| Abstract: |
The objectives of this study was to investigate quantitatively describe the effect of dietary levels of protein and total sulfur amino acids on the performance and egg quality as well as digestibility of nutrients in the diet, environmental pollution by nitrogen, some biochemical blood parameter and chemical composition of the egg for Lohmann Brown laying hens.A 3×3 factorial treatment arrangement was performed to study the effect of three levels of crude protein (16, 18 and 20%) and three levels of total sulfur amino acids (0.67, 0.72 and 0.77%). A total number of 180 Lohmann Brown hen 18-wk-old at were randomly divided into 9 experimental groups 5 replicates each. Hens of all experimental groups had nearly the same initial average weight.The results obtained showed that Egg number and egg mass were increased (P<0.01) for hens fed diets of 20 and 18% CP versus that of 16% protein through the period from 26-30 wks of age. There were no significant effects of dietary protein levels on globulin, uric acid and creatine, while total protein, albumen and urea of hens fed the high and moderate protein diet were significantly greater than those of hens fed the low-protein diet from 30-34 wks. Feed efficiency and protein utilization values were improved with 0.67 and 0.72% TSAA during 26- 30 wks of age. Whilst, feed intake and protein utilisation at the other studied ages were not significantly affected by TSAA levels. Chemical composition criteria in whole egg (moisture, egg solids, egg protein, ether extract, nitrogen free extract, organic matter and total minerals) didn’t influenced by TSAA intake in diet of Lohmann hens during 18-34 wk of age. There were no significant effects of dietary protein levels on globulin, A/G ratio, uric acid and creatine, while total protein, albumen and urea of hens fed the high and moderate protein diet were significantly (P<0.05) higher than those of hens fed the low-protein diet at 34 wk.Dry matter (DM), organic matter (OM) and ether extract digestibility (EE) had been significantly (p<0.01) improved by decreasing protein levels. TSAA had significantly (p<0.05 or 0.01) affected nitrogen consumption and nitrogen excreted where 0.72% TSAA recorded the highest values for total amount of nitrogen consumed 3.98 g/d and the nitrogen removed in excreta 0.527 g/d compared with other levels. In conclusion, the best production criteria could be obtained by using 0.72% TSAA. Moreover, dietary level of 20% CP with 0.72%TSAA is recommended for feeding Lohmann hens during the whole experimental period (18-34 wk of age), but from the ecological and healthical aspect reducing of protein in layer diets (16%) with supplementation of essential amino acid (Methionine + cystine) could play a significant role in reducing of nitrogen pollution from poultry manure.
|
|
|