Feature

Talking to the Animals

We can't ask animals how they're feeling, but new techniques do offer a chance to communicate with them.

Dr Christian John Cook

Ours is not a perfect world. If it were, there would be an abundance of parking spaces on rainy days and the supermarket checkout lines we chose would always move the fastest. This worldly imperfection also pervades the lives of our agricultural animals.

The imposition of stress upon livestock can severely affect an animal's production ability, including its resistance to disease -- ever noticed how quickly you get a cold when you are stressed? -- and its reproductive ability. Stress can also affect the final product quality, be it meat or milk. Unnecessary animal stress is also a welfare issue and this needs examination from both a humane and ethical perspective and from the potential of welfare issues as non tariff trade barriers.

Understanding, and reducing, animal stress also promotes an agricultural sustainability. New Zealand obviously has limited renewable resources. Unnecessary animal stress is a drain on those resources and if removed, those resources are then available for additional production gains. The nett result of this is an improved output (animal productivity) from the same input (resources) in a manner (removal of stress) that promotes environmental preservation.

Obtaining an understanding of animal stress is not easy. They cannot tell us verbally their concerns about their own discomfort and as, is the case for humans, animals are also very individual in what is or isn't a stressor.

While laboratory-based studies of stress are extremely important in providing base information they do also impose certain limitations. The close confinement of the animal, the handling from, and proximity of, human experimenters, and the unnaturalness of the setting, can all impose additional stress on the animal confounding the experimental stress we may wish to study. Research funded by the Foundation for Research, Science and Technology and the Meat Research and Development Council may help answer some of the questions.

Stress Studies in Freely Behaving Animals

The aim of our group is to study the animal in its natural setting while it is freely behaving with other members of its flock or herd and/or undergoing normal farm handling activities.

To do this we have developed a small backpack that sits on an animal's back and collects data from numerous micromeasuring devices on the animal and then transmits this data to a remote receiver that relays this data into a computer for analysis. This can all be done in real time which allows the experimenter to observe the animal's behaviour and physiology and, at any point, change the situation (for instance, introduce a dog) and immediately see any changes that occur.

The micromeasuring devices themselves are extremely small and the animals seem to "forget" very quickly that they are there and tolerate them extremely well, for long periods.

This technology has opened up the ability to measure stress changes not only in the body but also in the brain of freely behaving animals.

The Brain and Stress

Perception of, response to and, ultimately, control of stress all originates within the brain. It is the brain that coordinates and controls all the body's actions (cardiovascular changes, body temperature changes, hormonal changes etc) including behaviour. The ability to monitor what is happening in the brain represents a major leap in stress physiology and in animal welfare implications.

The mammalian brain does most of its communicating using chemical substances called neurotransmitters. The probes that we use, which are no larger than a dressmaker's pin, eavesdrop on this communication. From this "spying" we have seen a number of important changes occurring in communication with the imposition of stress and during normal social interactions. In particular, four types of neurotransmitters -- glutamate, gamma amino-4-butyric acid, 5-hydroxytryptamine and opioid-like peptides (such as endorphins) -- seem very important.

The relative contribution of each of these neurotransmitters is important in determining how successfully an animal copes with a stress, be it imposed by humans or by nature, and this differs with individual animals.

This type of profile, considered along with information on physiological changes within the body and behaviour, allow us to start ranking stressors for individual animals and then approaching how to modify them.

Not all stressors can realistically be removed from an animal's life, but if we understand how the animal's system can positively adapt to stress, we may be able to train it do so. Indeed, recently, we have found that animals that are given an interesting and playful environment, full of things to explore, when they are young show much more positive adaptations to stress when they are adults. This seems to be due to the selection of neurotransmitters they utilise in response to stress.

Other Microprobe Uses

This work also has other implications. Traditionally, various blood components are measured in animals during stress. This involves cannulation of blood vessels which can be cumbersome, involves taking blood from the animal, and may pose risk to the animal. With further microminiaturisation and development of our probes, we may be able to implant and seal them into blood vessels allowing measurement of blood factors without the need to remove a blood sample.

The probes can allow data concerning the animal's body temperature, cardiovascular system function, rumination and activity to be transmitted to a remote receiver.

The probes are adaptable to allow the delivery of a very small drug sample to a specific area to see the effects of blocking or stimulating a particular system's or neurotransmitter's response and its contribution to stress control. Often the response in the body to a neurotransmitter or other chemical release during stress is dependent upon the availability of receptor sites which are the receivers of the message. These receivers or receptor sites can also change with stress and contribute to the overall response and how an animal learns to adapt. By adapting and using a number of probes simultaneously we can also monitor this receptor function.

A further non-stress use of the probes that we are also pursing is in the area of feral species population control. Regardless of the mechanism (poison, toxin, immunoreproductive suppressant etc) chosen to control these populations, there is a great need to be able to selectively attract a target species (such as a possum) while repelling a non-targeted species (such as a native bird). We are using the probes to examine brain mechanisms of attraction and repulsion with the aim of finding substances that will selectively attract feral species to the population control mechanism while actively warding off nontarget species.

In Hugh Lofting's Dr Doolittle books, humans were enchanted by the possibility of talking to the animals. In charting the oceans of their brains we may not be able to talk to them, but perhaps we can at last understand what they are saying.

Dr Cook works for MIRINZ in Hamilton.