Functional characteristics of the bovine hypothalamic-pituitary-adrenal axis vary with temperament

A Review of the Effects of Stress on Dairy Cattle Behaviour

In this narrative review, the authors summarise the relationship between stress and behaviour and how dairy cattle cope with stressors. Based on the available literature, the most common stressors in intensive dairy cattle farming, such as pain, disease, heat stress, poor comfort caused by technology, and social stress, are surveyed. The authors describe how these stressors modify the behaviour of dairy cattle, influencing their feeding patterns, social interactions, and overall well-being. Additionally, the review explores the effectiveness of various coping mechanisms employed by dairy cattle to mitigate stress, including physiological adaptations and behavioural responses. This review is a valuable resource for understanding and grading stress in dairy cattle through behavioural reactions. Elucidating the intricate interplay between stressors and behaviour offers insights into potential interventions to improve animal welfare and productivity in dairy farming. Furthermore, this review highlights areas for future research, suggesting avenues for more comprehensive behavioural studies to enhance our understanding of stress management strategies in dairy cattle.

Management of dairy heifers: Can operant conditioning be an effective and feasible tool to decrease stress and ease animals' close contact and handling?

Besides health monitoring, a regular check of dairy heifers' growth rate is desirable, but it is rarely done because procedures that require restraint and handling can be associated with substantial stress for both animals and farmers. Inexperienced heifers, especially if they are highly responsive to humans, may find restraint and handling potentially aversive. This study investigated whether training heifers of different age and responsiveness toward humans (RTH), through operant conditioning, could reduce stress in animals, ease close contact and handling, and be feasible in terms of farmers' effort. We assessed 60 Holstein heifers of 2 age classes (young, n = 29, 291 ± 39 d; old, n = 31, 346 ± 62 d) according to the avoidance distance test and classified them as confident (n = 20), neutral (n = 21), or nonconfident (n = 19). Half of the heifers of each age and RTH class were trained (n = 29), whereas the other half was not (n = 31). The trained heifers were subjected to target training for 8 sessions and positively reinforced with feed to allow being touched on the muzzle, rump, and perineum. If a heifer refused positive reinforcement, the trainer stepped back as negative reinforcement. In the last week of the experiment, the effect of training on the reaction to handling was assessed in all heifers. We measured heart rate, root mean square of successive interbeat interval differences (RMSSD), and fecal cortisol metabolites (FCMet). The presence of behavioral distress signs was recorded as well. The avoidance distance test was performed a second time 24 h after the measuring session. All of the trained heifers, regardless of RTH class, successfully accomplished the target training task in 6 sessions, each spending on average 25.3 s per session. All of the trained heifers allowed touches on the rump and perineum at the end of the fourth session. Training nonconfident heifers required more time compared with the others. Trained heifers showed higher RMSSD than nontrained heifers (14.2 vs. 16.9 ms, respectively), indicating a lower vagal tone, and thus, a slightly lower stress level than nontrained heifers. Training did not lead to differences in HR, FCMet, or presence of stress behavioral signs. Nonconfident heifers had the highest mean baseline FCMet values compared with neutral and confident heifers (38.4 vs. 30.3 vs. 29.1 ng/g, respectively). Nonconfident heifers also showed the lowest value of FCMet 12 h after the measuring session (36.7 vs. 44.6 vs. 49.7 ng/g), likely due to a decreased responsiveness of the adrenal gland to a stressor. The average avoidance distance decreased between the beginning and the end of the experiment, especially for neutral and nonconfident heifers, regardless of whether they were trained or not. These results show how using operant conditioning on some heifers not only decreased their vagal tone, but also reduced the responsiveness to humans of all the animals, trained and not trained; in the latter case, this reduction was through nonassociative learning, such as habituation.

Effect of transportation distance and lairage time on selected behaviors and carcass parameters in zebu cattle-a study using the animal focal sampling method

The objective of this study was to evaluate the effect of the transport distance and lairage time on behavioral indicators of zebu beef cattle in the resting pen of a slaughterhouse using the focal animal technique. Eight lots of male zebu cattle, Nelore, aged approximately 4 years old, weighing on average 500 ± 28.5 kg-1, from different municipalities, transported by land, were evaluated. The lots were grouped into two categories: short distance (> 500 km) and long distance (> 500 km). Five focal animals per evaluated lot were used in each cycle of behavior observation, randomly chosen, and visually identified. The animal focal sampling method was used, with instantaneous recording, every 5 min per animal/h. A video camera was used and placed at a fixed point in the corral. After slaughtering, bruises and carcass pH were evaluated. The respiratory rate (RR) was measured in two moments, 30 min after unloading (RR_I) and 1 h before slaughtering (RR_F); behavioral data were divided into four lairage periods (1st, 2nd, 3rd, and 4th) equally and evaluated as repeated measures over time. The lairage time lowered the behaviors of headbutting (NCHBs), pushing (PsH), mounting (MT), and chasing away (CA), (p = 0.0001), and these behaviors were more evident in animals transported for short distances in the initial resting times, decreasing as they remained in the resting pen. There was effect of distance on the initial and final pH of the carcass, being greater in the short distance (p = 0.047). There was no effect of distance or lairage time on initial or final RR (p > 0.05). In addition, animals transported over long distances showed less carcass injuries, which were observed during post mortem inspection. It is concluded that animals transported over short distances present a greater number of agonistic behaviors, such as NCHBs, MT, PsH, and CA, predisposing to higher rates of bruising during lairage and more accentuated changes in the final pH of the meat.

Temperature and humidity index (THI) affects salivary cortisol (HC) and dehydroepiandrosterone (DHEA) concentrations in growing bulls following stress generated by performance test procedures

The hypothalamus-pituitary-adrenal axis response to a challenge was proposed for genetic selection of robust and resilient animals. As ACTH (adrenocorticotropic hormone) test and hormone measurements in blood may result impractical, it may be useful to measure salivary hormones in response to natural stressors, after an accurate biological validation, to control factors that could contribute to the response. We evaluated whether animal handling during performance test affects salivary HC and DHEA secretion and could be used for selection. We tested the effects of habituation to repeated handling and THI as putative bias. Bull calves (N = 273) undergoing performance test were sampled at 8-9 and 11-13 months (N = 101), 8-9 months (N = 131), or 11-13 months (N = 41). On each test day (D0), calves were isolated, conducted to a squeeze chute and immobilized for 6 min. Saliva samples were collected in the morning after feed administration (T0), and after 6 min immobilization in the squeeze chute (T1) for HC and DHEA measurement. Environmental temperature and relative humidity were recorded every hour from 1:00 h to 24:00 h during the 6 days before the performance test and on D0. Salivary HC and DHEA concentrations were higher in T1 (p < 0.01), although a clear individual positive response to handling could be observed in less than 10% of subjects. The mixed model revealed: (i) HC and HC/DHEA were higher in Young bulls (p < 0.05). (ii) The time of T0 sample collection significantly affected DHEA (p < 0.01) and HC/DHEA (p < 0.05). (iii) THI affected both steroids (p < 0.001) but not HC/DHEA. Spearman correlations suggested that THI weakly affected salivary HC at T0 only (ρ = 0.150, p < 0.01), while moderate statistically significant correlations were found between DHEA and THI at T0 (ρ = 0.316, p < 0.001), and T1 (ρ = 0.353, p < 0.001). Salivary HC and DHEA in response to handling procedures might identify subpopulations of subjects with sensitive HPA axis. Habituation to repeated handling played a role, as the hormone response was lower in older animals. Chronic exposure to high THI had a minor effect on salivary HC visible at T0. A more intense THI effect was observed on salivary DHEA concentrations at both T0 and T1, which should be worth of further investigations.

Influence of handling in corrals on the temperament of different breeds of beef cattle raised in Brazil

The objective of the present study was to verify the effect of handling in corrals on the stress of beef cattle of Nelore, Caracu, and Guzerá breeds through the analysis of the relationship between behavioral traits, growth, and blood parameters. A total of 778 records of entry scores, chute scores, exit scores, flight speed, cortisol, glucose, lactate, live weight, and body condition scores were collected on steers and heifers of the three breeds, born between September and December. The animals came from the Advanced Beef Cattle Research Center of the Animal Science Institute. The variance analyses were performed using the GENMOD procedure. The PROC CORR estimated Spearman correlation coefficients for all traits studied, and the principal components analysis was performed according to the procedure PRINCOMP. Heifers had higher reactivity than steers, with higher behavioral scores and blood parameters. Overall, Caracu individuals demonstrated lower reactivity in comparison to Nelore and Guzerá. However, they presented high stress when they were restrained. The principal component analysis highlighted that behavioral traits and blood parameters were contrasted with growth traits; thus, this analysis can help selectors (livestock farmers) understand the importance of selecting less reactive animals and more easily choose the animals they want to select for breeding. Our results indicate that handling in corrals could be considered a stressful event for bovines. For this reason, measuring blood parameters and behavioral traits can compose necessary decision-making tools regarding changes and adequacies while handling events to reduce stress and consequently improve the herd's reactivity.

Genetic parameters for behavioral and growth traits of Nellore cattle

The growing concern of consumers with the welfare of production animals searches welfare in a production system extremely important; thus, the study of animal temperament is necessary to select less excitable temperament animals resulting in healthy development and fewer accidents. The objective of this study was to estimate genetic parameters for traits related to animal temperament and growth traits of Nellore cattle. In addition to exploring the genetic pattern of these traits through cluster and principal component analysis (PCA), to reveal possible groups of individuals that express less excitable temperament and greater growth. A total of 2,332 measurements from 1,245 male and female Nellore cattle born between 2008 and 2016 were utilized in the study. The (co)variance components were estimated by Bayesian inference using a two-trait animal model. The heritability for temperament score (TS), flight speed (FS), body condition score (BCS), live weight (LW), and hip height (HH) were 0.08, 0.12, 0.06, 0.13, and 0.48, respectively. The genetic correlation between the temperament indicator traits was strong and positive (0.78 ± 0.24). The TS and FS showed a favorable or null genetic correlation with LW, BCS, and HH. The third cluster included animals with low EBV for TS and FS and with high EBV for BCS, LW, and HH. In the PCA, the PC1 was what best evidenced the aim of this study; thus, our findings suggest that we could explore select animals based on cluster 3 and PC1 in breeding programs to select Nellore cattle with less excitable temperament and greater growth.

Mitigation of low pregnancy rate in excitable Nellore cows by administration of GnRH or P4

This research aimed to determine the effect of temperament on reproductive parameters including cortisol and progesterone (P4) in Nellore cows. Additionally, two methods for increasing plasma progesterone (P4) levels in excitable animals to enhance pregnancy rate (P/AI) and reduce pregnancy loss were investigated. In total, 939 cows were subjected to timed artificial insemination (TAI) and divided into three groups: (P4LA; n = 305) 150 mg of injectable long-acting progestogen 7 days after TAI; (GnRH; n = 306), 10 μg of buserelin acetate on day 7 after TAI; control group (CG; n = 328) without hormonal treatment. In 213 cows, randomly chosen from each group, ultrasound evaluations of the preovulatory follicle (Mode B) were performed on the day of insemination and of the corpus luteum (Color Doppler) 7 and 16 days after TAI. Blood samples were obtained from 20% of the 939 animals, randomly chosen from each group, on the day of insemination and after 7 and 16 days to measure cortisol and progesterone, respectively. At the time of insemination, subjective temperament evaluations were performed with the animals being classified as excitable (EXC) or adequate (ADQ). The SAS GLIMMIX procedure was used to compare the pregnancy rate (P/AI) and gestational loss within each temperament for the three experimental groups. Continuous variables were analyzed utilizing SAS PROC MIXED procedure. Cortisol concentration was higher and POF (preovulatory follicle) and CL (corpus luteum) volumes at the time of insemination and 7 days after AI, respectively, were lower in EXC animals than in ADQ. No significant difference was observed between the number of pixels, CL intensity, and plasma concentration of P4, 7 days after TAI. However, 16 days post-insemination, among the animals classified as EXC, higher concentrations of P4 were observed in the GnRH and P4LA groups than in the control. Regarding P4 concentrations, there was a tendency to be lower in animals classified as EXC than in ADQ within the control group (P = 0.06), while rate of blood flow from the CL was lower in EXC animals than in ADQ animals (P = 0.04). Among the ADQ animals, the GnRH and P4LA groups showed a lower CL flow rate than that observed in the control (P = 0.04), 16 days after the TAI. Among EXC animals, a higher pregnancy rate was observed in the GnRH and P4LA groups than in the control group (P = 0.01). In the control group, the pregnancy rate (P/AI) of the ADQ animals was higher than that of the EXC animals (P = 0.05). No statistically significant differences were observed between gestational losses when the treatments or temperaments were compared. In conclusion, the use of GnRH or P4LA, 7 days after insemination, improves pregnancy rates in excitable animals and is a viable alternative to minimize the negative impact of stress and improve reproductive efficiency in beef cattle.

Influence of Excitability Rate on Physiological Responses to Stress in Goats

This study was conducted to determine if excitability score (ES) in goats can influence their physiological responses when subjected to stress. Thirty-six intact male Spanish goats (8-mo-old) were individually weighed and scored for excitability: 1 for calm (13 goats), 2 for moderately excitable (11 goats), and 3 for highly excitable (12 goats). To impose stress, goats were assigned to one of three treatments (TRT) for 90 min: (i) isolation in an open pen with metal grill panels, (ii) isolation in a pen with side panels covered using tarp sheets, and (iii) no isolation (control). Blood samples were collected at 0, 30, 60, and 90 min of isolation and physiological data were analyzed using MIXED procedures in SAS. The data from the two isolation treatments were pooled and compared with that of the control group. Plasma cortisol and non-esterified fatty acid concentrations were the lowest in goats with ES 1 (p < 0.05). Neutrophil−lymphocyte ratios were also the lowest in goats with a calm temperament (p < 0.01). Application of full quadratic model using response surface methodology (PROC RSREG) in SAS revealed that the influence of ES on physiological stress responses over time was not the same between the TRT groups. The results indicate that physiological stress responses are greater in goats with an excitable temperament compared to goats with a calm temperament.

Gaps to Address in Ecological Studies of Temperament and Physiology

Ecology is a diverse field with many researchers interested in drivers and consequences of variability within populations. Two aspects of variability that have been addressed are behavioral and physiological. While these have been shown to separately influence ecological outcomes such as survival, reproductive success and fitness, combined they could better predict within-population variability in survival and fitness. Recently there has been a focus on potential fitness outcomes of consistent behavioral traits that are referred to as personality or temperament (e.g. boldness, sociability, exploration, etc.). Given this recent focus, it is an optimal time to identify areas to supplement in this field, particularly in determining the relationship between temperament and physiological traits. To maximize progress, in this perspective paper we propose that the following two areas be addressed: (1) increased diversity of species, and (2) increased number of physiological processes studied, with an eye toward using more representative and relatively consistent measures across studies. We first highlight information that has been gleaned from species that are frequently studied to determine how animal personality relates to physiology and/or survival/fitness. We then shine a spotlight on important taxa that have been understudied and that can contribute meaningful, complementary information to this area of research. And last, we propose a brief array of physiological processes to relate to temperament, and that can significantly impact fitness, and that may be accessible in field studies.

Effect of Finishing Diet and Lairage Time on Steers Welfare in Uruguay

Simple Summary

The transport and general handling of slaughter animals are associated with a series of events that cause stressful and unfavorable conditions that can compromise animal welfare. All these stressful events start at the farm and end with the death of the animal. In this experiment, we evaluated the effect of two finishing strategies and two contrasting lairage times through the combination of several indicators regarding productivity, physiology, behavior and postmortem variables. Individual temperaments and their impact on welfare and carcass quality were also considered. Animal welfare was not compromised in any diet during the finishing period. Individual temperament had a positive impact on the productivity and on all physiological indicators at different preslaughter stages. For that reason, we consider that it should be given paramount importance when talking about animal welfare. According to our results, with pasture-based animals, without fasting on the farm and after a short time of transportation (3.5 h), a longer preslaughter resting time (15 vs. 3 h) is desirable from the animal welfare perspective. Furthermore, our results suggest that this longer resting period, would also be more convenient from the carcass quality perspective.

Abstract

The objective of this experiment was to evaluate the effect of two different pasture-based finishing strategies and lairage time on steers welfare in Uruguayan conditions. Sixty Hereford (H) and Braford (B) steers were assigned to two different diets for finishing purposes: (D1) native pasture plus corn grain (1% of live weight) (H n = 15, B n = 15) and (D2) high-quality pasture (H n = 15, B n = 15). The average daily gain was registered every 14 days, and temperaments were individually assessed one week before slaughter by three individual tests: crush score, flight time and exit speed, building a multicriterial temperament index (TIndex). Animals were slaughtered the same day in two groups (50% from D1 and 50% from D2 in each group) after traveling for 3.5 h and staying 15 (long lairage) and 3 h (short lairage) in the lairage pens, respectively. The behaviors were observed during lairage, and physiological indicators were used to assess stress at the farm after transport, after lairage and at slaughter. Bruises incidence and final pH were registered at the abattoir as a means of assessing the overall animal welfare. Calmer animals had higher average daily gains with no differences either between diets or between breeds. Calmer animals also had a lower stress response during all preslaughter stages, regardless of the time in lairage. Transport did not imply psychological stress (cortisol) for any slaughter group, but physical stress was evident after transport in both groups through NEFA and CPK increases. Bruise incidences did not differ between lairage groups. The short lairage group did not have enough time to cope with the environment before slaughter, with the consequent deleterious effects on the carcass pH. Animals from the long lairage group had a higher metabolic response shown through NEFA values, but they had enough time to rest and recover overnight, reaching final pH values lower than 5.8, considered the upper limit of the normal range. According to this experiment, with pasture-based animals without fasting on the farm and after 3.5 h of transportation, a resting period of 15 h in lairage should be better than a 3-h one.

Inhibition of prolactin promotes secondary skin follicle activation in cashmere goats

The aim of this study was to investigate the involvement of prolactin (PRL) on development of secondary skin follicles in cashmere goats. Goats were randomly assigned to either a bromocriptine treatment or control group. Samples of cashmere fiber, blood, and skin were collected from all goats after 1 mo. The results indicated that the length, growth rate, and diameter of fibers were not influenced (P > 0.05) by the inhibition of PRL resulting from the treatment with bromocriptine. There was a tendency for increases in total follicle number, primary and secondary follicle numbers, and in the ratio of secondary to primary follicles following treatment with bromocriptine, but these differences were not significant (P > 0.05). The percentage of active secondary follicles in anagen was increased (P < 0.05) in the bromocriptine-treated goats, but there was no effect of treatment on the percentage of active primary follicles. Bromocriptine decreased (P < 0.05) circulating concentrations of PRL and Insulin-like growth factor 1 (IGF1) and increased (P < 0.05) those of melatonin (MT), but there was no effect of this treatment on the serum concentrations of cortisol, growth hormone, tetraiodothyronine, and triiodothyronine. In bromocriptine-treated goats, mRNA expressions of PRL and MT membrane receptor 1a (MTNR1a) were decreased (P < 0.05) and mRNA expression of MT nuclear receptor (RORα) was increased (P < 0.05), but there was no effect of the treatment on expression of long PRL receptor, short PRL receptor, MT membrane receptor 1b and IGF1. It is concluded that inhibition of PRL promotes secondary hair follicle development in the anagen phase, possibly by downregulating MTNR1a and up-regulating RORα gene expression in the skin.

Effects on Synchronization and Reproductive Efficiency of Delaying the Removal of the Intravaginal Progesterone Device by 24 h in the 5d Co-Synch Protocol in Heifers

Simple Summary

Reproductive biotechnologies in beef farms are key issues, such as artificial insemination, fixed-time artificial insemination (FTAI), embryo transfer, and ovum pick up, among others. Artificial insemination takes the first place with these available tools. Thus, science keeps improving hormonal treatments and procedures to optimize pregnancies after insemination. A synchronization protocol commonly used in beef heifers is the 5d Co-synch protocol, which fits better in terms of ovarian synchronization and resulting conception rate. We propose a modification of this protocol, which consists of delaying by 24 h the removal of the intravaginal progesterone device, to decrease the percentage of heifers showing estrus before the date of FTAI. Moreover, this modification will make easier the workload when inseminating herds with heifers and cows at the same time. Based on our results, the protocol 5d Co-synch with the delayed removal of the intravaginal progesterone device fits as well as the original protocol in terms of synchronization and conception rate. Therefore, it can be implemented in the heifers of beef cattle commercial farms.

Abstract

In beef herds, increasing animal welfare, improving reproductive performance and easing animal management are key goals in farm economics. We explored whether delaying the removal of the intravaginal progesterone device by 24 h in heifers synchronized with a 5d Co-synch 72-h protocol could improve reproductive efficiency of fixed-time artificial insemination (FTAI). In experiment 1, we examined the total synchronization rate (TSR) in cycling Holstein heifers. Heifers (13.4 ± 0.69 mo.) were randomly assigned to the standard 5d Co-synch 56-h protocol (5dCo56; n = 10), 5d Co-synch 72-h (5dCo72; n = 17), or the modified 5d Co-synch 72-h protocol, in which removal of the progesterone device was delayed by 24 h (6dCo48; n = 19). In experiment 2, 309 cycling beef heifers on 18 commercial farms were subjected to the 5d Co-synch 72-h or 6-d Co-synch 48-h protocol and conception rate (CR) studied. In experiment 1, the three protocols led no differences on TSRs of 80.0% (5dCo56), 88.2% (5dCo72), and 89.5% (6dCo48). In experiment 2, the CR from the beef heifers, observed during two consecutive reproductive seasons did not differ: 59.7% for 5dCo72 and 62.0% for 6dCo48 (p = 0.907). Therefore, delaying removal by 24 h provides satisfactory results without reducing reproductive efficiency of heifers.

Adrenergic Tone as an Intermediary in the Temperament Syndrome Associated With Flight Speed in Beef Cattle

The temperament of farm animals can influence their resilience to everyday variations within the managed production environment and has been under strong direct and indirect selection during the course of domestication. A prominent objective measure used for assessing temperament in beef cattle is the behavioral flight response to release from confinement in a crush or chute. This behavioral measure, termed flight speed (also known as escape velocity) is associated with physiological processes including body temperature, feeding behavior, growth rate, carcass composition, immune function, and health outcomes. This review examines the functional links between this suite of traits and adrenergic activity of the sympathetic nervous system and the adrenomedullary hormonal system. It is suggested that flight speed is the behavioral aspect of an underlying “flightiness” temperament syndrome, and that elevated adrenergic tone in animals with a high level of flightiness (i.e., flighty animals) tunes physiological activities toward a sustained “fight or flight” defense profile that reduces productivity and the capacity to flourish within the production environment. Nonetheless, despite a common influence of adrenergic tone on this suite of traits, variation in each trait is also influenced by other regulatory pathways and by the capacity of tissues to respond to a range of modulators in addition to adrenergic stimuli. It is suggested that tuning by adrenergic tone is an example of homeorhetic regulation that can help account for the persistent expression of behavioral and somatic traits associated with the flight speed temperament syndrome across the life of the animal. At a population level, temperament may modulate ecological fit within and across generations in the face of environmental variability and change. Associations of flight speed with the psychological affective state of the animal, and implications for welfare are also considered. The review will help advance understanding of the developmental biology and physiological regulation of temperament syndromes.

Relationships between temperament, meat quality, and carcass traits in Nellore cattle1

The aim of this study was to evaluate the relationship between temperament in Nellore bulls with carcass and meat quality traits. In total, 1,400 bulls were studied, and temperament was assessed using two measurements: movement score (MOV) and flight speed test (FS). Both MOV and FS were measured at two time points, with background (MOVb and FSb) temperament measured at yearling age, ~550 d after birth, and the preslaughter (MOVps and FSps) temperament measured at the end of the feedlot period. The change of temperament resulting in an increase or decrease in reactivity was also used to measure meat quality. The traits used to define carcass and meat quality included carcass bruises (BRU), hot carcass weight (HCW, kg), ribeye area (REA, cm2), backfat thickness (BFT, cm), marbling score (MS), meat pH after thawing (pH), presence or absence of dark cutters, color parameters of luminosity (L*), redness (a*) and yellowness (b*), cooking loss (CL, %), and Warner-Bratzler shear force (WBSF, kg). A principal component (PC) analysis was initially applied to the carcass and meat quality traits, followed by logistic regression models and linear mixed models to evaluate the effects of temperament on carcass and meat quality. The risks of carcass bruises and dark cutters did not differ as a function of any temperament trait (P > 0.05). In turn, animals classified as high MOVb (reactive) had lower PC3 values (P = 0.05), CL (P = 0.02), and tended to have lower MS (P = 0.08). In addition, animals classified as high FSb (faster and reactive cattle) produced carcasses with smaller REA (P < 0.01), higher meat pH (P < 0.01), lower color gradients (L*, P = 0.04; b*, P < 0.01), and lower PC1 and PC4 scores (P < 0.01) when compared with the low FSb class. For preslaughter temperament, high MOVps was related to lower color a* (P = 0.04), whereas high FSps was related to lower HCW, MS, and PC2 (P < 0.01) than the calmer ones (low FSps). The reduction in MOV was related to more tender meat, and the reduction in FS to heavier carcass and brighter meat. We conclude that excitable temperament in Nellore cattle may have negative effects in some of the carcass and meat quality attributes assessed, mainly those related to muscle deposition on carcass and color gradients. Measurement of temperament before the cattle entered the feedlot was a better predictor of carcass and meat quality traits, compared with temperament assessment at the end of the feeding period.

Plasma estradiol-17β, cortisol, and insulin concentrations and serum biochemical parameters surrounding puberty in Japanese Black beef bulls with normal and abnormal semen

The associations of semen abnormalities with circulating hormones (estrogens, glucocorticoid, insulin) and common biochemical parameters are unclear in beef bulls. We compared plasma concentrations of estradiol-17β, cortisol, and insulin and serum biochemical parameters surrounding puberty in Japanese Black beef bulls (n = 96) with normal post-thaw or abnormal semen (fresh and frozen). Blood samples were collected monthly from 4 to 24 months of age (n = 50) for the assays of plasma estradiol, cortisol, and insulin and every 3 months from 6 to 21 months of age (n = 92) for the serum biochemical analyses. Semen was collected weekly from 12 months until at least 18 months of age. Fresh semen was evaluated for semen volume, sperm progressive motility, concentrations, and morphological defects. The normal fresh semen was frozen by a standard method and examined for post-thaw sperm motility and fertility, which were evaluated for rates of transferable embryos. Bulls were classified as having either normal fresh semen or abnormal fresh semen (when at least one of the above test items was abnormal for 6 months). The normal fresh semen was categorized as having either normal post-thaw semen or low fertility post-thaw semen. The abnormal fresh semen was categorized as having sperm morphological defects, low motility, or morphological defects plus low motility. Plasma cortisol concentrations in the abnormal fresh semen group were higher than those of the normal fresh semen group (p < 0.0001). Plasma estradiol-17β and insulin concentrations in the low-fertility post-thaw semen group were lower than those of the normal post-thaw semen group (p < 0.0001). Serum aspartate aminotransferase and magnesium concentrations were greater for the abnormal fresh semen group vs. the normal fresh semen group (p < 0.005). These results suggest that fresh semen abnormality in pubertal beef bulls might be associated with increased circulating aspartate aminotransferase, magnesium and cortisol. Low-fertility post-thaw semen could have been involved with the lower peripheral estradiol and insulin levels in beef bulls.

The Influence of Temperament on Body Temperature Response to Handling in Angus Cattle

Simple Summary

Understanding animal responses to stressful stimuli is a fundamental aspect to evaluating animal welfare. Stress-induced hyperthermia (SIH) is a term used to describe a short-term increase in body temperature that occurs in response to stressful stimuli. Recently there has been increasing interest in SIH as a physiological measure of psychological stress in livestock species. Previously, studies have suggested that cattle with more excitable temperaments exhibit an increased stress response. This study evaluated the influence of temperament on SIH, during a standardized handling procedure in Bos taurus cattle. In this study, body temperature increased, regardless of sex or temperament traits, characterizing SIH. Nevertheless, both flight speed (FS) and crush score (CS) were associated with an elevated rectal temperature (T_REC) 30 min prior to the handling procedure, and this continued from the start of handling (T0) to 10 min post-handling (T10). The results from this study suggest that temperament may be related to variation in SIH in cattle during handling. Understanding the variation in behavioral and physiological response to stressful events may enable the development of new measures for genetic selection in cattle.

Abstract

Previous studies have indicated that cattle with more excitable temperaments exhibit an increased stress response. The objective of this study was to investigate the relationship between temperament traits, handling, and stress-induced hyperthermia (SIH) in beef cattle. Rectal temperatures (T_REC, °C) of 60 purebred Angus cattle (30 heifers, 30 steers; 235.2 ± 5.11 kg) were recorded at 20 s intervals from 30 min prior to handling until two hours post handling. All cattle were exposed to a standardized handling procedure consisting of (i) being restrained in a weighing box for 30 s; (ii) being held within the crush for 30 s; and then (iii) being restrained in a head bail for 60 s. Cattle temperaments were evaluated via three traits: (1) agitometer score (AG); (2) crush score (CS); and (3) flight speed (FS) during the handling procedure. Agitometer scores and FS measures were used to describe an AG category (AG_CAT) and an FS category (FS_CAT) that were used to classify animals into three temperament categories: 1, calm; 2, intermediate; and 3, temperamental. Pearson’s correlation coefficients were used to evaluate the associations between (i) AG, CS, FS, and T_REC 30 min prior to entry into the weighing box (T-30) and then at 1 min intervals between time of entry into the weighing box (T0) until 10 min post-weighing (T10); and (ii) the relationship between AG, CS, and FS. The relationship between T_REC and temperament traits over the 2.5 h were modeled by using a first-order autoregressive repeated measures model. Flight speed had strong to moderate associations with T_REC at T-30 (r ≥ 0.37; p ≤ 0.006) and between T0 and T10 (r ≥ 0.36; p ≤ 0.01). There were moderate associations amongst T_REC between T0 and T10 and CS (r ≥ 0.31; p ≤ 0.01). A weak relationship existed with CS (r = 0.16; p = 0.16). There were no associations between AG and T_REC at T-30 (r ≥ −0.15; p = 0.84) or between T0 and T10 (r ≤ 0.04; p ≥ 0.4). Rectal temperature, irrespective of sex and temperament traits, was influenced by time (p < 0.0001), and maximum T_REC (39.3 ± 0.04 °C) occurred between 4 and 5.7 min after entry into the weighing box. In addition, CS (p = 0.007) influenced T_REC in these cattle. There were also time × temperament trait × sex interactions with the CS (p = 0.0003) and FS_CAT (p = 0.043) categories; however, time × temperament trait interactions were not statistically significant. Results from this study suggest that cattle with excitable temperaments, as evaluated by FS and CS, have a greater increase in T_REC. In addition, these results suggest that a relationship exists between basal T_REC and FS and CS. Together, these results highlight that temperament, as assessed by FS and CS, influences both basal T_REC and the peak temperature recorded following handling but does not influence the magnitude of change in T_REC post handling.

Flight speed as an indicator of Zebu cattle growth performance and suitability to the feedlot environment

Context Studies assessing the relationship between cattle reactivity and growth performance, as well as suitability to the feedlot, in Zebu cattle are limited. Based on previous studies using Bos Taurus cattle, it is expected that reactivity measured at weaning could be used as a predictor of feedlot performance, and that cattle with greater flight speed (FS) would have reduced average daily gain (ADG). Aims The aims of this study were to (1) determine if FS (m/s) measured before entry into the feedlot could be used as a predictor of cattle performance, (2) evaluate the consistency of FS over time, and (3) determine when FS should be measured to best predict animal suitability to the feedlot. Methods A total of 54 Nellore and 40 Guzerat calves were assessed by using FS, which was collected at the time of (FS0) and 1 week after weaning (FS1), as well as on Day 28 (FS28), 56 (FS56) and 168 (FS168) after entry into the feedlot, and a FS average was calculated using FS28, FS56 and FS168 (FS28–168). Performance using ADG (kg/calf.day) was calculated for each animal over three periods: ADG1–28, ADG28–168 and ADG1–168. Bunk attendance (min/calf.day) was recorded over a 173-day feeding period. Key results The ADG28–168 was reduced by 0.14 kg/calf.day for each unit increase in FS0 (P &lt; 0.05). Both ADG28–168 and ADG1–168 were reduced by 0.02 kg/calf.day for each unit increase in FS1 (P ≤ 0.01), but neither FS0 nor FS1 was associated with ADG1–28 (P &gt; 0.10). A significant increase was observed between FS1 and FS28 (P &lt; 0.01), followed by a reduction in FS56 (P &lt; 0.01) and FS168 (P &lt; 0.01). Conclusion FS measured at or within 1 week of weaning has the potential to be used as an indicator of feedlot growth performance in Nellore and Guzerat cattle. Implications Although our results do not indicate the efficacy of FS as a predictor of early suitability of cattle to the feedlot, it does have the potential to support its recommendation as an indicator of overall feedlot growth performance in Nellore and Guzerat breeds.

The development of an immunoassay to measure immunoglobulin A in Asian elephant feces, saliva, urine and serum as a potential biomarker of well-being

Additional measures of well-being would be beneficial to the management of a variety of species in human care, including elephants. Immunoglobulin A (IgA) is an immune protein associated with pathogen defense, which has been demonstrated to decrease during times of stress, and increase in response to positive stimuli. This paper describes the development and validation of an enzyme immunoassay (EIA) for the quantification of Asian elephant (Elephas maximus) IgA in feces, saliva, urine, and serum. Samples were collected weekly from four females for 6 months to assess IgA and glucocorticoid (GC) concentrations, establish relationships between these two biomarkers, and determine variability in IgA within and between individuals, and across sample types. IgA was quantified in all four sample types, although urinary concentrations were low and sometimes undetectable in individual samples. Concentrations were highly variable within and between individuals, with fecal, salivary and serum IgA, and fecal, salivary and urinary GCs all differing significantly across individuals. Contrary to previous findings, IgA and GC were generally not correlated. Serum IgA was less variable within individuals, with the exception of one female that experienced a brief illness during the study. However, marked inter-individual differences were still apparent. When data from all individuals were combined, fecal IgA was significantly predicted by salivary and urinary IgA; however, this relationship did not hold when individuals were analyzed separately. Analysis of a fifth female that exhibited a more severe systemic illness demonstrated clear increases in fecal IgA and GC, suggesting these may also be useful health biomarkers. Further investigation is needed to determine what sample type is most reflective of biological state in elephants, and how IgA concentrations are associated with health and positive and negative welfare states. Based on observed variability, a longitudinal approach likely will be necessary to use IgA as a measure of well-being.

Stress-Induced Immunomodulation in Low and High Reactive Sheep

Simple Summary

Proper functioning of the immune system is fundamental to maintain animal health; however, several factors can modulate an animal’s immune system, including stress. Farm animals can experience multiple stressors throughout their lifetime, therefore there is a need to know how stress can impact their immune response. Moreover, temperament can affect how an animal responds to a stressor, both behaviorally and physiologically. CarLA is a protective antigen against gastrointestinal nematodes; we wanted to evaluate if there was a relationship between stress and temperament on the CarLA response in ewes. We found that both a 0.5 h and 23 h stressor appeared to have an immunosuppressive effect on CarLA IgA but not total IgA concentrations in ewes and there was some indication that CarLA concentrations were also affected by ewe temperament. More research is needed to understand what these immunosuppressive effects of stress on CarLA IgA concentrations mean in relation to sheep immunity to parasitism using farm relevant stressors.

Abstract

The objective of this study was to investigate the relationship between stress and temperament on the humoral immune response of ewes. Eighty ewes were allocated to one of four treatment groups in a 2 × 2 factorial design (n = 20 ewes/treatment): low (LR) and high (HR) reactive ewes were either exposed to no stress (CON) or were visually isolated (STRESS). Ewes remained in treatment pens for 23 h: heart rate was measured continuously, and saliva samples were collected prior to testing and at 0.5 h and 23 h for measurement of cortisol, CarLA IgA and total IgA concentrations. After the first 0.5 h, heart rate was elevated, and cortisol concentrations tended to be higher, whereas CarLa IgA concentrations were lower in STRESS than CON ewes. Similarly, after 23 h, cortisol concentrations remained elevated and CarLA IgA concentrations remained lower in STRESS than CON ewes. Interestingly, total IgA concentrations were not influenced by a 0.5 h or 23 h stressor. Overall, CarLA IgA concentrations were lower in HR than LR ewes at 0.5 h, but there was no significant stress × temperament interaction. Therefore, stress appears to have an immunosuppressive effect on CarLA IgA but not total IgA concentrations in ewes.

Thermoregulatory responses and reproductive traits in composite beef bulls raised in a tropical climate

It is believed that increased livestock production is limited by tropical climate. Thermal imbalance in bulls can lead to hyperthermia and alter testicular metabolism, causing subfertility or infertility. Therefore, the thermoregulation of composite Canchim bulls (5/8 Charolais × 3/8 Zebu) raised in tropical climate as well as their consequences in the physiological, hematological, hormonal, and andrological parameters were evaluated monthly. The bulls (n = 18; 30.0 ± 1.5 months; 503.8 ± 23.0 kg) were kept on pasture, in a single group, from August 2015 to March 2016, comprising the winter, spring, and summer seasons. Biometeorological variables were continuously monitored, and the Temperature and Humidity Index (THI) was calculated. A greater thermal challenge occurred in spring and summer (THI ≥ 72.0). Nevertheless, the bulls exhibited normothermia (38.6 to 38.9 °C) in these seasons. The cortisol did not vary between seasons (7.0 vs. 8.7 vs. 6.8 ng/mL; P > 0.05) and remained within the physiological patterns. Independent of the seasons, stress leukogram was also not observed, refuting the incidence of acute or chronic thermal stress. It is noteworthy that T3 and testosterone increased (P < 0.0001, P < 0.05) in spring and summer, the time that coincides with the breeding season, when there is increased metabolic requirement from the bulls. The progressive thermal challenge increase did not affect the scrotal thermoregulatory capacity, and in general, scrotal temperature remained at 5.2 °C below the internal body temperature. In summer, there was a 5% reduction in the minor sperm defects (P < 0.05) and DNA fragmentation in 2.4% of spermatozoa, a compatible value for high fertility bulls. The results show that the studied composite bulls can be considered as climatically adapted and constitute a viable alternative to be used in production systems in a tropical climate, even if the breeding seasons occur during the most critical thermal condition periods of the year.

Personality is associated with feeding behavior and performance in dairy calves

Performance varies considerably at weaning, perhaps in part because it is associated with the personality traits of the animals. Our objective was to identify calf personality traits using standardized tests and determine whether these were associated with measures of feeding behavior and performance. Fifty-six dairy calves were housed in 7 groups of 8 calves each with access to an automated milk feeder and ad libitum access to water, starter, and hay. We measured starter DMI and the number of unrewarded visits to the automated milk feeder during each of 4 periods: prestep (full milk allowance; 7-41 d of age), step (milk allowance reduced to 50%; 42-50 d of age), weaning (51-54 d of age), and postweaning (55-68 d of age). At 27 and 76 d of age, each calf was subjected to 3 novelty tests: novel environment (30 min), human approach (10 min with an unknown stationary human), and novel object (15 min with a black 140-L bucket). During each of the tests, 7 behaviors were scored: latency to touch and duration of touching the human or object, duration of attentive behavior toward the human or object, number of vocalizations, number of quadrants crossed as a measure of activity, and duration of inactivity, exploration, and playing. Data were averaged across ages and then across tests. Principal component analysis revealed 3 factors (interactive, exploratory-active, and vocal-inactive) that together explained 73% of the variance. Calves that were more exploratory-active began to consume starter at an earlier age and showed greater starter dry matter intake during all experimental periods and greater overall average daily gain. Calves that were more interactive and vocal-inactive had more unrewarded visits to the milk feeder during initial milk reduction. We conclude that personality traits are associated with feeding behavior and performance around weaning.

Predictors of beef calf temperament at weaning and its impact on temperament at breeding and reproductive performance

Two experiments were conducted to determine (i) factors influencing calf temperament at weaning, (ii) association between heifer-calf temperament at weaning and temperament at breeding and (iii) effect of heifer-calf temperament on pregnancy rate per artificial insemination (P/AI). In experiment 1, beef cows and their calves (n = 285) from three farms were used. Sire docility estimated progeny difference (EPD) score, birth type (normal or assisted), calf gender, calf behaviour (during 1st 4 weeks) and calf health status (until weaning) were recorded. Cows and calves were assigned a temperament score (0-calm; 1-excitable), and all cows were given a body condition score (BCS, 1-9; 1-emaciated; 9-obese) at weaning. Calf's illness (p < .05), low sire docility EPD score (p < .05), altered gait (p < .05), altered resting behaviour (p < .01), reduced/no play behaviour (p < .05) and cow excitable temperament (p < .001) increased calf excitable temperament at weaning. In experiment 2, replacement heifer-calves (n = 758) from 12 farms were assigned a temperament score at weaning and later at breeding. Blood from 40 calves at weaning and 31 heifers at initiation of synchronization (same animals) was collected by coccygeal venipuncture for determination of circulating cortisol and substance P concentrations. Heifers were assigned a BCS and reproductive tract score (RTS, 1-5; 1-immature, acyclic; 5-mature, cyclic), synchronized for fixed time AI, observed for oestrus and were artificially inseminated. Cortisol concentrations were increased in excitable heifer-calves compared to calm heifer-calves at weaning (p < .05), and substance P was increased in excitable compared to calm females both at weaning and breeding (p < .05). Low sire EPD docility score (p < .01), heifer-calf excitable temperament at weaning increased excitable temperament at breeding (p < .01). Controlling for BCS categories (p < .01), oestrous expression (p < .0001) and temperament at breeding by oestrous expression (p < .05), the calf's excitable temperament at weaning (p < .001) reduced P/AI (Calm, 62.7 (244/389) vs. Excitable, 53.4% (197/369); p < .01). In conclusion, selection of docile cows and sires with greater docility EPD score should be given consideration to reduce calf excitement. Temperament in beef female can be detected earlier in their life and could be used as a tool in the selection process and to improve their performances.

Role of the stress-associated chemicals norepinephrine, epinephrine and substance P in dispersal of Mannheimia haemolytica from biofilms

Bovine respiratory disease (BRD) is a major problem for the cattle industry that is triggered by various environmental stressors, pathogens and host responses. Mannheimia hemolytica, an important bacterial component of BRD, are present within the nasopharayngeal region of normal calves as commensal biofilm communities. However, following stress there are changes in the nasopharyngeal microenvironment that triggers the transition of the commensal M. haemolytica into a pulmonary pathogen. The factors responsible for this transition in- vivo are unknown. In this study we developed an in-vitro biofilm model and investigated the effect of three stress- related compounds: norepinephrine (NE), epinephrine (E), and substance P (SP) on M. haemolytica biofilms. Biofilm formation was demonstrated for 3 bovine nasal isolates of M. haemolytica by growing them in basal culture media, basal media with additional glucose, and basal media with a reduced pH. Increased glucose enhanced biofilm biomass for 2/3 isolates, but acidic media did not increase biofilm biomass when compared to biofilm biomass in basal media. When the biofilm was exposed to NE, E and SP, there was a dispersal of the biofilm which was most effective with E, followed by NE, and SP being the least effective. Using high - throughput scanning electron microscopy and confocal-imaging we confirmed our experimental data that treatment with NE, E and SP cause dispersion of M.haemolytica from biofilms.

Effects of supplemental calcium salts of palm oil and chromium-propionate on insulin sensitivity and productive and reproductive traits of mid- to late-lactating Holstein × Gir dairy cows consuming excessive energy

This experiment compared insulin sensitivity, milk production, and reproductive outcomes in dairy cows consuming excessive energy during mid to late lactation and receiving in a 2 × 2 factorial design (1) concentrate based on ground corn (CRN; n = 20) or including 8% (DM basis) of Ca salts of palm oil (CSPO; n = 20), and (2) supplemented (n = 20) or not (n = 20) with 2.5 g/d of Cr-propionate. During the experiment (d 0-203), 40 multiparous, nonpregnant, lactating 3/4 Holstein × 1/4 Gir cows (initial days in milk = 81 ± 2; mean ± SE) were offered corn silage for ad libitum consumption, and individually received concentrate formulated to allow diets to provide 160% of their daily net energy for lactation requirements. From d -15 to 203, milk production was recorded daily, blood samples collected weekly, and cow body weight (BW) and body condition score (BCS) recorded on d 0 and 203. For dry matter intake evaluation, cows from both treatments were randomly divided in 5 groups of 8 cows each, and allocated to 8 individual feeding stations for 3 d. Intake was evaluated 6 times/group. Glucose tolerance tests (GTT; 0.5 g of glucose/kg of BW) were performed on d -3, 100, and 200. Follicle aspiration for in vitro embryo production was performed via transvaginal ovum pick-up on d -1, 98, and 198. Mean DMI, net energy for lactation intake, as well as BW and BCS change were similar across treatments. On average, cows gained 40 kg of BW and 0.49 BCS during the experiment. Within weekly blood samples, CRN cows had lower serum concentrations of glucose, insulin, fatty acids, and insulin-to-glucose ratio compared with CSPO cows, suggesting increased insulin sensitivity in CRN cows. During the GTT, insulin-sensitivity traits were also greater in CRN versus CSPO cows. Supplemental Cr-propionate resulted in lower serum insulin concentrations and insulin-to-glucose ratio within CRN cows only, indicating that Cr-propionate improved basal insulin sensitivity in CRN but not in CSPO cows. During the GTT, however, Cr-propionate supplementation reduced hyperinsulinemia and insulin-to-glucose ratio across CSPO and CRN cows. Milk production, as well as number of viable oocytes collected and embryos produced within each aspiration, were not affected by treatments. Hence, replacing corn by Ca salts of palm oil in the concentrate did not improve insulin sensitivity in Holstein × Gir dairy cows consuming excessive energy during mid to late lactation, whereas Cr-supplementation was effective in improving basal insulin sensitivity in cows not receiving Ca salts of palm oil.

Divergent temperaments are associated with beef tenderness and the inhibitory activity of calpastatin

Ninety-six feedlot-finished Nellore steers were used to verify the relationship between temperament indicators and meat tenderization. Temperament index (TI), chute score (CS), and average of exit velocity (EV) with CS (AT) presented low positive correlations (P≤0.05) with shear force, either at 2 or 16days postmortem (WBSF-16). The rectal temperature was consistently correlated with temperament indicators (TI, CS, and AT) and WBSF-16. Two groups (n=12) representing the most tender (39.2±4.9N) and most tough meat (94.1±11.8N), based on WBSF-16, were compared for temperament, and calpastatin activity (CASTa) was determined 48h postmortem. The tender group presented lower EV, TI, and AT (P≤0.05). The tender group exhibited lower (P≤0.05) CASTa in the triceps brachii muscle, but there was no difference in CASTa in the longissimus lumborum muscle between WBSF groups. Meat tenderness and inhibitory activity of calpastatin may be associated with divergent temperament indices in zebu cattle.

Farm to abattoir conditions, animal factors and their subsequent effects on cattle behavioural responses and beef quality - A review

The current review seeks to highlight the concerns that have been raised on pre-slaughter stress, contributing factors and its consequent effects on cattle behavioural responses and the quality of beef; inter-linking the activities involved from birth to slaughter. Such information is crucial in light of the consumer concerns on overall animal welfare, quality of meat and food security. Slaughter animals are exposed to different conditions during production and transportation to abattoirs on a daily basis. However; the majority of studies that have been done previously singled out different environments in the meat production chain, while conclusions have been made that the welfare of slaughter animals and the quality of meat harvested from them is dependent on the whole chain. Behaviour is a critical component used to evaluate the animals' wellbeing and it has been reported to have an effect on product quality. Apart from the influence of on-farm, transportation and abattoir conditions, the genetic background of the animal also affects how it perceives and responds to certain encounters. Stress activates the animals' hypothalamic-pituitary-adrenal activity, triggering release of various stress hormones such as catecholamines and cortisol, thus glycogen depletion prior slaughter, elevated ultimate pH and poor muscle-meat conversion. Pre-slaughter stress sometimes results to cattle attaining bruises, resulting to the affected parts of the carcass being trimmed and condemned for human consumption, downgrading of the carcass and thus profit losses.

Gene polymorphisms associated with temperament

When individuals are exposed to stressful environmental challenges, the response varies widely in one or more of three components: psychology, behavior and physiology. This variability among individuals can be defined as temperament. In recent years, an increasing large body of evidence suggests that the dimensions of temperament, as well as personality, psychological disorders and behavioral traits, are influenced by genetic factors, and much of the variation appears to involve variation in genes or gene polymorphisms in the hypothalamic-pituitary-adrenocortical (HPA) axis and the behavior-controlling neurotransmitter networks. Here, we review our current understanding of the probabilistic impact of a number of candidate gene polymorphisms that control temperament, psychological disorders and behavioral traits in animals and human, including the gene polymorphisms related to corticotrophin-releasing hormone (CRH) production and adrenal cortisol production involved in the HPA axis, and a large number of gene polymorphisms in the dopaminergic and serotonergic neurotransmitter networks. It will very likely to assist in diagnosis and treatment of human relevant disorders, and provide useful contributions to our understanding of evolution, welfare and conservation, for animals in the wild and in production systems. Additionally, investigations of gene-gene and gene-environment complex interactions in humans and animals need further clear illustration.

Prenatal transportation stress alters temperament and serum cortisol concentrations in suckling Brahman calves

This experiment examined the relationship between prenatal stress and subsequent calf temperament through weaning. The prenatal stressor used was repeated transportation of pregnant Brahman cows for 2 h at 60 ± 5, 80 ± 5, 100 ± 5, 120 ± 5, and 140 ± 5 d of gestation. Prenatally stressed calves ( = 41) were compared with controls ( = 44; dams did not undergo transportation during pregnancy) from 2 wk of age until weaning (average age at weaning = 174.8 ± 1.3 d). Temperament was defined by pen score (PS; 1 = calm and 5 = excitable), exit velocity (EV; m/sec), and temperament score (TS; (PS + EV)/2) and was recorded for each calf on d -168, -140, -112, -84, -56, -28, and 0 relative to weaning (d 0 = weaning). Cortisol concentrations were determined in serum samples obtained on d -168, -140, -28, and 0 relative to weaning. Birth weight and weaning weight were not different between treatment groups ( > 0.1). Pen score was greater ( = 0.03) in prenatally stressed calves (2.84 ± 0.21) relative to controls (2.31 ± 0.21). Exit velocity was greater ( < 0.01) in prenatally stressed calves (2.1 ± 0.14 m/sec) than in controls (1.61 ± 0.14 m/sec). Exit velocity was affected by a treatment × calf sex interaction ( = 0.04) and was greater in prenatally stressed females. Exit velocity was also affected by day ( < 0.0001). Temperament score was greater ( = 0.01) in prenatally stressed calves (2.45 ± 0.16) than in controls (1.95 ± 0.16). Temperament score was affected by day ( < 0.01). Basal cortisol concentrations were greater ( = 0.04) in prenatally stressed calves (15.87 ± 1.04 ng/mL) than in controls (13.42 ± 1.03 ng/mL). Basal cortisol concentrations were greater ( < 0.01) in females (16.61 ± 1.06 ng/mL) than in males (12.68 ± 1.02 ng/mL). Cortisol concentrations were positively correlated ( < 0.01) with PS ( = 0.55, < 0.01), EV ( = 0.4, < 0.01), and TS ( = 0.55, < 0.01). Overall, suckling Brahman calves that were prenatally stressed were more temperamental and had greater circulating serum concentrations of cortisol than control calves.

Salmonella Typhimurium and Multidirectional Communication in the Gut

The mammalian digestive tract is home to trillions of microbes, including bacteria, archaea, protozoa, fungi, and viruses. In monogastric mammals the stomach and small intestine harbor diverse bacterial populations but are typically less populated than the colon. The gut bacterial community (microbiota hereafter) varies widely among different host species and individuals within a species. It is influenced by season of the year, age of the host, stress and disease. Ideally, the host and microbiota benefit each other. The host provides nutrients to the microbiota and the microbiota assists the host with digestion and nutrient metabolism. The resident microbiota competes with pathogens for space and nutrients and, through this competition, protects the host in a phenomenon called colonization resistance. The microbiota participates in development of the host immune system, particularly regulation of autoimmunity and mucosal immune response. The microbiota also shapes gut–brain communication and host responses to stress; and, indeed, the microbiota is a newly recognized endocrine organ within mammalian hosts. Salmonella enterica serovar Typhimurium (S. Typhimurium hereafter) is a food-borne pathogen which adapts to and alters the gastrointestinal (GI) environment. In the GI tract, S. Typhimurium competes with the microbiota for nutrients and overcomes colonization resistance to establish infection. To do this, S. Typhimurium uses multiple defense mechanisms to resist environmental stressors, like the acidic pH of the stomach, and virulence mechanisms which allow it to invade the intestinal epithelium and disseminate throughout the host. To coordinate gene expression and disrupt signaling within the microbiota and between host and microbiota, S. Typhimurium employs its own chemical signaling and may regulate host hormone metabolism. This review will discuss the multidirectional interaction between S. Typhimurium, host and microbiota as well as mechanisms that allow S. Typhimurium to succeed in the gut.

Adrenocortical Expression Profiling of Cattle with Distinct Juvenile Temperament Types

Temperament affects ease of handling, animal welfare, and economically important production traits in cattle. The use of gene expression profiles as molecular traits provides a novel means of gaining insight into behavioural genetics. In this study, differences in adrenocortical expression profiles between 60 F₂ cows (Charolais × German Holstein) of distinct temperament types were analysed. The cows were assessed in a novel-human test at an age of 90 days. Most of the adrenal cortex transcripts which were differentially expressed (FDR <0.05) were found between temperament types of 'fearful/neophobic-alert' and all other temperament types. These transcripts belong to several biological functions like NRF2-mediated oxidative stress response, Glucocorticoid Receptor Signalling and Complement System. Overall, the present study provides new insight into transcriptional differences in the adrenal cortex between cows of distinct temperament types. Genetic regulations of such molecular traits facilitate uncovering positional and functional gene candidates for temperament type in cattle.

Impacts of temperament on Nellore cattle: physiological responses, feedlot performance, and carcass characteristics

Forty-four feedlot-finished Nellore cattle were used to evaluate the impacts of temperament on performance, meat and carcass traits, and serum concentrations of hormones, proteins, enzymes, and immunoglobulins. Individual temperament was assessed at feedlot entry (d 0), 67 d, and 109 d, utilizing chute score (CS; 5-point scale) and exit velocity (EV). Temperament scores were calculated averaging CS and EV scores, and cattle were subsequently classified according to their temperament (an average of ≤3 = adequate temperament [ADQ], or an average of >3 = excitable temperament [EXC]). At the end of the experiment (d 109), all 44 animals were slaughtered, and 16 were randomly selected for final empty body weight (EBW) estimation. Blood samples were collected at 0, 67, and 109 d and analyzed for serum variables (cortisol, insulin, haptoglobin, total protein, lactate, creatinine kinase [CK], lactate dehydrogenase [LDH], and IgA). The incidence of carcass bruises was verified immediately after the hide was removed. Carcass pH was obtained at 0 and 24 h postmortem. Samples of the LM were collected for meat quality analyses. Cattle classified as ADQ had greater final BW ( = 0.03), final EBW ( = 0.02), metabolic weight ( = 0.03), ADG ( = 0.02), feed efficiency ( = 0.03), HCW ( = 0.02), cold carcass weight ( = 0.02), and LM area ( < 0.01) compared to that of the EXC cohorts. Cattle classified as ADQ tended to have a lower percentage of cooler shrink ( = 0.06) compared to that of EXC cattle. No temperament effects were detected for initial BW ( = 0.70), DMI ( = 0.14), cold dressing percentage ( = 0.98), or backfat thickness ( = 0.29). Cattle classified as ADQ had greater marbling ( = 0.02) and meat fat content ( = 0.05) compared with that of EXC cattle. No temperament effects ( > 0.05) were detected for unsaturated fatty acid (UFA), SFA, MUFA, PUFA, and n-6:n-3 ratio. For blood parameters, EXC cattle had greater values of cortisol ( = 0.04) and haptoglobin ( = 0.05) and tended ( = 0.06) to have reduced serum insulin concentration compared with ADQ cattle. Both temperament groups had similar serum concentrations of IgA ( = 0.25) and total protein ( = 0.84). Cattle classified as EXC presented greater amounts ( = 0.05) of carcass bruises. In conclusion, an EXC temperament impaired feedlot performance, carcass characteristics, and meat quality traits in finishing Nellore cattle.

Hypothalamic-pituitary-adrenal and cardiac autonomic responses to transrectal examination differ with behavioral reactivity in dairy cows

Behavior, hypothalamic-pituitary-adrenal axis, and cardiac autonomic nervous system (ANS) activity were evaluated in response to transrectal examination in nonlactating Holstein-Friesian cows with different behavioral reactivity. According to behavioral reactions shown to the procedure of fixing the heart rate (HR) monitors, the 20 cows with the highest and the 20 cows with the lowest behavioral reactivity were involved in the study (high responder, n=20; and low responder, n=20, respectively). Activity of the ANS was assessed by HR and HR variability parameters. Blood and saliva were collected at 5 min before (baseline) and 0, 5 10, 15, 20, 30, 40, 60, and 120 min after the examination to determine cortisol concentrations. The examination lasted for 5 min. Cardiac parameters included HR, the root mean square of successive differences between the consecutive interbeat intervals, the high frequency (HF) component of heart rate variability, and the ratio between the low frequency (LF) and HF parameter (LF/HF). Following the examination, peak plasma and saliva cortisol levels and the amplitude of the plasma and saliva cortisol response were higher in high responder cows than in low responders. Areas under the plasma and saliva cortisol response curves were greater in high responder cows. Plasma and salivary cortisol levels correlated significantly at baseline (r=0.91), right after examination (r=0.98), and at peak levels (r=0.96). Area under the HR response curve was higher in low responder cows; however, maximum HR and the amplitude of the HR response showed no differences between groups. Minimum values of both parameters calculated for the examination were higher in high responders. Following the examination, response parameters of root mean square of successive differences and HF did not differ between groups. The maximum and the amplitude of LF/HF response and area under the LF/HF response curve were lower in low responder cows, suggesting a lower sympathetic activation of the ANS. Although changes in behaviors indicated that the procedure was painful for the animals, no differences were observed either in vocalization or in attendant behavior between groups during the examination. Our results demonstrate that behaviorally more reactive animals exhibit increased plasma and salivary cortisol concentrations and higher cardiac autonomic responsiveness to transrectal examination than less reactive cows. Salivary cortisol may substitute for plasma cortisol when assessing response of cattle to stress.

Cattle temperament influences metabolism: metabolic response to glucose tolerance and insulin sensitivity tests in beef steers

Cattle temperament, defined as the reactivity of cattle to humans or novel environments, can greatly influence several physiological systems in the body, including immunity, stress, and most recently discovered, metabolism. Greater circulating concentrations of nonesterified fatty acids (NEFAs) found in temperamental cattle suggest that temperamental cattle are metabolically different than calm cattle. Further, elevated NEFA concentrations have been reported to influence insulin sensitivity. Therefore, the objective of this study was to determine whether cattle temperament would influence the metabolic response to a glucose tolerance test (GTT) and insulin sensitivity test (IST). Angus-cross steers (16 calm and 15 temperamental; 216 ± 6 kg BW) were selected based on temperament score measured at weaning. On day 1, steers were moved into indoor stanchions to allow measurement of individual ad libitum feed intake. On day 6, steers were fitted with indwelling rectal temperature probes and jugular catheters. At 9 AM on day 7, steers received the GTT (0.5-mL/kg BW of a 50% dextrose solution), and at 2 PM on day 7, steers received the IST (2.5 IU bovine insulin/kg BW). Blood samples were collected and serum isolated at -60, -45, -30, -15, 0, 10, 20, 30, 45, 60, 90, 120, and 150 min relative to each challenge. Serum was stored at -80°C until analyzed for cortisol, glucose, NEFA, and blood urea nitrogen concentrations. All variables changed over time (P < 0.01). For the duration of the study, temperamental steers maintained greater (P < 0.01) serum NEFA and less (P ≤ 0.01) serum blood urea nitrogen and insulin sensitivity (calculated using Revised Quantitative Insulin Sensitivity Check Index) compared with calm steers. During the GTT, temperamental steers had greater (P < 0.01) serum glucose, yet decreased (P = 0.03) serum insulin and (P < 0.01) serum insulin: serum glucose compared to calm cattle. During the IST, temperamental steers had greater (P < 0.01) serum insulin and a greater (P < 0.01) serum insulin: serum glucose as compared with calm steers. These data demonstrate that differences exist in the manner in which temperamental steers respond to glucose and insulin, potentially a result of elevated serum NEFA concentrations, which may result in changes in utilization and redistribution of energy in temperamental vs calm cattle.

Association of Temperament and Acute Stress Responsiveness with Productivity, Feed Efficiency, and Methane Emissions in Beef Cattle: An Observational Study

The aim of this study was to assess individual differences in temperament and stress response and quantify their impact on feed efficiency, performance, and methane (CH₄) emissions in beef cattle. Eighty-four steers (castrated males) (Charolais or Luing) were used. Temperament was assessed using two standardized tests: restlessness when restrained [crush score (CS)] and flight speed (FS) on release from restraint. Over a 56-day period individual animal dry matter intake (DMI) and weekly body weight was measured. Ultrasound fat depth was measured at the end of 56 days. Average daily gain (ADG), feed conversion ratio (FCR), and residual feed intake (RFI) were calculated. After the 56-day test period, animals were transported in groups of six/week to respiration chamber facilities. Blood samples were taken before and 0, 3, 6, and 9 h after transport. Plasma cortisol, creatine kinase (CK), glucose, and free fatty acids (FFA) were determined to assess physiological stress response. Subsequently, CH₄ emissions were measured over a 3-day period in individual respiration chambers. CS (1.7 ± 0.09) and FS (1.6 ± 0.60 m/s) were repeatable (0.63 and 0.51, respectively) and correlated (r = 0.36, P < 0.001). Plasma cortisol, CK, and FFA concentrations increased after transport (P = 0.038, P = 0.006, and P < 0.001, respectively). Temperament (CS) and CK concentration were correlated (r = 0.29; P = 0.015). The extreme group analysis reveals that excitable animals (FS; P = 0.032) and higher stress response (cortisol, P = 0.007; FFA, P = 0.007; and CK, P = 0.003) were associated with lower DMI. ADG was lower in more temperamental animals (CS, P = 0.097, and FS, P = 0.030). Fat depth was greater in steers showing calmer CS (P = 0.026) and lower plasma CK (P = 0.058). Temperament did not show any relationship with RFI or CH₄ emissions. However, steers with higher cortisol showed improved feed efficiency (lower FCR and RFI) (P < 0.05) and greater CH₄ emissions (P = 0.017). In conclusion, agitated temperament and higher stress responsiveness is detrimental to productivity. A greater stress response is associated with a reduction in feed intake that may both increase the efficiency of consumed feed and the ratio of CH₄ emissions/unit of feed. Therefore, temperament and stress response should be considered when designing strategies to improve efficiency and mitigate CH₄ emissions in beef cattle.

Physiological and metabolic responses of gestating Brahman cows to repeated transportation

This study characterized physiological responses to repeated transportation (TRANS) of gestating cows of differing temperaments. Cows were classified as Calm (C; = 10), Intermediate (I; = 28), or Temperamental (T; = 10). Based on artificial insemination date and pregnancy confirmation, cows were TRANS for 2 h on d 60 (TRANS1), 80 (TRANS2), 100 (TRANS3), 120 (TRANS4), and 140 (TRANS5) ± 5 d of gestation. Indwelling vaginal temperature (VT) monitoring devices were inserted 24 h before each TRANS with VT recorded from 2 h before TRANS and averaged into 5-min intervals through 30 min after TRANS. Serum samples were collected before loading and on unloading from the trailer to determine concentrations of cortisol, glucose, and nonesterified fatty acids (NEFA). Data were analyzed by repeated measures analysis in SAS. Serum cortisol concentrations were affected by temperament ( < 0.001), with T cows having the greater concentrations of cortisol before each TRANS event. All cows (100%) regardless of temperament exhibited elevations in cortisol following each TRANS event. Peak VT was greater ( < 0.001) at TRANS1 relative to all other TRANS events regardless of cow temperament. During TRANS, the T cows tended ( < 0.09) to have greater peak VT (39.86 ± 0.15°C) compared to C (39.41 ± 0.16°C) and I cows (39.55 ± 0.08°C). Area under the VT curve decreased ( = 0.002) from TRANS1 through TRANS5. Pre-TRANS serum glucose concentration at TRANS1 was greater ( < 0.03) for T (68.13 ± 4.31mg/dL) compared to I (53.42 ± 2.78 mg/dL) and C cows (52.76 ± 4.60 mg/dL). The C and I cows had greater changes in NEFA concentration between pre- and post-transport, and T cows showed the least change ( < 0.001). Cow VT and serum glucose concentration decreased in all temperaments ( < 0.01) with repeated TRANS; however, serum NEFA concentration post-TRANS did not vary ( > 0.10) with repeated TRANS events. Serum glucose concentrations were affected ( < 0.02) by a TRANS event by temperament interaction with T cows taking more TRANS events to decrease their change in glucose concentration compared to C and I cows. These results demonstrate that temperament influences physiological responses to stress in gestating Brahman cows. Although repeated transport in our study is confounded with day of gestation, seasonal changes, and learning from repeated handling and transport, repeated transport is a useful model of repeated stress in studying the effects of temperament.

Effect of grain type and processing index on growth performance, carcass quality, feeding behavior, and stress response of feedlot steers

One hundred sixty crossbred steers (538 ± 36 kg BW) were used in an 84-d experiment with a randomized block design to study the effects of wheat or barley grain processed to 2 different indices on growth performance, feeding behavior, carcass characteristics, stress, and temperament of finishing beef cattle. Treatments were a wheat-based diet (88.4% of diet DM; WH) and a barley-based diet (89% of diet DM; BA), processed to an index of either 75% (HI) or 85% (LO) of their original volume weight. Cattle were allocated to 16 feedlot pens (10 animals per pen, 4 pens per treatment), 8 of which were equipped with the GrowSafe system for monitoring feeding behavior. Flight speed, hair, and saliva samples were collected on d 1, 28, 56, and 84 to determine temperament, acute, and chronic stress. All steers were slaughtered at the end of the experiment, and carcass quality was evaluated. Cattle fed WH had a lower (P < 0.05) meal length and frequency of visits per meal and tended (P = 0.10) to have a lower DMI, meal size, and feeding time than those fed BA. The LO processing index increased (P = 0.05) DMI and reduced (P < 0.05) the G:F and the percentage of saleable meat of the carcass compared to HI. There was a trend (P = 0.09) for a grain × processing index interaction, where cattle fed BA-LO had a lower incidence of severe liver abscesses compared with cattle fed other treatments. Cattle fed WH had greater hair cortisol concentrations (P = 0.01) and flight speed (P < 0.01) than those fed BA. There was a trend (P = 0.07) for a grain × processing index interaction, where heifers fed WH-LO had a lower salivary cortisol than those fed other treatments. Results suggest that a LO processing index had a negative effect on feed efficiency and carcass performance and that the WH diet caused a range of effects on feed intake and behavior indicative of steers with greater excitability and chronic stress.