College of Animal Science and Technology, Anhui Agricultural University, Hefei , P. R. China

Transcription

1 Influences of F-strain Mycoplasma gallisepticum vaccine on productive and reproductive performance of commercial parent broiler chicken breeders on a multi-age farm J. J. Liu, L. Ding, J. Z. Wei, and Y. Li 1 College of Animal Science and Technology, Anhui Agricultural University, Hefei , P. R. China ABSTRACT The influences of F-strain Mycoplasma gallisepticum (FMG) vaccine inoculation during the pullet period on the subsequent productive and reproductive performance of parent broiler chicken breeders on a multi-age farm were evaluated. Three thousand breeders were randomly divided into 2 treatment s that were either vaccinated with FMG ( ) or not vaccinated with FMG ( ). Body weight and egg production were determined through approximately 50 wk of age. Egg weight and feed conversion was determined at 26, 32, 35, 38, and 43 wk of age. Egg quality parameters, including eggshell strength, egg-specific gravity, egg shape index, blood-meat spots, Haugh unit score, eggshell thickness, yolk:albumen ratio, percentage yolk, albumen and eggshell weights, and percentage fertility, hatchability, and second-quality chicks were determined at 26, 32, and 43 wk of age. Air sacs were examined and lesions were scored at 20, 32, and 50 wk of age. The number of mature ovarian follicles, histologies of ovary, and lengths, and histologies of the infundibulum, magnum, isthmus, INTRODUCTION Mycoplasma gallisepticum is a pathogenic organism that can infect chickens and cause chronic respiratory disease (Burnham et al., 2002a). In poultry, M. gallisepticum infection is spread vertically through infected eggs and horizontally by close contact (Austic and Nesheim, 1990; OIE, 2008). It has been speculated that M. gallisepticum infection can also spread through the blood from the hen s respiratory tract to the oviduct, causing reduced egg production (EP) and hatchability and poor egg quality (Domermuth et al., 1967; Kempf and Gesbert, 1998; Burnham et al., 2002b). Chronic uterus, and vagina were determined. In the present study, an increase in egg production of broiler breeder hens in the during peak of lay was compared with the. Feed conversion of hens in the was significantly less at 32, 35, 38, and 43 wk of age. Eggs from hens in the had a significantly higher Haugh units score at 26 wk of age and had a significantly higher eggshell thickness and lower incidence of blood-meat spots at 32 wk. Hatching eggs from hens in the had a significantly higher hatchability. The mean lesion score of air-sac lesion of birds in the was significantly less than. Uteruses of hens in the had a significantly longer length compared with the at 32 wk of age. The results indicate that inoculation of commercial parent broiler chicken breeders with the FMG vaccine before laying may prevent infection by field M. gallisepticum, and facilitate productive and reproductive performance. Key words: productive performance, reproductive performance, F-strain Mycoplasma gallisepticum vaccine, parent broiler chicken breeder, multi-age farm 2013 Poultry Science 92 : /ps Poultry Science Association Inc. Received December 26, Accepted February 17, Corresponding author: liyu@ahau.edu.cn respiratory infections associated with M. gallisepticum have a high prevalence throughout the world with significant economic impacts on the poultry industry (Mudahi-Orenstein et al., 2003), and are often associated with a concurrent virus or bacterial infection, such as Newcastle s disease, infectious bronchitis, infectious bursal disease, Escherichia coli, Pasteurella, and Hemophilus species (Kleven, 1998). Three different tools can be used to control M. gallisepticum: eradication-maintained M. gallisepticumfree flocks, medication with various antibiotics, and vaccination. In the United States, all major breeder flocks generally remain free of M. gallisepticum through monitoring and eradication programs (Barbour et al., 2000; Hein, 2004). However, eradication is impractical in multi-age poultry production farms once field M. gallisepticum organisms are introduced (Kleven et al., 1984). Peculiarly, in developing economies such as 1535

2 1536 Liu et al. China, eradication is proving hard to enforce, and it is even difficult to sustain the gains achieved in practical work limited by their scales of breeding, the level of management, environmental control, and so on. It is inefficient to prevent and control M. gallisepticum by medication because a medication may not eliminate M. gallisepticum from a flock and the birds are capable of transmitting the M. gallisepticum horizontally as well as vertically (Hein, 2004). There are also other problems such as high cost and drug residues. Therefore, vaccination has become the main approach in controlling M. gallisepticum. Currently, 2 types of vaccines, live and inactivated vaccines, are available for the control of M. gallisepticum. Inactivated vaccines could play a certain role in the control, but there are disadvantages such as high labor cost, local reactions at the injection site, lack of effectiveness in eliminating M. gallisepticum, and other disadvantages. Kleven (1997) indicated that live M. gallisepticum vaccines could be effective in controlling economic losses and may be used as tools in eradication programs. Cell-mediated immunity is thought to play a role in the systemic and local antibody responses to M. gallisepticum (Gaunson et al., 2000; Noormohammadi et al., 2002). Live M. gallisepticum vaccine is a better option to protect against M. gallisepticum infection than inactivated vaccines (Hein, 2004). Available live M. gallisepticum vaccines applied widely are produced from the F strain M. gallisepticum (FMG), and more recently, ts-11 strain M. gallisepticum (ts-11) and 6/85 strain M. gallisepticum (6/85; OIE, 2008). Producers in the United States experienced a re-emergence of more pathogenic strains of M. gallisepticum in flocks vaccinated with either the ts-11 or 6/85 vaccine that resulted in unnecessary economic loss (Poultry Technical Services Team, 2005). Compared with either ts- 11 or 6/85 vaccine, chickens vaccinated with the FMG vaccine in the field show significant protection against virulent M. gallisepticum. Early inoculation or vaccination with FMG may help reduce losses in the performance of birds as a result of infection by field strains of M. gallisepticum (Luginbuhl et al., 1976; Yoder et al., 1984). Furthermore, consistent use of FMG vaccine could displace more virulent endemic M. gallisepticum populations (Kleven et al., 1990; Brown et al., 1995; Peebles and Branton, 2012), so as to achieve the purpose of eliminating M. gallisepticum in the future. The objective of the present study was to understand and explore influences of FMG vaccination before laying on productive and reproductive performance of commercial parent broiler chicken breeders on a multiage farm, through evaluating BW, laying performance, egg quality parameters, fertility and hatchability of hatching eggs, and so on, throughout a complete egg laying cycle in Lingnan Yellow broiler chicken breeders inoculated with the FMG vaccine at 1 d and again at 12 wk of age, and characterizing possible physiological changes, including air-sac lesions and reproductive organ characteristics. MATERIALS AND METHODS Pullet Housing and Management Three thousand 1-d-old pullets of a single genetic strain, Lingnan Yellow Chicken, were obtained from a commercial source that was randomly divided into 2 treatment s that were either vaccinated with FMG ( ) or not vaccinated with FMG ( ). The breeder flocks, which were certified as free of M. gallisepticum, were reared on the same multi-age farm with a long history of mycoplasmosis. Pullets in the brooding period, up until the time that they were 7 wk of age, were maintained on clean dry litter in a conventional house. Flock density at placement was 30 birds/m 2. At 8 d and again at 4 wk of age, chickens were also vaccinated for Newcastle disease and infectious bronchitis via drinking water. Pullets were vaccinated at 2 wk and again at 5 wk of age for infectious bursal disease by the same route. At 7 wk of age, hens that had a sex identification problem or did not meet the criteria for color pattern, size, and appearance were eliminated. Subsequently, all the remaining pullets were transferred to the cage facilities that had been thoroughly disinfected. Flock density at placement was 20 birds/m 2. The hens from the and were reared in 2 different henhouses. A certain proportion of breeder cocks were reared in each henhouse, and the cocks of the were treated as hens. At 12 wk of age, each treatment was randomly divided into 4 replicate units. Lighting was maintained at 13 h per day before laying. Beginning at the onset of lay, the artificial lighting schedule was increased 0.5 h/wk until a 16L:8D cycle was achieved. Broiler breeders were maintained on that schedule through the remainder of the experiments. For the entirety of the trial, broiler breeders had ad libitum access to water. Their diets were provided over the course of the trial as follows: 0 to 7 wk, starter; 7 wk to onset of lay, grower; and onset of lay to conclusion of experiment, layer. These diets were formulated with the appropriate ingredients. Commercial animal feeding operations were maintained as much as possible. FMG Inoculation Pullets in the vaccinated treated with FMG were inoculated via eye drop in the right eye at 1 d and 12 wk of age with 0.03 ml of FMG vaccine marketed by Nanjing Tianbang Bio-Industry Co. Ltd., Nanjing, China. Similarly, pullets designated as controls were sham-inoculated via eye drop in the right eye with 0.03 ml of PBS. Pullets in which antibiotics are being used (especially those with anti-mycoplasma activity) must be avoided within 2 to 4 d after vaccination and at least 20 d after vaccination.

3 Mycoplasma Detection Cotton swab samples were collected from tracheas of 20 randomly selected broiler breeder hens of each treatment at each of 7 ages (5 d, and 12, 20, 26, 32, 43, and 50 wk). Each of these samples was tested for the presence of FMG and virulent strain of M. gallisepticum (VMG) by the duplex PCR method described by Ding et al. (2011). The virulent strain R of M. gallisepticum as a positive control for PCR test for detection of VMG was provided by Nanjing Tianbang Bio- Industry Co. Ltd. Productive Performance Individual BW of 20 randomly selected broiler breeder hens in each were recorded at 12, 16, 20, 23, 26, 29, 32, 35, 38, 41, 43, 47, and 50 wk of age. Commensurate with the production of the first egg (22 wk of age), eggs from both s were collected daily until trial termination at 50 wk. Egg production data for FMGvaccinated and broiler breeder hens were expressed as percentage hen-day production. Eight eggs per unit were collected to determine egg weight (EW) at 26, 32, 35, 38, and 43 wk of age. During those same weeks listed above for EW, 4 units in each were used in a study for the determination of feed conversion (g of feed intake/g of eggs produced). Total feed consumed and numbers of eggs produced per unit were recorded each week to derive feed conversion. After eggs were weighed, eggs were collected at 26 (prepeak), 32 (peak), 43 wk of age (postpeak) to determine egg quality parameters. Eggshell strength (ESS) was measured using an eggshell strength meter (FHK NFN388, Fujihira Industry Co. Ltd., Tokyo, Japan), egg-specific gravity (ESG) was measured by the method described by Kermanshahi and Classen (2001), egg shape index (ESI) was measured by a egg form coefficient measuring instrument (FHK NFN385, Fujihira Industry Co. Ltd.). Then, blood-meat (B-M) spots and Haugh unit (HU) score were determined by breaking each egg. The B-M spots were determined by using the methods described by Branton et al. (2000). The HU were scored using an egg quality gauge (FHK NFN381, Fujihira Industry Co. Ltd.) and by a technique described by Austic and Nesheim (1990). After the measurement of B-M spots and HU score, eggs were separated, and the yolk, albumen, and eggshell weights were determined and expressed as percentages of EW. Yolk:albumen ratio was expressed as a fraction of the percentages of yolk weight (numerator) and albumen weight (denominator). Eggshell thickness was determined using the same shells used to determine eggshell percentage. Eggshell thickness was measured in 3 points at the egg equator using an eggshell thickness gauge (FHK NFN380, Fujihira Industry Co. Ltd.), and calculating the average among the 3 points (De Reu et al., 2006). F-STRAIN MYCOPLASMA GALLISEPTICUM VACCINE Reproductive Performance Six hundred hatching eggs of each treatment were randomly selected at each of 3 ages (26, 32, and 43 wk). Experimental eggs were collected 2 times daily and stored for 2 d at 14 to 16 C and 65% RH before setting. A total of 1,200 eggs collected at 1 of 3 ages were distributed randomly among 8 incubator trays (150 eggs per tray), with treatment s uniformly represented in each 3 trays. The 8 trays were randomly placed into a single EI incubator (EIF/CXDZ15120, Qingdao Xingyi Electronic Equipment Co. Ltd., Qingdao, China) to 18 d of incubation. The incubator air temperature set point was 37.6 C. Relative humidity was automatically controlled at 55%, and eggs were turned through a 90 angle 12 times daily through 18 d of incubation. Both experimental s were placed in a single hatcher (EICDXDZ15120, Qingdao Xingyi Electronic Equipment Co. Ltd.) at the time of transfer (18 d of incubation) in all experiments. The hatcher air temperature set point was 37.3 C, and RH was automatically controlled at 60%. At the time of removing the chicks from the hatchers (21.5 d of incubation), the number of chicks hatched from each was counted and all unhatched eggs were opened and examined macroscopically by an experienced individual to determine percentage fertility. Percentage fertility was calculated as the number of fertile eggs per 100 hatching eggs set. Percentage hatchability was calculated as the number of chicks hatched per 100 hatching eggs set. Percentage second-quality chicks was calculated as the number that were not able to stand properly or chicks that showed visible signs of poor incubation conditions, such as improperly healed navels, per 100 chicks hatched. Pathologic Examination 1537 At 20, 32, and 50 wk of age, air sacs from 1 randomly selected hen in each of 4 units in both and FMG-clean s were examined and lesions were scored by the method described by Rodriguez and Kleven (1980). At 32 and 50 wk of age, the entire ovary was removed from 1 randomly selected hen in each of 4 units in both s, and the number of mature (diameter 12 mm) yellow ovarian follicles was recorded for each hen as described by Burnham et al. (2002a). Then their oviducts were removed and the lengths of the oviduct, infundibulum, magnum, isthmus, uterus, and vagina were also examined. At 32 and 50 wk of age, one tissue sample from the ovary, infundibulum, magnum, isthmus, uterus, and vagina was harvested from 1 hen in each of 4 units in both s. Tissue samples were prepared into paraffin section as described by Peebles et al. (2006). Each tissue sample was observed and scored for the presence or absence of lymphoid and heterophil infiltrates

4 1538 Liu et al. Table 1. Percentage of F-strain of Mycoplasma gallisepticum (FMG)-positive or virulent strain of M. gallisepticum (VMG)-positive hens at different time intervals in and unvaccinated parent broiler chicken breeder flocks by duplex PCR assay 1 FMG positive VMG positive FMG positive VMG positive 5 d 0 90 (18/20) 0 90 (18/20) 12 wk 65 (13/20) 90 (18/20) 0 95 (19/20) 20 wk 95 (19/20) 75 (15/20) 0 90 (18/20) 26 wk 90 (18/20) 80 (16/20) (20/20) 32 wk 95 (19/20) 75 (15/20) 0 90 (18/20) 43 wk 90 (18/20) 70 (14/20) 0 95 (19/20) 50 wk 85 (17/20) 60 (12/20) 0 90 (18/20) 1 Data are percentages with number positive/number tested in parentheses. as described by Branton et al. (2000). Treatment assignments were unknown to the evaluator during the scoring procedure. Statistical Analyses A completely randomized experimental design was used. All data were analyzed using the MIXED procedure of SAS software (SAS Institute, 2003), except percentages were compared between treatments using t- test. Global effects and differences among least squares means were considered significant at P < RESULTS Survival of FMG and Field M. gallisepticum In parent broiler chicken breeder flocks, all initial PCR test results obtained from 5-dold pullets were negative for FMG (Table 1). Then, at ages 12, 20, 26, 32, 43, 50 wk, percentages of FMGpositive birds were 65 to 95%, and maintained an especially high level ( 85%) after 20 wk of age. In the, however, all PCR test results were negative for FMG during the same period. Percentages Table 2. Body weight (g) of parent broiler chicken breeders at 12, 16, 18, 23, 26, 29, 32, 35, 38, 41, 43, 47, and 50 wk of age in F-strain of Mycoplasma gallisepticum (FMG)-vaccinated and s ,563 1, ,725 1, ,833 1, ,035 1, ,325 2, ,551 2, ,698 2, ,809 2, ,853 2, ,917 2, ,959 2, ,982 2, ,029 3, ,057 3,032 1 n = 20. of VMG-positive hens in were from 60 to 90%. Interestingly, a decreasing tendency was shown, gradually starting from 12 wk of age. However, percentages of VMG-positive birds in maintained a high level ( 90%) over the experimental period. Productive Performance The FMG vaccine main effects were not significant for BW (Table 2). Weekly EP for both s are provided in Figure 1. Initiation of lay was delayed 3 d for broiler breeder hens from the in comparison with those from the. An increase in EP of hens in the began at wk 32 so that EP became significantly more than that of breeding hens in the. This same comparative pattern of EP continued each week from 34 to 41 wk of age. The FMG vaccine main effect (P < 0.05) was observed for feed conversion. Feed conversion of hens in the was significantly less at 32, 35, 38, and 43 wk compared with those in the (Table 3). Instead, there were no significant differences between the different treatment s for EW at 26, 32, 35, 38, and 43 wk of age. Egg quality parameters for both s at 26, 32, and 43 wk of age are provided in Table 4. Eggs from hens in at 26 wk of age had a significantly higher HU score and at 32 wk of age had a significantly higher eggshell thickness and lower incidence of B-M spots compared with the other treatment. There were no significant differences between the different treatment s for other egg quality parameters at 26, 32, or 43 wk of age. Reproductive Performance Fertility, hatchability, and second-quality chicks for both s at 26, 32, and 43 wk of age are provided in Table 5. There were no significant differences between the different treatment s for fertility and secondquality chicks at 26 and 32 wk of age, but eggs from hens in the had significantly higher hatchability compared with the other treatment

5 F-STRAIN MYCOPLASMA GALLISEPTICUM VACCINE 1539 Table 3. Egg weight (g) and feed conversion of parent broiler chicken breeders at 26, 32, 35, 38, and 43 wk of age in F-strain of Mycoplasma gallisepticum (FMG)-vaccinated and s 1 EW (g) Feed conversion (g of feed intake/g of eggs produced) s s ± ± ± ± ± ± ± 0.02 b 3.30 ± 0.05 a ± ± ± 0.02 b 3.76 ± 0.03 a ± ± ± 0.03 b 3.87 ± 0.07 a ± ± ± 0.12 b 3.80 ± 0.08 a a,b Within week of age, means among treatment s with no common superscript differ significantly (P < 0.05). 1 n = 32.. At 43 wk of age, however, there were no significant differences between the different treatment s for fertility, hatchability, and second-quality chicks. Pathologic Examination Air-sac lesions for and s at 20, 32, and 50 wk of age are provided in Table 6. The air-sac lesions observed in was less than that observed in the FMGfree. The number of maximum follicles for both s at 32 and 50 wk of age is provided in Table 7. There were no significant differences between the different treatment s for the number of maximum follicles. Infundibulum, magnum, isthmus, uterus, vagina, and oviduct lengths for both s at 32 and 50 wk of age are provided in Table 8. At 32 wk of age, uteruses of hens in the were significantly longer compared with the other treatment. No significant differences (P < 0.05) were demonstrated between the treatment s for histopathologic lesion scores within any of the tissues sampled (data not shown). DISCUSSION The economic impact of chronic respiratory infections associated with M. gallisepticum on a multi-age farm is enormous. Mycoplasma gallisepticum can cause respiratory tract infection and airsacculitis, and once a bird is infected with M. gallisepticum it is generally considered chronically infected for life (Austic and Nesheim, 1990; Burnham et al., 2002b). Mycoplasma gallisepticum transmission from mature hens to replacement pullets has led to great difficulties in controlling M. gallisepticum. Unfortunately, the implementation of strict biosecurity measures is difficult on multi-age farms, and the most efficient solution may be to establish an M. gallisepticum vaccination program (Bermudez and Kalbac, 1988). The FMG is known to be relatively low in virulence, poorly transmissible, and able to displace the original field strain (Kleven et al., 1990). In the present study, it was found that percentages of VMG-positive birds remained stable, but percentages of VMG-positive birds showed a decreasing tendency gradually over time after FMG vaccine inoculation through detecting the presence of M. gallisepticum. The results show that the FMG vaccine maybe have the ability to displace the virulent field strains of M. gallisepticum. The mean lesion score of air-sac lesion of birds in was 0.75 at 26, 32, and 50 wk of age, significantly less than the. This indicates that FMG vaccine may be capable of offering effective protection for air-sacs of parent broiler chicken breeders. Abd-el- Motelib and Kleven (1993) compared the immune efficacy of 3 live M. gallisepticum vaccine strains (ts-11, 6/85, and FMG) and one of bacterins and observed airsac lesions of vaccinated chickens 10 d postchallenge. The hens had a mean lesion score of air-sac lesions of 0.18, had the best protection against airsacculitis, less protection was observed in the ts-11 and 6/85 s, and mean lesion scores were 1.25 and 1.32, respectively; no protection against airsacculitis was observed in bacterin-vaccinated hens. The FMG vaccine may offer protection for the health of parent broiler chicken breeders against colonization by field strains of M. gallisepticum. Figure 1. Weekly percentage hen day egg production at 22 to 50 wk of age for F-strain of Mycoplasma gallisepticum (FMG)-free ( ) vs. FMG-inoculated ( ) layer hens. Symbols within a week with different letters (a,b) are significantly different (P < 0.05).

6 1540 Liu et al. Table 4. Egg quality parameters of parent broiler chicken breeders at 26, 32, and 43 wk of age in F-strain of Mycoplasma gallisepticum (FMG)-vaccinated and s 1 26 wk 32 wk 43 wk Item Vaccinated 2 Free 3 Vaccinated Free Vaccinated Free ESI 1.29 ± ± ± ± ± ± 0.04 ESG ± ± ± ± ± ± ESS (kg) 4.10 ± ± ± ± ± ± 0.84 PYW (%) ± ± ± ± ± ± 4.95 PAW (%) ± ± ± ± ± ± 4.98 YAR 0.50 ± ± ± ± ± ± 0.16 PSW (%) ± ± ± ± ± ± 0.90 EST (mm) ± ± ± a ± b ± ± HU ± 5.19 a ± 6.40 b ± ± ± ± 7.07 B-M spots (%) b 56 a a,b Within week of age, means among treatment s with no common superscript differ significantly (P < 0.05). 1 n = 25. ESI = egg shape index; ESG = egg-specific gravity; ESS = eggshell strength; PYW = percentage yolk weight; PAW = percentage albumen weight; YAR = yolk:albumen ratio; PSW = percentage shell weight; EST = eggshell thickness; HU = Haugh units; B-M = blood-meat. 2 Means. 3 Means. Along with affecting the respiratory apparatus, M. gallisepticum infection in hens also causes reduced EP and financial losses (Mohammed et al., 1987; Hein, 2004; OIE, 2008). Truscott et al. (1974) and Glisson and Kleven (1984) reported that they were protected against decreases in EP of hens vaccinated with lowvirulence live M. gallisepticum. Carpenter et al. (1981) reported that flocks will produce 7.0 more eggs per hen per year, when the performance of and M. gallisepticum-infected flocks is compared. In the present study, an increase in EP of broiler breeder hens in the during peak of lay was compared with the, and especially EP became significantly more than that of hens in the at 32, 34, 35, 36, 37, 38, 39, 40, and 41 wk of age. The results demonstrate that FMG vaccine inoculation improves EP of hens in during peak of lay and effectively restrain adverse impacts of M. gallisepticum infection. Burnham et al. (2002b) found that all birds inoculated with FMG laid their first egg approximately 1 wk after controls. In this study, however, it was found that initiation of lay of hens in FMGvaccinated was delayed 3 d compared with the. This may be because not all hens in the were infected by M. gallisepticum before laying. Each reproductive tract segment plays a corresponding and important role within a certain time frame on the formation of an egg (Austic and Nesheim, 1990; Johnson, 2000). Mycoplasma gallisepticum may colonize various regions of the female reproductive tract and disrupt egg formation, and consequently result in reduced rates in EP (Burnham et al., 2002a). Mohammed et al. (1987) and Yoder (1991) reported that feed efficiency was reduced in flocks naturally infected with M. gallisepticum. In this study, feed conversion of hens inoculated FMG vaccine on multi-age farms was improved; however, EW was not significantly improved. Mycoplasma gallisepticum may have a unique ability to colonize and impair certain reproductive processes in commercial birds and lead to a delay in the development of the ovary and oviduct during prepeak EP (Carlson and Howell, 1967; Domermuth et al., 1967; Burnham et al., 2002a). In the study, the result that uteruses of hens in were significantly longer compared with the other treatment at 32 wk of age indicates that the FMG vaccine inoculation has a protective function against the effect of M. gallisepticum infection on development of oviduct. The uterus is the location of formation of eggshells, and eggshell formation may be influenced by shortening of the uterus in the. At peak EP Table 5. Fertility, hatchability, and second-quality chicks of hatching eggs from parent broiler chicken breeders at 26, 32, and 43 wk of age in F-strain of Mycoplasma gallisepticum (FMG)-vaccinated and s 1 Fertility (%) Hatchability (%) Second-quality chicks (%) FMG vaccinated 2 FMG free 3 FMG vaccinated FMG free FMG vaccinated FMG free a b a b a,b Within week of age, means among treatment s with no common superscript differ significantly (P < 0.05). 1 n = Means. 3 Means.

7 Table 6. Air-sac lesions in F-strain of Mycoplasma gallisepticum (FMG)-vaccinated and s at 20, 32, and 50 wk of age 1 F-STRAIN MYCOPLASMA GALLISEPTICUM VACCINE 1541 Table 7. Number of maximum follicles in F-strain of Mycoplasma gallisepticum (FMG)-vaccinated and s at 32 and 50 wk of age 1 Mean score air-sac lesions ± 0.47 b 2.50 ± 0.29 a ± 0.25 b 2.00 ± 0.41 a ± 0.25 b 2.50 ± 0.29 a a,b Within week of age, means among treatment s with no common superscript differ significantly (P < 0.05). 1 Within each column, 1 hen was sampled from each of 4 replicate units for the calculation of treatment means. (32 wk of age), eggs from hens in the had a significantly higher eggshell thickness compared with the. The characteristics of eggshell are thinness and porousness, and it has been proposed that the mechanical properties of the shell that ensure the integrity of the diffusion pathways throughout incubation are of equal importance to those that protect the embryo from mechanical damage (Tullett, 1984; Paganelli et al., 1987). The pore rate of eggshell increased and the water vapor conductance improved when shell thickness increased in the FMGvaccinated, and consequently the hatchability of hatching egg was affected. Besides, hatchability of the hatching egg was affected by HU or incidence of B-M spots. The results for determination of egg quality show that eggs from hens in the at 26 wk of age had a significantly higher HU score and at 32 wk of age had lower incidence of B-M spots compared with the. Interestingly, eggs from hens in the had a significantly higher hatchability compared with the at 26 and 32 wk of age. Quality of the egg may affect hatchability (Heier and Jarp, 2001; Wolc et al., 2010). Previous work also has shown that M. gallisepticum is transmitted to chicks through the egg in hens infected by M. gallisepticum (Glisson et al., 1984; Glisson and Kleven, 1984; Barbour et al., 2000). The FMG vaccine produces persistent protection for reproductive systems of Mean number of maximum follicles hens and dramatically reduces the vertical transmission of M. gallisepticum (Poultry Technical Services Team, 2005; Olanrewaju et al., 2009), consequently hatchability of hatching egg is increased significantly. The maintenance of M. gallisepticum-free breeder flocks through eradication remains the best method of M. gallisepticum control; however, even though most commercial poultry flocks in developed countries such as the United States are raised free of M. gallisepticum via strategic biosecurity and monitoring programs, they are still at risk of infection (Burnham et al., 2002b; Hein, 2004). Consequently, M. gallisepticum vaccines could still play an important role in controlling M. gallisepticum currently. The results in the study show improved and enhanced EP, feed conversion, egg quality, and hatchability of hatching eggs from broiler breeder hens inoculated with the FMG vaccine, and indicate that it may effectively reduce the risk associated with field M. gallisepticum and facilitate the productive and reproductive performance of commercial parent broiler chicken breeders by FMG vaccine inoculation before laying on a multi-age farm. ACKNOWLEDGMENTS ± ± ± ± Within each column, 1 hen was sampled from each of 4 replicate units for the calculation of treatment means. This work was funded by the International Science & Technology Cooperation Plan of Anhui Province ( ) and the Poultry Industrial System of Anhui Province. Table 8. Infundibulum, magnum, isthmus, uterus, vagina, and oviduct lengths (cm) in F-strain of Mycoplasma gallisepticum (FMG)-vaccinated and s at 32 and 50 wk of age 1 32 wk 50 wk Item Infundibulum 9.1 ± ± ± ± 1.0 Magnum 30.4 ± ± ± ± 1.3 Isthmus 8.1 ± ± ± ± 1.0 Uterus 8.1 ± 0.5 a 7.3 ± 0.5 b 8.5 ± ± 1.0 Vagina 7.8 ± ± ± ± 1.3 Oviduct a,b Within week of age, means among treatment s with no common superscript differ significantly (P < 0.05). 1 Within each week, 1 hen was sampled from each of 4 replicate units for the calculation of treatment means.

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