Perception and adaptation strategies of dairy farmers towards climate variability and change in West Africa

In West Africa, dairy production plays a vital role in the economy and the wellbeing of the population. Currently, dairy production has become vulnerable due to climate variability. The main objective of this study is to investigate dairy farmers’ perceptions and adaptation strategies towards climate variability and change in West Africa. Individual interviews and focus group discussions were conducted among 900 dairy farmers. Descriptive statistics and chi-square tests were used to assess dairy farmers’ perception of climate change. Multiple correspondence analysis and hierarchical clustering on principal component analysis were used to access the adaptation strategies of dairy farmers. The results revealed that dairy farmers perceived a decrease in the length of the rainy season and the annual rainfall but an increase in the length of the dry season and the annual temperature that affect their activities. Dairy farmers that fed the cattle mainly with natural pastures, crop residues, and agroindustrial by-products in Benin, Burkina Faso, and Niger, used as climate change adaptation strategies, transhumance in the wetland. They also used animal manure to improve fodder quality and plants to improve milk production and milk conservation. They sold milk or produced local cheese with the remaining unsold milk. Dairy farmers that mainly invested in fodder production and conservation in the climate zones of Mali, sold milk produced to dairies and cheese production units; used plants to improve milk production, pasteurization for milk conservation, and veterinary service for animal care. This study provided relevant information for West African policymakers in designing appropriate policies and programs to assist dairy farmers to improve milk production under climate variability and change.


Introduction
In Sub-Saharan Africa, the dairy sector is a major contributor to gross domestic product and plays a crucial role through the provision of healthy food and balanced diets (Moffat et al., 2016;Hahlani and Garwi, 2014). Smallholders in most developing countries produce milk, and this contributes to household livelihoods, food security, and nutrition. In addition, milk provides relatively quick returns for smallholders and is an important source of income (FAO and ECOWAS, 2018). However, dairy farmers in Sub-Saharan Africa experience more dryness and warmer temperatures; increase in warming will lead to more heat stress and engender a higher prevalence of pests and diseases . In arid and semi-arid regions of Burkina Faso, Mali, and Niger, the main agroclimatic risks for farming households are rising minimum and maximum temperatures, high rainfall variability, intense droughts, and floods (Sarr et al. 2015). The West African Sahel has experienced a general warming trend since 1950 (IPCC 2014). This warming is reflected in a decrease in the length of the rainy season and an increase in the length of the dry season between 1960 and 2010 (Ly et al. 2013). Benin studies carried out in 2011 indicated that rainfall will remain more or less stable (+ 0.2%) in the southern part of the country but will be reduced by 13-15% in the North by 2100 (MEHU 2011). According to the same study, the temperature is expected to increase between + 2.6 and + 3.2 °C by 2100. Under these scenarios, dairy farms located in these climatic zones of Benin, considered the country's favorite cattle production zone (Djènontin 2010), will suffer more from the effects of climatic variations, with expected decreases in productivity.
The effect of climatic change on dairy production is both direct through effects on the animals themselves and indirectly through effects on crop production and increased exposure to pests and pathogens (Gauly et al., 2013;Egeru, 2016). The exposure of lactating dairy cows to high ambient temperatures, high relative humidity, and solar radiation for extended periods decreases their ability to disperse heat. Warmer and drier conditions increase the likelihood of heat stress in cattle. Heat stress adversely affects reproductive performance in dairy animals (Van den Bossche and Coetzer 2008). Under heat stress conditions, lactating dairy cows exhibit several physiological responses including a voluntary reduction of feed intake, an increase in maintenance requirements, a decrease in milk yield, and milk composition (Cowley et al. 2015). Dairy cows that have experienced high temperature and humidity for a long time will reduce milk production and milk quality. Therefore, dairy farming is more and more vulnerable to climate change. As result, dairy farming levels continue to decline due to climate variability effects (Moreki and Tsopito 2013).
Most countries in West Africa are negatively affected by climate change for lack of adequate adaptation capacity (Bryana et al. 2013). Adaptation is the best way to cope with the effects of climate change (Singh et al. 2012). Moreover, climate-related risk perceptions enable dairy farmers to decide for effective adaptation of risk coping strategies (Mercado 2016;Bakhsh et al. 2018). Understanding dairy farmers' perception of climate change and how they respond to short-and long-term resilience solutions can help them withstand climate disturbances. This is a key factor in planning robust strategies for climate change mitigation and adaptation.
Before adaptation, perception of climate change, as well as its causes and effects, is important to trigger the adaptation process (Niles et al. 2016). Unfortunately, lack of adequate knowledge and information was reported in previous studies as an obstacle to adaptation and therefore calls for good quality, accurate and accessible information (Pandey et al. 2018). Knowledge is a critical ingredient and the most important input in the process Soils are mainly ferruginous. The Sudanian zone has one rainy season ranging from May to October and one dry season from November to April. The mean rainfall is 900 mm. The temperature varies from 24 to 31 °C and the relative humidity from 18 to 99%.
Burkina Faso extends between the latitudes 9° 20ʹ-15° 05ʹ N, and the longitudes 5° 20ʹ W-2° 03ʹ E. Data were collected in three climates zones (Sudanian, north Sudanian, and Sahelian zones). The south Sudanian zone is situated south of the 11° 30ʹ parallel. The rainy season here lasts six months (May-October) with average annual rainfall between 900 and 1200 mm. The mean temperature is 26 °C. The north Sudanian zone is situated within the latitudes 11° 30ʹ and 14° 00ʹ N. This zone has an average annual rainfall between 800 and 900 mm during May to August with about 29 °C. The Sahelian zone is situated in the north of 14° 00ʹ N. This zone has an average annual rainfall between 300 and 600 mm concentrated for three months (June to August). The mean annual temperature is 34 °C.
Mali is located in western Africa at a latitude of 10 to 25° N, straddling the sub-tropical band called the Sahel. Data were collected in three climatic zones: the Saharo-Sahelian, the Sahelo-Sudanian, and Sudano-Guinean zones. The Saharo-Sahelian zone is extremely dry with an annual rainfall of 100-200 mm from July to September. The temperature varies from 33-36 °C to 18-21 °C. The Sahelo-Sudanian zone (mean annual precipitation 500-700 mm) has a mean annual temperature of 30 °C. November until February is cool and dry, March to May is hot and dry, and June to September is the season of rain. The Sudano-Guinean Zone has a mean annual precipitation of less than 1200 mm. The Southern Sudanian zone has the mean annual temperatures of 27 °C and the rainy season from June to October.
Niger is located between 11° 65ʹ-23° 55ʹ N and 0° 20ʹ E-16° 00ʹ E. Data were collected in three climate zones (Saharan, Sahelo-Saharan, and Sahelian zones). The Saharan zone is located in the north of latitude 17° N with annual rainfall of less than 150 mm between July and September; the Sahelo-Saharan zone, located between the latitudes 15° N-17°N, is characterized by an annual rainfall between 150 and 300 mm from July to September. The Sahelian zone is located south of the latitude of 15° N with rainfall between 300 and 600 mm from June to August.

Sampling
The study was conducted in 15 districts in four countries. These districts were selected due to the high number of cattle, the extent of dairy farming, and milk production. In each district, the local administration involved in dairy farming was considered to provide the contact of the farmers. Random sampling was used to select the respondents in each district. Nine hundred respondents were sampled with 60 dairy farmers per district (Table 1).

Data collection
Data were collected using semi-structured interviews. The interview was conducted in local languages. Moreover, focus group discussions using semi-structured interviews were carried out with different groups (7-8 participants) of pre-selected respondents based on their availability and willingness to participate. The questionnaire was translated into the local language by interviewers especially for those that could neither read nor write French. Further information was obtained through in-depth interviews of selected respondents.
Data collected were related to information on dairy farms and characteristics, the perception of dairy farmers on climate change, and their adaptation strategies.

Data analysis
Descriptive statistic and chi-square (χ 2 ) analyses were used to assess the independence between the climate zones and countries on the answers to close questions related to the perception about the variation in the length of the seasons (rainy and dry season), the variation in the annual rainfall and temperature. The same analysis was used to assess the independency between the climate zones and countries on the answers close questions related to the perception about the impact of climate change on herd size, livestock fertility, amount of milk produced, fodder availability, microbial proliferation, and milk rapid fermentation, the milk quality in terms of color and the fresh milk conservation.
Dairy farmers' adaptation systems for climatic change were first assessed with multiple correspondence analysis (MCA) performed on individual answers and then used the MCA factorial axes in a hierarchical clustering on principal component analysis (HCPC). A chisquare test (χ 2 ) was used to test the independence between clusters and climatic zones. The analyses were conducted in R software version 3.5.2 (R Core Team 2019). MCA and HCPC were run using packages ade4 (Dray and Dufour 2007), FactomineR (Lê et al. 2008), and Factoextra (Kassambara and Mundt 2016).

Perception of dairy farmers on climate change
The dairy farmers' perception of climate change varied significantly by country and climate zones. The farmers significantly perceived a change in the length of the rainy and dry seasons with a decrease in the rainy season and the annual rainfall but an increase in the dry season and the annual temperature (Table 2).
With regards to the impact of climate change on dairy farmers' activities, the farmers perceived in general a decrease in herd size with exception of an increase in the two climate zones of Burkina-Faso (Sudanian and Sudano-Sahelian zones) and the Guinean zone of Benin (Table 3). The livestock fertility was also perceived to decrease with exception of the two climates zones in Burkina-Faso, the Guinean and the Sudano-Guinean zones in Benin. The amount of milk produced, the availability of fodder, and the milk color were perceived to decrease while the proliferation of microbial and rapid fermentation of milk was perceived to increase (Table 3).

Typology of dairy farmers systems
The MCA and HCPC output revealed three groups of dairy farming systems with 60.25% of the information recorded on all farmers. The first group represented 63.38% of the sample (n = 552) and their main objective (73.35% of the farmers) was the sale of milk produced to milk collectors. They depended mainly on natural pastures and mineral supplements (mineral lickstones) for cattle feeding in addition to the collection and use of bush straw. They were married and unschooled. However, 16.80% of them received literacy classes in their own local language. In total, 67.74% were under 50 years old and 58% older than 50 years old. Dairy farmers of this group were also known for their periodic transhumance with the large part of the cattle and kept a small part of cattle on-site for their household milk supply. Regarding their herd structure, they had 58.2% females and 41.8% males with the dominance of young males (male caves and subadults bulls) compared to young females (female calves and heifers). The proportion of cows was higher than reproductive bulls. Their herd size was 147 ± 15. This group of dairy farmers was dominant in all countries and climate zones (Fig. 2), with a significant proportion in Niger (Sahelian and Sahelo-Saharan zones), Burkina Faso (Sudanian zone), and Mali (Sudanian zone).
The second group represented 19.75% of the sample (n = 172) and their main objective (65.44%) was the traditional processing of milk into local cheese. They used mainly crop Fig. 2 Relation between clusters of dairy production systems, climatic zones, and countries. GZ, Guinean zone; SGZ, Sudano-Guinean zone; SZ, Sudanian zone; SSZ, Sudano-Sahelian zone; ShZ, Sahelian zone; ShSaZ, Sahelo-Saharan zone residues, agro-industrial by-products, and natural pastures to feed the cattle. Some farmers in this group (22.35%) sell milk produced to small diaries or milk processing units. Some of the dairy farmers (49.33%) in this group completed primary education. The majority of them (75.20%) received also literacy classes in their local language. The animal categories in the herd structure showed significant variations (p < 0.001) with a high proportion of cows (67.6%). Their head size was 115 ± 13. This group was in minority in all climatic zones. Their proportion was high in Sahelo-Sudanian zones of Burkina Faso, Sudanian zone of Benin, Guinean zone of Mali and Benin. This group was almost absent in the Sahelian zone of Niger and the Sudano-Sahelian zone of Burkina Faso (Fig. 2).
The third group represented 16.88% of the sample (n = 147) and their main objective (90.32%) was the sale of the milk produced to dairies and cheese production units. In total, 88.89% of dairy farmers in this group invested in fodder production. They conserved the fodder using silage technology. They also used crop residues and agro-industrial by-products to feed their livestock. They had little mobility. Some of them (8.82%) used the milk to produce local cheese traditionally. Only 8% of the dairy farmers of this group received literacy classes in the local language. The animal categories in the herd structure showed significant variations (p < 0.001) with a high proportion of cows (70.5%). Their herd size was 47 ± 20. Dairy farmers of this group were in low proportion in all climatic zones but abundant in Sahelian, Sudanian, and Guinean zones of Mali, Sahelo-Saharan zone of Niger, and Sudano-Guinean zone of Benin (Fig. 2).

Typology of adaptation strategies developed by dairy farmers
The MCA and HCPC output on the adaptation strategies developed by dairy farmers including strategies for livestock feeding during the dry season, water supply, milk production, and conservation revealed three groups of adaptation strategies with 60.25% of the information recorded on all farmers.
The first group represented 38.92% of the sample (n = 339). In this group, the farmers fed the cattle during the dry season with transhumance in wetlands and spread animal manure in dried natural pastures to improve fodder production and their nutritional value. They harvested rainwater and used natural water supplies (streams, rivers, marshes, swamps, wetlands, and shallow water) as adaptation strategies for water supply. Dairy farmers surveyed reported using galactogenic plants including the leaves of Sorghum bicolor, Spondias mombin, Annona senegalensis, Daniellia oliveri, Vitellaria paradoxa, and Euphorbia hirta (Fig. 4A) to increase milk production. Essential oils and nectar extracted from Calotropis procera, Carica papaya, and Balanites aegyptiaca (Fig. 4B) were used to conserve the milk in order to avoid the rapid fermentation or even spoilage of the milk as well as the processing of the milk into local cheese. Plants used to control milk fermentation included Calotropis procera, Ocimum gratissimum, Cymbopogon citratus, Pimenta racemosa, and Zingiber officinale (Fig. 4B). Medicinal plants were also used to treat animal diseases. This adaptation system was mostly used by dairy farmers in the Guinean, Sudanian, and Sudano-Guinean zones of Benin (Fig. 3).
The second group represented 24.23% of the sample (n = 211). In this group, farmers fed their cattle during the dry season with fodder and silage. Treatment of bush straw with urea was also used to improve their nutritional value. To cope with water supply issues in the dry season, the sink of boreholes and wells in dry places were used.
Galactogenic plants including Euphorbia hirta, Spondias mombin, Secamone afzelii, Ficus sycomorus, Mucuna pruriens, and Annona senegalensis (Fig. 4A) were used to increase the amount of milk produced by the cattle. Pasteurization was used to conserve the milk against its rapid fermentation, and veterinary service was used for animal care. This adaptation system was mainly used by dairy farmers in Guinean, Sudanian, and Sahelian zones of Mali, as well as dairy farmers in the Sudanian zone of Burkina Faso (Fig. 3).
The third group represented 36.85% of the sample (n = 321). In this group, the farmers fed the cattle during the dry season with crop residues and mineral supplements (lickstones). They reduced the herd size by selling some young bulls and cull cows to overcome feeding difficulties. In addition, herd diversification with sheep and goats was also used as a strategy to address feeding issues. To improve cattle ration, supplements based on oilcakes or multi-nutritional blocks were used. For water supply, they used community pastoral wells and dams in addition to water purchase at the village public water pump. Galactogenic plants including Spondias mombin, Balanites aegyptiaca, Ficus gnaphalocarpa, Pergularia tomentosa, Annona senegalensis, Daniellia oliveri, and Boswellia dalzielii (Fig. 4A) were used to increase the milk produced by the cattle. The milk was immediately sold to dairies and milk processing units or stored in appropriate calabashes/wooden gourds made with Pterocarpus erinaceus, Acacia nilotica, and Balanites aegyptiaca, to overcome milk fermentation (Fig. 4B). Moreover, essential oil and juice extracted from the leaves of Calotropis procera, Annona senegalensis, and Carica papaya were also used to control milk fermentation. This adaptation system was mainly adopted by dairy farmers in Sahelian and Sahelo-Saharan zones of Niger, as well as dairy farmers in Sahelo-Sudanian zones of Burkina Faso (Fig. 3).

Relationships between dairy farming systems and adaptation strategies
The relationship between dairy farming systems and adaptations systems (Fig. 5) revealed that dairy farmers transhumant that used natural pastures and mineral lickstones to feed the cattle and sold the milk produced to milk collectors (group 1) in the climate zones of Benin, Burkina Faso, and Niger, used as adaptation strategies towards climate change, transhumance in wetland, improve fodder production and quality with animal manure; plants to improve milk production and conservation and to treat animal disease, (adaptation system 1) in addition to the use of crops residues, mineral supplements, herd size reduction; water supply with community pastoral wells and dams as well as to purchase water; plants to improve milk production and conservation in addition to immediate milk sale (adaptation system 3).
The dairy farmers that used mainly crops residues, agro-industrial by-products to feed the cattle; sold the milk produced and collected and also used to transform the milk in local cheese (group 2) in the climate zones of Benin used the adaptation system 1 only towards climate change.
The dairy farmers that mainly invested in fodder production and conserved the fodder using silage technology sold the milk produced to dairies and milk processing units and also used to transform the milk in local cheese (group 3) in the climate zones of Mali; used as adaptation strategies towards climate change, fodder production, conservation or treated with urea to feed their cattle in the dry season. They also used plants to improve milk production, pasteurization for milk conservation, and veterinary service for animal care (adaptation system 2) (Fig. 5).

Perception of dairy farmers on climate change
The dairy farmers in the four countries and the six climate zones perceived a decrease in the rainy season and the annual rainfall but an increase in the dry season and the annual temperature. Annual rainfall decrease was less perceived by dairy farmers in the Guinea zone of Benin and the Sudano-Guinean zone of Mali. This could be explained by the decline of rainfall as one ascends from the Guinean zone to the Saharan zone. Results from several studies revealed an increase in temperature and a decrease in rainfall across many African rural regions (IPCC 2014; Debela et al. 2015). In most West African countries, climate change effects are characterized by recurrent droughts, altered rainfall regimes with deficits in the order of 20-30%, and decreases in stream-water flows (Sarr et al. 2012). Similar perceptions on climate change were reported in previous studies (Debela et al., 2015;Kosmowski et al. 2016). In contrast, other studies indicated an increase in rainfall amounts that lead sometimes to flooding (Mertz et al. 2009(Mertz et al. , 2012Sofoluwe et al. 2011).
The farmers perceived that increased temperature is related to the decrease in rainfall and induces a decrease in herd size, livestock fertility, milk production, fodder availability, Fig. 5 Correspondence factor analysis on the relationship between production and adaptation systems. P, production system; A, adaptation system; GZ, Guinean zone; SGZ, Sudano-Guinean zone; SZ, Sudanian zone; SSZ, Sudano-Sahelian zone; ShZ, Sahelian zone; ShSaZ, Sahelo-Saharan zone and milk conservation but an increase in the proliferation of microbial and rapid fermentation of milk. During the dry season, temperature causes a large part of rainfall evaporation. Livestock production would be severely affected in a region where increased temperature is related to a decrease in rainfall (Sirohi and Michaelowa 2007). The frequent droughts lead to the drying up of the natural pastures and induce severe livestock feeding issues. The increase in temperature has a significant impact on water availability and pasture resources including fodder quantity and quality, animal and rangeland biodiversity, management practices, and production systems (Herrero et al. , 2010. The decrease in milk production in terms of quantity and quality may be a consequence of the persistent drought conditions that lead to a reduction of fodder during the lactation period of dairy cows. An increase in temperature and recurrent drought periods adversely affect milk production and cattle growth (Hidosa and Guyo 2017;Kimaro et al. 2018). Moreover, an increase in temperature facilitates the appearance and proliferation of certain parasites and diseases that may reduce milk production as air temperature has a significant direct effect on animals' health, milk production, and reproduction rate (Herbut et al. 2018;Mustafa et al. 2019). Exception of increase in herd size and livestock fertility was perceived in the two climate zones of Burkina-Faso (Sudanian and Sudano-Sahelian zones) and the Guinean zone of Benin. This might be due to the high presence in these areas of pastoralists' transhumant from other dry regions of West Africa. The availability of fodder, in quantity and quality, is a crucial factor for pastoralism in the Sahel; many herders transhumant move to wetlands (Deygout et al. 2012). The pastoral areas of Benin host every year national and trans-border transhumant herders with a very large number of herds. The factors determining the choice of Sudanian regions of Benin as favorite destinations for West African transhumant herders remain the availability of fodder and water resources (Kagoné et al. 2006). In Benin, the Upper Alibori classified forest is today one of the favorite destinations for national and foreign transhumant herders, and the agricultural and pastoral pressures on the resources of this forest are increasing (Assani et al. 2017). Several studies also pointed out that the Regional Park W and other protected parks in northern Benin are under strong pressure from transhumant herds (CORAF/WECARD, 2015; Gado et al. 2020). Entry into the pastoral areas of the Guinean and Sudanese regions of Benin began with the 1973 and 1984 droughts Lees 2004 andBoutrais et al. 2008) and the eradication of tsetse flies which forced transhumant herders from the Sahel (Niger and Mali) to move into the protected areas of northern Benin. All this has contributed both to the increase of herd size and livestock fertility.

Adaptation systems adopted by dairy farmers towards climate change
Three types of dairy farmers systems were observed with different objectives. Only the first system was used to sell the total milk produced while the two other systems were used to transform the milk into local cheese in addition to milk sale. The difference observed in the objectives may be due to the livestock feeding mode. In the first system, the farmers are transhumant and use natural pastures and mineral lickstones to feed the cattle, while in the other systems, they use mainly crops residues, agro-industrial by-products (group 2) and invested in fodder production and conserved the fodder using silage technology (group 3) to feed the cattle. The dairy cow feeding mode or practices has a great impact on milk composition and cheese production. For example, goats fed a high concentrate level with pasture grazing produced milk with significantly higher contents of fat, protein, and total solids and thus had a higher cheese yield than goats grazed pasture alone without concentrate supplementation or under a confined feeding system with concentrate but without pasture grazing (Soryal et al. 2004). Cheeses made from the milk of cows fed sunflower cake have a high-fat content (Zhang et al. 2006). This is because the composition of milk fatty acids is often affected by rumen biohydrogenation and conversion of the enzyme D9-desaturase (C18:0 to C18:1, Bauman and Griinari 2003), but the large changes of milk fat composition can be achieved by changing the nature of forages in the diets. For example, Chilliard et al. (2007) reviewed data relating to the fatty acid composition of milk from animals fed hay, fresh grass, and maize silage and reported changes to the content. Diets formulated with higher quality forages increased the milk fat content and milk yield of dairy cows, whereas low-quality forages containing fewer nutrients would result in the reduction of milk yield and a decrease in milk fat synthesis (Zhu et al. 2013). The composition and physical characteristics of milk influence its processability for products such as cheese. The two most important milk solids in cheese making are protein (particularly casein) and fat (Amenu and Deeth 2007). These aforementioned milk components vary according to the diet of the dairy cows and justify the choice of the dairy farms' objectives (milk or cheese) based on the feeding mode.
Three types of adaptation systems were observed based on the solutions used to cope with issues related to livestock feeding, access to water, and milk quantity and its conservation. The adaptation system 1, mainly depending on natural resources, used crops residues and agro-industrial by-products to feed the herd, a rainwater-harvesting system for water supply and milk/cheese flash pasteurization with some plants for conservation. Adaptation system 2 used silage technology and mineral lickstones to feed the herd, sinking well or boreholes for water supply and milk flash pasteurization for conservation while adaptation system 3 used fodder treat with urea to feed herd; purchase of water for water supply and flash milk pasteurization with sodium bicarbonate for conservation. The livestock feeding strategy based only on natural vegetation or use of crops residues and mineral supplements is more vulnerable to climate change compared to the feeding strategy based on fodder and silage production. High temperatures tend to increase lignification in plant tissues and hence decrease the digestibility of forage and concurrently induced a shift from C3 grass species to C4 grasses which has direct implications for forage supply (Tubiello et al. 2007). Similarly, when the climates become hotter and drier; pasture composition is likely to shift to species that may be less suitable for grazing (Escarcha et al. 2018). Lower the climate change affects the productivity and grazing capacity of rangelands, higher the nutritional stresses in livestock are likely to suffer, further exacerbating the existing vulnerability of pastoral systems (Hidosa and Guyo 2017) As grasses and legumes from natural grazing areas decline in quality and quantity during the dry season, forages should be conserved in form of hay and silage to ensure adequate forage supply during scarcity in the dry season (Lamidi and Ologbose 2014). The performance of ruminant animals which is dependent on the native pasture is seriously impaired with the long droughts; the quality is associated with the fibrous and lignified nature of the pasture which limits intake, digestibility, and utilization (Olafadehan and Adewumi 2009;Lamidi et al. 2013). Conserving forage as silage is an option to alleviate feed constraints and maintain animal productivity during dry periods (Reiber et al. 2010). Moreover, in areas with a long dry season, tropical pastures rarely provide sufficient year-round feed of reasonable quality to match the nutritional demands of livestock and support satisfactory livestock production and reproduction (Reiber et al. 2010). The use of by-products for supplementary livestock feeding is justified when the forage supply is inadequate for animal needs either in terms of quantity or quality (Bogoro et al. 2006;Aina et al. 2012). Increased usage of silage-making technology using improved forages and feeds to overcome the dry season feed deficits in the dry tropics seemed possible by application of appropriate technology transfer strategies (Reiber et al. 2010). Farmer motivation and participatory technology experimentation, evaluation, and development were particularly important in areas where silage was less known. Once there are positive examples, adapted and efficient silage technologies should be scaledout through demonstrations and exchange of experiences ('promotion of adoption' and/ or farmer-to-farmer approach). The water supply with only natural water supplies is also vulnerable. In arid and semiarid regions, precipitation is generally lower than potential evaporation and non-uniform distribution, resulting in frequent drought periods (Oweis and Hachum 2009). As the water shortage in dry areas is a recurring crisis, capturing rainwater and making effective use of it is crucial. Water harvesting can play an important role in fulfilling the objectives of such agricultural or livestock projects. Farmers need information on how to capture and use every available drop of water efficiently (Oweis and Hachum 2009).
The three systems use galactogenic plants to increase milk production. An effective nutritional regime and use of herbal galactogogues act synergistically to enhance milk yield which would prompt a good augmentation in the productivity of the dairy herd. Herbal galactogogues act through interactions with dopamine receptors by exerting an influence through adreno-hypothalamo-hypophyseal gonadal axis resulting in enhanced prolactin concentration and thereby augmenting milk production (Gbadamosi and Okolosi 2013;Mohanty et al. 2014). Thus, these galactogenic plants (booster for lactation) constitute an alternative to improve milk production and cope with climate change's effects on milk yield. In order to restore animal productivity and to optimize the milk production in individual animals for better profits, various herbal preparations, hormones, mineral supplements, and feed additives have been tried (Ramesh et al. 2000;Bhatt et al. 2009). Galactin, a non-hormonal herbal preparation, significantly enhanced milk production in dairy cows and ultimately improved dairy economics (Ramesh et al. 2000;Kumari and Akbar 2006). Herbal preparations have also been shown to relieve the heat stress in dairy cows and ultimately improve their productivity (Zhang et al. 2006). Indigenous herbal preparations effectively restored the altered milk constituents and increased the milk production in cows with sub-clinical mastitis (Kolte et al. 2008). Thus, it is important to set up a domestication program on these plants in order to sustain their conservation and use for dairy production. Except in adaption system 2 where the milk is pasteurized for conservation, the other systems use plants for milk conservation. It is important to set up domestication of the plant used to conserve milk in order to sustain the use for dairy production. The use of plant extracts and essential oils in consumer goods is expected to increase in the future because volatile oils can be considered as a natural alternative to synthetic food preservatives and could be used to enhance food safety and shelf life (Samaddar et al. 2015). However, our study revealed that the use of plant species for milk conservation is more vulnerable than pasteurization. This can be explained by the fact that it's difficult to define and measure the specific quantity of plant material to be added, to ensure an expected antimicrobial effect in food, in addition to the need for analytical methods for a more accurate determination of these compounds (Calo et al. 2015). The stability of natural compounds must also be taken into account when they are added to food. Such compounds are usually sensitive to oxygen, light, temperature, and pH (Dima and Dima 2015) and may be lost during milk preservation, cheese processing, and preservation. Libran et al. (2013) observed a decrease in the content of compounds from Ocimum basilicum (basil) and Tanacetum vulgare (tansy) added during the production of cheese. Similarly, 37.49% of the total volatiles of rosemary essential oils (Rosmarinus officinalis) added to sheep milk were lost during cheese production, as a certain portion was lost in the whey (Moro et al. 2015). Thus, the concentration of plant extracts and essential oils to be incorporated into cheese must supply the possible losses during production and interaction with food, in order to provide adequate microbiological inhibition (Hassanien et al. 2014;Moro et al. 2015). Pasteurized milk has suitable nutrition value for daily use, but its shelf life is only 2 weeks under refrigeration at 4 °C (Nasr and Elshaghabee 2019). However, the synergistic effect of Nisplin® combination in emulsion with natural essential oils extracted from plants such as cinnamon (Cinnamomum cassia), clove (Syzygium aromaticum), ginger (Zingiber officinale), and jojoba (Simmondsia chinensis) as safe food additives extend the shelf life of pasteurized milk under poor refrigeration conditions at 10 °C and help to achieve commercial and social benefits for the community (Nasr and Elshaghabee 2019). The combination of pasteurization and the use of essential oils or plants latex is the best strategy to conserve milk in the rural areas of the climate regions studied across West Africa.
The first and the third adaptation systems use medicinal plants for livestock care while the second adaptation system relies on veterinary service. Conventional veterinary and ethnoveterinary medicine, even by taking into account their heterogeneity, must act jointly to realize their shared goal which is the preservation of the health and welfare of animals (Davidović et al. 2012). Medicinal herbs, along with some other herbs, are used both separately and as an additional therapy to conventional drugs which can, in this case, thanks to the action of active plant ingredients, be used in lower, safer doses. It is possible to direct curative effect of plants in a certain direction, to strengthen or alleviate their action by combining certain features of some plants and their preparations (Gerzilov et al. 2011). In many rural communities of developing countries, dairy farmers' use of plants as veterinary medicines is very common. Most of them depend on traditional or folk medicines or household remedies for the treatment of diseases from which they themselves or their domestic animals suffer (Das and Mohanty 2006). The first adaptation system was mostly used by dairy farmers in Guinean, Sudanian, and Sudano-Guinean zones of Benin. The second adaptation system was mainly used by dairy farmers in Guinean, Sudanian and Sahelian zones of Mali, as well as dairy farmers in the Sudanian zone of Burkina Faso. The third adaptation system was mainly adopted by dairy farmers in Sahelian, Sahelo-Saharan zones of Niger, as well as dairy farmers in Sahelo-Sudanian zones of Burkina Faso. It's clear that adaptation strategies varied depending on climate zones and countries as well as the dairy farmer's production targets, livestock structure, demographic characteristics, and available resources. This should be taken into account in the elaboration of the sustainable adaptation strategy towards climate change for dairy farmers.

Conclusion
Dairy farmers in West Africa currently perceive a decrease in the rainy season and rainfall but an increase in dry season and temperature. This has induced a decrease in herd size, livestock fertility, milk production, fodder availability, and milk conservation but an increase in the proliferation of microbial and rapid fermentation of milk.
Dairy farmers that feed the cattle mainly with natural pastures and agricultural products in the climate zones of Benin, Burkina Faso, and Niger used transhumance in wetlands as climate change adaptation strategies. They used animal manure to improve fodder production and quality as well as some plants to improve milk production, conservation, and to treat animal disease. They also used to sell the milk or produce local cheese with a part. Moreover, they used crop residues, mineral supplements, herd size reduction, and water supply with community pastoral wells and dams, and purchased water.
Dairy farmers that mainly invest in fodder production and conservation in the climate zones of Mali sell the milk produced to dairies and cheese production units; use plants to improve milk production, pasteurization for milk conservation, and veterinary service for animal care.