The objective of this study was to investigate the effects of dietary
Bacillus subtilis
supplementation on growth performance, jejunal lesion scores, oocyst shedding, and cytokine and tight junction protein expression in broiler chickens infected with
Eimeria maxima
. A total of 196 male day-old Ross 708 broilers were given a nonexperimental diet until 14 D of age. Then, all chickens were randomly assigned to one of seven dietary treatments: 2 basal diets (
CON
and
NC
); CON + virginiamycin (
AB1
); CON + bacitracin methylene disalicylate (
BMD
;
AB2
); CON +
B. subtilis
1781 (
PB1
); CON +
B. subtilis
747 (
PB2
); or CON +
B. subtilis
1781 + 747 (
PB3
). At day 21, all chickens except those in the CON group were orally inoculated with
E. maxima
oocysts. At 7 D after
E. maxima
infection, the body weight gains of chickens fed PB2 and PB3 increased (
P
= 0.032) as much as those in chickens fed AB2. The body weight gain and feed efficiency of chickens fed PB2 were significantly increased (
P
< 0.001), and PB2 chickens showed (
P
= 0.005) the lowest lesion scores after
E. maxima
infection. Chickens fed PB2 showed (
P
< 0.05) lower mRNA expression of IL-1β in infected chicken groups. Chickens in the AB1, AB2, PB1, PB2, and PB3 groups showed (
P
< 0.05) greater mRNA expression of junctional adhesion molecule 2 in jejunal tissue, whereas occludin expression increased (
P
< 0.05) in the jejunal tissue of chickens fed AB2 or PB2. Dietary
B. subtilis
supplementation significantly improved the growth performance of young chickens to a level comparable with that induced by virginiamycin or BMD without
E. maxima
infection. After infection with
E. maxima
, dietary virginiamycin and BMD significantly enhanced the epithelial barrier integrity, and the dietary
B. subtilis
747 showed significantly enhanced growth performance, intestinal immunity, and epithelial barrier integrity. Together our results indicated that certain strains of
B. subtilis
provide beneficial effects on the growth of young broiler chickens and have the potential to replace antibiotic growth promoters.
The purpose of this study was to examine the effects of alpha-linolenic acid (ALA) treatment during in vitro maturation (IVM) on nuclear maturation, intraoocyte glutathione (GSH) content, meiotic progression, and developmental competence after parthenogenesis (PA) and somatic cell nuclear transfer (SCNT) in pigs. Medium-199 containing 10% (vol/vol) porcine follicular fluid (PFF; PPF control) or 0.4% (wt/vol) fatty acid-free BSA (BSA control) was used for IVM. The proportion of oocytes reaching the metaphase II (MII) stage was not influenced by ALA treatment at various concentrations (50, 100, and 200 μ). However, treatment with 100 μ ALA significantly increased ( < 0.05) intraoocyte GSH content (1.19 vs. 1.00 and 0.92 pixels per oocyte, comparing the treated oocytes, BSA control, and PFF control, respectively) and embryonic development to the blastocyst stage after PA (47.1 vs. 35.5 and 35.2%) and SCNT (31.4 vs. 23.9 and 24.3%). ALA treatment (100 μ) accelerated oocyte maturation, and a higher proportion of ALA-treated oocytes (89.6%) reached the MII stage than did the untreated controls (75.5%) at 33 h of IVM. Mitogen-activated protein kinase kinase inhibitor (U0126) treatment during IVM inhibited nuclear maturation and embryonic development after PA. However, 100 μ ALA completely counteracted the suppressive effect of U0126 on nuclear maturation and partially counteracted the effect on blastocyst formation. Our results demonstrate that treatment with 100 μ ALA during IVM improves developmental competence by accelerating nuclear maturation and also influencing cytoplasmic maturation, such as increased GSH content in IVM oocytes.
“Gut health” refers to the physical state and physiological function of the gastrointestinal tract and in the livestock system; this topic is often focused on the complex interacting components of the intestinal system that influence animal growth performance and host-microbial homeostasis. Regardless, there is an increasing need to better understand the complexity of the intestinal system and the various factors that influence gut health, since the intestine is the largest immune and neuroendocrine organ that interacts with the most complex microbiome population. As we face the post-antibiotic growth promoters (AGP) era in many countries of the world, livestock need more options to deal with food security, food safety, and antibiotic resilience to maintain agricultural sustainability to feed the increasing human population. Furthermore, developing novel antibiotic alternative strategies needs a comprehensive understanding of how this complex system maintains homeostasis as we face unpredictable changes in external factors like antibiotic-resistant microbes, farming practices, climate changes, and consumers’ preferences for food. In this review, we attempt to assemble and summarize all the relevant information on chicken gut health to provide deeper insights into various aspects of gut health. Due to the broad and complex nature of the concept of “gut health”, we have highlighted the most pertinent factors related to the field performance of broiler chickens.
Chicken NK-lysin peptide 2 (cNK-2) is a natural lytic peptide with direct cytotoxicity against many apicomplexan parasites including Eimeria. Developing an effective oral delivery strategy to express cNK-2 in the intestine, where Eimeria parasites interact with the host's gut epithelial cells, may effectively reduce the fecundity of parasites and minimize intestinal damage. Furthermore, cNK-2 modulates gut immune responses to decrease local inflammation elicited by Eimeria infection in the intestine. Therefore, we developed a stable strain of Bacillus subtilis (B. subtilis) that carries cNK-2 to the gut to determine its effectiveness in ameliorating the negative impacts of coccidiosis and to replace the use of antibiotics in controlling coccidiosis in commercial broiler chicken production. Chickens were randomly allocated into eight treatment groups: two control groups (NC: E. acervulina infected non-B. subtilis control; CON: non-infected control); three B. subtilis-empty vector (EV) groups (EV6: 106 cfu/day/bird; EV8: 108 cfu/day/bird; EV10: 1010 cfu/day/bird), and three B. subtilis-cNK-2 groups (NK6: 106 cfu/day/bird; NK8: 108 cfu/day/bird; NK10: 1010 cfu/day/bird). All chickens, except those in the CON group, were challenged with 5,000 freshly sporulated E. acervulina oocysts through oral gavage on day 15. Chickens were given an oral dose of B. subtilis on days 14, 15, and 16. Body weight, weight gains, and fecal oocyst shedding were measured. To investigate the efficacy of oral B. subtilis-cNK-2 against coccidiosis, gene expression of gut health-related biomarkers was measured using RT-PCR. Markers included SOD1, CAT, and HMOX1 for oxidative stress in the spleen and intestinal mucosa, OCLN, ZO-1, and JAM2 for tight junction proteins, and MUC2 for mucin gene expression in the gut. The results showed that oral treatment of young chickens with B. subtilis-cNK-2 improved growth performance, enhanced gut integrity, and reduced fecal oocyst shedding. Altogether, these results confirm B. subtilis-cNK-2 treatment as a promising and effective alternative strategy to replace antibiotics against coccidiosis based on its ability to reduce parasite survival, to reduce coccidiosis-induced body weight loss, and to decrease gut damage based on the enhanced expression of proteins associated with gut integrity and intestinal health.
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