Received May 21, 2014; accepted August 10, 2014 相似文献
Received February 24, 2015; accepted September 7, 2015 相似文献
This is the first study to reveal gill lesions typical for columnaris disease at macroscopic, light microscopic, and ultrastructural levels in both Common Carp and Rainbow Trout following a challenge with F. columnare. The results provide a basis for research opportunities to examine pathogen–gill interactions.
Received January 10, 2014; accepted July 27, 2014 相似文献
2. Body weight at 169 d of age varied from, on average, 1409 g (15 °C, ad libitum) to 943 g (30 °C, 70% schedule) for the white strain and 1947 to 1250 g for the same treatments respectively for the brown strain. Sexual maturity was considerably delayed by the 70% feeding schedule, only slightly by rearing at 30 °C.
3. Rearing at 30 °C tended to depress subsequent egg output. The 70% feeding schedule at least maintained egg output compared with birds fed ad libitum in rearing.
4. There was a highly significant effect of temperature treatment during lay on food intake. The reduction in food intake due to the 21–28 °C cycle, however, appeared small. 相似文献
Received October 27, 2015; accepted April 13, 2016 Published online August 2, 2016 相似文献
Received April 6, 2015; accepted August 25, 2015 相似文献
Received May 1, 2014; accepted July 10, 2014 相似文献
2. The following semen processing conditions were studied: spermatozoa working concentration (SWC), 1.5 vs 2 × 109 cells/ml in pre-freezing extender; equilibration of diluted semen at 5°C, 20 vs 40 min; dimethylacetamide concentration, 6% vs 9%; dimethylacetamide equilibration time at 5°C, 1 vs 30 min; thawing at 60°C for 10 vs 50°C for 30 sec. Spermatozoa viability (EtBr exclusion procedure – stress test), mobility (Accudenz® swim-down test) and subjective motility were assessed in fresh and frozen-thawed semen.
3. The lower SWC (1.5 × 109 cells/ml) and the higher dimethylacetamide concentration (9%) had positive significant effects on the recovery rate of motile (22% vs 16%) and viable spermatozoa (39 vs 34%), respectively.
4.Membrane (SYBR14-PI staining) and DNA integrity (comet assay) were assessed before and after freezing/thawing according to the optimised protocol.
5. Recovery rates of spermatozoa with undamaged plasma membrane and DNA were 41% and 76%, respectively. The distribution of spermatozoa in classes of DNA damage was also analysed and discussed.
6. It was concluded that pellet cryopreservation was a damaging process mainly for plasma membrane rather than nuclear DNA in chicken spermatozoa. 相似文献
2. The rate of increase in deep‐body (rectal) temperature during exposure to 32°C was used as the index of thermoregulatory ability. Comb and foot surface temperatures were measured as indicators of peripheral vasomotor tone.
3. Because body temperature control depends on the balance between heat production and heat loss, heat production was measured to determine whether fat line hens had a higher heat production, which they would then have to dissipate.
4. During the first hour of heat exposure, rectal temperature in the ad libitum‐fed birds increased twice as rapidly as in the corresponding lean line sample and 6 times more rapidly than in the control‐fed fat‐line group.
5. Surface temperatures of comb and foot increased from 27°C to 37°C within the first hour at 32°C, with no effect of either genotype or feeding regimen on rate of increase.
6. Heat production was unrelated to genotype but was reduced by 23% by controlled feeding, largely because of the reduction in body weight.
7. The results demonstrated that ad libitum‐fed fat‐line birds are susceptible to heat stress and that this is related not to increased heat production, but to a decreased ability to lose heat. Elevation of blood viscosity by plasma triglycerides is suggested as a causal factor. 相似文献
2. The upper critical temperature (Tcu) was estimated by the air temperature at which: 1, respiratory frequency increased above 60 respirations/min and 2, body temperature increased by 0.3 °C above that at the lower critical temperature. These responses to the test temperatures were examined as a function of the. acclimatisation temperature (Ta) represented by the mean daily temperature during experimental periods.
3. A seasonal change in Tcu was observed, which correlated with Ta(r = 0.836). The seasonal 10 °C change in the Ta brought about a 3 °C change in Tcu, compared with an 8.5 °C change in the lower critical temperature.
4. Thermoneutral temperature zone decreased with increasing Ta; the two critical temperatures tended to merge at a Ta of 32 °C. The latter probably represents an upper limit for acclimatisation to heat. 相似文献
2. Myofibrils were prepared from 0.1 M and 0.2 M lactic acid marinated muscle and control (non‐marinated samples) sampled at 0, 1, 3, 7 and 14 d post mortem.
3. Changes in myofibril fragmentation index (MFI), myofibrillar proteins and Z‐line structure were examined.
4. Marination of duck breast muscle in lactic acid at 5°C enhanced fragmentation of myofibrils and degradation of myofibrillar proteins and Z‐line structure as compared to control samples.
5. In summary, lactic acid marination at 5°C can accelerate the post mortem degradation of myofibrils in Tsaiya duck breast muscle. 相似文献
2. Total duration of incubation was divided into setter (0 to 24 days) and hatcher (25 to 28 days) periods. Eggs transferred at the end of the setter period, (ET, % of fertile eggs) and hatching rate (HR, % of transferred eggs) were calculated, as well as the total hatching rate expressed as percentage of fertile eggs.
3. In the range 36 to 39°C, temperature affected significantly (P< 0.001) ET and HR, with optima at 37.2 and 37.0°C ± 0.1°C respectively.
4. During incubating period, relative humidity in the range 40 to 64% (water vapour partial pressure, Ph2o = 17 to 34 Torr at 36 to 39°C), significantly (P< 0.001) affected the total diffusive water loss and hatchling mass, both expressed as percentage of fresh egg mass. ET was significantly affected by water loss, the highest ET being for water loss of 13.3 ± 0.5%. Optimal relative humidity was calculated to be 48 to 52% (Ph2o = 23 to 25 Torr at 37.2°G).
5. The rate of inflowing air significantly (P< 0.001) affected HR, with an optimum at 3.1 Lstpd/(h . egg).
6. The age of the laying flock significantly (P< 0.001) increased water loss; this was explained by a parallel increase of the mass specific shell conductance to water vapour.
7. Finally optimum incubation conditions were deduced, giving total hatching rates of 78 to 81% of fertile eggs, improving by 5 to 8% the best results obtained routinely in commercial practice. 相似文献
2. A total of 3,000 fertile eggs from broiler breeders (Cobb®) were randomly divided into three incubation treatments: no ascorbic acid injection and egg incubation at 37.5°C (control); no ascorbic acid injection and egg incubation at 39°C; in ovo ascorbic acid injection prior to incubation (6 µg AA/100 µl water) and egg incubation at 39°C.
3. Male chicks hatched from the three incubation treatments were submitted to three distinct rearing temperatures (control, cold and hot) from the third week of age onwards (540 chicks were divided into 6 treatments with 5 replicates per treatment).
4. Measurements at 42 d showed that, after egg incubation at 39°C, the haematocrit, haemoglobin values, ionised calcium and glucose concentrations were increased and base excess values were reduced. However, in ovo injection of ascorbic acid normalised all these parameters.
5. Partial CO2 and O2 pressure were higher with increased rearing temperature. Blood pH was lower when eggs were incubated at 39°C and injected with ascorbic acid. In ovo injection of ascorbic acid induced leucocytosis due to lymphocytosis and heterophilia, restored basophils rate and led to monocytopoenia. Leucocytosis was triggered by hot rearing temperature due to lymphocytosis, eosinophilia and heterophilia.
6. The results obtained in this study showed that in ovo injection of ascorbic acid before incubation may serve as a long-term stimulator and modulator of the broiler immune system, and that high incubation temperatures induce adaptations in the electrolytic balance, minimising or avoiding the occurrence of respiratory alkalosis under hot rearing temperature. 相似文献
Received May 1, 2014; accepted August 10, 2014 相似文献
2. At Ta 32 °G there was no panting. At Ta 35 °G panting occurred without any increase in Tr but there was a slight alkalosis (pH 7.55).
3. At Ta 38 °G Tr increased and panting was accompanied by moderate alkalosis (pH 7.58).
4. At Ta 41 °G Tr increased considerably and severe alkalosis developed (pH 7.65).
5. From the relation between Tr , f and pH it is concluded that some degree of alkalosis is a normal response to panting in the laying hen. 相似文献
2. In experiment 1, aliquots of spermatozoa were stored in vitro in LS alone and LS containing 10%, 25%, 50% and 75% (v:v) PF for 0.5, 24, 48, 72, 96 and 120 h at 4°C. After the end of each storage period, spermatozoa were evaluated for their viability, mobility and penetrability. Viability was determined using SYBR-14 and propidium iodide (PI) staining. Mobility was assessed using an Accudenz assay. Penetrability was assessed using spermatozoa-inner perivitelline layer (IPL) interaction assay.
3. In experiment 2, aliquots of spermatozoa were stored in vitro in LS alone and LS containing 25% and 50% (v:v) PF for 0.5, 24, 48 and 72 h at 4°C, and then fertility of the spermatozoa was evaluated using intravaginal artificial insemination (AI) in hens.
4. Storage of spermatozoa in LS alone resulted in loss of viability, mobility, penetrability and fertility within 48 h. In contrast, no loss of viability and penetrability was observed for the spermatozoa stored for 48, 96, 72 and 48 h in LS containing 10%, 25%, 50% and 75% (v:v) PF, respectively. In particular, fertilising capacity was not lost for the spermatozoa stored in the presence of 25% or 50% PF in LS for 48 and 24 h, respectively.
5. In conclusion, these findings demonstrated that in vitro exposure of fowl spermatozoa to PF during hypothermic storage in LS prolonged spermatozoa survival. A 25% (v:v) level of inclusion of PF in LS may be effective for the improvement of viability, penetrability and fertilising ability of the stored spermatozoa. 相似文献
2. Cooling to 22°C for 24 h on days 14, 15, 16, 17 or 18 yielded similar results but cooling on day 13 increased late embryonic mortality.
3. When eggs were cooled to 22°C on day 16 of incubation there were no major differences in hatchability up to 48 h of cooling but chick quality deteriorated rapidly after 30 h and the limit for embryonic survival at this temperature was about 72 h.
4. There were no significant differences when eggs were cooled on day 16 and held for 24 h at 21.1, 23.9 or 26.7°C but hatchability and late deaths were significantly affected by cooling to 18.3°C. 相似文献
2. The muscle strips incubated at 0°C developed a peak isometric tension of 53.3 g/cm2. This occurred after only 17 min incubation when the pH was 7.02, demonstrating the potential of chicken PM muscle to cold shorten. Peak isometric tension at 5°C was considerably lower than that generated at 0°C. However, as this occurred when the muscle pH was still high (6.70), this also indicated some potential to cold shorten at 5°C.
3. At 10° to 30°C, the muscle strips developed mean peak isometric tensions of 18 g/cm2 after 6 h incubation by which time the muscle pH had fallen to 6.00, demonstrating a limited potential to rigor shorten. In contrast, those incubated at 40°C developed a peak tension of 54.5 g cm2 after 75 min when the muscle pH was also around 6.00, thus indicating the potential for intensive rigor shortening at this temperature. Incubation temperature and the resultant muscle pH therefore determine the potential of chicken PM muscle to either cold shorten or rigor shorten.
4. Despite the differences found in isometric tension profiles, cooked meat texture after isometric tension measurement was not significantly different at any of the temperatures studied primarily because the muscle strips were essentially prevented from shortening. 相似文献
2. DNA was extracted from 65 confirmed APEC E. coli from chicken, 100 presumptive commensal E. coli from healthy turkey and 35 from healthy chicken. Enterobacterial repetitive intergenic consensus PCR (ERIC-PCR) and virulence factors genotyping was performed to characterise genetic features.
3. Carbon source utilisation and antimicrobial susceptibility tests were performed to characterise phenotypic features of isolates.
4. The genetic divergence between E. coli strains tested by ERIC-PCR profiles and virulence-associated genes showed a clear genetic separation between E. coli APEC and turkey E. coli strains.
5. The carbon utilisation profile of turkey isolates was different from chicken and APEC strains; whereas antimicrobial susceptibility was highest for turkey isolates (53%), and lowest for APEC strains (33.8%).
6. The study showed a significant negative correlation between utilisation of arabitol and adonitol with different virulence determinants tested, which suggests that the ability to utilise some uncommon carbon sources may be used to discriminate between presumptive commensal E. coli and APEC. 相似文献
2. The mean initial microbial counts (log10 count/cm2) were 4·67, 4·14, 2·21, 2·78 and 2·96 for total aerobes, psychrotrophs, coliforms, Staphylococcus aureus and yeasts and moulds, respectively; these counts suggest a moderate level of contamination during processing.
3. Yeasts and moulds were present in relatively large numbers and constituted a considerable portion of the spoilage flora.
4. The mean shelf life of chicken broilers was 9·6, 6 and 4·4 d at 4, 7 and 10°C, respectively. Storage at 4°C resulted in better keeping than storage at 7°C or 10°C, while there was no significant difference between 7° and 10°C.
5. The initial totals of aerobes, psychrotrophs and yeasts and moulds were found to negatively correlate with shelf life. 相似文献