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At least 595 records · Page 33Linked to original sources
PubMed1999

Effect of phytase enzyme on dietary nitrogen-corrected apparent metabolizable energy and the ileal digestibility of nitrogen and amino acids in broiler chicks.

The effect of phytase on the performance, AMEn, and the ileal digestibility of N and amino acids was investigated in a 15-d trial using day-old male broilers with diets that were low in Ca (0.9% for control and 0.79% for phytase treatment) and available P (AP; 0.45% for control and 0.35% for phytase treatment). The assayed dietary phytase activity of crumble diet was 1,149 phytase unit (FTU)/kg. Chromic oxide was added to the diets to estimate ileal digestibility of N and amino acid. Excreta were collected from Day 12 to 15 to estimate AMEn. Weight gain, feed intake, and feed:gain of chicks fed phytase using diets with low Ca and AP were comparable with those observed for chicks fed more normal levels of Ca and AP. The diet with supplemental phytase had a higher AMEn (P< or =0.01) compared with the control diet. Chicks fed phytase had higher digestibilities for Val, Ile, nonessential amino acids (P< or =0.05), and total amino acids (P< or =0.01).

6-Phytase↗
PubMed2006

Estimation of nitrogen maintenance requirements and potential for nitrogen deposition in fast-growing chickens depending on age and sex.

Experiments were conducted to estimate daily N maintenance requirements (NMR) and the genetic potential for daily N deposition (ND(max)T) in fast-growing chickens depending on age and sex. In N-balance studies, 144 male and 144 female chickens (Cobb 500) were utilized in 4 consecutive age periods (I: 10 to 25 d; II: 30 to 45 d; III: 50 to 65 d; and IV: 70 to 85 d). The experimental diets contained high-protein soybean meal and crystalline amino acids as protein sources and 6 graded levels of protein supply (N1 = 6.6%; N2 = 13.0%; N3 = 19.6%; N4 = 25.1%; N5 = 31.8%; and N6 = 37.6% CP in DM). The connection between N intake and total N excretion was fitted for NMR determination by an exponential function. The average NMR value (252 mg of N/BW(kg)0.67 per d) was applied for further calculation of ND(max)T as the threshold value of the function between N intake and daily N balance. For estimating the threshold value, the principle of the Levenberg-Marquardt algorithm within the SPSS program (Version 11.5) was applied. As a theoretical maximum for ND(max)T, 3,592, 2,723, 1,702, and 1,386 mg of N/BW(kg)0.67 per d for male and 3,452, 2,604, 1,501, and 1,286 mg of N/BW(kg)0.67 per d for female fast-growing chickens (corresponding to age periods I to IV) were obtained. The determined model parameters were the precondition for modeling of the amino acid requirement based on an exponential N-utilization model and depended on performance and dietary amino acid efficiency. This procedure will be further developed and applied in the subsequent paper.

Age Factors↗
PubMed2001

Nitrogen and the Baltic Sea: managing nitrogen in relation to phosphorus.

The Baltic is a large, brackish sea (4 x 10(5) km2) extending from 54N to approximately 66N, with a fourfold larger drainage area (population 8 x 10(7). Surface salinity (2 to 8 PSU) and hence biodiversity is low. In the last century, annual nutrient loads increased to 10(6) metric tons N and 5 x 10(4) ton P. Eutrophication is evident in the N-limited south, where cyanobacteria fix 2 to 4 x 10(5) ton N each summer, Secchi depths have been halved, and O2-deficient bottom areas have spread. Production remains low in the P-limited north. In nutrient-enriched coastal areas, phytoplankton blooms, toxic at times, and filamentous macroalgae reduce amenity values. Loads need to be reduced of both N, to reduce production, and P, to limit N-fixing cyanobacterial blooms. When large N-load reductions have been achieved locally, algal biomass has declined. So far, P loads have been reduced more than N loads. If this continues, a P-limited Baltic proper may result, very different from previous N-limited conditions. Reaching the management goal of halved anthropogenic N and P loads at minimum cost will require better understanding of biogeochemical nutrient cycles, economic evaluation of proposed measures, and improved stakeholder participation.

Environment↗