A. Ijaz

Effect of supplementation of prebiotic mannan-oligosaccharides and probiotic mixture on growth performance of broilers subjected to chronic heat stress

The present study was aimed at elucidating the effects of supplementing mannan-oligosaccharides (MOS) and probiotic mixture (PM) on growth performance, intestinal histology, and corticosterone concentrations in broilers kept under chronic heat stress (HS). Four hundred fifty 1-d-old chicks were divided into 5 treatment groups and fed a corn-soybean diet ad-libitum. The temperature control (CONT) group was held at the normal ambient temperature. Heat stress broilers were held at 35 ± 2°C from d 1 until the termination of the study at d 42. Heat stress groups consisted of HS-CONT fed the basal diet; HS-MOS fed the basal diet containing 0.5% MOS; HS-PM fed the basal diet containing 0.1% PM; and HS-SYN (synbiotic) fed 0.5% MOS and 0.1% PM in the basal diet. Broilers were examined at d 21 and 42 for BW gain, feed consumption, feed conversion ratio (FCR), serum corticosterone concentrations, and ileal microarchitecture. The results revealed that the CONT group had higher (P < 0.01) feed consumption, BW gain, and lower FCR on d 21 and 42, compared with the HS-CONT group. Among supplemented groups, the HS-MOS had higher (P < 0.05) BW gain and lower FCR compared with the HS-CONT group. On d 21 and 42, the HS-CONT group had higher (P < 0.05) serum corticosterone concentrations compared with the CONT and supplemented groups. The CONT group had higher (P < 0.05) villus height, width, surface area, and crypt depth compared with the HS-CONT group. On d 21, the HS-PM had higher (P < 0.05) villus width and surface area compared with HS-CONT group. On d 42, the HS-SYN had higher (P < 0.05) villus width and crypt depth compared with the HS-CONT group. These results showed that chronic HS reduces broiler production performance, intestinal microarchitecture, and increases adrenal hormone concentrations. Also, supplementation of the MOS prebiotic and the PM can partially lessen these changes.

Alleviation of cyclic heat stress in broilers by dietary supplementation of mannan-oligosaccharide and Lactobacillus-based probiotic: Dynamics of cortisol, thyroid hormones, cholesterol, C-reactive protein, and humoral immunity

Heat stress (HS), one of the major problems of tropical and subtropical countries, adversely affects the production performance of poultry. Keeping this in view, the present study was designed to investigate some of the biological markers of HS in broilers as modulated by dietary supplementation of mannan-oligosaccharide (MOS) and a Lactobacillus-based probiotic (LBP), either alone or in combination. Two hundred fifty 1-d-old-chicks were randomly divided into 5 groups. From d 22, the birds were either kept at the thermoneutral zone (TN) or exposed to HS to the conclusion of study, d 42. Birds were fed either a corn-based basal diet (TN and HS groups) or the same diet supplemented with 0.5% MOS (HS-MOS group), 0.1% LBP (HS-LBP group), or their combination. Birds were immunized against Newcastle disease virus on d 4 (intraocular; live attenuated) and d 20 (drinking water; live attenuated) and infectious bursal disease virus on d 8 (intraocular; live intermediate strain) and d 24 (drinking water; live attenuated). Birds were killed on d 42 to collect serum for determination of cortisol, thyroid hormones, cholesterol, C-reactive protein, and postvaccinal antibody titers. Results revealed that dietary supplementations decreased (P < 0.05) the serum cortisol and cholesterol concentrations and increased (P < 0.05) thyroxine concentration compared with the HS group without affecting triiodothyronine concentration. The percentage of the C-reactive protein-positive birds was higher (P < 0.05) in the HS group compared with the TN group. Dietary supplementations improved humoral immunity against Newcastle disease virus and infectious bursal disease virus during HS. In conclusion, dietary supplementation of either MOS or LBP alone or in combination can reduce some of the detrimental effects of HS in broilers.

Molecular analysis of the caecal and tracheal microbiome of heat-stressed broilers supplemented with prebiotic and probiotic.

The gastrointestinal tract commensal microbiome is important for host nutrition, health and immunity. Little information is available regarding the role of these commensals at other mucosal surfaces in poultry. Tracheal mucosal surfaces offer sites for first-line health and immunity promotion in broilers, especially under stress-related conditions. The present study is aimed at elucidating the effects of feed supplementations with mannanoligosaccharides (MOS) prebiotic and a probiotic mixture (PM) on the caecal and tracheal microbiome of broilers kept under chronic heat stress (HS; 35 ± 2°C). Day-old chickens were randomly divided into five treatment groups: thermoneutral control (TN-CONT), HS-CONT, HS-MOS, HS-PM and HS synbiotic (fed MOS and PM). Caecal digesta and tracheal swabs were collected at day 42 and subjected to DNA extraction, followed by polymerase chain reaction denaturing gradient gel electrophoresis (PCR-DGGE) and pyrosequencing. The PCR-DGGE dendrograms revealed significant (49.5% similarity coefficients) differences between caecal and tracheal microbiome. Tracheal microbiome pyrosequencing revealed 9 phyla, 17 classes, 34 orders, 68 families and 125 genera, while 11 phyla, 19 classes, 34 orders, 85 families and 165 genera were identified in caeca. An unweighted UniFrac distance metric revealed a distinct clustering pattern (analysis of similarities, P = 0.007) between caecal and tracheal microbiome. Lactobacillus was the most abundant genus in trachea and caeca and was more abundant in caeca and trachea of HS groups compared with the TN-CONT group. Distinct bacterial clades occupied the caecal and tracheal microbiomes, although some bacterial groups overlapped, demonstrating a core microbiome dominated by Lactobacillus. No positive effects of supplementations were observed on abundance of probiotic bacteria.