Effect of Season and Age on Dry Matter Intake in Female Camels on Sahara Rangelands of Algeria

Camels are important livestock species that significantly contribute to the livelihood of the pastoralists in the arid and semi-arid areas. In Algeria, the dromedary has a great interest in the various Saharan regions, because it occupies a preponderant place in the economic and social life of the Saharan populations (Senoussi, 2012; Faye et al. 2017: Hamad et al. 2018). It also has a positive ecological impact on the valuation, rational use and preservation of vegetation cover of Saharan rangelands (Khenfer et al., 2019; Julien et al. 2021).
       
Today, the dromedary is affected by the scarcity of natural food resources and the feeding of camel herds on the rangeland to be a source of great difficulties for the breeders. As such, feed becomes the most important single factor affecting productivity of camels. According to Kuraz, et al. (2021) the global climate change is a pressure to animal production due to the impact on forages quality and water availability.
       
This is why one of the questions considered urgent is to be able to determine continuously all the indicators of dromedary farming, especially those concerning its feeding on rangeland, because the dromedary feeding seems little known as compared with the studies carried out in sheep, goats and cattle. Camels are both grazers and browsers of a broad spectrum of preferred for ages whose nutrient composition is not well documented (Ikanya, 2022).                                            
 
Moreover, it is necessary to understand the foraging behavior of dromedaries in order to predict their impact on the vegetation and their nutrient requirements. Furthermore, management and use of range plants in camel feeding systems require a good knowledge of seasonal variation on their intake.
       
The aim of the study was to determine the impact of seasonal variation on intake in female camels to satisfy its dry matter and nutrient requirements and for better management of the animal and its habitat.

Study area
 
The study was conducted in the area of El Alia (32°41' 51"  N, 5°25' 32" E), El Hedjira town, a major rangeland in northern Algerian Sahara (Fig 1). The area experiences hot arid climatic conditions, characterized by such as high temperatures, salinity and drought (Trabelsi et al. 2020) The main plant species of the site are, Anabasis articulata, Salsola tetragona, Retama retam, Moltkiopsis ciliata, Tamarix galica, Limoniastrum guyonianum and Traganum nudatum, these species are widely available and highly preferred by ruminants (sheep, goats and camels) in its natural habitat (Lakhdari et al., 2015). So the energy productivity of El-Alia rangeland remains appreciable. This gives it an important pastoral interest (Mayouf et al., 2017).


 
Monitoring of animals and estimating forage intake
 
The experimental study was conducted throughout the two seasons (dray and wait). During each season, sixteen female camels were randomly selected and marked from the two categories, youngs (2-4 years) and adults (>4 years). So that 01 animal / day / category/ season was selected. Thus, 64 animals were observed from October 2015 to July 2016.
       
Forage intake for each preferred plant species was estimated by multiplying bite counts by the average mass per bite, after cutting and weighing simulated bites that represent bite ingested (Cook, 1963; Meuret et al., 1985; Dumont et al., 1995). Forage consumption was quantified by the bite count technique (Wallmo and Neff, 1970; Gauthier-Pilters and Dagg, 1981). In this technique, an animal was closely followed for 20 min each one hour during feeding throughout the day, the number of bites made on the preferred plant species (Lakhdari et al., 2015) were recorded when the observers were close enough (3-5 m) to ensure accurate identification of the plant and parts diets consumed.
The dry matter intake (DMI) is given by the formula:
DMI: Dry matter intake.
GT: Total grazing time.
R: Total counting time.
TNBi: Total number of bites made on species i.
WBi: Weight of the bite made on species i.
       
This study was carried out by the Scientific and Technical Research Centre for Arid Areas (CRSTRA), Biskra, Algeria.
 
Statistical analysis

Different experimental groups (the number of bites on each preferred plant species by each category of female camels and Intake) were compared with the Univariate ANOVA followed by Bonferroni’s test for comparisons post hoc. A probability level of P<0.05 was considered to be statistically significant. The SPSS software package (SPSS Ver. 15.0, SPSS Inc., Chicago, Illinois) was used for all tests.

For adult females, the number of bite counts was in the range of 6 to 43 (average= 26.5±19.8) bite counts in the wet season and 32 to 87 (average= 63.3±23.5) bite counts in the dry season. For young females, the number of bite counts was in the range of 4 to 35 (average= 16.8±12.5) bite counts in the wet season and 12 to 67 (average= 29.7±20.9) bite counts in the dry season.
       
During the wet season, for adult females, bite weight ranged from 0.7 g recorded for Salsola longifolia to 3.2 g recorded for Traganum nudatum, while for young females, bite weight ranged from 0.66 g recorded for Anabasis articulata to 1.62 g recorded for Traganum nudatum. During the dry season, the bite weight ranged from 0.72 g recorded for Anabasis articulata to 2.67 g recorded for Traganum nudatum and 0.65 g recorded for Anabasis articulata to 1.55 g recorded for Limoniastrum guyonianum for adult and young females respectively.
       
The monitoring individual feeding behavior and direct observation method used has permitted the recording of bite counts, bite weight and the evaluation of the female camels’ intake. The results revealed that the preferred species show a variability in the number of bits (p<0.05), so it is clear that in the dry season, Anabasis articulata is very grazed as it occupies the second position for adult and young female camels categories with a number of bites (84) and (39) respectively. While in the wet season, the number of bites made on Anabasis articulata decreases to the half for both categories. The study conducted by Benseddik (2011), in the Ouargla region confirmed that the palatability of this species is very strong only in winter.
       
The study exhibited that in wet season, Traganum nudatum, is the most grazed by adult and young females with a maximum of 57 and 35 bites respectively, also in the dry season it is very appetizing, this result is confirmed by Benseddik (2011), who reported that the palatability of Traganum nudatum remains high even if the plant is desiccate. Limoniastrum guyonianum grazed very little in winter with 6 bites for adult females and 4 bites for young females, but in the dry season, it becomes the most grazed with 87 and 67 bites respectively for adult and young females.
       
Our results fall within the broad range of the study conducted by Benguessoum  and  Bouhamed (2006), on the number of bites per species, reported that the number ranging from 60 to 100 for Stipagrostis plumosa, from 20 to 29 for Savignia longistila and from 20 to 30 bites for Helianthemum lippiias, well our observations concurred with the reports of Kuria et al. (2012). Slimani et al. (2013), reported a maximum 2 to 5 bites for each species. Generally, the difference in bite counts may be attributed to forage abundance, where camels concentrated on browsing and the movement was minimal (Kassily, 2002).
       
Overall, there is a significant difference (p<0.05) in the average number of bites between seasons, it is higher in the dry season, 63.3±23.47 whereas 26.5±19.78 in the wet season for adult females, while it is 29.7±20.92in the dry season and 16.8±12.47.
       
The season significantly influences the number of bites, which is a maximum in the dry in the wet season for young females. The season significantly influences the number of bites, which is a maximum in the dry season. Penning (1986) and Distel et al. (1995) suggest that the animals try to compensate the small quantity taken by bite by increasing the frequency of bite in order to maintain their intake. Mebirouk (2014), reports that the average number of bites is changed inversely proportional to the weight of the bite: the number of bite increases when the weight of the bite decreases. The seasonal influence on chemical composition and digestibility of the most selected forage species
       
Regarding the intake quantity for adult females (Fig 2), in the wet season, Traganum nudatum recorded the highest amount with 182.4 g/day, followed by Salsola tetragona and Anabasis articulata with an estimated intake 63.8 and 53.7 g/day respectively. The lowest intakes were recorded in Limoniastrum guyonianum, Moltkiopsis ciliata and Salsola longifolia 19.3, 14 and 11.9 g/day respectively. In the dry season, the highest intake is estimated in Traganum nudatum 216.3 g/day followed by Limoniastrum guyonianum with 106.1 g/day, while the Moltkiopsis ciliata recorded the lowest ingested amount 35.5 g/day.


       
For young females (Fig 3), the highest quantity intake in the wet season recorded in Traganum nudatum 56.7 g/day, the lowest intakes are estimated for Moltkiopsis ciliata and Limoniastrum guyonianum 4.5 and 3.1 g/d respectively. In the dry season, the highest intakes were estimated for the species Moltkiopsis ciliata and Salsola tetragona 13.3 and 12.3 g/day respectively.


       
The results obtained for adult females showed that during the wet season the highest daily dry matter intake recorded for Traganum nudatum 1.9 kg DM followed by Salsola tetragona with 0.38 kg DM then Anabasis articulata with 0.32 kg DM (Fig 4).


       
The lowest quantities were recorded for Limoniastrum guyonianum and Salsola longifolia 0.08 and 0.07 kg DM respectively. However, in the dry season, Traganum nudatum precedes with an estimated quantity of 1.3 kg DM, followed by Limoniastrum guyonianum with 0.64 kg DM. Very similar quantities were recorded for Salsola tetragona and Anabasis articulata 0.38 and 0.36 kg DM respectively, the lowest quantity was recorded for Moltkiopsis ciliate with 0.21 kg DM. Species Anabasis articulata and Salsola tetragona do not showed significant seasonal variability in the amount of dry matter intake.
       
Concerning young females, in the wet season, the highest daily dry matter intake recorded for Traganum nudatum 0.34 kg DM, the lowest dry matter intake was recorded for Limoniastrum guyonianum 0.02 kg DM.0.018 and 0.11 kg DM were recorded for Salsola tetragona and Anabasis articulata respectively. In the dry season, the highest daily dry matter intake recorded for Limoniastrum guyonianum 0.45 kg DM. Traganum nudatum recorded only 0.26 kg DM followed by Anabasis articulata and Salsola longifolia, with 0.15 and 0.11 kg DM respectively, while Salsola tetragona recorded the lowest quantity with 0.07 kg DM (Fig 5).


       
Regarding the quantity of dry matter intake (DMI), the study showed a difference in the amount of dry matter intake between seasons (p<0.05). According to Cross (1977), the dromedary intake at pasture varied from 4.8 to 11.4 kg DM/day, this seasonal variation was also mentioned by Lechner-Doll et al.(1990);  Migongo-Bake (1992) and Longo et al., (2007), they reported that the quantity of dry matter intake at the pasture is affected by the season.
       
AitHamou (1993) reported that the female camels intake decreases from 3.2 kg DM/day/animal in the dry season to 2.06 kg DM/day/animal in the wet season. (Ben Arfa et al., 2014) reported that the female camels’ intake decreases remarkably in winter, which confirms our results (3.2 kg DMI /d/ animal in the dry season and 2.06 kg DMI/d/animal in the wet season). (Ben Arfa et al., 2014) reported that mean intake in adult female camels are 6 kg DM /d/animal for all grazed species. In order to adequately cover its needs, the she-camel should consume a large amount of DM (Laameche et al., 2019).
       
Our results remain in the intake range of the vegetation at pasture since they represent only the preferred species: Traganum nudatum, Limoniastrum guyonianum, Anabasis articulata, Moltkiopsis ciliata, Salsola tetragona and Salsola longifolia. In the wet season, the decrease in the dry matter intake of the preferred species is linked to the existence of ephemeral species that allow the camels to eat better and to diversify their food rations. Sagala et al. (2020) reported that that there were species and seasonal differences in forage preferences and that the preferred species were high in crude protein content and in-vitro dry matter digestibility. On the other hand, these ephemeral species disappear during the dry season, which makes the food choice of camels limited. Thus they try to compensate for this lack by increasing the intake of the preferred species available. According to Salamula et al. (2017) camels could have adequate forage even in the face of climate change. Dumont (1996) reported that the herbivores food choices are at least partly dictated by the desire to maximize their energy balance.

The major conclusion of this study is that for the female camels, there are seasonal variations in the amount of dry matter intake and the intake of plants is not always directed by the nutritive instinct. Forage offer, availability of each species and vegetative stage are also factors that determine the amounts intake by plants.