2016 SOUTHERN POULTRY SCIENTIFIC SYMPOSIUM

Examining the effect of dietary electrolyte balance, energy source, and length of feeding of nitrogen-free diets on ileal endogenous amino acid losses in broilers
S. Adedokun, A. Pescatore, A. Cantor, J. Jacob, M. Ford, T. Ao, A. Helmbrecht
The effect of dietary electrolyte balance (DEB), source of energy (ES), and length of feeding of nitrogen-free diets (NFD) on ileal endogenous amino acid losses (IEAAL) in mg/kg DMI and mg/kg of digesta/g of feed intake (FI) was evaluated in broiler chickens. A total of 1,080 chicks were used with 15 replicate cages of 6 chicks/replicate. Treatments (12) consisted of four NFD, consisting of 2 levels of DEB (106 and 208 mEqv/kg) and 2 sources of energy (corn starch, CS and dextrose, DX), and 3 sampling time-points (72 h- d 16-19; 120 h - d 16-21; and 72 h - d 18-21). All birds had access to feed and water on an ad libitum basis. Data were analyzed using the GLM procedure of SAS appropriate for a completely randomized design for a factorial arrangement of treatments. With the exception of Lys, Thr, Cys, Pro, and Ser, high DEB resulted in higher (P<0.05) total IEAAL (6,983 vs. 6,440 mg/kg DMI and 23.9 vs. 20.7 mg/kg of digest/g of FI). Dietary DX resulted in higher (P<0.05) total IEAAL (7,041 vs. 6,383 mg/kg DMI and 25.8 vs. 18.9 g/kg of digesta/g of FI) except for His and Thr. Total IEAAL for all AA were greater (P<0.05) for the birds fed the NFD from d 16 -19 or d 16-21 compared with birds fed the NFD from d 18-21 (7,489 or 7,228 vs. 5,418 mg/kg DMI). There was no difference in IEAAF for the birds fed the experimental diets from d 16 to 21 compared with d 18 to 21 (16.5 vs. 19.0 g/kg FI) but lower (P<0.05) compared with birds that were fed from d 16 to 19 (17.7 vs. 31.5, g/kg FI). Three-way interactions were observed (P<0.05) for N, total AA, and all the AA except for Trp. Birds on DX-based NFD containing high DEB that was fed from d 16-19 had the highest (P<0.05) total IEAAL (11,080 mg/kg DMI or 49.2 mg/kg of digesta/g of FI. It is concluded that high DEB and DX in the diet and shorter exposure to the DX-based NFD diets could increase IEAAL.

Energy source and not dietary electrolyte balance influenced ileal endogenous amino acid losses in 21 d-old broilers fed nitrogen-free diets
S. Adedokun, A. Pescatore, A. Cantor, M. Ford, J. Jacob, T. Ao, A. Helmbrecht
The effect of dietary electrolyte balance (DEB) and sources of energy on ileal endogenous amino acid (EAA) losses was evaluated in 21 d-old broilers. A total of 360 chicks were assigned to 4 experimental treatments on d 16 with 6 birds/cage and 15 replicate cages/treatment. Treatments consisted of four nitrogen-free diets (NFD) with 2 levels of DEB (106 and 208 mEqv/kg) and 2 sources of energy (corn starch and dextrose). All birds had access to feed and water on an ad libitum basis throughout the experimental period. Ileal EAA losses in mg/kg DMI and in g/kg of digesta/g of feed intake (FI) during the 5-d feeding period (d 16-21) were calculated. Data were analyzed using the GLM procedure of SAS appropriate for a completely randomized design for a factorial arrangement of treatments (2 x 2). For both methods of estimation (mg/kg DMI and g/kg of digesta/g of FI), there were no interactions between DEB and source of energy. Low DEB (106) resulted in higher (P<0.05) ileal endogenous Arg (304 vs. 251), Lys (432 vs. 348), Glu (873 vs. 730), Ser (460 vs. 387) losses in mg/kg DMI and lower endogenous Trp loss (59 vs. 74 mg/kg DMI). Seven AA (Ile, Leu, Met, Phe, Ala, Gly, and Tyr) showed a tendency (P<0.1) for higher endogenous losses with low DEB. When estimated in g/kg of digesta/g of FI, low DEB resulted in higher (P < 0.05) endogenous Lys (0.970 vs. 0.829) and lower (P<0.05) endogenous Trp (0.127 vs. 0.171) losses. All the indispensable AA showed increased (P<0.05) endogenous losses (mg/kg DMI) when dextrose was the only source of energy in the diet except Trp (lower, P<0.05), His (no difference), and Thr (tendency for increased loss with corn starch; P=0.058). For the dispensable AA, only Ala (343 vs. 281 mg/kg DMI) and Asp (647 vs. 509 mg/kg DMI) showed increased (P<0.05) ileal endogenous losses with dextrose. With the exception of Trp (no effect), dextrose as the only source of energy in the diets resulted in higher (P<0.05) ileal EAA losses for all the AA, nitrogen (4.15 vs. 3.12) and total AA (18.7 vs. 14.2) in g/kg of digesta/g of FI. Results from this study showed that dextrose as the sole source of dietary energy had greater effect on ileal EAA losses in 21 d-old broilers fed NFD when compared with DEB level.