Repeated mixing and isolation: Measuring chronic, intermittent stress in Holstein calves

Abstract

Objectives of this study were to determine the physiological effects of psychological stress applied to dairy calves and to test if molasses consumption could be used to validate that a stressed condition was achieved. Twenty male calves (3 wk old) received jugular catheters and were randomly assigned to control (CTR; n = 4 pens of 1 calf per pen) or social stress treatments (STR; n = 4 pens of 4 calves per pen). The STR treatment included 5 cycles of 24-h isolation followed by regrouping with unfamiliar animals for 48 h (over 15 d). An ACTH challenge (0.1 IU/kg of body weight) was used to determine adrenal fatigue. Peak and total cortisol concentrations were greater for STR calves until the ACTH challenge. After the ACTH challenge, CTR calf cortisol increased and STR calf cortisol continued to decrease, suggesting adrenal fatigue. The number of calves that became positive for fecal shedding of Salmonella after the acute stress of being moved and the number of calves that were positive after the move decreased with each move. Fifty-six percent of STR calves changed from negative to positive for shedding after the first move compared with 18.75% of STR calves remaining negative after the third move. Difference in fecal shedding of Enterobacteriaceae from samples taken before and after moving calves on d 6 was less than that on d 2, 3, and 5. Leukocyte counts were not different, but trends for day effects were detected for neutrophil and monocyte percentages. Molasses consumption was greater for STR calves on d 2 and 11, as was total consumption. Latency to lie after eating also increased as the study progressed; STR calves required more time to lie after eating on d 12 than on d 3, and latency to lie was greater for STR than CTR on d 4, 8, 12, and 14. The STR calves also stood more than the CTR calves in the 4-h afternoon period on d 4, 5, 7, and 14. However, during the 4-h morning observations on d 14 (ACTH challenge), CTR calves stood more than STR calves. This model induced chronic stress, as characterized by adrenal fatigue, which was confirmed by molasses consumption and behavior changes. Therefore, molasses consumption could be used to confirm social stress in experimental models.

Dairy Cattle, a Potential Reservoir of Human Campylobacteriosis: Epidemiological and Molecular Characterization of Campylobacter jejuni From Cattle Farms

“…Social stresses such as social isolation, instability, and crowding can change pathogen exposure and transmission dynamics among individuals (Proudfoot and Habing, 2015). They can also lead to changes in the immunity of individuals and increase pathogen shedding (Aich et al, 2007; Wilcox et al, 2013).…”

Responses of dairy cows with divergent residual feed intake as calves to metabolic challenges during midlactation and the nonlactating period

“…Repeated exposure to acute stressors will inevitably prompt repeated cortisol responses and production losses may occur in response to the associated increase in energy consumption to mount this response. Conversely, repeated exposure to stressors, resulting in chronic stress, may also lead to adrenal fatigue or habituation and result in reduced responsiveness to ACTH (Wilcox et al, 2013). Further experiments are required to confirm that low-RFI dairy cattle are less adrenally responsive compared with high-RFI dairy cattle and to directly measure energy expenditure in response to HPA axis activation.…”

ADSA Foundation Scholar Award: New frontiers in calf and heifer nutrition—From conception to puberty

“…The preweaning and weaning periods have been the most studied (Figure 1) but remain among the most challenging stages of a calf's life, as reflected by high morbidity and mortality rates (USDA, 2016; Urie et al, 2018b). Calves are highly susceptible to disease during this period due to a combination of factors, including failed passive transfer of immunity (Shivley et al, 2018;Renaud et al, 2020), social stress, and environmental and housing conditions (Wilcox et al, 2013;Roland van Niekerk et al: ADSA FOUNDATION SCHOLAR AWARD Figure 1. Several key windows of developmental programming (embryo, fetus, neonatal, preweaning, weaning, pre-and postpubertal) exist throughout the first years of a heifer's life.…”