Performance, nutrient digestibility, and muscular evaluation of female broiler chickens fed different dietary protein levels and slaughtered at 38 or 46 days

ABSTRACT This study evaluated the effects of two protein levels and types of formulation on performance, nutrient metabolization, and myopathies of 390 female broilers from 21 to 46 days old distributed in a completely randomized design, with five treatments and six replicates of 13 broilers each. Treatments were two levels of protein (19.0 and 21.0%) in diets using only commercially available ingredients and three experimental formulations designed to keep similar the main nutrients that could influence nutritional performance (starch, fiber, ether extract), using unusual ingredients, with 19.0% (19E) or 21.0% (21E) crude protein and the third with 19.0% crude protein with amino acid levels similar to treatment 21P (19E+Aa). We studied broiler performance, nutrient digestibility, macroscopic muscular evaluation, and histological muscular evaluation. The design for the performance and myopathy assessment was a 5 × 2 factorial scheme, five diets × two ages (38 or 46 days). The worst feed conversion ratio was observed for the 19P treatment. Neither diet nor age had an effect on myopathies, however, older slaughter age increased the intensity of microscopic lesions. The diet 19P should be avoided and increased inclusion of lipids in diets improves nutrient utilization and, consequently, performance

Transmissible viral proventriculitis in naturally infected broilers

Submitted by Philipe Leao ([email protected]) on 2020-03-04T22:04:38Z No. of bitstreams: 1 Leao PA, 2019. Proventriculite viral transmissível em frangos de corte naturalmente infectados.pdf: 1210720 bytes, checksum: 36e537fb024d07c4473e6cc3582743e4 (MD5)Approved for entry into archive by Jane Campos ([email protected]) on 2020-03-16T14:50:25Z (GMT) No. of bitstreams: 1 Leao PA, 2019. Proventriculite viral transmissível em frangos de corte naturalmente infectados.pdf: 1210720 bytes, checksum: 36e537fb024d07c4473e6cc3582743e4 (MD5)Made available in DSpace on 2020-03-19T16:32:43Z (GMT). No. of bitstreams: 1 Leao PA, 2019. Proventriculite viral transmissível em frangos de corte naturalmente infectados.pdf: 1210720 bytes, checksum: 36e537fb024d07c4473e6cc3582743e4 (MD5) Previous issue date: 2019-02-28FAPEMIG - Fundação de Amparo à Pesquisa do Estado de Minas GeraisO vírus da proventriculite necrótica das aves (CPNV, do inglês, chicken proventricular necrosis vírus) tem sido estudado e indicado por alguns pesquisadores como o agente etiológico da proventriculite viral transmissível (TVP, do inglês, transmissible viral proventriculitis). Objetivou-se investigar a ocorrência de TVP (primeiro relato no Brasil), utilizando proventrículos de frangos de corte para avaliação histopatológica e identificação do gene VP1 do CPNV por RT- PCR e sequenciamento. Foram examinados 73 frangos provenientes de lotes da região Sudeste brasileira com histórico de atraso no desenvolvimento corporal e baixo peso. Os frangos eram da linhagem Cobb com 25 a 36 dias de idade. Os proventrículos foram avaliados macroscopicamente e pela histopatologia, estabelecendo escores para as lesões. Foram, também, avaliadas as diferenças entre espessura da parede do proventrículo e peso vivo, considerando o padrão Cobb 500. Frangos de todas as idades tiveram lesões histológicas e RT-PCR positivo, contudo, houve maior severidade e incidência de lesões aos 33 dias e maior positividade aos 28 dias de idade. Não houve associação ao comparar peso vivo pelo padrão Cobb 500, histopatologia e RT-PCR, quando o peso vivo foi corrigido retirando a influência dos lotes. No total, 73 proventrículos foram examinados macroscopicamente e por histopatologia e 67 também examinados por RT-PCR. Em 47,9% dos proventrículos, foram encontradas lesões características de TVP, principalmente infiltrado linfo-histioplasmocitário intersticial, necrose do epitélio glandular e ectasia glandular. Em 35,8% das aves detectou-se RT-PCR positivo. Somente 6,8% das aves apresentaram aumento da espessura da parede dos proventrículos. Proventrículos com lesão histológica de TVP tiveram espessura maior que aqueles sem lesão. Contudo, o baixo porcentual de alterações macroscópicas e a maior ocorrência de lesões histológicas sem aumento macroscópico da espessura da parede reforçam a hipótese de doença subdiagnosticada. O sequenciamento de um fragmento do gene VP1 do CNPV revelou similaridade genética entre 87,01% a 92,68% com outras sequências desse mesmo gene, relatado nos EUA, Reino Unido e Espanha. Este é o primeiro relato de TVP no Brasil e reforça o CPNV como agente da doença. No entanto mais estudos referentes aos efeitos na produtividade e coinfecções são necessários para melhor compreensão da doença.The chicken proventricular necrotic vírus (CPNV) has been studied and researches have indicating it as the etiologic agent of transmissible viral proventriculitis (TVP). The aim of this study was to investigate the occurrence of TVP (first report in Brazil), using broilers proventriculus to histopathology analysis and identification of the VP1 gene from CPNV by RT-PCR and sequencing. In the pathology department, 73 broilers from flocks of the Brazilian southeast region with history of decreased body weight and stunted growth were examined. The birds were Cobb with 25 to 36 days of age. The proventriculus were examined macroscopically and microscopically, and scores for the histological lesions were stablished. The difference in the proventicular wall thickness and body weight were also evaluated considering the pattern for Cobb 500 for body weight. Broilers from all ages had histopathologic lesions and were RT-PCR positive, however, there were higher histologic severity and incidence at 33 days of age and RT-PCR positivity in 28 days of age. There was no association between body weight by the Cobb 500 pattern, histopathology and RT-PCR when the body weight was corrected removing the flock influence. Totally, 73 proventriculus were examined macroscopically and microscopically and 67 also tested by RT-PCR. In 47,9% of the proventriculus, were observed microscopic lesions of TVP, mainly glandular epithelial necrosis, epithelial duct hyperplasia with replacement of glandular epithelium by ductal epithelium, expansion of the interstitial glandular space by inflammatory infiltrate as well as glandular ectasia. In 35,8% of the broilers the RT-PCR were positive for VP1. Only 6,8% of the broilers showed enlargement of the proventricular wall. Proventriculus with TVP histologic lesions had higher wall thickness. Nonetheless, the low percentage of proventriculus with microscopic lesions without proventriculus enlargement strengthen the hypothesis of subdiagnosed disease. The sequencing of a VP1 gene fragment from CPNV reveled genetic similarity between 87,01% and 92,68% in comparison with other sequences of this same gene reported in USA, United Kingdom and Spain. This is the first TVP report in Brazil and supports CPNV as the etiologic agent of TVP. Even so, more studies on the effects of the disease in productivity and coinfections are required to improve the comprehension of TVP

Performance, nutrient digestibility, and muscular evaluation of female broiler chickens fed different dietary protein levels and slaughtered at 38 or 46 days

This study evaluated the effects of two protein levels and types of formulation on performance, nutrient metabolization, and myopathies of 390 female broilers from 21 to 46 days old distributed in a completely randomized design, with five treatments and six replicates of 13 broilers each. Treatments were two levels of protein (19.0 and 21.0%) in diets using only commercially available ingredients and three experimental formulations designed to keep similar the main nutrients that could influence nutritional performance (starch, fiber, ether extract), using unusual ingredients, with 19.0% (19E) or 21.0% (21E) crude protein and the third with 19.0% crude protein with amino acid levels similar to treatment 21P (19E+Aa). We studied broiler performance, nutrient digestibility, macroscopic muscular evaluation, and histological muscular evaluation. The design for the performance and myopathy assessment was a 5 × 2 factorial scheme, five diets × two ages (38 or 46 days). The worst feed conversion ratio was observed for the 19P treatment. Neither diet nor age had an effect on myopathies, however, older slaughter age increased the intensity of microscopic lesions. The diet 19P should be avoided and increased inclusion of lipids in diets improves nutrient utilization and, consequently, performanc