Phosphorus bioavailability and digestibility in canola meals determined by different methods

phosphorus;canola meal

Hanna, Christina Denise ; Parsons ; Carl M.

关键词: phosphorus;    canola meal;   

Others  :  https://www.ideals.illinois.edu/bitstream/handle/2142/89059/HANNA-THESIS-2015.pdf?sequence=1&isAllowed=y

美国|英语

来源: The Illinois Digital Environment for Access to Learning and Scholarship

【 摘 要 】

Six experiments were conducted to determine P bioavailability for a new test high-protein canola meal (TCM), a conventional canola meal (CCM) and dehulled soybean meal (SBM) using different types of animal assays.Experiment 1 was a chick-growth bioassay conducted to determine relative P bioavailability in the TCM, CCM, and SBM relative to KH2PO4.A phosphorus-deficient cornstarch-dextrose-SBM basal diet was fed as Diet 1. Diets 2 and 3 had 0.05% or 0.10% P added from KH2PO4, respectively. The remaining diets had 12.5% or 25% TCM, CCM, or SBM added in place of cornstarch and dextrose.Bioavailability of P was estimated using the multiple-regression slope-ratio method where tibia ash was regressed on supplemental P intake.A linear increase in tibia ash was observed as the P level was increased by addition of KH2PO4, CCM, TCM, or SBM.Mean bioavailability values of P in the TCM, CCM, and SBM relative to KH2PO4 were 18, 15, and 34%, respectively.It was concluded that the bioavailable P content of the new TCM was statistically equal to the CCM.Experiment 2, an additional chick bioassay, was conducted to determine the effect of phytase enzyme (Optiphos, Huvepharma, Sofia, Bulgaria) on bioavailability of the P in the CMs. Diet 1 was a phosphorus-deficient TCM-cornstarch-dextrose diet, with the TCM as the only source of dietary P.Diets 2-4 had 0.05%, 0.10%, or 0.15% P added from KH2PO4, respectively.Diets 5 and 6 were the same as Diet 1 with 125 or 250 units phytase added per kg of diets, respectively.Diets 7-14 were the same as Diets 1-7 except that CCM was the CM source.Multiple-regression was used to regress bone ash on supplemental P intake and the slope-ratio method was used to determine P release by phytase.It was estimated that the addition of 125 or 250 units/kg of phytase greatly increased the bioavailable P content of the TCM by 0.05 and 0.10%, respectively, and the response to phytase was slightly lower for the CCM than TCM.The results indicated that phytase greatly and similarly increased the bioavailability of P in the TCM and CCM.Experiment 3 was an ad-libitum-fed chick experiment which evaluated the effect of phytase on P digestibility and (ileal) retention (excreta) values for CCM based on ileal and excreta contents, respectively.The chicks were fed a P - deficient cornstarch - dextrose CM basal diet (.13% available P) as Diet 1.Diets 2 and 3 were the basal diet plus 125 or 250 FTU/kg of phytase, respectively.On Day 22, the ileal digesta and excreta were collected and analyzed for P.Ileal P digestibility was 38.0%, 44.8%, and 46.6% for birds fed Diets 1-3, respectively.The P retention values were determined to be 38.7%, 47.3%, and 51.0% for Diets 1-3, respectively.Experiment 4 was a precision - fed chick assay conducted to determine the ileal P digestibility of CCM.The chicks were fed a nutritionally complete corn - SBM starter diet from Days 1 - 20.On Day 21, after fasting for 9 hours overnight, the chicks were tube fed 3, 6, or 9 g for CCM.Ileal digesta were collected four hours after feeding.Mean ileal P digestibility was determined to be 47.5% in chicks fed 6 g and 40% in chicks fed 9 g of CCM.Experiment 5 was conducted using a precision-fed rooster assay to determine P retention values for CCM. After withdrawal of feed for 24 hours, the roosters were tube-fed 8, 16, or 24 g of CCM.All excreta (feces + urine) were collected 48 hours after feeding.Phosphorus standardized retention values were 34.6%, 28.5%, and 23.1% for birds tube-fed 8, 16, and 24 g of CCM, respectively.Experiment 6 was an ad libitum-fed chick assay to determine the ileal P digestibility and retention of CCM with and without increasing levels of dietary supplemental Ca and Ca: P ratio.The chicks were fed a P deficient - dextrose - CCM basal diet (0.039% available P, 13.50% CCM) as Diet 1.Diets 2-4 contained increasing levels of 27%, 40.50%, or 54% added CCM, respectively.The Ca: available P ratio was maintained at a 2:1 ratio in Diets 1-4.Diets 5-8 were the same as Diets 1-4 but supplemental calcium was added so that the Ca: available P ratio was maintained at a 6:1 ratio.Diets were fed from Days 15-21 posthatch and excreta were collected on Days 21 and 22 and ileal digesta on Day 22.Phosphorus digestibility decreased with each increase in dietary CCM and also with increased Ca: P ratio.Phosphorus retention values also generally decreased with increased Ca: P ratio.The results of Experiments 3-6 indicated the P digestibility and retention values for CCM varied among balance methods and sometimes among levels of CCM fed.