A study was conducted in a completely randomized design to evaluate the performance, excreta characteristics, and some blood nitrogen metabolite concentrations of 28-d-old male broilers fed 4 experimental diets in which CP was decreased in a stepwise manner from 23 to 17%. The other 4 diets were formulated to have 19 and 17% CP, in which 2 of them contained an additional 10% of particular essential amino acids (EAA) and 2 were supplemented with Gly and Glu. Ileal digestible quantities of all EAA were almost equal in the diets, and total amount of each EAA was maintained at or above NRC requirements. Decreasing dietary CP below 19% depressed performance and appetite and increased fat deposition in the whole body and abdominal cavity significantly. Adding the Gly and Glu mixtures to low-CP diets improved performance and decreased fat deposition. Uric acid, moisture, and acidity of excreta were decreased by reduction of dietary CP; excretory ammonia level was increased in 17% CP diets. Blood ammonia level was increased and plasma uric acid was decreased with reduction of CP to 17%. Supplementing Gly and Glu increased plasma and excretory uric acid level in spite of decreasing blood ammonia concentration. The aminostatic hypothesis cannot explain the sharp reduction in appetite in this experiment, because alteration of dietary CP had no significant influence on most plasma free amino acid levels. Therefore, reduction of CP to 19% not only does not impair performance but also decrease nitrogen, ammonia, and pH of excreta that may improve upon litter and air quality. Adding large amounts of crystalline EAA to diets with low intact CP increased blood and excretory ammonia concentration, which due to its negative effects on tissue metabolism may be the main cause of retarded growth and appetite in decreased CP diets below 19%.

In this study, 332 lactic acid bacteria of broiler gut origin were investigated as putative probiotic candidates. Sixty-two bacteria showed the highest aggregation while showing antibacterial effects against Salmonella Enteritidis, Salmonella Typhimurium, and Escherichia coli O78:K80. Enzymatic activities of the selected bacteria were examined. No lipase activity was detected, but all of them showed almost similar proteolytic activities. However, they had different amylase and phytase activities. Four of the 62 bacterial strains were selected as a result of aggregation and amylase tests. They were chosen for the following attributes: high cell surface hydrophobicity, co-aggregation, and resistance to bile salts and also acidic conditions. Finally, Lactobacillus crispatus was selected as a source of potential probiotic because of its predominant characteristics in comparison to the other isolated strains from the gastrointestinal tract of chickens. This study has provided a good arrangement of rapid methods for screening a high number of bacteria: a series of beneficial tests that are used together for the first time on chickens, and not any other animals.

Two experiments were conducted to evaluate the effects of using black cumin seeds (BCS), Artemisia leaves (AL), and Camellia L. plant extract (CLE) in the diets of broiler chicks. Experiment 1 was conducted as a completely randomized design in a factorial arrangement (2 × 2) with 8 replicates of 4 chicks in each battery cage. Factors included 2 levels of BCS and AL (0 and 1%). Experiment 2 was conducted as a completely randomized design with 4 treatments (control, 0.3 and 0.5 g/kg of CLE, and 0.5 g/kg of mannanoligosaccharide) of 8 replicates and 4 chicks in each. Body weight and cumulative feed intake were measured at 21, 35, and 42 d of age. Antibody response against SRBC was measured on d 28 and 42. Blood characteristics, relative weight and length of different parts of the carcass, gastrointestinal pH, villi length, and crypt depth were measured at 42 d of age. Artemisia addition did not affect BW and feed conversion ratio (FCR) but decreased feed intake significantly up to 21 d of age (P ≤ 0.01). Black cumin significantly increased BW (P ≤ 0.05) at 21 and 42 d of age and decreased FCR throughout the experimental period (P ≤ 0.01). Artemisia significantly increased monocytes but had no effect on gastrointestinal pH, antibody response, and relative weight and length of different parts of the carcass. Black cumin increased red blood cells, hematocrit, hemoglobin, gizzard relative weight, and pH but decreased antibody response and monocytes percentage (P ≤ 0.01). Artemisia did not affect plasma lipid profile but decreased coliform and Escherichia coli populations of ceca significantly (P ≤ 0.01 and P ≤ 0.05, respectively). Addition of 0.5 g/kg of CLE decreased BW, feed intake, and FCR throughout the experiment (P ≤ 0.01). Camellia increased gizzard and proventriculus pH, villi length, and crypt depth (P ≤ 0.01) but decreased primary antibody response, total white blood cell count, and cholesterol concentration (P ≤ 0.05). The results of this experiment showed that using BCS alone or mixed with AL improved broiler health and performance but CLE negatively affected broiler BW and feed intake and is not a good alternative to commercial mannanoligosaccharide.

An experiment was conducted to study the effects of inclusion of a wheat cultivar (high in nonstarch polysaccharides) and xylanase supplementation of the diet on productive performance, pH of the gastrointestinal tract, nutrient retention, and intestinal enzyme activity of Hy-Line W-36 laying hens from 25 to 47 wk of age. The experiment was completely randomized with 8 treatments arranged factorially with 4 levels of wheat (0, 23, 46, and 69%) that corresponded to a dietary arabinoxylan content of 3.0, 3.3, 3.6, and 3.9%, with or without xylanase supplementation. Each treatment was replicated 5 times. For the entire experimental period, egg weight (P < 0.05) and egg mass (P < 0.01) were reduced and the feed conversion ratio was hindered (P < 0.05) with increased levels of wheat in the diet, but ADFI and egg production were not affected. Xylanase supplementation improved egg production (P < 0.05), egg mass (P < 0.01), and the feed conversion ratio (P < 0.01). Diet did not affect egg quality at any age, except for shell thickness at 47 wk that was improved with xylanase supplementation (P < 0.05). Digesta pH of the different organs of the gastrointestinal tract was not affected by wheat inclusion or xylanase supplementation. Ileal viscosity increased (P < 0.001) with wheat inclusion and decreased (P < 0.001) with xylanase supplementation at all ages. Fat digestibility (P < 0.001) decreased with increased levels of wheat but AME(n) content of the diets (P < 0.05) and nitrogen retention were not affected. Wheat inclusion increased (P < 0.001) amylase (33 wk), lipase (33 wk), and aminopeptidase (47 wk) activity in the duodenum as well as lipase activity in the jejunum at 47 wk of age. However, xylanase supplementation did not affect the activity of any of the enzymes studied. It is concluded that most of the negative effects of wheat inclusion in the diet were reduced or even disappeared with xylanase supplementation. Wheat with a high nonstarch polysaccharide content (Pishtaz cultivar) can be used at levels of up to 69% in laying-hen diets without negatively affecting bird performance, provided that feeds are supplemented with xylanase.

We investigated the effect of selection for 4-wk feed conversion ratio (FCR) on genetic improvement of FCR, BW, weight gain (WG), feed intake (FI), and residual FI (RFI) in Japanese quail. The F line was selected for reduced FCR and the C line was maintained as a randombred control. In each generation, 35 sires and 70 dams were used as parents for the next generation. Three generations of selection were performed. Realized heritability for FCR was calculated as the ratio of cumulative selection response to the cumulative selection differential, and additionally, genetic response was quantified as the difference between the means of selection and control lines. The results showed that realized heritability for FCR after 3 generations of selection was 0.67. The mean FCR in F line and C line in the last generation was 2.13 and 2.61, respectively. This is 18.4% cumulative genetic improvement, or 6.1% improvement per generation. In the last generation, the means of F and C lines were 193 and 166 g for BW at age 28 d (16.4% total increase, or 5.5% per generation), 184 and 158 g for WG (17.2% total higher gain and 5.7% per generation), 393 and 413 g for FI (4.9% total higher consumption and 1.6% per generation), and -24.5 and 10.2 for RFI (-34.7 g of cumulative gain; -11.6 g per generation), respectively. These results show that selection to decrease FCR increases BW and WG and decreases FI and RFI as a correlated response.