Bone densitometry as an indicator of percentage tibia ash in broiler chicks fed varying dietary calcium and phosphorus levels

Abstract

The relative sensitivity of tibia bone mineral content (BMC) and density (BMD), percentage ash (ash), and shear force as indicators for dietary Ca and P was compared in 3-wk-old broiler chicks. One hundred eight 7-d-old chicks were grouped by weight into 6 blocks of 3 cages each with 6 birds per cage. Three corn-soybean meal-based diets were randomly assigned to cages within each block. The diets were low P, medium P, and adequate P and were formulated to contain 4.0, 5.1, and 7.8 g of total P/kg feed, respectively; and 5.1, 6.7, and 10.0 g of Ca/kg feed, respectively. The chicks were fed the experimental diets for 14 d. On d 22, chicks were killed, and tibiae were removed from 3 birds/cage. Weight gain, feed intake, feed efficiency, BMC, BMD, shear force, and ash were determined. The BMC and BMD were determined using dual energy x-ray absorptiometry. Correlations among the various bone status variables and dietary Ca and P were determined. Growth performance criteria and ash increased linearly, and BMC and BMD increased linearly and quadratically as dietary concentrations of Ca and P increased. The correlation coefficient between dietary Ca and BMC, BMD, shear force, or ash was 0.89, 0.91, 0.50, or 0.89, respectively; and between dietary P and BMC, BMD, shear force, or ash was 0.88, 0.91, 0.48, or 0.89, respectively. The correlation coefficient between ash and BMC, BMD, or shear force was 0.92, 0.93, or 0.67, respectively. The correlation coefficients for linear regression between shear force and BMC or BMD was 0.56. The regression model for predicting percentage ash using BMD was as follows: percentage ash = 24 + (240 x BMD) with an r2 of 86%. It is concluded that in broiler chicks, tibia ash, BMC, and BMD may be more sensitive than shear force as indicators of dietary Ca and P concentrations and that BMD as measured by dual energy x-ray absorptiometry may be used to predict percentage of tibia ash.

Reduction of the nutritional values of diets for hens through supplementation with phytase

“…Onyango et al (2003) also found a high correlation between the level of available P in the feed and the ash content in the shank of broiler chicks from 1 to 21 days of age. Similarly, Silva et al (2008) evaluated the phytase on increasing levels of available phosphorus in the diet of laying hens and confirmed that the enzyme enhances the bone strength of the birds with the addition of phytase.…”

A Mixture of Thyme, Quillaja, and Anise at Different Nutrient Density on Growth Performance, Nutrient Digestibility, Meat Quality, Organ Weight, Cecal Bacteria, Excreta Moisture, and Bone Contents in Broiler Chicks

“…However, there were no significant effects of PFA on Ca or P contents in the bones of birds fed minerals and protein reduced diet supplemented with PFA. Onyango et al (2003) indicated that as the levels of dietary calcium and phosphorus increased the bone mineralization concentrate also increased linearly due to an increase in the levels of calcium and phosphorus. This implies that when the levels of Ca and P in the diet decrease, the amount of calcium and phosphorus required for mineralization will also decrease.…”

Efeito da densidade de criação e do grupo genético sobre a composição mineral e desenvolvimento de ossos longos de frangos de corte

“…Apesar dos programas de melhoramento genético conduzidos pelas empresas buscarem os mesmos objetivos -maior rendimento de peito e de coxa, estas linhagens apresentam algumas diferenças genéticas entre si, expressas na velocidade de crescimento, principalmente nas primeiras semanas de vida. Esta alta atividade metabólica inicial tem sido responsabilizada pela ocorrência de diversos problemas metabólicos, tais como a ascite e a síndrome da morte súbita, e também de algumas anomalias ósseas, tais como a discondroplasia tibial (PRAUL et al, 2000).…”

“…Dentre os parâmetros químicos, o teor de matéria mineral da tíbia tem sido o principal método pelo qual a mineralização óssea tem sido avaliada (HALL et al, 2003). Onyango et al (2003) concluíram que a densitometria óssea poderia ser usada para estimar a porcentagem de matéria mineral na tíbia de frangos de corte. A densitometria óptica radiográfica é uma das metodologias utilizadas para inferir o conteúdo mineral dos ossos, através de suas imagens radiográficas (LOUZADA et al, 1998).…”