**2.4 Male social hierarchy and its impact on reproduction**

One of the key aspects to improve the performance of the herd is the proper evaluation of the reproductive capacity of the male, performing both a general physical examination, a specific examination of the reproductive system, a seminal quality examination and another of their libido and ability to mount. [33], with the aim of ensuring an adequate selection of males that contribute to improving the efficiency and profitability of the reproductive unit (**Figure 3**).

Previous studies have evaluated the social hierarchy in rams raised in pairs, identifying that the dominant males exhibit a greater sexual precocity and a greater reproductive capacity compared to the subordinate males. A negative influence on testosterone production has also been reported, due to the stress of the grouping of bucks [34–36].

In goats housed in herds with different densities, the social interactions registered between them were evaluated, as well as the levels of cortisol in blood to determine if the levels of said hormone vary depending on the size of the herd,

#### **Figure 3.**

*Factors influencing the presentation of the male effect in goats.*

identifying that the size of the pen and the size of the herd influences the increase in stress due to clustering, negatively impacting the weight gain of the bucks and the productivity of the herd [37, 38].

Ivasere et al. [39] recorded behavioral changes by intensifying production systems and their effect on productive aspects such as nutrition, reproduction and diseases. They observed that the social structure is of great importance in the physiological and ethological development in bucks, modifying the frequency of courtship, copulation and the stress level in bucks grouped in herds of different densities. So far there is little information in the literature about the effect of regrouping previously raised male goats in pairs and regarding how serum cortisol and testosterone concentrations, seminal quality and sexual behavior are affected after such grouping.

### *2.4.1 Cortisol and stress physiology in bucks*

Within the management of goats, efforts have been made to develop strategies to improve the quality and efficiency within the herds. At an intensive level, the management carried out ranges from supplying drugs, palpation, semen extraction, and pen cleaning. These management activities, in conjunction with other factors, such as the size of the herd, overcrowding, feeding or the immune system of animals, influence the body's physiological response to various stressful situations [40]. The most common stressors in goat production are mainly those caused by environmental heat and the increase in body temperature, deprivation or lack of access to food or water, as well as modifications in the hierarchical structure of the herd or change of habitat [41].

Among the responses at the physiological level present in male goats in stressful situations is the secretion of glucocorticoids (GC), which exert a negative feedback effect on the hypothalamic-pituitary-gonadal axis, reducing the synthesis of GnRH and together thereby inhibiting the synthesis of gonadotropins and sex steroid hormones [34, 39]. This endocrine mechanism aims to stimulate the body to respond to stressors, such as loss of appetite, suppression of the immune system, energy mobilization, vasoconstriction, and loss of erection and receptive sexual behaviors [42].

#### *2.4.2 Social factors and sexual behavior in males*

The grouping of bucks is a widespread practice mainly in stable and mixed management systems around the country [17, 43].

The study of behavior has shown that the establishment of hierarchical ranks and social organization influence sexual behavior that will be exhibited by a male under grouping conditions [44]. This dominance is related in turn to the live weight of the animal and its age, mainly as part of a display of reproductive competition, which guides producers as a key criterion for selecting males [45, 46].

By remaining in coexistence conditions, one of the males tends to monopolize access to the females in estrus in order to ensure their reproductive success, being this considered the dominant male [47], which initiates a display of dominance behaviors, such as competition due to access to food, increased physical activity and hoarding of better resting places, while the subordinate male at the hierarchical level initiates evasive or submissive behaviors and sexual behavior is characterized by opportunistic-type strategies [48]. The dominant male is characterized by having a more aggressive behavior compared to the rest of the males and is also the one with the highest sexual activity [49].

Among the activities carried out mainly by the dominant male, the increase in vocalizations, head movements, tapping, lunges and displacement and protection

**81**

male [11].

*Reproduction in Small Ruminants (Goats) DOI: http://dx.doi.org/10.5772/intechopen.93481*

inhibit the sexual behavior of subordinate males [36].

*2.4.3 Measurement of sexual behavior in bucks*

weight, body condition, and sexual behavior [1].

ejaculations occur as the case may be [42].

program in natural mating in the shortest possible time [52].

of the female in heat (tending) from other males stands out [42], thus reaching

of semen in dominant bucks compared to subordinate's increases [36].

According to Mainguy et al. [41], the establishment of the dominance position is accentuated with the secondary sexual characteristics, which is also related to the age and body weight of the animal [50], helping to strengthen the male's hierarchical position and social structure within the herd. As they reach sexual maturity, the frequency of mounting with ejaculate, the performance of riding and the production

To determine the potential as a possible male, it is necessary to establish tests that allow the identification and categorization of males according to their score, taking into account comprehensively both their physical characteristics, such as

Assessments to determine mount efficiency in bucks typically consist of exposing a male to a female in estrus, for a period of time ranging from 15 to 20 minutes to 1 hour in a pen without distractors [51]. During this period, an observer keeps track of the amount of sexual behavior. They are rapid, practical and inexpensive tests that allow identifying the willingness of the male to serve the female and together with this, discard males with unsuitable profiles within a reproductive

In tests of reproductive capacity, motivation is linked to the animal's libido and for this reason some authors recommend the use of more than one female in estrus [49]. Other factors that influence the performance of males in the evaluation of reproductive capacity are the breed of the animal, season of the year, age, the sexual experience they have and the hierarchical position that the male occupies [33]. For the evaluation of sexual behavior in bucks there are different strategies that can be implemented to determine acts of courtship and mating acts. The reaction time test allows us to identify the time it takes for the male to achieve the first mount with ejaculate and thus have an estimate of the libido of the evaluated

The service ability test is one of the most widely used tests. It consists of placing the male before one or several females in heat for a certain period, usually between 15 to 60 minutes in a pen. During this period an observer counts the number of interactions between the male and the female (s), which can be optionally rated or, only indicate the frequency with which the courtship acts, the mounts or the

Observations can be made individually or in groups. Individual observations should be made in the absence of other males, while group observations should take into account that they must be of similar ages to give accuracy to the test, seeking to

carry out at least three tests to estimate service capacity [25, 53, 54].

### *Reproduction in Small Ruminants (Goats) DOI: http://dx.doi.org/10.5772/intechopen.93481*

*Animal Reproduction in Veterinary Medicine*

productivity of the herd [37, 38].

*2.4.1 Cortisol and stress physiology in bucks*

herd or change of habitat [41].

*2.4.2 Social factors and sexual behavior in males*

with the highest sexual activity [49].

management systems around the country [17, 43].

behaviors [42].

identifying that the size of the pen and the size of the herd influences the increase in stress due to clustering, negatively impacting the weight gain of the bucks and the

Ivasere et al. [39] recorded behavioral changes by intensifying production systems and their effect on productive aspects such as nutrition, reproduction and diseases. They observed that the social structure is of great importance in the physiological and ethological development in bucks, modifying the frequency of courtship, copulation and the stress level in bucks grouped in herds of different densities. So far there is little information in the literature about the effect of regrouping previously raised male goats in pairs and regarding how serum cortisol and testosterone concentrations, seminal quality and sexual behavior are affected after such grouping.

Within the management of goats, efforts have been made to develop strategies to improve the quality and efficiency within the herds. At an intensive level, the management carried out ranges from supplying drugs, palpation, semen extraction, and pen cleaning. These management activities, in conjunction with other factors, such as the size of the herd, overcrowding, feeding or the immune system of animals, influence the body's physiological response to various stressful situations [40]. The most common stressors in goat production are mainly those caused by environmental heat and the increase in body temperature, deprivation or lack of access to food or water, as well as modifications in the hierarchical structure of the

Among the responses at the physiological level present in male goats in stressful situations is the secretion of glucocorticoids (GC), which exert a negative feedback effect on the hypothalamic-pituitary-gonadal axis, reducing the synthesis of GnRH and together thereby inhibiting the synthesis of gonadotropins and sex steroid hormones [34, 39]. This endocrine mechanism aims to stimulate the body to respond to stressors, such as loss of appetite, suppression of the immune system, energy mobilization, vasoconstriction, and loss of erection and receptive sexual

The grouping of bucks is a widespread practice mainly in stable and mixed

which guides producers as a key criterion for selecting males [45, 46].

The study of behavior has shown that the establishment of hierarchical ranks and social organization influence sexual behavior that will be exhibited by a male under grouping conditions [44]. This dominance is related in turn to the live weight of the animal and its age, mainly as part of a display of reproductive competition,

By remaining in coexistence conditions, one of the males tends to monopolize access to the females in estrus in order to ensure their reproductive success, being this considered the dominant male [47], which initiates a display of dominance behaviors, such as competition due to access to food, increased physical activity and hoarding of better resting places, while the subordinate male at the hierarchical level initiates evasive or submissive behaviors and sexual behavior is characterized by opportunistic-type strategies [48]. The dominant male is characterized by having a more aggressive behavior compared to the rest of the males and is also the one

Among the activities carried out mainly by the dominant male, the increase in vocalizations, head movements, tapping, lunges and displacement and protection

**80**

of the female in heat (tending) from other males stands out [42], thus reaching inhibit the sexual behavior of subordinate males [36].

According to Mainguy et al. [41], the establishment of the dominance position is accentuated with the secondary sexual characteristics, which is also related to the age and body weight of the animal [50], helping to strengthen the male's hierarchical position and social structure within the herd. As they reach sexual maturity, the frequency of mounting with ejaculate, the performance of riding and the production of semen in dominant bucks compared to subordinate's increases [36].
