4.1 Perception of dairy farmers on climate change
The dairy farmers in the four countries and the six climate zones perceived a decrease of the rainy season and the annual rainfall but increase of 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 declining 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, 2012; Sofoluwe et al., 2011).
The farmers perceived that increase temperature is related to the decrease in rainfall and induce a decrease on herd size, livestock fertility, milk production, fodder availability and milk conservation but increase of 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 increase temperature is related to 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 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., 2009, 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. Increase in temperature and recurrent drought periods adversely affect milk production and cattle growth (Hidosa and Guyo, 2017; Kimaro et al., 2018). Moreover, increase in temperature facilitates the appearance and proliferation of certain parasites and diseases that may reduce the milk production as air temperature has significant direct effect on animals’ health, milk production and reproduction rate (Herbut et al., 2018; Mustafa et al., 2019). Exception of increase on 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, being a crucial factor for pastoralism in the Sahel, many herders transhumant move to wetlands (Deygout and Treboux, 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 (Toutain et al., 2004 and Boutrais, 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.
4.2 Adaptation systems adopted by dairy farmers towards climate change
Three types of dairy farmers systems were observed with different objectives. Only the first system used to sell the total milk produced while the two others systems 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 others 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 acids 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 process ability 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 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 et al., 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 (Borogo et al., 2006; Aina, 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 scaled-out 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 in 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 productivity of dairy herd. Herbal galactogogues act through interactions with dopamine receptors by exerting an influence through adreno-hypothalamo-hypophysealgonadal 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 effects on milk yield. In order to restore the 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 ; Bhat et al, 2009). Galactin a non-hormonal herbal preparation significantly enhanced the milk production in dairy cows and ultimately improved the 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 is important to setup a domestication program on these plants in order to sustain their conservation and use for the dairy production.
Except in adaption system two where the milk is pasteurized for the conservation, the others systems use plant for milk conservation. It is important to setup a domestication of the plant use to conserve milk in order to sustain they 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 of analytical methods for a more accurate determination of these compounds (Calo et al., 2015). 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, 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 two 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 plant 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 plant for livestock care while the second adaptation system relies on veterinary service. Conventional veterinary and ethnoveterinary medicine, even by taking into account their heterogenosity, must act jointly to realize their shared goal which is the preservation of 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 are 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 from (Das et al., 2011).
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 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.