Guanidinoacetic acid supplementation improves feed conversion in broilers subjected to heat stress associated with muscle creatine loading and arginine sparing

An Assessment of the Effects of Guanidinoacetic Acid on the Performance and Immune Response of Laying Hens Fed Diets with Three Levels of Metabolizable Energy

Different levels of metabolizable energy (ME) and the inclusion of guanidinoacetic acid (GAA) in the diet of 53-week-old Lohmann LSL-CLASSIC hens were used to evaluate its effect on reproductive parameters, egg quality, intestinal morphology, and the immune response. Six diets were used in a 3 × 2 factorial design, with three levels of ME (2850, 2800, and 2750 kcal/kg), and with (0.08%) or without the inclusion of GAA. The addition of GAA to diets with low levels of ME increased (p < 0.05) egg production and egg mass. Moreover, hens fed with 2800 kcal/g without GAA had the highest concentration (p < 0.05) of serum interleukin IL-2, while those fed diets with the same amount of ME but supplemented with 0.08% GAA had the lowest concentration. Finally, the inclusion of 0.08% GAA increased (p < 0.05) the concentration of vascular endothelial growth factor (VEGF), regardless of the ME level in the diet. This study highlights the potential role of GAA in decreasing the energy level of ME (50-100 kcal/g) in the feeding of hens and in the modulation of specific immune responses. Further research is recommended to fully understand the mechanisms of action of GAA on the mechanism target of rapamycin and its relationship with the immune response.

Short Communication: The effect of in ovo creatine monohydrate on early pen use activity in chicks

First-week survival and egg hatchability are lower in chicks from younger broiler breeder hen flocks. Creatine is a naturally occurring compound synthesised from the amino acid arginine or obtained from the diet and is important in the storage and transport of energy. Previous research found an improvement in the hatch rate but no posthatch performance improvements when fertile eggs from young breeder hens were injected with creatine monohydrate (CrM) on embryonic day 14. This pilot study aimed to further investigate the possibility of early posthatch improvements by examining the activity of chicks during the 1st week posthatch. Behaviours were broadly classified as active or inactive, the pen was split into three areas, and the amount of time spent in the heat lamp, feed hopper, or drinker line areas was recorded. Chicks given in ovo CrM spent less time in the heat lamp area over the whole 7 days compared to saline (t = 2.352, P = 0.021) and control groups (t = 3.336, P = 0.003) and more time in the feed hopper area during the first 4 days compared to the control group (t = 2.174, P = 0.033). This finding suggests that creatine may improve energy reserves in young chicks allowing them to spend more time away from the heat lamp.

Interaction effects of glycine equivalent and standardized ileal digestible threonine in low protein diets for broiler grower chickens

OBJECTIVE

This study aims to investigate the interactive effect of a glycine equivalent (Glyequi) and standardized ileal digestible threonine (SID Thr) levels in low crude protein diets on performance, blood biochemistry, pectoral muscular creatine content and oxidative stability of meat in broiler chickens from 21 to 42 days.

METHODS

A total of 1,500, twenty-one-day-old Cobb-Vantress male broiler chickens were distributed in a completely randomized 5×3 factorial arrangement of Glyequi×SID Thr with five replicates of 20 birds each. Fifteen dietary treatments of 16.5% CP were formulated to contain five levels of total Glyequi (1.16%, 1.26%, 1.36%, 1.46%, and 1.56%) and three levels of SID Thr (0.58%; 0.68% and 0.78%).

RESULTS

Interaction effects (p<0.05) of Glyequi and SID Thr levels were observed for weight gain, carcass yield, pectoral muscular creatine content and serum uric acid. Higher levels of Glyequi increased (p = 0.040) weight gain in 0.58% and 0.68% SID Thr diets compare to the 0.78% SID Thr diet. The SID Thr level at 0.68% improved (p = 0.040) feed conversion compared to other SID Thr diets. Levels of Glyequi equal to or above 1.26% in diets with 0.78% SID Thr resulted in birds with higher (p = 0.033) pectoral muscular creatine content. The breast meat yield observed in the 0.68% SID Thr diet was higher (p = 0.05) compared to the 0.58% SID Thr diet. There was a quadratic effect of Glyequi levels for pectoral pectoral muscular creatine content (p = 0.008), breast meat yield (p = 0.030), and serum total protein concentrations (p = 0.040), and the optimal levels were estimated to be 1.47%, 1.35%, and 1.40% Glyequi, respectively. The lowest (p = 0.050) concentration of malondialdehyde in the breast meat was found in 0.68% SID Thr diets at 1.36% Glyequi.

CONCLUSION

The minimum dietary level of Glyequi needed to improve performance in low crude protein diets is 1.26% with adequate SID Thr levels for broiler chickens.

Comparative effects of dietary herbal mixture or guanidinoacetic acid supplementation on growth performance, cecal microbiota, blood profile, excreta gas emission, and meat quality in Hanhyup-3-ho chicken

Phytogenic feed additives are renowned for their growth promotion, gut health enhancement, and disease prevention properties, which is important factors for sustaining prolonged poultry rearing. The study aimed to evaluate the effect of herbal mixture (mixture of ginseng and artichoke) or guanidinoacetic acid (GAA) on growth performance, cecal microbiota, excretal gas emission, blood profile, and meat quality in Hanhyup-3-ho chicken. A total of 360 one-day-old chickens (half males and half females) were allocated into one of 3 dietary treatments (12 replicate cages/treatment; 10 broilers/replicate cage) for 100 d of age. Experimental diets were CON: basal diet; TRT1: basal diet combined with 0.05% herbal mixture; and TRT2: basal diet combined with 0.06% GAA. All birds received a basal diet during the first 30 d, but from d 31 to 100, an experimental diet was supplied. The addition of 0.05% herbal mixture improved the average body weight gain and feed conversion ratio from d 31 to 100 as well as the overall experimental period. The cecal Lactobacillus, Escherichia coli, and Salmonella count remained consistent across all dietary treatments. Blood albumin and Superoxide Dismutase (SOD) levels increased in the herbal mixture supplemented diet. Additionally, there was a notable reduction in excretal NH3 and H2S emissions in the herbal mixture group. Furthermore, the herbal mixture group exhibited increased breast muscle weight, improved breast muscle color, improved water holding capacity, and a decrease in abdominal fat compared to the control group. Additionally, the supplementation of 0.06% GAA did not demonstrate any statistically significant impact on any evaluated parameter throughout the experiment. The results from the present investigation underscore the potential of ginseng together with artichoke extract supplementation as a viable feed additive, conferring improvements in growth performance, feed efficiency, excreta gas emission, meat quality parameters, and defense mechanism against oxidative stress in Hanhyup-3-ho chicken.

Protective effects of Lactobacillus on heat stress-induced intestinal injury in finisher broilers by regulating gut microbiota and stimulating epithelial development

Heat stress (HS) is a critical challenge in broilers due to the high metabolic rate and lack of sweat glands. Results from this study show that implementing a cyclic chronic HS (34 °C for 7 h/d) to finisher broilers decreased the diversity of cecal microbiota and impaired intestinal barrier, resulting in gut leak and decreased body weight (both P < 0.05). These alterations might be related to inflammatory outbursts and the retarded proliferation of intestinal epithelial cells (IECs) according to the transcriptome analysis. Considering the potential beneficial properties of Lactobacillus on intestinal development and function, the protective effects of Lactobacillus rhamnosus (L. rhamnosus) on the intestine were investigated under HS conditions in this study. Orally supplemented L. rhamnosus improved the composition of cecal microbiota and upregulated the transcription of tight junction proteins in both duodenum and jejunum, with a consequent suppression in intestinal gene expressions of pro-inflammatory cytokines and facilitation in digestive capability. Meanwhile, the jejunal villus height of the birds that received L. rhamnosus was significantly higher compared with those treated with the broth (P < 0.05). The expression abundances of genes related to IECs proliferation and differentiation were increased by L. rhamnosus, along with upregulated mRNA levels of Wnt3a and β-catenin in jejunum. In addition, L. rhamnosus attenuated enterocyte apoptosis as indicated by decreased caspase-3 and caspase-9 gene expressions. The results indicated that oral administration with L. rhamnosus mitigated HS-induced dysfunction by promoting intestinal development and epithelial maturation in broilers and that the effects of L. rhamnosus might be dependent of Wnt/β-catenin signaling.

Metabolomics analysis to interpret changes in physiological and metabolic responses to chronic heat stress in Pekin ducks

Heat stress (HS) is a major environmental threat that affects duck production in subtropical and tropical regions, especially in summer. This study aimed to evaluate the physiological and metabolic responses of Pekin ducks to chronic HS conditions via liquid chromatography-mass spectrometry (LC-MS) using a paired-fed (PF) experimental design. On the basis of equivalent feed intake (HS vs. PF), HS significantly reduced growth performance and the percentage of leg and breast muscles, however, markedly increased the percentage of abdominal fat and breast skin fat. Serum metabolomics results revealed that heat-stressed ducks showed enhanced glycolysis and pentose phosphate pathways, as demonstrated by higher glucose 6-phosphate and 6-phogluconic acid levels in the PF vs. HS comparison. HS decreased hepatic mRNA levels of mitochondrial fatty acid β-oxidation-related genes (MCAD and SCAD) compared to the PF group, resulting in acetylcarnitine accumulation in serum. Moreover, HS elevated the concentrations of serum amino acids and mRNA levels of ubiquitination-related genes (MuRF1 and MAFbx) in the skeletal muscle and amino acid transporter-related genes (SLC1A1 and SLC7A1) and gluconeogenesis-related genes (PCK1 and PCase) in the liver compared to the PF group. When compared to the normal control group (NC), HS further decreased growth performance, but it elevated the abdominal fat rate. However, increased mRNA levels of ubiquitination-related genes and serum amino acid accumulation were not observed in the HS group compared to the NC group, implying that reduced feed intake masked the effect of HS on skeletal muscle breakdown and is a form of protection for the organism. These results suggest that chronic HS induces protein degradation in the skeletal muscle to provide amino acids for hepatic gluconeogenesis to provide sufficient energy, as Pekin ducks under HS conditions failed to efficiently oxidise fatty acids and ketones in the mitochondria, leading to poor growth performance and slaughter characteristics.

Effects of guanidinoacetic acid supplementation on liver and breast muscle fat deposition, lipid levels, and lipid metabolism-related gene expression in ducks

Exogenous supplementation of guanidinoacetic acid can mechanistically regulate the energy distribution in muscle cells. This study aimed to investigate the effects of guanidinoacetic acid supplementation on liver and breast muscle fat deposition, lipid levels, and lipid metabolism-related gene expression in ducks. We randomly divided 480 42 days-old female Jiaji ducks into four groups with six replicates and 20 ducks for each replicate. The control group was fed the basal diet, and the experimental groups were fed the basal diet with 400, 600, and 800 mg/kg (GA400, GA600, and GA800) guanidinoacetic acid, respectively. Compared with the control group, (1) the total cholesterol (p = 0.0262), triglycerides (p = 0.0357), malondialdehyde (p = 0.0452) contents were lower in GA400, GA600 and GA800 in the liver; (2) the total cholesterol (p = 0.0365), triglycerides (p = 0.0459), and malondialdehyde (p = 0.0326) contents in breast muscle were decreased in GA400, GA600 and GA800; (3) the high density lipoprotein (p = 0.0356) and apolipoprotein-A1 (p = 0.0125) contents were increased in GA600 in the liver; (4) the apolipoprotein-A1 contents (p = 0.0489) in breast muscle were higher in GA600 and GA800; (5) the lipoprotein lipase contents (p = 0.0325) in the liver were higher in GA600 and GA800; (6) the malate dehydrogenase contents (p = 0.0269) in breast muscle were lower in GA400, GA600, and GA800; (7) the insulin induced gene 1 (p = 0.0326), fatty acid transport protein 1 (p = 0.0412), and lipoprotein lipase (p = 0.0235) relative expression were higher in GA400, GA600, and GA800 in the liver; (8) the insulin induced gene 1 (p = 0.0269), fatty acid transport protein 1 (p = 0.0234), and lipoprotein lipase (p = 0.0425) relative expression were increased in GA400, GA600, and GA800 in breast muscle. In this study, the optimum dosage of 600 mg/kg guanidinoacetic acid improved the liver and breast muscle fat deposition, lipid levels, and lipid metabolism-related gene expression in ducks.

Beyond protein synthesis: the emerging role of arginine in poultry nutrition and host-microbe interactions

Arginine is a functional amino acid essential for various physiological processes in poultry. The dietary essentiality of arginine in poultry stems from the absence of the enzyme carbamoyl phosphate synthase-I. The specific requirement for arginine in poultry varies based on several factors, such as age, dietary factors, and physiological status. Additionally, arginine absorption and utilization are also influenced by the presence of antagonists. However, dietary interventions can mitigate the effect of these factors affecting arginine utilization. In poultry, arginine is utilized by four enzymes, namely, inducible nitric oxide synthase arginase, arginine decarboxylase and arginine: glycine amidinotransferase (AGAT). The intermediates and products of arginine metabolism by these enzymes mediate the different physiological functions of arginine in poultry. The most studied function of arginine in humans, as well as poultry, is its role in immune response. Arginine exerts immunomodulatory functions primarily through the metabolites nitric oxide (NO), ornithine, citrulline, and polyamines, which take part in inflammation or the resolution of inflammation. These properties of arginine and arginine metabolites potentiate its use as a nutraceutical to prevent the incidence of enteric diseases in poultry. Furthermore, arginine is utilized by the poultry gut microbiota, the metabolites of which might have important implications for gut microbial composition, immune regulation, metabolism, and overall host health. This comprehensive review provides insights into the multifaceted roles of arginine and arginine metabolites in poultry nutrition and wellbeing, with particular emphasis on the potential of arginine in immune regulation and microbial homeostasis in poultry.

Inclusion of guanidinoacetic acid in a low metabolizable energy diet improves broilers growth performance by elevating energy utilization efficiency through modulation serum metabolite profile

This study was aimed to explore the elevating energy utilization efficiency mechanism for the potentially ameliorative effect of guanidinoacetic acid (GAA) addition on growth performance of broilers fed a low metabolizable energy (LME) diet. A total of 576 d old broilers were randomly allocated to one of the six treatments: a basal diet (normal ME, positive control, PC), or an LME diet (50 kcal/kg reduction in ME, negative control, NC) supplemented with 0.02%, 0.04%, 0.06%, and 0.08% GAA from 1 to 42 d of age, respectively. The GAA fortification in LME diet linearly or quadratically dropped (P < 0.05) the feed conversion ratio (FCR) from 22 to 42 and 1 to 42 d of age, abdominal fat rate on day 42, serum alanine aminotransferase (ALT) on day 21, and serum creatinine (CREAN) on days 21 and 42, elevated (P < 0.05) breast muscle rate and leg muscle rate on day 42, serum creatine kinase (CK) on days 21 and 42, as well as alkaline phosphatase (ALP), and lactate dehydrogenase (LDH) on day 21. The dietary optimal GAA levels were 0.03%-0.08% based on the best-fitted quadratic models (P < 0.03) of the above parameters. Thus, the PC, LME, and 0.04% GAA-LME groups were selected for further analysis. Serum essential amino acids (EAA) tryptophan, histidine and arginine, non-essential amino acids (NEEA) serine, glutamine and aspartic acid were significantly decreased (P < 0.05), compared to PC diet by LME or 0.04% GAA-LME diet. 0.04% GAA-LME group reversed (P < 0.05) the reduction of arginine, 3-methyhistidine, and 1-methylhistidine by LME diet. Besides, six birds at 28 d of age from LME and 0.04% GAA-LME groups were selected for energy utilization observation in calorimetry chambers. The results demonstrated that 0.04% GAA-LME group significantly improved (P < 0.05) the ME intake (MEI) and net energy (NE) compared to the LME diet. Overall, these findings suggest that 0.04% GAA is the ideal dose of broilers fed the LME diet, which can significantly improve the growth performance and carcass characteristics by modulation of creatine metabolism through elevating serum CK activity and arginine concentration.

Mucosa-associated lymphoid tissue lymphoma translocation protein 1 inhibition alleviates intestinal impairment induced by chronic heat stress in finisher broilers

Heat stress (HS) in poultry has deleterious effects on intestinal development and barrier function, along with inflammatory outbursts. In the present study, chronic HS reduced body weight of broilers and activated mucosa-associated lymphoid tissue lymphoma translocation protein 1 (Malt1) /nuclear factor kappa B (NF-κB) signaling pathways to elicit the inflammatory cytokine response in jejunum. Subsequently, this study investigated the protective effects of the Malt1 inhibitor on the intestine of broilers under HS conditions. The 21-day-old male broilers were allocated to 8 pens housed in HS room (34°C for 7 h/d) until 28 d of age. During this period, 4 birds were selected from each heat-stressed pen and received intraperitoneal injection of 20 mg/kg body weight Mepazine (a Malt1 inhibitor) or the equivalent volume of phosphate buffer saline (PBS) every other day. When compared to PBS broilers, birds received Mepazine injection exhibited increased relative weight and higher villus height in jejunum (both P < 0.05). Mepazine treatment also increased (P < 0.05) the mRNA of zonula occludens-1 (ZO-1), claudin-1, and cadherin 1 of jejunum, which was companied by the reduced caspase-3 transcription under HS condition. Meanwhile, the gene expression levels of toll-like receptor 4 (TLR4), Malt1, NF-κB, interleukin-6 (IL-6), and tumor necrosis factor alpha (TNF-α) in the jejunum were significantly downregulated by Mepazine administration (P < 0.05). Although there were no significant differences in the relative weight of the thymus and bursa, the transcription levels of T helper 1 (Th1)- and Th17-related cytokines were lower in thymus of birds injected with Mepazine. The cytokines of Treg cytokine transforming growth factor beta (TGF-β) and forkhead box protein P3 (Foxp3) in both the thymus and bursa were not influenced. These results suggest that inhibition of Malt1 protease activity can protect intestinal integrity by promoting the production of tight junction proteins and attenuating NF-κB-mediated intestinal inflammation response under HS conditions.

Effects of guanidinoacetic acid supplementation on growth performance, hypothalamus-pituitary-adrenal axis, and immunity of broilers challenged with chronic heat stress

Heat stress can cause systemic immune dysregulation and threaten the health of broilers. Guanidinoacetic acid (GAA) has been shown to be effective against heat stress, but whether it is beneficial for immunity is unclear. Therefore, the effects of dietary GAA supplementation on the immunity of chronic heat-stressed broilers were evaluated. A total of 192 Arbor Acres male broilers (28-day old) were randomly allocated to 4 treatments: the normal control group (NC, 22°C, ad libitum feeding), the heat stress group (HS, 32°C, ad libitum feeding), the pair-fed group (PF, kept at 22°C and received food equivalent to that consumed by the HS group on the previous day), and the GAA group (HG, 32°C, ad libitum feeding; basal diet supplemented with 0.6 g/kg GAA). Samples were collected on d 7 and 14 after treatment. Results showed that broilers exposed to heat stress exhibited a decrease (P < 0.05) in ADG, ADFI, thymus and bursa of Fabricius indexes, and an increase (P < 0.05) in feed conversion ratio and panting frequency, compared to the NC group. Levels of corticotropin-releasing factor, corticosterone (CORT), heat shock protein 70 (HSP70), IL-6, and TNF-α were elevated (P < 0.05) while lysozyme and IgG concentration was decreased (P < 0.05) in the HS group compared with the NC group after 7 d of heat exposure. The concentrations of IgG and IL-2 were decreased (P < 0.05) and CORT was increased (P < 0.05) in the HS group compared with the NC group after 14 d of heat exposure. Noticeably, GAA supplementation decreased the levels of CORT (P < 0.05) and increased the IL-2, IgG, and IgM concentrations (P < 0.05) compared with the HS group. In conclusion, chronic heat stress increased CORT release, damaged immune organs, and impaired the immunity of broilers. Dietary supplementation of 0.6 g/kg GAA can reduce the CORT level and improve the immune function of broilers under heat stress conditions.

N-acetyl-L-cysteine improves the performance of chronic cyclic heat-stressed finisher broilers but has no effect on tissue glutathione levels

1. It was hypothesised that dietary N-acetyl-L-cysteine (NAC) in feed, as a source of cysteine, could improve the performance of heat-stressed finisher broilers by fostering glutathione (GSH) synthesis. GSH is the most abundant intracellular antioxidant for which the sulphur amino acid cysteine is rate limiting for its synthesis.2. In the first experiment, four levels of NAC: 0, 500, 1000 and 2000 mg/kg were added to a diet with a suboptimal level of sulphur amino acids in the finisher phase. In the second experiment, NAC was compared to other sulphur amino acid sources at equal molar amounts of digestible sulphur amino acids. Birds were allocated to four groups: control, 2000 mg/kg NAC, 1479 mg/kg L-cystine, and 2168 mg/kg Ca-salt of 2-hydroxy-4-(methylthio)butanoic acid. A chronic cyclic heat stress model (temperature was increased to 34°C for 7 h daily) was initiated at 28 d of age.3. In the first experiment, growth performance and feed efficiency in the finisher phase were significantly improved by graded NAC. ADG was 88.9, 92.2, 93.7 and 97.7 g/d, and the feed-to-gain ratio was 2.18, 1.91, 1.85 and 1.81 for the 0, 500, 1000 and 2000 mg/kg NAC treatments, respectively. However, liver and heart GSH levels were not affected by NAC. On d 29, liver gene transcript of cystathionine-beta-synthase like was reduced by NAC, which suggested reduced trans-sulphuration activity. The second experiment showed that L-cystine and Ca-salt of 2-hydroxy-4-(methylthio) butanoic acid were more effective in improving performance than NAC.4. In conclusion, N-acetyl-L-cysteine improved dose-dependently growth and feed efficiency in heat-stressed finishing broilers. However, this was not associated with changes in tissue GSH levels, but more likely worked by sparing methionine and/or NAC's and cysteine's direct antioxidant properties.

Dietary Guanidine Acetic Acid Improves Ruminal Antioxidant Capacity and Alters Rumen Fermentation and Microflora in Rapid-Growing Lambs

Guanidine acetic acid (GAA) has been reported to improve growth performance, nutrient utilization, and meat quality in livestock. This study aimed to investigate whether coated GAA (CGAA) in comparison with uncoated GAA (UGAA) could have different effects on rumen fermentation, antioxidant capacity, and microflora composition in the rumen. Seventy-two lambs were randomly arranged in a 2 × 3 factorial experiment design with two diets of different forage type (OH: oaten hay; OHWS: oaten hay plus wheat silage) and three GAA treatments within each diet (control, diet without GAA addition; UGAA, uncoated GAA; CGAA, coated GAA). The whole feeding trial lasted for 120 days. The lambs in the OH group presented lower total volatile fatty acid (VFA), alpha diversity, Firmicutes, NK4A214_group, and Lachnospiraceae_NK3A20_group than those on the OHWS diet in the last 60 days of the feeding stage (p < 0.05). Regardless of what GAA form was added, dietary GAA supplementation increased the total VFA, microbial crude protein (MCP), adenosine triphosphate (ATP), and antioxidant capacity in rumen during lamb feedlotting (p < 0.05). However, molar propionate proportion, acetate:propionate ratio (A:P), and relative Succiniclasticum abundance decreased with GAA addition in the first 60 days of the growing stage, while the molar butyrate proportion and NK4A214_group (p < 0.05) in response to GAA addition increased in the last 60 days of feeding. These findings indicated that dietary GAA enhanced antioxidant capacity and fermentation characteristics in the rumen, but the addition of uncoated GAA in diets might cause some dysbacteriosis of the rumen microbiota.

Effects of feeding guanidinoacetic acid on oxidative status and creatine metabolism in broilers subjected to chronic cyclic heat stress in the finisher phase

Dietary guanidinoacetic acid (GAA) has been shown to affect creatine (Cr) metabolic pathways resulting in increased cellular Cr and hitherto broiler performances. Yet, the impact of dietary GAA on improving markers of oxidative status remains equivocal. A model of chronic cyclic heat stress, known to inflict oxidative stress, was employed to test the hypothesis that GAA could modify bird's oxidative status. A total of 720-day-old male Ross 308 broilers were allocated to 3 treatments: 0, 0.6 or 1.2 g/kg GAA was added to corn-SBM diets and fed for 39 d, with 12 replicates (20 birds each) per treatment. The chronic cyclic heat stress model (34°C with 50-60% RH for 7 h daily) was applied in the finisher phase (d 25-39). Samples from 1 bird per pen were taken on d 26 (acute heat stress) and d 39 (chronic heat stress). GAA and Cr in plasma were linearly increased by feeding GAA on either sampling day, illustrating efficient absorption and methylation, respectively. Energy metabolism in breast and heart muscle was greatly supported as visible by increased Cr and phosphocreatine: ATP, thus providing higher capacity for rapid ATP generation in cells. Glycogen stores in breast muscle were linearly elevated by incremental GAA, on d 26 only. More Cr seems to be directed to heart muscle as opposed to skeletal muscle during chronic heat stress as tissue Cr was higher in heart but lower in breast muscle on d 39 as opposed to d 26. The lipid peroxidation marker malondialdehyde, and the antioxidant enzymes superoxide dismutase and glutathione peroxidase showed no alterations by dietary GAA in plasma. Opposite to that, superoxide dismutase activity in breast muscle was linearly lowered when feeding GAA (trend on d 26, effect on d 39). Significant correlations between the assessed parameters and GAA inclusion were identified on d 26 and d 39 using principal component analysis. To conclude, beneficial performance in heat-stressed broilers by GAA is associated with enhanced muscle energy metabolism which indirectly may also support tolerance against oxidative stress.

Dietary supplementation with synbiotics improves growth performance, antioxidant status, immune function, and intestinal barrier function in broilers subjected to cyclic heat stress

This study investigated the effects of synbiotics supplementation on growth performance, antioxidant status, immune function, and intestinal barrier function in broilers subjected to cyclic heat stress. One hundred and forty-four 22-day-old male broilers were randomly assigned to one of three treatment groups of six replicates each for a 21-day study, with eight birds per replicate. Broilers in the control group were reared at a thermoneutral temperature and received a basal diet. Broilers in the other two heat-stressed groups were fed a basal diet supplemented without (heat-stressed group) and with 1.5 g/kg synbiotic (synbiotic group). One and a half gram of the synbiotic consisted with 3 × 10⁹ colony forming units (CFU) Clostridium butyricum, 1.5 × 10⁹ CFU Bacillus licheniformis, 4.5 × 10¹⁰ CFU Bacillus subtilis, 600 mg yeast cell wall, and 150 mg xylooligosaccharide. Compared with the control group, heat stress increased rectal temperatures at 28, 35, and 42 days of age, respectively (P < 0.05). Birds subjected to heat stress had reduced weight gain, feed intake, and feed efficiency during 22 to 42 days (P < 0.05). In contrast, supplementation with the synbiotic decreased rectal temperature at 42 days of age and elevated weight gain of heat stress-challenged broilers (P < 0.05). Heat-stressed broilers exhibited a lower superoxide dismutase (SOD) activity in jejunal mucosa and a higher malondialdehyde accumulation in serum, liver and jejunal mucosa (P < 0.05), and the regressive SOD activity was normalized to control level when supplementing synbiotic (P < 0.05). Heat stress increased interleukin-1β (IL-1β) and interferon-γ (IFN-γ) levels in serum and IL-1β content in jejunal mucosa of broilers (P < 0.05). Synbiotic reduced IL-1β level in serum of broilers subjected to heat stress (P < 0.05). Compared with the control group, elevated serum diamine oxidase activity and reduced jejunal villus height were observed in broilers of the heat-stressed group (P < 0.05), and the values of these two parameters in the synbiotic group were intermediate (P > 0.05). Heat stress upregulated mRNA abundance of IL-1β and IFN-γ and downregulated gene expression levels of occluding and zonula occluden-1 (ZO-1) in jejunal mucosa of broilers (P < 0.05). The alterations in the mRNA expression levels of jejunal IL-1β and ZO-1 were reversed by the synbiotic (P > 0.05). In conclusion, dietary synbiotics could improve growth performance, antioxidant capacity, immune function, and intestinal barrier function in heat-stressed broilers.

Guanidinoacetic acid supplementation improves intestinal morphology, mucosal barrier function of broilers subjected to chronic heat stress

The current study is designed to investigate dietary guanidinoacetic acid (GAA) supplementation on the growth performance, intestinal histomorphology, and jejunum mucosal barrier function of broilers that are subjected to chronic heat stress (HS). A total of 192 male broilers (28-d old) were randomly allocated to four groups. A chronic HS model (at a temperature of 32 °C and 50%-60% relative humidity for 24 h daily) was applied in the experiment. Normal control (NC, ad libitum feeding, 22 °C), HS group (HS, ad libitum feeding, 32 °C), pair-fed group (PF, received food equivalent to that consumed by the HS group on the previous day, 22 °C), guanidinoacetic acid group (HG, ad libitum feeding, supplementing the basal diet with 0.6 g/kg GAA, 32 °C). The experiment lasted from 28 to 35 and 28 to 42 d of age of broilers. Our results showed that broilers subjected to HS had lower average daily feed intake and average daily gain (P < 0.05), higher feed-to-gain ratio and relative length of the small intestine (P < 0.05), as well as lower relative weight and weight per unit length of the small intestine (P < 0.05). HS damaged the small intestinal histomorphology by decreasing the small intestinal VH and the VH/CD (P < 0.05). Compared with the HS group, supplementation with 0.6 g/kg GAA increased jejunal VH and VH/CD (P < 0.05), but decreased relative weight and relative length of the small intestine (P < 0.05). Moreover, in comparison with NC, HS elevated intestinal permeability (D-Lactic acid concentration and diamine oxidase activity) and mRNA expression levels of interleukin-1β, interleukin-6, and tumor necrosis factor-α (P < 0.05), reduced jejunal mucus thickness, number of goblet cells, IgA + cell density, and mucin2 mRNA expression level of broilers (P < 0.05). Compared with the HS group, dietary GAA elevated jejunal mucus thickness, goblet cell number and IgA+ cell density (P < 0.05), and up-regulated jejunal mRNA expression of interleukin-1β and tumor necrosis factor-α (P < 0.05). In conclusion, HS impaired growth performance, and the intestinal mucosal barrier function of broilers. Dietary supplementation with 0.6 g/kg GAA alleviated HS-induced histomorphology changes of small intestine and jejunal mucosal barrier dysfunction.

Effect of supplemental methyl sulfonyl methane on performance, carcass and meat quality and oxidative status in chronic cyclic heat-stressed finishing broilers

Methyl sulfonyl methane (MSM) is available as a dietary supplement for human and has been associated with multiple health benefits such as reduction of oxidative stress. Heat stress (HS) is an environmental stressor challenging poultry production and known to inflict oxidative stress. We hypothesized that dietary MSM could attenuate HS-induced detrimental effects in broilers mediated by enhancement of antioxidant defenses. Hence, seven hundred ninety-two 1-day-old male Ross 308 broilers were allocated to 3 dietary treatments composed of corn-soybean meal diets with 0 (Ctrl), 1, or 2 g/kg MSM, with 12 replicates (22 birds each) per treatment for 39 d and subjected to a chronic cyclic HS model (temperature of 34°C and 52-58% relative humidity for 6 h daily) from d 24 to 39. MSM at 1 and 2 g/kg linearly increased daily gain and decreased feed-to-gain ratio compared with Ctrl in the grower phase (d 10-21, both P < 0.05). In the finisher phase (d 21-39) none of the performance and carcass indices were affected by treatment (P > 0.05). Nonetheless, data suggest reduced mortality by feeding MSM during HS. Also, during HS the diets with graded levels of MSM resulted in reduced rectal temperatures (P < 0.05) along with linearly decreased panting frequency on d 24 (P < 0.05). MSM supplemented birds showed a trend for linearly decreased thiobarbituric acid reactive substances of breast meat upon simulated retail display (P = 0.078). In addition, MSM administration linearly decreased lipid oxidation in plasma (d 25 and 39, P < 0.05) and breast muscle at d 23 (P < 0.05), concomitantly with linearly increased glutathione levels in erythrocytes (d 23 and 39, P < 0.05; d 25, P < 0.1) and breast muscle (d 23, P < 0.05; d 39, P < 0.1). In conclusion, MSM increased growth performance of broilers during grower phase, and exhibited positive effects on heat tolerance mediated by improved antioxidant capacity in broilers resulting in lower mortality in finisher phase.

Guanidine acetic acid supplementation altered plasma and tissue free amino acid profiles in finishing pigs

Background

As a nutritive feed additive, guanidine acetic acid (GAA) participates in the metabolism of energy and proteins. This study aimed to investigate the effects of GAA on growth performance, organ index, plasma and tissue free amino acid profiles, and related metabolites in finishing pigs. A total of 72 crossbred pigs (body weight 86.59 ± 1.16 kg) were randomly assigned to 1 of 4 dietary treatments (GAA0, GAA500, GAA1000, and GAA1500). They were fed the basal diets supplemented with 0, 500, 1000, or 1500 mg/kg GAA for 42 days, respectively. The growth performance and organ weight were evaluated, and the contents of crude protein, free amino acids, and metabolites in plasma and tissues were determined. Spearman correlation between plasma and tissue free amino acids and related metabolites was also analyzed.

Results

Growth performance in pigs was not altered by GAA (P > 0.05). The absolute and relative weight of kidneys increased (quadratic, P < 0.05). As dietary GAA concentration was increased, the contents of plasma glycine, serine, leucine, ornithine, and ratio of ornithine/arginine decreased (linear or quadratic, P < 0.05), but the contents of plasma isoleucine and taurine and the ratios of alanine/branched-chain amino acids and proline/ornithine increased quadratically (P < 0.05). The hepatic γ-amino-n-butyric acid content increased linearly and quadratically (P < 0.001), while the carnosine content decreased (quadratic, P = 0.004). The contents of renal arginine, proline, cystine, glutamate, and total amino acids (TAA) decreased quadratically (P < 0.05), but the contents of glycine (quadratic, P = 0.015) and γ-amino-n-butyric acid (linear, P = 0.008) increased. The pancreatic tryptophan content (quadratic, P = 0.024) increased, while the contents of pancreatic proline (linear, P = 0.005) and hydroxyproline (quadratic, P = 0.032) decreased in response to GAA supplementation. The contents of cardiac essential amino acids (EAA), nonessential amino acids (NEAA), and TAA in GAA1000 were higher than those in GAA1500 (P < 0.05). Supplementing with GAA linearly increased the contents of methionine, threonine, valine, isoleucine, leucine, phenylalanine, tryptophan, lysine, histidine, arginine, serine, alanine, glutamine, asparagine, tyrosine, proline, taurine, cystathionine, α-aminoadipic acid, β-aminoisobutyric acid, EAA, NEAA, and TAA in the spleen (P < 0.05). A strong Spearman correlation existed between plasma and tissue free amino acids and related metabolites.

Conclusion

GAA supplementation did not altered pig growth performance, but it altered plasma and tissue free amino acid profiles and the contents of related metabolites in pigs in a tissue-dependent manner.

Creatine nitrate supplementation strengthens energy status and delays glycolysis of broiler muscle via inhibition of LKB1/AMPK pathway

This study aimed to evaluate the effects of dietary creatine nitrate (CrN) on growth performance, meat quality, energy status, glycolysis, and related gene expression of liver kinase B1/AMP-activated protein kinase (LKB1/AMPK) pathway in Pectoralis major (PM) muscle of broilers. A total of 240 male Arbor Acres broilers (28-day-old) were randomly allocated to one of 5 dietary treatments: the basal diet (control group), and the basal diets supplemented with 600 mg/kg guanidinoacetic acid (GAA), 300, 600, or 900 mg/kg CrN (identified as GAA₆₀₀, CrN₃₀₀, CrN₆₀₀, or CrN₉₀₀, respectively). We found that dietary GAA and CrN supplementation for 14 d from d 28 to 42 did not affect broiler growth performance, carcass traits, and textural characteristics of breast muscle. GAA₆₀₀, CrN₆₀₀, and CrN₉₀₀ treatments increased pH_24h and decreased drip loss of PM muscle compared with the control (P < 0.05). The PM muscles of CrN₆₀₀ and CrN₉₀₀ groups showed higher glycogen concentration and lower lactic acid concentration accompanied by lower activities of phosphofructokinase (PFK), pyruvate kinase (PK), and lactate dehydrogenase (LDH) (P < 0.05). Simultaneously, GAA₆₀₀ and all CrN treatments increased concentration of muscle creatine, phosphocreatine (PCr) and ATP, and decreased AMP concentration and AMP/ATP ratio (P < 0.05). Meanwhile, the concentrations of muscle creatine, PCr, and ATP were increased linearly, while muscle AMP concentration and AMP/ATP ratio were decreased linearly and quadratic as the dose of CrN increased (P < 0.05). GAA₆₀₀, CrN₆₀₀, and CrN₉₀₀ treatments upregulated mRNA expression of CreaT in PM muscle, and CrN₆₀₀ and CrN₉₀₀ treatments downregulated GAMT expression in liver and PM muscle compared with the control or GAA₆₀₀ groups (P < 0.05). The mRNA expression of muscle LKB1, AMPKα1, and AMPKα2 was downregulated linearly in response to the increasing CrN level (P < 0.05). Overall, CrN showed better efficacy on strengthening muscle energy status and improve meat quality than GAA at the some dose. These results indicate that CrN may be a potential replacement for GAA as a new creatine supplement.

25-hydroxycholecalciferol reverses heat induced alterations in bone quality in finisher broilers associated with effects on intestinal integrity and inflammation

BACKGROUND

Alterations in ambient temperature have been associated with multiple detrimental effects on broilers such as intestinal barrier disruption and dysbiosis resulting in systemic inflammation. Inflammation and 25-hydroxycholecalciferol (25-OH-D₃) have shown to play a negative and positive role, respectively, in the regulation of bone mass. Hence the potential of 25-OH-D₃ in alleviating heat induced bone alterations and its mechanisms was studied.

RESULTS

Heat stress (HS) directly induced a decrease in tibia material properties and bone mass, as demonstrated by lower mineral content, and HS caused a notable increase in intestinal permeability. Treatment with dietary 25-OH-D₃ reversed the HS-induced bone loss and barrier leak. Broilers suffering from HS exhibited dysbiosis and increased expression of inflammatory cytokines in the ileum and bone marrow, as well as increased osteoclast number and activity. The changes were prevented by dietary 25-OH-D₃ administration. Specifically, dietary 25-OH-D₃ addition decreased abundance of B- and T-cells in blood, and the expression of inflammatory cytokines, especially TNF-α, in both the ileum and bone marrow, but did not alter the diversity and population or composition of major bacterial phyla. With regard to bone remodeling, dietary 25-OH-D₃ supplementation was linked to a decrease in serum C-terminal cross-linked telopeptide of type I collagen reflecting bone resorption and a concomitant decrement in osteoclast-specific marker genes expression (e.g. cathepsin K), whereas it did not apparently change serum bone formation markers during HS.

CONCLUSIONS

These data underscore the damage of HS to intestinal integrity and bone health, as well as that dietary 25-OH-D₃ supplementation was identified as a potential therapy for preventing these adverse effects.

L-Citrulline Influences the Body Temperature, Heat Shock Response and Nitric Oxide Regeneration of Broilers Under Thermoneutral and Heat Stress Condition

Heat stress (HS) adversely affects several physiological responses in organisms, but the underlying molecular mechanisms involved are yet to be fully understood. L-Citrulline (L-Cit) is a nutraceutical amino acid that is gaining research interest for its role in body temperature regulation and nitric oxide synthesis. This study investigated whether dietary supplementation with L-Cit (1% of basal diet) could ameliorate the effects of acute HS on thermotolerance, redox balance, and inflammatory responses of broilers. Ross 308 broilers (288 chicks) were subjected to two environments; thermoneutral at 24°C (TNZ) or HS at 35°C for 5 h, and fed two diets; control or L-Cit. The results showed that HS increased the ear, rectal (RT), and core body (CBT) temperatures of broilers, along with higher respiratory rate. The RT and CBT readings were intermittently affected with time effect, whereas, L-Cit supplementation lowered the mean CBT than the control diet. Antioxidant assays showed that superoxide dismutase was increased during HS, while, catalase was promoted by L-Cit supplementation. In addition, L-Cit induced glutathione peroxidase activity compared to the control diet during HS. Hypothalamic heat shock protein (HSP)-90 was upregulated by HS, but L-Cit downregulated heat shock factor (HSF)-1, and HSP 60 mRNA expressions. HSF 3 mRNA expression was downregulated by L-Cit under TNZ condition. More so, HS increased the plasma nitric oxide (NO) concentration but lowered the total NO synthase (tNOS) activity. In contrast, L-Cit supplementation limited NO production but increased the tNOS activity. Arginase activity was increased in the control fed group during HS but L-Cit supplementation lowered this effect. The NOS-COX pathway was significantly affected under TNZ condition, since L-Cit supplementation downregulated the mRNA expression of iNOS-COX2 in the hypothalamus, and further reduced the serum PGE2 concentration. Together, these data indicates that L-Cit influenced the antioxidant defense, heat shock response and nitric oxide regeneration both under thermoneutral and HS conditions; and that L-Cit may be directly and/or indirectly involved in the central regulation of body temperature.

Broiler production challenges in the tropics: A review

Under tropical climate, broiler production is encumbered by several constraints which make it difficult for them to attain their genetic potential. The scarcity and high price of poultry feed and veterinary services and the harsh environmental conditions with respect to thermal stress are some of the challenges that hinder optimal growth of the birds. Limited availability of feedstuffs, including crucial feed ingredients like maize and oil seedcakes, is an important challenge to the sector, since feed still represents a major cost of producing broiler chickens. Additionally, the problem of climate change, which has become a global concern, is the main problem in broiler production under hot and humid climate. Under high ambient temperature, feed intake decreases, carbohydrates metabolism and protein synthesis efficiency are disturbed. Lipid utilization is lower and glucose or insulin homeostasis is altered while fat deposition and oxidative stress increases. Several strategies are used to ameliorate the effect of heat stress in poultry. The objective of this review was to summarize the challenge in broiler production under hot and humid climate and different approaches to fight heat stress in poultry.