RESUMO
1. Male chickens of 7 genetic lines, consisting of two pure sire and two pure dam populations, a commercial broiler cross and two slow-growing chicken lines (Label Rouge, LR and Mechelse Koekoek, MK) were reared from 1 to 37 d of age. The chickens received a two-phase dietary regime and were subjected to low ambient temperature. 2. The experimental aim was to investigate relationships between susceptibility to ascites and heat production. 3. Body weight gain (BWG), food intake and food conversion ratio (FCR) were determined. Ascites mortality, arterial pressure index (API=right ventricular/total ventricular weight ratio), haematocrit values, proportional lung weight (lung weight/body weight x 100), plasma thyroid hormones (thyroxine, T4 and triiodothyronine, T3) and arterial blood gas pressures (pCO2 and pO2) were determined. The heat production per kg metabolic body weight (H/W0.75) and total heat production (H) were calculated for the period 16 to 33 d using an energy balance study according to the comparative slaughter method. 4. The two breeder sire lines had high BWG and low FCR and high but different incidences of ascites compared with the slow-growing ascites resistant LR and MK lines with notable high FCR. The broiler cross and slower-growing breeder dam lines had a similar and relatively lower incidence of ascites mortality. 5. The fast-growing chickens had low H/W0.75 values compared with slow-growing lines. 6. These fast-growing breeder sires had lower plasma thyroid hormone, reduced proportional lung weights, low arterial pO2 and high arterial pCO2 pressures compared with the slower-growing lines. 7. In conclusion, ascites incidence was associated with lower heat production per metabolic body weight and therefore a lower oxygen requirement per metabolic weight.
Assuntos
Ascite/veterinária , Galinhas/metabolismo , Metabolismo Energético/fisiologia , Doenças das Aves Domésticas/fisiopatologia , Animais , Ascite/genética , Ascite/metabolismo , Ascite/fisiopatologia , Regulação da Temperatura Corporal/fisiologia , Galinhas/genética , Análise por Conglomerados , Suscetibilidade a Doenças/veterinária , Ingestão de Alimentos , Genótipo , Hematócrito/veterinária , Masculino , Oxigênio/metabolismo , Pressão Parcial , Doenças das Aves Domésticas/genética , Doenças das Aves Domésticas/metabolismo , Distribuição Aleatória , Temperatura , Hormônios Tireóideos/sangue , Aumento de PesoRESUMO
1. Protein synthesis, net deposition and breakdown was studied in the gastrocnemius muscles of growing rats between weaning and 90 days of age. 2. Fractional protein synthetic rates declined from 30.02% at 25 days to 7.41% at 90 days. 3. The rate of protein degradation follows a similar pattern to that of protein synthesis. A linear relationship was found. 4. The break in the growth curve between 30 and 31 days was also observed in protein metabolism.