The benzodiazepine brotizolam reduces fear in calves exposed to a novel object test.

The present study examined the effects of the intravenous administration of the anxiolytic drug brotizolam on the behavioral and physiological responsiveness of calves to novelty in a dose response fashion. Holstein Friesian heifer calves (39-41 weeks of age; body weight 200-300 kg) received an intravenous injection of either a vehicle control (12 calves) or one of four doses of brotizolam (8 calves per dose): 0.0125, 0.05, 0.2 and 0.8 mg/100 kg body weight. They were then individually subjected to a 'combined' test involving exposure to a novel environment (open field, OF) for 5 min followed by the sudden introduction of a novel object (NO) that remained in place for a further 10 min. Behavioral, heart rate and plasma cortisol responses were recorded in all animals. Compared to vehicle treatment, the highest dose of brotizolam dose-dependently and significantly increased the time spent in locomotion and the distance travelled near the NO, as well as the time spent in contact with the NO. In addition, post-test plasma cortisol concentrations changed in a dose-dependent manner over time: they decreased between 0 and 10 min after the test in calves that had received the two highest doses of brotizolam, whereas they increased in vehicle-treated and low-dosage calves. There were no effects of brotizolam on vocalization or locomotion during the OF phase of the test or on vocalization following introduction of the NO. These findings strongly support the notion that interaction with a novel object in a novel arena represents a behavioral index of fear and fearfulness in calves, and that vocalization and locomotion in an OF reflect other independent characteristics.

Social rank of pregnant sows affects their body weight gain and behavior and performance of the offspring.

Previous studies on group housing of pregnant sows have mainly focused on reproduction, but we hypothesized that the social rank of pregnant sows housed in groups could also affect birth weight, growth, and behavior of their offspring. Therefore, in the present study, pregnant gilts and sows were housed in 15 different groups (n = 7 to 14 animals per group) from 4 d after AI until 1 wk before the expected farrowing date. All groups were fed by an electronically controlled sow feeding system that registered, on a 24-h basis, the time of first visit, number of feeding and non-feeding visits, and number of times succeeding another sow within 2 s. Only in the first 6 groups (n = 57 animals), agonistic interactions were observed continuously. The percentage of agonistic interactions won was highly correlated (r(s) = 0.90, P < 0.001) with the percentage of displacement success (DS) at the feeding station, which was calculated as: [the number of times succeeding another sow within 2 s/(the number of times succeeded by another sow within 2 s + the number of times succeeding another sow within 2 s)] x 100. This allowed us to classify all sows (n = 166) according to their DS: high-social ranking (HSR) sows had a DS >50% (n = 62) and low-social ranking (LSR) sows a DS <50% (n = 104). Body weights before AI did not differ between HSR and LSR sows, but HSR sows gained more BW during gestation, and lost more BW and back-fat during lactation (P < 0.001). Maternal salivary cortisol concentrations at 2, 7, and 13 wk after AI did not differ between HSR and LSR sows, nor did gestation length, litter size, or percentage of live born piglets. During a novel object (NO) test at 3 wk of age, HSR offspring moved and vocalized more than LSR offspring (P < 0.05). In addition, the latency time to touch the NO was shorter in HSR offspring (P < 0.05), and HSR males spent more time near the NO than LSR males (P < 0.01). At weaning, HSR offspring weighed more than LSR offspring (P < 0.05), and at slaughter HSR offspring had more lean meat than LSR offspring (P < 0.05). Results indicate that the social rank of the sow during gestation affects her own BW gain and loss as well as the growth and behavior of her offspring. Pig breeders that apply group housing for pregnant sows should pay attention to reducing competition around the feeding area, which may reduce aggression among the sows and minimize differences between HSR and LSR sows.

Effects of milk production capacity and metabolic status on HPA function in early postpartum dairy cows.

Increasing milk yields in modern dairy cows cause concern that high yield may impair the cows' health and welfare, for example, via negative effects on metabolic status and hypothalamo-pituitary-adrenocortical (HPA) function. This study aims to investigate whether a high level of milk production, and the associated metabolic status, affects HPA function in dairy cows and changes their adaptive capacity. Additionally, it aims to establish whether possible effects of milk production level only show under challenging conditions. Holstein-Friesian cows, which produced on average 11,443 and 7727 kg of fat and protein-corrected milk (FPCM)/305 d in their previous lactation, were compared. During the dry period, the cows were fed to requirements or overfed. High milk yield and the concomitant large energy deficit were associated with 1) increased pituitary (re)activity, i.e., increased ACTH baseline concentrations and higher ACTH concentrations after corticotropin-releasing hormone (CRH) administration, and 2) decreased adrenocortical reactivity, i.e., lower cortisol responses after ACTH administration. Although significant, the effects of milk production level on HPA function were relatively small. Animals showed seemingly normal hormonal responses to CRH and ACTH administration. Also, cortisol baseline concentrations were unaffected. It seems, therefore, unlikely that the adaptive capacity of the high-producing cows was significantly impaired compared with their low-producing herdmates.

Individual differences in behavioral and physiological responsiveness of primiparous dairy cows to machine milking.

An experiment was performed in primiparous dairy cows (n = 23) to examine consistency of individual differences in reactivity to milking, and correlations between measures of behavior, physiology, and milk ejection. Responsiveness to milking was monitored during the first machine milking, on d 2 of lactation, and during milkings on d 4 and 130 of lactation. Measurements included kicking and stepping behavior, plasma cortisol and plasma oxytocin, heart rate, milk yield, milking time, milk flow rate, and residual milk obtained after administration of exogenous oxytocin. With repeated early lactation milkings, residual milk and the incidence of abnormal milk flow curves decreased. On d 130 of lactation all heifers exhibited normal milk ejection. Except for higher plasma cortisol concentrations on d 2, all measures were consistent over time between d 2 and 4 of lactation as indicated by significant rank correlations. Individual differences in the behavioral response to udder preparation were consistent over time between early lactation milkings and d 130 of lactation. Residual milk, milk yield, maximum milk flow rate, plasma oxytocin and heart rate during udder preparation were similarly interrelated on d 2 and 4 of lactation. High heart rate responses on d 2 and 4 were associated with enhanced inhibition of milk ejection. In contrast, behavior recorded during the milking process was unrelated to ease of milk removal. Our results indicate that milking at the beginning of lactation may be stressful to some heifers, to the extent that milk ejection is inhibited, but less disturbing to others. The existence of consistent behavioral and physiological responses in the present study suggests that responsiveness of dairy heifers to milking is mediated by stable animal characteristics.

Stress responses during milking; comparing conventional and automatic milking in primiparous dairy cows.

A comparative study was performed to evaluate the differences in behavioral and physiological stress responses during milking between cows that were milked by an automated milking system (AM-cows) and cows that were milked in a conventional tandem parlor (TM-cows). In a randomized design, 36 primiparous Holstein-Friesian dairy cows were observed and blood sampled (1-min intervals) individually during milking. AM-cows spent less time standing with their heads outside the feeding trough than TM-cows and had a lower heart rate. In addition, AM-cows had lower maximum plasma adrenaline and noradrenaline concentrations during milking. No differences were found in the number of steps. After tactile stimulation of the teats either by hand or by the cleaning brush, mean oxytocin concentrations did not differ. In AM-cows, however, elevated oxytocin levels were prolonged at the end of milking. Averaged over the first five blood samples, AM-cows tended to have higher plasma cortisol concentrations than TM-cows, but median fecal concentrations of the cortisol metabolite dioxoandrostane were comparable. Maximum quarter milk flow, maximum udder milk flow and residual milk as a percentage of the total milk volume was comparable. From this study it is concluded that behavioral and physiological responses, both in automatically and in conventionally milked cows, were relatively low and were typical for cows being milked. We therefore conclude that, as far as the welfare of the dairy cow during milking is concerned, automatic milking and conventional milking are equally acceptable.

Transgenesis may affect farm animal welfare: a case for systematic risk assessment.

This paper considers (potentially) harmful consequences of transgenesis for farm animal welfare and examines the strategy of studying health and welfare of transgenic farm animals. Evidence is discussed showing that treatments imposed in the context of farm animal transgenesis are by no means biologically neutral and may compromise animal health and welfare. Factors posing a risk for the welfare of transgenic farm animals include integration of a transgene within an endogenous gene with possible loss of host gene function (insertional mutations), inappropriate transgene expression and exposure of the host to biologically active transgene-derived proteins, and in vitro reproductive technologies employed in the process of generating transgenic farm animals that may result in an increased incidence of difficult parturition and fetal and neonatal losses and the development of unusually large or otherwise abnormal offspring (large offspring syndrome). Critical components of a scheme for evaluating welfare of transgenic farm animals are identified, related to specific characteristics of transgenic animals and to factors that may interact with the effects of transgenesis. The feasibility of an evaluation of welfare of transgenic farm animals in practice is addressed against the background of the objectives and conditions of three successive stages in a long-term transgenic program. Concrete steps with regard to breeding and testing of transgenic farm animals are presented, considering three technologies to generate transgenic founders: microinjection, electroporation and nuclear transfer, and gene targeting including gene knockout. The proposed steps allow for unbiased estimations of the essential treatment effects, including hemi- and homozygous transgene effects as well as effects of in vitro reproductive technologies. It is suggested that the implementation of appropriate breeding and testing procedures should be accompanied by the use of a comprehensive welfare protocol, specifying which parameters to monitor, at which stages of the life of a farm animal, and in how many animals. Some prerequisites and ideas for such a protocol are given. It is anticipated that systematic research into the welfare of farm animals involved in transgenesis will facilitate the use of the safest experimental protocols as well as the selection and propagation of the healthiest animals and, thereby, enable technological progress that could be ethically justified.

Farm animal welfare research in interaction with society.

Over the last 30 years concern about farm animal welfare has increased and has become a public issue in the Netherlands. Public discussion has stimulated research in this field, financed by both government and industry. Dutch society in general and consumers of animal products in particular, want to see high standards of welfare for production animals. Good animal welfare has gradually gained more impact in the total quality concept of the product. This will encourage scientists to continue to analyse the welfare status of animals and to come up with innovative solutions for the remaining problems. At ID-Lelystad much effort is put into farm animal welfare research. This research includes for example, the development of behavioural tests for quantifying and interpreting fear in cattle, investigations into the effects of dietary iron supply and a lack of roughage on behaviour, immunology, stress physiology, and pathology in veal calves, studies of the ontogeny of tail biting in finishing pigs and feather pecking in laying hens as well as evaluation of the welfare effects of automatic milking in dairy cows. The results of these projects contribute to concrete improvements in animal husbandry and expertise and support policy making and legislation. The animal industry as well as retailers should aim at the further implementation of this knowledge and to specify welfare standards to guarantee consumer acceptance of animal production.

Short communication: effects of isolation stress on mammary tight junctions in lactating dairy cows.

Eighteen cows had been selected for their responsiveness to psychological stress during the first lactation and were classified as having low (n = 10) or high (n = 8) cortisol concentrations in response to isolation-induced stress. In the present study these cows, now in their second lactation, were used to determine the effect of social isolation stress on the permeability of mammary tight junctions. During the experiment, each cow was isolated from the rest of the herd for 55 h. After the 1st h of isolation, each cow received a bolus infusion of endotoxin in one hind quarter in order to challenge tight junctions. Blood samples were taken throughout to measure lactose, which was used as an indicator of tight-junction leakiness. After 1 h of isolation, stress caused an increase in tight junction permeability in both groups, which was further enhanced by the endotoxin treatment. Although the permeability did not differ significantly between the two groups, it was consistently higher in the high-cortisol group, which was also the most stress-responsive group. Thus, psychological stress may adversely affect milk quality by allowing serum components to leak into milk.

Coping styles in animals: current status in behavior and stress-physiology.

This paper summarizes the current views on coping styles as a useful concept in understanding individual adaptive capacity and vulnerability to stress-related disease. Studies in feral populations indicate the existence of a proactive and a reactive coping style. These coping styles seem to play a role in the population ecology of the species. Despite domestication, genetic selection and inbreeding, the same coping styles can, to some extent, also be observed in laboratory and farm animals. Coping styles are characterized by consistent behavioral and neuroendocrine characteristics, some of which seem to be causally linked to each other. Evidence is accumulating that the two coping styles might explain a differential vulnerability to stress mediated disease due to the differential adaptive value of the two coping styles and the accompanying neuroendocrine differentiation.

Effects of repeated jugular puncture on plasma cortisol concentrations in loose-housed dairy cows.

In three experiments, the effects of venipuncture on plasma cortisol concentrations were studied in loose-housed dairy cows. In Exp. 1, two blood samples were collected 18 min apart on three alternate days from 20 dairy cows for studying their adrenocortical response to a single venipuncture. To further evaluate the effect of cows anticipating venipuncture, in Exp. 2, 15 dairy cows were sequentially venipunctured once daily on 12 successive days in a randomized order in groups of five, starting 15 min apart. In Exp. 3, 10 primiparous cows were used on three alternate days to study habituation to serial sampling (i.e., collection of five blood samples by venipuncture, 15 min apart). In cows accustomed to handling, jugular puncture did not affect cortisol concentrations in plasma collected 18 min later. Average daily cortisol concentrations varied between 2.07 +/- .38 and 3.81 +/- .56 ng/mL in the first (t = 0) and between 1.43 +/- .15 and 2.61 +/- .72 ng/mL in the second (t = 18) blood samples. Likewise, when cows were sampled sequentially once a day, the order of sampling between and within groups did not influence (P > .05) plasma cortisol concentrations. In contrast, primiparous dairy cows that were less used to being handled showed an average increase in cortisol concentrations when five samples were collected by venipuncture 15 min apart. During successive sampling sessions, however, the cows did not decrease or increase plasma cortisol concentrations in response to repeated serial sampling at the group level (P > .05). Between individuals, the maximum effect of repeated venipuncture on cortisol concentrations (4.5 to 22.6 ng/mL), the time at which the effect reached its maximum (30 to 60 min), and the consistency of the response pattern over successive series varied largely. The results of this study show that in cows that were accustomed to handling and to being restrained, baseline cortisol concentrations can be measured in single blood samples that are collected by jugular puncture within 1 min after first approaching the cow. When successive blood samples need to be collected within 15 to 20 min, jugular puncture may induce an increase in cortisol concentration, which seems to depend on the handling experience of the animals and on individual differences.

Stress enhanced reduction in peripheral blood lymphocyte numbers in dairy cows during endotoxin-induced mastitis.

Two groups of Holstein dairy cows, which showed either high- (HC; n = 8) or low (LC; n = 10) plasma cortisol concentrations in response to a psychological stressor (novel-environment test) in their first lactation, were used 1 year later for studying the effects of psychological stress on various aspects of the host defence during endotoxin-induced mastitis. Social isolation was used as a stressor; endotoxin was used to activate the host defence. HC-cows appeared to be more stressed by the experimental procedure than LC-cows. One hour after having been isolated, rectal temperature increased (+0.59 degrees C) in HC- but not in LC-cows. Handling, related to the intra-mammary administration of endotoxin, induced a higher increase in cortisol concentration in HC- than in LC-cows 1 h after injection. In addition, HC-cows vocalised significantly more frequently (595 +/- 222) than LC-cows (81 +/- 24) between 1.5 and 9.5 h after isolation. Between 3 and 5.5 h after endotoxin-treatment, cortisol concentrations increased profoundly in both LC- and HC-cows and peaked at 24.6 +/- 3.8 and 22.8 +/- 3.1 ng ml(-1), respectively. The rise in plasma cortisol concentration was associated with a decrease in the number of circulating lymphocytes between 0 and 8 h post injection (PI). Between 8 and 10 h PI, the number of circulating lymphocytes in HC-cows further decreased (40%) to 1.58x10(6) cells ml(-1) and remained so until 21 h PI. This was not the case with the LC-cows. The results show that a differing sensitivity of dairy cows to environmental stressors is associated with a significant difference in the number of circulating leukocytes following intra-mammary administration of endotoxin during a period of social isolation. The results further suggest that, apart from adrenocortical hormones, other factors related to general stress-responsiveness modulate the number of peripheral lymphocytes in dairy cows during endotoxin-induced mastitis. During environmental stress, these factors may enhance endotoxin-induced reduction in circulating lymphocyte numbers, particularly in cows that are sensitive to environmental stressors. As to the clinical relevance of these differences in stress responsiveness, no differences between LC- and HC-cows were found in disease incidence nor in duration of a disease episode during both the 1st and 2nd lactation. In the 2nd lactation. HC-cows tended to produce less milk than LC-cows.