Assessing different liquid-storage temperatures for rooster spermatozoa

Arresting calcium-regulated sperm metabolic dynamics enables prolonged fertility in poultry liquid semen storage

The preservation of liquid semen is pivotal for both industrial livestock production and genetic management/conservation of species with sperm that are not highly cryo-tolerant. Nevertheless, with regard to poultry semen, even brief in vitro storage periods can lead to a notable decline in fertility, despite the in vivo capacity to maintain fertility for several weeks when within the hen's sperm storage tubules. For fertility in sperm, intracellular calcium ions ([Ca2+]i) play a key role in signaling towards modifying energy metabolism. While reducing [Ca2+]i has been found to enhance the preservation of sperm fertility in some mammals, the connection between semen fertility and calcium availability in avian sperm has received limited attention. In this study, we demonstrate that the use of extracellular and intracellular calcium chelators in liquid semen extenders, specifically EGTA and EGTA-AM, has distinct effects on prolonging the fertility of chicken sperm. These results were validated through in vivo fertility tests. Mechanistically, the effects observed were linked to coordination of mitochondrial metabolism and ATP catabolism. Despite both calcium chelators inducing hypoxia, they differentially regulated mitochondrial respiration and ATP accumulation. This regulation was closely linked to a bimodal control of dynein ATPase activity; a direct initial activation with reduction in [Ca2+]i, and subsequent suppression by cytoplasmic acidification caused by lactic acid. These findings not only contribute to advancing poultry liquid semen preservation techniques, but also elucidates biologically relevant mechanisms that may underlie storage within the female reproductive tract in birds.

L-arginine supplementation minimizes aging-induced changes in the sperm chromatin of roosters

Arginine is the main amino acid that constitutes the sperm protamine of roosters, named galline, which complexes with sperm DNA, allowing high compaction of its chromatin. Arginine supplementation has positive effects on semen quality in aged roosters, but this supplementation is not known to limit the progressive worsening of sperm chromatin compaction. This work aimed to verify whether L-arginine supplementation in the feed improve or maintain sperm chromatin quality since aging in roosters is usually accompanied by worsening chromatin quality. Four groups of 52-wk-old Ross AP95 lineage roosters were used, of which 6 semen samples per group were evaluated, totaling 24 samples. Another 24 samples, 6 per group, were evaluated after 6 wk of supplementation when one group was not supplemented (control) and the other 3 were supplemented with 1.15 kg (treatment 1), 2.17 kg (treatment 2), and 3.18 kg (treatment 3) of L-arginine/ton of feed. Computer image analysis of semen smears stained with toluidine blue pH 4.0 was used for sperm chromatin evaluation. Sperm chromatin was evaluated for compaction heterogeneity and compaction intensity by percentage decompaction relative to standard heads and by integrated optical density (IOD), which was used for the first time to identify sperm chromatin changes. Sperm head morphology was also evaluated by means of area and length. The IOD proved to be more efficient in identifying changes in rooster sperm chromatin compaction than the percentual decompaction. In general, chromatin compaction was positively influenced by the supplementation with L-arginine, being better in the supplementation with the highest levels tested. This was corroborated by the smaller average of the variables referring to the size of the spermatozoa heads of the animals that received feed with a higher content of L-arginine, since better compacted heads naturally tend to be smaller. Finally, arginine supplementation was able to limit or even improve sperm chromatin decompaction during the experimental period.

Methylene blue-mediated antimicrobial photodynamic therapy on chicken semen

BACKGROUND

Artificial insemination is widely employed in poultry, but high degrees of bacterial contamination are often observed in semen because of its passage through the cloaca. Consequently, most semen extenders for birds have antibiotics that could aggravate bacterial resistance.

METHODS

We evaluated the potential of antimicrobial photodynamic therapy (PDT) as an alternative to the use of antibiotics, and assessed whether changes in concentration and incubation time with methylene blue (MB), radiant exposure, and irradiance of light affect spermatozoa activity and bacteria in chicken semen.

RESULTS

Incubation with MB (< 25 µM) did not alter sperm motility, regardless of the pre-irradiation time (PIT, 1 or 5 min). Following 1 min of PIT with MB at 10 µM, samples were irradiated for 30, 60, 120, and 180 s at irradiances of 44, 29, and 17 mW/ cm² (660 nm LedBox). MB and light alone did not interfere with the analyzed parameters. However, when both factors were associated, increases in light dose led to greater reductions in sperm parameters, regardless of the irradiance used. Besides, PDT conditions that were less harmful to spermatozoa were not able to significantly reduce bacterial colonies in chicken semen.

CONCLUSIONS

A failure in MB selectivity could explain unsuccessful bacterial reduction following PDT. Further research involving other photosensitizers or conjugating molecules to MB to target microbial cells is needed for PDT application in poultry breeders.

Assessment of Sperm Viability and Computer-Assisted Motility Analysis in Budgerigars (Melopsittacus undulatus): Effect of Several In Vitro Processing Conditions

In order to preserve endangered psittacine species, more basic and applied research in reproductive biology is required. Assisted reproductive technologies such as artificial insemination play an important role in parrots species conservation programs to overcome the problem of infertile eggs and male infertility. The aim of this study was to define an effective in vitro protocol in order to standardize the sperm quality evaluation in psittacines, studying Melopsittacus undulatus as model species. Semen was collected from twenty adult males by massage technique from May to June. Sperm concentration was measured by the spectrophotometric method. Sperm quality (sperm membrane integrity (SMI), motility, and kinetic parameters) was assessed on fresh semen. Three different experimental protocols were performed to compare the effects of various processing conditions on SMI, motility, and kinetic parameters. In protocol 1, test was performed by Lake extender with three different pH, 7.4 versus 8.2 versus 8.4, and two different equilibration temperatures after dilution of fresh semen (4°C versus 25°C). In protocol 2, two dilution rates of semen after collection were valuated, 1 : 3 versus 1 : 4, as well as three different semen storage temperatures (4°C versus 25°C versus 38°C) before sperm motility analysis with the computer-assisted sperm analysis (CASA). In protocol 3, two different Makler chamber temperatures (38 versus 41°C) during motility analysis were tested. A significant progressive improvement in spermatozoa motility and kinetic parameters was registered with pH 8.4. Progressive motility and all kinetic parameters were higher at 4°C equilibration temperature. Straightness (STR) kinetic parameter was better with 1 : 4 dilution rate. Total motile sperm was higher in 41°C Makler chamber. In this study, for the first time, the effects of different processing protocols on psittacines seminal quality analysis were investigated. Significant differences conditioning the effectiveness of analysis protocols have been described.