Novel breeding box has variable effects on heart rate and cortisol response of cattle

Cattle stress and pregnancy responses when imposing different restraint methods for conducting fixed time artificial insemination

Physiological stress responses have been associated with lesser pregnancy rates in beef cattle. Alternative cattle restraint methods have been developed to reduce this negative effect. The objective was to determine if there was a difference in pregnancy rate as a result of fixed-time artificial insemination (FTAI) in Bos taurus females when using a breeding box compared with a squeeze chute for restraining cows when conducting FTAI. There were FTAI treatment regimens imposed on cows and heifers at two separate locations (Virginia Tech University, VT; and R.A. Brown Ranch, RAB) with the FTAI being conducted while animals were restrained in a squeeze chute (n = 169) or a breeding box (n = 162). There was imposing of a 7-day Co-Sync + CIDR pre-breeding treatment regimen. Females were randomly assigned to treatments just prior to breeding. Immediately following breeding, blood was collected using coccygeal venipuncture procedures for assessment of plasma cortisol concentration. Chute and exit scores (1-5) were determined at the time of FTAI. Pregnancy rate, cortisol, chute score, and exit score were analyzed. There was no difference in pregnancy rate between treatments (57 ± 26% and 69 ± 26 %, respectively P = 0.59).There were differences in chute (1.52 ± 0.05 and 1.27 ± 0.05, respectively P < 0.05) and exit (1.26 ± 0.04 and 1.08 ± 0.04, respectively P < 0.05) scores between the two treatment groups. Results from the present study are not conclusive in ascertaining effects of the two types of restraint during FTAI on reproductive efficiency.

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.

Board invited review: The importance of the gestation period for welfare of calves: maternal stressors and difficult births

The prenatal period is of critical importance in defining how individuals respond to their environment throughout life. Stress experienced by pregnant females has been shown to have detrimental effects on offspring biology in humans and a variety of other species. It also is becoming increasingly apparent that prenatal events can have important consequences for the behavior, health, and productivity of offspring in farmed species. Pregnant cattle may experience many potentially important stressors, for instance, relating to their social environment, housing system and physical environment, interactions with humans and husbandry procedures, and their state of health. We examined the available literature to provide a review of the implications of prenatal stress for offspring welfare in cattle. The long-term effects of dystocia on cattle offspring also are reviewed. To ensure a transparent and repeatable selection process, a systematic review approach was adopted. The research literature clearly demonstrates that prenatal stress and difficult births in beef and dairy cattle both have implications for offspring welfare and performance. Common husbandry practices, such as transport, were shown to influence offspring biology and the importance of environmental variables, including thermal stress and drought, also were highlighted. Maternal disease during pregnancy was shown to negatively impact offspring welfare. Moreover, dystocia-affected calves suffer increased mortality and morbidity, decreased transfer of passive immunity, and important physiological and behavioral changes. This review also identified considerable gaps in our knowledge and understanding of the effects of prenatal stress in cattle.

Estimation of Genetic Parameters for Perinatal Sucking Behavior of Italian Brown Swiss Calves

Brown Swiss breeders sometimes experience difficulties in feeding calves because of the weak sucking ability of the calves in the early days of life. For the welfare of the calves, they should be suckled by their dams or should aggressively ingest colostrum immediately after birth. The composition of colostrum changes rapidly during the first few days of lactation, and the ability of calves to absorb the Ig decreases quickly as well. The aim of this study was to increase our knowledge of environmental and genetic components affecting the sucking response, to evaluate the possibility of selecting for this trait. Sucking ability was recorded in 3 categories (drank from the milk bucket nipple or bottle without help, drank with help, did not drink) at 5 post-natal meals (6, 12, 24, 48, and 72 h from birth). Records were analyzed with 2 different models: a single-trait threshold sire model, in which all observations were analyzed as a single trait with 5 levels, and a multiple-trait threshold liability sire model, in which meal-by-meal observations were analyzed as 5 different binary traits. Management procedures, the interval between birth and meals, parity, and season of birth were environmental factors affecting the variability in sucking ability. The heritability estimate for the single-trait analysis was 0.14, whereas heritabilities for the multiple-trait analysis were 0.26, 0.22, 0.21 0.12, and 0.13 for the first, second, third, fourth, and fifth meal, respectively. Estimated genetic correlations among traits were high (0.82 to 0.99). This study suggests the possibility of selection based on sucking ability. Future collection of larger data sets on the sucking response of calves in the first 2 meals after birth would increase the accuracy of genetic parameter estimates.

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.

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.

A noninvasive radiotelemetry system to monitor heart rate for assessing stress responses of bovines

A noninvasive radiotelemetry system was developed to monitor heart rates of cows and to view and analyze data. The system was validated by comparing heart rate data of two restrained heifers collected simultaneously using telemetric and direct electrocardiogram measurements and by acquiring data over 72 h from two dry cows housed in an experimental handling facility consisting of a free-stall pen, a holding pen, a pass-through stall, and a second holding pen. Telemetric and direct measurements in response to pharmacological elevation of heart rates were essentially identical. For cows in the experimental facility, peristimulus-time histograms indexed to standing or lying showed that average heart rates for cows increased 4.0 +/- 1.4 beats/min after cows stood and decreased 4.8 +/- 1.0 beats/min after cows lay. Similarly, the average heart rate for the cow naive to the facility increased from 60 to 86 beats/min and remained elevated for 6.3 min when heart rate was indexed to maximal heart rate within +/- 3 min of entry into the pass-through stall. Heart rate for the naive cow increased consistently from around 60 to over 160 beats/min during repeated agonistic encounters between animals. Heart rate for the other cow was not affected by the encounters. These results show clearly that heart rate can be used to monitor animal anxiety.

Effects of prenatal stress on the fetal calf

Twelve pregnant Brahman cows were randomly assigned to one of two treatment groups: 1) transported in a stock trailer for 24.2 km, unloaded at a second farm and penned for 1 hr, and then returned to the original farm (TRANS, n = 6); or 2) walked through the handling facilities (SHAM, n = 6). Treatments were repeated at 60, 80, 100, 120, and 140 d of gestation. Calves were delivered by cesarean section on d 266 of gestation. The male:female ratio was 4:2 and 5:1 for the TRANS and SHAM treatment groups, respectively. Before calf removal and severance of the umbilical blood flow, a blood sample was collected from the calf to determine plasma concentrations of adrenocorticotropin (ACTH) and cortisol. The calf was then sedated and exsanguinated, after which pituitary and adrenal glands were collected. The adrenals were immediately weighed, and a cross-section from the left adrenal was stored in 4% paraformaldehyde until being embedded in paraffin. Eight sections from each adrenal were sliced (5 microns), fixed, and then stained with Harris' hematoxylin and eosin. Areas of the cortex and medulla were calculated with a computerized digitizing unit and tracing of the viewed section. The TRANS calves had heavier body weights (BW) (28.7 vs. 23.9 +/- 1.8 kg; P < 0.07), pituitary glands (12.63 vs. 8.24 +/- 1.10 g/kg BW; P < 0.008), and heart weights (5.58 vs. 5.17 +/- 0.58 g/kg BW; P < 0.05) than did the SHAM calves. Plasma concentrations of ACTH and cortisol did not differ between SHAM and TRANS calves (57 vs. 82 +/- 14 pg/ml and 7.0 vs. 6.7 +/- 0.9 ng/ml, respectively; P > 0.2). Adrenal gland weight and medulla-to-cortex ratio did not differ between SHAM and TRANS calves (0.61 and 0.73 +/- 0.03 g and 0.97 and 0.99 +/- 0.12 g, respectively; P > 0.2). These results suggest that the altered response to stress in prenatally stressed calves is not associated with morphological changes in the adrenal gland but may be due to effects of prenatal stress on the fetal pituitary.

Ruminal, cardiorespiratory and adrenocortical sequelae of Na2EDTA-induced hypocalcaemia in calves

A study was undertaken to provide further information on the ruminal, cardiorespiratory and hypothalamo-pituitary-adrenocortical (HPAC) physiological sequelae of hypocalcaemia in dairy calves. The functional picture observed in standing calves experiencing Na2EDTA-induced progressive hypocalcaemia showed a biphasic pattern. During the first phase (Ca2+ varying between 1.20 +/- 0.09 and 0.64 +/- 0.15 mmol/L, mean +/- SD), the animals became dull and lethargic, shifting their weight from one hind limb to the other, with cool extremities and hypersalivation. Their ventilation was slightly increased but their heart rate, thoracoabdominal pressure, pulmonary mechanics, haemoglobin and temperature remained constant. Conversely, their systemic arterial pressure (SAP) and the amplitude of their ruminal contractions (RCA) were severely decreased. During the second phase (Ca2+ < 0.64 +/- 0.15 mmol/L), there was restlessness, tachycardia, hypertension, polycythaemia and, finally, inability to stay upright. It is suggested that the diminished Ca2+ availability caused smooth-muscle and myocardial dysfunctions which could explain the RCA and SAP changes recorded during the first phase, whereas neural and/or humoral sympathetic discharge probably accounted for the reversal in SAP and heart rate when Ca2+ was decreased further. Serum cortisol increased regularly and remained significantly correlated with Ca2+ in each animal. Moreover, regression of delta cortisol/delta Ca2+ on delta Ca2+/delta Na2EDTA was significant (p < or = 0.001). It was concluded that mild asymptomatic hypocalcaemia severely impairs ruminal function, which will progressively worsen the Ca2+ deficit; that the inability to maintain posture in hypocalcaemia is not due to hypotension; and that the higher the HPAC response to hypocalcaemia, the higher the resistance to its effects. An asymptomatic periparturient cow with barely detectable ruminal activity may merit preventive calcium borogluconate therapy. Also, the physiological role of hypotension in explaining the clinical picture may be less important than other processes, such as neuromuscular failure. Finally, the present results imply a possible HPAC exhaustion in cows with periparturient paretic hypocalcaemia.