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Citation of this paper

Milk quality from Yak and Zom milk in Bhutan

J Wangdi

Renewable Natural Resources-Research and Development Centre (RNR-RDC), Jakar, Bumthang, Bhutan
jmewangdi@yahoo.com

Abstract

Milk composition has high importance in the making of dairy products. Information related to Yak milk compositions is limited,with very few attempts made to study it. The objective of this study was to report empirical information on the composition and quality of Yak milk in Bumthang, one of the Yak rearing districts of Bhutan, with the aim of using it as the basis for a more detailed investigation of Yak milk and on the development of a niche market for Yak dairy products in the country.

The average values in milk fromYak and Zom were 7.08 and 5.86 % fat, 10.6 and 10.4 % solids non-fat, 4.86 and 4.80% protein, 5.82 and 5.70% lactose, 0.81 and 0.84% other solids, freezing point of -0.724 and -0.697C and density of 1.34 and 1.033 kg/l, respectively. The average daily milk production was 1.09 kg for Yak and 1.61 kg for Zom.

Keywords: crosbreed, milk analyzer, Yak, Zom


Introduction

Yak milk plays a very important role in the daily life of pastoralists, locally known as Brokpas in -eastern and central-, Jobs in –western-, Dakpas, Merak and Sakteng in Tashigang district and Lakhaps in west-central region of Bhutan. The milk is the main source of protein for the household members of pastoralists. Fresh raw milk is seldom consumed. Almost all milk produced is processed into dairy products: butter, hard cheese - locally known as Chugo - and fermented cheese called Yidpa. Milk surplus is either sold or bartered for basic necessities within the village and nearby towns. Given the rugged geo-topographical terrain, harsh climatic conditions and difficult accessibility of the region, developing and promoting a high quality niche market for Yak dairy products will enhanceYak herders’ income. Prior to developing a niche for Yak dairy products it is necessary to establish the average composition and quality of Yaks milk. .Current information is limited, and very few attempts have been made to determine the compositional quality of Yaks milk in Bhutan. Therefore, the objective of this study was to establish the baseline information on the composition and quality of Yaks milk. Comparisons were made with milk from the Zom (crossbreed Yak Bos grunniens and Tibetan bull Bos taurus).


Materials and methods

Milk samples were collected between April and September from 56 Yaks and 10 Zom (F1 of Yak x cattle), from three Yak herds in Chumey and Ura block of Bumthang district. The females were of different age, lactation stage and parity number, although under similar management practices all year round. The three herds were located in the range of 2 hours walking distance from the human settlement areas, selected to make data collection easier. The samples consisted of 30 ml of milk collected from each animal. Milk samples were stored and transported in a cool box to be analysed. The analysis was done after 2 hrs from the collection, using automatic ultrasonic milk analyzer (Master Eco, India) at an average sample temperature of 22 degree Celsius. The milk analyzer used in this study has the capacity to measure the percentage of fat, solids non-fat, protein, lactose and other solids, as well as the percentage of added water, density and freezing point, in less than 2 minutes per sample. The daily milk yield of Yak and Zom were also recorded using a spring balance with 10g precision.The data were analyzed using descriptive statistics in SPSS, version 21 (George and Mallery 2014).

Figure 1. Yak (Bos grunniens).


Result and discussion

Average daily milk yield and milk composition

The Yak average daily milk yield was 1.09 kg (range from 0.3-2.3 kg) and 1.61 kg (0.88-3.0 kg) for the Zom, the latter being higher than the 1.41 kg/day, reported by Dorji (2000). The higher average daily milk yield of Zom could be attributed to the heterosis resulting from crossbreeding between Yak (Bos grunniens) and Tibetan bull (Bos taurus), figure 2; however, in contrast milk components were found lower in Zom milk as compared to the Yak’s milk. The herders in this study indicated that the Zom in general has longer lactation length and produces higher daily milk of lower density as compared to Yak. Correspondingly, the density of Zom milk (1.033 kg/l) recorded in this study, was found lower than the Yaks’ milk (1.034 kg/l). Joshi (1982) reported total milk yield of 720 kg in 180 days lactation for the Yak and 1300 to 1690 kg in 180 days lactation for the Chauri -cross of Yak (Bos grunniens) and local hill cow (Bos indicus) and vice versa.

Figure 2. Zom is the the cross of Tibetan bull (Bos taurus) with yak. Figure 3. The male is known as Zo, and it is reported to be
infertile and used for draft purpose.

Table 1. The daily milk yield and the compositional quality of Yak and Zom’s milk
Parameters Yak Zom
n 56 10
Daily milk yield, kg 1.09 0.05 1.61 0.21
% Fat 7.08 0.20 5.86 0.55
% Solids non fat 10.62 0.08 10.39 0.19
Density, kg/l 1.034 1.033
Freezing Point C -0.724 0.01 -0.697 0.02
% Protein 4.86 0.03 4.80 0.07
% Lactose 5.82 0.04 5.70 0.11
% Other solids 0.81 0.01 0.84 0.02
% Total solids 17.70 16.25

The fat content of Yak milk falls within the range of 5.5–7.5 % reported by Li et al (2009), although the upper limit was found much higher in this study.

The protein content of Yaks milk ranged from 4.40 to 5.1 %, about the same as reported by Li et al (2009) and Nikkhah (2011). This author reported 16.9 - 17.7% for total solids, 4.9 - 5.3% for protein, 5.5 - 7.2% for fat, 4.5 - 5.0% for lactose, and 0.8 - 0.9% for minerals.

Dong et al (2007) reported that the fat content varies around 6.5%, protein and lactose about 5.5% and ash 0.8% in Yak milk. They also reported that the Yak milk yield and their composition were affected by breed, age, parity and body condition of cow, pasture growth and quality, milking time, milking methods and environmental factors.

In this study the lactose content ranged from 5.2 to 6 %, higher than the 5% reported by Nikkhah (2011), and quite the same as in the report of Dong et al (2007).

The average total solids was 17.5 % for Yak milk, falling within the ranges 16.9–17.7 or 16.9 -17.7% reported by Li et al (2009) and Nikkhah (2011), respectively. The finding of 0.81% ash was comparable to that of 0.8 % reported by Dong et al (2007).


Conclusions


Acknowledgement

The author would like to acknowledge the herders for their support, particularly for providing the milk samples free of cost; Mr. DB Gurung, E A Chumey and Lhawang Dhendup (ex-Gup), Ura for arranging logistics for the collection of milk samples; and the staff and management of the RNR-RDC, Jakar.


References

Dong S, Long R and Kang M 2007 Milking performance of China Yak (Bos grunniens): A preliminary report. African Journal of Agricultural Research, Volume. 2 (3), pp. 52-57.

Dorji T 2000 Genotypic and phenotypic characterization of the Yak (Bos grunniens) and Yak farming systems in Bhutan. MSc. Thesis. Institute of Land and Food Resources, University of Melbourne, Australia.

George D and Mallery P 2014 IBM SPSS Statistics 21 Step by Step: A simple Guide and Reference, 13/E, Pearson Paper, 416 pp.

Joshi D D 1982 Yak and Chauri Husbandry in Nepal. Published by Mrs. Kaushalya Devi Joshi, Kathmandu, Nepal

Li H Ma Y, Dong A, Wang J Li Q, He S and Maubois J 2009 Protein composition of Yak milk Dairy Science Technology 90, pp. 111–117.

Nikkhah A 2011 Science of Camel and Yak Milks: Human Nutrition and Health Perspectives. Food and Nutrition Sciences, 2, pp. 667-673.


Received 19 September 2014; Accepted 20 December 2014; Published 1 January 2015

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