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Effects of Dietary Electrolyte Balance and Digestible Threonine on Intestinal Morphology, Microbial Oopulation and Digestibility of Broilers Subjected to Heat Stress Conditions
2022
Ghasemi, Hossein Ali
BACKGROUND: Reducing the protein and amino acid content of diet or altering the dietary electrolyte balance were suggested as the effective strategies to prevent the harmful effects of the heat stress in poultry.OBJECTIVES: This study surveyed the effects of various levels of threonine and dietary cation-anion balance on the broiler chickens under the heat stress conditions.METHODS: 700 one-day-old male broilers (Ross 308) were used for 6 weeks under high- temperature conditions. This experiment was conducted using a 2 × 3 + 1 factorial experiment based on a completely randomized design, with 7 treatments (5 replicates per treatment and 20 birds per replicate). Experimental factors included two threonine concentrations (recommended level and 10 % above recommended level) and three dietary electrolyte balances (175, 250, and 325 mEq/kg). The control group considered the treatment with a normal threonine concentration (recommended level) and a dietary electrolyte balance of 250 mEq/kg under optimal temperature conditions.RESULTS: Although there was no interaction between threonine level and electrolyte balance, the electrolyte balance of 175 meq/kg increased the performance index compared to the electrolyte balance of 250 or 325 mEq/kg (P<0.05). The villus height to crypt depth ratio and villus surface area in the jejunum improved with an electrolyte balance of 175 or 250 mEq/kg (P<0.05). A decrease in the dietary electrolyte balance increased in the nitrogen-corrected apparent metabolizable energy (P<0.05). Besides, an increase in the population of lactobacilli and bifidobacteria in the cecum, as well as an increase in protein digestibility, were observed by increasing levels of threonine in the diet (P<0.05).CONCLUSIONS: Based on these results, a high level of threonine or a low electrolyte balance in diet (175 mEq/kg) may improve the performance, metabolizable energy, and intestinal microbial flora of broilers reared under heat stress.
اظهر المزيد [+] اقل [-]Effect of serial in vivo passages on the adaptation of H1N1 avian influenza virus to pigs
2022
Urbaniak, Kinga | Kowalczyk, Andrzej | Pomorska-Mól, Małgorzata | Kwit, Krzysztof | Markowska-Daniel, Iwona
The lack of proofreading activity of the viral polymerase and the segmented nature of the influenza A virus (IAV) genome are responsible for the genetic diversity of IAVs and for their ability to adapt to a new host. We tried to adapt avian IAV (avIAV) to the pig by serial passages in vivo and assessed the occurrence of point mutations and their influence on viral fitness in the pig’s body. A total of 25 in vivo avIAV passages of the A/duck/Bavaria/77 strain were performed by inoculation of 50 piglets, and after predetermined numbers of passages 20 uninoculated piglets were exposed to the virus through contact with inoculated animals. Clinical signs of swine influenza were assessed daily. Nasal swabs and lung tissue were used to detect IAV RNA by real-time RT-PCR and isolates from selected passages were sequenced. Apart from a rise in rectal temperature and a sporadic cough, no typical clinical signs were observed in infected pigs. The original strain required 20 passages to improve its replication ability noticeably. A total of 29 amino-acid substitutions were identified. Eighteen of them were detected in the first sequenced isolate, of which 16 were also in all other analysed strains. Additional mutations were detected with more passages. One substitution, threonine (T) 135 to serine (S) in neuraminidase (NA), was only detected in an IAV isolate from a contact-exposed piglet. Passaging 25 times allowed us to obtain a partially swine-adapted IAV. The improvement in isolate replication ability was most likely related to S654 to glycine (G) substitution in the basic protein (PB) 1 as well as to aspartic acid (D) 701 to asparagine (N) and arginine (R) 477 to G in PB2, glutamic acid (E) 204 to D and G239E in haemagglutinin and T135S in NA.
اظهر المزيد [+] اقل [-]Effect of in ovo Injection of L-Threonine on Hatchability Followed by post-hatch Extra Level of Dietary Threonine on the Performance of Broilers
2022
Gehad E. Eisa | Samar Abdelfatah | Hossam A. Abdellatif | Fathy F. Mohamed
The aim of this study was to examine the effect of in ovo injection of L-threonine (L-Thr) on hatchability, growth performance, antioxidant capacity, carcass traits, immune organs weight, and intestinal histomorphology of Ross 308 broilers chicks. On day 18 of incubation, 258 fertile eggs were randomly allotted into 3 sets: non-injected group (NC group), saline injected group (sham control SC group), and (Thr group) L-Thr injected group. After hatch, each set was allocated into 2 groups (3 replicates of 10 birds/ replicate) and were fed on a basal diet (calculated Thr content, 0.87 %) supplemented with 0 (CON group), and 3 g/kg L-Thr, respectively. The groups were divided as follows: G1, G2, G3, G4, G5 and G6 where G1 is non injected group and fed basal diet, G2 saline injected and fed basal diet, G3 threonine injected and fed basal diet, G4 non injected and fed threonine supplemented diet, G5 saline injected and fed threonine supplemented diet and G6 threonine injected and fed threonine supplemented diet. Growth performance parameters were measured during different periods of the trial. At the end of rearing period serum antioxidative parameters (SOD and MDA) were measured, carcass traits and relative immune organs weight were calculated, in addition to intestinal histomorphology. Addition of Thr positively affected the FCR, and feed intake of broiler chicks compared to sham and control (p < 0.05) groups. Dietary Thr supplementation increased relative weight of spleen and thymus compared to the control non supplemented group and improved intestinal histomorphology. In conclusion, in ovo injection and dietary supplementation of L-Thr can improve growth performance, immunity of broiler chickens that may be mediated by the development of immune organs and improving the intestinal morphology of broilers as demonstrated by higher ratio of villus height to crypt depth.
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