Importing exotic cows which performed poorly under local conditions
In 2017, over 5000 young pregnant cows ( heifers) imported from Australia and New Zealand, were sold to some farmers. They were assured that a cow would yield 20 litres/day. Within a few months, the farmers’ expectations started to shatter when the cows failed to produce the promised milk yields. Currently, farmers are facing financial ruin as a consequence of several grave issues with the cows they purchased: Poor milk yields, very low conception rate, abortions, stillbirths, high mortality rates, and unrecognised diseases.
This article is an attempt to examine the reasons for the poor performance of imported cows under local conditions.
The dairy cow is a biological milk- producing plant which converts nutrients, derived from a variety of dietary constituents, into a nutritious product. The quantity and quality of milk governed by factors such as cow’s genetic makeup, quality of feed, management practices and surrounding environmental conditions.
The imported cows were a crossbred between Holston Friesian (HF) and Jersey. The high milk producing capability of HF and Jersey’s ability to tolerate high-temperature conditions could be the reasons the authorities selected such a crossbreed. Since past information of the animals was not divulged, it is not possible to state much about the history of these heifers.
Assuming that the heifers have the required genetic potential to produce higher milk quantities, let’s examine whether factors such as poor quality of feed, bad management practices or unfavourable environmental conditions caused these disturbing issues.
Quality of feed
Some authorities have alleged that farmers fed cows with a poor quality feed which triggered the issues with the animals. According to the farmers, at the start animals were fed with a recommended feed mixture. However, once they noticed the cows were not economical some started to feed them with locally available fodder.
The digestibility rate of high fibrous grass such as matured ‘Gini’ is quite low and it can generate a high level of body heat during the digestion process. Such a situation can adversely affect the milk production capabilities of a cow.
If the poor quality feed is the cause, one has to query how government- owned National Livestock Board (NLDB) farms failed to obtain expected milk yields from imported cows. Those farms are managed by experienced managers and veterinary surgeons.
According to the Auditor General’s 2018 report, the average milk yield per cow in 2016, at three upcountry NLDB farms were around 11- 15 litres/ day. At Ridiyagama NLDB farm this was about 11 litres/per cow/day.
Impact of local environmental condition on imported heifers
Globally, many studies have been conducted on environmental stress on cattle. Although Sri Lanka has collected climatic data for over a century it is rather unfortunate that no attempt was made to use this information in animal sciences.
Climatic factors such as ambient temperature, relative humidity (R/H), wind, rainfall, and radiant temperature can negatively affect the cows’ performances. The influence of environmental impact on animals is complex and it is not possible to isolate a single factor to explain the stress on an animal. We have to recognise what cow senses is a combination of all surrounding environmental factors.
Environmental stresses in cattle could result in loss of appetite, cessation of feeding, lethargy, increase respiration and heart rates, immobility, aimless wandering, staggering, flow of saliva outside the mouth, open mouth breath, and the collapse of the animal, non-responsiveness, and seizures. Further, these conditions can cause reduction of milk yield, reduce weight gain, shorter gestations, abortions, calves with reduced body weight, reduction of the quality of colostrum (mother’s first milk after the calf is born), development of unproductive udders, sick and weak calves, higher mortalities among calves and drop in conception rate.
Our farmers too noticed such symptoms among their animals. Let’s examine whether these issues initiated due to unfavourable environmental conditions.
Comfort (Thermo Neutral) zone
During the milk-producing process, higher amounts of internal heat are generated, especially among high yielding cows. When environmental conditions are favourable, the animal has the ability to dissipate this heat without using her stored energy. The temperature range that the animal doesn’t have to expend stored energy to maintain normal body temperature is called its comfort zone or thermo neutral zone. For healthy cattle, this temperature is between -15 and 22 degrees Celsius.
When the cow is exposed to conditions beyond the comfort zone, it starts to utilize stored energy to dissipate its own internal body heat. At this stage, the cow reduces its feed intake followed by a reduction in milk yield.
Prone to diseases
Due to environmental stress, the animals’ immune system can also be weakened and become very susceptible to various bacterial, viral and physiological diseases.
Impact on the development of udders
During pregnancy, the cow utilises her stored energy to form the mammary glands. When environmental conditions are not favourable, the stored energy is utilised to overcome the stresses. Eventually, this will negatively affect the morphology of her mammary glands. In such situations, udders can become dried, underdeveloped and unproductive.
Reproduction issues
Under an environmental stress situation, cow’s expression of heat (estrus) signs and also the duration and intensity of estrus expression can be dramatically weakened. Without such signs, farmers are unable to detect estrus signs. This will cause a sharp drop in the success rate of artificial insemination.
Embryo death and effect on the fetus
Embryos of the cows are highly vulnerable for heat stresses during the first 17 days of conception. At this phase, a protein that resists heat stress is not formed. This situation can be fatal to the embryos.
Development of follicles can also be retarded due to heat stress. This could result in weakening of signals to indicate that she is pregnant. In the absence of such signals from the embryo, a cow can stop secreting the needed hormones to maintain the pregnancy. Finally, this can cause the death of embryos.
Calves born under heat stress
Due to environmental stresses, placental development of the cow can be negatively regulated. The placenta is an organ that develops in the cow’s uterus during pregnancy aiming to provide oxygen and nutrients to the growing fetus.
Environmentally stressed cows normally have a shorter gestation length and give birth to lighter calves by about 5 kg. Calves of such cows will have a reduced efficiency to absorb antibodies (immunoglobulin) from colostrum (first milk) and could be easily infected with diseases. Malformation, growth retardation and higher mortality rates can also be observed among those calves.
Stresses due to transportation
Imported cattle were transported from ports in poorly ventilated lorries that were not designed to carry the live animal. Cattle transport produces physical and psychological stresses among animals. Stress may result in altered metabolism, immune competence, and behaviour, as well as failure in reproduction. Further, it can reduce milk production.
Comparison of Australian and local climatic conditions
The average R/H and temperature of Victoria province of Australia ( the source of heifers) was compared with a few locations in Sri Lanka such as Nuwara Eliya, Hambantota, Badulla, Kurunegala, and Vavuniya. It was revealed that R/ H in Victoria is around 60 per cent while in Sri Lanka locations R/H is around 80 per cent. The temperature in Victoria was higher than that in Nuwara Eliya from November to March.
The heifers that rose under the Australian low humid environment during their first 3- 4 years were later exposed to high humid tropical Sri Lankan conditions. Has the impact of environmental changes together with the transportation stress caused the above-mentioned issues to the imported cows?
Impact of Relative Humidity on milk yield
It is interesting to observe how cows with European blood perform under various humid conditions. Daily average milk yield per cow in a farm which this writer visited at the Californian desert town called Barstow, US is 30 litres/day. Within a year R/H varies from 14-66 per cent and it rains only about 24 days. The milk yields drop on rainy days due to rising humidity.
An Israel cow produces the highest quantity of milk in the world. In 2017 the average milk yield of a cow was more than 33 litres/ day. The humidity in this zone from MarchDecember is around 45-60 per cent. During summer months the temperature could go above 300 C.
There are many countries where cows with European blood have been successfully raised in low humid high-temperature regions. We do not have such low humid zones in Sri Lanka.
After visiting a farm in Israel or Australia one could easily come to the conclusion that cows with European blood can be raised in high-temperature zones. Was this a reason the authorities selected Ridiyagama at Hambantota district to raise exotic cows without considering the existing high R/H conditions?
Misting animals as a measure to relieve heat stress has been done at Ridiyagama. This operation tends to increase the surrounding R/H in humid areas. Direct wetting of the animal’s body should be practiced in such zones.
The distribution of imported heifers directly to the farmers was a grave mistake. These heifers should have been raised in government farms and only distributed the offspring. Studies found that the calves born under unfavourable climatic conditions have the ability to better cope with acute environmental stresses in the future.
The existence of different climatic zones in Sri Lanka has been completely ignored when imported cows were distributed.
Sri Lanka should introduce a long- term feasible strategy to become self-sufficient in dairy milk. Improving the genetic potential is just a single measure that should be implemented with several other essential factors. In order to achieve this, we should concurrently implement tasks such as reintroducing higher import tax for powdered milk, improve the local powdered milk industry, infrastructural developments, assistance to dairy farmers (loans, grants), development of farmer organizations (cooperatives, etc), farmer training and research, selection of breeds based on climatic zones, production of extra professionals such as veterinarian/agriculturists, grassland development and feed management, dairy marketing, processing and quality control, and dairy waste management.