F-strain Mycoplasma gallisepticum (FMG) may alter reproductive performance in layers through its effects on lipid metabolism. Therefore, the influences of 1.5% supplemental dietary poultry fat (PF) and FMG infection on the early performance of commercial egg-laying hens were determined. Birds were either sham- or FMG-inoculated at 12 wk, and experimental diets were initiated at 20 wk of age. Body weight at 12, 20, and 24 wk, total daily egg mass, feed consumption and feed conversion at 20 and 24 wk, weekly egg weight between 19 and 26 wk, weekly egg production (EP) between 18 and 26 wk, and weekly mortality between 12 and 26 wk of age were determined. Inoculation with FMG reduced EP at 18 and 19 wk of age. Between 20 and 26 wk, FMG reduced EP in birds fed control diets, conversely, PF eliminated differences in EP between sham- and FMG-inoculated birds. Furthermore, at wk 20 and 24, birds consumed less feed when fed PF-supplemented diets than when fed control diets if they were sham-inoculated, but the difference in feed consumption between diets was ameliorated if birds were previously inoculated with FMG. These data demonstrate that the effects of a 12-wk inoculation of FMG on EP and feed consumption through 26 wk of age in commercial egg-laying chickens can be modified by 1.5% supplemental dietary P F. More specifically, PF may alleviate reductions in early EP due to FMG.

Three pen trials were conducted to determine the main effect of alum addition to litter on form of poultry litter P using a 2 x 2 factorial structure of the subunit treatments: diets including high available phosphorus/low phytate corn (HAPC) and phytase (PHYT). Male broilers (1,760 per flock) were grown to 42 d having starter diets with 0.45% available P and grower diets with 0.35% available P. In the first trial, total litter P (tP) was greatest for the yellow dent corn (YDC) diet (12 g/kg) and least for the HAPC and PHYT combination (H&P) diet (6.9 g/kg) with the individual PHYT and HAPC diets falling in between at 9.1 g/kg and 9.4 g/kg tP. Also in the first trial, the litter water-soluble P (wP) was highest for PHYT (2.8 g/kg), least for the HAPC and H&P diets (1.5 g/kg) with the YDC diet falling between (2.2 g/kg). Alum was added to the litter after the first experiment. In the second and third experiments, alum inclusion significantly reduced the wP when compared with the treatments with no alum. In the third trial, the least wP was present in the alum-HAPC treatment. Phytase, YDC, and HAPC diets with no alum litter treatment generated the most wP. Since these diets appear to have little or no difference with respect to quantity of wP, this work suggests that form of litter P generated by alternative diets should be considered as criteria when attempting to reduce P in broiler litter applied to land.

In two trials, the effects of an F-strain Mycoplasma gallisepticum (FMG) inoculation at 12 wk of age on the blood characteristics of commercial Single Combed White Leghorn laying hens were investigated throughout lay. Variables measured in both trials were whole blood hematocrit, plasma protein (PP), and serum cholesterol, triglycerides (ST), and calcium. In both trials, hematocrit at 20 wk of age was significantly increased in birds inoculated with FMG. In trial 1, ST and PP were significantly increased at 22 wk of age by FMG, while ST and PP were significantly decreased in FMG-inoculated birds at wk 54 and 52, respectively. When combined with the establishment of an FMG infection, the initial weeks of egg production become particularly stressful to the bird. Increases in these independent blood parameters between 8 and 10 wk postchallenge are suggestive of compensatory responses in these birds to an FMG challenge. Postpeak decreases in both ST (54 wk) and PP (52 wk) in FMG-infected birds may be the result of a more chronic effect of FMG on lipid and protein synthesis in the liver. These data are the first to suggest that alterations in egg production in response to FMG-infection in commercial layers, as noted in a previous report, may be associated with changes in hematocrit. However, because ST and PP were not affected by FMG in both trials, the responses of these blood parameters to FMG-infection may be inconsistent among flocks.

Two trials were conducted to study the effects of acute (Trial 1) and chronic (Trial 2) mycoplasma infections on differential leukocyte counts in chickens. The trials initially included either 20 (Trial 1) or 40 (Trial 2) 6-wk-old commercial leghorn chickens negative for antibodies to Mycoplasma gallisepticum (MG) and Mycoplasma synoviae (MS). Chickens were inoculated with F strain MG (FMG), MS (WVU 1853), or both. One group of chickens remained uninoculated and served as a negative control for both trials. Chickens were housed in fiberglass isolation units from 6 to 10 wk (Trial 1) or 6 to 70 wk of age (Trial 2). Differential leukocyte counts were examined from 6 to 10 wk (Trial 1) or 66 to 70 wk of age (Trial 2) in all chickens. Also, in Trial 2, packed cell volumes (PCVs) and plasma protein values were examined from 66 to 70 wk of age. In the acute study (Trial 1), differential leukocyte counts revealed statistically significant differences (P < 0.05) in heterophil, lymphocyte, monocyte, eosinophil, and basophil values among treatments. In general, the differential counts of FMG- and MS-infected birds were characterized by heterophilia, lymphopenia, monocytosis, eosinopenia, and basopenia. Histopathologic examination of the spleen, liver, kidney, and bone marrow revealed a high degree of lymphoid foci within the spleen and bone marrow of all infected chickens. In the chronic study (Trial 2), no statistically significant differences (P < 0.05) were observed in differential leukocyte counts, PCV, and plasma protein values among treatments. Histopathologic examination of spleen, liver, kidney, and bone marrow did not reveal any difference among treatments.