Fiber characteristics of pork muscle exhibiting different levels of drip loss

The present study aimed to investigate the fiber characteristics of pork muscle exhibiting different levels of drip loss during storage. The samples were taken from Longissimus dorsi muscle to evaluate drip loss (n = 100). Fifteen muscles per group (low and high drip loss) were selected to evaluate the histological characteristics at 0 and 72 h of storage time. The statistical analysis revealed that a high drip loss group had greater endomysium thickness than a low drip loss group at 0 h of storage time (P < 0.05). There were no significant differences in total number of fibers, fiber diameter, fiber area and perimysium thickness at 0 h of storage time (P > 0.05). At 72 h of storage time, a high drip loss was evident in higher total number of fibers (P < 0.01), but smaller fiber diameter (P < 0.05), fiber area (P < 0.01) and endomysium thickness (P < 0.01) than a low drip loss group. There was no significant difference in perimysium thickness (P > 0.05). In conclusion, drip loss might be affected by muscle structural characteristics during storage.     

Expression level of the cytochrome P450c21 (CYP21) protein correlating to drip loss in pigs

Drip loss is an important meat quality trait of fresh meat affecting economic losses. The cytochrome P450c21 (CYP21) protein has a role on cortisol production and depends on stress. This might affect meat quality. The present study aimed to investigate the expression of CYP21 protein in correlation with drip loss. The samples were taken from the Longissimus dorsi muscle to evaluate drip loss (n = 300). Five muscles per group (low and high drip loss) were selected to evaluate CYP21 protein expression levels. Statistical analysis revealed that CYP21 protein expression levels were significantly difference between the drip loss groups. The high drip loss group had higher CYP21 protein expression levels than the low drip loss group (P < 0.05). Moreover, the high drip loss group had higher optical density values of the CYP21 protein band than the low drip loss group (P < 0.05). In conclusion, the expression of CYP21 protein will provide the basis for information and better understanding of the mechanisms related to drip loss in pork. Further study is warranted to validate these results in other populations.     

Seasonal variation in nuclear DNA integrity of frozen-thawed spermatozoa from Thai AI swamp buffaloes (Bubalus bubalis)

In this study, we investigated the susceptibility of frozen-thawed swamp buffalo sperm nuclear DNA to undergo controlled acid-induced denaturation in situ, as analysed by flow cytometry, and aimed to correlate the results with sperm head morphology over three seasons in tropical Thailand. Artificial insemination (AI) doses (n = 218) from 18 AI buffalo sires, prepared between 1980 and 1989 and 2003 and 2005, were tested and compared among three seasons, the rainy season, July-October; winter, November-February; and summer, March-June. The overall mean of DNA fragmentation index (DFI) (+/- SD) was 1.84 +/- 1.68%, range from 0.19 to 7.92%, with 0.221 +/- 0.021 of the x-DFI ranging from 0.190 to 0.350 and 0.023 +/- 0.009 of the SD-DFI ranging from 0.010 to 0.070. The DFI was consistently low (range 1.40 +/- 0.21% to 2.16 +/- 0.21%; LSM +/- SEM), with x-DFI ranging from 0.216 +/- 0.003 to 0.225 +/- 0.003 and SD-DFI ranging from 0.022 +/- 0.001 to 0.024 +/- 0.001 across the seasons. The DFI was low enough to be related to high fertility potential. However, DFI values varied statistically among seasons, being lower in the rainy season (1.40 +/- 0.21%, P < 0.05) than in winter (2.16 +/- 0.21%) or summer (2.00 +/- 0.20%), and were also affected by the year of semen collection and processing (P < 0.001). The proportion of morphologically abnormal sperm head shapes was low, with no significant differences between seasons. However, DFI was significantly related to the proportion of loose abnormal sperm heads (r = 0.27, P < 0.01). In conclusion, frozen-thawed swamp buffalo sperm chromatin integrity is not seriously damaged by cryopreservation or affected by the seasonal variations in temperature and humidity seen in tropical Thailand.     

Effects of supplementation of iodixanol to semen extender on quality and fertilization ability of frozen–thawed Thai native bull sperm

This study investigates the effects of iodixanol supplementation in varied concentrations to Tris egg yolk (TEY) extender on the quality and fertilization ability of frozen–thawed sperm of Thai native bulls. Each ejaculate was divided into four different groups, as follows: sperm were treated with TEY extender (control group) and TEY extender supplemented with three different concentrations of iodixanol (1.25%, 2.50% and 5.00%). Semen straws were frozen in liquid nitrogen vapor. After thawing, sperm motility characteristics, viability, plasma membrane integrity and acrosome integrity were determined. Also, frozen–thawed spermatozoa from all groups were used for in vitro fertilization and artificial insemination (AI) in natural estrus Thai native cows. The results showed that the post‐thaw quality of the 2.50% iodixanol group was superior to the other iodixanol groups (P < 0.05). However, iodixanol had no beneficial effect on post‐thaw sperm in vitro fertilization ability and pregnancy rate after AI (P > 0.05). It can be concluded that the supplementation of 2.50% iodixanol extender significantly improves the progressive motility, viability, plasma membrane integrity and acrosome integrity of cryopreserved semen from Thai native bulls, but it has no beneficial effect on in vitro fertilization ability and pregnancy rate after AI.