Auditory brainstem responses in weaning pigs and three ages of sows

Authors: CHAPEL, NICHOLE - Purdue University; THOMOVSKY, STEPHANIE - Purdue University; LUCAS, JEFFREY - Purdue University; KUSHIRO-BANKER, TOKIKO - Purdue University; RADCLIFFE, JOHN - Purdue University; STEWART, KARA - Purdue University; Lay Jr, Donald

Submitted to: Translational Animal Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/2/2019
Publication Date: 10/10/2019
Citation: Chapel, N.M., Thomovsky, S.A., Lucas, J.R., Kushiro-Banker, T., Radcliffe, J.S., Stewart, K.R., Lay Jr, D.C. 2019. Auditory brainstem responses in weaning pigs and three ages of sows. Translational Animal Science. 3(4):1416–1422. doi:https://doi.org/10.1093/tas/txz123.
DOI: https://doi.org/10.1093/tas/txz123

Interpretive Summary: Commercial swine farms can become loud, particularly on farms with mechanical ventilation. In the United States, over 75% of sows and gilts are maintained in total confinement with strictly mechanically ventilated air. The noise level in operations routinely exceeds 90 dB and can reach over 100 dB. Environmental noise can have negative effects on behavior, production, and metabolism, with swine regarded as being particularly sensitive to noise. Sows are affected by environmental noise as sows respond best to piglets if they communicate louder than the current environment. This communication barrier may be related to piglet crushing, but sows’ ability to hear piglet calls during crushing is rarely considered in the literature. Auditory brainstem responses can provide a reliable technique for measuring animal hearing and have been used extensively in other species. Auditory brainstem responses rely on measuring brainstem activity in response to a series of clicks or tones and can be performed on subjects under sedation. This technique can allow for relatively rapid testing of hearing in pigs at various ages with easy, reliable data available the same day. The first objective of this study was to successfully measure auditory brainstem responses in pigs of varying ages. The second objective was to determine if older sows have hearing loss when compared to weaning age pigs with the goal of evaluating if some pigs in commercial swine operations have decreased hearing ability. Data show that auditory brainstem responses can be successfully measured in weaning through older adult commercial swine, making them a potential avenue to research hearing ability in swine without the need for extensive pig behavioral training. Some sows cannot hear normally at 90 dB, which has serious implications for pig welfare. Future research should focus on understand the influence of pig hearing current welfare issues in the swine industry. A possible avenue to manage this problem would be the development of quieter fans for farm facilities. These data could provide a useful tool to producers and researchers alike in decreasing piglet mortality, increasing handling ease of sows, and further minimizing welfare concerns associated with hearing loss in pigs.

Technical Abstract: Objectives: To successfully measure auditory brainstem responses in pigs and measure if pig hearing diminishes with age in a mechanically ventilated barn. Materials and methods: Pigs of 4 age groups (weaning, n = 7; gilts, n = 5; 2nd and 3rd parity, n = 5; 5th parity & up, n =5) were anesthetized and placed in a sound dampening box. Auditory brainstem responses (ABR) were performed on sows using 1,000 clicks at two decibel (dB) levels: 90 and 127 dB sound pressure level. Latencies and amplitudes of waves I through V were measured and interpeak latencies for waves I-III, III-V, and I-V were calculated. Results: Five pigs (three 2nd and 3rd parity, and two 5th parity and above) had no detectable waves at either decibel. Sows in 2nd and 3rd parities had very few distinguishable waves, with only wave I and II present in two sows. Amplitudes of waves I and V increased with increased dB (P < .001). Increasing dB decreased the latency of each of the recorded waves (P < .01) Implications: The vast majority of commercial swine are raised in noisy barn environments; it is possible that these environments directly affect the ability for pigs to hear and normal hearing development in this population of animals. Hearing has a significant effect on swine welfare. Hearing is integral to successful animal handing and during moments of animal-to-animal communication. Hearing is a considerable welfare issue on farms and ways to decrease pig hearing loss should be considered.