| Livestock Research for Rural Development 34 (4) 2022 | LRRD Search | LRRD Misssion | Guide for preparation of papers | LRRD Newsletter | Citation of this paper |
In recent years, several studies around the world revealed a number of therapeutic virtues of dromedary milk (Camelus dromedarius), which have contributed to its high demand. To meet this demand, a new type of breeding has recently emerged to increase camel productivity and to facilitate the marketing of the milk, the semi-intensive (semi-stable) system, through the introduction of food supplements. In this context, this study was conducted on dromedary milk collected from two breeding systems, extensive and semi-intensive, to determine the influence of camel feeding practices on the nutritional and mineral composition of the collected milk. Biochemical and mineral analyses were carried out with 3 replicates on milk samples from Sahrawi camels reared in Southeastern Algeria (10 samples from extensive breeding and 10 samples from semi-intensive breeding), each sample being a mixture of the same amount of milk from 4 to 5 camels. The results obtained showed that only pH, total protein, casein and total nitrogen (g/L) were significantly higher in semi-intensive milk than in extensive milk (6.54; 33.1; 23.5 and 5.99 vs 6.40; 28.7; 19.3 and 5.25, respectively). However, the values were comparable for mineral contents in milk from both systems. This study shows that camel feeding in semi-intensive systems does not have a negative influence on the biochemical and mineral composition of milk.
Key words: Algeria, Camelus dromedarius, feeding, milk composition, nutritional values
Milk is a source of minerals, proteins, lipids and vitamins essential for the human body. Compared to the milk of other ruminants, camel milk is nutrient rich and has scientifically proven therapeutic properties. It contains more proteins, vitamins (such as A, E, B2 and C) and minerals (such as potassium, calcium, iron, magnesium, copper and zinc), but less fat and lactose than cow's milk (Konuspayeva et al 2009, Al-Humaid et al 2010, Yoganandi et al 2015).
Camel milk is considered a complete source of nutrition for nomads in the extensive system. The camel's diet is based exclusively on rangeland plants, characterized by the low availability of fodder and water points. The dromedary, thanks to its particular feeding behavior, remains the only livestock species able to valorize the scarce nutritive resource into various products (Chehma et al 2008, Faye 2011).
Indeed, in recent years, camel breeding has begun to be oriented towards intensification, particularly for the production and marketing of milk. Following the example of other countries (Tunisia, United Arab Emirates and Sudan), the intensification of dairy camel breeding has started to develop in Algeria. Lactating camels are kept in pens near roads to make them accessible to milk buyers (Bedda et al 2019).
However, the feeding of camels in this new breeding system is based much more on the use of supplementary feeding in stalls than on natural rangeland feeding. In this context, this study aims to determine the impact of feeding dairy camels on the biochemical and mineral composition of camel milk from two camel breeding systems: extensive and semi-intensive.
Samples of fresh milk were collected from camels of the Sahrawi population in Ouargla region, Southeastern Algeria. Ten (10) samples were obtained from camels kept in extensive breeding. Their feeding is based only on natural desert grazing plants such as Anabasis articulata (Baguel), Traganum nudatum (Damrane), Ephedra alata (Alanda), Retama raetam (Rtem), Limoniastrum guyonianum (Zeiîta), Stipagrostis pungens (Drinn), Calligonum azel (L’azale) and Corulaca monacantha (Hadd). Ten (10) others were obtained from the camels led in semi-intensive breeding. These camels are allowed to graze in the morning in the natural pastures near the stable from 20 to 30 km and in the evening on their return to the stable, they receive fodder and concentrated feed such as wheat straw, alfalfa, barley and wheat bran (2 to 3 kg/camel/d). The watering of the herds in semi-intensive breeding is daily. On the other hand, in extensive breeding system the herds are watered every 7 to 10 days.
In both types of breeding, the breeders practice only one milking per day in the morning. Each sample represents the milk of a mixture of the same amount (500 mL) from four to five healthy female camels at the same stage of lactation.
For each breeding system milk, physicochemical and biochemical measurements were carried out. pH, density, and titratable acidity of milk were carried out according to the AOAC standard methods (AOAC 2016). Dry matter content was determined by drying 5 mL of milk in an air oven at 105 °C (IDF 21B 1987).
Ash content was determined by mass loss after incinerating 5 mL of milk in a furnace at 550 °C during 6 h (NF V04-208 1989). Fat content was determined by acid-butyrometric method (Gerber method) (Ling 1963). The total nitrogen content (TN) of milk, non-casein nitrogen (NCN) and non-protein nitrogen (NPN) fractions was determined by the Kjeldahl method (ISO 8968-1:2001) using a conversion factor of 6.38. Lactose content in milk was carried out using a lactoscan (Ultrasonic milk analyzer, SL 30, India).
The calcium content was determined by titrimetric method (ISO 12081:2010). The contents of potassium, sodium, magnesium, iron and zinc were measured by atomic absorption spectrometry (air-acetylene flame) according to the protocol of Adrian et al (1980).
Results were presented as the mean and standard deviation of three replicates of each parameter on 10 samples for each breeding system. Data processing of the physicochemical, biochemical and mineral analyses of milk was carried out by one-way statistical analysis of variance (ANOVA). All statistical analyses were performed using SPSS (Statistical Package for Social Sciences, v 26) software. P-values less than 0.05 were considered statistically significant.
The results of physical parameters of camel milk collected from both rearing systems, extensive and semi-intensive, are given in Table 1. The values shown are the averages of three replicates for ten samples from each system.
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Table 1. Comparison of physical parameters of camel milk collected from two breeding systems |
|||||
|
Parametres |
Extensive |
Semi-intensive |
SEM |
p-value |
|
|
pH |
6.40a |
6.54b |
0.03 |
0.019 |
|
|
Acidity |
16.3 |
16.9 |
0.20 |
0.135 |
|
|
Density |
1.028 |
1.028 |
0.00 |
0.311 |
|
|
DM g/l |
107 |
108 |
2.76 |
0.815 |
|
|
Ashes g/l |
7.66 |
7.24 |
0.36 |
0.579 |
|
| a, b In the same line, numbers followed by different letters are significantly different at the 5% level (p˂ 0.05);DM : Dry matter | |||||
For physical parameters, a significant difference (P ˂ 0.05) was recorded for pH values. pH was higher in the milk collected from semi-intensive rearing than in the milk collected from extensive rearing (6.54 ± 0.12 vs 6.40 ± 0.09, respectively). No significant difference was recorded for titratable acidity, density, DM, and ash contents in the two types of milk (p ≥ 0.05).
The results of the biochemical components of camel milk collected from the two farming systems are given in Table 2.
The obtained results revealed that lactose content was not significantly different between the milk samples collected from the two breeding systems. Furthermore, fat content was not significantly different (p ≥ 0.05). Fat content slightly increased in the milk samples collected from the extensive farming as shown in Table 2.
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Table 2. Biochemical composition of camel milk collected from extensive and semi-intensive breeding systems (g/L) |
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|
Parameters |
Extensive |
Semi-intensive |
SEM |
p-value |
|
|
Fat |
32.8 |
29.9 |
1.0 |
0.144 |
|
|
Protein |
28.7a |
33.1b |
1.1 |
0.035 |
|
|
Lactose |
37.3 |
35.6 |
0.8 |
0.326 |
|
|
Caseins |
19.3a |
23.5b |
0.9 |
0.020 |
|
|
Whey proteins |
9.43 |
9.63 |
0.31 |
0.761 |
|
|
TN |
5.25a |
5.99b |
0.17 |
0.028 |
|
|
NPN |
0.75 |
0.81 |
0.02 |
0.095 |
|
|
NCN |
2.23 |
2.31 |
0.05 |
0.421 |
|
|
a, b In the same line, numbers followed by different letters are significantly different at the 5% level (p ˂ 0.05). NPN: Non Protein Nitrogen ; NCN : Non Caseinic Nitrogen ; TN : Total Nitrogen |
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However, a significant difference was recorded for the average total protein, casein and total nitrogen contents (p < 0.05). Milk of the semi-intensive reared females was richer in total protein and casein than milk of the extensive reared females with 33.1 g/L vs 28.7 g/L and 23.5 g/L vs 19.3 g/L , respectively. It can be seen that the feed has an influence on protein concentration, especially on casein content in the milk.
Overall, statistical analyses did not show a significant difference (p ≥ 0.05) for the concentration of mineral elements in camel milk collected from the two farming systems. The calcium content was about 769 mg/L and 835 mg/L, respectively for the camels milk collected from extensive and semi-intensive systems. The magnesium content was about 25.6 mg/L of milk from camels reared on the range, and about 49.7 mg/L of milk from camels reared in semi-intensive farming. The content of sodium and potassium in milk collected from extensive breeding was about 692 mg/L and 1242 mg/L respectively, and for milk collected from semi-intensive breeding was about 853 mg/L and 1011 mg/L, respectively.
In contrast to trace elements, camel milk is characterized by a highest concentration of iron. Indeed, iron content averaged 4.51 mg/L for the extensive milk and 2.72 mg/L for the semi-intensive milk. Iron content was slightly higher in the milk collected from the extensive system than in the milk collected from the semi-intensive system (Table 3). In addition, zinc content of the milks analyzed was about 4.95 mg/L for the milk from the extensive farm, and about 4.82 mg/L for the milk from the semi-intensive farm.
|
Table 3. Average mineral contents of camel milk collected from extensive and semi-intensive farming (mg/L) |
|||||
|
Parameters |
Extensive |
semi-intensive |
SEM |
p-value |
|
|
Calcium |
769 |
835 |
76 |
0.686 |
|
|
Magnesium |
25.6 |
49.7 |
7.1 |
0.077 |
|
|
Sodium |
692 |
853 |
50 |
0.110 |
|
|
Potassium |
1242 |
1011 |
119 |
0.389 |
|
|
Iron |
4.51 |
2.72 |
0.70 |
0.238 |
|
|
Zinc |
4.95 |
4.82 |
0.70 |
0.938 |
|
The evaluation of the composition of camel milk after breeding intensification plays an important role in determining its dietary quality. In our study, the physicochemical characteristics of milk collected from two different breeding systems, indicated that only the pH was influenced by the breeding system. pH remains a very important index to determine the state of freshness of milk. It plays a major role in the transformation of milk into by-products and determines the quality of the final product (Abbas et al 2013). According to Yagil (1985), camel milk is slightly more acid than human milk (7.0) or bovine milk (6.6). This may be due to the high concentration of volatile fatty acids and to the relatively high vitamin C content of camel milk (Haddadin et al 2008).
In contrast, the density values of camel milk samples conducted under both systems were similar. The density of milk depends directly on the dry matter content, which is strongly related to the frequency of watering of the animal (Rahli et al 2013).
Furthermore, the results presented in Table 1 do not show a significant difference for dry matter content in milk from the two systems. Generally, the total dry matter content in camel milk is lower than that of buffalo milk (147 g/L) (Khaskheli et al 2005) and cow's milk (126 g/L) (Boudjenah-Haroun 2012).
Sutton (1989) reported that the high level of feed supplements for stall-feeding of camels as well as water intake directly affected the protein content of milk. Data on protein contents of camel milk collected from different farming systems confirmed that milk collected from semi-intensive to intensive farming is richer in protein than milk collected from extensive farming (Shuiep et al 2014, Fguiri et al 2018, Ayadi et al 2019). The high casein content in semi-intensive rearing milk is directly correlated with the high protein content in milk collected from this rearing. In general, the total casein content is lower in camel milk than in cow milk. Indeed, it represents 75-79% of the protein content compared to 77-82% for cow’s milk (Mehaia 1987, Ramet 2001).
However, in this study the lactose and fat contents were not affected by feeding practice. The lactose content of camel milk can vary according to the state of hydration; El-Hatmi et al (2003) indicated that the availability of water for the camel increases the lactose content in milk. On the other hand, in our study, the fat content of milk was about 32.8 g/L for milk collected from extensive system and 29.9 g/L for milk collected from semi-intensive system. These values are lower than those reported by Fguiri et al (2018) who reported that fat content is significantly higher in milk collected from extensive farming compared to that collected from semi-intensive farming. Shuiep et al (2008) demonstrated that the supplementation with energy concentrates decreased the fat content of milk.
Overall, the data on mineral content in camel milk are scarce. It has been assumed that fluctuations in mineral levels are due to differences in diet, breed, water consumption and analytical procedures (Haddadin et al 2008).
Milk remains the main source of dietary calcium. Calcium content decreases with dehydration and seasonal variation (Konuspayeva 2007).
Camel milk is known to be rich in iron compared to milk from other species. It could be a better alternative to human milk for infants, due to the fact that the majority of iron in camel milk is in the fraction easily accessible for intestinal absorption (Al-Awadi and Srikumar 2001, Aludatt et al 2010). The iron values of camel milk samples recorded in this study averaged 4.51 mg/L for extensive and 2.72 mg/L for semi-intensive milk. These values were higher than those reported by Aludatt et al (2010) and Al Haj and Al Kanhal (2010) in Jordan as well as those reported by Boudjenah-Haroun (2012) in Algeria. These results suggest that there was a wide variation in the iron concentration of camel milk collected from different locations. However, the feeding systems did not affect the iron content of camel milk.
Nevertheless, the collected milk seemed less rich in magnesium compared to the higher levels reported by Boudjenah-Haroun (2012), of 107 - 111 mg/L. According to Bengoumi et al (1994), the variations in milk magnesium levels, which act as an activator of several enzymes, are mainly related to dietary intake of this element.
However, the content of sodium and potassium were similar to those reported by Aludatt et al (2010). The variations in Na and K content can be attributed to the effects of seasonal heat, water consumption, feeding system and stage of lactation (Sboui et al 2009, Aludatt et al 2010).
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