad environmental gradients (Mittelbach et al., 2007). Body weight is a trait of economic importance in livestock production and one of the most preferred traits reflecting farmers’ main production objectives of income generation and meat production. The range of 24 kg to 32 kg of body weight of indigenous goats in the study areas were above the range of 20 to 25 kg that has been reported previously for other mature SEA goats in traditional farming (NEI 1999). Similar to the findings of this study, Madubi et al. (2000) reported body weight of 31.8, 29.2 and 23.9 kg for Gogo, Newala and Ujiji goats while Nguluma et al. (2016) found Pare and Sukuma to weigh 29.8 and 22.3 kg respectively. Body weight of Sukuma and Ujiji which were the smallest of the goat populations in the present study, were above the average weight of 14.51kg reported for Dwarf goats of West Africa (Rotimi et al, 2017). However, the body weights of the indigenous goats in the study areas are lower than that of Blended goats, a famous composite breed kept for meat in Tanzania, which was reported to weigh above 40kg (Das and Sendalo, 1991).
Variations observed in body weight and body dimension among the indigenous goat populations may be due to isolation-by-distance, historical and geological factors, physical barriers and ecological factors through morphological adaptation to local conditions (Mekuriaw et al, 2016). The indigenous goat populations studied are found in different geographical areas with varying ecological characteristics. Ecological variations influence the body measurements of the goats through differences in feed and water availability and environmental temperature. Based on wither height measurements; Devendra and Burns (1983) classified goats as large if they were above 65 cm, small to medium if they measured between 51 and 65 cm and dwarf for those with wither height below 50 cm. Based on this classification, indigenous goats in Tanzania can be categorized as small to medium sized. Phenotypic features are influenced by the environment as well as genetic constitution of the animal; therefore, it is difficult to conclusively associate body measurements to any genetic background or the ecological variations of study areas. Traits like height at withers and body length have been reported to be more genetically determined while heart girth is more subject to environmental influences (Searle et al., 1989; Hall, 1991). The relatively high coefficients of variation (CV) obtained in this study for quantitative traits indicate absence of selection, or influence of the environment on the body parts. Studies of variation of the goats at molecular level may reveal the genetic basis of the variation and possibly preclude the effect of the environment. This is important if higher accuracy of selection is to be achieved since in breeding programs it is the heritable part of the variation that can bring about the desired genetic improvement through selection.
Variation in qualitative traits among the Tanzanian indigenous goat populations
Significant variations were observed in terms of qualitative traits of the goats across the study areas. In the present study the common colours were plain white, black and reddish brown and mixture of black and white, black and reddish brown, white and reddish brown and black, white and reddish brown. The findings are consistent with observations of Mason and Maule (1960), who reported the common colours of indigenous goats in Tanzania to be black, brown, white and grey occurring in various combinations of bi-colour or multi-colour. However, some goat populations could clearly be distinguished by a predominant colour or colour combinations. For example, Gogo, Maasai and Pare goats were predominantly white coloured though combinations of white and other colours were observed in lower frequencies. Majority of Newala were plain reddish brown while Sukuma had a mixture of black and white. Qualitative traits do not have a direct economic importance but have socio-cultural values to the communities, therefore some farmers have specific preference for some traits (Mahanjana and Cronje 2000; Gwaze et al. 2009). Due to this specific preference, frequency of some traits may be higher in the population due to unintentional selection for these traits for certain socio-cultural roles that the goats play. White coloured goats are preferred during traditional rituals or offering of spiritual sacrifices among Pare goat keepers which motivates selection and maintaining of white coloured breeding animals. Similarly, Mahanjana and Cronje (2000) reported white goats to be in high demand for sacrificial purposes, and comparatively high prices were paid for them in the Eastern Cape, South Africa. Selection for qualitative traits may automatically have an impact on quantitative traits due to genetic correlation that exists between them (Yakubu et al., 2010). Additionally, direct selection pressure exerted on animals due to differences in ecological and climatic conditions of the study areas may affect their presence and appearance as adaptive mechanisms. For example, coat colour type and patterns, presence or absence of wattle play a significant role in temperature regulation and, therefore, adaptability of the animals to the environment. Consequently, alleles controlling these features may be favoured by natural selection causing their frequency to increase in that population (Yakubu et al., 2010). Other reasons given for preference of certain colours in indigenous goats in Tanzania include security of animals during grazing (Nguluma et al, 2016) and adaptation to climatic conditions (Msemwa and Mbaga, 2018). Therefore, inter-population comparison for qualitative characteristics may result from differences in eco-geographical and sociological conditions of the areas where the goats are found.
Multivariate discriminant analysis was conducted using quantitative traits to determine the percentage assignment of each individual to their respective populations, to distinguish significant discriminating power of different traits and to obtain distances between populations. High percentages of correctly assigned individuals for Ujiji, Tanga and Newala goats is an indication of more uniformity and homogeneity of these populations which might have been caused by reproductive isolation and good production conditions. Ujiji goats are found in Kigoma region which is located in the north-western part of the country bordering DRC and historically has not experienced as much interaction with pastoralists from other regions compared with many other parts of the country due to its peripheral location. Similarly, Newala goats native to Mtwara region are located in the southern-eastern border with Mozambique which until recently had limited movement of pastoralists from other parts of the country into the region due to prevalence of cattle trypanosomosis. Tanga goats from Tanga region found in the Eastern part of the country close to the Indian Ocean has sub humid weather and with good rainfall which affect the quality and quantity of pasture forage.
On the contrary, the low classification rate of Gogo, Maasai, Pwani and Fipa goats indicates the heterogeneity of the population due to intermixing with different populations because of geographical closeness and interactions between goat keepers or similarity of production conditions. Consistent with the discriminant analysis, canonical discriminant analysis revealed that inter-population distance was small and insignificant for most of the pairs of goat populations reflecting their geographical distance and possibility of intermixing due to pastoral migrations. Even where the goat populations are not geographically close, like the case of Maasai and Fipa, the populations might be in the same ‘migration route’ which bring the animals in contact. Pastoral and agro-pastoral communities like Sukuma, Maasai, Barabaig, Kurya and Taturu were reported to be migrating with livestock in different parts of the country (Tenga et al, 2008). The Sukuma community migrated from the Lake Zone to the Lake Rukwa basin which is home to Fipa goats and later to Usangu and Morogoro plains close to where Pwani goats are found (ibid). The Maasai from the northern Tanzania migrated to Morogoro and Usangu plains before independence (Lukumbo 1998; Pingos Forum et al 2007; Walsh 2007). Implementation of programs for improvement of productivity under such situations where farmers are in constant movement and unplanned mixing of goat genotypes is difficult and unlikely to achieve any significant impact. Furthermore, due to this haphazard intermixing of animals from different agro ecologies, the diversity and unique genetic features possessed by different indigenous goat genotypes cannot be properly utilized for improvement in productivity. A study by Tenga et al. (2008) recommended a better organized, consistent and more broad-based approach in the area of policy advocacy, legal issues and investment issues for efforts to secure the animal resources that have sustained pastoralists in the past to have an impact.
Reproductive performance of the indigenous goats
Animals producing twins or triplet contribute more than 1.5 times toward meat production than the animals producing single offspring at birth (Khosa, 2012). Twinning ability has been reported to be one of the most preffered traits by goat keepers in Tanzania (Nziku et al. 2016) and it reflects the economic efficiency in meat goat industry. The average litter size of 1.82 for Ujiji goats in this study is quite comparable with some world prolific goat breeds including Nubian, Pygmy, American Alpine, French Alpine, Saanen and Toggenburg with the average litter size of 2.0, 1.9, 1.9, 1.7, 1.7 and 1.6, respectively (Amoah et al., 1996), suggesting that Ujiji goats is a prolific goat breed. Twining ability has low heritability (0.07 for triplets and 0.02 for twins) (Cottle et al, 2015) and is influenced by management. For example, Cottle et al, 2015 reported a high energy diet to be beassociated with a greater proportion of multiplebirths. Variation between Ujiji goats, the most prolific population, and Sukuma goats the least prolific was about 46% implying that crossbreeding between different goat populations would increase the prolificacy in the indigenous goats. However, increasing litter size is known to reduce birth weight of kids (Amoah et al., 1996) consequently affecting their preweaning survival. Therefore breeding for high twinning ability should be accompanied with good management of does to bring them up to a reasonable good mating weight or condition to improve litter size while providing good-sized offspring.