title: Interactive effects of dietary adaptation period length and titration diet type on apparent ileal phosphorus digestibility and phosphorus retention in growing broilers.
abstract: Two experiments were conducted to examine the effects of different corn titration diets and dietary adaptation period length (DAPL) on intestinal histology, apparent ileal P digestibility (AIPD), and apparent P retention (APR) in Ross × Ross 708 male broilers from 20 to 24 d of age. It was hypothesized that purified ingredients in nutrient-deficient titration diets may affect P availability with varying DAPL. In experiment 1, 1,152 broilers were utilized in a 3 × 3 factorial treatment structure with 3 diets (control, 25% corn titration diet [25CTD], or 75% corn titration diet [75CTD]) and 3 DAPL (0, 24, or 72 h). Experiment 2 was conducted with 576 broilers as a 4 × 3 factorial arrangement with 4 diets (control, 25CTD, 75CTD, or nitrogen-free diet [NFD]) and 3 DAPL (24, 48, or 72 h). All diets contained purified ingredients except for the control diet, which had the same formulation as the common starter and served as a control for DAPL. The NFD diet was fed as a highly purified protein-free diet. Broilers were fed a common diet until 19 d of age and then transferred to experimental diets at 20 d of age. In experiment 1, diet type did not affect (P > 0.05) intestinal histology. However, diet type and DAPL each influenced (P.≤.0.001) diet AIPD. Higher (P.≤.0.001) AIPD was measured for the control diet compared with the 75CDT, and the 25CTD had the lowest AIPD. Following a 24 h DAPL, AIPD was higher (P.≤.0.001) than after a DAPL of 0 or 72 h. In experiment 2, diet type × DAPL interactions (P.≤.0.001) were observed for APR of the control diet, 75CTD, and NFD, but not the 25CTD. Because APR of the control diet was affected by varying DAPL, factors other than differences in diet type may have been responsible for inconsistencies in the measure of P availability. Furthermore, no clear evidence was observed that broilers were able to adapt to P-deficient diets by increasing APR or AIPD. In conclusion, a standard DAPL should be established as a means to reduce variability associated with measuring of feedstuff P availability.
authors.affiliation: Department of Poultry Science, Auburn University, Auburn, AL 36849.
authors.forename: K R
authors.initials: KR
authors.lastname: Perryman
authors.affiliation: Department of Pathobiology, Auburn University College of Veterinary Medicine, Auburn, AL 36849.
authors.forename: R C
authors.initials: RC
authors.lastname: Cattley
authors.affiliation: AB Vista Feed Ingredients, Marlborough, Wiltshire, SN8 4AN, United Kingdom.
authors.forename: H V
authors.initials: HV
authors.lastname: Masey O'Neill
authors.affiliation: AB Vista Feed Ingredients, Marlborough, Wiltshire, SN8 4AN, United Kingdom.
authors.forename: M R
authors.initials: MR
authors.lastname: Bedford
authors.affiliation: Department of Poultry Science, Auburn University, Auburn, AL 36849 WAD0005@auburn.edu.
authors.forename: W A
authors.initials: WA
authors.lastname: Dozier
mesh_terms: D000064:Acclimatization; D000821:Animal Feed / Q000032:analysis; D000824:Animal Nutritional Physiological Phenomena; D000818:Animals; D002645:Chickens / Q000254:growth & development / Q000502:physiology*; D004032:Diet / Q000662:veterinary*; D004063:Digestion / Q000502:physiology*; D007082:Ileum / Q000502:physiology; D008297:Male; D016226:Phosphorus, Dietary / Q000378:metabolism*; D011897:Random Allocation; D013997:Time Factors
chemical_list: D016226:Phosphorus, Dietary
keywords: broilers; digestible phosphorus; retainable phosphorus; semipurified diets