Effects of Short- and Medium-Chain Fatty Acids on Production, Meat Quality, and Microbial Attributes-A Review

The non-therapeutic use of antimicrobials in poultry production contributes to the spread of drug-resistant pathogens in both birds and humans. Antibiotics are known to enhance feed efficiency and promote the growth and weight gain of poultry. New regulatory requirements and consumer preferences have led to a reduced use of antibiotics in poultry production and to the discovery of natural alternatives to antibiotic growth promoters. This interest is not only focused on the direct removal or inhibition of causative microorganisms but also on the prevention of diseases caused by enteric pathogens using a range of feed additives. A group of promising feed additives is composed of short- and medium-chain fatty acids (SCFAs and MCFAs) and their derivatives. MCFAs possess antibacterial, anticoccidial, and antiviral effects. In addition, it has been proven that these acids act in synergy if they are used together with organic acids, essential oils, or probiotics. These fatty acids also benefit intestinal health integrity and homeostasis in broilers. Other effects have been documented as well, such as an increase in intestinal angiogenesis and the gene expression of tight junctions. The aim of this review is to provide an overview of SCFAs and MCFAs as alternatives to antibiotic growth promoters and to summarize the current findings in the literature to show their possible benefits on production, meat quality, and gut health in poultry.

Evaluation of Liquid Organic Acids on the Performance, Chyme pH, Nutrient Utilization, and Gut Microbiota in Broilers under High Stocking Density

This study aimed to evaluate the efficacy of organic acids (OAs) in starter broilers and to investigate whether supplemental OAs could alleviate the high stocking density (HSD) stress condition in grower broilers. A total of 408 1-day-old Arbor Acres broilers were assigned into two groups without or with liquid OAs in the starter phase. In the grower phase, each group in the starter phase was divided into a normal stocking density and an HSD. The OA dose was 0.16% at the starter and grower phases. The results showed that at the starter phase, OAs decreased the chyme pH in gizzard and duodenum and increased the activities of chymotrypsin and α-amylase in the duodenal chyme (p < 0.05). In the grower phase, an HSD decreased the growth performance and the ether extract digestibility (p < 0.01). The supplementation of OAs decreased the chyme pH in the gizzard, proventriculus, and duodenum and increased the lipase and α-amylase activities (p < 0.05). The supplemental OAs increased the dry matter and total phosphorous digestibility and the contents of acetic acids, butyric acids, isovaleric acids, and valeric acids (p < 0.05). For cecal microbial compositions at the genus level, an HSD decreased the relative abundance of Blautia, Norank_f__norank_o__RF39, and Alistipes, while supplemental OAs increased the relative abundance of Norank_f__norank_o__RF39 (p < 0.05). In conclusion, although there were no interaction effects between OAs and stocking densities in the present study, it was clear that the supplementation of OAs has beneficial effects on the chyme pH, enzymes activities, and nutrient digestibility in broilers, while an HSD existed adverse effects on the growth performance, nutrient digestibility, and gut microbiota balance in grower broilers.

The Effects of Different Forms of Butyric Acid on the Performance of Turkeys, Carcass Quality, Incidence of Footpad Dermatitis and Economic Efficiency

Simple Summary

Butyric acid is a short-chain organic acid with established antimicrobial properties. It decreases the pH of intestinal digesta and reduces the abundance of pathogenic bacteria, thus indirectly improving the growth performance of birds. In the present study, turkey diets were supplemented with different forms of butyric acid. The efficiency of bird production and carcass dressing percentage were improved when butyric acid glycerides or coated sodium butyrate were added to the diet. An improvement in footpad condition and an increase in the dry matter content of faeces were noted in birds fed experimental diets. The addition of butyric acid in various forms to turkey diets improved the economic efficiency of production. The results of this study suggest that different forms of butyric acid improve production efficiency, carcass traits, and footpad condition in turkeys. Therefore, sodium butyrate, coated sodium butyrate, and butyric acid glycerides can be valuable feed additives in turkey nutrition.

Abstract

The aim of this study was to compare the efficacy of butyric acid glycerides (BAG), sodium butyrate (SB) and coated sodium butyrate (CSB) in turkey nutrition based on the growth performance of birds, carcass yield, meat quality, the dry matter (DM) content of faeces, the incidence of footpad dermatitis (FPD), and economic efficiency. A 105-day experiment was conducted on 400 BIG 6 female turkeys (4 treatments, 5 replications, 20 birds per replication). The addition of CSB and BAG to turkey diets improved the feed conversion ratio (FCR, p ≤ 0.05) and increased the values of the European Efficiency Index (EEI, p ≤ 0.01). The analysed forms of BA in turkey diets increased the concentration of DM in faeces (p ≤ 0.01) and decreased FPD incidence (p ≤ 0.01), which may suggest that all forms of butyrate improved litter quality and inhibit the risk for diarrhoea. The results of this study indicate that all forms of butyric acid can be valuable feed additives in turkey nutrition.

Dietary strategies to alleviate high-stocking-density-induced stress in broiler chickens – a comprehensive review

Stocking broilers at a high density has been a strategy to optimize the area of the cage and hence increase the efficiency of broiler production. If the environmental (microclimate) conditions and rearing management are not properly managed, stocking broilers at a high density may, however, result in stressful conditions that are harmful for the production, health and welfare of broilers. To ameliorate these unfavorable effects of overcrowding stress, dietary interventions have been conducted. Probiotics, prebiotics, synbiotics, plant-derived products, vitamins, propolis, amino acids, fatty acids, etc. have been supplemented in diets to deal with the harmful impact of stress induced by a high stocking density of broilers. This review covers the detrimental effects of overcrowding-induced stress on broiler development and attempts to ameliorate those negative effects by dietary interventions.

Effect of Dietary Inclusion of Alpha-Monolaurin on the Growth Performance, Lipid Peroxidation, and Immunity Response in Broilers

As the world population increases, there will be an increase in demand for poultry meat. To satisfy this requirement, sustainably will be a significant challenge as different countries in the world face different health problems. Additionally, for decades, poultry nutritionists have worked on sustainability in broiler manufacturing plants. The usage of short- and medium-chain fatty acids (MCFAs), which have positive effects as growth promoters and immunostimulants, is a pioneering way to decrease the cost of diets and improve environmentally friendly and sustainable production in this critical era. This study aimed at evaluating the influences of alpha-monoglyceride (alpha-monolaurin) on the growth performance, biochemical parameters, lipid profiles, liver oxidative stress, and immune response in broilers. Alpha-monolaurin was included at the levels of 0 (control), 0.25, 0.5, and 1 g/kg in broiler diets. After 33 days, dietary supplementation of alpha-monolaurin showed no impact on the feed intake; however, broilers fed 0.5 g/kg feed displayed a significantly reduced food conversion ratio, as compared to the control (p ≤ 0.05). However, body weight and body weight gain tended to increase after 0.25 g/kg alpha-monolaurin supplementation, as compared to other groups. The highest European production efficiency factor (EPEF) was obtained with 0.25 g/kg alpha-monolaurin supplementation. The ether extract utilization and spleen weight were improved substantially (p ≤ 0.05) by alpha-monolaurin supplementation, but muscle and other organ weights were not affected. Plasma alanine transaminase (ALT) was decreased significantly by alpha-monolaurin supplementation, while plasma total protein and albumin were enhanced (p ≤ 0.05). Interestingly, broilers fed alpha-monolaurin displayed an increased antibody titer of the Newcastle disease (ND) virus and muscle unsaturated fatty acid content, and a decreased liver content of malondialdehyde (MDA). It could be assumed that dietary supplementation of alpha-monolaurin positively impacts birds’ feed efficiency and immune response and can be applied as a natural immune enhancer in the broiler industry.

Dietary medium-chain α-monoglycerides increase BW, feed intake, and carcass yield in broilers with muscle composition alteration

Glycerol monolaurate (GML), a member of medium-chain α-monoglycerides (MG), is proved to be beneficial for productive performance, feed efficiency, and health of broilers based on recent research. The present study aims to evaluate the effect of MG mixture rich in GML and glycerol monodecanoate on performance, intestinal development, serum parameters, carcass yield, and muscle composition in broilers. A total of 528 chicks were weighed and randomly assigned into 4 groups (22 chicks/replicate, 6 replicates/group) for a 56-d experiment. The control group received a basal diet containing 0 mg/kg MG (CON), and the treated groups fed basal diets containing 300 (MG300), 450 and 600 mg/kg MG. The results revealed that the BW (P < 0.05), ADG, and ADFI were notably increased in MG-containing groups during the finisher phase compared with the CON group. Remarkable intestinal improvements were observed in the duodenum and jejunum of MG-treated groups, but no statistical differences were obtained. Dietary MG significantly (P < 0.05) increased the serum high-density lipoprotein cholesterol, total protein, and superoxide dismutase content in broilers. Inclusion of 300 mg/kg MG in diet increased the eviscerated yield (P = 0.066), leg muscle (P < 0.01) and breast muscle yield (P = 0.083), and improved the fresh meat quality with reduced drip loss (P < 0.01) and pH decline (P < 0.01) compared with the CON group. Moreover, the saturated fatty acid (P = 0.073), flavor amino acid (P < 0.05), and total amino acid (P < 0.05) content was notably higher in the muscle of the MG300 group than that in the CON group. In summary, these findings revealed that mixed MG can be used as an effective and novel feed supplement to improve productive performance and quality of broilers.

Effect of Dietary Medium-Chain α-Monoglycerides on the Growth Performance, Intestinal Histomorphology, Amino Acid Digestibility, and Broiler Chickens' Blood Biochemical Parameters

Simple Summary

The addition of biologically active materials to animal feed is a very recent topic regarding antibiotic alternatives. This study inspected the influence of graded levels of medium-chain α-monoglycerides, glycerol monolaurate (GML) on the growth performance, apparent ileal digestibility coefficient (AID%) of amino acids, and intestinal histomorphology of broiler chickens. Broiler chickens (76.82 g ± 0.40, n = 200) were fed on four experimental diets that were complemented with 0; 1; 3; or 5 g kg⁻¹ glycerol monolaurate (GML0; GML1; GML3; and GML5). The findings suggested that glycerol monolaurate supplementation can improve the immune status and intestinal histomorphology of broiler chickens with no improving effect on the growth performance.

Abstract

This trial was conducted to assess the impact of medium-chain α-monoglycerides, glycerol monolaurate (GML) supplementation on the growth performance, apparent ileal digestibility coefficient (AID%) of amino acids, intestinal histomorphology, and blood biochemical parameters of broiler chickens. Three-day-old chicks (76.82 g ± 0.40, n = 200) were haphazardly allocated to four experimental groups with five replicates for each (10 chicks/replicate). The treatments consisted of basal diets supplemented with four glycerol monolaurate levels; 0, 1, 3, or 5 g kg⁻¹ (GML0, GML1, GML3, and GML5, respectively). Growth performance was determined at three periods (starter, grower, and finisher). Dietary GML had no significant effect on the growth performance parameters (body weight, weight gain, and feed conversion ratio) through all the experimental periods. GML1 diet increased the AID% of leucine and decreased the AID% of arginine. GML1 diet increased the duodenal and jejunal villous height and the jejunal muscle thickness. GML3 and GML5 diets increased the goblet cell count in the duodenum. GML supplementation increased the serum level of high density lipoprotein (HDL)-cholesterol. GML5 diet increased the serum levels of IgM and interleukin 10 compared to the control group. We could conclude that dietary supplementation of glycerol monolaurate can supplement broiler chicken diets up to 5 g kg⁻¹ to enhance the immune status and intestinal histomorphology of birds with no improving effect on growth performance.

Effects and interaction of dietary electrolyte balance and citric acid on the intestinal function of weaned piglets

Fifty-six piglets (6.26 ± 0.64 kg BW) were weaned at 21 d and randomly assigned to one of the eight dietary treatments with seven replicate pens for a 14-d experimental period. The eight experimental diets were prepared via a 2 × 4 factorial arrangement with citric acid (CA; 0% and 0.3%) and dietary electrolyte balance (dEB, Na + K - Cl mEq/kg of the diet; -50, 100, 250, and 400 mEq/kg). Varying dEB values were obtained by altering the contents of calcium chloride and sodium bicarbonate. An interaction (P < 0.05) between dEB and CA in diarrhea score and the number of goblet cell in jejunum were observed. Ileum pH significantly decreased in weaned piglets fed 250 mEq/kg dEB diet compared with those fed -50 and 400 mEq/kg dEB diets (P < 0.05). Supplementation of 0.3% CA decreased the number of goblet cell in the ileal crypt (P < 0.05) and the relative mRNA expression of cystic fibrosis transmembrane conductance regulator, tumor necrosis factor-α, interferon-γ (IFN-γ), interleukin-1β (IL-1β), interleukin-10 (IL-10), zona occludens-1, and Claudin-1 (P < 0.05). Increasing dEB values increased the number of goblet cells in the jejunal crypt (P < 0.05). A 250-mEq/kg dEB diet decreased the relative mRNA expression of IFN-γ, IL-1β, and IL-10 (P < 0.05) than 100-mEq/kg dEB diet. The interaction between dEB and CA on the relative abundances of Cyanobacteria and Saccharibacteria was observed (P < 0.05). Supplementation of 0.3% CA increased relative abundances of and Streptococcus hyointestinalis. Piglets fed 250-mEq/kg diet increased relative abundances of Firmicutes and Lactobacillus rennini, and decreased the relative abundance of Proteobacteria, Veillonella, Actinobacillus minor, and Escherichia-Shigella.In conclusion, supplementation of 0.3% CA resulted in differential expression of inflammatory cytokines, ion transporters, and tight junction proteins, and changes in the microbial community composition. A 250-mEq/kg dEB diet reduced gastrointestinal pH and promoted the enrichment of beneficial microbes in the gut microbiota, thereby suppressing inflammation and harmful bacteria. However, the addition of CA to diets with different dEB values did not promote intestinal function in weaned piglets.

Valeric acid glyceride esters in feed promote broiler performance and reduce the incidence of necrotic enteritis

Valeric acid is a C5 fatty acid, naturally produced in low concentrations by specific members of the microbiota of the lower intestinal tract. Effects of valeric acid on intestinal health have been poorly investigated. Valeric acid derivatives can be produced as glyceride esters and added to broiler feed. In the current study, experiments were carried out to evaluate the effect of valeric acid glycerides (GVA) on growth performance, on the morphology of the small intestinal mucosa and on protection against necrotic enteritis. In a first feeding trial, Ross-308 chicks were randomly divided into 2 dietary treatment groups and fed either a non-supplemented diet or a diet supplemented with GVA (1.5 g/kg). In the GVA supplemented group, the feed conversion ratio was significantly decreased during the entire trial period (D1-37). In a second trial, gut wall morphology was evaluated. In broilers fed a GVA-containing diet at 5 g/kg, the villus height/crypt depth ratio in the jejunum was significantly increased (P ≤ 0.05), and the crypt depth was significantly decreased at 28 d. In a third trial, immunohistochemistry showed that the density of glucagon-like peptide-2 immunoreactive cells in jejunal and ileal villi from broilers supplemented with GVA (5 g/kg) was significantly increased (P ≤ 0.05) on d 10. In a necrotic enteritis challenge model, a significant reduction of the number of birds with necrotic lesions was found at d 21, using in-feed supplementation of low and high regimen of GVA. These data show that GVA supplementation to broiler feed can decrease the feed conversion, positively affect the morphology of the small intestinal mucosa, increase the density of glucagon-like peptide-2 producing enteroendocrine cells, and reduce the incidence of necrotic enteritis, making GVA a valuable candidate feed additive for broilers.