Metabolism and requirements for calcium and phosphorus in the fast-growing chicken as affected by age

Abstract

Three series of experiments were conducted with fast-growing chickens in order: to evaluate the effects of dietary Ca and P on cholecalciferol metabolism and expression; to determine dietary Ca requirements; to determine dietary P requirements. The results of the first series confirmed previous results on the effects of dietary Ca and P on some variables of vitamin D metabolism and expression, Ca homeostasis and P metabolism in the young chicken (1-to 21-d-old), and extended them to older birds (22-to 43-d-old). The bone formation rate and the duodenal calbindin content were maintained at high levels until the age of 43 d. Dietary Ca or P restriction increased duodenal calbindin and decreased bone ash in both 22-and 43-d-old chickens, but the effect on bone ash was less pronounced in the 43-d-old birds than in the younger ones. These results suggest that: (a) the capabilities for adaptation to dietary Ca and P restriction remain high during the whole growing period; (b) the growing broilers express a high adaptive capability even when the diet contains the recommended Ca and P contents. The results of the second and third series of experiments suggest that: (c) unlike the Ca requirements of the 1-to 22-d-old chick, P requirements for growth and bone ash are similar, and are as high in the older chicks as in the younger ones (7·4-8·3 g P/kg or 4·8-5·7 g non-phytate P/kg diet); (d) although growth and bone ash in the 29-to 43-d-old chickens appear to be less sensitive to dietary Ca content, within a range close to the calculated P requirement, 10 g Ca/kg diet appears to be required for best tibia mineralization, and to a lesser extent for better growth at this age.

Effects of calcium to non-phytate phosphorus ratio and different sources of vitamin D on growth performance and bone mineralization in broiler chickens

“…The lowest Ca to NPP ratio of 1.14 damaged growth performance of broilers. Birds obtained the greatest BWG and FI at 42 d of age when the Ca to NPP ratio ranged from 2.27 to 2.33 in diets with 1α-OH-D 3 or 25-OH-D 3 as vitamin D. Previous research showed that the high Ca to NPP ratio of 4.0 depressed the BWG and FI of broilers (Li et al, 2012) and the optimal Ca to NPP ratio was 2.0 in broiler diets with vitamin D 3 as the vitamin D source (Bar et al, 2003;Rao et al, 2007).…”

“…The NRC (1994) recommended the Ca and NPP requirements of 10.0 and 4.5 g kg -1 (Ca/NPP = 2.22) in 1-to 21-d-old birds, and 9.0 and 3.5 g kg -1 (Ca/NPP = 2.57) in 22-to 42-d-old broilers. Further research showed that the highest performance and tibia mineralization of broilers were observed at a Ca to NPP ratio of 2.0 (Bar et al, 2003;Rao et al, 2007). These data suggest that the Ca to NPP ratio ranges from 2.0 to 2.6 in broiler diets.…”

“…Cholecalciferol (vitamin D 3 ) was used as a vitamin D source in the abovementioned research (Bar et al, 2003;Driver et al, 2005;Rao et al, 2007). 1α-hydroxycholecalciferol (1α-OH-D 3 ) and ) are derivatives of vitamin D. Their bioavailability is higher than that of vitamin D 3 .…”

Níveis nutricionais de fósforo disponível para aves de corte ISA Label criadas em semiconfinamento

“…As diferenças nas exigências de fósforo disponível entre os sexos podem ser decorrentes da maior eficiência alimentar dos machos em relação às fêmeas, pois apresentaram ganho de peso significativamente mais alto sob deficiência de Pd. Esses resultados estão de acordo com os obtidos por Bar et al (2003) que observaram menor exigência de Pd para o crescimento e deposição de cinzas na tíbia de frangos de corte machos em relação às fêmeas.…”

“…No entanto, os resultados obtidos neste trabalho para a fase de 1 a 28 dias de idade foram próximos, tanto para variáveis de desempenho quanto para os parâmetros ósseos. Os dados obtidos corroboram os encontrados por Bar et al (2003), que verificaram que as exigências em fósforo para ganho de peso e deposição de cinzas na tíbia dos frangos de corte em crescimento são similares. As exigências para máximo desempenho e melhores parâmetros ósseos não seguem, portanto, mesmo padrão e isso pode estar associado à idade e ao potencial genético dos animais.…”