Nutritional geometry of calcium and phosphorus nutrition in broiler chicks. The effect of different dietary calcium and phosphorus concentrations and ratios on nutrient digestibility

Abstract

A total of 600 Ross 308-day-old male broiler chicks were used in a 28 day digestibility study to investigate the interaction between dietary calcium (Ca) and non-phytate phosphorus (nPP) on the digestibility of minerals and amino acids. Diets were formulated to be nutritionally adequate except for Ca and nPP. Fifteen mash diets based on corn and soya bean meal with varying concentrations of Ca (6.4 to 12.0 g/kg) and nPP (2.4 to 7.0 g/kg) were used. Diets were clustered around total densities of Ca and nPP of 12, 13.5 or 15.0 (g/kg) and within each density, a range of five Ca : nPP ratios (1.14 : 1, 1.5 : 1, 2.0 : 1, 2.75 : 1 and 4.0 : 1) were fed. Birds had free access to feed and water throughout the study. At day 28, birds were euthanised for the determination of apparent ileal mineral and amino acid digestibility. Data were modelled in R version 2.15 using a linear mixed-effects model and interrogation of the data was performed by fitting a low order polynomial function. At high Ca concentrations, increasing nPP led to an increase in the apparent digestibility of minerals. Apparent ileal digestibility of phosphorus (P) was enhanced with increasing dietary nPP up to 5.5 g/kg beyond which no improvements were found. Maximal Ca digestibility was found in diets with > 8.0 g/kg Ca with concomitant low concentrations of nPP. Diets with a broader Ca : nPP ratio improved the digestibility of Ca but were deleterious to the digestibility of P. In this study, apparent digestibility of amino acids was broadly unaffected by dietary Ca and nPP concentrations. However, interactions between Ca and nPP were observed for the digestibility of glutamine, tyrosine and methionine (all P < 0.001). Nitrogen digestibility showed discrete optima around 10.0 and 5.0 g/kg nPP and Na digestibility was maximised around 8 to 9.0 g/kg Ca and 4.5 to 5.4 g/kg nPP. These data show that the ratio of Ca : nPP is more influential to mineral digestibility than the absolute dietary concentration of each macro mineral.

Interactive effects of phosphorus, calcium, and phytase supplements on products of phytate degradation in the digestive tract of broiler chickens

“…This confirms the results of Wilkinson et al. ( 2014 ), who also reported no interactions between Ca and NPP—added to broiler diets in several concentrations—on the prececal digestibility of most AA measured. However, these results contradict the results of Ravindran et al.…”

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

“…Samples were then placed into a muffle furnace and ashed for 12 h at 600°C. Diets and ileal digesta were analysed for digestibility metrics and are reported in Wilkinson et al (2014).…”

Feeding Asian pangolins: An assessment of current diets fed in institutions worldwide

“…Nutrient requirements of wild animal species are largely unknown and how they are fed is based on a "model" species for which there is already an understanding of their nutritional needs. Often domestic models such as dogs (Bellanger et al, 2015), cats (Vester et al, 2010), swine (Tajima & Aminov, 2015), poultry (Wilkinson, Bradbury, Thomson, Bedford, & Cowieson, 2014), rat (Robbins, 2012), horse (Hagen et al, 2015;Johnson, 2014), rhesus macaque (O'Sullivan et al, 2013), duck (Robbins, 2012), mink (Diez-Leon & Mason, 2016, goat (Weiss, Schook, & Wolfe, 2014), and sheep (Gattiker et al, 2014) are used. Choice of model species will depend on phylogenetic relatedness, similarity in feeding ecology and digestive morphology and physiology.…”