Relationship between Iberian ibex (Capra pyrenaica) sperm quality and level of parasitism

Cryopreservation Strategies for Poultry Semen: A Comprehensive Review of Techniques and Applications

Poultry semen preservation is crucial for sustaining genetic diversity, improving production efficiency, and facilitating various breeding initiatives. This review underscores the importance and challenges associated with different preservation techniques. We investigate effective techniques for semen collection and evaluation, focusing on vital parameters such as volume, concentration, motility, and morphology. Preservation strategies are categorized into short-term approaches, such as dilution with extenders, and mid-to-long-term strategies, like freezing and the use of cryoprotectants. Additionally, we explore several factors affecting semen quality, including male age and genetics, seasonal impacts, and stress during handling. Assessing the quality of preserved semen is critical, particularly regarding post-thaw motility. The applications of these preservation techniques in artificial insemination, genetic enhancement, the conservation of endangered breeds, and biobanking are highlighted. This review identifies critical research opportunities, including the development of improved cryoprotectants, refining freezing protocols, comprehending the mechanisms of semen damage, and innovating novel preservation technologies. Addressing these challenges will enhance poultry semen preservation and contribute to sustainable poultry farming.

Comparative survey of gastrointestinal parasites in sympatric Iberian ibex (Capra pyrenaica) and domestic goats using molecular host specific identification

An isolated population of several hundred Iberian ibex (Capra pyrenaica) inhabits the Gerês-Xurés Transboundary Biosphere Reserve (GXTBR) in north-western Iberian Peninsula, in partial sympatry with tens of thousands domestic goats (Capra hircus). This study aimed to assess the prevalence and shedding intensity of gastrointestinal parasites from sympatric herds of domestic goat and Iberian ibex in autumn 2018. A total of 93 pooled faecal samples were collected from GXTBR (39 from domestic goats and 54 from Iberian ibex) and the host species was identified using molecular techniques, whenever defecation was not visualised in the field. Parasitological analysis was achieved by joint Willis flotation/sedimentation, McMaster and Mini-FLOTAC techniques. Seventy-two samples (25 domestic goats and 47 Iberian ibex) were retained for analysis after discarding the least fresh and those with uncertain specific identification. Generalized linear mixed models compared prevalence and shedding intensity between caprine species. Domestic goats showed a non-significant tendency to be more parasitized than Iberian ibex, as assessed by overall prevalence (100.0%, CI₉₅ 86.7-100.0 vs. 74.5%, CI₉₅ 69.5-84.8), and shedding intensity. This study reveals a similar community of gastrointestinal parasites in an abundant livestock species and an isolated population of wild caprine, living in partial sympatry. It is the first study on the health status of this endangered Iberian ibex population, in close contact with livestock, highlighting the need for further sanitary surveillance.

COMPARISON OF MODIFIED FLOTAC AND BAERMANN TECHNIQUES FOR QUANTIFYING LUNGWORM LARVAE IN FREE-RANGING BIGHORN SHEEP (OVIS CANADENSIS) FECES, MONTANA, USA

Lungworms are important parasites of wildlife and host infection status is often evaluated using coprologic techniques, most commonly the Baermann method. Recently, the FLOTAC® has emerged as a new tool for diagnosing lungworm infections, and methodologic comparison studies in domestic species suggest that this method outperforms many other established techniques. We compared a modified FLOTAC with the beaker-modified (bm)-Baermann to evaluate the relative performance of the two techniques for counting lungworm larvae in bighorn sheep (Ovis canadensis) feces. Both methods generated equivalent larval counts and both were highly repeatable. The major difference between the two methods was that the FLOTAC was poorer at detecting mixed infections. The ultimate choice between using the FLOTAC and bm-Baermann methods for quantifying lungworm larvae in wildlife studies may depend on the specific nature of the research questions being addressed, balanced by practical constraints.

Sex-specific selection for MHC variability in Alpine chamois

Background

In mammals, males typically have shorter lives than females. This difference is thought to be due to behavioural traits which enhance competitive abilities, and hence male reproductive success, but impair survival. Furthermore, in many species males usually show higher parasite burden than females. Consequently, the intensity of selection for genetic factors which reduce susceptibility to pathogens may differ between sexes. High variability at the major histocompatibility complex (MHC) genes is believed to be advantageous for detecting and combating the range of infectious agents present in the environment. Increased heterozygosity at these immune genes is expected to be important for individual longevity. However, whether males in natural populations benefit more from MHC heterozygosity than females has rarely been investigated. We investigated this question in a long-term study of free-living Alpine chamois (Rupicapra rupicapra), a polygynous mountain ungulate.

Results

Here we show that male chamois survive significantly (P = 0.022) longer if heterozygous at the MHC class II DRB locus, whereas females do not. Improved survival of males was not a result of heterozygote advantage per se, as background heterozygosity (estimated across twelve microsatellite loci) did not change significantly with age. Furthermore, reproductively active males depleted their body fat reserves earlier than females leading to significantly impaired survival rates in this sex (P < 0.008). This sex-difference was even more pronounced in areas affected by scabies, a severe parasitosis, as reproductively active males were less likely to survive than females. However, we did not find evidence for a survival advantage associated with specific MHC alleles in areas affected by scabies.

Conclusions

Increased MHC class II DRB heterozygosity with age in males, suggests that MHC heterozygous males survive longer than homozygotes. Reproductively active males appear to be less likely to survive than females most likely because of the energetic challenge of the winter rut, accompanied by earlier depletion of their body fat stores, and a generally higher parasite burden. This scenario renders the MHC-mediated immune response more important for males than for females, which implies a relatively stronger selection pressure on MHC genes in males than in females.

Negative effect of the arthropod parasite, Sarcoptes scabiei, on testes mass in Iberian ibex, Capra pyrenaica

Testes mass is a key factor in male reproductive success and is potentially exposed to so-called 'parasitic castration'. This is the result of the direct destruction or alteration of reproductive cell lineages (parasitic castration sensu stricto), or the indirect detrimental effects - for example, via body condition - on the ability of progenitors to produce or rear offspring (parasitic castration sensu lato). There are enormous gaps in our knowledge on the effects of parasites on the testes of wild mammals and in an attempt to rectify this dearth of data we examined the relationship between the skin parasite Sarcoptes scabiei and testes mass in Iberian ibex Capra pyrenaica. We considered data from 222 males that were culled in the population from the Sierra Nevada in Spain. Our results provide evidence that sarcoptic mange is associated with reduced size-corrected testes mass in Iberian ibex which supports the hypothesis that parasitism is a determining factor in gonad plasticity in male mammals. We discuss several hypothetical causes of this relationship and highlight the need to deepen the sub-lethal effects of pathogens if we are to accurately understand their modulator effects on host population dynamics.