Effects of cold stress on growth performance, serum biochemistry, intestinal barrier molecules, and adenosine monophosphate-activated protein kinase in broilers

Intermittent mild cold acclimation ameliorates intestinal inflammation and immune dysfunction in acute cold-stressed broilers by regulating the TLR4/MyD88/NF-κB pathway

To investigate the potential protective effect of prior cold stimulation on broiler intestine induced by acute cold stress (ACS). A total of 384 one-day-old broilers were divided into control (CON), ACS, cold stimulation Ⅰ (CS3+ACS), and cold stimulation Ⅱ (CS9+ACS) groups. Broilers in CON and ACS groups were reared normally, and birds in CS3+ACS and CS9+ACS groups were reared at 3℃ and 9℃ below CON group for 5 h, respectively, on alternate days from d 15 to 35. Broilers in ACS, CS3+ACS, and CS9+ACS groups were subjected to 10℃ for 24 h on d 43. Eventually, small intestine tissues were collected for histopathological observation and indexes detection. The results showed that intestinal tissues in all ACS-broilers exhibited inflammatory cell infiltrates, microvilli disruption, reduced villus length in jejunum and increased crypt depth in jejunum and ileum. Whereas these phenomena were relatively light in CS3+ACS group. Compared to CON group, mRNA expression of the TLR4/MyD88/NF-κB pathway-related genes (TLR4, MyD88, NF-κBp65, COX-2, iNOS, PTGEs, TNF-α), Th1/Th17-derived cytokines (IL-1β, IL-2, IL-8, IL-12, IFN-γ, IL-17), and HSPs (HSP40, HSP60, HSP70, HSP90) was upregulated (P < 0.05), and that of Th2-deviated cytokines (IL-4, IL-6, IL-10, IL-13) and IκBα was downregulated (P < 0.05) in small intestine in almost all ACS-broilers. Compared to ACS group, mRNA expression of most of the TLR4/MyD88/NF-κB pathway-related genes, Th1/Th17-derived cytokines, and HSPs was downregulated and that of Th2-derived cytokines was upregulated in CS3+ACS group (P < 0.05). Protein expression levels of TLR4, MyD88, p-p65/p65, p-IκBα/IκBα, IKK, TNF-α, IL-1β, IL-10, and HSPs were similar to their mRNA expression. The concentration of sIgA and activities of CAT, SOD, and GSH-px were decreased and MDA and H2O2 were increased in ACS and CS9+ACS groups compared to CON group (P < 0.05). Therefore, cold stress caused oxidative stress and inflammation, leading to gut immune dysfunction; while mild cold stimulation at 3℃ below normal rearing temperature alleviated cold stress-induced intestinal injure and dysfunction by modulating the TLR4/MyD88/NF-κB pathway in broilers.

Effects of intermittent cold stimulation on growth performance, meat quality, antioxidant capacity and liver lipid metabolism in broiler chickens

Intermittent cold stimulation (ICS) enhances broilers' resistance to cold stress. Nonetheless, further research is needed to investigate the underlying mechanisms that enhance cold stress resistance. A total of 160 one-day-old male Ross 308 broilers were randomly divided into 2 groups (CC and CS5), with the CC group managing temperature according to the standard for broiler growth stages, while the CS5 group were subjected to cold stimulation at a temperature 3℃ lower than the CC group for 5 h, every 2 d from 15 to 35 d. Sampling was conducted at 36 d (36D), 50 d (50D) and after acute cold stress for 24 h (Y24). First, we examined the effects of ICS on broiler growth performance, meat quality, antioxidant capacity, and lipid metabolism. The results demonstrated that ICS enhanced the performance of broilers to a certain degree. Specifically, the average weight gain in the CS5 group was significantly higher than that of the CC group, and the feed conversion ratio significantly decreased compared to CC at 4 W and 6 W (P ≤ 0.05). Compared with the CC group, cold stimulation significantly reduced drip loss, shearing force, and yellowness (a* value) of chicken meat, while significantly increased redness (b* value) (P ≤ 0.05). At Y24, the levels of T-AOC and GSH-PX in the serum of the CS5 group were significantly higher than those of the CC group, while the level of MDA was significantly lower (P ≤ 0.05). The content of TG, FFA, and VLDL in the serum of the CS5 group was significantly elevated, whereas the level of TC and HDL was significantly lower (P ≤ 0.05). In addition, we further explored whether AMPK-mTOR pathway is involved in the regulation of changes in lipid metabolism and the possible regulatory mechanisms downstream of the signaling pathway. The results showed that ICS significantly upregulated the expression levels of AMPK mRNA and protein in the liver of the CS5 group at 36D and Y24, while significantly down-regulating mTOR (P ≤ 0.05). Compared with the CC group, ICS significantly down-regulated the mRNA expression levels of lipid synthesis and endoplasmic reticulum stress-related genes (SREBP1c, FAS, SCD, ACC, GRP78 and PERK) at 36D and Y24, while significantly up-regulating the mRNA expression levels of lipid decomposition and autophagy-related genes (PPAR and LC3) (P ≤ 0.05). In addition, at Y24, the protein expression levels of endoplasmic reticulum stress-related genes (GRP78) in the CS5 group were significantly lower, while autophagy-related genes (LC3 and ATG7) were significantly higher (P ≤ 0.05). ICS can affect meat quality and lipid metabolism in broilers, and when broilers are subjected to acute cold stress, broilers trained with cold stimulation have stronger lipid metabolism capacity.

Effects of cold stress on physiologic metabolism in the initial phase and performance of broiler rearing

This study aimed to investigate the effects of 8 h of cold stress (18 °C) every day in broiler chicks during the first 7 days of rearing on crop filling analysis, yolk sac consumption, digestive and immune organs weights, and physiological metabolism at seven days and performance between 1 and 35 days. Cobb500 male broiler chickens (n = 274) were randomly assigned to two treatments. The treatments consisted of varying environmental temperatures during the first week post-housing. Chicks were reared at a thermoneutral temperature (32 °C) or under cold stress (18 °C) for 8 h/day during the first week, and both groups were subsequently reared at a thermoneutral temperature for 8-35 days. The thermoneutral group reached 90% full crop after 48 h of housing (P < 0.05), while the cold-stressed group had more empty crops at 2 h and 48 h after housing (P < 0.05). The chick cloacal temperature was not affected by the treatments (P > 0.05). Additionally, the treatment did not affect serum amylase and corticosterone levels, feed intake, body weight gain, or feed conversion ratio (P > 0.05, while the cold-stressed group had elevated heterophil/lymphocyte count at day 7 (P < 0.05). The thermoneutral group showed higher viability (%) at 7 and 35 days and a higher production factor at 35 days (P < 0.05). Broiler chickens under cyclic cold stress experienced decreased yolk sac absorption during the first week and increased feed intake and feed conversion ratio after 35 days of rearing. Viability was also lower in the cold-stressed group. An appropriate strategy to minimize these adverse effects is to rear the chicks in a thermoneutral environment during the first week.

Intermittent cold stimulation affects energy metabolism and improves stress resistance in broiler heart

To investigate the effect of intermittent cold stimulation on cardiac energy metabolism and cold resistance of broilers, 288 broilers were divided into 3 groups: control group (CC) and 2 cold stimulation groups (CS3 and CS9). The CS3 and CS9 groups received cold stimulation at temperatures of 3°C and 9°C lower than CC group for 5 h from d 15 to 35. Three groups were subjected to acute cold stress (ACS) of 10°C for 12 and 24 h at 44 d. Performance, cardiac histopathological changes, heat shock proteins (HSPs), and lipid metabolism levels were measured. Results showed that the performance was not different among groups at 22 and 29 d (P > 0.05), but the mRNA levels of Acyl CoA synthase long-chain family member 1 (ACSL1) and acyl-coenzyme oxidase (ACO) in CS group were upregulated compared to CC group (P < 0.05). At 36 d, the performance of the CS3 group was better than the other 2 groups, myocardial structure was normal and other lipid metabolism indexes, except for peroxisome proliferator-activated receptor coactivator 1α (PGC-1α) levels, were similar to those of CC group (P > 0.05). The myocardial fiber disorder, Triglyceride (TG), and leptin (LEP) contents were significantly lower in CS9 group than in CC and CS3 groups at 36 d (P < 0.05). The HSP protein levels were significantly higher in CS group than in CC group before ACS (P < 0.05). After 24 h of ACS, the mRNA of lipid metabolism genes, the protein levels of HSP40 and HSP60, and the contents of TG and LEP in the CS3 group were upregulated compared to other groups. The CC and CS9 groups showed myocardial structure was destroyed, with lower TG and LEP levels compared to before ACS (P < 0.05). Therefore, cold stimulation at 3°C lower than the normal feeding temperature for 5 h did not impair performance but can increase the resistance of broilers to ACS by promoting lipid metabolism.

The Effect of Low Temperature on Laying Performance and Physiological Stress Responses in Laying Hens

The present study investigated the effect of low temperature on laying performance, egg quality, body temperature, yolk malondialdehyde, yolk corticosterone, and serum biochemistry in laying hens. A total of 40 laying hens (Hy-Line Brown) aged 36 weeks were housed in one of two environmental chambers kept at 12 ± 4.5 °C (low temperature) or 24 ± 3 °C (normal temperature) for 4 weeks. Low vs. normal temperature significantly increased (p < 0.05) live body weight, feed intake, and feed conversion ratio in laying hens. Skin surface temperature, but not rectal temperature, was decreased in laying hens exposed to low vs. normal temperature. Hens exposed to low temperature laid an intense eggshell color compared with those raised in a normal temperature. Malondialdehyde concentrations in yolk were increased in low-temperature-exposed laying hens compared with those at normal temperature conditions, but this effect was only noted on day 7, post the low-temperature exposure (p = 0.04). Finally, low vs. normal temperature increased the concentrations of total cholesterol and triglyceride in serum. Collectively, this study indicates that exposure to low temperature in laying hens initially disrupted antioxidant system and altered lipid metabolism in laying hens without inducing stress responses.

Effect of Environmental and Farm-Associated Factors on Live Performance Parameters of Broilers Raised under Commercial Tropical Conditions

Although temperature, relative humidity, and farm-associated factors are known to affect broiler live performance, data about the impact of these variables under commercial operations are still scarce. This study aimed to evaluate the effect of temperature, relative humidity, a thermal humidity index, management, and farm-associated factors on BW, BW gain, feed conversion ratio (FCR), and mortality of broilers raised to 35 d under commercial tropical conditions. The data analyzed included performance records of Ross 308 AP broiler flocks placed between 2018 and 2020. Environmental monitoring information was obtained from electronic sensors that captured data hourly from 80 flocks in 29 farms. Farm-associated factors were gathered using a survey of 86 farms. Three data analyses were conducted in parallel. Correlation analyses, one-way ANOVA, and machine learning techniques were employed. Results indicated that BW and BW gain were reduced, and FCR worsened (p < 0.001) up to 21 d when chickens were mainly exposed to temperatures 2.5 °C lower than the recommended optimums for each age period. At the same time, mortality at 28 and 35 d increased. In conclusion, all farm-associated factors affected chicken live performance. Variable importance analysis indicated that performance results at 14 and 21 d were significant to predict BW at 35. At the same time, sex, distance between the hatchery and farm, and farm altitude accounted for the most significant contributions from the farm-associated factors.

Acer truncatum leaves extract modulates gut microbiota, improves antioxidant capacity, and alleviates lipopolysaccharide-induced inflammation in broilers

This study investigated the appropriate way of dietary Acer truncatum leaves (ATL) addition, the effect of disease prevention and its mechanism of action. In experiment 1, 192 Arbor Acres broilers were assigned to 4 treatment groups, fed with basal diets containing 2% bran, replacing it with primary and fermented ATL, and additional 0.3% ATL extract to the basal diet for 42 d, respectively. In experiment 2, 144 broilers were assigned to 3 treatment groups for 21-d trial: (1) C-N group, basal diets, and injected with 0.9% (w/v) sterile saline; (2) C-L group, basal diets, and injected with lipopolysaccharide (LPS); (3) T-L group, ATL diets and injected with LPS. In experiment 1, ATL significantly decreased the index of abdominal fat at 42 d (P < 0.05). ATL extract had a better ability to improve antioxidant capacity and reduce inflammatory levels among all treatment groups, which significantly decreased the content of MDA in the liver and ileum mucosa at 21 d, and increased the expression of IL-10 and Occludin in jejunal mucosa at 42 d (P < 0.05). In experiment 2, ATL significantly increased the level of T-AOC in the liver, decreased the expression of NF-κB in the jejunal mucosa and ileum mucosa (P < 0.05), and restored LPS-induced the changed level of CAT in jejunal mucosa, the expression of IL-6, Claudin-1, and ZO-1 in jejunal mucosa and IL-1β in ileum mucosa (P < 0.05). Analysis of gut microbiota indicated that ATL enhanced the abundances of Bacteroidota and reduced the proportion of Firmicutes (P < 0.05), and the changed levels of T-AOC in body, IL-1β, IL-6, IL-10, and NF-κB in jejunum mucosa and propionic acid in cecal were associated with gut microbiota. Collectively, our data showed that the extract of ATL had a better antioxidant and anti-inflammatory effects than primality and fermented. Extraction of ATL modulated intestinal microbiota, and had a protective effect on oxidative stress, inflammation, and intestinal barrier function in broilers challenged with LPS.

Intermittent and Mild Cold Stimulation Maintains Immune Function Stability through Increasing the Levels of Intestinal Barrier Genes of Broilers

In order to improve the adaptability of broilers to low-temperature environments and their ability to resist acute cold stress (ACS), 240 one-day-old broilers were selected and randomly divided into three groups. The control treatment (CC) group was raised at the conventional feeding temperature from 1-43 days (d), the cold stimulation treatment (CS) group was kept at 3 °C below the temperature of CC at 1 d intervals for 3 and 6 h from 15 to 35 d, namely, CS3 and CS6, respectively. Then, all broilers were kept at 20 °C from 36 to 43 d. ACS was then carried out at 44 d, and the ambient temperature was dropped to 10 °C for 6 h. The study investigated the production performance, as well as levels of intestinal barrier genes (including Claudin-1, E-cadherin, Occludin, ZO-1, ZO-2 and Mucin2), secretory IgA in duodenum and jejunum, and immunoglobulins (IgA and IgG) in serum. The results showed that IMCS could increase the daily weight gain and decrease the feed conversion ratio. During IMCS, the expression levels of intestinal barrier genes were up-regulated and the content of secretory IgA was increased. When IMCS ceased for one week, the level of immunoglobulins in serum stabilized, and the expression levels of Occludin, ZO-2 and Mucin2 still maintained high levels. After ACS, broilers that received IMCS training maintained high levels of intestinal barrier genes and secretory IgA.

Acute cold stress induces intestinal injury via CIRP-TLR4-IRE1 signaling pathway in pre-starter broilers

BACKGROUND

Cold stress is a common environmental stress in broiler chicks. Cold-inducible RNA-binding protein (CIRP) is a conserved cold shock protein that can regulate inflammatory response through Toll-like receptor 4 (TLR4). The mechanism that how CIRP involves in the regulation of cold stress in broilers remains unclear.

METHODS AND RESULTS

In this study, 360 7-day-old healthy male SZ901 chicks were selected and randomly allocated to four groups, and then subjected to acute cold exposure at the ambient temperature of 12 ± 1 °C for 0 h, 4 h, 8 h, and 12 h, respectively. After cold exposure, abdominall skin temperature, gene expression of CIRP-TLR4-IRE1 signaling pathway in ileum mucosa, and small intestinal structure were measured. The results showed that cold exposure decreased abdominall skin temperature, upregulated the gene expression of endoplasmic reticulum stress (ERS) markers IRE1, inflammatory factors IL-1β, IL-6, IL-10, TNF-α, and tight junction proteins ZO-1 and Occludin in ileum of chicks compared with the control group with no (0 h) cold exposure. Compared with the control group, a long time cold exposure upregulated the gene expression of CIRP, TLR4, GRP78, NF-κB in ileum mucosa, and decreased the villus height and V/C of small intestine.

CONCLUSIONS

The above results suggest that acute cold stress induces endoplasmic reticulum stress via upregulating the gene expression of CIRP-TLR4-IRE1 signaling pathway, and results in the structural damage of chick intestine.

Effects of cold stress on growth performance, carcass traits and tibia attributes in broiler chickens with thiram-induced dyschondroplasia

The objective of this study was to investigate the effect of cold stress (CS) on growth performance and tibia attributes in broiler chickens with thiram-induced dyschondroplasia (TD). Four hundred 10-day-old male broilers were randomly allocated into four groups including, NT0: normal temperature (NT) without thiram; NT50: NT + thiram; CS0: CS without thiram; and CS50: CS + thiram in a completely randomised. The birds in CS groups were placed at a constant temperature of 15 ± 1°C during 11-20 days. Thiram (50 mg/kg) was added to the diet during 11-14 days to induce TD. Results showed that main effects of CS and thiram significantly decreased body weight and daily weight gain during 11-42 days (p < 0.05). Feed intake in the thiram50 group was significantly lower than the group thiram0 during 25-42 days (p < 0.05). Feed conversion ratio in CS birds was significantly more than NT group during 25-42 days (p < 0.05). On day 16, tibia width (TW) and TW to tibia length (TL) ratio were significantly higher in CS chicks compared to the NT group. TW was significantly higher in thiram50 group than thiram0 group (p < 0.05). On day 19, TL in CS chicks was significantly shorter than NT (p < 0.05). On day 23, growth plate width (GPW) in thiram50 group was significantly higher than thiram0 birds. In general, thiram increased tibial GPW and CS decreased TD severity as well as decreased growth performance in broilers.

Effects of dietary chlorogenic acid on intestinal barrier function and the inflammatory response in broilers during lipopolysaccharide-induced immune stress

Immune stress exerts detrimental effects on growth performance and intestinal barrier function during intensive animal production with ensuing serious economic consequences. Chlorogenic acid (CGA) is used widely as a feed additive to improve the growth performance and intestinal health of poultry. However, the effects of dietary CGA supplementation on amelioration of the intestinal barrier impairment caused by immune stress in broilers are unknown. This study investigated the effects of CGA on growth performance, intestinal barrier function, and the inflammatory response in lipopolysaccharide (LPS) mediated immune-stressed broilers. Three hundred and twelve 1-day-old male Arbor Acres broilers were divided randomly into 4 groups with 6 replicates of thirteen broilers. The treatments included: i) saline group: broilers injected with saline and fed with basal diet; ii) LPS group: broilers injected with LPS and fed with basal diet; iii) CGA group: broilers injected with saline and feed supplemented with CGA; and iv) LPS+CGA group: broilers injected with LPS and feed supplemented with CGA. Animals in the LPS and LPS+CGA groups were injected intraperitoneally with an LPS solution prepared with saline from 14 d of age for 7 consecutive days, whereas broilers in the other groups were injected only with saline. LPS induced a decrease in feed intake of broilers during the stress period, but CGA effectively alleviated this decrease. Moreover, CGA inhibited the reduction of villus height and improved the ratio of villus height to crypt depth in the duodenum of broilers 24 and 72 h after LPS injection. In addition, dietary CGA supplementation significantly restored the expression of cation-selective and channel-forming Claudin2 protein 2 h after LPS injection in the ileum. LPS enhanced the expression of tumor necrosis factor-α (TNF-α) and interleukin-1β (IL-1β) in the small intestine, but this enhancement was blocked by CGA supplementation. The expression of interleukin-10 (IL-10) increased with LPS injection and CGA promoted the production of IL-10. CGA addition downregulated the expression of intestinal interleukin-6 (IL-6) of broilers under normal rearing conditions. However, CGA supplementation upregulated the expression of IL-6 of broilers 72 h after LPS injection. The data demonstrate that dietary supplementation with CGA alleviates intestinal barrier damage and intestinal inflammation induced by LPS injection during immune stress thereby improving growth performance of broilers.

Heat Shock Protein Response to Stress in Poultry: A Review

Compared to other animal species, production has dramatically increased in the poultry sector. However, in intensive production systems, poultry are subjected to stress conditions that may compromise their well-being. Much like other living organisms, poultry respond to various stressors by synthesising a group of evolutionarily conserved polypeptides named heat shock proteins (HSPs) to maintain homeostasis. These proteins, as chaperones, play a pivotal role in protecting animals against stress by re-establishing normal protein conformation and, thus, cellular homeostasis. In the last few decades, many advances have been made in ascertaining the HSP response to thermal and non-thermal stressors in poultry. The present review focuses on what is currently known about the HSP response to thermal and non-thermal stressors in poultry and discusses the factors that modulate its induction and regulatory mechanisms. The development of practical strategies to alleviate the detrimental effects of environmental stresses on poultry will benefit from detailed studies that describe the mechanisms of stress resilience and enhance our understanding of the nature of heat shock signalling proteins and gene expression.

Effects of Lactobacillus plantarum fermented Shenling Baizhu San on gut microbiota, antioxidant capacity, and intestinal barrier function of yellow-plumed broilers

The current study focused on the effects of Shenling Baizhu San (SLBZS) fermented by Lactobacillus plantarum (L. plantarum) on gut microbiota, antioxidant capacity, and intestinal barrier function of yellow-plumed broilers. Our results showed that the content of ginsenoside Rb1 was the highest when SLBZS were inoculated with 3% L. plantarum and fermented at 28°C for 24 h. One-day-old male broilers were divided into five treatment groups. Treatment consisted of a basal diet as a control (Con), 0.1% unfermented SLBZS (U-SLBZS), 0.05% fermented SLBZS (F-SLBZS-L), 0.1% fermented SLBZS (F-SLBZS-M), and 0.2% fermented SLBZS (F-SLBZS-H). On days 14, 28, and 42, six chickens from each group were randomly selected for blood collection and tissue sampling. The results showed that the addition of 0.1% fermented SLBZS could significantly increase average daily feed intake (ADFI) and average daily gain (ADG), and decrease feed conversion ratio (FCR) of broilers. The addition of 0.1 and 0.2% fermented SLBZS significantly increased the lymphoid organ index of broilers on day 28 and 42. The addition of 0.1 and 0.2% fermented SLBZS could improve the antioxidant capacity of broilers. Moreover, the addition of 0.1 and 0.2% fermented SLBZS could significantly increase the villus height/crypt depth of the ileum, and significantly increase the expression of tight junction. In addition, fermentation of SLBZS increase the abundance of Coprococcus, Bifidobacterium and Bilophila in the gut of broilers. These results indicate that the supplementation of fermented SLBZS in the diet could improve the growth performance, lymphoid organ index, antioxidant capacity, and positively affect the intestinal health of broilers.

Effects of Acute Cold Stress after Intermittent Cold Stimulation on Immune-Related Molecules, Intestinal Barrier Genes, and Heat Shock Proteins in Broiler Ileum

Cold stress will have a negative impact on animal welfare and health. In order to explore the effect of intermittent cold stimulation training on the cold resistance of broilers. Immune-related and intestinal barrier genes were detected before and after acute cold stress (ACS), aiming to find an optimal cold stimulation training method. A total of 240 1-day-old Ross broilers (Gallus) were divided into three groups (G1, G2, and G3), each with 5 replicates (16 chickens each replicate). The broilers of G1 were raised at normal temperature, while the broilers of G2 and G3 were treated with cold stimulation at 3 °C lower than the G1 for 3 h and 6 h from 15 to 35 d, respectively, at one-day intervals. At 50 d, the ambient temperature for all groups was reduced to 10 °C for six hours. The results demonstrated that before ACS, IL6, IL17, TLR21, and HSP40 mRNA levels in G3 were apparently down-regulated (p < 0.05), while IL8 and Claudin-1 mRNA levels were significantly up-regulated compared with G1 (p < 0.05). After ACS, IL2, IL6, and IL8 expression levels in G3 were lower than those in G2 (p < 0.05). Compared to G2, Claudin-1, HSP90 mRNA levels, HSP40, and HSP70 protein levels were increased in G3 (p < 0.05). The mRNA levels of TLR5, Mucin2, and Claudin-1 in G2 and IL6, IL8, and TLR4 in G3 were down-regulated after ACS, while IL2, IL6, and IL17 mRNA levels in G2 and HSP40 protein levels in G3 were up-regulated after ACS (p < 0.05). Comprehensive investigation shows that cold stimulation at 3 °C lower than the normal feeding temperature for six hours at one day intervals can enhanced immune function and maintain the stability of intestinal barrier function to lessen the adverse effects on ACS in broilers.

Ecological footprint of poultry production and effect of environment on poultry genes

The growing demand for poultry meat and eggs has forced plenty of changes in poultry production in recent years. According to FAO, the total number of poultry in the world in 2019 was 27.9 billion. About 93% of them are chickens. The number of chickens has doubled in the last 30 years. These animals are the most numerous in Asia and America. Hence, poultry meat is the most frequently obtained type of meat in recent years (it is 40.6% of the obtained meat). Focusing on lowering production costs has led to process optimization, which was possible by improving the use of animal genetics, optimizing feeding programs, and new production technologies. The applied process optimization and production increase practices may also lead to a deterioration of the ecological balance through pollution with chemical substances, water consumption, and natural resources. The aim of this paper was to review the current state of knowledge in the field of the ecological footprint of poultry production and the impact on environmental genes.

Effects of Low-Ambient-Temperature Stimulation on Modifying the Intestinal Structure and Function of Different Pig Breeds

Simple Summary

Low ambient temperature resulted in the body’s cold stress response, while local wild boars in the middle-temperate zone performed better than commercial pigs. Therefore, three breeds—Large White (LW) pigs, a local Mashen (MS) pig breed and Jinfen White (JFW) pigs, a hybrid breed from wild boar—were investigated in an artificial climate chamber. The results implicated that low-ambient-temperature stimulation increased trypsin activity in duodenal chyme and promoted inflammatory response in Mashen pigs. The cold-resistance mechanism of MS pigs should be explored to reduce hogs’ stress caused by low-ambient-temperature stimulation.

Abstract

Ambient temperature (Ta) fluctuation is a key factor affecting the growth performance and economic returns of pigs. However, whether the response of intestinal structure and function are related to pig breeds in low Ta has not been investigated yet. In this study, Large White (LW) pigs, Jinfen White (JFW) pigs and Mashen (MS) pigs were raised in artificial climate chambers under normal Ta (25 °C) and low Ta (4 °C) for 96 h. Afterwards, the decrease in body temperature and complete blood counts (CBC) of all pigs were measured. Hematoxylin–eosin, immunohistochemical staining, qPCR and ELISA were used to investigate their intestinal mucosa integrity and inflammatory response. The results showed that MS pigs could maintain a normal body temperature and villus structure after 4 °C stimulation compared with those of LW and JFW pigs. Villus height and villus height/crypt depth of MS pigs were significantly higher than those of LW and JFW pigs at 4 °C. Low-Ta stimulation increased the digestion of carbohydrates of all pigs. Meanwhile, low Ta enhanced the activity of lipase in LW pigs and increased trypsin activity in MS and JFW pigs. Furthermore, low-Ta stimulation significantly downregulated the protein of tight junction and upregulated the mRNA expression of inflammatory cytokines in MS pigs. MS pigs also showed stronger spleen immune function at 4 °C. These results indicated that the local MS pig breed had stronger intestinal function in low Ta by producing a stronger inflammatory response, which lays the foundation for further study on the mechanism of cold tolerance in pigs.

Non-Targeted Metabolomic Analysis of Chicken Kidneys in Response to Coronavirus IBV Infection Under Stress Induced by Dexamethasone

Stress in poultry can lead to changes in body metabolism and immunity, which can increase susceptibility to infectious diseases. However, knowledge regarding chicken responses to viral infection under stress is limited. Dexamethasone (Dex) is a synthetic glucocorticoid similar to that secreted by animals under stress conditions, and has been widely used to induce stress in chickens. Herein, we established a stress model in 7-day-old chickens injected with Dex to elucidate the effects of stress on IBV replication in the kidneys. The metabolic changes, immune status and growth of the chickens under stress conditions were comprehensively evaluated. Furthermore, the metabolic profile, weight gain, viral load, serum cholesterol levels, cytokines and peripheral blood lymphocyte ratio were compared in chickens treated with Dex and infected with IBV. An LC-MS/MS-based metabolomics method was used to examine differentially enriched metabolites in the kidneys. A total of 113 metabolites whose abundance was altered after Dex treatment were identified, most of which were lipids and lipid-like molecules. The principal metabolic alterations in chicken kidneys caused by IBV infection included fatty acid, valine, leucine and isoleucine metabolism. Dex treatment before and after IBV infection mainly affected the host’s tryptophan, phenylalanine, amino sugar and nucleotide sugar metabolism. In addition, Dex led to up-regulation of serum cholesterol levels and renal viral load in chickens, and to the inhibition of weight gain, peripheral blood lymphocytes and IL-6 production. We also confirmed that the exogenous cholesterol in DF-1 cells promoted the replication of IBV. However, whether the increase in viral load in kidney tissue is associated with the up-regulation of cholesterol levels induced by Dex must be demonstrated in future experiments. In conclusion, chick growth and immune function were significantly inhibited by Dex. Host cholesterol metabolism and the response to IBV infection are regulated by Dex. This study provides valuable insights into the molecular regulatory mechanisms in poultry stress, and should support further research on the intrinsic link between cholesterol metabolism and IBV replication under stress conditions.

Dietary Glucose Ameliorates Impaired Intestinal Development and Immune Homeostasis Disorders Induced by Chronic Cold Stress in Pig Model

Endotherms are easily challenged by chronic cold stress. In this study, the development and injury of the small intestine in the Min pig model and Yorkshire pig model under chronic cold stress, and the molecular mechanisms by which glucose supplementation reduces small intestinal mucosal damage were investigated. The results showed that morphological structure lesions of the jejunal mucosa and ileal mucosa were visible in Yorkshire pigs under chronic cold stress. Meanwhile, the Occludin mRNA and protein expression in jejunal mucosa of Yorkshire pigs was decreased. Chronic cold stress enhanced the expression of Toll-like receptor 4 (TLR4), the myeloid differentiation main response 88 (MyD88), nucleotide-binding domain and leucine-rich repeat protein 3 (NLRP3), cleaved caspase-1, mature-IL-1β, and high-mobility group box 1 (HMGB 1) mRNA and protein expression in jejunal mucosa of Yorkshire pigs, whereas the mRNA and protein of Bax was triggered in ileal mucosa. In Min pigs, no such deleterious consequences were observed. Dietary glucose supplementation ameliorates small intestinal mucosal injury, declined TLR4 and MyD88 expression in jejunal mucosa. In conclusion, chronic cold stress induced the small intestinal mucosa damage in Yorkshire pigs, whereas glucose supplementation mitigated the deleterious effects of chronic cold stress on the small intestine.

Effects of ambient temperature on the growth performance, fat deposition, and intestinal morphology of geese from 28 to 49 days of age

This study was conducted to investigate the effects of ambient temperature on the growth performance, fat deposition, and intestinal morphology of geese from 28 to 49 d of age. A total of 120 twenty-eight-day-old geese were randomly allotted to 5 environmentally controlled chambers with ambient temperatures set at 18, 21, 24, 27, and 30°C from 28 to 49 d of age, respectively. The feed intake, 49 d body weight, and weight gain decreased linearly or quadratically (P < 0.05) as ambient temperature increased and declined to a minimum when the temperature increased to 30°C. The feed/gain showed a linear or quadratic (P < 0.05) increasing response to increasing temperature. According to broken-line regression, the upper critical levels of ambient temperature from 28 to 49 d of age for weight gain and feed intake were 25.19 and 23.97°C, respectively. As ambient temperature increased from 18 to 30°C, the abdominal fat weight, abdominal fat rate, and subcutaneous fat thickness decreased linearly (P < 0.05) and were accompanied by linearly increasing liver fat content (P < 0.05), but the ambient temperature had no effect on intermuscular fat width or breast muscle fat content (P > 0.05). There were no differences in jejunal, ileal, or cecal morphology for geese raised at 18, 21, 24, 27, and 30°C (P > 0.05). The duodenal villus height showed a linear decreasing response to increasing ambient temperature, but the ambient temperature had no effect on crypt depth, villus width, muscularis thickness, or villus height/crypt depth of the duodenum (P > 0.05). These results indicate that high ambient temperature decreased growth performance and fat deposition and impaired duodenal morphology of geese. Under our experimental conditions, we recommend that the upper critical ambient temperature for geese from 28 to 49 d of age be 25.19°C.

Effects of ambient temperature on growth performance, blood parameter, and fat deposition of geese from 14 to 28 days of age

An experiment was conducted to investigate the effects of ambient temperature on the growth performance, blood parameter, and fat deposition in geese from 14 to 28 d of age in order to establish their optimal temperature requirements. A total of 150 14-day-old geese were allocated randomly to 5 environmentally controlled chambers with ambient temperature set at 18, 21, 24, 27, and 30°C from 14 to 28 d of age, respectively. As ambient temperature increased from 18 to 30°C, the feed intake decreased linearly (P < 0.05) and was accompanied by linearly or quadratically (P < 0.05) decreasing 28-day-old body weight, weight gain, and feed/gain. The upper critical level of ambient temperature from 14 to 28 d of age for 28-day-old body weight and weight gain were 25.83 and 26.17°C, respectively. There were no differences in plasma biochemical parameters or plasma hormones between geese fed at ambient temperature regimen at 18, 21, 24, 27, and 30°C. The abdominal fat weight and abdominal fat rate decreased linearly (P ≤ 0.05) with higher ambient temperature, but the ambient temperature had no effect on subcutaneous fat thickness or intermuscular fat width. It was concluded that the upper critical temperature of the ambient temperature for geese from 14 to 28 d of age was 26.17°C and high ambient temperature could lead to growth depression.

Environmental Stress in Chickens and the Potential Effectiveness of Dietary Vitamin Supplementation

Environmental stressors can promote the vulnerability of animals to infections; it is therefore, essential to understand how stressors affect the immune system, the adaptive capacity of animals to respond, and effective techniques in managing stress. This review highlights scientific evidence regarding environmental stress challenge models and the potential effectiveness of vitamin supplementation. The major environmental stressors discussed are heat and cold stress, feed restriction, stocking density, and pollutants. Much work has been done to identify the effects of environmental stress in broilers and layers, while few involved other types of poultry. Studies indicated that chickens' performance, health, and welfare are compromised when challenged with environmental stress. These stressors result in physiological alterations, behavioral changes, decreased egg and meat quality, tissue and intestinal damage, and high mortalities. The application of vitamins with other nutritional approaches can help in combating these environmental stressors in chickens. Poultry birds do not synthesize sufficient vitamins during stressful periods. It is therefore suggested that chicken diets are supplemented with vitamins when subjected to environmental stress. Combination of vitamins are considered more efficient than the use of individual vitamins in alleviating environmental stress in chickens.

Dietary Eucommia ulmoides Extract Alleviates the Effect of Cold Stress on Chick Growth Performance, Antioxidant and Immune Ability

Simple Summary

The cold stress that chicks suffer from has caused huge losses to the chicken industry. It is very important to find an effective way to alleviate cold stress in chicks. This study was designed to test the hypothesis that dietary Eucommia ulmoides extract alleviates the effect of cold stress on chick growth performance, antioxidants, and immune ability. Interestingly, Eucommia ulmoides extract supplementation improved the growth performance, antioxidant status, and immune response and reduced the organ damage of chicks caused by cold stress, which shows that Eucommia ulmoides extract has potent protective effects against cold stress. These findings will be very beneficial to break down the bottleneck issue of chick production caused by cold stress.

Abstract

This study aimed to investigate the protective value of Eucommia ulmoides extract (EUE) on chicks under cold stress. A total of 21 compounds were identified in EUE using mass spectrometry (LC-MS). Ninety chicks were divided into a control group (CS) fed a basal diet and an experimental group supplemented with EUE, exposed to 10 ± 1 °C for 8 h per day. Results showed, compared with the CS group, the body weights (BW) (p < 0.01) and average daily gains ADG (p < 0.05) of the EUE group were increased throughout the study period. Chicks fed EUE had higher AFI (0–7 d, p < 0.001) and lower feed-to-gain ratios (F/G) (0–15 d, p < 0.001). EUE increased the activities of superoxide dismutase (SOD) (15 d, p < 0.05) and glutathione peroxidase (GSH-Px) (7 d, p < 0.05), whereas it decreased malondialdehyde (MDA) (15 d, p < 0.01). The contents of IgA (7 d, p < 0.05), IgG (7 d; 15 d, p < 0.01), and IgM (15 d, p < 0. 001) were higher in the EUE group. Dietary EUE could also reduce chick organ damage. Overall, EUE as a natural feed additive can improve the growth performance, antioxidant capacity, and immune level, and reduce the organ damage of cold-stressed chicks.

Thermal stress and high stocking densities in poultry farms: Potential effects and mitigation strategies

Environmental changes pose significant threats to agricultural activities particularly animal production. These changes have induced major concerns which will negatively affect the poultry health and productivity under the current climate changes. Moreover, they also alter the immunological status of the exposed birds and make them susceptible to different diseases. The adverse effects of environmental stress also include poor performance of birds (reduced feed intake, growth, feed efficiency, immunity, and egg production) and inferior product quality. The adverse effect of heat stress on different quail breeds like Japanese quail, bobwhite quail, scaled quail, and Gambel's quail ranged from decreased growth rates (11.0-14.5%), body weight (7.7-13.2%), feed intake (6.1-21.6%), feed efficiency (4.3-8.6%), and egg production (6.6-23.3%). Also, birds reared under heat stress (34 °C) had significantly decreased Haugh units by 10.8% and egg weight by 14.3% in comparison with the control group (reared at 22 °C). On the other hand, increasing stoking density from 30 to 45 kg/m² also negatively affected the feed intake and body weight. Recent studies have focused on evaluating the potential adverse effects of different environmental stresses on poultry performance, behavior, welfare, and reproduction. It is imperative to understand better the interaction of different environmental factors and their subsequent effects on avian physiology, to spotlights on the effective management and nutritional strategies to alleviate the adverse effects of different stresses in poultry. This review aims to present a comprehensive overview of physiological manifestations of major environmental stresses including thermal stress (heat and cold stress) and high stocking densities on poultry health and production. Moreover, we have also critically evaluated the scope and efficacy of some potential strategies to mitigate the influences of these environmental stressors in different poultry species.