Animal welfare has become an important feature in animal production since the onset of intensive breeding farms. Beside rising humanitarian concern, the well-being of the animal is important both for economic and environmental health reasons. In fact, poor animal welfare results in a loss of productivity, both concerning reproductive and growth rates, and an increasing need to use antibiotics and other treatments. Recent studies indicate that to breed animals in condition that consider animal welfare may be also cost effective for producers. Research has developed important tools to monitor animal health and welfare, and have identified many issues in the breeding system that can be fixed. Producing animal-derived food in a humane way is possible and affordable.
We have to raise awareness to this fact in both farmers and consumers to promote the best farming conditions. Achieving sustainability involves ecological, economic, and ethical responsibility, and thus lead us to consider animals because animal management has an impact on many other issues, such as hunger, poverty, disease control, and environmental protection.
The ethical mandate expressed by Mahatma Gandhi, “the greatness of a nation and its moral progress can be judged by the way its animals are treated” and the complementary ecological and economic imperatives are increasingly recognized and emphasized by the Food and Agriculture Organization of the United Nations. The welfare of humans and the welfare of animals are closely linked. In many regions, a secure supply of food for people depends on the health and productivity of animals, and these in turn depend on the care and nutrition that animals receive. Many diseases of humans are derived from animals, and the prevention of these animal diseases is important for safeguarding human health.
Roughly one billion people– including many of the world’s poor– depend directly on animals for income, societal status, and security, as well as food and clothing. And the welfare of their animals is essential for their livelihood. Moreover, positive relations with animals are an important source of comfort, social contact, and cultural identification for many people. Stress and welfare are words widely used and they have developed a range of meanings. The terms tend to be used in order to avoid being too specific about the nature of practical difficulties. Many of the issues surrounding these difficulties are receiving increasing public and scientific attention because of their societal and ethical implications. A stressing event is a situation in which the animal homeostasis is challenged.
It may be due to changes in a physical situation, high or low temperature, or societal change, addition of animals in a group, removal of the puppies. The animal will engage both behavioral and physiological responses to restore its homeostatic condition. Those two responses may take place simultaneously. For instance, to contrast an increase in environmental temperature, animals may seek for shades, behavioral response, while increasing their respiratory rate and sweating, physiological response.
Similarly, the introduction in a new group may cause the need to find a hiding place, to escape from the aggression of the leading animal, behavioral response, as well as an increase in the activity of sympathetic nervous system, and of the hypothalamic pituitary adrenal axis, resulting in an increase of corticosteroid blood levels, physiological response. The occurrence of sporadic stressor events are easily managed by the animal. Those events have no negative effects and may even allow the animal to increase its capability of adaptation. However, the persistence of stressing conditions impairs the animal well-being in many ways. HPA axis activation requires an increase of energetic expenditure, which is detrimental for the animal growth rate.
Moreover, HPA stress axis, a hypothalamic level, is strictly related to hypothalamic pituitary gonadal axis, which regulates reproductive features. Finally, it may result in increased susceptibility to infective diseases.
Animal welfare is defined by the five freedoms– from hunger and thirst, by ready access to fresh water and a diet to maintain full health and vigor; from discomfort, by providing an appropriate environment, including shelter and comfortable resting area; from pain, injury, and disease, by prevention through rapid diagnosis and treatment; to express normal behavior, by providing sufficient space, proper facilities and company of the animal’s own kind; from fear and distress, by insuring conditions and treatment which avoid mental suffering. All these freedom are achieved by the correct organization and management of the farm. European legislation and academia are working on defining the adequate breeding conditions for each species of zootechnic interest.
In fact, we have to consider that different species may react differently on the same condition. And what is detrimental for one may not be perceived as negative for another, depending on their innate behaviors. Each animal species has its own requirements for the five freedoms. For instance, social species, cattle or horses, should be housed with many co-specifics, while chickens should be in small groups of females with only one male, since the presence of many co-specific lead to aggressions. Beside some practical issues, as some of the ones that have been adopted resulted difficult to be enforced practically in some countries, we have to consider that each housing condition may have pros and cons.
For instance, although they have more freedom to move and express their behaviors, free-range laying hens are at higher risk of bone fractures, and the chance of colliding is higher in more open systems. On the other hand, battery caged hens have reduced freedom of movement, but also lower risk of infections since they are separated from their excrements. In some cases, the optimal conditions are the result of a mediation from different needs. The consequences of the aggressive behaviors may be limited by mutilations, such as beak trimming in hens or tail docking in pigs. However, this treatment has an impact on animal welfare and may not avoid aggression. In addition, genetic selection have changed the optimal breeding conditions for a species.
In fact, different strains of animals may more susceptible than others to specific breeding requirements. For instance, some strains of rabbits have higher anxiety rates and thus are not comfortable in areas which allow them to perform exploratory behaviors. Moreover, the breeding requirements may change according to the sex, age, and life stage of the animal. In many species– as in chicken– adult males cannot be kept in groups unless they are siblings. Farrowing sows have to be kept in small crates, which limits their movement but avoids damage to the piglets. Also age, sex, and stage specific feeds have been implemented in order to consider the different metabolic needs of the animal at the different productive stages.
This way, along with avoiding to have energetic deficits in stages which are particularly demanding, it is possible to insure adequate nutritional supplies to developing animals, leading to a correct development of their hypothalamic system. Futhermore the correct management of the animal during their early life is also a key factor to enable the correct development of the HPA axis, and decrease abnormal anxiety like and aggressive behaviors in adult animals.
Animal welfare may be measured by both a direct approach, involving measures on biological samples from animals and an indirect approach, which focuses on farming conditions, possibly of co-specific societal relationships, possibility of displaying the behavioral response, or the adequate pavimentacion. European entities have regulated many aspects of animal breeding and are continuing to put effort in researching the optimal breeding conditions for each species. Examples of direct approaches are measuring specific behaviors of the animal, as stereotypies, which are behaviors that have not practical function. And that are repeated invariably in response of an uneasy situation or the impossibility of expressing the appropriate behavior.
For example, broiler breeder chickens, which are fed a limited diet to avoid excessive weight gain, adopt stereotypies of picking even in the absence of food. Pigs kept in small crates may spend a lot of time bar biting. Corticosteroid levels are among the most used parameters to evaluate the stress levels of the animal. It may be measured from blood, but those levels depending on the time of the sampling, and are highly affected by the sampling itself as the handling of the animals may be stressing. Corticosteroid blood levels is, thus, used only when measured by implanted devices. On the other hand, corticosteroid levels may be measured also in a non-invasive way– feathers, hair, or feces.
Those levels pull together the corticosteroids metabolized the previous day or weeks and are more useful for monitoring the animal welfare. Traditionally, animal health and welfare was monitored on the whole group by the use of sentinel animals in which veterinary analyses were conducted. Recently, the tendency is to consider each animal by itself. For this reason, industries are developing portable devices which enable the simultaneous measurement of both behavioral and biological parameters, as corticosteroid blood levels, body temperature, heart rate, on each animal. Those devices are already commercial for cows, while the ones for smaller ruminants, sheeps, and goats, are still developing.