Standardized ileal digestible amino acid and metabolizable energy content of wheat from different origins and the effect of exogenous xylanase on their determination in broilers

Abstract

This study was conducted to determine the standardized ileal digestible amino acids ( SID AA ) and nitrogen-corrected apparent metabolizable energy ( AMEn ) contents of 6 wheats from different origins in China and incidentally to investigate the effects of exogenous xylanase addition on SID AA and AMEn determination in broiler chicks. A total of 480 chicks were divided into 48 cages of 10 birds each balanced for body weight and fed 8 types of diets in a completely randomized design (6 replicated cages per diet) from 21 to 26 d of age. The individual wheat constituted the only source of crude protein in a semi-purified experimental diet. A nitrogen-free diet was designed to estimate basal endogenous AA loss and determine the SID AA. Titanium oxide (0.3%) was used as an indigestibility marker, and nutrient digestibility and retention were determined by the substitution method. From day 24 to 26, excreta samples were collected for AMEn determination. On day 26, the birds were euthanized, and ileum contents were obtained for AA digestibility determination. Wheat from Gansu had greater ( P < 0.05) SID AA contents except Lys, Thr, Phe, and Cys, with a higher ( P < 0.001) AMEn (11.83 MJ/kg) than the other wheats. The SID content of mean indispensable amino acids and dispensable amino acids were 87.35% and 88.17%, respectively, and the average AMEn value of 6 wheats was 11.14 MJ/kg. Compared with the diet without xylanase, the added xylanase resulted in higher ( P < 0.05) SID contents of Met, Lys, Trp, Arg, Ile, Leu, Val, Gly, Asp, Glu, Pro, and Ala; the SID AA values were raised by 1.96% (mean of all AA); and the AMEn content was significantly increased (+0.87 MJ/kg) ( P < 0.05). In conclusion, origins of wheats have significant effects on SID AA and AMEn values which were positively correlated with crude protein content of wheat; exogenous xylanase addition to a wheat-based poultry diet could significantly improve SID AA and AMEn contents for broilers.

Comparison of endogenous amino acid losses in broilers when offered nitrogen-free diets with differing ratios of dextrose to corn starch

“…Nitrogen-free diets (NFD) are traditionally used in monogastric animals to calculate SID, where the IEAAs losses are determined by measuring AA excretion in the ileal digesta 5 . Corn starch and dextrose are the main components of the NFD (approximately 80% of NFD), but the ratio of dextrose to corn starch (D/CS) varies in literature (0.21–3.79) 6 – 9 , which may, in turn, affect the flow of IEAAs. Kong et al 10 identified that total IEAAs were significantly higher when dextrose was used as a sole source of energy in NFD than corn starch (17,544 vs. 12,779 mg/kg of dry matter intake).…”

Age-dependent response to fasting during assessment of metabolizable energy and total tract digestibility in chicken

“…For the determination of ME, the ad libitum feeding method is becoming increasingly popular compared to the labor-intensive and time-consuming method of force-feeding. However, there is a lack of consensus on fasting duration ( Lu et al., 2020 ; Yang et al., 2020 ), which necessitates investigating a new fasting procedure in ME assays.…”

Comparative Study of Endogenous Ileal Amino Acid Flow and Digestive Physiology to Nitrogen-Free Diets with Differing Ratios of Dextrose to Corn Starch in Broiler Chickens

“…In monogastric animals fed on nitrogen-free diets (NFD), the IEAAs losses have traditionally been determined by measuring AA excretion in the ileal digesta 4 . Corn starch and dextrose or sucrose are the main components of the NFD (approximately 80% of NFD) [5][6][7][8] . Interestingly, corn starch to dextrose or sucrose ratio varies (0.31 to 9.52) in literature [5][6][7][8] .…”

“…Corn starch and dextrose or sucrose are the main components of the NFD (approximately 80% of NFD) [5][6][7][8] . Interestingly, corn starch to dextrose or sucrose ratio varies (0.31 to 9.52) in literature [5][6][7][8] . This clearly indicates that there is no uni ed standard for the proportion of starch and dextrose in the NFD formula.…”