Dairy production, milk quality and milk somatic cell count on smallholder farms

in Hochiminh City, Vietnam

Nguyen The Thao
 

Department of Animal Husbandry and Veterinary Sciences,
Angiang University, Angiang Province, Vietnam

  ntthao@agu.edu.vn

 Small-holder dairy cattle production systems 

All countries in tropical Asia are economically classified as developing countries, where most dairy production is derived from smallholder farmers. Smallholder dairy production systems are potentially very important and can be generally classified as (1) specialized dairy farms and (2) mixed animal-crop farming systems or integrated farming systems (Chantalakhana and Skunmun, 2002).

According to Devendra (2001), one important feature of these systems is their rapid expansion in smallholder areas, driven essentially by the urban demand and the opportunities to generate income. The ownership of between 2-15 animals and milk production is a major component, accounting for about 35-65% of total farm income. The smallholder dairy production systems are very common in peri-urban areas, where good market and production services exist. However, there are several constraints to production in these systems, which include: inadequate feed resources and feeding systems, breeds and breeding, animal health care and lack of organized marketing and market outlets.       

As in other Asia countries, almost all the dairy cattle in Vietnam are owned by small-scale farming households. Dairy farmers in Vietnam normally own a small number of cows (usually less than ten animals). It is estimated that 70% of them own 3 to 5, 25% own 10 to 15, and only 5% own more than 50 dairy cattle.  More than 70% of the population is distributed in the South and surrounding areas of Hochiminh City, where good markets and production services are found (MARD, 2002).

History of dairy cattle production in Hochiminh City 

Prior to 1975- the year of Vietnam’s reunification - a dairy cow program was started in South Vietnam with the raising of breeding cows in the cool climate province of Lamdong (at Ductrong State Farm) and of dairy cows in the peri-urban areas of Saigon (Hochiminh City). At that time dairy cattle production was small, and only around 30 households had around 200 crossbred Indian or Indian-Jersey milking cows. Milk production was limited (the yield was 3-6 litres/cow/day) and delivered directly in bottles to restaurants and rich people living in the city (Hiep, 1973, cited by Man, 1995).

For almost ten years (1975 to 1985), the national dairy program focused mainly on the development of state production. Small scale private production was nearly stopped, because of the shrinkage of the fresh milk market after the war, lack of milk collecting points and fewer customers (consuming fresh milk is one indication of higher class in the new regime: Man, 1995)

The milk industry however has resurged since 1986 as a result of Doi Moi, Vietnam’s economic reforms. During this period, high milk-yield breeding programs were introduced in the area in two stages. The first was to produce improved native breeds by cross-breeding between Red Sindhi and Local Yellow cattle, and the second by a Holsteinization program, to produce F1, F2 or F3 crossbred Holsteins. Along with extension, training, veterinary support, insemination and AI services received increasing support from the government. Vinamilk, the biggest Vietnamese milk processing company, quickly improved and set up a milk collecting-point network. Consequently, the population and distribution of dairy cattle and milk production increased quickly in the period 1990-1994, with an average increase per year of 26.7%. The total number and total milk production in 1994 were 10,400 head and 30,000 tons, respectively (Cuong, 1994, cited by Man, 1995).  

In 1995, Foremost, a foreign company, became Vinamilk’s major competitor. Foremost has brought in a more competitive market to dairy producers. The more competitive environment, as well as the governmental technical assistance programs and improved knowledge and experience of the dairy farmers, created consequently a more dynamic and booming dairy industry, specifically in Hochiminh City (Tam, 2004). The number of dairy cows has increased more than five times in the last ten years (Table 1).

By 2005, the total number of dairy cows in Hochiminh City was 56,162 head, and the number of cows in lactation was 27,092 head, making up 54% and 58% of the total national population, respectively. Average milk yield was around 4900 kg/cow/ lactation) and milk production was 129,000 tons / year. Almost all dairy production in Hochiminh City was based on small households. Statistical data in 2005 showed that there were 8,728 dairy farms in the city, of which 49 % of households kept under 5 head, 33.5% from 5 to fewer than 10 cows, 14% from 10 to fewer than 20, and only 2.65% of households kept more than 20 head (DARDH, 2006).  

The concentration of dairy cows in Hochiminh City (54% of the national population) is not surprising for several reasons: (1) high population, with more than 6 million people; (2) relatively high per capita income; (3) most research institutes and processing factories are located in Hochiminh City; and (4) the efficiency of the city’s government support (Tam, 2004).

Factors affecting dairy production in Hochiminh City

Environmental temperature

Environmental temperature, radiant energy, relative humidity and wind speed contribute to the degree of heat stress. Incorporation of the effect of ambient temperature and relative humidity gives the temperature-humidity index (THI). THI is calculated by using the formula: THI = temperature [dry bulb] + (0.36 x temperature [wet bulb]) + 0.42 (Hahn and McQuigg, 1967 cited by Malin, 2002). THI that affect dairy cattle can be classified into values of up to 74 as normal, values 75-78 as alert, values 79-83 as danger and values of more than 84 as emergency (USDC-ESSA, 1970). Ravagnolo et al. (2000) reported that THI was the most critical variable to quantify heat stress, and consequently feed intake and milk yield decreased. This author also concluded that milk yield declined by 0.2 kg per unit increase in THI when THI exceeded 72. Other researchers estimated that milk yield was reduced by 0.32 kg per unit increase in THI (Ingraham, 1979). Malin (2002) estimated that median milk decline in Vietnam as a result of high THI was 7kg/day.

Heat stress is also a major contributing factor to low fertility in lactating dairy cows in hot climates. Progesterone secretion is lower, oocyte quality and embryo development becomes poorer and there is increased embryo mortality, possibly even resulting in termination of pregnancy. However, there are more than just the immediate effects; heat stress may also have delayed effects (Wofenson et al., 2000), such as greater susceptibility to disease because of a weaker immune system (Bertoni, 1998).    

Urbanization

Hochiminh City has contributed a great deal to the economic development of the country. The city is connected with Dongnai, Baria-Vungtau and Binhduong provinces to form a focal economic hub. It has also cooperated with the Mekong Delta provinces, the rice basket of the country, the South-Western provinces and the Central Highlands, with forestry potential, and the Central and Northern provinces. Hochiminh City is one of the country’s biggest venues to attract foreign direct investment.

However, there is a clear trend towards urbanization in the surrounding areas of Hochiminh City to support the development of service and manufacturing industries. The value of land has increased and as a consequence most agricultural land has been sold for building houses and factories. Dairy cattle are concentrated into smaller areas within the built-up zones, sharing housing with family members (Khang, 1999). Agricultural land is rapidly decreasing, pasture land is shrinking and feeds such as agricultural by-products and grasses are becoming more scarce.

Breeds and breeding

The local cattle of Vietnam have small body size, and low meat and milk production abilities. However, the improved-local cattle breeds play an important role for dairy breeding as well as dairy development programs in Vietnam. The dairy breeding program in Vietnam is mainly by AI from the selection of females of basic breeds (improved local cattle bred from Red Sindhi and Yellow cattle), with Holstein- Friesian frozen semen, in order to combine the attribute of tropical adaptation and superior milk and reproductive performance.

In general, according to Chantalakhana and Skunmun (2002), dairy Holstein- Friesian (HF) crossbreeds are well suited to local feeding, management systems, are adapted to the hot-humid tropical climatic conditions, and easily produce 15 kg milk per day or higher, and are accepted by the farmers. The authors also mentioned that the optimum level of the HF gene in crossbreds depends on many other factors besides genetic ones, such as farmer experience, availability of veterinary services, milk price, and other socio-economic factors. In many countries, crossbreds of 50% to 75% HF gene appear to be optimum, while some farmers in these countries who have extensive experience in dairy feeding and management are able to raise cows with a higher level of HF, such as 87.25% or above.     

At present, the population of crossbred dairy cattle (female local cattle crossed with Red Sindhi and Holstein-Friesian bulls) is almost 90% of the total dairy population, and the rest is pure Holstein-Friesian (Do and Hoang, 2001). There are 3 levels of the percentages of HF inheritance: F1, 50%; F2, 75%; and F3, with 87.5% HF. The breeding program is mainly by artificial insemination, using Holstein- Friesian frozen semen from the Moncada center (Vietnamese buffalo and cattle frozen semen center), and imported from New Zealand, Holland, Australia etc. (DARDH, 2006).  

In a recent study, it was found that there were very few F1 cows, and the F3 and F4 generations were most popular. The farmers explain that the F1 generation was really good in adapting to the local conditions, but because of low milk production most farmers only bought the F1 and/or F2 to establish their farms, and after calving, the female calves, with a higher proportion of HF blood, were used for replacement of milking cows or to expand the herds.

Although the F3, F4 and above generations’ milk production can meet the demand of the dairy producers, these generations require better feeding and care, and under local conditions, these  needs can not be satisfied. The problems, consequently, are that the cost of milk production increases and reproductive failures become more common.

Feed and feeding management

Feeding and nutrition have repeatedly been highlighted as the major constraint in animal production systems globally (ILRI, 1995) and also sub-regionally in South East Asia (Devendra et al., 1997). The significance of improved nutrition in dairy production is therefore a major consideration. This is especially important, because in intensive systems, the feeding cost accounts for about 40-60 % of the total cost of milk production. In smallholder systems, inadequate land and size of operation further constrain production (Devendra, 2001).

The Southeastern region, including Hochiminh City, where feeds for dairy cattle can come from green fodder (native and cultivated grass, legume forages etc.), crop residues, agro-industrial by-products and concentrate (Cuong et al., 1992 cited by Man, 2001; Khang, 1999). In Paper 1, the results of the survey show that the main sources of feed are native grasses, Napier grass, rice straw, cassava waste, brewery by-product and commercial concentrates. Most farmers have to buy these feeds from the market or from their neighbors, including even grasses and rice straw, and this leads to costly production.

Feeding management needs to be considered in dairy production to promote efficiency in feed resource use, and associated with this, increased productivity from the animal, and clear evidence for this has been presented by many researchers. Leng (2005) stated that as THI increases above 72 animal body temperatures and breathing rate increased and consequently feed intake and milk yield decreased. Underfeeding causes low milk production, especially in early lactation, excessive body weight loss, lower conception rate, and more herd health problems and less income over feed cost. While feeding above normal nutritional standards results in an increase in milk yield, feeding high amounts of concentrate, with low roughage, causes milk fat depression. In contrast, feeding high levels of roughage can result in lower milk yield (Schmidt and Van Velck, 1974).

Small farmers in practice ration feed based on the milk yield and their experience, which could lead to better production efficiency.

Consumption and marketing of dairy products

Arguably, market demand for milk and the ability of farmers to earn an attractive return from the sale of dairy products are the greatest stimuli for expansion of the dairy sector. Demand for dairy products is related to income, and hence the collection, processing and distribution system is largely organized to supply urban consumers, who have greater purchasing power than rural communities (Reynolds et al., 1996). The availability of a market pull, organized marketing and access to market outlets are important prerequisites for the distribution and sale of the milk produced. In the absence of these, prospects for promoting efficient milk production will always be vulnerable and at risk (Devendra, 2001).

Milk and milk products do not belong to the traditional diet in Vietnam. However, in urban centers the demand for dairy products is increasing. In order to improve milk production, the marketing system, especially, milk collection systems could be a major consideration.

Currently, consumption of milk products has shown strong increase. Vietnam has not managed to raise dairy production fast enough to meet the national demand and depend on imported dairy products (Table 3).

Most of the milk produced in Hochiminh City is sold by contract to 48 and 33 collection points of the two biggest processing companies – Vinamilk and Dutch Lady (Foremost), respectively. Less than 8% of the total milk is processed by small factories and by producers themselves and fed to the calf or other animals (Fig. 1). The collection point networks have reached the rural areas within and around Hochiminh City, as most dairy farms are located in more remote areas (Tam, 2004).

Figure 1: Milk purchase by companies (Source: Tam 2004)

The milk price has a strong impact on dairy farmers’ incomes and dairy production. In general, however, the fresh milk price in Vietnam is still lower than in other countries in the region (Thailand 0.29 USD and Taiwan 0.55 USD per litre) and is approximately 0.24 USD per kg.  However, the price ratio of 1 kg of concentrate to 1 kg of fresh milk is higher in Vietnam (70.0%), followed by Thailand (56.5%) and Taiwan (42.7%) (DARDH, 2006).   

Animal health care and veterinary services

Improving animal health care is also essential, as disease is a serious source of loss. Diseases often rank as the most important constraint to production. A variety of diseases affect the calves and the milking cows, and in the smallholder farms the situation is more serious because of inadequate use of medicines and access to appropriate corrective measures and resources (Devendra, 2001).

Vietnam has had a national veterinary system for along time, concerned mainly with veterinary services, animal quarantine, vaccination and slaughterhouse inspection. There are actually two separate systems at present: one includes the Veterinary Department in MARD and six subordinate regional centers (each cover an average of 10 provinces), and the other includes provincial and district veterinary stations which are funded by and responsible only to provincial governments. At the commune level, animal health services are provided by 3 - 4 person teams which are appointed by the People’s Committee. They do not receive a salary but work as private providers of veterinary services.  However, in the dairy sector, there are very few veterinarians who have good skills in disease treatment or artificial insemination. Thus the effectiveness of the veterinaries services is very low (DARDH, 2006).

Sub-clinical mastitis as a cause of dairy production losses

Mastitis is the body’s defense against an injury to the udder tissue (Emanuleson and Philipsson, 1984; Kaneene and Hurd, 1990; Miller and Dorn, 1990; Heringstad et al, 1997). The injury activates an inflammatory response in the udder. Actual mastitis is characterized by hot, painful and swollen quarter or mammary glands and is frequently accompanied by fever and loss of appetite. Mastitis always causes a certain destruction of milk producing tissue which leads to a decrease in milk production and on physical inspection the milk my contain flakes, clots, shreds or blood (Akers, 2002). High clinical mastitis results in high cost for treatment and high culling rate (Valde et al., 2004)  

Sub-clinical mastitis is one of many forms of mastitis and is the most prevalent, with 15 to 40 sub-clinical cases for every mastitis event, and normally occurs before the other forms that lead to clinical mastitis (Akers, 2002). Gianneechini et al. (2002) reported that sub-clinical mastitis is a condition in which there is no detectable inflammatory change in the udder and no observable abnormalities in the milk. During sub-clinical mastitis, the milk is usually visibly normal, but the concentration of milk somatic cell count (SCC) is increased, or pathogens are identified from milk samples processed for bacteriological testing. The reduction in milk production attributed to sub-clinical mastitis may account for 70%–80% of the total losses (Philpot and Nickerson, 1991, cited by Gianneechini et al., 2002).

Milk somatic cell count (SCC)

The somatic cell count of raw milk is the most common producer related method to evaluate milk quality and udder health status of the lactating cow.  Leucocytes and a small percentage of epithelial cells normally occur in milk. This combination of cells is referred to as the milk somatic cell count. The term “somatic”, which means body, alludes to the fact these are normal body derived cells. These leucocytes enter the milk as a consequence of homing to the mammary gland from the bloodstream in response to chemicals released directly by bacteria cells or materials released by the injured mammary gland. Therefore, an increase in milk SCC is closely correlated to an occurrence of intra-mammary infection (Akers, 2002). This author also found that milk from uninfected cows typically contain less than 200,000 cell per milliliter and it is not uncommon to find uninfected cows with milk SCC of 50,000 or less. Milk samples with values greater than 400,000 cells per milliliter are very likely from cows with inflammation, probably caused by mastitis producing organisms (Akers 2002). Similarity, Schalm et al. (1971), classified the SCC (number of somatic cell) in healthy cows as “normal” (up to 200,000 cells/ml milk), from 150,000 to 500,000 cells/ml milk is “slightly positive”, from 400,000 to 1,500,000 cells/ml milk “positive”, 800,000 to 5 million cells/ml milk “very positive”, and more than 5 million cells is “extremely positive”. Milk SCC is required for good quality milk by some countries. The EU, New Zealand, and Australia require that milk used for dairy products must have under 400,000 cells/ ml, Canada < 500,000 cells/ml and the USA < 750,000 cells/ ml (Sargenant et al., 1998; Norman et al., 2000 and Van Schaik et al., 2002). In the present study the milk SCC in dairy cattle in Hochiminh City was significant higher and the values are presented in Paper II.

Factors affecting milk somatic cell count in dairy cattle

Environmental factors

Stresses of various types have been implicated as causing increases in SCC. Somatic cell counts are generally lowest during the winter and highest during the summer (Dohoo and Meek, 1982, cited by Harmon, 1994). Smith et al. (1985) showed that rate of infection with environmental pathogens was highest during the summer and coincided with highest number of bacteria in bedding. They suggested that the stress of high temperatures and humidity could have increased the susceptibility to infection as well as increased the numbers of pathogens to which cows were exposed. Heeshen (1975 cited by Phat, 1999), Saloniemi (1995) and Xuan (2005) recommended that good ventilation could reduce the contamination of the pathogens and the cows. In Paper II, the THI values were above 82, a danger level for dairy cattle that could have contributed to the high of SCC in dairy cattle in the site studied.

Herd size

Harmon (1994) found that herd size did not affect milk SCC. However, Normal et al. (2000) in a survey in the USA found that the larger herds generally had lower milk SCC than smaller herds, that supported the premise that mastitis management is better in larger herds than in smaller herds. In contrast, Xuan (2005) reported that at small household level, a dairy with a smaller size it may be easier to take care of the cows, and maintain a clean, hygienic and well-ventilated environment. Thus the cows were healthier and it was possible to prevent the infection of microorganisms in the mammary glands. John (1998) suggested that it is also important to consider how disease spreads between cows. Disease may spread by direct contact between cattle, spread by fluids or secretions such as blood, milk or manure. Disease may also spread by breathing air containing infectious organisms and it may spread by contact with items that have been in contact with cows (milking machines, water, feed and other equipment). The most obvious means of spread for contagious mastitis is by organism-laden milk from infected cows carried to another cow during the milking process. It might be carried by the milking machine, milker's hand or common use of a towels or rags. In Paper II there was a trend of higher milk SCC with higher herd size, but no significant difference was found.

Genetic factors

The relationship between the variation in SCC that occurs with the level of HF blood in dairy cows has been widely investigated, for example by Philipsson, et al. (1995), Phat, (1999), Xuan, (2005), Coffey et al. (1986) and Emanuelson et al. (1988) (Cited by Philipsson et al., 1995), who reported that the heritability of SCC is higher than that of clinical mastitis, and the genetic correlation between mastitis and SCC was shown to be reasonably high, 0.6-0.8. Phillipson et al. (1995) found that there were no significant differences in the level of HF blood proportions in Swedish Friesian bulls and SCC in the daughters, but the trend of milk SCC increasing with decreasing HF blood levels was confirmed. However in tropical conditions, in cows with lower exotic blood levels, the adaptation to local conditions could be better, and therefore higher heat stress tolerance and diseases resistance capacity. Xuan (2005) found that, in dairy cows, a higher percentage of HF blood was accompanied by higher milk SCC, which was also found in Paper II.    

Age of the cow

Generally, SCC increases with advancing age and number of parities. This can be explained by the fact that the risk of infection increases with age (perhaps because the immune system in an older cow is not as efficient). Moreover, in the older cow, excessive degradation of the fibers of the medial suspensor ligament can reduce its support capacity so that the udder becomes pendulous irrespective of time relative to milking and can lead to difficulty with milking as well as problems with teat injury and increase mastitis risk (Akers, 2002).  Tainturier (1997) pointed that in the older cow, because the elasticity of the teat orbicuslaris is less efficient, it take a long time to close the teat canal. Consequently, this increases the infection of microorganisms in to the udder and increases the SCC in milk (Eberhart et al. (1982) cited by Harmon, 1994). These authors surveyed 3130 cows and found that the mean SCC by cow age (from 2 years up to more than 7 years) was ranging from 232,000 to 868,000. Valde et al. (2004) also suggested that in a cow population with a high culling rate the cows will be younger and less susceptible to mastitis, and this may in turn lead to a lower incidence rate. In Paper II, because of the limited time of the study, some farmers could not remember how old their cows were, but knew their parity number, and obviously a cow with a higher parity number will be older. 

Milking practices

The hands of a milking person can become contaminated with mastitis-causing pathogens, either from handling dirty equipment or from contact with contaminated milk from infected cows. Some microorganisms prefer living and growing on skin, whether it is the cow’s teat skin or the milker’s hands. From the hand, bacteria pass through the teat duct and multiply in milk-producing tissues. Microorganisms breach the teat duct in several ways. Between milkings, microorganisms may pass through the teat duct by multiplying inside the duct, or by physical movement resulting from pressure placed on the teat end as the cow moves about. During milking, microorganisms may be propelled into or through the teat duct into the teat cistern (Aker, 2002). On the other hand, during milking, by mistake, the teat may be injured by the milker. In the site studied, it was found that 44% of dairy farmers hired labourers for milking (Paper I), with one labourer responsible for 3 to 4 farms. The study question was: would the milking labuorers have an effect SCC. The results presented in Paper II do not show any clear answers with respect to this question.

Lactation stage

Östensson (1993), working with dairy cattle, reported that SCC did not change significantly but tended to increase as lactation proceeded. Wilson et al. (1971) in dual-purpose cows found that the SCC was significantly influenced by lactation stage, reporting, as in dairy cattle, that SCC tended to be the highest early in lactation, declined, and then increased appreciably at the end of lactation. Another study in beef cows also found that early and late lactation animals were more frequently associated with high cell counts than animals in mid-lactation (Hunter and Jeffrey, 1975). However, Laevens et al. (1997) reported no effect of stage of lactation on SCC in dairy cows.

A partial explanation for this variation could be the milk yield of the cow during lactation, as Emanuelson and Funke (1991) and Miller et al. (1993) found a ”dilution effect” due to an inverse relationship between milk yield and milk SCC. In these studies it was assumed that a dilution effect caused the regression of milk yield on milk SCC. Miller et al. (1993) suggested that the observed negative relationship between milk yield and SCC may partly reflect both the true biological effects of udder inflammation and a dilution effect. Östensson (1993) mentioned that the milk somatic cell counts increase towards the end of lactation because of the higher prevalence of mastitis, normal involution of the udder and decreased milk production, which causes less dilution of the milk leucocytes.

Conclusions

·        Dairy production is a new component of small households in peri- urban Hochiminh City, and makes a very important contribution to national milk production supply.

·        Most dairy farmers practice intensive systems based on cut-and-carry systems, but with industrial by-products and commercial concentrate, which results in high feed cost.

·        Milk yields and milk composition were acceptable.

·        The main constraints are urbanization, high feed costs, low milk price and low fertility.

·        The average milk somatic cell counts and prevalence of sub-clinical mastitis in dairy cows are rather high.

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