**1.1 Global production of sheep's milk**

The constant population growth and the increase in the demand for dairy products and their derivatives have generated a continuous increase in the world per capita consumption of milk, which reached 111.3 kg in 2015, and an increase of 12.5% is estimated by 2025 [1]. However, there are significant regional disparities among developing countries, where fresh dairy products remain, by a large margin, the most consumed, unlike in developed countries where consumer preferences

**Figure 1.** 

*Per capita consumption of processed and fresh dairy products. OECD-FAO, 2016 (adapted from [2]).* 

incline toward processed products (butter, cheese, skimmed milk powder and whole milk powder) (**Figure 1**) [2].

The world production of milk of all species has followed an upward trend in recent decades, reaching in 2015 approximately 818 million t [1]. The highest percentage of dairy production is derived from the dairy industry (82.6%), followed by buffaloes (13.9%), goats (1.9%), sheep (1.3%), and finally, camels, which contribute only 0.3% of the total [2] (**Figure 2**).

The dairy industry is markedly regionalized and is associated with a long tradition of production and consumption of dairy products, mainly cheeses. The world production of fresh sheep's milk registered in 2016 by FAO estimates 10,366,980 t. This is mainly produced in the Asian region (44.6%), which houses the two main producing countries: China (1,361,360 t) and Turkey (929,432 t). In the European continent (32.7%), Greece (711,577 t) and Romania (631,419 t) stand out, ranking as the third and fifth largest producers of sheep's milk, respectively. The African

**Figure 2.**  *World milk production by species. FAO 2016 [2].* 

*Production, Processing, Commercialization and Analysis of Costumer Preferences of Sheep… DOI: http://dx.doi.org/10.5772/intechopen.83806* 

**Figure 3.**  *Geographical distribution of sheep's milk production. FAO 2016 [3].* 

continent produces almost a quarter of the international sheep milk inventory (21.8%), with subsistence production systems; countries such as Syria (651,867 t), Mali (529,373 t) and Sudan (403,008 t) are among the top 10 producing countries worldwide. The American continent has a relatively minimal participation in the world production of sheep's milk (0.9%); only the following countries provide official productivity data: Mexico (57,589 t), Bolivia (29,617 t) and Ecuador (3617 t) (**Figure 3**) [3].

 Sheep's milk production in the North American countries is not significant; it is estimated that Mexico, the United States and Canada have approximately 200 production units dedicated exclusively to the production of milk, with less than 10,000 sheep each [3, 4]. Data from associations of producers estimate that in 2010, there were 20 production units with the potential to milk sheep with an approximate inventory of 6000 animals distributed in the states of Coahuila, Guanajuato, State of Mexico, Puebla, Querétaro and Veracruz (**Table 1**). In 2009, Querétaro was the state that presented the highest production, with 30,000 liters. Likewise, in this state, the first association of dairy sheep called "Producers of Milk and Derivatives of Sheep S.A. of C.V." united 13 producers and integrated the collective brand "Del Rebaño" [5].

 In Chile, the sheep cheese market, unlike that for goat cheeses, is very underdeveloped, given the low national consumption tradition and the low consumer culture regarding this product. However, in the country, there are foreign colonies of immigrants from Mediterranean countries that have favored the expansion of these products. In 1995, the first exploratory imports of sheep's milk cheese were carried out, with a volume of 1.25 t, and a positive evolution was observed, which was manifested the following year with an increase to 3.88 t. In 1998, the total national supply in the sheep cheese market reached 7.2 t, of which two were of national origin and the rest imported mainly from Spain and France. Currently, the national demand is less than 6 t per year, a figure that represents a volume of milk of less than 40,000 liters. The national production of sheep's milk associated with its industrialization and cheese making is estimated between 20,500


### **Table 1.**

*Some units of sheep milk production in Mexico [8, 16].* 

 and 22,000 liters per year, equivalent to between 3 and 4 t of cheese [6]. In 2014, the *El PASO* location assessed five regions that produce most of the country's cheeses: Los Ríos (49,394 t), Los Lagos (30,939 t), La Araucanía (6202 t), Biobío (906) and Metropolitana de Santiago (273 t) [7].

In Chile, two sheep dairy breeds have been introduced: Milchschaf and Latxa, which have been fostered through the crossing of dairy males with sheep from Chilean cattle ranchers, with the aim of reducing the initial investment costs. The dairy breed of the male or the genetic improvement program that is chosen will basically depend on three aspects: forage potential, adaptation of the dairy breed that is being introduced to the area, and the reproductive and productive characteristics of each one [8]. Within the dairy production and ovine cheese industry, a highlight is the initiative developed by the University of Magallanes in the city of Puerto Natales (Chilean Patagonia) that produces the southernmost cheese of Chile [9].

### **1.2 Sheep's milk: physicochemical characteristics and nutritional properties**

 Recent studies have determined that the chemical composition of milk varies depending on the feeding of the sheep, modifying the percentages of fat, protein, lactose and the fatty acid profile of the milk depending on the ratio of forage to concentrate in the diet or of the supplementation with protected fat. The results show that diets with the highest forage content (>40% DM) have a significantly lower milk yield (0.8 g/kg), but with a higher fat content (0.32 g) and concentration of conjugated linoleic acid (CLA) (2.28 mg/kg). The addition of protected fat in the rumen in the diets has a positive effect on the concentration of fat (0.22 g/100 g) and CLA (3.98 mg/g) in milk, but the protein concentration is reduced (*P* < 0.001). On the other hand, diets with a higher proportion of concentrate (>40% DM) affect the biodegradation processes and the synthesis of CLA (**Table 2**) [10].

The particular characteristics in the chemical composition of sheep's milk, mainly in relation to its high levels of total solids and protein, make it especially suitable for transformation into yogurt and cheese. About 95% of sheep's milk is converted into dairy products, which also acquire a regional connotation of origin and quality [11, 12]. For this reason, when we refer to the quality of sheep's milk, we must concentrate mainly on its ability to be transformed into high-quality dairy products, generate high yields of these products per liter of milk and ensure the safety of these foods [11]. In this way, three types of "quality" can be distinguished when analyzing products of animal origin: hygienic and sanitary quality, dietetic and nutritional quality and gustatory and gastronomic quality [12].

The unique characteristics of sheep's milk have been discussed in extensive reviews of literature [11–15], in which the quality of sheep's milk is evaluated in terms of its technological and coagulation properties. High concentrations of


*Production, Processing, Commercialization and Analysis of Costumer Preferences of Sheep… DOI: http://dx.doi.org/10.5772/intechopen.83806* 

1 *mg/g of methylated fatty acids; F, forage based rations; C, concentrate based ration; S, protected fat supplemented rations; U, unsupplemented fat protected rations.* 

### **Table 2.**

*Descriptive statistics of data used in forage:concentrate ratio and protected fat supplementation meta-analysis [10].* 

protein, fat and total solids in milk are associated with high yields in the production of dairy products; therefore, the aforementioned studies conclude that sheep's milk has higher yields compared to goat's milk and cow's milk because of its superior chemical composition (**Table 3**) [13].

Milk proteins include caseins and whey proteins; caseins are a family of phosphoproteins synthesized in the mammary gland in response to lactogenic hormones [17], which represent the highest protein share of sheep's milk (76–83%) [18]. The heterogeneity of the caseins is determined mainly by the presence of genetic variants; four genetic variants of caseins are recognized: αs1-CN, αs2-CN, β-CN and κ-CN. Sheep's milk has higher concentrations of the four casein variants compared to sheep and goat milk [17]. Whey proteins represent 17–22% of the total protein content; 75% of whey proteins are albumins (α-lactoalbumin and β-lactoglobulin), with a high content of the AA phenotype of β-lactoglobulin, which has been shown to provide greater efficiency in the manufacture of sheep cheese [19, 20].

In recent decades, there has been an increase in interest in foods with specific nutritional properties. The nutritional advantages of sheep's milk over other species does not derive from its content of protein, minerals or vitamins; the superiority as a functional food lies in its lipid content, more specifically in its fatty acid profile; ovine products have received direct attention due to the possibility of being enriched with fatty acids' potential benefits to health, especially vaccenic acid (VA, C18: 1 t11), c9, t11CLA, also


*NNP, non-protein nitrogen. <sup>1</sup> Retinol. <sup>2</sup> Tocopherol. <sup>3</sup> Thiamine. <sup>4</sup> Riboflavin. <sup>5</sup> Niacin. <sup>6</sup> Pantothenic acid. <sup>7</sup> Pyridoxine. 8 Biotin. <sup>9</sup> Folic acid. 10Cobalamin.* 

### **Table 3.**

*Comparison of the chemical composition of different species (adapted from [13, 18, 22]).* 

called rumenic acid, and α-linolenic acid (ALA, C18: 3, n3). Sheep's milk, compared to cow's milk, contains three to four times the amount of VA and CLA c9T11 [15].

The milk of small ruminants and their derivatives are the largest source of CLA in human food [21]. The content of CLA in ruminant milk decreases in the following order: sheep > cow > goat, with contents 1.08, 1.01 and 0.65%, respectively [22]. However, the particular management conditions of sheep herds determine seasonal oscillations in CLA concentrations due to the variability in the availability and quality of forage [23].

*Production, Processing, Commercialization and Analysis of Costumer Preferences of Sheep… DOI: http://dx.doi.org/10.5772/intechopen.83806* 
