Evaluation of the behavior of dairy calves bred in tropical climate

The purpose of this study was to evaluate the behavior of dairy calves bred in tropical climate. Six calves of the Girolando breed at 3 months old in average were used. For the elaboration of the ethogram, the focal animal sampling method was used for five days. The Analysis of Variance was run and treatment means were compared by Tukey’s test at 5% probability. Findings show that calves spent more time in the concentrate intake and foraging, the rumination occurred more frequently during the night, and no significant differences were found between the water intake and the leisure activity. The thermoregulation behavior regarding the shadow demand did not differ statistically when compared to the sun rays demand. However, animals remained in the standing position for longer in the afternoon, and spent more time walking in the morning. Statistical differences were found between the playing interaction 1 and the playing interaction 2, and there were no statistical differences between the stereotypy and vocalization. Therefore, the behavioral states were found to be indicators of the good welfare degree for calves kept in a tropical breeding system.


Introduction
The topic about animal behavior and welfare in Brazil was little understood and studied few years ago. This is the reason why there was no much concern regarding environmental conditions where animals were bred, the way how they were managed, even if their basic needs for the maintenance of vital functions were being attended.
However, a greater concern has emerged from the current state of understanding of the animal health and welfare, as well as from the interest of the society. This trend contributed to the increase of the importance of the biological and physiological knowledge, and the natural behavior of species, so that the animal health and welfare are not affected.
The state of the animal usually interferes directly in its life quality, thus compromising its welfare and putting at risk the quality of animal origin products such as milk, meet and eggs. On other hand, it is essential for consumers that beef animals live relatively in natural environment to allow them expressing their innate behaviors.
Taking into consideration concerns regarding the animal welfare aspects, analyses on the effect caused to the behavior of dairy calves bred individually, with no social contact to each other, were carried out. This made the European Union to prohibit the individual breeding system for calves at over 8 weeks old, thus showing that the group breeding system of calves allow natural social interaction among them. Besides, animals bred in group are found to be more active, favoring desirable behaviors and increasing productivity rates (Oliveira et al, 2005;Von Keyserlingk et al., 2009).
Understanding the needs and the behavior of bovines becomes complex, once there is a literary scarcity of the behavioral biology regarding such species. Scientific studies bring new perspectives and afford the comprehension of mistaken situations (Façanha et al., 2011).
However, the characterization of behavioral and feeding patterns of dairy calves is found to be important, since they are related to the animal health and welfare. Establishing such patterns becomes relevant in the decision making process Development, v. 10, n. 3, e26310312965, 2021 (CC BY 4.0) | ISSN 2525-3409 | DOI: http://dx.doi.org/10.33448/rsd-v10i3.12965 3 regarding nutrition and management of animal production systems (Svensson & Jensen, 2007;Carneiro et al., 2020).
The study aims at evaluating the animal behavior of dairy calves kept in a tropical breeding system.

Methodology
The experiment was conducted in December 2014 in the Dairy Cattle Section of the Center of Agrarian Sciences at the Federal University of Paraiba -Campus II, Areia -PB, located in the Brejo Paraibano Microregion, at 618 elevation, 1,400 mm average rainfall per year, and temperature from 12°C to 31°C. According to data obtained from the Weather Station of the Center of Agrarian Sciences, the average of the air temperature in the study area rounded at 25.5°C during the assessment period.
The study accomplished rigorously the existing international norms regarding animals use in research, also complying with the law on animal welfare.
Six calves of the Girolando breed at 3 months old in average, 4 males and 2 females, were used for behavioral assessment. Animals were submitted to the adaptation period for one day, followed by 5 days for data collection. Data regarding the behavior were recorded on a specific ethogram for the animal category under study.
Animals were arranged in an argentine-type calf (shadow-net at north -south direction) with availability of individual shelters (east -west). This breeding system allowed the access for sun rays inside the whole calf area, thus reducing the existing humidity from animal feces and urine on the ground, and minimizing the proliferation of pathogenic microorganisms, causal agents of diarrhea and breathing problems. This breeding system model also allowed the availability of wide space for animals locomotion, thus prevent them from doing physiological needs in the same ground within the facility.
Each animal was restrained with a collar connected to a chain 1.5 meters length tied to a steel wire 10 meters length, supported by two poles (Figure 1,A,B). A total of 72m 2 shadow-net (24 m length × 3 m width) were available for the six animals, where each animal was in 12m 2 area (4 m length × 3 m width) ( Figure 2). Individual houses and the steel wire were at north -south direction. Animals had access to the shadow and sunny areas, allowing them to interact to each other, also having physical contact either from the right side or left side.  Individual drinking fountains and feeders were provided to each animal during the experimental period. The supply of liquid feed (succedaneum) was done twice a day at 08:00 a.m. and 3:00 p.m. The mineral salt, water, and corn and soybean meal based concentrate mixture were provided ad libitum. There was also pasture of Brachiaria decumbens cv. Basilisk grass available in the experimental plot.
Focal animal sampling method was used for data collection thrice a day (12 hours observation a day): in the morning from 08:00 a.m. to 12:00 p.m., in the afternoon from 02:00 p.m. to 06:00 p.m., and at night from 07:00 p.m. to 11:00 p.m. The sampling method was adapted from Martin and Bateson (1986). Data on the behavior of each animal were continuously recorded (using the ethogram) by properly trained animal observers positioned at 8 m distance from the calf to avoid casual human / animal interaction and the influence on the animals natural behavior (Table 1).

Concentrate intake
To place the head in the feeder and consume the diet.

Foraging
To collect the food with the mouth in the pasture.

Rumination
The repetitive regurgitation of food, which is then partially or completely reswallowed or rechewed.

Leisure
With no apparent activity, standing or lying.

Shadow
Period of time in which the animal remained in the shadow.

Sun
Period of time in which the animal remained in the sun.
Playing 1 Animals playing to each other, promoting social interaction.
Playing 2 Playing activities toward inanimate objects.
Walking Slow locomotion.

Stereotypy
Time spent by the animal performing repetitive behaviors.
Water intake To place the head in the drinking fountain and consume water.

Vocalization
Emission of sounds with no apparent meaning.

Posture
Prone position Animal with its ventral side against the ground.
Lateral decubitus Position in which the animal lies on its side.

Standing
An upright position and supported only by the feet, not moving.
The Analysis of Variance was run for data on the animal behavior by means of the generalized linear model, considering the log-normal distribution for variables expressed in minutes, and the negative binomial distribution for variables expressed in frequency. Treatment averages were compared by Tukey's test at 5% probability. The SAS statistical software (Statistical Analisys System, 2010) was used for data analyses.

Results
The time recommended for behavioral observations allowed detecting the period in which animals spent less time in the concentrate intake. Table 2 shows that calves remained more time in the concentrate intake activity in the morning and in the afternoon. The foraging behavior varied among the shifts studied (P<0.05), where greater activity was recorded in the dayshift (in the morning and in the afternoon), and a decrease was recorded at night (Table 2). No differences were found either for leisure or water intake in the shifts studied (P>0.05). Significant differences were found for rumination between shifts (P<0.05) ( Table 2), and animals ruminated for much time at night regardless the animal age.
The animal search for shadow and sun did not differ between shifts (P>0.05), as well as the position in which animals lay, whether it was the prone position or lateral decubitus. Animals remained in the standing position for longer in the afternoon, and they were motivated to walk in the morning, since they remained standing in the upright position in the afternoon, not moving (Table 3).  Table 4 shows that animals stayed for much time walking in the morning. Besides, statistical differences were found between the playing interaction 1 and the playing interaction 2 (P<0.05), according to shifts assessed. Stereotyped behaviors (sucking another animal's prepuce, nibbling the chain and the steel wire) did not differ between the shifts (P>0.05). Calves found themselves motivated to show this behavior in the afternoon and at night. There were no significant differences (P>0.05) regarding vocalization between shifts (Table 5).

Discussion
The findings in this study show that animals were in a good state of welfare, since the foraging occurred either in the morning or in the afternoon, and the rumination occurred more frequently during the night. This show that animals had normal behavior; the environmental temperature was comfortable and did not interfere in the animal feeding, since high temperatures during the day forces animals to search for shadow.
The lack of significant differences regarding vocalization between shifts was also described as an indicator for good animal welfare, since it indicated that animals did not show differences in vocalization for shifts assessed. According to Zanine et al. (2007), the Brachiaria decumbens species has low ratio blade ÷ stem, what explains the most selective behavior of calves, reduces the frequency of mouthful uptake, and contributes to the increase in time spent for animal pasturage.
The temperature during the assessment period remained mild, the reason why there were no changes in the water intake during the day. According to Issakowicz et al. (2020), the heat is retained by the atmospheric water vapor and increases the thermal sensation of heat for animals, and also the water intake. The animal water intake usually aims at dissipating the heat when the animal is in a heat stress condition. However, such did not happen in this study, since either the feeding or the rumination occurred in the common time, did not go away from normal, and there were no differences regarding water intake between shifts.
Unlike that, Façanha et al. (2011) studied the behavior of dairy calves and found that animals ingested more water in the warm period, between 12:00 p.m. and 02:00 p.m. This may indicate the animals attempt to lose heat, since they demanded for much water in the warmer period of the day.
The animal's constant activity, assessed by the foraging behavior, concentrate intake and rumination in the day and night shifts, contributed to shorten the leisure time. According to Zanine et al. (2007), calves remained greater time at the leisure time in the night shift, specifically from 10:00 p.m. to 01:00 a.m., and from 04:00 a.m. This statement support findings from this study, since observations were carried out at night until 11:00 p.m.
The animal leisure is usually shown more frequently in the quietest times, with mild temperatures across the study area. According to Zanine et al. (2007), animals usually spend most part of the available time foraging, and this activity is reduced at night since animals spent time ruminating and also in the leisure. Oliveira et al. (2007) mentioned that animals with access to the grazing area usually start pasturing in the first and in the second week of life. This event marks the beginning of the development process of the rumen -reticulum, which reaches the proportion of the adult individual about eight weeks age and marks the transition from the pre-ruminant phase to the ruminant phase.
During the observation period, the weather remained cloudy throughout the day with 25.5°C average temperature.
According to Bond et al. (2012), animals do not need changing their behavior, aiming at adjusting the body temperature when this ranges within ideal limits for animal thermal comfort, which are between 10°C and 30°C.
Animals use special mechanisms to regulate the body temperature when they feel thermal discomfort and, depending on how the animal lies, the posture may increase or reduce the contact area that affects the rate of heat transfer from the animal to the environment or from the environment to the animal (Almeida et al., 2020). According to Degasperi et al. (2003), Animals can transfer heat from the body to the environment from two different ways: (i) sensible heat transfer that occurs by convection, conduction and radiation; and (ii) the latent heat transfer, which occurs when the temperature increases, by sweating or by increasing the respiratory frequency, and is influenced by the air humidity and also by the temperature, according to Souza and Batista (2012). The temperature control is essential for keeping animals in a good state of welfare, since the heat stress can influence many other activities (Almeida et al., 2020).
Healthy animals are usually motivated to do different behavioral activities, such as by walking, also exercising the paws and improving blood circulation. According to Façanha et al. (2011), one of essential factors to be taken into consideration when dealing with calves in the development stage is the need for sufficient physical space for mobility.
Animals were motivated to move from a place to another, mainly in the morning and in the afternoon, even when were in permanent contact with nearby animals. According to Campos and Campos (2004), animals usually interact to each other, thus stimulating the learning and the early consumption of solid foods. According to Bond et al. (2012), the grouping of calves in small lots contributes to reduce the animal stress caused by socialization and lucid behavior.
The stereotyped behaviors did not show any effect, likely because they were not sufficiently expressive during the observation period. Such behaviors were mostly associated with restrictive conditions of the breeding environments.
According to Bittar et al. (2009), experimental evidences show that the stereotyped behavior of the cross-feeding may occur when animals are housed collectively, and the occurrence of this behavior before and during the weaning process may depends on the amount of ingested milk or energy, as well as can be affected by the weaning method used.
According to Broom and Molento (2004), animals that show behaviors indicative of self-mutilation, stereotypes, overly aggressive behavior; are usually found to be in a bad state of welfare.
Findings from the lucid behavior show that animals are more motivated to play individually in the afternoon and at night. According to Façanha et al. (2011), animals bred in individual shelters with about 28.2 m 2 external area available, appear to have greater freedom of movement. However, calves bred in masonry shelters (individual stalls), with limited space, tend to have a locomotor-rotational movement, occasionally changing this social behavior by other, such as kicks or jumps.
Even after verifying higher frequencies in the emission of sounds when the liquid feeding schedules were approaching, Bond et al. (2012), stated that when the food is provided in limited quantities, animals tend to show behaviors that indicate chronic hunger, expressed by the increase of screams, i.e., vocalizations from calves, that usually cause a decrease in other activities such as playing.
Vocalization measures can be indicative of stress, fear, pain, among other effects. Silva (2007) estimated the stress condition of her-calves in breeding stalls using a measure of vocalization. Results on severe frequency peak were divided into two groups: elder her-calves (47 and 22 days) and younger her-calves (3 days). Averages on frequency peaks bellow and over 7 kHz recorded during the experiment where then calculated. Findings showed that there were no significant differences among peak noise incidences, although the younger her-calves maintained their vocalization for longer than the elder hercalves. In this study, no significant differences were found (P>0.05) on vocalization; however, a higher frequency was observed in the afternoon due to the supply of liquid food for calves, thus demonstrating a possible state of hunger. Nascimento et al. (2013) stated that, to characterize whether the animal is or not in a good state of welfare, there are various indicators that can be used, one of them is the observation of animals focusing on behaviors shown under thermal stress, as well as on physiological responses shown by them.
Animal behaviors shown in this study, such as drinking water in different day shifts with no distinction, and foraging either in the morning or in the afternoon, may be used as indicators of good state of welfare; instead, animals would have shown different behaviors. In this study, the animal welfare was, in general, considered good, since behaviors that are usually associated with a bad state of welfare, such as stereotypes, vocalization and luck of playing, did not have any effect in the experiment.

Conclusion
The behavior of dairy calves of the Girolando breed at 3 months old was evaluated in the following shifts: in the morning, in the afternoon and at night. The intake behavior, the thermoregulation process and the walking activity occurred more frequently in the day-shifts; the social interaction to each other or with inanimate objects in the facilities was prevalent in the afternoon and at night; and the rumination occurred mainly during the night.