Coat color affects cortisol and serotonin levels in the serum and hairs of Holstein dairy cows exposed to cold winter

Hypothalamic Neuromodulation of Hypothermia in Domestic Animals

When an organism detects decreases in their core body temperature, the hypothalamus, the main thermoregulatory center, triggers compensatory responses. These responses include vasomotor changes to prevent heat loss and physiological mechanisms (e.g., shivering and non-shivering thermogenesis) for heat production. Both types of changes require the participation of peripheral thermoreceptors, afferent signaling to the spinal cord and hypothalamus, and efferent pathways to motor and/or sympathetic neurons. The present review aims to analyze the scientific evidence of the hypothalamic control of hypothermia and the central and peripheral changes that are triggered in domestic animals.

Physiological Stress Responses in Cattle Used in the Spanish Rodeo

Certain events can cause distress in cattle. In Spain, there is a sport similar to rodeo called persecution and takedown, in which calves are harassed and knocked down by riders. In this study, the physiological stress response of calves (n = 260) is assessed by measuring hormonal physiological parameters. Salivary samples were collected from Salers (n = 110) and Lidia (n = 150) calves before, during, and after the persecution and takedown event. The hormones epinephrine, cortisol, serotonin, and dopamine were determined in saliva samples using enzyme-immunoassay techniques. The results obtained revealed that epinephrine and cortisol levels increased during the event in Salers calves, with a significant increase (p < 0.05) in the case of epinephrine, although after the event, these values returned to their initial state. Therefore, this sport supposes an assumable punctual stressor stimulus for the animal. In contrast, in Lidia calves, cortisol and epinephrine levels decreased, with a significant decrease (p < 0.05) in the case of cortisol, which may be related to the temperament of this breed and facing a stressful situation in a different manner. This is confirmed by serotonin and dopamine levels that were altered in Lidia calves with respect to the other group studied. In conclusion, the sport of persecution and takedown produces a physiological response of adaptive stress assumable for the animals.

Coat color affects the resilience against heat stress impacts on testicular hemodynamics, reproductive hormones, and semen quality in Baladi goats

Drastic climatic changes threaten animal productivity and prolificacy, whose adaptability is governed by its pheno- and genotypic traits. This study was aimed at investigating the effect of coat color on the adaptability of goat bucks under heat stress conditions from the perspectives of testicular blood flow (TBF) and biometry, reproductive hormones, and semen quality. Twenty bucks (Capra hircus) bearing different coat colors were selected from a large flock and divided into four equal groups (n = 5 each) as follows: black coat (BC; 100% black), brown coat (BrC; 100% dark brown), white coat (WC; 100% white), white-black coat (WBC; 50-60% white). Bucks were examined for TBF [Doppler ultrasonography and serum nitric oxide (NO)], testosterone (T) and luteinizing hormone (LH), seminal plasma oxidative biomarkers [catalase (CAT), total antioxidant capacity (TAC), and malondialdehyde (MDA)], and sperm traits percentages [progressive motility (PM), viability (SV), normal morphology (NM), and sperm concentration (SC) once a week for seven consecutive weeks (W1-W7) in the summer season (temperature humidity index = 88.4-92.2). Specifically, at W3-W7, darker bucks (BC and BrC) testicular volume, testicular colored area, T, NO, CAT, TAC, PM, SV, NM, and SC (W7 only) differed significantly (P < 0.05) by decrease than the lighter ones (WC and WBC). Both Doppler indices and serum MDA concentrations were elevated (P < 0.05) at W3-W7 in the BC and BrC bucks compared to WC and WBC groups. In conclusion, bucks with lighter coats were more resistant to the negative effects of HS on TBF, seminal oxidative biomarkers, and semen quality.

Stress Concepts and Applications in Various Matrices with a Focus on Hair Cortisol and Analytical Methods

When studying stress in animals, it is important to understand the types of stress and their classification, and how to assess the stress levels in different animal species using different matrices accurately and precisely. The classification of stress types helps to distinguish between good stress (eustress) and bad stress (distress). Hence, first, it is crucial to assess the animal's level of stress in a non-intrusive manner and second to identify the type of stress that is best suited to its environment. Third, it is also important to analyze the obtained samples using a suitable method to increase the validity of stress hormone measurements. Therefore, in this review, we aim to: (1) explain the classification of stress, (2) discuss the wide range of body matrices (e.g., saliva, milk, hair, urine, feces, sweat, fins, etc.) that can be used as samples to evaluate stress levels, as well as their comparisons and limitations, and present the reliable matrices for measuring stress hormones with special emphasis on hair, (3) compare the analytical methods for measuring stress hormones after sample preparation. Despite some literature that does not include hair as a reliable matrix for evaluating stress levels, hair is one of the matrices for measuring long-term stress hormone accumulations. This review discusses some factors that influence the level of stress hormones in the hair. By understanding these issues, the scientific community will not only be able to improve the understanding of stress and biomarker evaluation but also suggest how to deal with the consequences of stress in future research.