Effects of acute heat stress on salivary metabolites in growing pigs: an analysis using nuclear magnetic resonance-based metabolomics profiling

Abstract

Heat stress (HS) causes adverse impacts on pig production and health. A potential biomarker of HS is required to predict its occurrence and thereby better manage pigs under HS. Information about the saliva metabolome in heat-stressed pigs is limited. Therefore, this study was aimed to investigate the effects of acute HS on the saliva metabolome and identify metabolites that could be used as potential biomarkers. Growing pigs (n = 6, 3 boars, and 3 gilts) were raised in a thermal neutral (TN; 25°C) environment for a 5-d adaptation period (CON). After adaptation, the pigs were first exposed to HS (30°C; HS30) and then exposed to higher HS (33°C; HS33) for 24 h. Saliva was collected after adaptation, first HS, and second HS, respectively, for metabolomic analysis using 1 H-nuclear magnetic resonance spectroscopy. Four metabolites had significantly variable importance in the projection (VIP > 1; p < 0.05) different levels in TN compared to HS groups from all genders (boars and gilts). However, sex-specific characteristics affected metabolites (glutamate and leucine) by showing the opposite results, indicating that HS was less severe in females than in males. A decrease in creatine levels in males and an increase in creatine phosphate levels in females would have contributed to a protective effect from protein degradation by muscle damage. The results showed that HS led to an alteration in metabolites related to energy and protein. Protection from muscle damage may be attributed to the alteration in protein-related metabolites. However, energy-related metabolites showed opposing results according to sex-specific characteristics, such as sex hormone levels and subcutaneous fat layer. This study had shown that saliva samples could be used as a noninvasive method to evaluate heat-stressed pigs. And the results in this study could be contributed to the development of a diagnostic tool as a noninvasive biomarker for managing heat-stressed pigs.

Anti-Bordetella bronchiseptica effects of targeted bacteriophages via microbiome and metabolic mediated mechanisms

“…Comprehensive metabolomics provides information on body metabolic state and how that status varies in various environmental circumstances 20 , 42 . Therefore, the enriched metabolism pathways in the PC, BN, and AT treatments may give further information about pigs requirements, which can be supplemented in their diets to reduce the adverse side effects of B. bronchiseptica infection.…”

Filling gaps in animal welfare assessment through metabolomics

“…In terms of feasibility of sampling, biofluids such as urine, stool, and saliva can be collected non-invasively, whereas blood and tissues' collection are much more complicated and may be arduous, therefore qualified personnel is required (84). Changes in metabolome of saliva, serum, and adipose tissue were used to study the effect of heat stress in pigs (38,40,41). Both biofluids and tissues were considered to gain a global view on metabolic processes and elucidate the effects of feed deprivation in salmonid fish (37) and in an integrated multi-omics study aimed at ascertaining the effects of the finishing forage on metabolic pathways related to AW and meat quality in bovine (35).…”

“…For tissues, the sample representativeness may be an issue because organs may be described and respond regio-specifically; for example, the liver presents five different topographic lobes characterized by different levels of some enzyme systems expression, as well as the kidney consists of medulla, cortex, and many cell types with different structures and roles (89). Generally, 1-100 mg of tissue and 10-100 µl of biofluids are sufficient (34,37,41,90), although the amount relies on the type of the analytical platform used for the analysis.…”

Selection of appropriate biomatrices for studies of chronic stress in animals: a review

“…Cow Blood [14], saliva [14,15], urine [16], milk [17], feces [18] Sheep Blood [19], saliva [19], urine [20], feces [19] Pig Blood [21], saliva [22,23], urine [24], feces [25] Fish Blood [26], respiratory vapor [27] Chronic Cow Hair [28], hooves and claws [29] Sheep Wool [30] Pig Hair [31] Fish Scales [32], fins [33] Table 2. Use of corticosterone as a biomarker in previous studies of stress in animals…”