Freedom from Hunger, Thirst and Malnutrition
This Freedom covers the basic needs of animals to have access to suitable food and drinking water. However, it is based on the outcomes, that is the experiences that animals will have (hunger, thirst) and the physiological consequences that can occur (malnutrition) if this Freedom is not met, rather than giving a detailed guide to how animals should be fed. Often this Freedom, as with all others, is now supplemented with a required action or practice as well. Thus, this Freedom is often written as: Freedom from hunger, thirst and malnutrition - by ready access to water and a diet to maintain full health and vigour
a) Hunger: Hunger can occur when animals are unable to meet their dietary requirements for maintenance and growth from the food available to them in their environment in the following ways:
Grazing animals when there is insufficient forage to satisfy their requirements.
· In housed systems where animals are fed inadequate quantities of food.
· Deliberately, when animals may be knowingly fed less than requirements.
· Management factors, such as lack of knowledge about the specific dietary needs of an animal.
· Economic issues such that it is too expensive to feed all animals to requirements
· Inadequate trough or feeder space in confined animals, which can lead to competition and a reduced intake in subordinate animals.
· In breeding animals which are fed a low ration to prevent excessive growth and consequent health problems.
Example: Parent stock of meat chickens, or broiler breeders, have the same genetics for high rates of growth as the broiler chickens that will go on to become meat. However, if they are allowed to eat to appetite they will become excessively heavy, which will interfere with their ability to breed, and can cause lameness and metabolic disorders. These birds are kept on a very restrictive diet for much of their lives to prevent this fast growth. Although this feeding practice can reduce the incidence of health problems arising from becoming very heavy, this does mean that these birds are at risk of hunger for much of their lives.
b) Thirst: Thirst can occur when animals do not have access to sufficient fresh water to meet their needs in the following ways:
· In grazing or free ranging animals if natural water courses are not available, or are inaccessible, or if the water supply is contaminated in some way.
· During periods of drought there may be very low water availability, which can also affect forage growth such that the animals will experience both hunger and thirst simultaneously
· There may also be a mistaken belief that animals, such as sheep and goats, can meet their requirements for water from the plants that they eat, and so do not need to be provided with additional water. However, these animals do need to be given fresh water to drink, in addition to the water that they can obtain from grazing, and so a lack of knowledge can also contribute to this Freedom not being met.
· Thirst may also occur when animals are not provided with water in confined systems, or water provision is not sufficient to meet animal needs.
Example: Lactating animals have a very high requirement for water and may experience thirst when other animals would have sufficient water to meet their needs.
c) Malnutrition: Malnutrition can occur when animals are not provided with the right quality of food to meet their specific needs. This differs from hunger in that the animals may be able to eat a sufficient quantity of food to be satiated, but the quality of the food is insufficient. This may be, for example, because the diet is inadequate for protein, even if it contains sufficient carbohydrate or fat, or because important micronutrients or trace elements are not present. The requirements of animals can vary during different life stages, from the very rapid growth of young animals, to the specific needs of pregnant and lactating animals. Thus, malnutrition can occur due to lack of knowledge, as well as an inability to provide a diet of sufficient quality.
ASSESSMENT OF HUNGER
Hunger can be assessed scientifically using the following methods:
1) Simple weighing of animals
2) Body condition scoring system
3) Behaviour studies (e.g. Increased willingness to feed, feeding motivation, distance willing to travel to feed etc).
4) Physiological indictors
1) Simple Weighing of Animals
Hunger caused by long-term under-nutrition results in loss of bodyweight. Therefore, weighing animals regularly using a calibrated weigh-scale is one simple method of determining that an animal is not receiving sufficient feed. However, weighing animals is not always practiced on farms and inadequate nutrition can lead to slow growth. In some welfare assessment schemes, the age of piglets at weaning is used as an indicator of the quality of feeding on a farm.
2) Body Condition Scoring System
Long term hunger also causes a loss of body tissue and fat, or ‘body condition’. The regular assessment using a scoring system can allow a loss of body condition in animals to be detected. Body condition scoring systems have been developed for adult pigs, cattle, horses, goats and sheep. For some species, e.g. horses, this can be carried out by visual inspection. However, for species such as sheep the presence of a woolly fleece means that body condition scoring must be done by manual palpation of individual animals.
3) Behaviour Studies
In research settings, hunger can be assessed in a number of ways through animal behavioural studies. The experience of hunger can be expressed in an increased willingness to feed, but also to perform behaviours that will give access to feed. Thus, hunger can be assessed by giving an animal access to feed, and measuring the total amount of feed it consumes or the speed at which it eats. Feeding motivation can also be measured by requiring the animal to expend time or energy to gain access to feed. Studies have used long runways or passages to force animals to travel some distance to eat. The distance they are willing to travel, and the speed of movement can be used as indicators of hunger. In other studies, animals must push through past a weighted door or repeatedly press a button to gain access to feed. The maximum amount of weight tolerated, or button-presses made, is an indicator of feeding motivation.
4) Physiological Indictors
There are also physiological indictors of hunger. Body glucose levels are reduced in a hungry animal. Other indicators of hungers can be assessed from a blood sample. Beta hydroxybutyrate and non-esterified fatty acids are commonly used indicators, particularly in late pregnant animals where they can be used in management to prevent metabolic diseases.
ASSESSMENT OF THIRST
Lack of water causes dehydration. Dehydration causes a loss of fluid in the skin and it becomes less elastic. Thirst can be assessed scientifically using the following methods:
1) Skin tent test
2) Inspecting the mucous membranes
3) Behavioural test
4) Welfare Quality protocols
1) Skin Tent Test
Veterinarians commonly used the ‘skin tent’ test to detect dehydration in animals. The skin on the neck or thorax of the animal is pinched between the thumb and forefinger and then released. In animals in a normal state of hydration, the skin moves back to its normal position almost immediately. The longer the skin takes to return to normal, the more dehydrated the animal is.
2) Inspecting the Mucous Membranes
Inspecting the mucous membranes (gums and inside the nostrils) is another method of detecting dehydration. These areas should be moist. The eyes of a dehydrated animal may also appear sunken into the eye sockets.
3) Behavioural Test
By the time the animal shows a positive response to the ‘skin tent’ test, or shows dry mucous membranes or sunken eyes, it is quite dehydrated and may require veterinary intervention. However, there are currently few reliable measures available that are more sensitive to lower levels of dehydration. A study in Belgium and Brazil showed that broiler chickens deprived of water for 12 hours drank more after the deprivation period than non-deprived animals. The experiment was repeated with a comparison of 0 and 6 hours. Only birds in Brazil showed more drinking after 6 hours deprivation, while the birds in Belgium did not, suggesting that high ambient temperatures play a role in the motivation to drink.
4) Welfare Quality Protocols
Because of this lack of a sensitive test, most welfare assessment protocols assess the quantity or space allowance of the drinkers available relative to the number of animals, and the water flow rate and the cleanliness of the water. For instance the Welfare Quality protocols that cover, pigs, dairy and beef cattle, and poultry, considers the cleanliness of the water and the functionality of the drinkers. For cattle, the flow rate is also assessed.
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