No abstract

The effect of lipopolysaccharide (LPS) on the expression of proinflammatory cytokines, interleukin (IL)-1beta, IL-6, and IL-12 in broiler chick thrombocytes was investigated. At 4 wk of age, blood samples were collected, and isolated thrombocytes were incubated with LPS for 1 h. Ribonucleic acid was extracted from the cells to examine the expression of the proinflammatory cytokines using real-time reverse transcription PCR. It was found that expressions of IL-1beta, IL-6, and IL-12 in thrombocytes were unaffected by diets containing corticosterone and vitamin C fed to chicks. However, LPS exposure did increase the expressions of these cytokines. The fact that thrombocytes are so abundant and can be stimulated by LPS makes them primary effector cells in innate host defenses against bacterial infections in chickens.

Summary The objective of this study was to adapt an assay to measure L‐gulonolactone oxidase (GLO) activity, the final step in ascorbate synthesis, in chickens and use the procedure to study the effect of gender, age, and food deprivation. To adapt a procedure used for mammalian tissues the kinetic constants were estimated using chicken kidney and assay conditions optimized in terms of storage of tissue and homogeneity of distribution. A series of experiments were conducted using the standardized assay with individual animals as the experimental unit. Gender differences were detected only in mature birds with male chickens having lower GLO activity than females. Time‐course changes in GLO activity in immature chicks were best characterized by a segmented response function consisting of a parabola joined to a straight line. The maximum value was estimated to occur at 13 days and from day 16 declined linearly. The functional relationship did not provide evidence of an early lag period or a peak at 4 weeks in immature chickens. Food deprivation in matched groups of birds demonstrated the effect of food on GLO activity in chickens. Food and water deprivation for 12 h and food deprivation for 24 h had no significant effect on GLO activity. Food deprivation for 48 h caused a significant decrease in GLO activity and it was not further depressed by deprivation for 72 h. Initial GLO activity was restored within 24 h of repletion. The results clearly demonstrated that gender, age, and starvation are determinants of ascorbate synthesis in chickens.

An experiment was conducted with broiler chicks to determine the effect of 0, 5, 10, and 20% supplemental poultry fat and age on gastrointestinal transit time (GTT) and the effect of supplemental fat on fat utilization and growth. Mean GTT, measured with chromic oxide or ferric oxide, was not affected by supplemental fat. There was a curvilinear relationship (rising ogive) between mean GTT and age. It increased from an estimated lower plateau of 170 min to an upper plateau of 211 min with the inflexion point at 3.23 wk. At 6 wk of age, birds receiving supplemental fat consumed more energy and were heavier and more efficient. Total lipid digestibility increased with supplemental poultry fat but digestibility of poultry fat was not altered. The AME of poultry fat ranged from 8.1 to 8.4 kcal/g at 5 to 20% inclusion in the diet.

No abstract