Effect of Yeast Fermentate Supplementation on Intestinal Health and Plasma Biochemistry in Heat-Stressed Pekin Ducks

Sex differences in intestinal morphology and increase in diencephalic neuropeptide Y gene expression in female but not male Pekin ducks exposed to chronic heat stress

The impact of heat stress (HS) on production is intricately linked with feed intake. We investigated the effects of HS on intestines and diencephalic genes in Pekin ducks. One hundred and sixty adult ducks were allocated to two treatment rooms. The control room was maintained at 22°C and the HS room at 35°C for the first 10 h of the day then reduced to 29.5°C. After 3 weeks, 10 hens and 5 drakes were euthanized from each room and jejunum and ileum collected for histology. Brains were collected for gene expression analysis using qRT-PCR. Intestinal morphology data were analyzed with two-way ANOVA and diencephalic gene data were analyzed with Kruskal-Wallis test. There was an increase in villi width in the ileum (p = .0136) and jejunum (p = .0019) of HS hens compared to controls. HS drakes showed a higher crypt depth (CD) in the jejunum (p = .0198) compared to controls. There was an increase in crypt goblet cells (GC) count in the ileum (p = .0169) of HS drakes compared to HS hens. There was higher villi GC count (p = .07) in the jejunum of HS drakes compared to controls. There was an increase in the crypt GC density (p = .0054) in the ileum, not jejunum, of HS drakes compared to HS hens. Further, there were no differences in the proopiomelanocortin gene expression in either sex but there was an increase in the expression of neuropeptide Y (NPY) gene in HS hens (p = .031) only and a decrease in the corticotropin releasing hormone gene in the HS drakes (p = .037) compared to controls. These data show that there are sex differences in the effect of HS on gut morphology while the upregulation in NPY gene may suggest a role in mediating response to chronic HS.

Increased abundances of potential pathogenic bacteria and expressions of inflammatory cytokines in the intestine of oyster Crassostrea gigas after high temperature stress

High temperature stress is a significant threat to the health of oysters, but the effects on their intestinal performances are not well understood. In this study, the effects of high temperature stress on the intestinal histology, immune response and associated microbiota were investigated in Crassostrea gigas after rearing at 20, 25 and 28 °C for 21 days. With the increase of temperature, shortened and shed microvilli as well as increased goblet cells were observed in the intestines of oysters. The transcripts of cytokines CgIL17-5, CgTNF-2 and CgTGF-β and apoptosis-related gene CgCaspase-3 in intestine increased with the increasing temperature. Further, the diversity and composition of the oyster intestinal microbiota changed after high temperature stress. The 16S rRNA gene copy number per ng of DNA in the T25 (5.16 × 10⁵) and T28 (1.63 × 10⁵) groups were higher than that in the control group (8.62 × 10⁴). The Chao 1 index in the T25 (238.00) and T28 (240.17) groups was lower than that in the control group (279.00). The Shannon index decreased progressively with the increasing temperature, with the value in the T28 group (4.44) significantly lower than that in the control group (5.40) (p < 0.05). The abundances of potential pathogenic bacteria such as Acinetobacter, Pseudomonas, Vibrio and Endozoicomonas increased while that of probiotic bacteria Bacillus decreased after high temperature exposure. Functional prediction indicated that the pathways associated with bacterial proliferation were enriched at 25 °C, while those involved in protein synthesis were blocked at 28 °C. Collectively, these results suggested that high temperature stress led to an increased abundances of potential pathogenic bacteria and expressions of inflammatory cytokines in the intestine, which may consequently affect the functional integrity of the intestinal barrier in oysters.

Yeast-Derived Products: The Role of Hydrolyzed Yeast and Yeast Culture in Poultry Nutrition—A Review

Simple Summary

Yeast and yeast-derived products are largely employed in animal nutrition to support animals’ health and to improve their performance. Thanks to their components, including mannans, β-glucans, nucleotides, vitamins, and other compounds, yeasts have numerous beneficial effects. Among yeast-derived products, hydrolyzed yeasts and yeast cultures have received less attention, but, although the results are somewhat conflicting, in most of the cases, the available literature shows improved performance and health in poultry. Thus, the aim of this review is to provide an overview of hydrolyzed-yeast and yeast-culture employment in poultry nutrition, exploring their effects on the production performance, immune response, oxidative status, gut health, and nutrient digestibility. A brief description of the main yeast bioactive compounds is also provided.

Abstract

Yeasts are single-cell eukaryotic microorganisms that are largely employed in animal nutrition for their beneficial effects, which are owed to their cellular components and bioactive compounds, among which are mannans, β-glucans, nucleotides, mannan oligosaccharides, and others. While the employment of live yeast cells as probiotics in poultry nutrition has already been largely reviewed, less information is available on yeast-derived products, such as hydrolyzed yeast (HY) and yeast culture (YC). The aim of this review is to provide the reader with an overview of the available body of literature on HY and YC and their effects on poultry. A brief description of the main components of the yeast cell that is considered to be responsible for the beneficial effects on animals’ health is also provided. HY and YC appear to have beneficial effects on the poultry growth and production performance, as well as on the immune response and gut health. Most of the beneficial effects of HY and YC have been attributed to their ability to modulate the gut microbiota, stimulating the growth of beneficial bacteria and reducing pathogen colonization. However, there are still many areas to be investigated to better understand and disentangle the effects and mechanisms of action of HY and YC.

Effects of supplementing yeast fermentate in the feed or drinking water on stress susceptibility, plasma chemistry, cytokine levels, antioxidant status, and stress- and immune-related gene expression of broiler chickens

This study aimed to elucidate the mechanism by which adding Saccharomyces cerevisiae-derived yeast fermentate to the feed (XPC) or drinking water reduces stress in poultry. Day-old male Cobb 500 broiler chicks were assigned to 1 of 3 treatments: stressed control (CS), stressed + XPC (1.25 kg/metric ton feed, day 0-43; XPC), or stressed + AviCare (160 mL/100 L drinking water, day 0-43; AVI). All birds were spray-vaccinated for coccidiosis (day 0), raised on reused litter, spray-vaccinated for Newcastle/Bronchitis (day 18), and exposed to heat stress (32°C-34°C) and feed/water withdrawal for 12 h (day 18). Blood samples were collected to assess plasma corticosterone (CORT) and heterophil/lymphocyte (H/L) ratio (60 birds/treatment; day 40); plasma biochemistry and growth hormone (12 birds/treatment; day 38); and serum serotonin and plasma prolactin, thyroid hormones, antioxidant capacity, and selected cytokines (12 birds/treatment; day 39). Composite asymmetry scores were obtained from 60 birds/treatment on day 41. Organs were collected from 20 birds/treatment on day 43 to measure gene expression of CYP1A2 and melanocortin 2 receptor (MC2R) in the adrenal glands and IL10 and AvBD1 in the spleen. Serotonin was lower in CS than XPC (P = 0.049), whereas AVI was intermediate. Plasma interleukin (IL)-1β was higher in AVI than CS (P = 0.009) and XPC (P = 0.009). The CS treatment had higher CORT than AVI (P = 0.013) and XPC (P = 0.037) and higher H/L ratios than AVI (P = 0.026) and XPC (P = 0.034). Expression of CYP1A2, MC2R, and IL10 was lower (P < 0.05) in XPC and AVI compared with CS. Furthermore, IL10 expression was lower in XPC than AVI (P < 0.05). Adding yeast fermentate to the feed or drinking water reduced measures of stress and MC2R gene expression in birds exposed to acute and rearing stressors. However, differences in IL10 gene expression and circulating serotonin and IL-1β suggest that supplementing yeast fermentate in the feed is slightly more effective than supplementation via the drinking water in mitigating the physiological effects associated with the stress response in broilers.