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LA CRIOCONSERVAZIONE DEL MATERIALE SEMINALE NELLA SPECIE GALLUS GALLUS
Full text linkIn the last 50 years, great changes occurred in Italy in poultry production. Local breeds were abandoned and high performing genetic hybrids spread by few industries. The globalization of poultry trade led to a worldwide loss of avian genetic resources . The indigenous breeds survived by fancy breeders, and conservation programs are required to preserve them. One of the most important step in a conservation program is to create a cryobank of genetic resources. For avian species, the most feasible way to preserve gametes is cryopreservation of semen. Researches in this field started in the late Fifties and were soon abandoned because of the bad quality of semen after freezing/thawing procedure. In 1995, Tselutin published a protocol to freeze avian semen, obtaining the same fertility rate than fresh semen. This procedure, consisting in few simple steps, was based on the initial dilution of semen and a first equilibration time at 5°C, addition of DMA as cryoprotectant and a very fast second equilibration time, then dropping semen directly in a liquid nitrogen bath to form frozen semen pellets, finally thawing at high temperature for few seconds.
On the basis of Tselutin’s procedure, the aim of this thesis was to set the best conditions to cryopreserve semen of the Italian endangered local breed Mericanel della Brianza, and of the commercial Hubbard meat type strain.
The four experiments described in this work focused on the study of the most performing conditions of the cryopreservation procedure for semen from the two genetic lines chosen. Semen quality of MdB and Hubbard roosters was studied soon after collection and after freezing/thawing in experiment 1 and 2. Semen quality was tested in cryopreserved semen through the evaluation of viability, motility, mitochondria status and DNA fragmentation. In vivo fertility of cryopreserved semen from Hubbard males was evaluated through heterologous in protocol 2. The sensitivity to cryopreservation of semen according to the initial quality was studied in protocol 4; viability and motility were considered to assess sperm quality
Biological monitoring of occupational exposure to cyclohexane by urinary 1,2- and 1,4-cyclohexanediol determination.
No full textPellet cryopreservation for chicken semen : effects of sperm working concentration, cryoprotectant concentration, and equilibration time during in vitro processing
No full textThe aim of the study was to standardize the pellet cryopreservation procedure for chicken semen. Mericanel della Brianza male chicken breeders (Italian breed) were used. Pooled semen samples were processed according to the following conditions: (1) dilution in prefreezing extender to 1 versus 1.5 bill cells/mL sperm working concentration (SWC); (2) 6% versus 9% dimethyl acetamide (DMA) concentration (DMAco); (3) 1 versus 30minutes DMA equilibration (DMAeq) at 4°C. Sperm viability and motility were assessed in semen (four replicates/treatment) soon after collection (time 0), after DMAeq (time D), and after freezing/thawing (time FT). The recovery rates (%) of viable and motile sperm after freezing/thawing were also calculated. The low SWC (1 bill/mL) and the low DMAco (6%) indicated a positive significant effect on the proportion of motile sperm (1 bill/mL=53% vs. 1.5 bill/mL=48%; 6% DMA=55% vs. 9% DMA=47%). Very short DMAeq (1minute) did not significantly change sperm viability during processing (from time 0 to time D) before freezing whatever the DMAco, and, in contrast, the longer DMAeq showed a significant negative effect on sperm viability. The highest proportion of motile sperm was recorded in semen samples diluted to 1 bill/mL and added with 6% DMA; in this condition, DMAeq had no effect (57% 1minute and 61% 30minutes). Increasing SWC to 1.5 bill/mL and adding again 6% DMA, a significant effect of DMAeq was observed, and the higher proportion of motile sperm (58% vs. 43%) was recorded after 1minute DMAeq. A general decrease in sperm motility was shown in semen samples with 9% DMA (47% vs. 55%), and different conditions in SWC and DMAeq were not effective in the prevention of such decrease
Egg related parameters affecting fertility and hatchability in the Italian bantam breed Mericanel della Brianza
No full textLocal chicken breeds are a vital reservoir of gene resources and their conservation has a technical role related to the future development of the productive system, as well as a social-cultural role. The aim of this study was to evaluate the effects of egg weight, egg storage period and egg weight loss on hatchability of fertile eggs in the Italian bantam breed Mericanel della Brianza. Fourteen females and eight males were kept in floor pens and divided in 8 families (1M:1 or 2F) during the reproductive season (March–June). Birds received a photoperiod of 14L:10D and were fed ad libitum. Egg production and egg weight were recorded daily. Eggs were divided in 4 weight groups: EW1=25%. Fertility, embryo mortality and hatchability were recorded. The mean values during the reproductive season were 82% fertility and 50% hatchability of fertile eggs. The best combination of fertility and hatchability values were recorded in EW2 and lower fertility was recorded in EW1 (P<0.05). Hatchability decreased under 50% after 10 day storage period before incubation and the best hatchability was recorded in EWL1. The present results contribute to the knowledge on reproductive parameters necessary to improve the reproductive efficiency of this Italian breed within a conservation plan
Sperm quality changes during equilibration time at 4 °C before cryopreservation of chicken semen
No full textCryopreservation procedure includes many steps and each one may affect sperm quality and then sperm viability after thawing. The aim of our experiment was to study if sperm quality changes occur during the initial steps of the cryopreservation pellet procedure in chicken semen. The initial steps, dilution rate and equilibration time at 4 °C, were studied. Ejaculates were collected from Mericanel della Brianza male breeders (n. 18), pooled and splitted into two aliquots, one diluted 1:2 and the other one 1:3 in prefreezing Lake’s diluent. Diluted aliquots were equilibrated at 4 °C for 40 minutes. The following semen parameters were measured on fresh semen (T0), after 20 (T20) and 40 (T40) minutes: motility (%), VCL (μm/sec), VSL (μm/sec), LIN (%), ALH (μm), normal and abnormal viable sperm, dead sperm and damaged sperm (%). The main effects, dilution rate and equilibration time, and the relative interaction were studied by repeated measure analysis of variance. Sperm quality was significantly affected by the equilibration time, whereas the dilution rate and the interaction were not significant. The proportion of abnormal viable sperm significantly increased from T0 to T20 (15 to 21%). Other changes occurred from T20 to T40: the proportion of viable normal sperm significantly decreased compared to T0 (69 to 62%), and the VCL (131 to 119 μm/sec) and ALH (11 to 9 μm) values also significantly decreased. No further decrease in the proportion of abnormal viable sperm from T20 to T40 was recorded. Very similar trend in sperm quality was found with both dilutions during equilibration time at 4 °C. The variability found in semen concentration among ejaculates suggests the need to improve the criteria of dilution to standardize semen processing. In conclusion, short equilibration time, such as 20 minutes, in prefreezing diluent at 4 °C is recommended to prevent a decrease in sperm quality during chicken semen processing for cryopreservation
Chicken sperm cryopreservation by pellet method : effect of drop volume and thawing procedure
No full textChicken sperm cryopreservation by the pellet method : study on sperm working concentration
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