Milk and Dairy Products in Human Nutrition

Production, Composition and Health

Young W. Park, George F. W. Haenlein, Young W. Park, George F. W. Haenlein

• Publisher: Wiley-Blackwell
• Year: 2013
• Print ISBN: 9780470674185
• eBook ISBN: 9781118534205
• Edition: 1
• Topic: Technology & Engineering
• Subtopic: Food Science
• Index: Technology & Engineering

Milk is nature's most complete food, and dairy products are considered to be the most nutritious foods of all. The traditional view of the role of milk has been greatly expanded in recent years beyond the horizon of nutritional subsistence of infants: it is now recognized to be more than a source of nutrients for the healthy growth of children and nourishment of adult humans.

Alongside its major proteins (casein and whey), milk contains biologically active compounds, which have important physiological and biochemical functions and significant impacts upon human metabolism, nutrition and health. Many of these compounds have been proven to have beneficial effects on human nutrition and health.

This comprehensive reference is the first to address such a wide range of topics related to milk production and human health, including: mammary secretion, production, sanitation, quality standards and chemistry, as well as nutrition, milk allergies, lactose intolerance, and the bioactive and therapeutic compounds found in milk. In addition to cow's milk, the book also covers the milk of non-bovine dairy species which is of economic importance around the world.

The Editors have assembled a team of internationally renowned experts to contribute to this exhaustive volume which will be essential reading for dairy scientists, nutritionists, food scientists, allergy specialists and health professionals.

1

Production Systems around the World

Christian F. Gall

Centre for Agriculture in the Tropics and Subtropics, Institute for Animal Production, Hohenheim University, Stuttgart, Germany

Corresponding author: Email: [email protected]

1.1 ECOLOGICAL CONDITIONS

One can distinguish between temperate, subtropical, ­tropical dry, tropical humid and montane conditions, each offering different possibilities for milk production, and which are the basis for different production systems (Seré & Steinfeld, 1996).

The chief dairy zones are the lowlands of the temperate climatic zone (Table 1.1). Often these receive high rainfall, which is unfavourable for cropping and the land is best used as grassland. Less than 0.5 ha may carry an animal unit (AU). Similarly, land on high-altitude mountains, for example the Alps and Pyrenees in Europe, at 1500–2000 m above sea level, is not useful for cropping because of high precipitation and short vegetation period but is used as a welcome addition to grazing by dairy animals from valley farms with limited cultivable land.

The tropical environment is generally less suitable for high-producing European dairy animals, mainly because at elevated ambient temperatures the animal needs to expend energy for dissipating excess heat. Metabolic heat production is reduced by reducing feed intake and lowering ­metabolic rate, and this is not compatible with high milk production (Rhoads et al., 2009). As heat ­dissipation is mainly by water evaporation, high air ­humidity further aggravates the negative effects of the tropical environment. In addition, the humid tropics are not ­suitable for high-producing dairy animals because night temperatures mostly remain above 30°C and the metabolic heat cannot be dissipated (Preston & Leng, 1987).

Cattle of the Bos taurus genus are of little importance in the equatorial zone with extreme rainfall. Although ­vegetation may be abundant, with fast growth and early maturity, the plants have a high fibre content and consequently are difficult to digest and their nutrient value is low. Although increased use of the Amazonian basin for cattle-keeping demonstrates that a feed base can be created there, the preceding deforestation is not acceptable for ­ecological and socioeconomic reasons (Butler, 2011).

In tropical dry-lands, lack of forage due to insufficient rainfall is the limiting factor, in addition to elevated temperature. More than 400 mm rainfall is generally required to sustain cattle. In the humid savannah with 500–1000 mm rainfall, between 4 and 10 ha may be required to carry 1 AU, depending on the annual rainfall pattern. With higher and less variable rainfall only 2 ha may be required for 1 AU and only 0.5 ha on improved pasture. However, where rainfall is sufficient and feed supply is good, cattle-keeping competes with cropping for surface, capital and labour. Although average annual rainfall is not sufficient to determine the suitability of an area (because the availability of water for plant growth depends on the annual distribution pattern and the evaporation of water), it is a useful approximation. Where rainfall is extremely low and erratic, with regularly occurring extended drought periods, the feed base is insufficient to meet the nutrient requirements of ­cattle and more than 50 ha may be required to carry one tropical AU (De Leeuw & Tothill, 1990). Although ­conditions are less suitable in semi-arid and sub-humid tropical areas, much milk is produced here because of the preponderance of small-scale farmers who depend on it. In sub-humid Africa, milk production may be hampered by disease (e.g., trypanosomiasis) but disease-tolerant breeds can be kept even for milk production (Agyemang, 2005).

Table 1.1. Pasture area required to sustain livestock by ecological zones in the tropics.

Source: based on data from De Leeuw & Tothill (1990).

Ecological zone	ha/tropical AU*	Comment
Temperate lowlands	0.5	Grassland more suitable than cropping
Tropical highlands	0.5	Competition with intensive cropping
Tropical, humid	0.5–2	With improved pasture
Humid savannah	4–10
Subtropical, dry	>50

*Tropical AU = 250 kg liveweight.

Tropical highlands with temperate climatic conditions and sufficient rainfall may be ideal for cattle-keeping. Here, less than 0.5 ha may be required per AU and dairying is possible even with temperate breeds, although with a high density of human population and high soil fertility competition from cropping may leave little room for ­livestock, unless both operations are integrated.

1.2 SYSTEMS

1.2.1 Small-scale milk production

Very early in history, people must have learnt to milk. Certainly boys herding the flock tasted some milk directly from the udder and milk was extracted from the udder of animals which had lost their young. Later on, this will have developed systematically, for example by early slaughter of excess male progeny. Eventually, rearing of youngstock was combined with milking whatever quantity was possible without compromising the development of the young. The so-called dual-purpose system, where milk production is combined with rearing and even fattening of all male progeny, was the prevailing system in small-scale farming over the centuries and is still prevalent today in those areas where small farms dominate (Falvey & Chantalakhana, 1999).

In the past it was difficult to generate an adequate family income with agricultural activities alone on small farms (as prevails in many European countries) with limited ­production resources (land and capital) but possibly excess labour. Labour-intensive livestock keeping, dairy animals in particular, provided the possibility to generate additional income. Thus, dairying based mainly on pasture ­supplemented with agricultural by-products, was part of an integrated agricultural smallholder family enterprise in most countries. It is estimated that around 14% of the world’s population depend directly on dairy production for their livelihoods. In order to support smallholders in Europe with a view to the socioeconomic impact (on average, dairying accounts for about 20% of agricultural output in EU countries), milk production was heavily subsidised by ­market intervention (price support and milk quotas, see section 1.13). Similarly, in the USA the milk price was ­stabilised by subsidies, in Canada by milk quotas.

Even today, in the tropics and subtropics under rain-fed conditions, families living on a hectare or two cannot ­survive economically with crops alone. Livestock production on these farms, in addition to improving family ­nutrition, provides a higher return on farmers’ labour and land. Milk production allows cash to be earned daily, even with little equipment and inputs, for example a single dairy cow or some goats or a Zebu cow. Livestock also add security to the family enterprise. Even landless peasants may benefit from this opportunity. Furthermore, it is a source of organic material and soil nutrients generally lacking in such ­systems. Small-scale milk production of this nature can be successful with local resources (breeds, feeds, ­management). Women’s smallholder dairy development in East Africa illustrates the promise that a new livestock activity can offer to a farming system under economic stress (Owango et al., 1998). Whenever conditions are improving and milk ­production for the market is the aim, better-responding genotypes are required that contribute earlier maturity, ­better reproductive function during lactation, and better milkability. While some within-breed improvement through selection works well, this is a long-term effort and its sustainability under the prevailing ­conditions in developing countries is rarely ensured. In ­particular, the necessary ­programmes to maintain pure Zebu (Bos indicus) breeds and strains is critical for their survival, while imported European Bos taurus breeds are more attractive for ­crossbreeding for milk yield improvement.

Specialised milk production is economical only if about 3500 kg milk can be sold per cow yearly. In the tropics, this performance is generally not attained with forage alone. Also, milk replacers for calf rearing are generally not ­available (see section 1.9). Therefore, production systems with limited milk production (approximately 1500 kg of sold milk in 300 days) combined with rearing a calf per year by the cow (with forage and limited feed supplements) are preferred over specialised dairy and meat production (Preston & Leng, 1987).

The extent of the contribution to overall milk production by local and Bos indicus breeds is difficult to assess as breeds are not considered in dairy statistics of different countries. It used to be very high in Central and South American, Asian and African countries in the past, and it still will be in subsistence production systems. However, with increasing intensification and crossbreeding the contribution of local and pure Zebu breeds is diminishing.

1.2.2 Specialised milk production in large commercial dairies

During the 1950s and 1960s in industrialised countries, farms increasingly specialised. Farms with multiple activities tended to give up dairying as a sideline, while those continuing were becoming larger and taking advantage of economies of scale. Where optimal use of limited agricultural resources does not have to be considered, during the twentieth century dairying has developed into large ­specialised operations with highly productive dairy breeds, advanced technology and capital-intensive systems of ­production. Examples of technological innovations widely adopted by dairy farmers include (Laister et al., 1999; USDA, 2009):

• indoors feeding with high inputs and sophisticated feeding systems;
• elaborate animal housing;
• careful computer-assisted herd management including feeding, reproduction and health;
• modern, largely automated milking equipment in ­efficient milking parlours;
• on-farm refrigerated bulk milk tanks;
• mechanised waste-handling systems.

In these systems, Bos taurus cows may be milking up to 20 000 kg per lactation period of 305 days. Although investment in buildings and facilities, cost of feed procurement and herd management may be quite high, profitability is ensured by high production efficiency. As feed conversion is more efficient with milk production than with fattening, these farms do not consider rearing excess calves not needed for herd replacements, and they dispose of them as early as possible. Large dairy operations were established in some socialist countries: Russia, Poland, Bulgaria, Syria, Nicaragua, Cuba. Typically they comprised several units of about 100–500 milking cows each, with separate barns for calves, heifers, dry and milking cows, and ­milking parlours sometimes used around the clock. Other features included total mixed rations based on maize silage and alfalfa hay prepared and distributed with mobile ­mechanical feeders (Lammers et al., 2000). Similar operations can be found even in developing countries, where they supply the affluent market of the capital cities.

A minimum viable herd size is nowadays considered to be about 100 milking cows (Bos taurus). For instance, in the USA between 1997 and 2006 the proportion of herds with less than 100 cows decreased from 41% to 21%, whereas the proportion with more than 500 cows increased from 24 to 47% (USDA, 2008), and two-thirds of all milk was ­produced on farms with more than 100 cows in 2000 (Blayney, 2002). Some operations are huge, comprising several thousand cows. In 1998, the top 20 US dairies were ranked by Successful Farming Magazine (Looker, 1998). The smallest of these farms had 6500 cows and the largest 18 500. The ever-increasing number of large commercial enterprises benefit from economies of scale, but raise socio­economic concerns because they are not only ­crowding out small farmers, but also the agrarian and rural structure is changing (i.e. the disappearance of ancillary activities such as milk collection and artisan processing).

Recently, interest is growing in organic (biological, ecological) dairying. Regulations for official recognition differ between countries but typically stipulate the following in Europe (Borell & Sørensen, 2004; European Union, 2007b):

• half of the total feed intake, both grazing and barn feeding, must originate from the farm;
• no mineral fertilisers or pesticides may be used;
• the time period between drug administration and milking must be twice that of conventional production;
• parturient cows shall be in individual loose boxes;
• calves must receive non-processed natural milk for the first 10 weeks.

Although these practices and the produce appeal to consumers, there may be little advantage with regard to ­welfare, health and rep...

Table of contents

• Cover
• Title page
• Copyright page
• Contributors
• Preface
• 1 Production Systems around the World
• 2 Mammary Secretion and Lactation
• 3 Milking Procedures and Facilities
• 4 Milk Lipids
• 5 Milk Major and Minor Proteins, Polymorphisms and Non-protein Nitrogen*
• 6 Milk Protein Allergy
• 7 Milk Carbohydrates and Oligosaccharides
• 8 Milk Bioactive Proteins and Peptides
• 9 Milk Minerals, Trace Elements, and Macroelements
• 10 Vitamins in Milks
• 11 Milk Minor Constituents, Enzymes, Hormones, Growth Factors, and Organic Acids
• 12 Lactose Intolerance
• 13 Milk Quality Standards and Controls
• 14 Sanitary Procedures, Heat Treatments and Packaging
• 15 Sensory and Flavor Characteristics of Milk
• 16 Fermented Milk and Yogurt
• 17 Cheese Science and Technology
• 18 Butter, Ghee, and Cream Products
• 19 Condensed and Powdered Milk
• 20 Frozen Dairy Foods
• 21 Nutritional Formulae for Infants and Young Children
• 22 Whey and Whey Products
• 23 Goat Milk
• 24 Buffalo Milk
• 25 Sheep Milk
• 26 Camel Milk
• 27 Horse and Donkey Milk
• 28 Sow Milk
• 29 Yak Milk
• 30 Other Minor Species Milk (Reindeer, Caribou, Musk Ox, Llama, Alpaca, Moose, Elk, and Others)
• 31 Human Milk
• Supplemental Images
• Index