Hair cortisol concentration in pre‐ and postpartum dairy cows,and its association with body condition,hock health,and reproductive status

The objective of this study was to investigate the profiles of hair cortisol concentrations as an index of chronic stress in dairy cows in association with their health, nutrition, and reproductive parameters. For 25 Holstein dairy cows, hair was collected from the tail switch ?19.2 ± 11.4, 44.8 ± 11.9, 103.0 ± 9.9, and 168.0 ± 9.7 days postpartum (L0, L1, L2, and L3, respectively). Body condition scores were negatively correlated with hair cortisol concentrations (r = ?0.255), and hock health scores were positively correlated with hair cortisol concentrations (r = 0.236, p < 0.05). Hair cortisol concentrations during the postpartum period showed different patterns according to the time of first artificial insemination (AI) and fertility. Cows that were submitted to first AI by 86 days postpartum showed a peak hair cortisol concentration at L1, whereas cows with delayed first AI had a peak at L2. The hair cortisol concentrations of subfertile (≥168 days) cows were significantly higher at L1 and L2 compared with L0, whereas hair cortisol concentrations of fertile cows (<168 days) were not different among the sampling times. These results indicate that cows with health problems appear to experience greater chronic stress, which may impair their reproductive function.     

Adrenal cortex reactivity in dairy cows differs between lactational stages and between different feeding levels

Changes in ACTH challenge test characteristics in dairy cows changing their physiological status at different lactational stages and different feeding levels were not investigated in terms of repeatability yet. In 23 multiparous Holstein cows (10 cows fed a sole fresh herbage diet without concentrate, 13 cows fed with concentrate), three ACTH challenge tests were performed: once during pregnancy shortly prior to drying off ( T1 ), and in week 3 ( T2 ) and 8 ( T3 ) after parturition. Test characteristics were correlated to performance and metabolic parameters: DMI, BW, energy balance (EB), plasma concentrations of free fatty acids (NEFA) and beta‐hydroxybutyrate (BHB). Basal plasma cortisol concentrations were higher at T1 compared with T2 and T3 (p < .05). The adrenal cortex sensitivity (expressed as total AUC (AUC_t) of cortisol response after ACTH application) was lowest at T2 compared with T1 and T3 (p < .05). Ranking of the individual animals’ responses was not repeatable between time points of the ACTH tests. Enhancing the energy deficiency during early lactation by omission of concentrate did not affect baseline cortisol concentrations in plasma, but decreased peak height at T2 (p < .05). Baseline plasma cortisol concentrations were positively correlated with cortisol peak values after ACTH application, previous lactation performance, milk yield and BW (p < .05). The AUC_t was positively correlated with baseline cortisol concentrations, EB and DMI. Cortisol release after ACTH injection was lower in animals with high plasma concentrations of NEFA, BHB and with higher contents of fat and free fatty acids in milk (p < .05). Cortisol peak height after ACTH administration was higher in cows with a more positive EB, higher DMI and lower plasma concentrations of NEFA and BHB. In summary, cortisol responses to ACTH challenges in this study were not repeatable in dairy cows changing their physiological status.     

Competitive interactions among multiple non‐native salmonids and two populations of Atlantic salmon

Competitive interactions with non‐native species can have negative impacts on the conservation of native species, resulting in chronic stress and reduced survival. Here, juvenile Atlantic salmon (Salmo salar) from two allopatric populations (Sebago and LaHave) that are being used for reintroduction into Lake Ontario were placed into semi‐natural stream tanks with four non‐native salmonid competitors that are established in Ontario streams: brown trout (S. trutta), rainbow trout (Oncorhynchus mykiss), Chinook salmon (O. tshawytscha) and coho salmon (O. kisutch). Brown trout and rainbow trout reduced the survival and fitness‐related traits of Atlantic salmon, whereas Chinook salmon and coho salmon had no impact on these traits. These data support theories on ecological niche overlap and link differences in observed aggression levels with competitive outcomes. Measurements of circulating hormones indicated that the Atlantic salmon were not chronically stressed nor had a change in social status at the 10‐month time point in the semi‐natural stream tanks. Additionally, the Sebago population was better able to coexist with the non‐native salmonids than the LaHave population. Certain populations of Atlantic salmon may thus be more suitable for some environments of the juvenile stream phase for the reintroduction into Lake Ontario.     

二氢吡啶对雏鸡免疫功能的影响

将 2 3日龄海赛克斯父母代母雏 3 3 0只随机分为 6组 ,分别饲喂含二氢吡啶 0、2 5、50、1 0 0、1 50、2 0 0mg/kg的日粮 ,试验期 65d。用微量法测定血清新城疫抗体水平 ,放射免疫法测定血清 T3、T4、皮质醇的质量浓度 ,并作血液涂片 ,检测 T淋巴细胞百分比。结果表明 ,二氢吡啶可提高机体的免疫功能 ,且以 1 50 mg/kg组效果最显著 ,其血清抗体水平显著升高 ( P<0 .0 1 ) ,T淋巴细胞百分比呈上升趋势。血清 T3的质量浓度于试验后 60 d极显著高于对照组 ( P<0 .0 1 ) ,皮质醇质量浓度显著低于对照组 ( P<0 .0 5)。结果提示 ,二氢吡啶对免疫功能的促进作用与血清 T3质量浓度的显著升高和皮质醇质量浓度的显著降低有关     

Research Progress on Hair Cortisol as Evaluation Indicators of Chronic Stress

Making hair cortisol as the gold standard of reflecting chronic stress level is prospective and innovative.Hair cortisol not only can be used in detecting and estimating the chronic stress level of animals, but also can be benefit for understanding the body's physiological and pathological process and making effective health management strategy in time.Blood, saliva, urine and milk cortisol concentrations can be regarded as matrices for reflecting acute stress level as well, they have been used in detecting and establishing the diurnal profile of circulating cortisol studying.But hair which is a good supplementary matric can reflect the chronic stress level retrospectively.Hair cortisol as a reflection of the biochemical markers of chronic stress has the advantages of no invasive, relatively sensitive detection and convenient sampling stress, and hair cortisol is a heritable trait (h²=0.31).The utility of hair cortisol as a maker for HPA activity, and a useful tool for identifying genetic variation influences on long term individual differences in HPA activity.This article summarized the relationship between the cortisol and animal's healthy, the regulating mechanism and genetic adaptation change under chronic stress and the research progress of evaluation indicators during chronic stress, the research progress of hair as a matric of cortisol, the limitations and challenge of regarding hair cortisol as the biochemical marker to reflect the chronic stress level in the future.     

Effect of Long-distance Road Transport on Thyroid and Adrenal Function and Haematocrit Values in Limousin Cattle: Influence of Body Weight Decrease

The purpose of this study was to evaluate the effect of long-distance road transport as a relevant stressor on total and free iodothyronines, cortisol levels and haematocrit values in 10 male Limousin cattle. Serum T₃,T₄,fT₃,fT₄ and cortisol concentrations were analysed by immunoenzymatic assays. Serum cortisol levels and haematocrit modifications were also evaluated on the basis of percentage body weight decrease. The results showed a general increase of total and free iodothyronines and cortisol levels after short-and long-distance road transport and a decrease 15 days after transport, as compared to basal values. Significant positive correlations between T₃ and T₄, between T₃ and fT₃, and between T₄ and fT₄ were found. These results suggest that transport stress induces an increase in the activity of thyroid and adrenal function in Limousin cattle that is evident after even a short-distance road transport and continues to increase after long-distance transport.     

Measurement of Cortisol Metabolites in Faeces of Ruminants

Twenty-one metabolites were detected in faecal samples collected after infusion of (¹⁴C)cortisol into the jugular vein of sheep, using high-performance liquid chromatography/radiometric analysis plus mass spectrometry. One group of metabolites had molecular weights of between 302 and 308, and another group of 350, which indicates that the substances have a C₁₉O₃ or a C₂₁O₄ structure. Therefore, an enzyme immunoassay against 5-androstane-3-o1-11,17-dione-17-CMO:BSA was established. Faecal samples were collected from 10 cows immediately after transport and then during a course in which non-invasive diagnostic procedures were being taught (course 1). For comparison, faeces were sampled from another 5 cows that were being used for teaching invasive procedures (course 2). Six cows from a university farm served as controls. In the animals used in course 1, the highest concentrations of cortisol metabolites were measured immediately after transport to the university (median value: 2.2 mol/kg faeces). During the first 5 days at the university, the concentrations decreased to 0.52 mol/kg (median) and remained at this level during the rest of the course. The median concentration in the samples that were taken during course 2 (collected about 2 months after transport) was 0.48 mol/kg. There was no significant difference in the excretion of cortisol metabolites between these cows and the controls. We conclude from these data that, using the enzyme immunoassay against 5-androstane-3-o1-11,17-dione-17-CMO, we were able to detect transport/novel environment stress but not the potential disturbance that cows experience during diagnostic procedures.     

Acute cortisol responses of calves to four methods of dehorning by amputation

Objective To measure the plasma cortisol response in calves dehorned by four different methods (scoop, guillotine shears, saw, embryotomy wire) for 9 h after dehorning.
Design A physiological study with controls.
Procedure Horn amputation was carried out on calves restrained manually in a race.
Results The four methods of dehorning provoked similarly increased cortisol responses which lasted for 6 h. During the first hour after dehorning the plasma cortisol concentrations were similar to those following ACTH injection. The overall cortisol response to control handling was about 30% of the responses to dehorning.
Conclusions The similarity of the cortisol responses produced by the four methods of dehorning suggests that the distress experienced by calves following dehorning by amputation is similar regardless of method used.