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1.
An egg-production function was constructed, using data collected from 366 commercial layer flocks in California, to predict the impact of Mycoplasma gallisepticum (MG) and M. synoviae (MS) on egg production while controlling for confounding factors. In the first and second cycles, respectively, an MG-infected flock produced 12 and 5 fewer eggs per hen than an uninfected flock. Flocks that became infected with MG after F-strain vaccination produced 6 eggs/hen more than unvaccinated infected flocks in the first cycle, but no significant difference was observed between such groups in the second cycle. No association was found between MS-infection and egg production. Commercial layer producers in Southern California lost an estimated 127 million eggs because of MG in 1984. This lost egg production and associated MG-control-program costs amounted to an estimated financial loss of approximately $7 million. This represented a loss of approximately $6 million in consumer surplus.  相似文献   

2.
OBJECTIVE: To assess the effects of electromagnetic (EM) field modification by use of Nufield EM field modification (NEFM) units on egg-laying hens in commercial flocks as indicated by production measures, including hen-day mortality rate (HDMR) and eggs per hen housed (EHH). ANIMALS: 16 commercial flocks of egg-laying hens. PROCEDURE: 5 caged commercial table egg layer flocks (Single Comb White Leghorns) successively housed at the same location during a 6-year period were exposed to NEFM.There were 7 hens/cage (317 cm2 of floor space/bird). At the same site, 11 concurrent non-NEFM-exposed flocks (4 genetically different strains) were sequentially housed. All 16 flocks underwent the same feed and management practices. For each NEFM- and non-NEFM-exposed flock, HDMR and EHH were compared with their respective national breeder goals (BG), defined as the reasonable genetic potential expressed under optimal management and environmental conditions. Furthermore, the HDMRs and EHHs of the NEFM- and non-NEFM-exposed flocks were compared. RESULTS: Mean HDMR and EHH of the NEFM-exposed flocks was 36.9% less and 4.96% greater than the relevant BG, respectively. Mean HDMR and EHH of the non-NEFM-exposed flocks was 12.6% and 0.49% greater than the relevant BG, respectively. Compared with the 11 non-NEFM-exposed flocks, the NEFM-exposed flocks collectively had a 47.6% decrease in HDMR and 1.33% increase in EHH. CONCLUSIONS AND CLINICAL RELEVANCE: Results strongly suggest that application of NEFM in commercial egg-layer flocks improves production measures, which has important welfare implications as well as gross economic advantage.  相似文献   

3.
(1) To evaluate the effect of climate, flock size, age and artificial cover on the use of range area, a study was conducted in 1994 to 1998, involving 5 farms with a total of 37 flocks of layers kept in commercial, free-range, organic systems. Flocks were visited regularly during the production period to record the number and distribution of hens on the range. (2) On average 9% of the flock used the range area, but with large variations both within and between flocks, and this was partly influenced by climatic factors. Range use was affected by temperature, wind, precipitation, season and age, and there was a tendency for reduced numbers of hens on the range with the time of day and increasing flock size. (3) Eight flocks (including houses and range areas) were divided into 8 paired units, and the range area of one unit in each of the flocks was provided with artificial cover. There were more hens on the range when artificial cover was present and the presence of cover attracted more hens away from the area immediately outside the hen house.  相似文献   

4.
An investigation of 52 egg production units showed that in battery units, but not under other systems of husbandry, the proportion of defective eggs produced by birds in their second year was more than twice that of the first year. The proportion of defective eggs was unrelated to the shell thickness (measured by the deformation test on random samples of sound eggs from the same flocks). Damage to eggs during collection and packing was trivial, relative to the proportions of defective eggs found in the nests or cages.  相似文献   

5.
1. Four Japanese quail lines were developed using 13 generations of reciprocal recurrent (lines AA and BB) or within-line selection (lines DD and EE) for high egg number until 98 d of age. In these lines and their reciprocal crosses, egg production, egg weight and mortality were monitored for up to 21 months to evaluate the impact of selection method and line origin on long-term production and heterosis. 2. Both hen-housed total egg number (EN) and hen-day egg laying rate (ELR) were consistently lower in recurrent lines than in lines under within-line selection: after 13 months of test, the difference was -47.1 eggs for EN and -20% for ELR%, whereas mortality was similar at around 20%. 3. Line EE was the best pure line for early egg production (55.2 eggs at 98 d of age) and also gave eggs which were consistently about 2 g larger than those from line DD but it had the highest overall mortality (78.5%) of all lines. On average, line DD laid 399 eggs (EN) over the whole experiment, 84 more than Line EE. 4. Crossbreds from the 2 types of pure lines and line DD had similar patterns and rates of egg production during the whole experiment, as indicated by the similarity of the curves adjusted for those lines by using the monomolecular model for EN and the modified compartmental model for ELR. 5. However, heterosis was higher from recurrent selection lines and it increased more with time than did heterosis from within-line selection lines.  相似文献   

6.
In our laboratory, we have often had difficulty infecting neonatal chickens with invasive salmonellae when ambient temperatures exceed 30 C. We hypothesized that this increased resistance in chicks during warmer months may be associated with heat stress-associated maternal factors. Presently, single-comb white leghorn hens were separated into a non-heat-stressed group, reared under temperatures from approximately 10 to 24 C, and a heat-stressed group, in which environmental temperature was incrementally elevated to near 37 C and maintained for the duration of the 13-wk study. For Expt. 1, eggs from heat-stressed or control hens, collected on days 8-14 of the study, were pooled respective to treatment and incubated. At the time of egg collection, mean hen-day egg production was 51.83% or 65% for heat-stressed or control hens, respectively. On day of hatch, progeny from hens in each group were orally challenged with 0.9 x 10(4) colony-forming units (CFU) Salmonella enteritidis (SE). Rates of SE organ invasion of 97.3% or 94.4% were obtained in progeny from heat-stressed or control hens, respectively. In Expt. 2, eggs from heat-stressed or control hens from days 30-42 of the study were collected and pooled by treatment for incubation. Mean hen-day egg production was 46.5% or 72.85% for heat-stressed or control hens, respectively. On day of hatch, progeny were orally challenged with either 2.2 x 10(3) or 2.2 x 10(4) CFU SE. A 100% incidence in SE organ invasion was observed in all groups. In Expt. 3, eggs were collected from days 43 through 56 of the study. Mean hen-day egg production was 19.8% or 76.8% for heat-stressed or control hens, respectively. On day of hatch, progeny were orally challenged with 2 x 10(3) CFU SE. Rates of SE organ invasion of 95.8% or 95.6% were obtained in progeny from heat-stressed or control hens, respectively. These data suggest that factors other than elevated temperature may be responsible for seasonal resistance to invasive salmonellae infection in neonatal chickens observed in our laboratory during warmer months in Texas.  相似文献   

7.
A survey of anthelmintic resistant nematodes was conducted in sheep and goat flocks in Greece using in vivo and in vitro tests. Faecal egg count reduction tests in Macedonia were all greater than 99% indicating very high sensitivity of the nematodes to anthelmintics. In vitro tests showed benzimidazole resistant Teladorsagia circumcincta in 17 out of 106 flocks on small islands. On the mainland there were only three cases of benzimidazole resistance out of 310 flocks and animals had recently been introduced to the flocks. Flocks on the islands are isolated and there are higher temperatures than on the more mountainous mainland, where flocks tend to intermingle. It is concluded that drought and isolation are likely to be the major factors accounting for the development of anthelmintic resistance in nematodes in the island flocks.  相似文献   

8.
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9.
One hundred twenty-nine multiplier breeder turkey flocks on 45 premises in California were monitored for outbreaks of fowl cholera (FC) (Pasteurella multocida) for 1 year (Aug. 1, 1985, through July 31, 1986). Fourteen (11%) flocks on 10 (22%) premises experienced outbreaks. Nine (64%) outbreaks occurred in the fall or winter. FC-outbreak flocks had significantly shorter lay cycles (24.6 weeks vs. 27.9 weeks) and correspondingly lower total egg production per hen (84 eggs vs. 103 eggs) than non-outbreak flocks. A case-control investigation was performed on 11 FC-outbreak (case) flocks, and nine non-outbreak (control) flocks. Case flocks were located statistically closer to other livestock species than were control flocks (0.28 miles vs. 0.68 miles) and were more likely to utilize on-farm disposal of dead birds.  相似文献   

10.
1. The prevalence and severity of foot pad dermatitis (FPD) was examined in 359 flocks of broiler chickens comprising about 3.93 million birds produced on 91 farms and reared under 5 types of system: standard intensive, free-range, organic, systems complying with the RSPCA Freedom Food scheme, and corn-fed. 2. The mean prevalence of FPD in standard systems was 14.8%. Flocks that had access to the outside (free-range and organic systems) showed higher prevalence of FPD than those kept entirely indoors (standard, corn-fed and Freedom Food systems). The lowest prevalence of FPD (9.6%) and severity of the lesions occurred in Freedom Food systems, and the highest prevalence (98.1%) and severity in organic systems. 3. The implication from the results is that there are large variations in the prevalence and severity of FPD in birds reared under different systems and this needs to be taken into account when assessing the overall welfare associated with each type of system.  相似文献   

11.
1. A study was conducted to evaluate whether feed supplementation with thymol or isoeugenol can alter Japanese quail growth rate and final body weight, the female onset of puberty, hen-day egg production and the physical and chemical characteristics of the egg, as well as its potential to alter hatchability.

2. From 4 to 16 weeks of age, birds from each cage (1 male: 3 females) were assigned to 1 of 3 treatments that differed in the supplement added to the feed: control, thymol or isoeugenol (400?mg/kg). The average ages (d) at first egg lay (FIRST), at 25% egg production (A25% EP), at 50% egg production (A50% EP) and weekly and cumulative hen-day egg production (HDEP) were calculated. In addition, physical and chemical characteristics of the eggs, their fertility and hatchability were also evaluated for each group.

3. Feed supplementation did not significantly affect growth rate, final body weight, egg production parameters, fertility and physical characteristics of egg or most of the fatty acid components of the yolk.

4. The group treated with isoeugenol showed an increase in the percentage of palmitoleic fatty acid compared to the control, with thymol group showing intermediates values.

5. Both thymol and isoeugenol supplemented groups showed increased hatchabilities, by 18·8% and 11·8%, respectively, compared to their control counterparts.

6. The improvement in the hatching success of the eggs from the thymol and isoeugenol supplemented groups without a negative impact on their performance may have important economic implications for future breeding programmes, particularly if these effects generalise from quail to other more commercially important poultry species, such as chickens or turkeys.  相似文献   

12.
1. In the Netherlands aviary systems are in use on 19 commercial farms. In the present study the results of 19 flocks kept in aviaries, with an average flocksize of 16,000 hens, were analysed and compared with 47 flocks kept in battery cages.

2. The aviary flocks had lower egg weights, lower mortality rates and poorer food conversion. The difference in food intake per hen per day was not significant. The average percentage of floor eggs in aviaries was 4.6, ranging from 0.9 to 11.5.

3. Production costs per kg eggs produced in aviaries were 8.2% greater than in cages. This increase was mainly caused by higher costs for pullets, housing and labour.  相似文献   


13.
A study was conducted to evaluate effects of cassava root chips (CRC) andMoringa oleifera leaf meal (MOLM) inclusion in layer rations on egg laying performance, egg quality parameters, fertility, and hatchability. One hundred twenty Dominant CZ layers, 22 wk of age, and 12 cocks were used and equally divided into 4 dietary treatments with 3 replications. Treatment rations contained CRC and MOLM [i.e., T1 (0% CRC and 0% MOLM), T2 (50% CRC and 0% MOLM), T3 (0% CRC and 5% MOLM), and T4 (50% CRC and 5% MOLM)]. The CRC and MOLM were used to substitute for 100% corn grain and 5% soybean meal, respectively. Hens were weighed at the start and end of the experiment and BW change was calculated. Data on DM intake, hen-day egg production, egg weight, and egg mass were recorded daily. Egg quality parameters were determined at an interval of 15 d on 4 eggs per replicate. Fertility and hatchability of eggs, as well as mortality of birds and embryonic mortality of fertile eggs during the incubation period were recorded. From the chemical analysis, the calculated ME content of CRC was 3,852 kcal/kg of DM and the CP content of MOLM was 28%. The DM intake of birds, hen-day egg production, egg mass, FE, and mortality rate were not influenced by treatments. Body weight change and egg weight were higher for T4 as compared with other treatments. Most external and internal egg quality parameters, especially yolk color, were improved when the diet contained MOLM. Fertility showed nonsignificant differences among treatments. However, hatchability percentage for T1 was lower than the other treatments. In conclusion, CRC at 50% of the diet, CRC replacing corn grain 100%, or MOLM at 5% of the diet replacing soybean meal can impart similar or better positive effects on egg production, egg quality parameters, eggs fertility, and hatchability of Dominant CZ layers. Thus, 50% CRC, 5% MOLM, or a combination of both can successfully be used in the diet of layers as energy and protein feed ingredients, respectively.  相似文献   

14.
The present study was conducted to investigate the effect of long-term feeding of conjugated linoleic acid (CLA) and fish oil on egg quality characteristics, production performance, liver pathology, and egg fatty acid content of laying hens. Single Comb White Leghorn laying hens (n = 112), 21 wk old, were placed in cages and randomly assigned to 4 diets (28 hens/diet, 4 replicates of 7 hens) containing 3.0% yellow grease (control), 2.75% yellow grease + 0.25% CLA (YG-CLA), 2.5% yellow grease + 0.25% CLA + 0.25% fish oil (YG-CLA-FO), and 2.75% yellow grease + 0.25% fish oil (YG-FO). The experimental diets were fed for 12 mo. Eggs were collected daily for 12 mo. Feed consumption, hen-day egg production, and feed efficiency were monitored. At the end of the trial, hepatic tissue was collected for histopathology. No effect of diet was found on feed consumption, hen-day egg production, feed efficiency, egg weight, yolk weight, shell weight, or Haugh unit. The YG-CLA and YG-CLA-FO diets produced an increase in CLA and saturated fatty acids in the egg and liver tissue with a concomitant reduction in monounsaturated fatty acids (P < 0.05). Feeding YG-CLA-FO and YG-FO increased the n-3 fatty acids in egg yolk and liver of hens (P < 0.05). No difference was observed in the number of fat vacuoles in the liver tissue. The total fat content of hepatic and abdominal fat pads did not differ among treatments (P > 0.05). Regardless of the diet, as the hens aged, egg weight, yolk weight, and egg total fat increased, and shell weight decreased (P < 0.05). These data demonstrate that eggs with increased n-3 fatty acids and CLA can be generated by minor diet modifications without affecting the production performance or health of birds.  相似文献   

15.
1. Sample fertility and the median number of points of hydrolysis produced by spermatozoa in the perivitelline layer from the germinal disc area were determined in samples of 60 eggs taken weekly from each of two commercial broiler breeder flocks. 2. Flock fertility remained above 90% from weeks 30 to 45, after which it fell in both flocks, reaching 85% in Flock A by week 51 and 76% in Flock B by week 55. 3. Sample fertility, as assessed by the Kosin test, followed a similar trend, but showed more variation; the same was true for the proportion of eggs with at least one perivitelline hole. 4. In Flock A, the median number of perivitelline holes in samples increased from 145 in week 30 to reach a maximum of 323 on week 39, thereafter falling to 109 in week 51; for Flock B, the equivalent figures for weeks 30, 36 and 55 were 160, 266 and 29, respectively. A quadratic model confirmed that the weekly sample median perivitelline holes peaked at weeks 40 and 37 in Flocks A and B, respectively. 5. The results show that transfer of spermatozoa by males into females and subsequently into eggs begins to decline 8 (Flock A) to 9 (Flock B) weeks before it is noticeable as a significant reduction in flock fertility and that mating efficiency, unlike fertility, is never in apparent equilibrium, but rises to a peak before 40 weeks and then falls. 6. The pattern of sperm transfer suggests that the reduction in fertility of broiler flocks could well be for social or for physiological reasons other than those associated with 'ageing'.  相似文献   

16.
Rearing conditions and foot-pad dermatitis in Swedish broiler chickens   总被引：1，自引：0，他引：1  
A method of classification of broiler foot-health status was developed to estimate the prevalence of foot-pad dermatitis in Swedish broilers. Data on foot health were collected from 101 commercial broiler flocks at slaughter. The producers were asked to fill in a questionnaire on rearing conditions and equipment for every flock.

Lesions were commonly observed; only 62% of the birds were classified as being without lesions, 32% had mild lesions only (discoloration, erosions) and 6% had severe lesions (ulcers). Flocks reared in houses equipped with small water cups had significantly (P < 0.05) higher prevalences of foot-pad dermatitis than flocks reared with water nipples. Thick layers of litter, regardless of litter material, also resulted in significantly (P < 0.05) higher prevalences of foot-pad dermatitis than litter layers thinner than 5 cm.  相似文献   


17.
Behaviour of laying hens in a deep litter house   总被引：4，自引：0，他引：4  
1. Flocks of medium hybrid laying hens were housed in a modified deep litter system; the house was divided into 2, 3 and 4 pens in three successive years. Flock size was 300 or 370 and stocking density varied from 3.4 to 10.7 birds/m2. Higher densities used were above those recommended by the Ministry of Agriculture, Fisheries and Food (MAFF). 2. A random sample of 100 birds was identified with individual tags in each of the 9 flocks; regular observations using a scanning technique were made in each laying cycle to determine bird location and behaviour. 3. In all flocks the use of area by some individuals was uneven, that is, they were sighted in certain areas significantly more often than would have been expected by chance. The proportion of such individuals varied between flocks from 35 to 65%. Overall, birds spent more time on the slatted area than would have been expected from the area that it occupied. 4. A wide variety of different behaviour patterns was observed both on litter and on slats, but with foraging occurring more on litter and feeding more on slats. 5. Movement appeared to be constrained by crowding, because time spent in locomotion decreased in approximately linear fashion with increased stocking density. This provides support for MAFF recommendations of limits on stocking density in deep litter houses.  相似文献   

18.
Prevalence was estimated for Salmonella enterica serotype eneritidis (SE) in layer house environments (n = 200 layer houses) and house mice (n = 129 layer houses) in 15 states throughout the United States. Environmental swabs were collected from manure, egg belts, elevators, and walkways. Live-catch rodent traps were placed for 4-7 days. Swabs and house mice were submitted to the laboratory for bacterial culture. Overall, 7.1% of layer houses and 3.7% of mice were culture positive for SE. The highest prevalence was in the Great Lakes region of the United States, and no SE was recovered from houses or mice in the southeast region. Presence of SE in layer houses was associated with age/molting, floor reared pullets, and number of rodents trapped. Cleaning and disinfecting houses between flocks was associated with a reduced risk. The prevalence of SE in mice from environmentally positive houses was nearly four times that of mice from environmentally negative houses.  相似文献   

19.
Seven Canadian layer flocks with Salmonella enteritidis in their environment were investigated to determine the numbers of hens infected with S. enteritidis, the localization of S. enteritidis in organs of infected hens and the numbers of S. enteritidis-infected eggs produced by two affected flocks. By a microagglutination test (MAT) using S. pullorum antigens, these flocks had more seropositive hens (mean 51.9 +/- 16.9%) than two Salmonella-free flocks (mean 13.0 +/- 4.2%). Culture of tissues of 580 hens (433 seropositive) from the seven flocks detected 26 (4.5%) S. enteritidis-infected hens from two flocks. In one flock, 2/150 hens were infected with S. enteritidis phage type (PT) 8, which was confined to the ceca, and no Salmonella spp. were isolated from 2520 eggs (one day's lay). In the second flock, where 24/150 hens were infected with S. enteritidis PT13, extraintestinal infection was found in nine hens and involved the ovaries and/or oviduct in two hens. Salmonella enteritidis PT13 was isolated from one sample of egg contents and from one sample of cracked shells from among 14,040 eggs (one day's lay) from this flock. The overall prevalence of S. enteritidis-contaminated eggs from the two flocks with infected hens was less than 0.06%. Other Salmonella spp. isolated were S. heidelberg from 58 hens (10%), and S. hadar, S. mbandaka and S. typhimurium from one hen (0.2%) each. The MAT with antigens of S. pullorum had a sensitivity of 81% and a specificity of 24% for detecting S. enteritidis-infected hens.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   

20.
Mycoplasma synoviae (M. synoviae) can cause respiratory disease, synovitis, or result in a silent infection in chickens and turkeys. The importance of M. synoviae is well established in broilers but only a few studies have been conducted in layers. In the present study, the prevalence of M. synoviae in commercial layer flocks was estimated using ELISA. For this study, 19 commercial layer flocks were selected randomly from New South Wales and Queensland region of Australia from producers who were willing to participate in the survey. Sixty eggs per flocks were randomly collected, out of these 30 eggs were used for ELISA and remaining 30 eggs were used to estimate various egg shell quality parameters. Subsequently, association between the serological status of eggs for M. synoviae and egg shell quality was studied. In the flocks under study, seroprevalence of M. synoviae was found to be high at 69% (95% confidence interval (CI)=41.3-89.0). Statistical analysis showed an association between serological status for M. synoviae and egg quality parameters such as translucency, shell breaking strength, % shell reflectivity and shell deformation. On the other hand, there was no significant association between serological status for M. synoviae and other egg quality parameters such egg weight, egg shell weight, % egg shell or shell thickness.  相似文献   

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