This paper explores the head-on collision between two-counter propagating positron acoustic solitons and double layers (DLs) in an unmagnetized collisionless plasma having mobile cold positrons fluid, immobile positive ions and ($$r,\;q$$ r , q )-distributed hot positrons, and hot electrons. By employing the extended Poincaré–Lighthill–Kuo method, the coupled Korteweg–de Vries (KdV), modified KdV (mKdV) and Gardner equations are derived to archive this goal. The effect of dimensionless parameters on the propagation characteristics of interacting KdV solitons (KdVSs), mKdV solitons (mKdVSs), Gardner solitons (GSs) and DLs are examined in detail by considering the limiting cases of ($$r,\;q$$ r , q )-distribution. It is noted that the interaction of GSs and DLs are reported for the first time. The outcomes might be comprehended and beneficial not only in space and astrophysical environments but also in laboratory studies.

The present study was conducted to analyze the fresh and post-thaw semen quality and fertility from native bulls of Red Chittagong Cattle (RCC), BLRI Cattle Breed 1 (BCB1), and Munshiganj Cattle of Bangladesh. One hundred and seventy-two ejaculates were collected by artificial vagina set and semen analysis was performed using Computer Assisted Sperm Analyzer (CASA) at Bangladesh Livestock Research Institute. Commercial extender (AndroMed) was used to dilute the fresh semen. After equilibration (4˚C for 4 hr), freezing was done using a programmable bio-freezer. Post-thawed semen was evaluated for sperm motility and kinematics. Cryopreserved semen straws were used for artificial insemination (AI) and determined the bull fertility based on 60 days non-return rate. Motility of the sperm differs significantly (p < 0.01) among the genotypes. Total motility was higher in Munshiganj bulls and static motility was higher in BCB1 bulls. However, the semen volume and sperm concentration did not vary significantly (p > 0.05) among the bulls but the highest concentration was found in Munshiganj bull (1669.60 ± 192.07 million/ml) followed by RCC (1648.70 ± 91.07 million/ml) and BCB1 bull (1481.60 ± 167.35 million/ml). Moreover, the highest bent tail (5.89 ± 0.75%), coiled tail (1.01% ± 0.22%) and distal mid-piece reflex (2.26% ± 0.28%) were observed in BCB1 followed by Munshiganj and RCC. Amplitude of lateral head displacement (ALH) was recorded higher in post-thaw than in fresh semen. Kinematics parameters of post-thaw semen decreased than fresh semen irrespective of genotypes. More number of doses/ejaculates can be produced from Munshiganj bull (394.34 ± 127.95) followed by RCC (349.01 ± 120.91

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