Effect of castration method on neurohormonal and electroencephalographic stress indicators in Holstein calves of different ages

Abstract

As public concern for food animal welfare increases, a need to validate objective pain assessment tools exists in order to formulate animal welfare policies and facilitate regulatory approval of compounds to alleviate pain in livestock in the United States. The aims of this study were (1) to compare the physiological response to pain induced by surgical and nonsurgical (band) castration in calves and (2) to elucidate age-related differences in pain response of calves subjected to different castration methods. Seventy-six Holstein bull calves were blocked by age (≤8-wk and ≥6-mo-old) and randomly assigned to 1 of 4 treatment groups: control (n=20), castration by banding (n=18), cut-and-clamp surgical castration (n=20), and cut-and-pull surgical castration (n=18). Measurements included electroencephalogram, heart rate variability, infrared thermography, electrodermal activity, and concentrations of serum cortisol and plasma substance P before, during, and within 20min following castration. Electroencephalogram recordings showed desynchronization for all treatments, consistent with increased arousal; yet the magnitude of desynchronization was greatest for 6-mo-old calves castrated by cut-and-clamp. Additionally, older calves in the cut-and-pull group showed greater desynchronization than younger calves in the same group. Based on the heart rate variability analysis, 6-mo-old calves in the control or cut-and-pull castration groups showed greater sympathetic tone than younger calves in the same treatment groups. Overall, younger calves showed lower electrodermal activity than older calves. Regardless of treatment, concentrations of cortisol and plasma substance P were greater in 6-mo-old calves relative to their younger counterparts, indicating a more robust response to all treatments in older calves. In summary, neurohormonal and electroencephalographic stress responses of calves to castration were age-specific. Castration by cut-and-clamp showed the most pronounced stress response in 6-mo-old calves. These findings provide evidence that support welfare policies recommending castration at an early age and the use of analgesic compounds at the time of surgical castration especially in older calves. However, the potential long-term negative consequences of early untreated pain must be considered and warrant further investigation.

Can novel methods be useful for pain assessment of castrated piglets?

“…Stewart et al (2010a and2010b) and Dockweiler et al (2013) described an increase of eye temperature in calves right after castration (up to 10 min) due to an increase in parasympathetic nervous system activity associated with deep visceral pain. Results from these studies suggest that it would be beneficial to investigate eye temperature in a closer time interval to castration increasing the number of samplings but at the same time avoiding repeated handling that would not allow discrimination between pain and handling stress.…”

Effects of sample handling methods on substance P concentrations and immunoreactivity in bovine blood samples

“…Liquid chromatography-tandem mass spectrometry SP [1][2][3][4][5][6][7][8][9][10][11] Parent substance P molecule composed of 11 amino acids SP [3][4][5][6][7][8][9][10][11] Metabolite of substance P composed of the last 9 C-terminal amino acids SP [7][8][9][10][11] Metabolite of substance P composed of the last 5 C-terminal amino acids been evaluated as a response variable that may be more specific for the measurement of pain in animals. [3][4][5][6][7][8][9][10] Substance P is a biologically active peptide that has a role in neural transmission of nociceptive signals from peripheral sites to the CNS.…”

“…[3][4][5][6][7][8][9][10] Substance P is a biologically active peptide that has a role in neural transmission of nociceptive signals from peripheral sites to the CNS. 11 Substance P is released by peptidergic peripheral sensory nerve fibers at central synaptic junctions in the dorsal horn of the spinal cord and at peripheral nerve terminals, where the peptide has a role as a signaling molecule in the transmission of pain impulses and the induction of inflammation and central sensitization.…”

“…The substance P parent molecule is a peptide composed of 11 amino acids with an amidated carboxyl terminus (arginine-prolinelysine-proline-glutamine-glutamine-phenylalaninephenylalanine-glysine-leucine-ethionine-NH 2 ). Enzymes that cleave SP [1][2][3][4][5][6][7][8][9][10][11] include members of the serine and metalloprotease families: angiotensin I-converting enzyme, aminopeptidase, neutral endopeptidase, dipeptidyl peptidase IV, and postproline cleaving enzyme. 13,14 Enzymes of these classes require inhibitors with specific affinity for their catalytic sites; therefore, protection of SP [1][2][3][4][5][6][7][8][9][10][11] from enzymatic degradation may require at least 2 inhibitor types.…”

Refining a ‘toolkit’ for objective assessment of pain and stress in ruminants

“…An increase in plasma PGE 2 was found in cattle that were dehorned (Fraccaro et al, 2013). Substance P had been used in assessing various routine procedures in cattle, such as castration (Coetzee et al, 2008;Dockweiler et al, 2013), electroejaculation (Whitlock et al, 2012), and dehorning however these studies were limited in cattle, and no studies had observed SP response in sheep as an indicator of pain caused by routine husbandry procedures. Hence the lack of homogenous responses in SP and IL-6, and detectable responses in IL-1, β-EP and PGE 2 may not necessarily indicate that these biomarkers are unreliable to detect pain in ruminants if used in other pain models.…”