The next generation sequencing has significantly contributed to clarify the genome structure of many species of zootechnical interest. However, to date, some portions of the genome, especially those linked to a heterogametic nature such as the Y chromosome, are difficult to assemble and many gaps are still present. It is well known that the fluorescence in situ hybridization (FISH) is an excellent tool for identifying genes unequivocably mapped on chromosomes. Therefore, FISH can contribute to the localization of unplaced genome sequences, as well as to correct assembly errors generated by comparative bioinformatics. To this end, it is necessary to have starting points; therefore, in this study, we reviewed the physically mapped genes on the Y chromosome of cattle, buffalo, sheep, goats, pigs, horses and alpacas. A total of 208 loci were currently mapped by FISH. 89 were located in the malespecific region of the Y chromosome (MSY) and 119 were identified in the pseudoautosomal region (PAR). The loci reported in MSY and PAR were respectively: 18 and 25 in Bos taurus, 5 and 7 in Bubalus bubalis, 5 and 24 in Ovis aries, 5 and 19 in Capra hircus, 10 and 16 in Sus scrofa, 46 and 18 in Equus caballus. While in Vicugna pacos only 10 loci are reported in the PAR region. The correct knowledge and assembly of all genome sequences, including those of genes mapped on the Y chromosome, will help to elucidate their biological processes, as well as to discover and exploit potentially epistasis effects useful for selection breeding programs.

A wide range of mammalian hybrids has recently been found by chance or through population-screening programs, but studies about their fertilizing capacity remain scarce and incomplete. Most of them are assumed to be sterile due to meiotic arrest caused by the failure of chromosome pairings. In this study, we evaluated both sperm meiotic segregation, by 2D fluorescent in situ hybridization (FISH) analysis, and sperm quality (Sperm Chromatin Structure Assay) by flow cytometer in a fertile boar–pig hybrid (2n = 37,XY) originating from a Nero Siciliano pig breed (Sus scrofa domesticus) and a wild boar (Sus scrofa ferus). Spermatozoa were also separated by a dual-layer (75–60%) discontinuous Percoll gradient, resulting in two fractions with a significantly better overall quality in the motile sperm fraction. These data were confirmed by FISH analysis also, where the frequencies of spermatozoa with a regular chromosome composition were 27% in total sperm fraction and 64% in motile sperm fraction. We also evaluated the nuclear architecture in all counted spermatozoa, showing a chromatin distribution changing when chromosome abnormalities occur. Our results demonstrate that the chromosome pairing has a minimal effect on the sperm segregation and semen quality of a boar–pig hybrid, making it fertile and harmful for the conservation of autochthonous pig breeds.

Background/Objectives: Insect-derived lipids are emerging as circular-economy feed ingredients, but their implementation in ruminant diets requires robust safety assessment beyond productive endpoints. This study evaluated genome integrity in 26 lactating Valdostana Red Pied cows fed concentrates containing either hydrogenated palm fat (HPF; n = 13) or black soldier fly oil (Hermetia illucens oil, HIO; n = 13) for 50 days. Methods: Peripheral blood lymphocytes were analyzed using Sister Chromatid Exchanges (SCE), reflecting replication-associated chromosomal instability, and the alkaline Comet assay, quantifying primary DNA damage at the single-cell level (Tail DNA and Olive tail moment) at T0 (the day before the start of the two experimental diets), T1 (30 d) and T2 (50 d). Results: Baseline SCE frequencies were comparable between groups. Over time, SCE values decreased in both groups, but a significant reduction occurred only in HIO at day 50, with lower SCE frequency than HPF (5.73 ± 0.11 vs. 6.29 ± 0.13; p = 0.002). Comet tail DNA showed a significant time effect (T0 vs. T1: mean difference = 179,846.6; p < 0.001; T0 vs. T2: mean difference = 138,395.2; p = 0.012), with diet-dependent modulation. In fact, in HIO, tail DNA decreased from 387,886 ± 94,606 (T0) to 147,006 ± 30,592 (T1; p < 0.001), remained lower at day 50 (155,723 ± 29,357; p = 0.024), and was lower than HPF at both T1 (p = 0.006) and T2 (p = 0.009). Olive tail moment also decreased over time (T0 vs. T1: mean difference = 1.925 × 10¹⁵; p = 0.008; T0 vs. T2: mean difference = 1.676 × 10¹⁵; p = 0.025), and it differed between diets at day 50 in favor of HIO (5.99 × 10¹⁵ ± 5.45 × 10¹⁴ vs. 7.26 × 10¹⁵ ± 5.98 × 10¹⁴; p = 0.017). Conclusions: Overall, no evidence of genotoxicity was observed in cows fed HIO; conversely, the results support compatibility with genome stability and suggest a modest time-dependent improvement detectable mainly after prolonged supplementation.

In Italy, karyotype analysis is routinely performed on all young males intended for reproduction to screen for chromosome abnormalities. This practice gained prominence following the identification of a complex chromosome abnormality in a well-known bull named Magnifico and its progeny. This procedure significantly enhances the value of the Mediterranean Italian River Buffalo breed, particularly in the context of artificial insemination both within Italy and in other countries importing semen. In the current study, 159 young Mediterranean Italian River Buffalo (MIRB) males intended for reproduction, 30 females with fertility issues, 3 young females and a male co-twin were investigated by analyzing their karyotype using both CBA- and RBA-banding. All males displayed a normal karyotype (2n = 50, XY), although one animal displayed an abnormal X-chromosome with C-band polymorphism, as it is C-band negative when this chromosome normally shows the largest C-band among all chromosomes. This result was also confirmed by the FISH-mapping technique using three bovine BAC-clones containing SAT-I, SAT-III and SAT-IV. Cytogenetic investigation showed that seven females, along with one male co-twin, were affected by freemartinism (XX/XY leukocyte chimerism) and were subsequently removed from the farm. In two of these females, clinical and necroscopic examinations showed severe damage of the internal reproductive organs.