Animal Science Papers and Reports Feed

Pedigree analysis: estimation of genetic parameters and the effect of inbreeding on dairy traits in Simmental cattle

Sat, 28 Mar 2026 00:00:00 GMT

The objectives of this study were (1) to evaluate the level of inbreeding by estimating inbreeding coefficients and (2) to estimate the effect of inbreeding on lactational milk traits in Polish Simmental cows. Two reference populations were defined for pedigree analysis: animals born between 1984 and 2009 (dataset A, n=20,827) and animals born between 2010 and 2020 (dataset B, n=19,554). Mean inbreeding coefficients for the analysed cows were generally low in both reference populations, however, approximately 72% of the inbred cows were born in the second studied decade. Notably, an increased number of ancestors did not result in an increase in genetic diversity. 7 founders exhibited the highest gene contribution. The principal ancestors with the highest gene contribution were 11 sires in dataset A and 15 animals in dataset B. The coefficients of regression on inbreeding were low and negative for milk yield and fat or protein content for all three lactations, whereas positive effects were observed for fat or protein percentage. Overall, the genetic variability of Polish Simmental cows is at a satisfactory level, nevertheless in young cows an increase in the number of inbred individuals is observed. Analysis of ancestral gene contributions indicates significant changes in the composition of ancestors in this younger population.

Three-dimensional culture of heart tissue constructs from heart progenitor cells on a polycaprolactone scaffold - optimization

Sat, 28 Mar 2026 00:00:00 GMT

Myocardial damage resulting from ischemia leads to the irreversible loss of cardiac function. Consequently, there is a critical need to develop effective therapies capable of regenerating damaged heart muscle. Tissue engineering (TE) enables the creation of functional tissues in vitro using cells, biologically active molecules, and scaffolding methods. To advance research on heart tissue culture on polycaprolactone (PCL) scaffolds, it is important to optimize culture methods to ensure adequate nutrient supply. In this study, different sera and various concentrations of heart tissue extracts were evaluated for their ability to support cardiac pseudo-tissue formation on PCL scaffolds using progenitor cells at different stages of differentiation. The results confirm the biocompatibility of PCL with cardiac progenitor cells. Cardiac progenitors, collected on the 8th embryonic day (8 ED), demonstrated the greatest potential for forming heart pseudo-tissue constructs when cultured with horse serum (HS) and an extract from homogenized hearts of 14-day-old chicken embryos as an additive to the culture medium. Cardiac progenitor cells collected on 12 ED exhibited the highest potential for creating pseudo-heart tissue constructs in the presence of HS, even without the addition of homogenized heart extract. Moreover, a high concentration of the extract reduced their ability to form structured tissue constructs. Overall, HS promoted more intensive cell proliferation in both 2D, and 3D cultures compared to foetal bovine serum (FBS). The absence of a vascular-like system limits the development of large tissue constructs, leading to nutritional deficiency and subsequent tissue degradation.

Quality parameters of table eggs depending on genotype and age in selected laying hens

Sat, 28 Mar 2026 00:00:00 GMT

The aim of this study was to perform a comparative analysis of table egg quality in relation to the genotype and age of laying hens. A total of 180 eggs were analysed, comprising 30 eggs from Lohmann Brown hens and 30 eggs from Lohmann LSL hens at 25, 50, and 72 weeks of age. Morphometric traits (egg weight, length, width, and shape index), shell characteristics (eggshell surface area, shell thickness, and shell strength), and quantitative traits of egg components (percentage of shell, albumen, and yolk; thick albumen height; Haugh units; and yolk colour parameters L*, a*,b* and Roche score) were evaluated. In addition, feed conversion ratio, egg production rate, and total egg number per hen were recorded throughout the laying period. The results showed a significant effect of hen genotype on egg weight (Lohmann Brown: 64.70 g vs. Lohmann LSL: 59.97 g), egg length and width, egg shape index, eggshell surface area and strength, albumen proportion (65.09 vs. 63.23%), yolk proportion (24.90 vs. 26.72%), thick albumen height, Roche score, Haugh units, and yolk b* colour. Hen age significantly affected egg weight (25 weeks: 56.77 g vs. 72 weeks: 66.20 g), egg width and length, the proportion of shell, albumen (25 weeks: 65.71% vs. 50 weeks: 62.71%), and yolk, eggshell surface area (25 weeks: 70.08 cm² vs. 72 weeks: 77.58 cm²), as well as yolk colour parameters L* and a*. Significant genotype × age interactions were observed for egg weight and width, egg shape index, and also eggshell surface area and strength, Haugh units, and yolk colour parameters a* and b*.

Energy and nutrient utilisation of laying hens fed fibre rich diet containing graded levels of supplementary fungal xylanase

Sat, 28 Mar 2026 00:00:00 GMT

The effect of graded levels of exogenous xylanase (XYL) at 0, 1500, 2000 or 2500 xylanase units (XU/kg) in laying hen diet containing 300 g/kg wheat distillers dried grains with solubles (DDGS) was examined. A total of 72, twenty-two-week-old, Hy-Line Brown laying hens were allocated to 24 cages, three birds in a cage. Each diet was fed for nine days to six cages following randomisation. Supplementing diets with 2500 XU, the highest XYL level, increased (p<0.05) dietary apparent metabolisable energy (AME) and nitrogen corrected AME (AMEn) in a linear pattern (L<0.05), and nitrogen retention coefficient (p<0.05) following quadratic response (Q<0.05). For every 100 XU, dietary AME and AMEn increased by 0.013 MJ and 0.012 MJ, respectively. There were no differences observed in bird growth or egg production variables. Further research is warranted to study the impact of greater XYL activities in laying hen diets formulated to contain greater DDGS inclusion rates.

Effects of standardized allicin on production performance, welfare and meat quality of broiler chickens

Sat, 28 Mar 2026 00:00:00 GMT

The aim of the study was to evaluate the standardized allicin effect on the health, productivity and meat quality of broilers. The antimicrobial properties of the preparation and its impact on the intestinal microbiota were evaluated. It was also attempted to determine the lowest effective dose of preparation. 960 Ross 308 chickens were divided into 4 groups (8 replications each). Birds were maintained in a litter pen with a stocking density of 33 kg/m2 and constant access to feed and water. The groups were differentiated by the preparation used: group 1 (control), without supplementation, then standardized allicin doses of 150, 200 and 250 μg/kg body weight were applied in group 2, 3 and 4, respectively at 3-day intervals. The birds’ productivity was recorded over 42 days, then 16 birds/ group were slaughtered and dissected. Samples of meat were collected. There were no differences in the final body weight of the birds, but significantly the lowest feed conversion ratio and highest livability rate in group 4 were found. The allicin-supplemented groups showed a lower incidence of foot pad dermatitis, as well as a quantitative reduction in the aerobic bacteria in the intestinal contents. No effect on the quality of the meat obtained was noticed.

Transdermal drug delivery: a bibliometric analysis of global trends and emerging device-assisted techniques

Sat, 28 Mar 2026 00:00:00 GMT

Transdermal drug delivery has evolved from conventional topical formulations to advanced approaches designed to overcome the barrier function of the stratum corneum. This study provides a comprehensive bibliometric analysis of transdermal drug delivery research, with particular attention to emerging device-assisted techniques, including laser-assisted delivery and pneumatic needle-free injection systems. Bibliometric data were retrieved from the Web of Science using a systematic search strategy, yielding 15,865 publications between 1977 and 2025. The dataset was analyzed using VOSviewer to visualize recurring research themes, collaboration networks, and citation impact. The results demonstrate a marked growth in scientific output since the early 2000s, with original research articles representing the predominant publication type. The United States and China were the leading contributors to the field, while Ryan F. Donnelly (Queen’s University Belfast) was identified as the most productive author. Among the most frequently studied transdermal drug delivery approaches were microneedles, iontophoresis, and lipid-based carriers, reflecting sustained interest in minimally invasive and formulation-driven strategies. Although laser-assisted techniques and needle-free injection were less represented in terms of publication volume, needle-free injection demonstrated a high citation impact. Laser-assisted drug delivery was less frequently represented in the dataset, likely reflecting its later emergence and methodological heterogeneity rather than a lack of scientific interest. Overall, transdermal drug delivery research is rapidly expanding across pharmacology, biomaterials science, and biomedical engineering, highlighting the interdisciplinary nature of innovation in this field.

Fattening performance, carcass traits, and meat quality of pigs from DanBred sows and Topigs Norsvin boars

Sat, 28 Mar 2026 00:00:00 GMT

The study evaluated fatteners produced by crossing DanBred Yorkshire-Landrace (YL) sows with purebred Landrace, Pietrain, and Duroc boars from Topigs Norsvin. Approximately 200 pigs were assessed per crossbred group. From each group, 60 carcasses were analysed for lean meat content using the AutoFom device, and longissimus lumborum (LL) muscles from 30 carcasses were collected for meat quality evaluation. Pigs sired by Duroc boars exhibited significantly higher average daily gain (ADG) than Pietrain-sired pigs, while feed intake and feed conversion efficiency did not differ among groups. Carcasses from Landrace- and Pietrain-sired pigs contained more lean meat than those from Duroc-sired pigs. Across individual cuts (ham, loin, shoulder, and belly), Pietrain-sired pigs showed the highest lean meat content, followed by Landrace, with the lowest values observed in the Duroc group. Meat quality traits were most favourable in Duroc-sired pigs, as indicated by higher pH values and lower drip and thawing losses in both fresh and frozen meat. Their LL muscles also contained higher dry matter and intramuscular fat (IMF) levels compared with those of Landraceand Pietrain-sired pigs. These attributes translated into superior sensory quality, reflected in higher scores for aroma, tenderness, juiciness, and flavour, as well as lower shear force values.

From ancient roots to modern routes: a systematic review of ginger’s anti-motion sickness efficacy in randomized clinical trials and animal studies

Sat, 28 Mar 2026 00:00:00 GMT

Motion sickness is a neurosensory dysfunction characterised by nausea, vomiting, dizziness, and general discomfort. Although there are conventional medications for this condition, interest in herbal alternatives like ginger (Zingiber officinale) is growing due to its broad biological activities and safety profile. Usually, females are more prone to motion sickness. Ginger contains phenolic chemicals that have anti-inflammatory, anti-microbial, anti-cancer, neuroprotective, anti-diabetic, cardiovascular, anti-obesity, anti-emetic, and protective actions against respiratory illnesses. These biological activities have led to its usage in traditional medicine to treat symptoms such as motion sickness, morning sickness, nausea, vomiting, indigestion, nausea and vomiting induced by chemotherapy and pregnancy. This systematic review of randomised controlled trials (RCTs) and animal studies was conducted using PubMed, Web of Science, and DOAJ in accordance with PRISMA guidelines. Four RCTs (involving 469 participants) and only one animal study met the inclusion criteria, and ginger was administered in doses ranging from 500 to 2,000 mg. One RCT study, which used low-dose ginger, revealed ginger to be less beneficial than a multivitamin-based treatment, whereas three trials reported a significant decrease in nausea and vomiting compared to a placebo. There were no significant side effects noted. In conclusion, these investigations have shown that ginger is effective and tolerable in treating motion sickness. Although there is a lot of evidence supporting ginger’s safety, effectiveness, and reduction of motion sickness, additional research is needed to ensure its efficacy.

Somatic cells – causes and consequences of their varying presence in cow milk

Mon, 12 Jan 2026 00:00:00 GMT

This study analyses key aspects of somatic cells in cow milk. It outlines their types, physiological levels, and diagnostic value for udder health, particularly in detecting subclinical mastitis. Methods for determining somatic cell counts are presented, with bacterial infections identified as the main cause of elevated levels. The role of lactose concentration as a practical indicator is highlighted, alongside environmental and genetic factors influencing somatic cell variation in breeding practice. The consequences of high counts – such as reduced milk yield, lower processing quality, and diminished reproductive performance – are summarized. Finally, the study discusses hygiene prophylaxis measures and the role of somatic cell monitoring in dairy cattle improvement programs worldwide.

Evaluation of the fatty acid and carotenoid contents of the yolk and preservation of nutrients in eggs of Japanese quails fed different lipid sources

Mon, 12 Jan 2026 00:00:00 GMT

This study aimed to evaluate yolk lipid content, fatty acids, carotenoids, and the preservation of egg quality in quails fed diets containing different lipid sources. The experiment followed a completely randomized design with five treatments (soybean oil, corn oil, canola oil, sunflower oil, and poultry fat), 10 replicates, and seven birds per experimental unit, totaling 350 quails. Ether extract, carotenoid levels, fatty acid profile, and egg quality after 7 and 14 days of storage were evaluated in relation to lipid inclusions. Data were subjected to analysis of variance, and polynomial regressions were applied to estimate the effects of storage time. The effects of lipid sources were evaluated using Tukey’s test at the 5% significance level. Lipid source had no effect on yolk ether extract content; however, quail fed soybean oil produced eggs with lower carotenoid levels. A significant effect (P≤0.05) of lipid source and of the interaction between lipid source and storage time was observed for egg quality variables, except yolk diameter. Different lipid sources did not influence the preservation of egg quality during storage, but they did affect carotenoid and fatty acid deposition in the yolk. The inclusion of sunflower oil improved the deposition of linoleic acid and β-carotene in egg yolks.

Regression of trophectodermal protrusions in the mouse blastocyst correlates with primitive endoderm formation

Mon, 12 Jan 2026 00:00:00 GMT

This study examined trophectoderm (TE) protrusions covering the inner cell mass (ICM) during blastocyst development. Using fluorescein-labelled latex beads in E3.5 and E4.5 mouse embryos, we assessed the presence of TE protrusions (TP) and their relationship to primitive endoderm (PrE) formation. Beads were endocytosed by outer embryonic cells, enabling visualization of protrusions by confocal microscopy. We observed that TE protrusion coverage of the ICM decreased as blastocyst cell numbers increased, regressing entirely by E4.5. At this stage, no protrusions remained and the ICM exhibited a distinct PrE layer following cell sorting.

Innovative use of Lamiaceae extracts in animal feeding-stuffs and nutritional supplementations: a patent-based analysis

Mon, 12 Jan 2026 00:00:00 GMT

The use of medicinal and aromatic plants (MAPs), particularly those from the Lamiaceae family, has gained remarkable attention in animal nutrition due to their bioactive compounds such as phenolics, terpenes, and flavonoids. These compounds offer multiple benefits, including antimicrobial, antioxidant, and growth-promoting properties, making them ideal candidates for incorporation into feeding products and nutritional supplements specially adapted for animals. This study presents a comprehensive patent analysis to investigate the innovation landscape surrounding feeding-stuffs formulated with Lamiaceae extracts. Patent data was collected from specialized databases (Patentscope, The Lens, and Espacenet) and analyzed based on key International Patent Classification (IPC) codes: A23K (feeding-stuffs adapted for animals) and A61K36/53 (Lamiaceae family). The analysis covered 485 patent documents published between 1977 and 2024, including patent applications, granted patents, and other document types. Results reveal a steady increase in patenting activity, with significant peaks observed in 2008, 2018, and 2021, reflecting the growing interest in natural feed formulations. China (83 documents) emerged as the leading jurisdiction, followed by the United States (74 documents) and Japan (69 documents). Major applicants, including Nestlé SA and Ralco Nutrition Inc., demonstrated a strong focus on leveraging Lamiaceae extracts in animal nutrition. The technological fields identified through IPC classifications emphasized the role of Lamiaceae in advancing sustainable animal nutrition. This study highlights the innovation potential of Lamiaceae-based feeding-stuffs, underlining their importance in enhancing livestock health and productivity while contributing to eco-friendly agricultural practices. Future research should explore synergistic applications and field validations to optimize their usage in commercial animal nutrition.

Ginger supplementation supports liver health during aging through regulation of lysosomal function and molecular markers

Mon, 12 Jan 2026 00:00:00 GMT

Aging is marked by hepatic structural deterioration, inflammation, and impaired autophagy. This study evaluated the effects of dietary ginger (Zingiber officinale) on liver aging in Swiss Webster mice across three age groups (3, 6, and 12 months) supplemented with 0.6% or 1.8% ginger powder for three months. Liver samples were assessed for lysosomal enzyme activity, expression of PI3K and TNF-α, histology, and ultrastructure of hepatocytes. Aging induced hepatocellular hypertrophy, mitochondrial damage, and increased lysosomal enzyme activity, particularly arginyl aminopeptidase and acid phosphatase, and β-galactosidase - a widely recognized marker of aging, particularly cellular senescence. Ginger supplementation preserved liver morphology in young and middle-aged mice, while high doses showed mild subcellular stress in older mice. Ginger also suppressed age-related PI3K upregulation and influenced TNF-α expression, indicating potential anti-inflammatory effects. These findings suggest that ginger modulates hepatic aging through lysosomal, inflammatory, and metabolic pathways in an age- and dose-dependent manner. Moderate intake appears most beneficial, supporting its potential as a nutraceutical for liver health during aging.

Therapeutic potential of chlorogenic acid in age-associated metabolic and neurodegenerative disorders

Mon, 12 Jan 2026 00:00:00 GMT

Chlorogenic acid (CGA), a polyphenolic compound abundant in coffee and various plants, exhibits broad therapeutic potential in age-related metabolic and neurodegenerative disorders. CGA exerts potent antioxidant, anti-inflammatory, and metabolic regulatory effects by modulating key signaling pathways such as AMPK, SIRT1, mTOR, FOXO, and Nrf2. Preclinical studies demonstrate its ability to mitigate oxidative stress, regulate autophagy, improve lipid and glucose metabolism, and protect against neurodegeneration. Moreover, CGA enhances mitochondrial function and preserves cellular homeostasis. However, emerging evidence suggests that under conditions of low folate or B-vitamin availability, CGA may increase plasma homocysteine levels, raising concerns about its effects on methylation and vascular health. This review provides a comprehensive analysis of CGA’s molecular targets and mechanisms of action, with particular emphasis on its implications in redox regulation, autophagy, metabolic homeostasis, and neurodegeneration. Collectively, current evidence positions CGA as a promising nutraceutical candidate for integrative strategies aimed at preventing or mitigating chronic degenerative diseases and promoting healthy aging.

Indications of associations between polymorphism of the selected genes located on the porcine chromosome 4 and carcass quality traits

Mon, 12 Jan 2026 00:00:00 GMT

DGAT1, AGL and protoncogen c-myc genes have been mapped on chromosome 4 and considered as candidate genes for carcass quality traits. The aim of the study was to characterize the polymorphism of these genes in four groups of pigs and to evaluated the relationship between the DGAT1, AGL and c-myc genotype and carcass traits. The animals of cross-breed PLW x PL were used only to characterize these polymorphisms. All animals studied appeared to be polymorphic at these loci. Statistical analysis was carried out for each breed separately using the least square methods of the GLM procedure. The relationship between the polymorphism and several productive traits was identified in each of the study group of pigs. Animals carrying heterozygous genotype at this locus showed most extreme values for some of the traits tested. Our results suggest that these genotypes might be utilized in the selection of valuable pig carcass traits.

Perspective on pig welfare among different professional groups in Poland

Mon, 12 Jan 2026 00:00:00 GMT

This study examined the knowledge of Polish citizens regarding pig welfare, comparing the perspectives of farmers, animal science/veterinary professionals, students, and regular citizens. An online survey, distributed from August 6th to September 1st, 2023, gathered 140 responses. The survey assessed participants’ understanding of pig welfare and their reactions to videos depicting various pig behaviours. Targeted recruitment ensured that farmers, professionals, and students comprised 42% of the respondents (N=59). Kruskal-Wallis tests and Principal Component Analysis revealed that professional groups exhibited the most significant differences in video perception, with students differing most from regular citizens. All groups accurately identified pig behaviours, suggesting a tendency towards increased animal welfare awareness, even among those with limited farm animal contact. Limitations include the online survey format and targeted recruitment of specific professional groups.

Genetic parameters of conformation traits in Polish Simmental cattle

Tue, 07 Oct 2025 00:00:00 GMT

The aim of the study was to estimate genetic parameters of 6 descriptive and 21 linear conformation traits in Simmentals. The data were obtained from FedInfo, the Polish national recording system, and were provided by the Polish Federation of Cattle Breeders and Dairy Farmers. A multi-trait animal model and a Bayesian method via Gibbs sampling (BLUPf90 package) were used to estimate the genetic parameters of 6 descriptive and 21 linear conformation traits. The analysis included 1.397 recorded Simmental cows and one generation of ancestors, totaling 2.330 individuals. The cows, born between 2007 and 2017, were daughters of 115 sires. The heritability of descriptive traits was low to high and ranged from 0.09 for feet-and-legs to 0.55 for muscularity. Among the linear traits, the highest heritability was estimated for chest circumference (0.69), front-muscularity (0.61) and rear-muscularity (0.60). Traits related to legs were lowly heritable. Descriptive traits showed moderate to high genetic correlations; all were positive and ranged from 0.23 to 0.86. The lowest genetic correlations were estimated between udder and muscularity (0.23), whereas the highest between overall conformation and both udder (0.85) and muscularity (0.86). Among the linear traits the highest genetic correlations occurred between chest circumference and chest width (0.84), front-muscularity (0.88) and rear-muscularity (0.80), as well as between chest width and both front-muscularity (0.84) and rear-muscularity (0.82). Front-muscularity and rear-muscularity were also highly genetically correlated (0.89).

Assessment of spatiotemporal development of cell lineages in the mouse blastocyst using bespoke cell neighbourhood analysis approaches

Tue, 07 Oct 2025 00:00:00 GMT

This work demonstrates the efficiency of the software IVEN (Internal Versus External Neighbourhood) in describing the dynamic changes in neighbourhoods of all cell lineages in the mammalian blastocyst. In the mouse model, the primitive endoderm (PrE)/epiblast (Epi) dichotomy is established during blastocyst formation, which results in a seemingly random distribution of cells from both lineages within the ICM (‘salt and pepper’ model). Nevertheless, differences in cell potency, plasticity and distribution suggest that specific cell traits, such as environment, might be defining the ultimate fate acquisition. We have tested the new functionalities in the latest IVEN version and its efficiency to explore the changes in cell distribution within cell lineages and sub-populations. For this purpose, we have developed pipelines that combine functionalities from the imaging software (IMARIS) with IVEN internal algorithms to provide an insight into the dynamic cell neighbourhood within the early blastocyst. IVEN returns detailed reconstructions and numerical arrays that can be interpreted to describe the evolution of cell neighbourhoods within and between lineages. Thus, we have been able to identify specific subsets of cells within the TE and the ICM lineages depending on their relative position to the blastocyst cavity and revealed distinct neighbourhood features. IVEN analyses were essential to provide quantitative understanding of the intrinsic dynamics of the mouse blastocyst. Our approach demonstrates the accuracy of IVEN as a descriptive analytical tool and offers the possibility of applying it on to other systems to uncover differences between species.

The influence of age and sex on carcass composition, digestive system morphometry and leg bone dimensions in Japanese quail

Tue, 07 Oct 2025 00:00:00 GMT

Japanese quails are birds that are mainly reared for meat and egg production. Early sexual maturity and a high reproduction rate have contributed to the development of this poultry sector. This study investigated the effects of age, sex, and their interactions on the carcass composition, digestive system morphometry, and leg bone dimensions. The research was conducted on 40 Japanese quails: 20 birds at 6 weeks of age (10 males and 10 females) and 20 birds at 52 weeks of age, at the end of the egg production period (10 males and 10 females). Post-slaughter, body weight and the relative proportions of carcass components were recorded. Additionally, the lengths and diameters of intestinal segments, their proportions relative to total intestinal length, and morphometric measurements of the femur and tibia were assessed. The results showed that age significantly affected body weight, with older quails weighing more (174.30±23.59 g) than younger ones (166.94±10.25 g; p<0.05). Also, age significantly influenced the percentage of leg muscles, as well as the relative weights of the gizzard and spleen, and several morphometric parameters of the tibia and femur. Sex had a significant effect, too. Females exhibited higher body weights than males (177.49±26.95 g vs. 163.75±8.41 g) along with changes in selected osteometric dimensions of the tibia and femur. Some traits showed interaction effect. Overall, both age and sex significantly influence carcass composition and selected morphometric characteristics of the femur and tibia, while body weight increases with age and the relative proportion of leg muscles decreases.

Seasonal variation of sex hormones and semen quality in Simental bulls

Tue, 07 Oct 2025 00:00:00 GMT

The purpose of this study was to find out whether the seasonal climate changes have any impact on sex hormones levels and semen characteristics in Simmental bulls kept in the insemination station. The study was conducted for a year. Ejaculates of twelve bulls were collected from each bull three times a month using an artificial vagina. Basic semen characteristics - ejaculate volume, sperm concentration, motility, and percentage of live sperm - were assessed in the collected samples. Blood was drawn monthly from the bulls to measure testosterone and estradiol levels. Significant differences were found in the levels of sex hormones in blood serum and in the bull sperm depending on the season. The highest testosterone levels were observed in summer, while estradiol levels in spring. Semen concentration was best in summer, motility in spring and viability in autumn. There was no clear relationship between hormone levels and semen parameters. The obtained results suggest that season has a large impact on the serum testosterone and estradiol levels and also on bovine sperm parameters.