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Abstract Background: Exogenous enzyme supplementation is an effective and cost-saving mechanism for increasing the availability of dietary nutrients by increasing digestion and reducing excretion. Objective: To evaluate the effects of phytase supplementation on performance, egg quality, and economic parameters in commercial laying hens fed reduced-nutrient diets from 70 weeks of age. Methods: Novogen White® commercial laying hens (n=256) were randomly allocated to four treatment groups, with eight replicates of eight hens in each group: PC (positive control): conventional diet not supplemented with phytase; diet with reduced levels (RN) of P (-0.12%), Ca (-0.10%), and ME (-14 kcal/kg), and supplemented with 300 phytase units (FTU/kg; RN300FTU); diet with reduced levels of P (-0.16%), Ca (-0.13%), ME (-18 kcal/kg), CP (-8%), synthetic amino acids (-0.01%), and supplemented with 600 FTU phytase/kg (RN600FTU); and diet with reduced levels of P (-0.18% P), Ca (-0.15%), ME (-20 kcal/kg), CP (-20%), synthetic amino acids (-0.01%), and supplemented with 900 FTU phytase/kg (RN900FTU). Results: The layers fed the RN300FTU diet had 2.68% higher egg production than those fed the PC diet. Egg mass produced by PC- and RN300FTU-fed hens was statistically similar. Eggshell thickness was increased in PC-fed hens. Feed cost for the RN900FTU diet was approximately 9% lower compared with that of the PC diet. Conclusion: The best performance and economic results were achieved when layers were fed a reduced-nutrient diet supplemented with 300 FTU phytase.

Resumen Antecedentes: La suplementación con enzimas exógenas es un mecanismo eficaz y económico para aumentar la disponibilidad de nutrientes dietéticos al aumentar la digestión y reducir la excreción. Objetivo: Evaluar los efectos de una dieta con reducción de nutrientes y suplementada con niveles incrementales de fitasa en ponedoras a partir de las 70 semanas de edad sobre su desempeño, calidad del huevo y parámetros económicos. Métodos: Un total de 256 ponedoras Novogen White® se asignaron al azar a cuatro grupos de tratamiento, con ocho réplicas de ocho gallinas en cada unidad experimental: Control positivo (PC) dieta convencional sin fitasa; dieta con niveles reducidos (RN) de P (-0,12%), Ca (-0,10%) y ME (-14 kcal/kg) y suplementada con fitasa (300 FTU/kg: NR300FTU); dieta con NR de P (-0,16%), Ca (-0,13%), ME (-18 kcal/kg), PB (-18%), aminoácidos sintéticos (-0,01%) y suplementada con fitasa (600 FTU/kg: NR600FTU); y dieta con RN de P (-0,18%), Ca (-0,15%), ME (-20 kcal/kg), PB (-20%), aminoácidos sintéticos (-0,01%) y suplementada con fitasa (900 FTU/kg: RN900FTU). Resultados: Las ponedoras alimentadas con RN300FTU presentaron una producción de huevos 2,68% mayor al PC. La masa de huevos producida por gallinas alimentadas con PC y RN300FTU fue estadísticamente semejante. El grosor de cáscara del huevo fue mayor para las gallinas alimentadas con dieta basal. El costo de alimentación de la dieta RN900FTU fue aproximadamente 9% menor que la dieta basal. Conclusión: Las ponedoras alimentadas con la dieta RN300FTU presentaron los mejores resultados económicos y zootécnicos.

Resumo Antecedentes: A suplementação de enzimas exógenas é um mecanismo eficaz e econômico para aumentar a disponibilidade de nutrientes da dieta, aumentando a digestão e reduzindo a excreção. Objetivo: Avaliar os efeitos das dietas com redução de nutrientes suplementadas com fitasse a galinhas poedeiras comerciais a partir das 70 semanas de idade sobre desempenho, qualidade dos ovos e parâmetros econômicos. Métodos: Um total de256 poedeiras Novogen White® foram distribuídas aleatoriamente a quatro grupos de tratamento, com oito repetições de oito galinhas em cada unidade experimental: PC (controle positivo): dieta convencional, sem fitasse; dieta com níveis reduzidos (RN) de P (-0,12%), Ca (-0,10%) e ME (-14 kcal/kg) e suplementada com fitasse de 300 FTU/kg (RN300FTU); dieta com níveis reduzidos de P (-0,16%), Ca (-0,13%), ME (-18 kcal/kg), PB (-18%), aminoácidos sintéticos (-0,01%) e suplementados com 600 Fitasse de FTU / kg (RN600FTU); e dieta com níveis reduzidos de P (-0,18% P), Ca (-0,15%), ME (-20 kcal / kg), PB (-20%), aminoácidos sintéticos (-0,01%) e suplementados com fitasse de 900 FTU/kg (RN900FTU). Resultados: As poedeiras alimentadas com NR300FTU apresentaram produção de ovos 2,68% maior do que as com a dieta PC. A massa de ovos produzida por galinhas alimentadas com PC e RN300FTU foi estatisticamente semelhante. A espessura da casca dos ovos foi melhor para galinhas alimentadas com PC. O custo de alimentação da dieta RN900FTU foi aproximadamente 9% menor em comparação com o da dieta de PC. Conclusão: Este estudo mostrou que as poedeiras alimentadas com dieta RN300FTU apresentaram os melhores resultados econômicos e zootécnico.

RESUMO

Metabolite profiles of chicken breast extracts and water mobility in breasts were studied using proton nuclear magnetic resonance (1H-NMR) spectroscopy and time-domain NMR (TD-NMR) relaxometry, respectively, using normal breast (NB), and wooden breast (WB) and white striping (WS) myopathies in broilers. One thousand eight hundred sixty broilers were raised to commercial standards, receiving the same diets that were formulated as per the different growth stages. At 49 D of age, 200 animals were slaughtered following routine commercial procedures, and at 4 h postmortem, the whole breast (pectoralis major muscle) was removed and visually inspected by an experienced meat inspector who selected NB (without myopathies) and samples with the presence of WS and WB myopathies. Fifteen breasts (5 each of NB, WS, and WB) were analyzed through TD-NMR relaxometry, and samples of approximately 20 g were taken from each breast and frozen at -80°C for metabolite profiling through 1H-NMR spectroscopy. Multivariate statistical analysis was used to evaluate the effect on water relaxometry and metabolite profile in accordance with the presence and type of myopathy in the breast. 1H-NMR data showed that the metabolite profiles in WS and WB breasts were different from each other and from NB. This pilot study shows that myopathies appear to be related to hypoxia, connective tissue deposition, lower mitochondrial function, and greater oxidative stress compared with NB. The longitudinal and transverse relaxation time of the breasts determined by TD-NMR relaxometry was shorter for NB than that for WS and WB, indicating greater water mobility in breasts affected by myopathies. 1H-NMR spectroscopy can be used to differentiate the metabolism of WS, WB, and NB, and TD-NMR has the potential to be a fast, simple, and noninvasive method to distinguish NB from WB and WS. As a practical application, the metabolomic profile as per the occurrence of breast myopathies may be used for a better understanding of these issues, which opens a gap to mitigate the incidence and severity of WS and WB. In addition, the present study brings an opportunity for the development of a new and objective tool to classify the incidence of breast myopathies through TD-NMR relaxometry.

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RESUMO

Considering the market availability of new commercial layer strains with distinct characteristics and behaviors, studies to update their nutritional requirements and to evaluate the need to adopt management practices, such as beak trimming, are needed. The objective of the present study was to evaluate the effects of dietary metabolizable energy (ME) levels and beak trimming on the live performance, egg quality, and economics of commercial layers. A total of 640 Novogen White layers were distributed according to a randomized experimental design in a 5 × 2 factorial arrangement (5 ME levels × 2 beak trimming treatments), totaling 10 treatments with 8 replicates of 8 hens each. The evaluated dietary ME levels were 2,600; 2,700; 2,800; 2,900; and 3,000 kcal/kg of feed. Layers were beak-trimmed once (7 days old) or twice (7 and 70 days old). Live performance and egg quality mesuraments and production economics were analyzed. Egg production was positively influenced by dietary ME levels. Feed intake (FI), feed conversion ratio (FCR), egg weight, albumen height, Haugh units, and eggshell strength were positively influenced by increasing dietary ME levels. Hens beak-trimmed once presented higher feed intake and worse FCR than those beak-trimmed twice. Beak trimming did not affect egg production, egg weight, albumen height, Haugh units, and eggshell strength. Production costs increased as dietary ME levels increased. Higher production cost was determined for hens beak-trimmed once than for those beak-trimmed twice. Total revenue was not influenced by the treatments. Gross margin was linearly decreased as dietary ME levels increased and was lower when hens were beak-trimmed once. Increasing dietary ME levels and beak trimming hens once reduce the economic viability of egg production.

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