1 - MILK COWS

In the breedings of milk cows the summer climate involves every year damn economic damages due to the worsening of the productive and reproductive performances of the bovine, especially of those to high production.
Over that to the reduction of the fertility and the consequent increase of the period of interbirth, the cows submitted to heat stress underlines with great frequency probrems of embryonic mortality and distoic birth (Putney et to the., 1989; Jacobsen, 1996)..
Besides when environmental temperature increases, is found a voluntary reduced assumption of foods that determines substantial decreases in the milky production; at 30°C the assumption of dry substance results reduced of 10% in comparison to the normal one, while to 32°C the decrease is of 25% and to 40°C is even of 93% (Mc Guire et to the., 1989). Another negative aspect is constituted by the qualitative worsening of the milk (contents in proteins, contents in fat, acidity, etc.)
This is particularly felt in the breedings that produce milk destined to the transformation in cheese; in the most serious cases the alteration of the chemical-physics characteristics of the milk can be such to prejudice the same workmanship.
Other negative effects have strictly tied to the physiological adaptation of the bovine to conditions of stress induced by the summer climate.
The cattle as the whole animal omeotermis, maintain constant their inside bodily temperature (around 38,5 °C) with the purpose to safeguard the vital functions of the organism. The production of heat or termo genesis, depend on the type of animal (race, age, weight, sex, phase of breeding, physiological condition and sanitary condition), from the activity of the animal (type of stabulation) and from the level of the food ration.

The phenomenon of dispersion of heat from the bovine is influenced from different factors; of great importance are the climatic parameters and the thermal resistance that is opposed to the passage of heat from the body of the animal to the surrounding environment. 
The principal physiological answers of the animals to the heat stress are: 
- the small ingestion of foods; 
- the greatest ingestion of water; 
- the change of the metabolic rhythm and the energetic requirement; 
- the greatest losses of water for evaporation; 
- the increase of the respiratory rhythm; 
- the change of the of hormones concentrations in the blood; 
- the increase of the bodily temperature.

From the point of zootechnic view the principal orientations to reduce the effects of the thermal stress are: 
- the improvement of the environmental conditions of breeding; 
- the genetic improvement of the milk cattle; 
- the adoption of suitable techniques of rationing.
Less it is the production of heat from the animal, great it is energy's quantity destined to the zootechnic productions.
The optimal relationship between environmental temperature and relative damp in relationship to the maximum production of milk is of 23-24 °Cs at 55% of damp; overcoming said values on note that to 29-30 °C the decrease of 20% of production are verified. If on arrive to values of 39-40 °C with 60% relative damp on have that the productive decrease arrives at 40-45%.

2 - SWINES

The swines are animal omeotermis and therefore they have to maintain constant their inside bodily temperature (around 39 °Cs) with the purpose to safeguard the vital functions of the organism. 
The possibility to expel heat results of fundamental importance for the swine that can opt for the most efficient solution in that date situation according to the circumstances. 
When a swine is found in warm environment (in the swine the rectal temperature starts to climb when the temperature environment overcomes the 35 °Cs), the mechanisms of sensitive dispersion result compromises and the evaporation assumes prevailing importance, the behavior also changes radically:

- the swine often assumes the position of side decubitus that offers the maximum bodily surface to the air and the contact with the floor; 
- search isolated positions and possibly in the zones submitted to the greatest tide of air; 
- it limits the ingestion of food but it considerably increases the consumption of water of drink; 
- it uses, where possible, the drinking trough also as " shower " and it is laid down on the floor bathed from the water or from the defecations. 

These attitudes cover a great importance for the limitation of the heat stress in charge to the adult swines raised on full floors; for against they worsen the hygienic conditions of the box. During the summer months, for how much you are taken care of the box's coibentation and increases the ventilation, it results difficult to maintain the temperatures on acceptable values. This is been reflected negatively on the performanceses of the animals, with problems on the reproductive sphere (summer ipofertility) and worsening of the productive results (small increase of weight).

(tratto da Professione allevatore, Febbraio 1998; P. Ferrari, P. Rossi, A. Gastaldo, Centro ricerche Produzioni Animali, Reggio Emilia)

2 - POULTRY And RABBITS 

The tall temperatures, that often are present in the summer period, submitting the animals to an not indifferent metabolic stress, induce a diminution of the appetite that translates each other, in the subjects in growth-fatten up, in a small growth, in a productive worsening in eggs production and in a reduction of the milky secretion in the rabbits. 
The tools to disposition of the breeder to maintain the environmental parameters within the zone of comfort, is the thermal isolation and the ventilation / cooling. 
While ventilation /cooling are including easily realizable interventions during the construction of the building, the coibentation remains wich anticipated in phase of construction, to less following rather complex and onerous interventions. 
In U.V.R. , the evaporation is entrusted the thin water's pulverization given out by the centrifugal disk in such manner that this introduces an elevated surface of contact to the current of air.
An interest must be remembered in zootechnic field, and particularly in the poultry sector, for his multi-use, being also usable for disinfections and treatments for the demolition of the odors.

(tratto da Professione allevatore, Febbraio 1998; A. Someda, Ist. Tec. Agrario di Spilimbergo, e M. Leonarduzzi, Universita' degli Studi di Udine)