Pre-slaughter Transport Research Articles

How do crate materials impact the winter transport of broilers?

Pre-slaughter transportation adversely impacts the welfare, meat yield, and quality of broilers, yet the effects of different crate types on broiler chickens during winter remain underexplored. The goal of this study was to investigate the effect of plastic and iron crates in transit on meat quality, carcass, and physiological traits of broiler chickens during winter. A total of 175, 35-day-old Ross 308 male broilers with an average body weight of about 1,708 ± 33.3 g (mean ± standard error of the mean) were picked after 4 hours of feed withdrawal before transport. The control group comprises birds in the farm (n = 15) without transportation at 173 cm2/kg density. The birds were transported into fixed iron (25 birds per crate) and plastic crates (15 birds per crate) with four replicates per crate type at the same 173 cm2/kg densities. The transportation distance was 20 km for 40 min at an average speed of 30-50 km/h early morning at 8:00 am under - 1 ℃ and 47% relative humidity. There was no difference (p>0.05) in carcass traits among the treatments. Concerning meat quality, broilers transported in both crate types exhibited lower (p<0.01) a* values compared to the control group. Additionally, the iron crate group demonstrated higher (p<0.05) b* values for the breast meat compared to the other groups. In terms of blood metabolites, the iron crate group had higher (p<0.05) cortisol, glucose, and lactate levels compared to the control group that did not transport. Broilers transported in the iron crates increase stress levels in terms of higher cortisol, glucose, and lactate contents in the blood plasma compared to untransported broilers during the winter. Therefore, employing plastic crates, which induce significantly reduced cortisol and numerically lower glucose levels compared to iron crates, appears more favorable for animal welfare by mitigating stress.

Evaluation of zinc oxide nanocomposites and L-ascorbic acid on meat quality during transport induced stress in birds of Sonali breed

The study assessed the efficacy of phytofabricated zinc oxide nanoparticles (CF-ZnONPs) and L-ascorbic acid in alleviating pre-slaughter transport induced stress in birds of Sonali breed (Cross bred of Rhode Island Red cocks and Fayoumi hens). A total of 120 birds were divided into four groups: negative control (T1) which were loaded in vehicle but not transported, Positive control (T2) birds were transported without any prior supplementation, T3 and T4 birds were transported with prior supplementation (a day before transportation) of CF-ZnONPs @100 µg/ml and L-ascorbic acid @82 µg/ml in drinking water. Results obtained observed significant reduction in live weight, meat colour and pH but increased drip loss percentage in T2 group. Significantly elevated H/L ratio was recorded in all transported groups. Increased cortisol and TSH levels and decreased thyroid hormones, Triiodothyronine and thyroxin (T3 and T4) levels were recorded in T2 group. However, supplementation with CF-ZnONPs and L-ascorbic acid notably reversed these adverse effects, restoring meat quality and other metabolic profiles. Notably, ascorbic acid exhibited greater efficacy, suggesting its superior role in mitigating transportation-induced stress. Overall, these findings highlight the importance of antioxidant supplementation in alleviating transport induced stress in birds.

Study on the effects of pre-slaughter transport stress on water holding capacity of pork: Insights from oxidation, structure, function, and degradation properties of protein

This work systematically investigated the effects of pre-slaughter transport stress on pork water holding capacity (WHC) during aging from the perspectives of oxidation, structure, function, and degradation properties of protein. Pigs were randomly divided into three-hour transport (Transport-induced stress, T group) and three-hour transport followed by three-hour resting (Control, TR group). Results demonstrated that T treatment markedly declined pork WHC. Compared with TR group, T group presented increased oxidation levels. Meanwhile, T treatment exacerbated the shift of protein secondary structure from α-helix to random coil and protein unfolding levels. The decreased solubility, thermal stability, and degraded levels of proteins were also observed in T group. Additionally, muscle contractions of T group were more severe than TR group. This study supported that pre-slaughter transport stress altered physicochemical properties and structures of postmortem muscle proteins, which reduced pork WHC via impairing the interactions between protein and water molecules and changing the muscle fiber structure.

Contents of Macro- and Microelements in Blood Serum and Breast Muscle of Turkey Subjected to Pre-Slaughter Transport for Various Distances.

In this study, the effect of pre-slaughter handling on the content of macro- and micronutrients in blood serum and in the breast muscle of turkeys was assessed. Four different variants of pre-slaughter handling were used in the research: no transport (N-T), transport for a distance of 100 km (T-100), transport for a distance of 200 km (T-200), and transport for a distance of 300 km (T-300). In each of them, 30 female and 30 male turkeys were used. Blood was collected from the birds before slaughter, and samples of the pectoral muscle were collected after slaughter. In the obtained biological material, the content of Mg, P, Ca, Fe, Na and K was analyzed. On the basis of the obtained research results, it can be concluded that the pre-slaughter handling negatively affects the content of macro- and microelements both in the blood serum and in the pectoral muscles of experimental turkeys. Additionally, differences due to the sex of birds were observed.

Modification-Specific Proteomic Analysis Reveals Cysteine S-Nitrosylation Mediated the Effect of Preslaughter Transport Stress on Pork Quality Development.

This study aimed to explore the effects of preslaughter transport stress on protein S-nitrosylation levels and S-nitrosylated proteome in post-mortem pork longissimus thoracis (LT) muscle. Pigs (N= 16) were randomly divided into 3 h transport (high-stress group, HS) and 3 h transport followed by 3 h resting treatments (low-stress control group, LS). Results demonstrated that high transport stress levels induced nitric oxide (NO) overproduction by promoting NO synthase (NOS) activity and neuronal NOS (nNOS) expression, which thereby notably increased protein S-nitrosylation levels in post-mortem muscle (p < 0.05). Proteomic analysis indicated that 133 S-nitrosylation-modified cysteines belonging to 85 proteins were significantly differential, of which 101 cysteines of 63 proteins were higher in the HS group (p < 0.05). Differential proteins including cytoskeletal and calcium-handling proteins, glycolytic enzymes, and oxidoreductase were mainly involved in the regulation of muscle contraction and energy metabolism that might together mediate meat quality development. Overall, this study provided direct evidence for changes in S-nitrosylation levels and proteome in post-mortem muscle in response to preslaughter transport stress and revealed the potential impact of S-nitrosylated proteins on meat quality.

Dietary supplementation of Eucommia leaf extract to growing-finishing pigs alters muscle metabolism and improves meat quality.

The objective of this study was to investigate the influence of dietary supplementation of Eucommia ulmoides leaf extract (ELE) on muscle metabolism and meat quality of pigs with and without pre-slaughter transportation. In a 43-day feeding experiment, a total of 160 pigs with an initial body weight 60.00±2.00 kg were randomly assigned into four groups in a completely randomized design with 10 replicates. Pigs in groups A and C were fed a basal diet and pigs in groups B and D were fed a basal diet supplemented with 0.5% ELE. Pigs were slaughtered with (group B and D) or without (group A and C) pre-slaughter transport. Muscle chemical composition, postmortem glycolysis, meat quality and muscle metabolome were analyzed. Dietary ELE supplementation had no effect on the proximate composition of porcine muscle, but increased free phenylalanine, proline, citruline, norvaline, and the total free amino acids in muscle. In addition, dietary ELE increased decanoic acid and eicosapentaenoic acid, but decreased heptadecanoic acid, oleic acid, trans-oleic acid, and monounsaturated fatty acids in muscle. Meat quality measurement demonstrated that ELE improved meat water holding capacity and eliminated the negative effects of pre-slaughter transport on meat cooking yield and tenderness. Dietary ELE reduced muscle glycolytic potential, inhibited glycolysis and muscle pH decline in the postmortem conversion of muscle to meat and increased the activity of citrate synthase in muscle. Metabolomics analysis by liquid chromatographic tandem mass spectrometric showed that ELE enhanced muscle energy level, regulated AMP-activated protein kinase (AMPK) signaling, modulated glycogenolysis/glycolysis, and altered the metabolism of carbohydrate, fatty acids, ketone bodies, amino acids, purine, and pyrimidine. Dietary ELE improved meat quality and alleviated the negative effect of preslaughter transport on meat quality by enhancing muscle oxidative metabolism capacity and inhibiting glycolysis in postmortem muscle, which is probably involved its regulation of AMPK.

Effect of loading density and weather conditions on animal welfare and meat quality of slaughter pigs.

There are several factors that affect the welfare and meat quality of pigs during pre-slaughter transport. Among various factors, the effects of weather conditions and loading density were studied. A total of 3,726 finishing pigs were allotted to one of nine groups arranged in a 3 × 3 factorial design according to the weather conditions (low temperature [LT], under 10°C; normal temperature [NT], 10°C-24°C; high temperature [HT], upper 24°C), and loading density (low density [LD], upper 0.43 m2/100 kg; normal density [ND], 0.37-0.43 m2/100 kg; high density [HD], under 0.37 m2/100 kg). Each treatment group follow as: LTLD, LTND, LTHD, NTLD, NTND, NTHD, HTLD, HTND, HTHD. In terms of carcass composition, pigs had the highest carcass weight and backfat thickness at LT. Comparing the HD transport to the ND transport, the meat quality indicated a lower pH and more drip loss. The incidence rate of pale, soft, exudative (PSE) pork was high in the order of the HD, LD, and the ND transport (20%, 9%, and 2%, respectively). The HT transport showed the lowest pH and greatest L* value under the given weather conditions. Pigs transported under the HTHD and LTLD conditions had the greatest rates of PSE pork (40% and 20%, respectively). Pigs exposed to HD transport had the shortest laying time and the highest overplap behavior. The LDLT transport pigs had a shorter laying time than the LDNT and LDHT transport pigs. In conclusion, too high or too low density transport is generally not excellent for meat quality or animal welfare, however it is preferable to transport at a slightly low density at high temperature and at a slightly high density at low temperature.

Efficacy of creatine nitrate supplementation on redox status and mitochondrial function in pectoralis major muscle of preslaughter transported broilers

This study was purposed to investigate the efficacy of dietary creatine nitrate (CrN) supplementation on redox status and mitochondrial function in pectoralis major (PM) muscle of broilers that experienced preslaughter transport. A total of 288 Arbor Acres broilers (28-day-old) were randomly assigned into five dietary treatments, including a basal diet or the basal diet supplemented with 600 mg/kg guanidinoacetic acid (GAA), 300, 600, or 900 mg/kg CrN for 14 days, respectively. On the transportation day, the basal diet group was divided into two groups on average, resulting in six groups. The control group was transported for 0.5 h and the other groups for 3 h (identified as Control, T3h, GAA600, CrN300, CrN600, and CrN900 group, respectively), and all crates were randomly placed on the truck travelling at an average speed of 80 km/h. Our results showed that GAA600 and CrN treatments decreased the muscle ROS level and MDA content (P < 0.05) and increased the mitochondrial membrane potential (P < 0.001), as well as a higher mRNA expression of avUCP (P < 0.001) and lower mRNA expressions of Nrf2 (P < 0.001), Nrf2 and PGC-1α (P < 0.05) compared with T3h group. Meanwhile, the mRNA and protein expressions of Nrf1, TFAM, and PGC-1α in CrN600 and CrN900 groups were lower than those in the T3h group (P < 0.05). Conclusively, dietary supplementation with GAA and CrN decreased muscle oxidative products and enhanced mitochondrial uncoupling mechanism and mtDNA copy number, which relieved muscle oxidative damage and maintained mitochondrial function.

Effects of journey duration and temperature during pre-slaughter transport on behaviour of cull sows in lairage

This observational field study investigated the effects of journey duration, temperature, and waiting duration before unloading on the behaviour of 562 cull sows during lairage from 23 commercial loads. Each load consisted of sows originating from more than one herd, thus experiencing variable pre-slaughter transport and management. In lairage, sows were mixed in groups of 25, involving animals from all journey durations (min-max: 0.8–8.4 h) and video monitored for 60 min. At first most sows were in upright position (approximately 80–90%), decreasing to 30–40% after 30 min. After 60 min, 42% of the sows had initiated aggression (min-max: 0–43 events/sow), 28% had been subjected to aggressive behaviour (min-max: 0–14 events/sow), and 36% s were observed drinking (min-max: 0–16 events/sow). Several significant interactions were found between journey duration, the average temperature in the vehicle and lairage pen (averages: 4.3–26.2 °C) and waiting duration before unloading (min-max: 3–25 min). For example, after short journeys, sows exposed to higher temperature carried out more aggressive behaviour, while a higher temperature after long journeys was associated with more lying and less drinking. This suggests that the sows prioritised lying behaviour over drinking and establishing a dominance hierarchy. We discuss how the results may be interpreted as behavioural signs of fatigue, but further studies, for example involving quantification of physiological and motivational indicators, are needed to clarify this. Irrespectively, the present findings suggest that a stay in a lairage pen, as part of the pre-slaughter logistic chain, involves challenges for the welfare of the cull sows.

Effect of Pre-Slaughter Transport Stress on Protein S-Nitrosylation Levels of Pork during Postmortem Aging.

This study aimed to investigate the effect of pre-slaughter transport stress on the protein S-nitrosylation levels of pork during 0, 3, and 6 days of aging. Pigs (N = 16) were randomly selected and divided into two treatments: 3 h transport (transport stress, TS) and 3 h transport followed by 3 h resting (control, CON). Results showed that the TS group at 0 and 3 days presented a higher nitric oxide synthase (NOS) activity and neuronal NOS (nNOS) expression than the CON group (P < 0.05). Additionally, nNOS was not only abundantly localized in the membrane but also observed in small amounts in the cytoplasm. The immunoblot of overall S-nitrosylated protein showed that protein S-nitrosylation levels in the TS group were greater than in the CON group during postmortem aging (P < 0.05). This work can deliver novel insights into the mechanism of meat quality changes in response to pre-slaughter stress.

Intracellular Calcium Overload and Activation of CaMKK/AMPK Signaling Are Related to the Acceleration of Muscle Glycolysis of Broiler Chickens Subjected to Acute Stress.

The current study investigated the effect of preslaughter transport on stress response and meat quality of broilers and explored the underlying mechanisms involved in the regulation of muscle glycolysis through calcium/calmodulin-dependent protein kinase kinase (CaMKK)/AMP-activated protein kinase (AMPK) signaling. Results suggested that transport induced stress responses of broilers and caused PSE-like syndrome of pectoralis major muscle. Preslaughter transport enhanced the mRNA expressions of glycogen phosphorylase and glucose transporters, as well as the activities of glycolytic enzymes, which accelerated the breakdown of glycolytic substrates and the accumulation of lactic acid. In addition, acute stress induced abnormal intracellular calcium homeostasis by disrupting calcium channels on the cell membrane and sarcoplasmic reticulum, which led to the activation of CaMKK and promoted AMPK phosphorylation. This study provides evidence that the intracellular calcium overload and the enhancement of CaMKK/AMPK signaling are related to the accelerated muscle glycolysis of broiler chickens subjected to acute stress.

The Effect of Space Allowance During Pre-Slaughter Transport of European Quail Breeders on Welfare, Carcass Traits and Meat Quality

The objective was to evaluate whether space allowance during pre-slaughter transport of European breeding quail affects welfare, carcass traits and meat quality. A total of 248 quails (body weight = 344.90 ± 2.09 g) were used. During pre-transport, the quails were fasted for 5 hours and 30 minutes. The poultry were caught and placed in plastic transport crates with an area of 0.40 m2. The treatments consisted of a different space allowance in each crate: 22, 28, 34 or 40 quails per crate. Immediately upon arrival at the slaughterhouse, the quails were stunned. During bleeding, blood samples were collected. The carcasses were individually weighed. The meat quality was measured. Data were analysed using the effects of space allowance during transport of quails and pickup truck as dependent variables. Death on arrival increased as the space allowance in transport crates decreased (p=0.08). Glucose and uric acid levels were not significantly different between groups (p≥0.14). The cold carcass weight presented the maximum value when the crates contained 31 quails (p=0.03). The meat pH, intensity of red, intensity of yellow and cooking losses were not different between groups (p≥0.12). The meat lightness value presented the maximum value when the crates contained 31 quails (p=0.04). In view of the above, the number of European breeding quails transported in crates must not exceed 30 animals.

Dietary creatine nitrate enhances muscle creatine loading and delays postmortem glycolysis of broilers that experienced preslaughter transport.

This study investigated the attenuating effects of dietary creatine nitrate (CrN), a novel form of creatine, on energy expenditure and rapid glycolysis in pectoralis major (PM) muscle of broiler induced by preslaughter transport. A total of 288 Arbor Acres broilers (28 day old) were randomly assigned into five dietary treatments, including a basal diet or the basal diet supplemented with 600 mg/kg guanidinoacetic acid (GAA), 300, 600, or 900 mg/kg CrN for 14 d, respectively. On the day of transportation, the broilers from basal diet group were divided into two equal groups: one group was transported for 0.5 h (Control group) and the other group was transported for 3 h (T3h group). Meanwhile, the birds from GAA and CrN supplementation groups were transported for 3 h (identified as GAA600, CrN300, CrN600, and CrN900 group, respectively). The results demonstrated that dietary supplementation of GAA or CrN from 28 to 42 d of age did not significantly affect the growth performance, carcass traits, and textural characteristics (P > 0.05) in PM muscle of transported broilers. Compared with T3h group, GAA600, CrN600, and CrN900 groups increased the pH45min (P < 0.01), and CrN600, CrN900 groups decreased the cooking loss (P < 0.05) of PM muscle. Meanwhile, the muscle of GAA600, CrN600, and CrN900 groups showed a higher glycogen content (P < 0.01) and a lower lactic acid content (P < 0.01). GAA600 and all CrN treatments enhanced muscle Cr content and reduced AMP/ATP ratio (P < 0.01). In addition, GAA600 and all CrN treatments downregulated the relative mRNA expression levels of LKB1 and AMPKα2 (P < 0.001) and the protein expression of p-AMPKαThr172 compared with the T3h group (P < 0.01). All CrN treatments showed lower protein expression levels of LKB1 and p-LKB1Thr189 than those of the T3h group (P < 0.05). In summary, dietary supplementation with GAA and CrN enhanced the content of muscle creatine, and inhibited transport-induced activation of LKB1/AMPK pathway, which is beneficial for delaying rapid muscle glycolysis and improving meat quality.

Overexpression of Heat Shock Protein 70 Ameliorates Meat Quality of Broilers Subjected to Pre-Slaughter Transport at High Ambient Temperatures by Improving Energy Status of Pectoralis Major Muscle and Antioxidant Capacity.

The induction of heat shock protein 70 (HSP70) potentially mediates meat-quality development under stress conditions. To investigate the effects and mechanism of HSP70 on the meat quality of the pectoralis major (PM) muscles of broilers exposed to pre-slaughter transport, a total of 168 broilers were intraperitoneally injected with L-glutamine (Gln) or saline. Twenty-four hours later, broilers were subjected to transport or held under normal living conditions. The results indicated that acute Gln supplementation significantly increased HSP70 expression in the PM of transported broilers (p < 0.05). The overexpression of HSP70 significantly alleviated the decreases in muscle pH and water-holding capacity and improved the shrinking of muscle fibers induced by transport (p < 0.05). HSP70 induction increased ATP content, decreased the activities of glycolytic enzymes, and lowered the phosphorylation level of AMP-activated protein kinase in transported broilers (p < 0.05). In addition, the overexpression of HSP70 greatly increased total superoxide dismutase and the total antioxidant capability and decreased the levels of reactive oxygen species, malonaldehyde, and carbonyls in the PM of transported broilers (p < 0.05). Overall, this work indicated that HSP70 could effectively improve the meat quality of transported broilers by improving the energy status, inhibiting glycolytic influx, and restoring redox homeostasis.

Acute stress deteriorates breast meat quality of Ross 308 broiler chickens by inducing redox imbalance and mitochondrial dysfunction.

This study investigated the effects of acute stress on breast meat quality, redox status, and mitochondrial function in pectoralis major (PM) muscle of broilers. A total of 168 broiler chickens (42-d-old, Ross 308) were randomly divided into control (CON) and preslaughter transport (T) treatments. A broiler was an experimental unit. Each treatment consisted of 84 broilers, and they were put in 12 crates with 7 broilers each. Broilers in the T group were transported according to a designed protocol, and the CON broilers were kept in crates under normal living conditions before slaughtering. Based on the meat quality traits assessed at postmortem 24 h, all PM muscles of the transported broilers were further classified into normal (T-NOR) and pale, soft, and exudative (PSE)-like (T-PSE) groups for the determination of redox status in PM muscle and isolated mitochondria, energy metabolites, mitochondrial electron transport chain complexes activities, as well as mitochondrial function-modulating genes expression. Compared with CON, the extent of lipid peroxidation as well as protein oxidation were significantly increased in both PM muscles and mitochondria in T-PSE (P < 0.05), whereas not in T-NOR. Higher activities of glutathione peroxidase, total superoxide dismutase, and Cu-Zn superoxide dismutase were observed in PM muscle of T-NOR broilers when compared with CON (P < 0.05). Preslaughter transport increased the generation of reactive oxygen species, as well as enhanced antioxidant capacity in PM mitochondria of broilers (P < 0.05). Compared with CON, the ATP content, activities of complexes I and III, as well as relative mitochondrial membrane potential and swelling were significantly decreased in T-PSE (P < 0.05), whereas no significant changes in either ATP content or complex I activity were observed in T-NOR. Preslaughter transport enhanced the mRNA expression of regulators involved in the glutathione system, thioredoxin 2 system, and mitochondrial biosynthesis in PM muscle of broilers (P < 0.05). Moreover, we noticed a more evident enhancement effect in T-NOR than in T-PSE (P < 0.05). Overall, this work indicates that acute stress-induced redox imbalance and mitochondrial dysfunction have significant implications for the development of PSE-like meat.

Effects of Rumen-Protected Creatine Pyruvate on Meat Quality, Hepatic Gluconeogenesis, and Muscle Energy Metabolism of Long-Distance Transported Beef Cattle

Pre-slaughter long-distance transport resulted in a rapid depletion of muscle glycogen and led to a higher rate of dark, firm and dry (DFD) meat. Therefore, enhancing muscle glycogen reserves is critical for beef cattle prior to transportation. Creatine pyruvate (CrPyr) can provide simultaneous pyruvate and creatine and both are proven to promote the glycogen reserves. This study aimed to investigate the effects of transport treatment and dietary supplementation of rumen-protected (RP)-CrPyr on the meat quality, muscle energy metabolism, and hepatic gluconeogenesis of beef cattle. Twenty 18 month-old male Simmental crossbred cattle (659 ± 16 kg) were allotted 4 treatments based on a 2 × 2 factorial arrangement with two RP-CrPyr levels (140 g/d or 0 g/d) and two transport treatments (12 h or 5 min): ST_CrPyr0, ST_CrPyr140, LT_CrPyr0 and LT_CrPyr140. Three cattle per group were slaughtered after 30 days of feeding. The interaction of transport and RP-CrPyr had a significant effect on the muscle pH45 min, redness, glycogen content, GP, and AMP level (P &amp;lt; 0.05). Compared with short-distance transport, long-distance transport increased the muscle pH45 min value, redness, yellowness, drip loss, creatine level (P &amp;lt; 0.05), decreased muscle glycogen content, glycolytic potential (GP), and liver glucose amount (P &amp;lt; 0.05). Supplementation of RP-CrPyr decreased the activities of creatine kinase and lactate dehydrogenase in serum, muscle pH24 h value, redness, yellowness, lactate content, AMP level, and AMP/ATP (P &amp;lt; 0.05), increased the muscle glycogen content, GP, hexokinase activity, ATP and ADP levels, and ATP/ADP, liver pyruvate and glucose contents, activity of pyruvate carboxylase in the liver of cattle than those in the nonsupplemented treatments (P &amp;lt; 0.05). These results indicated that dietary RP-CrPyr supplementation might be favorable to improve meat quality and regulatory capacity of energy metabolism of beef cattle suffering long-distance transport followed with recovery treatment by increasing muscle glycogen storage, energy supply, and hepatic gluconeogenesis.

Potential of Natural Anesthetic Ocimum basilicum Essential Oil and Eugenol in the Preslaughter Transport of Nile Tilapia Oreochromis niloticus and its Effect on Fillet Quality

ABSTRACT This study evaluated the fillet quality parameters and the fatty acid profile of Nile tilapia subjected to transport with essential oil of Ocimum basilicum and eugenol. Fish was distributed in five treatments: N: non-transported; C: transported with water only; A: water + ethanol; E: water + eugenol; and M: water + O. basilicum. The anesthetics prevented the decrease of the fillet pH. The colorimetry a* (red) was higher for the fish fillets transported with ethanol. The water loss due to dripping was higher in fish transported in water + ethanol. The water loss due to thawing was lower in the nontransported fish fillets. The non-transported fish fillets presented a higher margaric acid content. In general, the fatty acid profile was not altered in its composition, showing that the use of eugenol and O. basilicum essential oil did not change the final quality of the fillet.

Dietary guanidineacetic acid supplementation ameliorated meat quality and regulated muscle metabolism of broilers subjected to pre-slaughter transport stress by metabolomics analysis

Pre-slaughter transport stress could induce multiple comprehensive variations in physiological and metabolic parameters of broilers. However, the entire metabolomics of pre-slaughter transport stress and supplementation of exogenous energy regulatory substances on broilers is still poorly understood. The metabolome characteristics of broilers subjected to 3 h pre-slaughter transport stress combined with 1,200 mg/kg guanidinoacetic acid (GAA1,200) supplementation were analyzed using gas chromatography-mass spectrometry (GC−MS) in this study. The results showed that, compared to the control group (no transport), 3 h pre-slaughter transport stress (T3h) decreased creatine (Cr), phosphocreatine (PCr) and adenosine triphosphate (ATP), and increased adenosine diphosphate (ADP), adenosine monophosphate (AMP) and the ratio of AMP to ATP in pectoralis muscle (PM) of broilers by high performance liquid chromatography (HPLC) analysis. However, GAA1,200 supplementation reversed the negative effects induced by 3 h pre-slaughter transport stress. Besides, GAA1,200 supplementation elevated mRNA expression of creatine transporter in PM. Our metabolomics approaches demonstrated that 38 and 48 significant metabolites were separately identified between the control group and T3h group, and T3h group and 3 h pre-slaughter transport stress combined with GAA1,200 supplementation group using the standard of variable importance in the projection values >1 and P < 0.05. Among these, the metabolites involved in amino acid metabolism (alanine, glycine, serine, threonine, cysteine , methionine, phenylalanine, tyrosine, and tryptophan), oxidative stress (3-methylhistidine, 1-methylhistidine and glutathione), non-protein amino acid (citrulline) metabolism, and energy metabolism (Cr, PCr, sarcosine, and glycocyamine) were confirmed through pathway enrichment analysis, which could be chosen as suitable candidate targets for further analysis of the effects of exogenous energy substances on broilers subjected to transport stress.

PSXI-28 Effect of pre-slaughter transport stress on carcass weight, rumen fermentation and bacterial community of growing goats

Abstract This study evaluated the effects of pre-slaughter transport stress on the rumen fermentation and bacterial community of growing meat goats. Fifty-four male Spanish growing meat goats (28.9 ± 4.5) were stratified by body weight and randomly assigned into three treatment groups (n = 18 per treatment; 1) No transport stress (CON), 2) Transport stress for 30 mins (LS), and 3) Transport stress for 3 h (HS). Blood samples were collected before and after transport to estimate plasma cortisol concentrations. At the end of the experiment, the goats were slaughtered to determine the carcass weight and to collect rumen ruminal content for pH, 16 sRNA gene sequencing, and volatile fatty acid profile. The Linear discriminant analysis (LDA) effect size and the functional profiling software (PICRUst) were used to estimate the differentially abundant taxa and predicted the functional potential of the microbial community, respectively. Compared to CON, both LS and HS increased (P &amp;lt; 0.01) plasma cortisol concentrations (27.5 vs. 130.1 and 117.7 ng/ mL), no differences were observed in hot carcass weight and VFA profile (P &amp;gt; 0.05). Rumen pH was lower (P &amp;lt; 0.05) in HS compared to CON or LS (6.44 vs 6.75 or 6.77). Compared to CON, LS reduced the relative abundance of Ruminococcaceae UCG 014 (LDA = 4.20; P = 0.01), whereas no effect was observed for HS. Compared to CON, predicted microbial functions associated with the immune system, translation, and enzyme activities were downregulated by LS while that of energy metabolism was downregulated by HS. Compared to HS, the predicted microbial functions associated with immune and digestive systems were downregulated by LS. This study demonstrated that LS transport stress has a more pronounced effect than long-term exposure on the rumen bacterial community and predicted functional potential in growing meat goats.

Effects of salinity gradients on the skin and water microbial community and physiological responses of tilapia (Oreochromis niloticus) in the pre‐slaughter

This study investigated the use of salt as a mitigating agent for bacterial contamination and physiological responses of tilapia in a simulation of pre-slaughter transport. Bacteria concentration, haematological parameters and muscle dehydration were evaluated. Adult tilapia (568 ± 141 g) were fasted for 24 h and subjected to a simulation of transport for 4 h in four salinities: 0, 7, 14 and 21 g of salt L−1. The concentration of 21 g of salt L−1 resulted in the lowest concentration of aerobic mesophilic heterotrophic bacteria on the skin of tilapia and in the transport water. Salinity did not influence the haematological parameters of haematocrit, monocytes, eosinophils, basophils, haemoglobin and mean corpuscular haemoglobin concentration. The concentrations of 14 and 21 g of salt L−1 had the lowest plasma protein values and led to lymphopaenia and neutrophilia. The concentration of 7 g of salt L−1 had values similar to baseline level for lymphocyte, neutrophil, white blood cell counts and plasma protein. Hyperglycaemia and thrombocytopaenia occurred in all treatments. Increased dehydration of muscle tissue with increased salinity was observed. The concentration of 7 g of salt L−1 promoted the fewest physiological changes. However, it is recommended the transport at high salinity of 21 g of salt L−1 for bacterial control.