C.S. Galina

Behavioural trends affecting oestrus detection in Zebu cattle

Abstract Factors affecting the accuracy of oestrus detection in Zebu cattle following natural or induced oestrus are reviewed. Special reference is given to the social interactions within a herd which affect the signs of oestrus in this type of cattle. Group composition and size affect accuracy in the timing of the observation of overt signs of oestrus with animals often imitating behavioural oesturs. The implications of these findings for the use of artificial insemination in the tropics are discussed.

Some effects of repeated handling and the use of a mask on stress responses in zebu cattle during restraint

The objective of this investigation was to evaluate the effect of repeated handling and the use of a mask on the order of entry, temperament, cortisol concentration and heart and respiratory rates of Brahman cattle during restraint in a squeeze chute. In the first experiment, 18 cows were restrained in the chute for 10min on 19 test-days and blood samples were collected during five of the trials. Habituation to handling was reflected by a decrease in cortisol concentration as the study advanced (P<0.01). In the second experiment, conducted 6 months later, animals were randomly allotted to two groups, alternating the use of a mask over test-days while restraining the cows in the chute for 3min. Respiratory and heart rates were measured at the beginning and end of each 3min trial. A blood sample was also taken at the end of each trial. Respiratory rates decreased while the animals were restrained and this decrease tended to be greater (P=0.09) when the animals were wearing masks (3.06) than when not (2.2breaths/min). Heart rates also decreased and more so for masked animals (10.6beats/min) than for non-masked (5.0, P<0.01). Cortisol values tended to be higher (9.9 versus 4.7ng/ml, P=0.08) when animals were restrained without a mask. Temperament scores were lower (P>0.01) when cows were masked and have a relative high correlation (r=0.58) with flight distance values, (P<0.05). Finally, the order of entrance was found consistent over test-days, (P<0.01). It is concluded that Brahman cattle: (a) habituate to repeat handling in a squeeze chute; (b) are less emotionally reactive when their eyes were covered during this process and (c) establish a repeatable order of entrance to the chute.

The effect of social rank on the physiological response during repeated stressful handling in Zebu cattle (Bos indicus)

Although the order of entry to a handling chute is related to social rank, it is still not clear what the consequences are for Zebu cattle of occupying different ranks when being exposed repeatedly to a stressful handling procedure. Eighteen Brahman cows were observed for 243 h to obtain information on social interactions. From that information, indices of success in displacing other individuals of the herd were calculated to reflect social status of each cow. One week after behavioral observations, the cows were forced 19 times to enter a handling chute where they were palpated and 7 ml of blood was collected from their caudal vein. To have an adrenal activity profile along the experimental period, five blood samples (Days 2, 6, 10, 15, and 19) were chosen for cortisol determination. On each sampling day, the average time in the chute, the order of entry, and a value of entrance consistency were calculated. On average, the high-ranking cows entered the chute before the medium- and low-ranking cows. Medium-ranking cows showed higher consistency when entering the race than high- and low-ranking cows. Low-ranking cows had significantly lower cortisol levels than the other two groups since the second sample (Day 6 in the race), and had higher cortisol levels the first time handled than at subsequent sampling days. It is suggested that low-ranking cows adopt a passive strategy that allows them to have a better control over the stressful event, while high-ranking cows respond with higher cortisol levels perhaps because of the need to become aroused to deal with challenges. It was concluded that the herd (a) habituated to repeat handling in a squeeze chute and (b) low-ranking cows responded with lower cortisol concentration to handling.

Behavioral patterns of Zebu bulls towards cows previously synchronized with prostaglandin F2α

Abstract With the objective of comparing the behavioral activities of synchronized cows in the presence or absence of a bull, 30 Indobrazil cows with a mature corpus luteum, identified by rectal palpation, were injected with 25 mg of prostaglandin F2α (PGF2α) approximately at Day 8 of the cycle for three consecutive cycles. Immediately after each injection, the animals were observed continuously for 100 h during three observation periods. Having established a hierarchy order in the herd, cows were allowed to interact with two mature bulls, one during the first cycle and the other during the second; in the third cycle, they were allowed to interact without the presence of a male. Behavioral activities such as butting, smelling the genital area, mounting, attempting to mount and following were recorded. No differences were detected between observation periods with respect to the accuracy of estrous detection, duration of the estrus period or interval from injection to onset of estrus. Sixty percent of the mounts recorded were initiated by cows high in the hierarchy order. Genital investigation was significantly more frequent when the bulls were present. The intensity of estrous behaviour varied in the same cows in the presence or absence of the bull. Furthermore, 20% of the cows injected three times showed no behavioral estrus. Mounting occurred more frequently at night in the absence of the bulls.

Consequences of different suckling systems for reproductive activity and productivity of cattle in tropical conditions

The late onset of ovarian activity in mature cattle raised under tropical conditions is the major setback impeding a sound reproductive performance needed for the increasing demand of livestock products in the area. The effect of suckling has been circled as one of the most important factors impeding ovarian activity. Farmers in this region have used the most diverse set of management tools to overcome the suckling effect without compromising reproduction, the health of the calf, growth until weaning, milk production and a correct function of the mammary gland.Farmer interventions can be divided in: (1) early weaning (about 1 week of age); (2) weaning at 1, 3 or 5 months; (3) restricted suckling; (4) partial weaning. These systems can be affected by the breed of the animal, the location of the enterprise, infrastructure in the farm, time of the year and system of separation. The advantages and disadvantages of these systems are discussed in this review.

Social order measured in pasture and pen conditions and its relationship to sexual behavior in Brahman ! Bos indicus) cows

Abstract The relation of the social order between cows was determined by recording content and outcome of all agonistic interactions in a herd of 20 non-lactating, non-pregnant Brahman cows ranging from 2–6 years old, under both pasture and yard conditions. The herd was observed at pasture for periods of 1.5 h and under pen conditions for periods of 2 h on the same day. This routine was undertaken every other day from 06.00 to 18.00 between February and June 1995, giving a total observation time of 375 h, after which all cows were given an ear implant of Synchro-mate B (SMB), an estrous synchronization treatment. On the day of implant withdrawal a mature, 5-year-old bull with proven service capacity was placed with the cows. Continuous observation for estrous detection was carried out for 96 h following implant removal. The Kendal rank correlation coefficient was used to determine the relationship between social and sexual variables for the total of 1750 agonistic encounters recorded. The top ranked cow supplanted other animals 225 times. In contrast, the lowest ranked cow never supplanted another animal. Correlation between social order in the yard, in the field, and their sum, ranged from 0.26 to 0.34, with linearity values over 80% for the three variables. Identical values were possible only with respect to the extreme of the ranking scale. Social index values were low and showed little variation, ranging from 0.0 to 0.128. Estrous efficiency expressed as the percentage of SMB treated animals that show estrous was 60%. A low correlation was observed between dominance order and sexual behavior. However, correlation coefficients above 0.9 were observed within the sexual variables such as mounts exhibited, received, number of homosexual participants, or male attention. Our results indicate that dominance order may differ according to the data source (yard, field or their sum), and that there is no relation between social order and sexual behavior.

Reproductive behaviour in bulls raised under tropical and subtropical conditions

The present review describes the behavioral characteristics of bulls raised under tropical and subtropical conditions and emphasizes the difficulties associated with adequately monitoring their performance in the field to predict reproductive potential. Most of the information generated for improving our understanding of bull behavior under range conditions has been generated in Bos taurus bulls. The limited information available in Bos indicus indicates that males searching for cows in estrus display different sexual patterns when compared to B. taurus bulls and a poor selection of a sire utilized in range conditions can have an important impact in cattle production. Screening and selecting [cg1] bulls for desirable reproductive traits and high libido is known to improve the reproductive performance of the herd. The reproductive and genetic potential of a bull is influenced by factors such as management, age, nutrition and problems related to the female such as embryonic death and anestrus. However, behavioral characteristics of bulls when detecting and serving cows in estrus is poorly understood.

Sexual behavior of Zebu cattle (Bos indicus) following estrous induction by Syncro-Mate B, with or without estrogen injection

The effect of estrogen administered with norgestomet implants in the expression of behavioral estrous of Zebu cattle was studied in a herd of 18 cycling Brahman cows, in two trials. In the first and second trials, six different cows were treated with progestagen on successive days. In addition, in the first trial, estrogen injection was applied with the treatment. With the purpose of enhancing mounting behavior in treated and/or non-treated animals, on the third day of each trial, three other cows with an active CL were injected with 25 mg of PGF2alpha. All animals were examined three times a week by rectal ultrasound, and a blood sample was also taken for progesterone analysis. Sexual activity was monitored by a closed-circuit TV from 1500 to 0600 h. Direct observation was carried out from 0900 to 1200 h. A total of 15 cows displayed 36 mounting periods (11 with ovulation). Twenty-five annovulatory estrous periods were observed, 77% supported by large follicles. More cows (66% vs. 16%) showed mounting activity when estradiol valerate was used as part of the progestagen treatment (P=.03). Ovulation rate in response to the effect of norgestomet implant was 16%, independent of treatment. It is concluded that estrogen administered with norgestomet implants increases the expression of behavioral estrous in Bos indicus cattle but does not improve ovulation rate.

Cows treated with Synchromate B may cluster their sexual behaviour independent of follicular growth at the time of oestrus

In order to study the relative influence of social versus hormonal influences on sexual behaviour, three groups were formed from a herd of 16 Brahman cows, two of which groups were synchronized, implanting the second group the day the first had the Synchromate B (SMB) withdrawn. The third group was the untreated control. Cows in the sexually active group (SAG) were subjected to an intensive ultrasound (US) schedule to monitor ovarian activity. Alternatively, US examinations and progesterone (P4) samples were obtained twice weekly starting one week before the SMB implant until one week after the last implant was removed. Twenty mounting series involving 13 cows were observed. All cows in Groups 1 and 2 and 50% of controls displayed mounting behaviour, grouped on two periods. Seven cows showed mounting activity on both periods (8 days apart). Three cows in Group 2 (60%) displayed riding behaviour when the SMB implant was in place. No differences (P=.39) were found between the average size of the major follicle from animals displaying oestrus at the expected time (6.95+/-2.6 mm), and those displaying oestrus outside this period in harmony with induced animals (7.79+/-1.5 mm), nor (P=.71) between treated (7.72+/-2.0 mm) and untreated (7.28+/-2.1 mm) cows. It is concluded that treated and untreated animals, and even cows with an implant in place, may display mounting activity concomitantly with oestrous-induced cows and this behaviour is not driven by follicular size at the time of the expected oestrus. Furthermore, the follicular development suggests that SMB treatment does not impede and may even enhance oestrous response in certain cows when applied together with exogenous estrogens.

Efecto de las Características del reinicio de la actividad ovárica posparto en la eficiencia reproductiva de vacas Holstein en pastoreo

The objective was to evaluate the effect of the characteristics of the onset of the postpartum ovarian activity on the reproductive efficiency of dairy cows....