Effects of alfalfa meal on the intestinal microbial diversity and immunity of growing ducks

Dietary alfalfa hay or lipid-soluble alfalfa extract may improve broiler growth, but fiber presence may be detrimental during Eimeria vaccine challenge

Lipid-soluble components in late-cutting alfalfa are linked to beneficial immune and microbiota responses in mouse challenge models; therefore, responses in a comparative poultry Eimeria challenge model were investigated. The study objective was to evaluate performance, immunity, and the cecal microbiota in broilers fed ground hay or lipid-soluble extract from late (fifth) cutting alfalfa during Eimeria challenge. At hatch, 432 Ross 708 broilers were placed in 24 floor pens (18 birds/pen) and assigned to 3 isocaloric/isonitrogenous dietary treatments consisting of control, 5% ground hay, or 0.25% lipid-soluble extract for a 42-d trial divided into 14 d starter, grower, and finisher periods. On d 14, 4 birds/treatment were euthanized to collect blood and cecal contents before half the remainder were inoculated with 10X Merck Coccivac-B52 (Kenilworth, NJ). Tissue samples were collected at 3, 7, 14, and 28 d postinoculation (pi; 4 birds/diet × Eimeria group) with body weight (BW) and feed intake (FI) recorded weekly. Immune populations within peripheral blood mononuclear cells were characterized by flow cytometry while cecal microbial communities were profiled by 16S rRNA gene amplicon sequencing. Data were normalized when appropriate and analyzed to evaluate the effects of diet, Eimeria challenge, and timepoint (SAS 9.4; P ≤ 0.05). Before challenge, dietary alfalfa hay or extract increased FI 6.9 to 8.0% and increased CD3+ T cells 19.3 to 24.9% compared to control-fed birds (P ≤ 0.007). Alfalfa did not significantly affect post-Eimeria performance, but Eimeria-challenged birds fed hay showed the greatest numeric reduction in final BW compared to their unchallenged counterparts (0.17 kg) vs. control and extract-fed birds (0.02-0.04 kg). Immune cell changes did not indicate recruitment from peripheral blood to local infection sites; however, alfalfa hay may have accelerated Bu-1+ B cell development by 7 d in unchallenged birds (P < 0.0001). During Eimeria-challenge, dietary alfalfa extract preserved alpha diversity measures related to species richness (P ≤ 0.007). Collectively, these results indicate potential benefits of feeding lipid-soluble extract from late cutting alfalfa to broilers during Eimeria challenge.

Investigating the influence of diet diversity on infection outcomes in a bumble bee (Bombus impatiens) and microsporidian (Nosema bombi) host-pathogen system

Diet can have an array of both direct and indirect effects on an organism's health and fitness, which can influence the outcomes of host-pathogen interactions. Land use changes, which could impact diet quantity and quality, have imposed foraging stress on important natural and agricultural pollinators. Diet related stress could exacerbate existing negative impacts of pathogen infection. Accounting for most of its nutritional intake in terms of protein and many micronutrients, pollen can influence bee health through changes in immunity, infection, and various aspects of individual and colony fitness. We investigate how adult pollen consumption, pollen type, and pollen diversity influence bumble bee Bombus impatiens survival and infection outcomes for a microsporidian pathogen Nosema (Vairimorpha) bombi. Experimental pathogen exposures of larvae occurred in microcolonies and newly emerged adult workers were given one of three predominantly monofloral, polyfloral, or no pollen diets. Workers were assessed for size, pollen consumption, infection 8-days following adult-eclosion, survival, and the presence of extracellular microsporidian spores at death. Pollen diet treatment, specifically absence of pollen, and infection independently reduced survival, but we saw no effects of pollen, pollen type, or pollen diet diversity on infection outcomes. The latter suggests infection outcomes were likely already set, prior to differential diets. Although infection outcomes were not altered by pollen diet in our study, it highlights both pathogen infection and pollen availability as important for bumble bee health, and these factors may interact at different stages of bumble bee development, at the colony level, or under different dietary regimes.

Effects of alfalfa saponins on the production performance, serum biochemical factors, and immune factors in Small-Tailed Han sheep

This study aimed to determine the potential effects of alfalfa saponins on the production performance, serum biochemical factors, and immune factors in sheep. Twenty Small-Tailed Han sheep were equally and randomly divided into Groups 1–4, fed with diets containing 0, 5, 10, and 20 g alfalfa saponins per kg, respectively, for 40 consecutive days. During the treatments, the body weight change was recorded for each sheep. Before, during, and after the treatments of alfalfa saponins, serum was collected from each group to compare the levels of biochemical and immune factors. All sheep were killed after the treatments, and the longissimus dorsi muscle was collected to compare the meat quality. The results validated the effects of alfalfa saponins on the growth performance and meat quality in Small-Tailed Han sheep, and the supplementation level of 10 g/kg was the best. Alfalfa saponins also had effects on the levels of biochemical factors in serum. However, both dose- and time-dependent effects were observed. After a shorter feeding period (14 days), the concentrations of cholesterol (CHOL) and low-density lipoprotein (LDL) in Groups 2, 3, and 4 were all lower than those in the control group; however, when alfalfa saponins were continuously fed, this effect was not apparent or even gone. Supplying alfalfa saponins increased serum concentrations of IgA, IgG, IgE, IgM, IL-1, IFN-α, and IFN-β. And this effect was distinctly observed in Groups 3 and 4. Based on the current results, the alfalfa saponins concentration of 10 g/kg (for 14 consecutive days) could be suggested as the optimum ratio for good health conditions of Small-Tailed Han sheep.

Effects of supplementing sow diets during late gestation with Pennisetum purpureum on antioxidant indices, immune parameters and faecal microbiota

The purpose of this study was to investigate the effects of adding Pennisetum purpureum (P. purpureum, also known as Napier grass or elephant grass) to the diets of late gestation on the antioxidant indexes, immune indexes and faecal microbiota of sows. At the 90 days of gestation, 300 healthy sows were randomly divided into three groups, and they received the basic commercial diet or added 5% P. purpureum and 10% P. purpureum, respectively. The experiment started from 90 days of gestation to parturition. The results showed that the total antioxidant capacity, immunoglobulins and serum equol concentrations of sows on 100 days of gestation and at parturition increased linearly (p < .05) with the increase of the content of P. purpureum in the gestation diet. The 5% P. purpureum increased the relative abundance of Bacteroidetes (p = .027) and Actinobacteria (p < .001) at phylum level, Coriobacteriaceae (p < .001) at family level and Prevotellaceae_UCG_001 (p = .004) at genus level, and decreased the relative abundance of Escherichia_Shigella (p < .001) at genus level. In summary, this study shows that the additive of P. purpureum can increase the concentration of serum equol, improve the antioxidant capacity and immune function of sow in late gestation. In addition, the additive of 5% P. purpureum in the diet might change the composition of intestinal microbiota of sows, particularly the relative abundance of Coriobacteriaceae (p < .001) increased.

Effects of grazing mixed-grass pastures on growth performance, immune responses, and intestinal microbiota in free-range Beijing-you chickens

There is an increasing interest in free-range poultry with the increasing focus on food safety and animal welfare. This study was conducted to evaluate the effects of grazing mixed-grass pastures on growth performance, immune responses, and intestinal microbiota in free-range laying chickens. Ten-week-old female Beijing-you chickens were blocked by the BW and randomly assigned to 3 free-range systems in poplar plantations for 120 d: forage-removed paddocks with a high stocking density of 5 m²/hen (control [CK]); mixed-grass pastures with a low stocking density of 6 m²/hen ;or mixed-grass pastures with a high stocking density of 5 m²/hen. Intestinal microbial community analysis was performed by 16S rRNA gene sequencing using Illumina MiSeq. The results revealed that no differences (P > 0.05) were found between the 3 raising systems for the BW and ADG. Chickens grazing mixed-grass pastures exhibited decreased (P > 0.05) mortality and improved immune responses as evidenced by increased T-lymphocyte proliferation (P > 0.05) and immunoglobulin A (P > 0.05) and immunoglobulin M concentrations (P < 0.05) compared with those raised in forage-removed paddocks. Metagenomic analysis indicated that grazing mixed-grass pastures regulated the intestinal microbiota by increasing the prevalence of beneficial bacteria, such as Lactobacillus, Bacteroides, and Faecalibacterium, and reducing potentially pathogenic bacteria population, such as the Rikenellaceae_RC9_gut_group compared with the CK. Therefore, this study indicated that grazing mixed-grass pastures could positively influence intestinal microbiota that may contribute to the overall growth and immunity of free-range chickens and that a low stocking density of 6 m²/hen was optimal to Beijing-you chickens grazing mixed-grass pastures.

Host immunity and the colon microbiota of mice infected with Citrobacter rodentium are beneficially modulated by lipid-soluble extract from late-cutting alfalfa in the early stages of infection

Alfalfa is a forage legume commonly associated with ruminant livestock production that may be a potential source of health-promoting phytochemicals. Anecdotal evidence from producers suggests that later cuttings of alfalfa may be more beneficial to non-ruminants; however, published literature varies greatly in measured outcomes, supplement form, and cutting. The objective of this study was to measure body weight, average daily feed intake, host immunity, and the colon microbiota composition in mice fed hay, aqueous, and chloroform extracts of early (1^st) and late (5^th) cutting alfalfa before and after challenge with Citrobacter rodentium. Prior to inoculation, alfalfa supplementation did not have a significant impact on body weight or feed intake, but 5^th cutting alfalfa was shown to improve body weight at 5- and 6-days post-infection compared to 1^st cutting alfalfa (P = 0.02 and 0.01). Combined with the observation that both chloroform extracts improved mouse body weight compared to control diets in later stages of C. rodentium infection led to detailed analyses of the immune system and colon microbiota in mice fed 1^st and 5^th cutting chloroform extracts. Immediately following inoculation, 5^th cutting chloroform extracts significantly reduced the relative abundance of C. rodentium (P = 0.02) and did not display the early lymphocyte recruitment observed in 1^st cutting extract. In later timepoints, both chloroform extracts maintained lower splenic B-cell and macrophage populations while increasing the relative abundance of potentially beneficially genera such as Turicibacter (P = 0.02). At 21dpi, only 5^th cutting chloroform extracts increased the relative abundance of beneficial Akkermansia compared to the control diet (P = 0.02). These results suggest that lipid soluble compounds enriched in late-cutting alfalfa modulate pathogen colonization and early immune responses to Citrobacter rodentium, contributing to protective effects on body weight.

Associations of Gut Microbiota With Heat Stress-Induced Changes of Growth, Fat Deposition, Intestinal Morphology, and Antioxidant Capacity in Ducks

Accumulating evidence has revealed the dysbiosis of gut/fecal microbiota induced by heat stress (HS) in mammals and poultry. However, the effects of HS on microbiota communities in different intestinal segments of Cherry-Valley ducks (a widely used meat-type breed) and their potential associations with growth performances, fat deposition, intestinal morphology, and antioxidant capacity have not been well evaluated yet. In this study, room temperature (RT) of 25°C was considered as control, and RT at 32°C for 8 h per day was set as the HS treatment. After 3 weeks, the intestinal contents of jejunum, ileum, and cecum were harvested to investigate the microbiota composition variations by 16S ribosomal RNA amplicon sequencing. And the weight gain, adipose indices, intestinal morphology, and a certain number of serum biochemical parameters were also measured and analyzed. The results showed the microbial species at different levels differentially enriched in duck jejunum and cecum under HS, while no significant data were observed in ileum. HS also caused the intestinal morphological changes (villus height and the ratio of villus height to crypt depth) and the reductions of growth speed (daily gain), levels of serum triglyceride (TG) and total cholesterol, and antioxidant activity (higher malondialdehyde (MDA) content and lower total antioxidant). The higher abdominal fat content and serum glucose level were also observed in HS ducks. The Spearman correlation analysis indicated that in jejunum the phyla Firmicutes and Proteobacteria were associated with average daily gain, feed/gain, serum TG and MDA levels, and villus height/crypt depth (P < 0.05). The phylum Firmicutes and genus Acinetobacter were significantly associated with fat deposition and serum glucose level (P < 0.05). The genus Lactobacillus was positively associated with serum total antioxidant (P < 0.05), while some other microbial species were found negatively associated, including order Pseudomonadales, genera Acinetobacter, and unidentified_Mitochondria. However, no significant correlations were observed in cecum. These findings imply the potential roles of duck gut microbiota in the intestinal injuries, fat deposition, and reductions of growth speed and antioxidant capacity caused by HS, although the molecular mechanisms requires further investigation.

Effect of Varying Proportions of Lignin and Cellulose Supplements on Immune Function and Lymphoid Organs of Layer Poultry (Gallus gallus)

To determine the benefits of different types or proportions of insoluble fiber components on growth and immunity, 4-week-old commercial layer pullets were fed supplements containing different proportions of purified lignin and cellulose or a commercial lignocellulose supplement. The 64 Hy-Line Brown pullets were provided basal diets supplemented with 1 g fiber per 100 g diet. The supplements included a commercial lignocellulose, Arbocel® RC fine (group A) with cellulose to lignin ratio of approximately 3:1, cellulose (group Ce), a 3:1 mixture of cellulose: lignin (group Ce3Lig1), and a 2:1 mixture of cellulose: lignin (group Ce2Lig1). After 3 weeks, innate immune function was measured in terms of heterophil phagocytosis and oxidative burst (n=8). After 4 weeks, ex vivo stimulated lymphocyte proliferation was determined for assessment of cell-mediated immune function (n=7). All pullets were killed at 9 weeks of age and lymphoid organs were weighed (n=16) and small intestinal Peyer's patches (PP) were measured (n=8). Pullets in both A and Ce3Lig1 groups had heavier (P<0.05) body and bursa of Fabricius weights. The number of PP in group A was higher (P<0.05) than in group Ce. The percentage of heterophil phagocytosis in A and Ce3Lig1 groups were higher (P<0.05) than in group Ce, and oxidative burst of group A was higher (P<0.05) than that of group Ce. Addition of 1% Arbocel or 1% Ce3Lig1 to the diet of layer pullets from 4 to 9 weeks of age significantly improved their growth and innate immune function compared to group Ce. This suggests that lignin either modulates the effect of cellulose or has specific mechanisms of action in the gut that improves growth and immunity. The proportion of lignin to cellulose may also be important for growth and immune function.

Supplementing the feeds of layer pullets, at different ages with two different fiber sources improves immune function

Two experiments were conducted to study the effects of lignocellulose supplementation on immune function in layer pullets at different stages of growth. Four-wk-old pullets (Experiment 1) were fed a control, diet (Diet C); Diet C plus 1% mixed soluble/insoluble fiber (Diet MF), or plus 1% insoluble fiber (Diet IF). At 7.5 wk-of-age, heterophil phagocytosis, and oxidative burst in Groups MF (328.5 beads/100 cells; 4,330.0 ΔRFU; relative fluorescent units) and IF (350.3; 5,264.4) were greater (P < 0.05) than Controls (303.4; 3,509.0). At 8 wk-of-age, Group MF and IF relative weights of bursa of Fabricius (0.57 g/100 g BW; 0.58 g /100 g BW), thymus glands (0.77; 0.78), and areas of Peyer's patches (PP) (2.7 cm2; 2.9 cm2) were higher (P < 0.05) than Controls (bursa, 0.50 g; thymus, 0.70 g; PP area, 1.8 cm2). In Experiment 2, 10-wk-old pullets were fed a control diet or diets containing 1.5% MF or IF for 8 wk. At 14 wk-of-age IF pullets had higher (P < 0.05) heterophil phagocytosis efficiency (447.9 beads/100 cells) than Controls (376.4) and MF and IF had greater (P < 0.05) oxidative burst (1,302.9 and 1,857.7 ΔRFU) than Controls (744.1). At 17 wk-of-age MF and IF had increased (P < 0.05) proliferation of T-lymphocytes (ConcanavalinA-stimulated) (100.4 and 103.1% of unstimulated cells) and B-lymphocytes (lipopolysaccharide-stimulated) (122.4 and 129.0) than Controls (ConA, 79.4; lipopolysaccharide, 106.6). At 18 wk-of-age, IF pullets were heavier (1,607.5 g, P < 0.05) than Controls (1,506.5 g), had heavier (P < 0.05) bursa of Fabricius (1.12 g) than MF and Control groups (0.98 g; 0.92 g) and cecal tonsils of MF (0.38 g) and IF (0.39 g) weighted more (P < 0.05) than Controls (0.33 g). Number of jejunal and ileal PP (10.0) in IF pullets was higher (P < 0.05) than Controls (7.1). These results indicate that both MF and IF can improve development of the immune system of young and grower pullets during periods of maturation and involution of lymphoid organs.