Developing embryos and hatchling poults were sampled (n = 4) at Days 22, 24, 26, and 28 of incubation and at 1, 2, 4, 6, and 8 days after hatching, and selected characteristics of the gastrointestinal tract (GIT) were measured. Body weight increased linearly up to day of hatching and also from 2 to 8 days posthatching. Residual yolk weight decreased rapidly starting on Day 26 of incubation and was nearly depleted by 4 days posthatching. Changes in weight of segments of the GIT nearly paralleled the increase in body weight until day of hatching. Thereafter, weights of the proventriculus, small intestine, and pancreas increased more rapidly than body weight until 6 days after hatching. At this time, change in weight of small intestine and pancreas seemed to parallel that of body weight, whereas proventriculus weight continued to increase more rapidly. Gizzard weight, as a percentage of body weight, increased until Day 4 posthatching and then remained relatively constant through 8 days. Specific activities (SA) of pancreatic amylase, lipase, and trypsin were low until after hatching. Subsequently, amylase SA increased nearly threefold by Day 6. Lipase SA remained nearly constant between Days 1 and 8, and trypsin SA increased only slightly. Total activities of pancreatic enzymes, however, increased substantially after hatching, mainly because of increased pancreas weight. Jejunal maltase SA was high at hatching but decreased markedly by Day 4. This decrease in SA resulted in a notable reduction in total maltase activity of the jejunum despite an increase in jejunum weight.

An experiment was conducted to test the hypothesis that the decline in eggshell quality over time during egg production, and its improvement after molting, paralleled the rate of calcium uptake by the duodenum of the laying hen. In vitro duodenal calcium uptake rate and femur ash (percentage of femur weight) were determined at 37, 45, 51, 58, 68, and 72 wk of age. Percentage shell and shell thickness (millimeters) were determined at 22, 29, 36, 44, 50, 57, and 71 wk of age. Molt was induced at 63 wk of age. Three commercial strains DeKalb XL-Link, ISA/Babcock B-300V, and Hy-Line W-36 were compared. There were no differences in duodenal calcium uptake rate among strains. There was a significant decline (P < .01) in duodenal calcium uptake from 408 pmol/mg tissue per min at 37 wk of age to 329 pmol/mg per min at 58 wk of age. Femur ash decreased (P < .01) from 50.8% at 37 wk of age to 47.6% at 58 wk of age. Percentage shell and shell thickness declined (P < .01) from 9.79% and .403 mm at 22 wk of age to 8.88% and .373 mm at 57 wk of age, respectively. After the induced molt, duodenal calcium uptake increased (P < .01) to 402 pmol/mg tissue per min, and percentage shell and shell thickness increased (P < .01) to 10.23% and .389 mm, respectively. Duodenal calcium uptake increased immediately postmolt, whereas femur ash did not increase until 72 wk of age (P < .01).

The effects of dietary Spirulina platensis on chicken macrophage phagocytic function and nitrite production were examined. Day old broiler (meat-type) chicks were randomly assigned to various pens of electrically heated wire batteries. Dietary treatment groups included a basal diet with no dietary Spirulina added, and three additional groups with 0.5, 1.0 and 2.0% dietary Spirulina. Feed and water were provided for ad libitum consumption from one day of age. Sephadex-elicited macrophages were harvested at 14, 35 and 42 days of age. Phagocytosis assay was performed by co-incubating sheep red blood cells (SRBC) with the adherent macrophage monolayers. For nitrite quantification, macrophage cultures from various dietary treatment groups were stimulated in the presence or absence of 1 microg/mL of Escherichia coli lipopolysaccharide. These culture supernatant fractions were then tested for nitrite levels using the Greiss reagent technique. All Spirulina dietary group macrophages exhibited an enhanced phagocytic activity in terms of overall phagocytic percentage (range = 28 to 39% versus 24 to 25% in the basal group) and the average number of SRBC per phagocytic macrophage (range = 2.2 to 3.6 versus 1.8 to 2.5 in the basal group). This increase was linear with each incremental increase of dietary Spirulina. While LPS-induced nitrite levels in macrophages from basal diet group ranged from 60 to 278 microM over the three developmental ages, these levels in all Spirulina dietary groups were significantly higher (0.5% group range = 198 to 457 microM; 1.0% group range = 161 to 359 microM and 2.0% group range = 204 to 420 microM. These data clearly show that Spirulina platensis feeding upregulates macrophage phagocytic as well as metabolic pathways leading to increased nitric oxide synthase activity. These findings therefore imply that Spirulina platensis may enhance the functions of mononuclear phagocytic system thereby increasing the disease resistance potential in chickens.

A study was undertaken to evaluate the effects of Neoxyval (antimicrobial growth promoter (AGP)), TechnoMos (prebiotic), GalliPro (probiotic) and a mixture of TechnoMos and GalliPro (symbiotic) on growth performance, carcass yield, histomorphology and intestinal bacterial counts in broilers (0 d to 42 d). Two hundred day-old Ross (308) broilers were allocated to five experimental treatments: T1 = control (CONT), T2 = T1 + Neoxyval, T3 = T1 + Gallipro, T4 = T1+ TechnoMos and T5 = T1+ Gallipro+ TechnoMos. The results revealed that birds that received T2, T4 and T3 gained more weight and converted feed more efficiently than those in T1 and T5. Longer ileal villi (492.9 µm) were recorded in birds that received T4 compared with T1 (424.7 µm) and T2 (439.9 µm). Conversely, jejunal villi length and width were not influenced by treatment. T3 eliminated Clostridium perfringens from the ileum, but not from the caecum. Generally, birds that received T3 and T5 performed similar to the AGP group, T2. The results from this study indicated that the probiotic (T3) and prebiotic (T4) used in this trial could serve as alternatives to AGP (T2). Enhancement in the performance of broilers could be explained partially by improvement in intestinal morphology and microbial balance associated with modulation of intestinal microflora and inhibition of pathogens. ______________________________________________________________________________________

The current experiment was conducted to evaluate the effect of stocking density (SD) on the performance and immunity of 1-to 14-d-old broilers. A total of 1836 one-day-old Cobb 500 broilers were housed at four different SD (30, 60, 90 and 120 chicks/m 2 ). Body weight gain (BWG), feed intake (FI) and feed conversion ratio (FCR) were estimated on d 2, 5, 8, 11 and 14. Relative lymphoid organ weights, maternal antibody titers against IBV, IBD and NDV, and stress indicators were estimated on d 3, 6, 9 and 12.The results indicated that age significantly (p<0.001) affected the performance and immunity of broiler chicks. Stocking density significantly (p<0.001) affected the performance and physiological stress indicators of broiler chicks, but not maternal immunity, relative lymphoid organ weights, or blood glucose levels. A significant interaction between age and density was determined for BWG, FI and FCR, and maternal antibody titers against IBD and NDV. The results also indicated that the effects of SD were age-dependent: as SD increased, worse performance, lighter lymphoid organs, and stronger stress responses were observed as broilers aged. It is concluded that the higher the SD during the first two weeks of life, the worse is the performance as broilers age.