Phosphorus utilization in finishing broiler chickens: Effects of dietary calcium and microbial phytase

Abstract

A decrease in dietary P, especially in finishing broilers (21 to 38 d old), is a crucial issue in poultry production from an environmental and economic point of view. Nevertheless, P must be considered together with other dietary components such as Ca and microbial phytase. Different corn and soybean meal-based diets varying in Ca [low (LCa) 0.37, medium (MCa) 0.57, and high (HCa) 0.77%], and nonphytate P [nPP; low (LnPP) 0.18 and high (HnPP) 0.32%] content were tested with and without microbial phytase [0 or 500 phytase units (FTU)/kg]. Feed intake, BW gain, bone mineralization, and mineral retention were examined in 144 Ross PM3 broilers (22 to 38 d old) reared in individual cages. Growth performance was not significantly affected by the treatments. Nevertheless, a numerical decrease of ADG and ADFI was observed in HCa-LnPP and LCa-HnPP associated with an increase of feed conversion ratio. Decreased dietary Ca reduced tibia ash content (Ca, linear: P < 0.001; quadratic: P = 0.034) and tibia ash weight for the highest level of nPP (Ca × nPP; P = 0.035). In parallel, increasing dietary Ca reduced the flow of retained P (P = 0.022) but also tibia ash weight in LnPP diets (Ca × nPP; P = 0.035). The responses of the animals in terms of tibia ash content and P retention were improved by the addition of microbial phytase especially for the lowest P diets (nPP × phytase, P = 0.021 and P = 0.009; respectively). Phytase increased dry tibia weight, bone breaking strength, and tibia diameter in broilers fed the highest Ca diets (Ca × phytase; P < 0.05). We conclude that is possible to decrease P levels in finishing broilers, if the Ca content is appropriate. Nevertheless, decreasing the dietary P and Ca cannot allow a maximization of bone mineralization, but the optimal threshold remains to be determined.

Nutritional geometry of calcium and phosphorus nutrition in broiler chicks. Growth performance, skeletal health and intake arrays

“…With increasing inclusion of nPP in diets, feed intake and BW gain rapidly increased. Previous studies with low nPP (2 g/kg) and high Ca concentrations (9 g/kg) reported reduced growth performance (Plumstead et al, 2008;Rousseau et al, 2012), which is consistent with the findings reported in the present paper. Rama Rao et al (2006) reported similar effects where increasing dietary Ca concentration from 6 to 9 g/kg between 22 to 42 days was deleterious for growth and bone mineralisation when dietary nPP was not increased concurrently.…”

Effect of dietary calcium concentrations in low non-phytate phosphorus diets containing phytase on growth performance, bone mineralization, litter quality, and footpad dermatitis incidence in growing broiler chickens

“…The observation that growth performance including BW, BWG, FI, and mortality was not affected by dietary treatments agrees with Rousseau et al [19] who reported that increasing Ca concentrations from 3.7 to 7.7 g/kg in diets had no effects on growth performance of growing broiler chickens. Our result indicates that the concentrations of Ca from 4.0 to 9.0 g/kg in low NPP diets containing phytase did not significantly limit growth performance of growing broiler chickens.…”

Effects of 1.25-Dihydroxycholecalciferol and Hydroalcoholic Extract of Withania Coagulans Fruit on Bone Mineralization and Mechanical and Histological Properties of Male Broiler Chickens

“…However, when Ca was decreased by 30%, a greater increase in Ca and P retention was observed in broilers fed the negative control diets. Considering that poultry cope with Ca and P deficiencies through an active regulatory phenomenon that leads to increased mineral utilization efficiency, bone criteria cannot be optimized if the mineral supply is not well balanced (Rousseau et al, 2012). Also, a three-way interaction of control, WC and 1.25-(OH) 2 D 3 treatments was observed on tibia bone diameter (p<0.05).…”

“…Rousseau et al (2012) reported that broilers fed the adequate dietary Ca presented normal tibia diameter, and emphasized the need for a balanced and adequate supply of Ca and P to optimize certain bone parameters. However, when Ca was decreased by 30%, a greater increase in Ca and P retention was observed in broilers fed the negative control diets.…”