Breeding Conditions Research Articles

Responses of Bird Communities to Habitat Structure along an Aridity Gradient in the Steppes North of the Sahara

We explored the influence of habitat structure on bird density and species richness in the poorly known bird communities in the steppes of Eastern Morocco, along a 200 km long N–S gradient of increasing aridity. The birds were surveyed, and habitat structure was measured in 44 transects regularly distributed along the gradient and during the winter and spring seasons in two consecutive years. After applying a principal component analysis (PCA), five axes were identified, including one related to the latitude–altitude–soil-type gradient and another describing the development of herbaceous vegetation. Generalized linear models were used to explore the relations between bird density and species richness with PCA axes in each season, considering both the entire community and groups of granivorous, insectivorous, and mixed-diet species. More than 90% of the birds were year-round residents, with larks dominating the community in both seasons. We conclude that a distinct multifactorial response can be identified for each functional group of species. In the winter, the community is mainly affected by the structure of the habitat, while aridity (and its assumed relation to primary production) is less influential. In the spring, habitat structure continues to have the greatest explanatory power, but location along the aridity gradient becomes more relevant. These findings reveal the interaction of the negative effects of climatic and anthropogenic changes in the habitat available to these bird communities, with a greater impact expected on birds with diets that include seeds, as well as a general shift of optimal breeding conditions toward more northerly latitudes.

Four nesting attempts of a Great Bustard Otis tarda female in one reproductive season

Abstract A mature Great Bustard (Otis tarda) female tagged with a satellite transmitter in Dévaványa made four breeding attempts in 2019. A total of seven eggs were laid on the four occasions. None of the breeding attempts were successful, and the bird was killed by a predator, presumably a Red Fox (Vulpes vulpes), during the fourth breeding attempt. The four egg-laying attempts are a new experience in the reproductive biology of the species. The failure of the nestings and the death of the bird itself confirm that the conservation measures of the species, as emphasised in international and national conservation plans – controlling predators and egg predator populations, ensuring undisturbed breeding conditions – are important conservation biology actions serving for the protection of the species.

Nest Change and Individual Fitness in a Scopoli’s Shearwater Population: A Capture-Recapture Multistate Analysis

Seabirds are compelled to nest on land, away from their feeding areas, which they can only reach by leaving eggs or chicks in the nest, often for long periods of time. For this reason, almost all of them have evolved social monogamy as a reproductive system, cooperation between partners for incubation and chick rearing, and long-lasting pair bonds. Additionally, nesting conditions are essential for successful reproduction, and the nest can be considered a resource if it provides more guarantees in this aspect. As a result, the nest may be a source of contention and intraspecific competition, especially among males. In this work, we analyze long-term data of the Scopoli’s shearwater (Calonectris diomedea) population to address the fitness consequences of nest change regarding survival and reproductive success. We used capture–recapture multistate models and the AICc model selection approach to test three hypotheses: breeding failure triggers nest change; nest change affects breeding success probability; nest change affects survival. Each year, about 5% of the breeders move to a new nest. For males, it was mainly a way to improve their breeding conditions and was observed in their early years as a breeder. Conversely, for females, it was a way to improve their reproductive performance by trying with a new mate after a failure. Males that changed nests improved their breeding success probability. Instead, in females, there was no causal relation between nest change and breeding success, the latter having been more influenced by the intrinsic quality of the female as a breeder. We did not even find a link between nest change and survival. Instead, we demonstrated that reproductive failure could affect the apparent survival of females, probably because it induces breeding dispersal.

Assessment of the Physiological Values and the Reference Histological Profile Related to Sex Steroids in Veal Calves

Among forbidden substances included in the European Union legislation, endogenous steroids constitute a challenge in the framework of veterinary Official Monitoring Plans. They can be naturally present in body fluids at variable levels depending on the species, sex and age of the animals. Considering the significant advances achieved in breeding conditions and in the selection of producing traits in meat cattle, the aim of this study was to verify by analytical method, in veal calves housed under controlled conditions, if the level of natural steroids hormones assumed as physiological are still actual. The second aim of the study was to verify if the normal histological pattern of growth promoters in target organs is influenced accordingly. Bovine male sex organs are currently analysed in the frame of the Italian histological plan to monitor illicit treatments trend, highlighting microscopic, induced alterations. The levels of 17β-estradiol and progesterone residues resulted under the Limit of Quantitation of the approved official methods and the level of testosterone resulted below the level stated in the Italian Ministerial Decree in force. Male target organs appeared within the limits of the standard histological features.

Predicting Animal Welfare Labels from Pork Fat Using Raman Spectroscopy and Chemometrics

The awareness of the origin of meat that people consume is rapidly increasing today and with that increases the demand for fast and accurate methods for its distinction. In this work, we present for the first time the application of Raman spectroscopy using a portable spectrometer for the classification of pork. Breeding conditions were distinguished from spectral differences of adipose tissues. The pork samples were obtained from Dutch vendors, from supermarkets with quality marks of 1 and 3 stars, and from a local butcher shop. In total, 60 fat samples were examined using a fiber-optic-coupled Raman spectrometer. Recorded spectra were preprocessed before being subjected to multivariate statistical analysis. An initial data exploration using Principal Component Analysis (PCA) revealed a separation of adipose tissue samples between the lower supermarket quality grade and the samples from the local butcher. Moreover, predictive modeling using Partial Least Squares Discriminant Analysis (PLS-DA) resulted in 96.67% classification accuracy for all three sources, demonstrating the suitability of the presented method for intraspecies meat classification and the potential on-site use.

Evaluating the use of statistical and machine learning methods for estimating breed composition of purebred and crossbred animals in thirteen cattle breeds using genomic information.

Introduction: The ability to accurately predict breed composition using genomic information has many potential uses including increasing the accuracy of genetic evaluations, optimising mating plans and as a parameter for genotype quality control. The objective of the present study was to use a database of genotyped purebred and crossbred cattle to compare breed composition predictions using a freely available software, Admixture, with those from a single nucleotide polymorphism Best Linear Unbiased Prediction (SNP-BLUP) approach; a supplementary objective was to determine the accuracy and general robustness of low-density genotype panels for predicting breed composition. Methods: All animals had genotype information on 49,213 autosomal single nucleotide polymorphism (SNPs). Thirteen breeds were included in the analysis and 500 purebred animals per breed were used to establish the breed training populations. Accuracy of breed composition prediction was determined using a separate validation population of 3,146 verified purebred and 4,330 two and three-way crossbred cattle. Results: When all 49,213 autosomal SNPs were used for breed prediction, a minimal absolute mean difference of 0.04 between Admixture vs. SNP-BLUP breed predictions was evident. For crossbreds, the average absolute difference in breed prediction estimates generated using SNP-BLUP and Admixture was 0.068 with a root mean square error of 0.08. Breed predictions from low-density SNP panels were generated using both SNP-BLUP and Admixture and compared to breed prediction estimates using all 49,213 SNPs (representing the gold standard). Breed composition estimates of crossbreds required more SNPs than predicting the breed composition of purebreds. SNP-BLUP required ≥3,000 SNPs to predict crossbred breed composition, but only 2,000 SNPs were required to predict purebred breed status. The absolute mean (standard deviation) difference across all panels <2,000 SNPs was 0.091 (0.054) and 0.315 (0.316) when predicting the breed composition of all animals using Admixture and SNP-BLUP, respectively compared to the gold standard prediction. Discussion: Nevertheless, a negligible absolute mean (standard deviation) difference of 0.009 (0.123) in breed prediction existed between SNP-BLUP and Admixture once ≥3,000 SNPs were considered, indicating that the prediction of breed composition could be readily integrated into SNP-BLUP pipelines used for genomic evaluations thereby avoiding the necessity for a stand-alone software.

Polymorphic variants of the CD62L and ACSL1 genes in connection with the resistance of cows to mastitis

Relevance. In conditions of intensive dairy cattle breeding, the incidence of cows with mastitis continues to be an urgent problem. The number of somatic cells (CCCs) in milk is a breeding indicator for improving the health of the mammary gland of cows. The study of animal resistance to the disease, which is based, among other things, on the genetic component, will make it possible to increase the efficiency of breeding in the future. The purpose of this work is a comparative analysis of the relationship of polymorphic variants of the ACS L1 (rs208522533) and CD62L (rs41803917 and rs41803917) genes with indicators of milk productivity and the level of somatic cells in the milk of Ayrshire cows.Methods. A sample of first-calf cows of Ayrshire breed (n = 191) belonging to one of the breeding farms of the Leningrad region was formed. Animal genotypes were determined by PCR-PDRF. Analysis of the genotype frequency by rs208522533 of the ACS LI gene showed that 99% of the animals were carriers of the GG genotype.Results. The results of studies of the CD62L gene showed that rs41803917 determined a high frequency of the G allele (80.4%) and on average more than 60% of animals had the GG genotype. rs109966956 of the CD62L gene revealed a high frequency of the C allele (80.1%) and 64.9% of the animals had the CC genotype. High values of BOX PC were established in small groups of animals with the AA genotype according to rs41803917 (p £ 0.05) and the TT genotype according to rs109966956 (p £ 0.001). Individuals with the AG genotype according to rs41803917 of the CD62L gene had high protein percentages (p £ 0.05) and low BSC (p £ 0.05). The results obtained indicate that SNPs rs41803917 and rs41803917 of the CD62L gene can be considered as potential markers of resistance to mastitis in Ayrshire cows.

Optimizing Honey Bee Drone Rearing: An Examination of Colony Management Techniques and Their Impact on Sperm Quality

The vitality, ejaculation success, sperm quantity, sperm viability and motility directly depends on the breeding conditions of the honey bee drones because since the egg stage, both the larva and the adult drones are fully taken care of by the worker bees. Worker bees choose to care for and feed drone brood only during the season when mating of virgin queen bees takes place in nature. If there is a lack of food resources in the bee colony, the worker bees can decide not to feed both the drone larvae and adult drones and throw them out of the nest. In this field study, the various methods of preparation of drone rearing colonies are reviewed and tested: in the presence of a queen and without one, with an additional feed base (sugar syrup, honey, pollen), various sizes of colonies, etc. Drones were reared in these colonies, then their sperm were collected and sperm motility, viability, cell concentration and sperm quantity per drone were determined. In addition to that, authors also evaluated the parameters characterizing the quality of sperm in different races of honey bee drones.

Multiple and Consecutive Genome Editing Using i-GONAD and Breeding Enrichment Facilitates the Production of Genetically Modified Mice.

Genetically modified (GM) mice are essential tools in biomedical research. Traditional methods for generating GM mice are expensive and require specialized personnel and equipment. The use of clustered regularly interspaced short palindromic repeats (CRISPR) coupled with improved-Genome editing via Oviductal Nucleic Acids Delivery (i-GONAD) has highly increased the feasibility of producing GM mice in research laboratories. However, genetic modification in inbred mouse strains of interest such as C57BL/6 (B6) is still challenging because of their low fertility and embryo fragility. We have successfully generated multiple novel GM mouse strains in the B6 background while attempting to optimize i-GONAD. We found that i-GONAD reduced the litter size in superovulated pregnant females but did not impact pregnancy rates. Natural mating or low-hormone dose did not increase the low fertility rate observed in superovulated B6 females. However, diet enrichment had a positive effect on pregnancy success. We also optimized breeding conditions to increase the survival of small litters by co-housing i-GONAD-treated pregnant B6 females with synchronized pregnant FVB/NJ companion mothers. Thus, GM mice generation was increased by an enriched diet and shared pup rearing with highly fertile females such as FVB/NJ. In the present study, we generated 16 GM mice using a CRISPR/Cas system to target individual and multiple loci simultaneously or consecutively. We also compared homology-directed repair efficiency using different methods for LoxP insertion for conditional knockout mouse production. We found that a two-step serial LoxP insertion, in which each LoxP sequence was inserted individually in different i-GONAD procedures, was a low-risk high-efficiency method for generating floxed mice.

Are breeding activities risky for northern bobwhites? An assessment of survival costs of reproduction

Behaviors associated with breeding can increase mortality risk. This increased risk can be thought of as a cost of reproduction. Increased movements prior to breeding are common as individuals search for food and breeding sites. These increased movements are thought to entail greater predation risks as individuals travel through unfamiliar areas but few studies have looked at how these prebreeding movements affect survival, especially at a fine temporal resolution. Costs of reproduction may also occur during reproduction. For birds, incubation and brood‐rearing can increase predation risk because individuals spend most of their time at nest sites or with broods, which may make them more easily detected and captured by predators. Using time‐ and individual‐specific predictors of survival, I examined the relationship between survival, movements, habitat use and breeding status of northern bobwhites Colinus virginianus in Colorado, USA. I found that prebreeding ranges were larger for breeders (29 ha) than non‐breeders (18.7 ha) but daily movement distance was not different (163 m). Range size did not affect survival; however, longer recent daily movement distances (within 10 days) resulted in higher survival. Breeding status also affected survival; laying individuals experienced the highest daily survival rates followed by incubating, non‐breeding and brood‐rearing individuals. Overall, there appears to be a survival cost of reproduction for individuals during brood‐rearing, but I found no evidence that increased movements results in decreased survival.

Alterations in gonadotropin, prolactin, androgen and estrogen receptor and steroidogenesis-associated gene expression in gander testes in relation to the annual period

Physiological mechanisms of seasonal changes in testicular function in birds are not fully elucidated. The balance between androgens and estrogens and testis sensitivity for gonadotropin and gonadal steroids are still unclear. The aim of the study was to examine: (1) the changes in circulating and intra-testicular steroid hormone levels and their relationship; (2) the mRNA expression of testicular gonadotropin, prolactin (PRL), progesterone (P4), androgen, and estrogen receptors, and (3) key steroidogenesis processes-related genes with immunofluorescent localization of aromatase in gander testes during the annual period. Testes from ganders (n = 25) in the first reproduction season were obtained at five breeding stages, i.e., prebreeding (PrB), peak of reproduction (PR), postbreeding (PoB), nonbreeding (NB), and onset of reproduction (OR). Males were kept under breeding conditions. It was found that plasma P4 levels decreased at the PoB and NB stages, whereas intra-testicular P4 was the highest in the NB stage. Intra-testicular estradiol (E2) levels were higher at the PoB and NB stages than the other stages, whereas testosterone (T) levels showed a nearly opposite pattern. The plasma estradiol–to–testosterone ratios were higher at the PrB, PoB and NB stages compared to other stages. The transcript abundances for luteinizing hormone receptor (LHR), PRL receptor (PRLR), estrogen receptor alpha (ERα), and estrogen receptor beta (ERβ) also change in testicular tissue during the annual period. Moreover, StAR mRNA expression was upregulated at the PoB and NB stages, and CYP11A1 transcript level was the highest at the PoB stage. Stage-dependent changes in the CYP19A1 mRNA and aromatase protein levels with higher abundances of transcript at PoB and NB stages and protein at the NB stage were observed. Localization and immunofluorescent signal intensity for aromatase also differed in relation to the examined stages. It may be suggested that differential E2 levels, as well as aromatase expression and localization across annual stages are responsible for the seasonal activation/inactivation stages of testis spermatogenesis in domestic ganders. These data strongly suggest a role of aromatase in the control of gander steroidogenesis as changes in this enzyme level are associated with alternation in gonadal steroid hormones. In addition, joint action with others hormones, like PRL and LH, seems to be important in the final effect of seasonal reproduction potential.

Housing conditions and biological indices for juvenile coho salmon of 2017–2021 generations grown at the Yansky salmon fish factory in the Magadan region

Biological and morphophysiological parameters of juvenile coho salmon of artificial origin grown at the Yansky salmon hatchery in the Magadan region are analyzed. The breeding conditions and the larvae and juveniles development in 2017–2021 are compared.

Production of recombinant proteins including the B-cell epitopes of autolysin A of Staphylococcus aureus isolated from clinical sheep mastitis and their potential for vaccine development.

Staphylococcus aureus is the most common clinical mastitis-associated pathogen in sheep which contributes to reduced welfare of affected animals and, therefore, compromises the quality and quantity of milk production. To prevent mastitis and its spread, it is essential to guarantee adequate breeding conditions and animal health, through the adoption of good farm management practices and the application of suitable biosecurity measures. Vaccination can play a strategic role in prevention, control, and eradication of diseases. The identification of secreted and cellular antigens of the predominant sheep-CC130/ST700/t1773 lineage would assist in the design of effective vaccine against mammary infections caused by S. aureus. In the current study, we carried out a 3D structural prediction analysis with the identification of the best B cell epitopes of the whole and secreted portion of S. aureus AtlA. Fragments of atlA, containing the main predicted epitopes, were amplified, cloned, and expressed in Escherichia coli for recombinant protein production. Two selected clones produced recombinant proteins (rAtl4 and rAtl8) showing strong reactivity with a hyperimmune serum against the native AtlA and with blood sera collected from sheep with clinical S. aureus mastitis. These may represent potential candidate protein-based vaccines able to elicit a protective immune response to be evaluated by vaccination and subsequent challenge of the vaccinated sheep.

Влияние абиотических факторов на показатели продуктивности А. var. Principalis в аквакультуре

The work is devoted to the study of the influence of abiotic factors, primarily the salinity level on the productivity of artemia in aquaculture in situ. The problem is relevant, since in the last decade there has been an increase in global aquaculture production by 35%, which has led to an increase in the need for artemia cysts and the nauplia obtained from them. Due to the shortage on the world market of artemia cysts extracted in natural ecosystems and their high cost, there is a need to improve the methods of cultivating artemia in a closed cycle in an artificial ecosystem – in aquaculture. To develop effective methods of cultivating artemia in situ, it is important to know the production and morphological indicators of different types of artemia and its races in an artificially created environment. It is known that there is a wide ecological valence of the reproductive function of artemia in relation to varying environmental factors. One of the most important factors determining the reproductive potential of artemia is the salinity of the environment. The level of salinity of water has a great influence on the productivity of artemia crustaceans, both in the natural environment and in aquaculture. The aim of our study was to assess the reproductive potential of artemia and optimize the salinity of the environment to increase the reproductive potential in conditions of artificial breeding in situ. The results of the study showed that with an increase in the concentration of salt in the solution for the cultivation of the available artemia race – A. var. Principalis, – the proportion of synchronously fruiting females increased. When studying the absolute fertility of artemia, it was shown that an increase in the salinity level of the habitat at the reproductive age of females makes it possible to increase their absolute fertility when growing in a closed cycle in aquaculture.

Economic efficiency of castration of boars using different methods on the background of immunocorrection under the conditions of industrial technology

The article presents the results of determining the economic efficiency of the use of two immunocorrectors — thymogen and mikovit (ribav) during castration of boars in industrial technology.The studies were performed on 49 boars (aged 5 months), divided into seven groups — two control and five experimental ones (n=7 in each).All animals were castrated: in the 1st control, 1st, 2nd, 3rd and 4th experimental groups — using open method; in the 2nd control and the 5th experimental groups — using closed method. Preoperative support was carried out according to the methodology used to the farm.The boars of the experimental groups were additionally treated with immunomodulators: in the first one — with thymogen (five-day course before surgery), in the second one — with mycovit (ribav), according to the scheme of the first group with local application after surgery, in the third — according to the scheme of the first group, but after the surgery; in the 4th and 5th — only with the working solution of mikovit (ribav) according to the method of the 2nd experimental group.The economic effect of the developed schemes was defined as the difference between the damage prevented as a result of veterinary measures and veterinary costs, taking into account the additional cost obtained by increasing the quantity of manufactured products and improving their quality. As an additional method, the total index of the effectiveness of veterinary measures was used, which was calculated by multiplying the economic damage by veterinary costs (per animal in each group) and then dividing the resulting number by their minimum multiplication.It was shown that the inclusion of thymogen at a dose of 100 μg/cm3 into the basic regimen of intramuscular injections with a five-day course after surgery using an open castration method or irrigation of the wound surface according to the above scheme with the solution of mycovit (ribav) can significantly increase the economic effect of veterinary measures. In the conditions of industrial pig breeding (taking into account the higher manufacturability of the application), preference should be given to thymogen.

Experience of hybridization and prospects for its application in sheep breeding

A unique project on the hybridization of domestic sheep with wild bighorn sheep of the Yakut subspecies (Ovis nivicola lydekkeri) was implemented under extreme conditions in Yakutia. Hybridization was performed to obtain new forms that combine productive indicators with specific adaptation qualities to harsh breeding conditions. Viable hybrids of both sexes were obtained via laparotomy during the artificial insemination of domestic sheep with frozenthawed epididymal male bighorn sheep. We compared the hybrids with domestic lambs. At birth, the hybrids had a live weight of 2.65±0.19 kg, which is 29 % less than that of domestic lambs. A difference in live weight was noted before reaching the age of 20–24 months; however, by 36 months, hybrid males outnumbered domestic rams of the same age. We found that in the early postnatal period, hybrids were satisfied with their mothers’ milk faster and more often, and their daytime sleep was short and shallow. The hybrids also showed a high degree of curiosity, jumping ability, caution, and clear imitation of the mothers’ behavior. In terms of growth and development, the hybrids were tall and narrow-bodied because of their high mobile activity, as well as differences in nutrition. The hybrid offspring differed in chromosome set from the parental forms, having a diploid set equal to 2n = 53, whereas the maternal form of the sheep had 2n = 54, and the paternal form had 2n = 52. The resulting hybrids are fertile, and differ from their peers in the dynamics of development, nutrition, and ethology. They have phenotypic features similar to those of the paternal form, and a new improved form of the genotype is the basis for selection in sheep breeding.

Advances in the Application of Phytogenic Extracts as Antioxidants and Their Potential Mechanisms in Ruminants.

Under current breeding conditions, multiple stressors are important challenges facing animal husbandry in achieving animal wellbeing. For many years, the use of antibiotics has been a social concern in the livestock industry. With the implementation of the non-antibiotics policy, there is an urgent need to find relevant technologies and products to replace antibiotics and to solve the problem of disease prevention during animal growth. Phytogenic extracts have the unique advantages of being natural and extensive sources, having a low residue, and being pollution-free and renewable. They can relieve the various stresses, including oxidative stress, on animals and even control their inflammation by regulating the signaling pathways of proinflammatory cytokines, improving animal immunity, and improving the structure of microorganisms in the gastrointestinal tract, thereby becoming the priority choice for improving animal health. In this study, we reviewed the types of antioxidants commonly used in the livestock industry and their applicable effects on ruminants, as well as the recent research progress on their potential mechanisms of action. This review may provide a reference for further research and for the application of other phytogenic extracts and the elucidation of their precise mechanisms of action.

Transcriptome and GWAS Analyses Reveal Candidate Gene for Root Traits of Alfalfa during Germination under Salt Stress

Alfalfa growth and production in China are negatively impacted by high salt concentrations in soils, especially in regions with limited water supplies. Few reliable genetic markers are currently available for salt tolerance selection. As a result, molecular breeding strategies targeting alfalfa are hindered. Therefore, with the continuous increase in soil salinity in agricultural lands, it is indispensable that a salt-tolerant variety of alfalfa is produced. We collected 220 alfalfa varieties around the world for resequencing and performed genome-wide association studies (GWASs). Alfalfa seeds were germinated in saline water with different concentrations of NaCl, and the phenotypic differences in several key root traits were recorded. In the phenotypic analysis, the breeding status and geographical origin strongly affected the salt tolerance of alfalfa. Forty-nine markers were significantly associated with salt tolerance, and 103 candidate genes were identified based on linkage disequilibrium. A total of 2712 differentially expressed genes were upregulated and 3570 were downregulated based on transcriptomic analyses. Some candidate genes that affected root development in the seed germination stage were identified through the combination of GWASs and transcriptome analyses. These genes could be used for molecular breeding strategies to increase alfalfa's salt tolerance and for further research on salt tolerance in general.

Future of birds nesting on river islands in the conditions of hydrological variability caused by climate change

The mew gull (Larus canus), little tern (Sternula albifrons) and black-headed gull (Chroicocephalus ridibundus) are threatened in Poland by the loss of breeding habitats due to changes in the hydrological regime of rivers and the frequency and length of inundation. Analysis of daily flows generated from the SWAT model allowed us to obtain the values of hydrological characteristics expressed as Indicators of Hydrological Alteration (IHA) and find the relationship with collected data on nesting success on islands and sandbanks in the Middle Vistula from 2004 until 2018. For each bird species, a set of adjusted IHA was calculated for future scenarios (2021-2050 and 2071-2100). The projections were prepared on the basis of EURO-CORDEX and contain two scenarios of changes in greenhouse gas concentrations: RCP4.5 and RCP8.5. Catastrophic breeding seasons quantification was carried out to assess the number of years that will have unsuitable hydrological breeding conditions in the projected climate change. The mew gull noted the lowest nesting success (during 2004-2018) but it seems that hydrology is not the principal factor causing it. This species will experience an increase in high flows due to climate change in the far future scenarios. The black-headed gull is projected not to be affected by an increase in the percentage of catastrophic breeding seasons due to climate change. The little tern seems to be the most affected by projected climate change due to an increase in high flows and, in consequence, an increasing percentage of catastrophic breeding seasons. The results confirmed the importance of hydrologic change for avian nesting success.

Associations Between Dog Breed and Clinical Features of Mammary Epithelial Neoplasia in Bitches: an Epidemiological Study of Submissions to a Single Diagnostic Pathology Centre Between 2008–2021

Mammary cancer is one of the most common neoplasms of dogs, primarily bitches. While studies have been carried out identifying differing risk of mammary neoplasia in different dog breeds, few studies have reported associations between dog breeds and clinical features such as number of neoplastic lesions found in an individual case or the likelihood of lesions being benign or malignant. Such epidemiological studies are essential as a foundation for exploring potential genetic drivers of mammary tumour behaviour. Here, we have examined associations between breed, age and neuter status and the odds of a diagnosis of a mammary epithelial-origin neoplastic lesion (as opposed to any other histopathological diagnosis from a biopsied lesion) as well as the odds of a bitch presenting with either a single mammary lesion or multiple lesions, and the odds that those lesions are benign or malignant. The study population consisted of 129,258 samples from bitches, including 13,401 mammary epithelial neoplasms, submitted for histological assessment to a single histopathology laboratory between 2008 and 2021.In multivariable analysis, breed, age and neuter status were all significantly associated with the odds of a diagnosis of a mammary epithelial-origin neoplastic lesion. Smaller breeds were more likely to receive such a diagnosis. In cases diagnosed with a mammary epithelial neoplasm, these three factors were also significantly associated with the odds of diagnosis with a malignant lesion and of diagnosis with multiple lesions. Notably, while neutered animals were less likely to have a mammary epithelial neoplasm diagnosed, and were less likely to have multiple neoplasms, they were more likely to have malignant disease. Exploration of the patterns of risk of developing malignant disease, or multiple lesions, across individual breeds showed no breed with increased odds of both outcomes. Breeds with altered odds compared to the Crossbreed baseline were either at increased risk of malignant disease and decreased risk of multiple lesions, or vice versa, or they were at significantly altered odds of one outcome with no change in the other outcome. Our analysis supports the hypothesis that age, neuter status and intrinsic biological and genetic factors all combine to influence the biological heterogeneity of canine mammary neoplasia.