. W. 2010. Effect of dietary citric acid, flavomycin and their combination on the performance, tibia ash and immune status of broiler. Can. J. Anim. Sci. 90: 57Á63. The goal of this research was to investigate the effect of citric acid (CA), the antibiotic growth promoter flavomycin (FL) and their combination on the growth performance, tibia ash and immune status of broilers. One hundred and sixty straight run day-old broiler chicks (Hubbard Classic) were randomly distributed into four dietary groups, with four replicate cages having 10 birds in each. Standard cornÁsoybean-based basal starter diet was given to control birds. Diets for other groups were further fortified by 0.5% CA, 0.001% FL and their combination (0.5% CA plus 0.001% FL). On day 35, CA and its combination (CA'FL) group had 17 and 12% increase in live weight compared with control, respectively (PB0.05). Total live weight on day 35 was 1141, 1337, 1169, and 1275 g bird Á1 in different groups, respectively (PB0.05). Cumulative feed intake was higher (P B0.05) in CA and its combination (CA'FL) compared with the control and FL groups on day 28. Supplementation with CA improved (P0.05) feed conversion ratio [FCR; feed intake (kg):weight gain (kg)] compared with FL and its combination (CA'FL). Carcass yield was increased (P0.05) due to the addition of CA and its combination (CA'FL). Tibia ash content in the CA group (59.0) was higher (PB0.05) than in the control (53.6%), FL (53.1%) and their combination (57.1%). The lymphocyte cells associated with immunity in the lymphoid organs (caecal tonsil, bursa Fabricius and ileum) were more densely populated, suggesting an increased level of innate immunity in the CA group. Overall mortality was low (1.25%), and there were no treatment-related effects on mortality. Citric acid reduced the pH of formulated feeds, but mild reduction was found in the pH of the faeces. Dietary supplementation of 0.5% CA increase weight gain, feed intake, tibia ash deposition and non-specific immunity (PB0.05) as well as feed efficiency and carcass yield (P0.05) of broilers. Citric acid has potential as a growth promoter to replace the antibiotic growth promoter FL. . Les oiseaux du groupe AC avaient plus (PB0,05) de cendres dans le tibia (59,0%) que ceux du groupe te´moin (53,6%), du groupe FL (53,1%) et du groupe prenant le me´lange (57,1%). Les organes lymphoı¨des (gros intestin, amygdales, bourses de Fabricius et ile´on) renfermaient plus de lymphocytes associe´s au pouvoir immunitaire, ce qui laisse croire que les oiseaux du groupe CA jouissaient d'une meilleure immunite´inne´e. Dans l'ensemble, le taux de mortalite´e´tait faible (1,25 %) et les traitements n'ont eu aucune incidence sur la mortalite´. L'acide citrique re´duit le pH de la ration, mais celui des fe`ces ne connaıˆt qu'une le´ge`re baisse. L'addition de 0,5 % d'AC aux aliments

Salt accumulation in cultivated and cultivable rice (Oryza sativa L.) and other croplands poses a serious threat to irrigated agriculture. Development of cultivars with high tolerance to salinity, and methodology to monitor and rapidly screen for salt tolerance may ameliorate the problem to a considerable extent. Because of the involvement of ethylene in growth responses under stress, its potential as an indicator of salt tolerance in rice in laboratory tests was investigated. Little ethylene was detected in rice seeds in the presence or absence of 0.1 M NaCl with up to 6 days of soaking. When 1‐aminocyclopropane‐1‐carboxylic acid (ACC) was used alone or in combination with salt, ethylene production began on the third day of soaking, reached a maximum by 4 to 5 days, and then declined. A parallel increase in ethylene production and shoot growth occurred in the presence or absence of salt with an increase in ACC concentration, reaching a maximum at 1 to 2 mM; at 5 to 50 mM both processes were inhibited. The ACC‐derived ethylene production and shoot growth were inhibited to varying extent in the rice genotypes by the addition of 0.1 M NaCl. At the saturating dose of ACC (2 mM), ethylene production and shoot growth appeared to depend on the activity of the ethylene forming enzyme (EFE) since Co2+, and not aminoethoxyvinylglycine (AVG), inhibited both processes. The capacity of rice to produce ACC‐dependent ethylene was a cultivar trait and correlated well (r = 0.91) with salt tolerance at the seedling stage. The data indicate that ethylene may serve as a biochemical marker for mass screening of large breeding populations of rice for salinity tolerance at the seedling establishment phase.

Enhanced ethylene‐producing capacity of young seedlings of floating and deepwater rice (Oryza sativa L.) during submergence has been related to increased seedling elongation via leaf sheath/leaf blade. In this study we present evidence for modulation of elongation by hormones. Floating rice cuitivars ‘TCA 4’, ‘TCA 177’, and ‘TCA 212’ were used. Effects of various hormones and chemicals on elongation and ethylene‐producing capacity were determined during complete submergence of seedlings in 122‐ ✕ 6‐cm glass cylinders. Enhancement in ethylene‐producing capacity by submergence was completely suppressed by 0.05 mM aminoethoxyvinylglycine (AVG), indicating that the enhancement depended on the synthesis of 1‐ aminocyclopropane‐l‐carboxylic acid (ACC). Submergence‐induced elongation was partially inhibited by 0.05 mM AVG in 24 h and reversed to some extent by 0.1 mM ACC or 0.05 mM ethephon (2‐chlorethane phosphonic acid). Increase in ethylene‐producing capacity during submergence was also inhibited by 1 mM Co2+, which had no effect on seedling elongation. Gibberellin (GA) biosynthesis inhibitor, tetcyclacis [5‐(4‐chlorophenyl)‐3,4,5,9,10‐pentaazatetracyclo‐5,4,102.6, 08.11 dodeca‐3, 9‐diene] (TCY), strongly inhibited the increase in seedling elongation of TCA 177 without affecting ethylene‐ producing capacity. The effect of TCY on elongation was reversed by 0.1 mM GA4+7 (gibberellin A4 + A7). Abscisic acid (ABA) inhibited the ethylene‐producing capacity and the effect was reversed by kinetin. Application of GA4+7 plus kinetin caused a 60% reversal of ABA inhibited elongation. Nonsubmerged floating (TCA 177) and deepwater (‘BR 118‐3B‐17’) rice elongated to a greater extent than the nonelongating types when sprayed with 0.1 mM GA4+7. Thus, GA may influence elongation more directly than other hormones.