For the past decades, animal welfare (BA) within production systems has become particularly important in cattle. This is mainly due to the pressure exerted by consumers who, more and more frequently, consider that the quality of the product is not only determined by the nature and safety of the product, but also by the welfare conditions of the animal prior and during sacrifice (1,3,4).

Colombia has not been oblivious to the problem, and a process of modernization of legislation related to animal protection has begun since 2007, which includes animal welfare component (BA) in cattle management. Consistent with this process in Law 1774 of 2016, which states that animals intended for production should be guaranteed protection. Also, it states that many techniques of the livestock sector must change, in order to reach optimal levels of animal welfare and to consider them as sentient beings that they are (5).

However, the diagnosis made by the National Council of Economic and Social Policy during 2010 established that the links that integrate the management and production of bovine meat and milk in Colombia have limitations that affect the quality, safety and BA. The environment and the type of system in which the production takes place, trigger the violation of well-being, which reflects in the low zootechnical parameters due to rigorous weather such as the one in the tropics, especially the low tropics.

The BA evaluation is then necessary due to two main reasons; The first one, inherent in the animal itself and refers to obtaining optimal standards of well-being, resulting in better and higher production, and the second, inherent in the modern consumer market that requires ethical aspects such as humane treatment for animals . It is reasonable to expect that producers in importing countries, where quality assurance systems already exist to provide for strict regulations on animal welfare, will require meat and milk producers to submit to the same standards as their countries have.

Parallel to this, the advance in ethology, besides describing the natural behavior of the species, identifies how animals perceive their environment. This has made it possible to work on the application of knowledge on animal behavior both in the design of facilities and in the development of strategies to improve animal production (5).

The objectives of this work was to evaluate, through the collection and analysis of primary information, the importance of behavioral and physiological bioindicators, and to observe their effects on dairy production in dual purpose cattle in Colombia.

Concept of Animal Wellfare

For Estrada-Cely (2) and Broom (1), “animal welfare can be defined as the specific condition of a specimen trying to adapt to a particular environment; Such adaptability acquires such importance that it may even limit their survival. “ According to the World Society Protection Animal and the World Organization for Animal Health (OIE, 2008), it can also be defined in terms of the physical, mental and natural state of an animal. These three aspects of animal status should be considered when determining their welfare. That is, a change in well-being causes a change in the physical and psychological state of the individual, which could eventually trigger behavioral change (6,7,8).

Since it is a question of assessing animal welfare, and there is no established method as such, some researchers have suggested that its application requires knowledge about the health, production parameters and typical behavior of the species, in addition to the investigation about the internal state of the animal, which cannot be measured directly. Therefore, welfare should be studied using what are called indicators or biomarkers that are a reflection of well-being (1,3), among which we can highlight:

-Degree of expression of preferred behaviors

-Variety of normal behaviors

-Degree of aversion behaviors

-Behavioral pathologies

-Physiological mechanisms to cope with the environment

-Stress

Behavioral Indicators. According to Mota et al (9) bioindicators may be grouped in the following categories:

Behavior changes directly related to stress response.

Changes in rest position and in the normal movement sequence when lying down or standing up. These changes usually result from pathologies such as lameness, lack of space or inadequate design of facilities.

Behavioral pathologies. They refer to those behaviors outside the behavioral repertoire of cattle; Among these stereotypies (repetitive movements), restricted behaviors, exaggerated reactivity, inactivity or lack of response to the environment are mentioned.

Bottaro-Morosetti (10) reports the following abnormal behaviors in the milking parlor: Playing or rolling the tongue, licking the substrate and sucking on another animal. 2) Bar-bitting: animal resting its teeth around a bar and moving the head back and forth. Tongue-rolling: animal moving the tongue, pretending to wrap a handful of pasture and winding in the direction of the open pharynx repeatedly. 3) Agonists: pitching, chasing, rising, quarrel. 4) Cohesive: social licking, charging and 5) Rare behaviors: romping, riding, falling.

Animal welfare and behavior. Behavioral changes are a good indicator to identify an animal’s state of wellbeing (5). Research has shown that sick cows follow a different behavioral pattern, such as stereotypies, anorexia, lethargy, decreased exploratory, reproductive activity, water consumption, grooming, and other social and nutritional behaviors, may indicate that the animal is not in good condition (11).

When changes are observed in cattle consumption dynamics such as grazing time and rumination, it is possible to predict diseases that are closely related to food supply or to caloric stress conditions, which affect cows (12,13).

Bovine Behavior. To identify the behavior of an animal, it is necessary to know its main advantages and disadvantages, from the physiological and anatomical point of view. In the case of cattle, it must be considered, that they are gregarious animals with a high tendency to the mimic allele, general herbivores, hierarchical (dominant - leaders - subordinates), with high paternal care. They are also learning beings by imitation and experience who live from 22 to 25 years; Ungulates of great weight, that walk slowly, always placing their posterior member in the same place in which the previous one was placed (5,6,11).

According to Suarez (13), grazing takes 6 to 11 hours a day and occurs in two periods, one at dawn and the other at dusk. As for the rumination time, it has been observed that the adult animals devote approximately 8h per day with variations between 4 and 9h, divided in 15 to 20 periods (13). This time is the sum

of: time of regurgitation, chewing, salivation, swallowing and interval between bowls.

On the other hand, rumination time is influenced by the nature of the diet and appears to be proportional to the amount of cell walls present in the forage (particle size) and other factors (14). It has been indicated that the ideal position for rumination is in sternal decubitus although in some cases it can be done standing or walking (in the case of rain or soggy grounds).

Bovine Behavior in the tropics. It has been reported that under tropical conditions, cattle spend more time standing throughout the day (15). This is mainly because the cow that is cast is more sensitive to heat stress. Based on these observations, García et al. (16) concluded that the time that cows spend laying down is inversely related to heat stress and a high proportion of the time the cow is standing is associated with high respiration rates and high body temperature.

On hot days the animals tend to graze during hours of lower temperatures, such as at dawn, dusk and at night. Holtung (17) found that the probability of grazing is higher in the morning and this has an inverse relationship with the increase in temperature, which agrees with Barragan (18), who mentions that between 12:00 -14: 00h cattle prefer to be under the shade. Other investigations indicate that animals modify their behavior at these times to counter the effects caused by extreme temperatures, looking for shade, wind and water to help dissipate heat (15).

Behavior of cattle in Colombia. The behavior of cattle in Colombia is determined by the type of system and biome in which they are found. Barragán (18) reports that, under the effect of silvopastoral systems, cattle make changes in their diurnal ingestion behavior as a response to heat stress, where they manage to graze up to 1.8 hours more than those animals that are exposed to direct solar radiation.

In studies conducted under tropical woodland environments it was found that animals grazed 4.7% longer than those in prairies with low tree coverage (15). Likewise, it has been reported that crossbreed animals between Bos taurus x Bos indicus under the same conditions as those indicated above, have a noticeable increase varying between 5 and 50% of grazing time in pastures with a tree cover greater than 23% (16) (Table 1).

Table 1

Chaux et al (20), studying in cattle under tropical conditions in the department of Caquetá, found that heat stress influenced the number of offspring born in a dual-purpose system. This author indicates that in the summer months (December, January and February) where high temperature and humidity indexes (ITH) were reported, with values above 76%, there was an associated lower probability of bovine births. However, between the months of lower caloric stress (June and July) with 73% of ITH, the highest number of births was found. This is probably associated to a higher availability of forage in these months, due to the decrease of precipitation, loss of forage by mudding and increase in photosynthetic rate.

Behavior in enriched prairies.Under enriched forrage where there are dispersed trees and other types of silvopastoral systems, the diurnal behavioral patterns of cattle are different compared to those that do not include trees in the prairie. It has been indicated that the time devoted to grazing is 22.15%, in relation to animals grazing in pastures without enrichment (15,20). Similarly, Patiño et al (14) reported an increase in the percentage of time spent grazing under this type of grassland, up to 65% higher than shade-free systems (21). In physiological terms, these production systems minimize the heat load in the animal, because they have uniform shade in the paddocks, registering a reduction of rectal temperature of up to 0.5°C (22,23).

Nocturnal behavior evaluations performed in an intensive silvopastoral system, Ceballos et al (24) found that cows have a cyclical consumption behavior, rumination and rest at night, presenting three consumption peaks and devoting more time at night to feeding behaviors compared to two peaks in those grassland-only systems.

In terms of animal productivity, enriched prairies have also shown beneficial effects, in agreement with the reduction of animal stress and thus a better performance in milk production. According to Zuluaga et al (25), enriched systems report increases of between 20 and 50% in milk production per day compared to treeless systems during the dry season. Also, in systems with high tree coverage, a 1 liter increase in milk / animal is indicated, compared to systems with low tree coverage (15).

Stress. Stress can be defined as a situation in which the dynamic equilibrium (Homeostasis) of an organism is modified as a consequence of the action of an intrinsic or extrinsic stimulus (20). An animal responds to such changes in its states in a number of different forms, including a range of physiological and behavioral responses; so an effective mechanism for assessing the welfare of a specimen is the measurement of such responses.

Effect of stress on animal behavior. Behavior in response to stress is defined as “all those behavioral phenotypic traits that the animal can modify.” Among these activities, the most important are those that make up the grazing behavior, described as the sequence of events (ingestion, rumination, drinking) that the animals perform in obtaining food for maintenance and productivity.

At present, the evaluation of grazing behavior has taken a lot of interest due to the valuable information that is obtained (17). This information can be applied in management practices to increase productivity and ensure better health and longevity in the animals, as well as to measure the effect of the environment under hostile conditions for the animals (26).

Over time, animals have adopted certain behaviors to be able to regulate body temperature more easily. It is known that, under heat conditions, the cattle extend their limbs to facilitate mechanisms of heat loss. Also, those living in tropical areas look for available shade and graze in the coolest hours of the morning and afternoon. Another thermoregulatory behavior of heat conditions is that they separate themselves from each other or to stay away from each other (27,28).

Effect of stress on milk production and quality. The alteration of homeostasis in the animal, besides affecting the volume of milk produced, also affects its quality. Lagger et al. (29) indicates that under stress conditions, the animal decreases the voluntary consumption of food and increases its selectivity to avoid the

ingestion of foods that produce a lot of heat from fermentative processes. When a reduction in the concentrations of thyroxine and glucocorticoids occurs, the basal metabolism also decreases to reduce the production of heat and this in turn, induces a decrease in food consumption (28,30).

This leads to a decrease in the total intake of nutrients necessary for the synthesis of milk in the mammary gland. These alterations reduce their functionality, affecting the quality of the milk produced. It is estimated that the non-fat solid content and protein in milk can drop to 18.9% and 16.0%, respectively, when the cow is under stress (31).

Another factor affecting milk production is the close relationship between the mother-offspring. Those cattle in dairy production where cows are allowed to suckle their babies to ingest their food, react by secreting more cortisol and consequently higher levels of stress that are reflected in lower production. During weaning, both mothers and offspring are subjected to severe stress, which is reflected in low weight gains, as well as the compromise of their immune system in this type of situation (6).

Response to Stress

Morphological Adaptations. Bovines in tropical and hostile environments, such as those in the Amazon, have had to undergo a series of adaptations; Compared to European cattle. It is known that Bos indicus has a greater reflection than Bos taurus, which gives the first an adaptive advantage to resist the incidence of infrared rays. Regarding evaporative cooling, B. indicus presents a greater sweating capacity than B. taurus (32).

Cebu cattle and its cross breeds show greater tolerance to heat than European cattle. This tolerance does not seem to depend on the sweat capacity, but on a lower heat generation, which may be due to its lower milk production level, lower feed intake and lower basal metabolism (31,32).

Physiological responses. Relevant changes to stress include, increased respiratory rate, heart rate, sweating and vasodilation (33). As noted above, when an animal is affected by a stress factor, its organism undergoes physiological changes that lead to increased release of adrenergic and corticotrophic hormones, which in turn alter the water retention capacity, color, meat and milk pH (27).

In caloric stress situations, Barragán (18) reports that heat loss in cattle occur through different mechanisms, including sensible and insensitive heat losses. In the former, conduction, convection, radiation and evaporation are counted, which are conditioned by the thermal gradient between the skin and the environment. The latter comprise evapotranspiration which depend on the amount of water vapor.

It has been observed that the respiratory rate in an animal with thermal stress can increase from 60 to 200 exhalations per minute to lose heat through the respiratory tract when the relative humidity is not limiting (28). However, the increase in respiratory rate, superficial in terms of the amount of air inspired in each cycle, does not guarantee the adequate oxygenation of the blood, which can lead to the occurrence of a respiratory alkalosis, characteristic of its high concentrations of blood bicarbonate (HCO3-). The body of the animal will then try to evacuate the excess of HCO3- through its excretion through the urine, as a mechanism of reversion of the process towards a metabolic and ruminal acidosis, because the rapid recovery of homeostasis, Limits the availability of HCO3- in saliva, and from here, its subsequent transit to the rumen (24).

It has been observed that the respiratory rate in an animal with thermal stress can increase from 60 to 200 exhalations per minute, in order to lose heat through the respiratory tract when relative humidity is not limiting (28). However, this increase in respiratory rate, with a rapid and shallow behavior, alters the acid-base condition of the blood by loss of CO2, reducing the concentration of carbonic acid (H2CO3), with a consequential increase of the concentration of bicarbonate (HCO3-) in the blood, resulting in respiratory alkalosis. Subsequently, in order to maintain pH homeostasis in the blood, excessive excretion of HCO3-, in the urine to regulate its levels, ends this process in a metabolic acidosis (34,35), as well as ruminal acidosis, due to the decrease in the amount of HCO3-, available in saliva and its flow into the rumen (35,36).

It is known that there are ranges of tolerance to ambient temperature, called thermal well-being for animals. In this respect, it has been indicated that the best temperature and relative humidity conditions for rearing animals are generally around 13 to 18°C and 60 to 70% relative humidity (16).

The ambient temperature ranges reported as comfortable for Bos taurus animals range from 0 to 20ºC and for Bos indicus from 10 to 27ºC, with 70% ambient humidity in both cases, although

differences are reported between races, age, physiological state, sex and individual variations (29). When subjected to temperatures above this range, they respond through compensatory mechanisms such as respiratory and cutaneous evaporation, which have a high energy expenditure (37). When such mechanisms are insufficient, the body temperature increases producing hyperthermia or thermal stress. As is known, bovines are homeopathic animals and under normal conditions a dairy cow has an internal temperature of 38.5°C, a heart rate of 60-80 beats and a respiratory rate of 10-30 movements per minute (38).

Man-animal interaction. The animals are subjected to manipulations whenever it is necessary to intervene on them for sanitary purposes (dehorning, vaccination, preventive curative treatments), or for management reasons (change of accommodation, transport, group formation, etc.), both individually and as group (2). Most of the negative effects of this interaction are related to the fear that the animal poses to the mere presence of man.

Measurements of the degree of fear of the animal have many overlaps with controls to determine the degree of well-being. Among the behavioral type criteria, the most used is the control of the reactions and the flight distance when they are aware of the presence of man or his approach (39). In this regard, it has been indicated that the inadequate handling of cows inside stables during the milking process can generate fear and rejection, causing a reduction in milk production (9).

Liu et al (30) found that when cows were treated with positive stimuli during milking, using music, caring objects or human contact on the head, milk production increased. The effect of music on milking cows is positive by being milked voluntarily and showed an increase in milk production. In this sense, it was found that a higher number of cows went voluntarily to the milking parlor when listening to music (45.0±18.0%) compared to periods where music was not used (35.1±15.4%). It was also found that not only music has a stimulating effect on the behavior of cows, but also stimulates a greater milk production and allows for the development of own behaviors, habituation and less stress.

In cattle management, it is particularly important to know the existence of the so-called escape zone defined as the minimum approach distance allowed by an animal before the onset of flight. Thus, for an animal to move forward, it will be necessary for the person to be positioned within the region of escape in the region from the point

of balance to an angle of 45° in the direction of the animal’s tail (40). If the person is located more frontally, the tendency to move of the animal will be backwards (5,9). If you pass the angle between 45º and 60º in the direction of the tail, the animal will stop when entering the blind spot of the animal’s vision, where the tendency will be to turn the head and look for the person to be able to visualize it, interrupting Its movement or walking in circles (16).

It is recommended that small batches of cattle (10 to 15 animals) be used, since very large groups are more difficult to control, increasing the risks for both the animals and those who drive them. The hierarchy, established by alliances or aggressions and that lasts over time, determines who are dominant, subordinate and intermediate. In lots of 50 or more animals, those in the front end up not seeing the commands and can end up making the entire handling difficult.

There are management situations in which it is possible to use the social character, using animals known as “godmothers”, who are usually docile, and trained to pass through the facilities; Thus, once introduced into the group, initiate movement facilitating the entry of the rest of the animals in the batch.

It is known that cattle are animals of high parental care, high learning ability and gregarious instinct, so they are strongly affected by social isolation, which impacts on the performance and quality of meat.

It is important to indicate that bovine animals recall positive and negative events, particularly during the early stages of their development, so that greater human contact accompanied by positive stimuli will allow easier management in the future.

If dehorning is required, it should be done in neonates using a combination of local anesthetics and non-steroidal systemic analgesics. A positive compensation that facilitates the overcoming of the traumatic event will be of great benefit.

To move animals Denelón (41) reccomends:

-Do not mix categories, sizes or states

-Do not exceed or substantially reduce the load capacity of the roads (400 kg/m2), as piling increases trampling, and low loads, allow animals to easily lose balance.

-Do not scream or whistle, as they are very sensitive to sharp sounds

-Avoid the presence of dogs inside the pens; To be used, only in open field and previously trained to harness or using muzzles. It is possible to substitute them with the use of bags, since the cattle tends to move away of plastic sounds.

-Have the necessary time and in any case, avoid physical contact.

-Make the shipment at dusk or at dawn, placing a dim light at the end of the truck, avoiding very high ramps (slope ≤25°) and ensuring a perfect closing of the truck head.

Reduction of dry matter consumption. The reduction in food consumption aims to reduce the production of heat from fermentation and the derivative of physical activity (walking to cribs, chewing and ruminating). Above 18°C, consumption starts to decrease and from 30°C decreases sharply, so that at 40°C consumption does not reach 60% of the value in the thermoneutral zone (42). Part of the effect of high temperatures on consumption is because the reduction of motility of the digestive tract causes a filling effect.

Effect of stress on physiology. Physiological changes relevant to caloric stress include increased respiratory rate, heart rate, sweating, and vasodilation. However, these responses induce deleterious effects on the productive capacity and the physiological status of the animal (34,43).

It has been observed that under adverse environments in terms of temperature and humidity, body temperature increases as a response to heat load, generating a state of caloric stress in cattle (34,35). This leads to a response in blood chemistry with cycles of alkalosis-acidosis during the day altering the homeostasis of the animal (34). Additionally, this alteration increases the respiratory rate, inducing a muscular effort that will be reflected in a higher energy expenditure, which represents an increase of up to 18% in nutritional requirements (28).

It has been suggested that the main physiological mechanism to control body heat loss is the modification of blood flow to the body surface and redistribution (42). Peripheral vasodilatation facilitates sensitive heat loss by reducing the effect of tissue insulation and promotes the removal of heat via evaporation by facilitating the diffusion of water from the skin. Respiratory rate modification regulates heat loss through exhaled air from the lungs. In addition to physiological adaptations, animals through their behavior, may alter the effectiveness of isolation. Thus, using postural changes to modify the exposed body surface (eg to reduce the effect of wind), they reduce the area of contact with the ground avoiding lying down or seeking protection from the sun and rain.

Effects on grazing. In high thermal media, cattle tend to reduce their heat production through voluntary anorexia (44). This decrease in the consumption of food, as a mechanism to reduce the thermal load is reflected consequently in their grazing behavior, since, when grazing less, they reduce both the consumption and the muscular activity deployed in the search of the same; This is how these animals change their grazing habits, performing it at night hours where temperature is lower. This effect of solar radiation on grazing behavior is important because it indicates the need to provide good night grazing to animals that have to endure daytime temperatures of 26°C or higher or to provide them with shady pastures, preferably trees (45).

Temperature-humidity index (ITH). Milk cows are particularly susceptible to changes in ambient temperature. Effective temperature depends on ambient temperature, relative humidity, ventilation and radiation (40). One of the parameters that is most frequently used to reduce the stress risk in cows is the Tempreture-Humidity Index (ITH), which is obtained from the ambient temperature and relative humidity using the formula ITH=0.8°Ta+((Relative air humidity/100)*(Ta-14.3))+46.4; Where Ta = air temperature [°C]; Or by using the ITH table.

When the ITH is greater than 72, milk cows begin to express the negative consequences of the effect of caloric stress. García et al. (16) point out that the ITH has been developed to monitor and reduce losses associated with caloric stress. According to Patiño et al (14) the ITH for Bos taurus cattle can be grouped into four categories: Normal <70, ITH maximum <74; Alert, ITH maximum <78; Dangerous, maximum ITH <84; Emergency, maximum ITH≥84 (Table 2).

Table 2

ITH is an excellent environmental indicator of thermal stress in livestock facilities. When it is higher than 72 measures must be taken, as it can lead to a reduction in milk production of the order of 2 kg/cow/day. Other important indicators of thermal stress are body temperature (> 38.7°C) and respiratory rate (> 80 moV/min), which is an excellent predictor of thermal stress in dairy cows (38).

In conclusion, stress triggers acute and chronic problems that produce physiological alterations and affect animal behavior. Factors such as adverse climates, changing environment, annoying noises and high animal density cause stress. All this triggers serious problems that decrease production.

A better knowledge of the behavior of the animals will result in a powerful tool for a better understanding of how the animals perceive their environment and how they react to it. This knowledge will allow for an efficient way to guide producers on how to incorporate ethological management, in order to obtain better animal welfare and therefore greater production.

On the other hand, a proper infrastructure that allows an optimal handling of the animals will be of great help if one wants to increase production. For this, it is necessary to know more about ethology of the geographical region where the animals are. It is essential to carry out specific investigations, carry out training campaigns in BA to evaluate and demonstrate economic losses due to lack of implementation to those responsible for animal management in the production chain.