Energy utilization and requirement of broiler breeders during the production phase.

This study aimed to evaluate energy utilization and propose models for metabolizable and net energy requirements in broiler breeders during the egg production phase. Sixty Cobb500 broiler breeders aged between 29 and 65 wk were randomly assigned to 3 feeding levels. At each age, 6 birds were adapted for 8 d to 3 levels of metabolizable energy intake (MEi), established based on the amount of feed allocated: 1) the amount of feed recommended in the guideline, 2) 25% above, and 3) 25% below. The birds were housed in respirometry chambers for 6 d (1 adaptation, 4 feeding state, 1 fasting) to measure oxygen consumption and carbon dioxide production to calculate heat production (HP) and fasting HP (FHP). Daily measurements of feed intake, egg weight, egg production, and total excreta were recorded. Variables of MEi, HP, and retained energy (RE) in the egg were calculated, while RE in the body and its partitioning into fat and protein in the egg and body were calculated from MEi, total HP (THP), and RE in the egg. Statistical analysis involved linear regression of multiple factors with MEi and age (categorical) as the independent variables. Pearson correlation analysis was conducted to investigate the relationship between visceral mass and the evaluated variables. The study proposed mixed models for developing models of energy requirements for both metabolizable (ME) and net systems (NE). The study found that FHP (average 259 ± 20.08 kJ/kg0.75*d) remained constant throughout the production cycle regardless of the MEi level (P > 0.05). The efficiency of energy utilization for depositing protein and fat in the body changed with the bird's age. The lower error model was considered to select ME requirements for maintenance, egg, and gain efficiencies, disregarding the effect of age. The efficiencies were 0.89, 0.78, and 0.80 for maintenance, gain, and egg production, respectively. The NE was unaffected by age and showed a lower error than the ME model. The NE system was found to be more accurate in expressing the energy requirements of broiler breeders.

Digestible protein levels and metabolic responses in juvenile piapara (Megaleporinus obtusidens) / Níveis de proteínas digestíveis e respostas metabólicas em juvenis de piapara (Megaleporinus obtusidens)

This study aimed to determine the effects of dietary digestible protein (DP) on growth and physiological indicators in piapara. Three hundred piapara juveniles (24.0 ± 1.3 g) were distributed in 20 tanks of 130 L (15 fish/tank) with continuous aeration and water. Five isoenergetic diets (14.0 MJ·kg-1) were formulated to contain increasing levels of DP (21, 24, 27, 30 and 33%). After 77 days of feeding, increasing levels of digestible protein influenced final weight, specific growth rate and weight gain linearly (p < 0.05). Water ammonia concentration and liver alanine aminotransferase activity also showed a linear effect with an increasing DP level (p < 0.05), but no relationship was found between DP level and serum ammonia (p > 0.05). There was no linear and quadratic effect for hepatosomatic index, liver glycogen and liver lipid content (p > 0.05). On the other hand, the muscle lipid content decreased linearly with the increase in the DP level (p < 0.05), while the mesenteric fat index showed a linear and quadratic effect (p < 0.05) with an increasing curve until the peak of 25.77% DP. The activity of the hepatic malic enzyme also followed a quadratic pattern (p < 0.05) with a maximum point of 27.08% of DP. This contrasts with the hepatic enzyme glucose-6-phosphate dehydrogenase, which increased linearly with the increase in the DP level (p < 0.05). The results showed better productive performance for fish fed with the highest levels of DP, though greater excretion of ammonia in the water was also shown. Diets below 27% DP resulted in greater energy reserve, amino acid catabolism and lipogenesis. Therefore, the inclusion of 28 to 30% DP in the diet will be ideal for growth and physiological responses in piapara.(AU)

Este estudo teve como objetivo determinar os efeitos da proteína digestível (PD) da dieta sobre o crescimento e indicadores fisiológicos em piapara. Trezentos juvenis de piapara (24 ± 1,3 g) foram distribuídos em 20 tanques de 130 L (15 peixes/tanque) com aeração contínua e água. Cinco dietas isoenergéticas (14,0 MJ·kg-1) foram formuladas para conter níveis crescentes de PD (21, 24, 27, 30 e 33%). Após 77 dias de alimentação, níveis crescentes de proteína digestível influenciaram o peso final, taxa de crescimento específico e ganho de peso de forma linear (p<0,05). A concentração de amônia na água e a atividade hepática da alanina aminotransferase também apresentaram efeito linear com o aumento do nível de PD (p < 0,05), mas não foi encontrada relação entre o nível de PD e amônia sérica (p > 0,05). Não houve efeito linear nem quadrático no índice hepatossomático, no glicogênio hepático e na concentração de lipídios hepáticos (p > 0,05). Por outro lado, o conteúdo de lipídio muscular diminuiu de forma linear com o aumento do nível de PD (p < 0,05), enquanto o índice de gordura mesentérica apresentou efeito linear e quadrático (p < 0,05) com curva crescente até o ponto máximo em 25,77% de PD. A atividade hepática da enzima málica também seguiu um padrão quadrático (p < 0,05) com ponto máximo em 27,08% de PD, diferentemente da enzima glicose-6-fosfato desidrogenase hepática, que aumentou linearmente com o aumento do nível de PD (p < 0,05). Os resultados mostraram melhor desempenho produtivo para os peixes alimentados com os maiores níveis de PD. Por outro lado, também proporcionaram maior excreção de amônia na água. Dietas abaixo de 27% PD resultaram em maior reserva energética, catabolismo de aminoácidos e lipogênese. Portanto, a inclusão de 28 a 30% PD na dieta será ideal para o crescimento e respostas fisiológicas em piaparas.(AU)

Effect of Dietary Tetramethylpyrazine on Egg Production, Nutrient Retention and Cecal Bacterial Diversity in Aged Laying Hens

This study aimed to investigate the effect of tetramethylpyrazine (TMP) supplementation on egg production, nutrient retention and cecal microbiota diversity using 288 commercial Hy-Line brown hens as of wk 75 to 86. Four treatments consisted of TMP addition at 0 (control, basal diet), 100, 150 and 200 mg/kg of diet. The results showed that diets supplemented with TMP addition improved egg-laying rate as of wk 77 compared to the control, which led to an increase (p<0.001) of egg mass by 97-225 g/hen throughout the whole trial, and a linear increase (p=0.003) of egg mass to the incremental TMP doses was found. At wk 86, the apparent digestibilities of dry matter and crude protein were enhanced (p<0.05), exhibiting consistent linear increases (p≤0.033) with the TMP doses. However, TMP did not cause alpha and beta diversity of cecal microbiota. The results suggest that TMP can be an additive to improve egg production and nutrient digestibility of aged laying hens.(AU)