ABSTRACT
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.
ABSTRACT
The objective of this study was to evaluate the health status, productive performance and carcass traits of growing rabbits housed in pen with litter and conventional cage. At 35 d, 54 crossbred rabbits (New Zealand White vs. Botucatu) were randomly housed in pen with litter (6 pens, 6 rabbits/pen, 2.3 rabbits/m²) or cage (6 cages, 3 rabbits/cage, 8.3 rabbits/m²) and kept until the age of slaughter at 77 d. To simulate farm conditions, the rabbits that were housed in pen have not been previously adapted to this system. There was greater intensity of dirt and mucus occurrence in the rabbits housed in pens in first period, but the mucus occurrence practically disappeared in the later period. For performance, the rabbits housed in cages had a higher live weight at 56 d (1714 vs. 1506 g; P0.05) in the posterior period (56 to 77 d). There was no effect (P>0.05) of housing system for carcass yield, dissectible fat and hind leg yield. It may be suggested that rabbits adapt to the floor over time. Therefore, it is indicated the adoption of this system for growing rabbits.
O objetivo deste estudo foi avaliar o estado sanitário, o desempenho produtivo e as características de carcaça de coelhos em crescimento alojados em piso com cama e em gaiola convencional Aos 35 dias, 54 coelhos mestiços (Nova Zelândia Branco x Botucatu) foram alojados aleatoriamente em piso com cama (6 boxes; 6 coelhos/box; 2,3 coelhos/m²) ou em gaiola (6 gaiolas; 3 coelhos/gaiola; 8,3 coelhos/m²) e mantidos até a idade de abate, aos 77 dias. Para simular as condições de granja, os coelhos alojados em piso não foram previamente adaptados a este sistema. Houve maior intensidade de sujeira e ocorrência de muco nos coelhos alojados em piso no primeiro período, entretanto, esta ocorrência praticamente desapareceu no período posterior. Para o desempenho, os coelhos alojados em gaiola apresentaram maior peso vivo aos 56 dias (1714 vs. 1506 g; P0,05) os resultados de melhor desempenho no período posterior (56 a 77 dias). Não houve efeito (P>0,05) de sistema de alojamento para os rendimentos de carcaça referência, gordura dissecável e de pernil. Pode-se sugerir a ocorrência de adaptação dos coelhos ao piso, ao longo do tempo. Portanto, é indicada a adoção do sistema de alojamento em piso com cama para coelhos em crescimento.
Subject(s)
Animals , Rabbits , Sheltering , Animals, Domestic/growth & development , Health SurveillanceABSTRACT
The objective of this study was to evaluate the health status, productive performance and carcass traits of growing rabbits housed in pen with litter and conventional cage. At 35 d, 54 crossbred rabbits (New Zealand White vs. Botucatu) were randomly housed in pen with litter (6 pens, 6 rabbits/pen, 2.3 rabbits/m²) or cage (6 cages, 3 rabbits/cage, 8.3 rabbits/m²) and kept until the age of slaughter at 77 d. To simulate farm conditions, the rabbits that were housed in pen have not been previously adapted to this system. There was greater intensity of dirt and mucus occurrence in the rabbits housed in pens in first period, but the mucus occurrence practically disappeared in the later period. For performance, the rabbits housed in cages had a higher live weight at 56 d (1714 vs. 1506 g; P<0.001), as well as BWG (46.4 vs. 36.7 g/d, P<0.001) and better FC (2.75 vs. 3.33; P<0.05) from 35 to 56 d. However, these animals did not show the best performance (P>0.05) in the posterior period (56 to 77 d). There was no effect (P>0.05) of housing system for carcass yield, dissectible fat and hind leg yield. It may be suggested that rabbits adapt to the floor over time. Therefore, it is indicated the adoption of this system for growing rabbits.(AU)
O objetivo deste estudo foi avaliar o estado sanitário, o desempenho produtivo e as características de carcaça de coelhos em crescimento alojados em piso com cama e em gaiola convencional Aos 35 dias, 54 coelhos mestiços (Nova Zelândia Branco x Botucatu) foram alojados aleatoriamente em piso com cama (6 boxes; 6 coelhos/box; 2,3 coelhos/m²) ou em gaiola (6 gaiolas; 3 coelhos/gaiola; 8,3 coelhos/m²) e mantidos até a idade de abate, aos 77 dias. Para simular as condições de granja, os coelhos alojados em piso não foram previamente adaptados a este sistema. Houve maior intensidade de sujeira e ocorrência de muco nos coelhos alojados em piso no primeiro período, entretanto, esta ocorrência praticamente desapareceu no período posterior. Para o desempenho, os coelhos alojados em gaiola apresentaram maior peso vivo aos 56 dias (1714 vs. 1506 g; P<0,001), bem como, maior ganho de peso diário (46,4 vs. 36,7 g/d; P<0,001) e melhor conversão alimentar (2,75 vs. 3,33; P<0,05), no período de 35 a 56 dias. Entretanto, estes animais não mantiveram (P>0,05) os resultados de melhor desempenho no período posterior (56 a 77 dias). Não houve efeito (P>0,05) de sistema de alojamento para os rendimentos de carcaça referência, gordura dissecável e de pernil. Pode-se sugerir a ocorrência de adaptação dos coelhos ao piso, ao longo do tempo. Portanto, é indicada a adoção do sistema de alojamento em piso com cama para coelhos em crescimento.(AU)
Subject(s)
Animals , Rabbits , Animals, Domestic/growth & development , Sheltering , Health SurveillanceABSTRACT
The objective of this study was to evaluate the health status, productive performance and carcass traits of growing rabbits housed in pen with litter and conventional cage. At 35 d, 54 crossbred rabbits (New Zealand White vs. Botucatu) were randomly housed in pen with litter (6 pens, 6 rabbits/pen, 2.3 rabbits/m²) or cage (6 cages, 3 rabbits/cage, 8.3 rabbits/m²) and kept until the age of slaughter at 77 d. To simulate farm conditions, the rabbits that were housed in pen have not been previously adapted to this system. There was greater intensity of dirt and mucus occurrence in the rabbits housed in pens in first period, but the mucus occurrence practically disappeared in the later period. For performance, the rabbits housed in cages had a higher live weight at 56 d (1714 vs. 1506 g; P