Effects of Supplemental Dietary Phytase and 25-Hydroxycholecalciferol on the Digestive and Reproductive Organ Characteristics of Commercial Layers Inoculated Before or at the Onset of Lay with the F-Strain of Mycoplasma gallisepticum

Performance, serologic and tracheal responses of laying hens exposed to F strain of Mycoplasma gallisepticum

ABSTRACT: The F strain of Mycoplasma gallisepticum (MG-F) protects chickens against mycoplasma infections, in which monitoring is made by serology and histopathology of trachea. This trial used 90 chickens, being 30 unvaccinated (G1 group), 30 eye-drop vaccinated at 8 weeks of age with MG-F (Ceva Animal Health, São Paulo, SP, Brazil) (G2), and 30 immunized at 8 and 11 weeks of age (G3). Samples were obtained from chickens on the 8, 12, 15, 18, 20 and 24th weeks of age for the enzyme-linked immunosorbent assay (ELISA) test. Tracheal fragments were collected after necropsies on the 15 and 24th weeks of age. Up to 12 weeks, the ELISA reactions in optical density (OD) were 0.165 (G1), 0.151 (G2) and 0.151(G3), all below 0.20 and with no significant difference among groups (p > 0.05). After the 15th week, the ELISA reactions rose, yielding the following group averages by collecting dates: G1 (0.18, 0.19, 0.18, and 0.16), G2 (0.36, 0.49, 0.47, and 0.44) and G3 (0.41, 0.52, 0.59, 0.60), being the means in G2 and G3 not significantly different between than, but significantly different from G1. The initial weight (592.71, 621.33, and 594.40), the final weight (1,932.58, 1,987.59, and 1,875.20) and the weekly weight gain (11.65, 11.90, and 11.14) were not significantly different among groups. At necropsy the gross tracheal score means by group and dates were: 15th week (0.25, 0.61, and 0.54) and 24th week (0.54, 0.58, and 0.67), being these difference not significantly (p > 0.05). On microscopy, the tracheal score averages by groups G1, G2 and G3, respectively, were: 15th week (0.25, 0.32, and 0.47) and 24th week (0.07, 0.75, and 0.08). G2 yielded higher score average than G1 and G3 on the 24th week. Higher tracheal changes for G2 and G3 as compared to G1 could be ascribed to MG-F infection. There were no evident prejudicial effects on live weight, weight gain and tissue changes by applying one or two vaccination doses.

Influence of supplemental dietary poultry fat, phytase, and 25-hydroxycholecalciferol on the egg characteristics of commercial layers inoculated before or at the onset of lay with F-strain Mycoplasma gallisepticum

The effects of supplemental dietary poultry fat (PF), phytase (PHY), and 25-hydroxycholecalciferol (D3) on the egg characteristics of commercial layers inoculated with F-strain Mycoplasma gallisepticum (FMG) were investigated in 2 trials. Sham and FMG inoculations were administered at 12 (before lay) and 22 (onset of lay) wk and 4 dietary treatments [basal control diet (BCD); BCD with 0.75% supplemental PF; BCD with 1.50% supplemental PF; BCD with 1.50% supplemental PF, 0.013% PHY, and 0.025% D3] were initiated at 20 wk of age. Percentages of albumen, yolk, and eggshell weights; yolk:albumen ratio; yolk moisture and lipid concentrations; and eggshell weight per unit of surface area were determined at 24, 34, 44, 50, and 58 wk of age. Inoculation with FMG reduced yolk lipid concentration at wk 24 and increased yolk moisture concentration at wk 58. In birds inoculated on wk 22, percentage of yolk weight was lower in those inoculated with FMG compared with those that were sham-inoculated. Yolk:albumen ratio was lower in birds that were FMG-inoculated at 22 wk of age compared with those that were sham-inoculated at the same age or that were FMG-inoculated at 12 wk of age. Percentage of yolk weight was greater in birds inoculated at wk 22 and fed the BCD with 1.50% supplemental PF treatment compared with those inoculated at wk 22 and fed the BCD or BCD with 1.50% supplemental PF, 0.013% PHY, and 0.025% D3 treatments and compared with birds inoculated at wk 12 and fed the BCD with 0.75% supplemental PF treatment. In conclusion, inoculation with FMG before or at the onset of lay caused a decrease in yolk lipid content early in lay but an increase in yolk moisture late in lay, and FMG reduced percentage of yolk weight in birds inoculated on wk 22. Furthermore, when used in combination with added 1.50% PF in birds inoculated on wk 22, supplementary PHY and D3 prevented an increase in percentage of yolk weight that occurred in response to diets supplemented only with 1.50% PF.

Influence of supplemental dietary poultry fat, phytase, and 25-hydroxycholecalciferol on the performance of commercial layers inoculated before or at the onset of lay with F-strain Mycoplasma gallisepticum

The effects of 2 levels of supplemental dietary poultry fat (PF) and the combination of PF, phytase (PHY), and 25-hydroxycholecalciferol (D(3)) on the performance of commercial layers inoculated with F-strain Mycoplasma gallisepticum (FMG) were investigated in 2 trials. Sham and FMG inoculations were administered at 12 (before lay) and 22 (early in lay) wk and dietary treatments [basal control diet (BCD), BCD with 0.75% supplemental PF, BCD with 1.50% supplemental PF, and BCD with 1.50% supplemental PF, 0.013% PHY, and 0.025% D(3)] were initiated at 20 wk of age. Hen BW, egg weight, and egg production (EP) were determined every 4 wk between 24 and 58 wk of age. Feed consumption (FC) and feed conversion were determined in 4-wk intervals beginning on wk 25 and ending on wk 58, and total mortality and mean EP were determined over the entire 24 to 58-wk period. The addition of 0.75 and 1.50% PF increased BW at wk 48 and 58, respectively, and supplemental PF at the 1.50% level increased the BW of hens that had been inoculated (sham or FMG) on wk 22 and reduced the FC of hens inoculated on wk 12. Feed conversion was decreased in the 25 to 28- and 57 to 58-wk age periods and increased in the 45 to 48-wk age periods by an FMG inoculation. In birds inoculated at 22 wk of age, FMG increased egg weight. Although EP was reduced at wk 24 and was increased at wk 58 by FMG, total EP was not affected. In conclusion, an inoculation of FMG at either 12 or 22 wk of age can result in a relative shift in EP from the early to late stage of lay without affecting total EP, and although the BW and FC responses of hens to added dietary PF were influenced by their age and the age of inoculation, use of the supplemental combination of PHY and D(3) had no additional effect on performance when provided in conjunction with 1.50% PF.

Effects of time-specific F-strain Mycoplasma gallisepticum inoculation overlays on prelay ts-11-strain M. gallisepticum vaccination on digestive and reproductive organ characteristics of commercial egg-laying hens

Two trials were conducted to determine the effects of a prelay ts-11-strain Mycoplasma gallisepticum (ts-11MG) vaccination alone or in conjunction with F-strain M. gallisepticum (FMG) inoculation overlays at 2 different age periods during lay on the digestive and reproductive organ characteristics of commercial egg-laying hens. In each trial, the following 4 treatments were utilized: sham vaccination at 10 wk of age, ts-11MG vaccination at 10 wk of age, ts-11MG at 10 wk of age overlaid by FMG inoculation at 22 wk of age, and ts-11MG at 10 wk of age overlaid by FMG at 45 wk of age. Necropsies were performed at the end of both trials (58 wk of age), using 2 birds from each of 4 replicate units per treatment, to observe treatment effects on the following parameters: liver weight, liver lipid and moisture concentrations, incidence of fatty liver hemorrhagic syndrome, ovary weight, number of mature ovarian follicles, and the total and segmental weights, lengths, and histologies of the oviduct and small intestine. Treatments affected only vaginal length as a percentage of total oviduct length. Vaginas were relatively longer in hens that had only been vaccinated with ts-11MG at 10 wk in comparison to all the other treatment groups, including controls. Except for relative vaginal length, the digestive and reproductive organs of layers were not influenced by the ts-11MG and FMG treatment regimens imposed in this study. These results confirm that when coupled with FMG inoculations during lay, prelay ts-11MG vaccinations may be a practical substitute for prelay FMG inoculations for providing continual protection against field-strain M. gallisepticum infections in layers.

Effects of supplemental dietary phytase and 25-hydroxycholecalciferol on the performance characteristics of commercial layers inoculated before or at the onset of lay with the F-strain of Mycoplasma gallisepticum

The effects of dietary supplementation with phytase and 25-hydroxycholecalciferol on the performance characteristics of commercial layers that were inoculated prelay (12 wk of age) or at the onset of lay (22 wk of age) with F-strain Mycoplasma gallisepticum were assessed. Experimental layer diets, which included a basal control diet or the same diet supplemented with 0.025% phytase and 25-hydroxycholecalciferol, were fed from 20 through 58 wk of age. Weekly and total egg production were determined from 22 through 58 wk, and egg weight and various internal egg and eggshell quality characteristics were examined at 34, 50, and 58 wk of age. F-strain M. gallisepticum inoculation decreased egg production at the beginning of lay (wk 22 and 23) but increased post-peak lay at wk 45. However, there were no treatment effects of any kind on total egg production, egg weight, or any of the internal egg and eggshell characteristics examined during lay. In conclusion, dietary supplementation with phytase and 25-hydroxycholecalciferol did not affect layer performance or interact with the effects of F-strain M. gallisepticum inoculation; however, F-strain M. gallisepticum inoculation resulted in a shift in egg production from wk 22 to 45 without having an overall effect on total egg production.