Volume 19 (2019): Issue 3 (July 2019)

Lameness in dairy cows is a worldwide problem, usually a consequence of hoof diseases. Hoof problems have a negative impact on animal health and welfare as well as the economy of the farm. Prevention and early diagnosis of lameness should prevent the development of the disease and consequent high costs of animal treatment. In this review, the most common causes of both infectious and noninfectious lesions are described. Susceptibility to lesions is primarily influenced by the quality of the horn. The quality of the horn is influenced by internal and external conditions such as hygiene, nutrition, hormonal changes during calving and lactation, the animal’s age or genetic predisposition. The next part of this review summarizes the basic principles and possibilities of using infrared thermography in the early detection of lameness in dairy cows.

A trend of global warming has been observed over the last few years and it has often been discussed whether there is an effect on livestock. Numerous studies have been published about heat stress in cattle and its influence on the physiology and productivity of animals. Preventing the negative effects of heat stress on cattle is essential to ensure animal welfare, health and productivity. Monitoring and analysis of physiological parameters lead to a better understanding of the adaptation processes. This can help to determine the risk of climate change and its effects on performance characteristics, e.g. milk yield and reproduction. This, in turn, makes it possible to develop effective measures to mitigate the impact of heat load on animals. The aim of this article is to provide an overview of the current literature. Studies especially about the physiological and productive changes due to heat stress in cattle have been summarised in this review. The direction of future research into the aspect of heat stress in cattle is also indicated.

The aim of the study was to determine genetic parameters of live performance traits in pigs of three native breeds maintained in Poland. As part of the conservation programmes, the Puławska (Puł), Złotnicka White (ZW) and Złotnicka Spotted (ZS) breeds are monitored for productivity based on performance test results of these breeds. The study included 6042 gilts and 2406 boars of the Puławska breed, 866 Złotnicka White gilts, and 903 Złotnicka Spotted gilts. The genetic parameters were estimated separately for each breed, and also separately for sexes in the case of the Puławska breed. The components (co)variance and genetic parameters were estimated using the REML method for the animal model taking into account different combination of fixed and random effects. Convergence of the iterative process was achieved by the selection of AIREML algorithm. The coefficients of genetic and phenotypic correlations between measurements of slaughter traits and daily gain were low for all breed groups. In turn, the relationships between backfat thickness measurements and carcass meat percentage were estimated as high. Only the correlations of slaughter traits with loin eye height were not uniform for the analysed breed groups. The coefficients of heritability (h²) were high and intermediate for all breeds and sexes. The highest heritability coefficients were obtained for daily gain (0.58 in ZW to 0.80 in Puł gilts), followed by backfat thickness (0.37 in Puł gilts to 0.64 in ZW) and carcass meat percentage (0.40 in ZS to 0.56 in ZW). The lowest coefficients were obtained for loin eye height (0.24 in Puł boars to 0.40 in ZW). The estimated genetic parameters could be used to verify selection indices of the breeds included in the genetic resources conservation programmes.

The goat (Capra hircus) is a perfect animal model for analyzing the transcriptome of milk somatic cells (MSCs), as sufficient numbers of somatic cells in goat milk, i.e., exfoliated epithelial cells, can be obtained using noninvasive methods. RNA integrity and purity are the first and most important parameters qualifying samples for transcriptomic tests and next-generation sequencing, as RNA quality influences experimental results. The aim of this study was to optimize a method for obtaining high-quality RNA from goat MSCs, irrespective of effects like breed, lactation stage, health status (e.g., with or without small ruminant lentivirus [SRLV] infection), or number of somatic cells. Milk samples were obtained from goats of two Polish breeds in various lactation stages and in different parities, and from goats infected and not infected with SRLV. Altogether, 412 MSC samples were examined: 206 using method A with fenozol and 206 using method B with QIAzol. Though the overall purity (measured as absorbance ratios at 260 nm/280 nm and 260 nm/230 nm) of the RNA material was comparable, the average yield of RNA isolated using method A was 11.9 µg, while method B’s average yield was 29.9 µg. Moreover, method B resulted in good quality RNA suitable for transcriptome analysis. Results were confirmed by RT-qPCR, using 18S rRNA and RPLP0 as the reference genes. The application of our modified treatment method was successful in obtaining high-integrity samples for transcriptomic or next-generation sequencing analysis. Using a 400 mL milk sample cooled in ice directly after milking, securing the cooling chain process from milking to MSC isolation, and applying method B to isolate RNA, we obtained good RNA quality irrespective of the goats’ breed, lactation stage, parity, milk yield, SRLV infection, and even milk yield and number of somatic cells in milk.

The aim of the study was to find associations between the process of neoplastic transformation and mtDNA mutations/polymorphisms, i.e. factors with potential prognostic significance, and to determine their impact on the biochemical properties, as well as structural, and functional properties of proteins. Blood and neoplastic tissue samples were collected from a 9-year-old Labrador dog with a diagnosed malignant mammary tumour. Next-generation genome sequencing (NGS) of the entire mitochondrial genome was performed using Illumina technology, and bioinformatics analyses were carried out. This is the first report demonstrating the application of NGS in the analysis of the canine mtDNA genome in neoplastic disease. The proposed strategy is innovative and promising. For the first time in the literature, the sequence of 29 genes was analysed to determine their association with the prevalence of tumour. In total, 32 polymorphic loci and 15 mutations were identified. For the first time, as many as 24 polymorphisms and all the mutations have been described to be associated with the neoplastic process in dogs. Most polymorphisms/mutations were found in the D-loop (31% of the polymorphisms and 93% of the mutations) and the COX1 gene sequence (16% of the polymorphisms). Blood or cancer heteroplasmy was noted in 93% of the mutations. Four of the 18 polymorphisms detected in the protein-coding genes were non-synonymous polymorphisms that have not been described in the literature so far (m.T7593C in COX2, m.G8807A in COX3, m.A9911G in ND4L, and m.T13299A in ND5) but resulted in changes in amino acids in proteins. These mutations and polymorphisms can affect mitochondrial functions and may be a result of cell adaptation to the changes in the environment occurring during carcinogenesis. The replacement of “wild type” mtDNA by a mutated molecule may be an important phenomenon accompanying carcinogenesis.

Single-nucleotide polymorphisms (SNPs) have been used in genomic prediction and shown to increase prediction accuracy and selection responses for economic traits in dairy cattle. The successful report in genomic prediction for improving age at first calving (AFC) and 305-d milk yield (MY) in multibreed dairy population is limited. Therefore, the objective of this research was to compare estimates of variance components, genetic parameters, and prediction accuracies for AFC and MY using a genomic-polygenic model (GPM) and a polygenic model (PM). The AFC and MY records of 9,106 first-lactating multibreed dairy cows, calved between 1991 and 2014, were collected from 1,012 Thai dairy farms. The SNP genotyped individuals were selected from cows that had completed pedigree and phenotypes information. The total genomic DNA samples of 2,661 dairy cattle were genotyped using various GeneSeek Genomic Profiler low-density bead chips (9K, 20K, and 80K). The 2-trait GPM and PM contained herd-year-season and heterosis as fixed effects, and animal additive genetic and residual as random effects. Variance components and genetic parameters were estimated using the procedure of average information-restricted maximum likelihood (AI-REML). Estimates of additive genetic variance components and heritabilities from GPM were higher than PM for AFC and MY. Correlations between AFC and MY were near zero for both models. Mean EBV accuracies were higher for GPM (32.95% for AFC and 38.24% for MY) than for PM (32.65% for AFC, and 32.99% for MY). Mean sire EBV accuracies were higher for GPM (31.35% for AFC and 36.25% for MY) than for PM (28.37% for AFC and 28.80% for MY). Thus, the GPM should be considered the model of choice to increase accuracy of genetic predictions for AFC and MY in the Thai multibreed dairy population.

The aim of the study was to investigate the impact of the implementation of new health traits into the breeding objective and selection criteria for Czech Holstein cows on the genetic selection response in the breeding objective traits. Incidence of overall claw diseases was included into the current breeding objective for cows (11 traits together). Three traits that indicated claw health (incidence of claw diseases overall and infectious and non-infectious claw diseases) and incidence of clinical mastitis were successively added to the current selection criteria in a cow selection index (a maximum of 19 traits). Selection responses in the breeding objective traits were estimated by applying the general principles of the selection index theory. The required genetic variances for the new traits, the economic weights for all breeding objective traits and the genetic correlations among the selection index traits were estimated within this study. The marginal economic weights, which were calculated for two-year-old cows by applying a bioeconomic model with implemented gene flow, were -193 and -168 € per case for clinical mastitis and overall claw disease incidence, respectively. Using the comprehensive selection index with 19 traits, the reduction in the incidence of both udder and claw diseases was calculated to be 0.004 cases per cow per year. At the same time, a more favourable genetic selection response was obtained for other functional traits, e.g., +0.020% for cow conception rate and +0.010 years for productive life of cow (which represented the profit of 67 € and 367 € per herd and per year, respectively) when compared to the current index. Based on this study, a direct selection of cows for claw and udder health is nowadays recommended to improve the health status of herds and economics in production systems.

The aim of the study was to determine what dosage of copper nanoparticles added in the form of a hydrocolloid to standard dietary supplementation with copper sulphate will increase the antioxidant potential in the liver and breast muscle of chickens. In total, 126 one-day-old Ross 308 chickens were assigned to 7 experimental groups of 18 birds each (3 replications of 6 individuals each). The basal-diet treatment did not receive nano-Cu. Experimental groups received nano-Cu (0.5, 1.0 or 1.5 mg/kg body weight per day) via a tube into the crop over three 3-day periods (days 8–10, 22–24 and 36–38) or three 7-day periods (days 8–14, 22–28 and 36–42). Dietary supplementation of chickens with nano-Cu to exceed the Cu level recommended by the NRC increased the content of Cu (P=0.042) while reducing that of Zn in the liver (P=0.031) and breast muscle (P=0.036). Supplementing the diet of chickens with nano-Cu to a level exceeding the level of copper recommended by the NRC by 7% to 25% increased the antioxidant potential of the liver and the breast meat. The study has shown that the antioxidant status of the liver and breast meat of chickens can be improved by supplementing the standard dietary copper sulphate supplement with the addition of nano-Cu, but to a level not exceeding 25% of the copper content recommended by NRC (1994) for broiler chickens, but the most safe is the nano-Cu level not exceeding 7% of the copper content recommended by NRC (1994).

The aim was to investigate the antimicrobial susceptibility of most frequently isolated streptococci from Czech dairy herds. A total of 3,719 quarter milk samples were collected and cultivated between January 2017 and June 2018 from cows with clinical or subclinical mastitis from 112 farms. Only one isolate of each species, collected from the same farm per six-month period, was included in the susceptibility testing. The susceptibilities of Streptococcus uberis (163 isolates) and S. dysgalactiae (25 isolates) to 10 antimicrobials (penicillin – PEN, amoxicillin/clavulanic acid – AMC, ceftiofur – EFT, clindamycin – CLI, gentamicin – GEN, streptomycin – STR, trimethoprim/sulfamethoxazole – SXT, enrofloxacin – ENR, tetracycline – TET, rifampicin – RIF) from 9 groups were determined by measuring their minimum inhibitory concentrations. The percentages of resistant S. uberis isolates to the antimicrobials were as follows: TET (63.2%), STR (52.1%), CLI (30.1%), and RIF (2.5%). Intermediate susceptibility was found to RIF (63.2%), PEN (35%), ENR (2.5%), EFT (1.8%), and AMC (1.2%). All the S. uberis isolates were susceptible to GEN and SXT (100%). However, only 6.7% of S. uberis isolates were susceptible to all tested antimicrobials, and 38.7% of isolates were multidrug resistant (≥ 3 groups of antimicrobials). All the S. dysgalactiae isolates were susceptible to PEN, AMC, EFT, GEN, SXT, and ENR (100%). Resistant S. dysgalactiae isolates were found to TET (60%), STR (28%), CLI (12%), and intermediate to TET (24%) and RIF (20%). Sixteen percent of S. dysgalactiae isolates were multidrug resistant. The relatively high occurrence of (multiple) resistance, relative to mastitis pathogens, highlights the importance of monitoring this condition in dairy herds.

This study aimed to investigate the effect of fractionated seminal plasma (SP) on boar sperm characteristics following cryopreservation. Gel filtration chromatography yielded two fractions: SP1 with more than 40 kDa (>40 kDa) and SP2 with less than 40 kDa (<40 kDa). The fractionated SP (SP1 and SP2), whole seminal plasma (wSP) and Beltsville Thawing Solution (BTS) were used for the treatment of semen before freezing-thawing. Besides the analysis of sperm motility characteristics, plasma membrane integrity (PMI), acrosome integrity, and viability (Vybrant Apoptosis Assay) were analyzed in pre-freeze and post-thaw (PT) semen. Among the analyzed pre-freeze sperm parameters, rapid movement was markedly affected by boar and treatment. Furthermore, boar and treatment were significant sources of variations in PT semen quality. Treatment with wSP caused a marked reduction in PT semen quality compared with BTS, SP1 or SP2. Wide variations in PT acrosome integrity and viability were observed in spermatozoa treated with BTS and the fractionated SP, being significantly higher in the SP1- and SP2-treated samples. However, PT semen quality did not differ between semen samples treated with SP1 and SP2. Representative electrophoretic profiles of sperm proteins from each treatment showed quantitative and qualitative differences, indicating varying effects of the cryopreservation procedure on the sperm membrane integrity. The findings of this study indicated that the cryoprotective effects of the SP components varied among boars and that different components of the fractionated SP exerted varying effects on sperm functions following cryopreservation. It could be suggested that the variable protective protein components of either fractionated SP ameliorated alterations in the sperm membranes during cryopreservation, resulting in reduced susceptibility to cryo-damage.

This study examined the effect of progesterone (P4) supplementation from Days 16 to 18 post-AI on interferon-stimulated gene (ISG) expression on Day 19 in high-producing dairy cows. Gene expression levels were measured in peripheral blood mononuclear cells. Possible relationships between ISG expression and the incidence of pregnancy failure were also investigated. Cows were alternately assigned on Day 16 post-AI to a control (C: n = 13) or treatment group (P4: n = 14). Out of 27 cows, 12 returned to oestrus before pregnancy diagnosis and 9 were diagnosed as pregnant on Day 28. ISG expression was assessed in all cows. Expression levels for the genes OAS1, ISG15, MX1 and MX2 were higher for pregnant than for non-pregnant cows (P=0.04; P<0.001; P=0.02; P=0.045; respectively). A significant (P=0.01) interaction was observed between the treatment and positive pregnancy diagnosis groups on Day 28 post-AI for the probability of showing ISG expression. This interaction suggests that in cows not pregnant on Day 28, P4 supplementation may have led to increased ISG15 mRNA expression on Day 19. Lower ISG15 expression was detected for cows returning to oestrus than for pregnant cows (P<0.001). However, cows with a negative pregnancy diagnosis showed intermediate values, differences being non-significant when compared to cows returning to oestrus or pregnant cows. Our results suggest that P4 supplementation during the pre-implantation period promotes conceptus signalling.

This study investigated the fertility of dairy cows during summer season after treatment with a single or double PGF_2α in a progesterone (P4)-based Ovsynch protocol for fixed-time artificial insemination (FTAI). The data were compared to a treatment effectuated during winter season. Two groups of 60 dairy cows each were randomly assigned on day 60 post-partum to single PGF_2α or double PGF_2α group. At removal of the P4 treatment the single PGF_2α group received a single dose and the double PGF_2α group received two doses of PGF_2α at 24 hours apart. In each group, 30 cows were treated during the summer (June, July and August) and 30 cows during the winter (December, January and February) season. During summer season a double PGF_2α dose did not influence pregnancy rate at FTAI but improved cumulative pregnancy rate 60 days after FTAI (43% vs 69% for single PGF_2α and double PGF_2α administration, respectively; P<0.05). During winter season the single or double PGF_2α administration did not modify PR or cumulative PR. In conclusion, during summer the utilization of a double instead of single PGF_2α treatment into a P4-based Ovsynch-FTAI protocol did not increase pregnancy rate at FTAI but improved cumulative pregnancy rate.

Artificial insemination (AI) and semen cryopreservation are the most accessible and commonly used techniques for breeding domestic animals. Among many parameters, such as plasma membrane integrity and acrosome structure, one of the key factors that determine the quality of frozen-thawed samples for artificial insemination is sperm motility. Sperm motility is one of the key parameters that determine the quality of frozen-thawed samples for AI. The total number of progressively motile spermatozoa in thawed canine semen is correlated with fertility. A variety of substances were used to compare sperm motility with the control. The aim of this study was to determine the effect of semen extender supplementation with motility stimulants, pentoxifylline (PTX), caffeine (CAF) and 2’-deoxyadenosine (DX), after different post-thaw incubation times (30, 60, 120 min) on the motility, selected kinematic parameters, plasma membrane integrity and mitochondrial membrane potential of cryopreserved canine spermatozoa. During attempts to improve the quality of cryopreserved semen, the applied substances exerted beneficial effects at a concentration of 10 mM. We demonstrated that both phosphodiesterase inhibitors, caffeine and pentoxifylline, as well as 2’-deoxyadenosine increased the motility and selected kinematic parameters of thawed canine spermatozoa.

A 71-day-long experiment was conducted to evaluate the inclusion of 20% Hermetia illucens (HI) meal; Tenebrio molitor (TM) meal; Gryllodes sigillatus (GS) meal; and Blatta lateralis (BL) meal in comparison to a control diet without any insect-based materials that used fish meal as the main source of protein. A total of 1950 rainbow trout juveniles (53.39 ± 3.74 g) were used. The formulated diets were isonitrogenous (45%) and isoenergetic (10 MJ kg⁻¹). The inclusion of a full-fat insect meal did not affect the survival rate during the experimental period. The growth performance was significantly improved in the BL and TM treatments, while in the HI treatment was not affected. However, the GS treatment had a negative effect on the growth performance. The villus height decreased in the TM and GS treatment groups and increased in the BL diet group. The total number of bacteria increased in all insect meal diet groups. The results of the experiment show that B. lateralis, T. molitor and H. illucens full-fat meals can be used as a partial fish meal replacement without negative effects on survival or growth performance parameters. Moreover, full-fat insect meals may be considered as a protein source and a functional feed component that may positively affect the histomorphological structure of the fish gastrointestinal tract and stimulate the expansion of beneficial bacterial populations in the gut.

The objective of this experiment was to test the effects of supplementation of defatted black soldier fly (Hermetia illucens) larvae (BSFL) meal in beagle dogs. A total of nine healthy female beagles (initial body weight 12.1 ± 1.76 kg) were fed grain-based diets with three levels of BSFL meal (0, 1% or 2%) in a 42-day feeding trial. At the end of week 6 of the experiment, all dogs were intraperitoneally challenged with Escherichia coli lipopolysaccharide (LPS) at 100 μg/kg of body weight. Albumin concentration was linearly increased with increasing BSFL meal level (P<0.05). A linear increase (P<0.05) in calcium concentration was observed when increasing dietary BSFL meal. Although dietary treatments did not affect the digestibility of ether extract, the digestibility of dry matter and crude protein were linearly increased with increasing the level of BSFL meal. The concentration of tumor necrosis factor-α was linearly decreased but glutathione peroxidase (GPx) concentration was linearly increased when increasing the level of BSFL meal at 6 h after challenge (P<0.05). In addition, there were quadratic increases in concentrations of GPx and superoxide dismutase with increasing dietary BSFL meal level at 3 h after challenge (P<0.05). These findings from the present study demonstrate that BSFL meal can be supplemented in the diet to convert beneficial effects to beagle dogs, indicated as improved digestibility of dry matter and crude protein and anti-inflammatory and anti-oxidative capacity.

This research aimed to study the effect of dietary eucalyptus (Eucalyptus camaldulensis) leaves powder (EL) on growth performance, blood parameters, immune response and caecal microbiota in 84 growing Jabali and V-Line rabbits raised under high environmental temperature. The experiment started at 10 weeks of age and lasted 6 weeks. Rabbits were randomly distributed into three dietary eucalyptus treatments; control (no EL) and two groups supplemented with 0.1% and 0.2% EL powder. Rabbits were weighed at the beginning and at the end of the experiment. Feed intake, weight gain and feed conversion ratio were determined. Cell-mediated immune response was evaluated. At the end of the experiment, 54 rabbits were slaughtered (nine rabbits/sub-group). The results showed that the high level of EL (0.2%) had a negative effect on growth performance, dressing %, mid part % and significantly increased cell-mediated response. Rabbits fed the high level of EL showed shortening in caecum length. Significant linear reduction of total bacterial count and E. coli was observed in both groups given either 0.1% or 0.2% EL compared to the control group. Similar trend was found in the percentage of Salmonella sp. detection in both breeds. Jabali rabbits were significantly heavier than V-line rabbits and had better FCR and carcass traits except for fore part %. Additionally, they showed lower total microbial count. The current study indicated that EL could be utilized as an effective feed additive to improve cellular immunity and to reduce caecal bacterial counts in rabbits raised under high ambient temperature.

The effect of dietary supplementation with a biotechnological extract of Ajuga reptans on growth performance, oxidative status and immune parameters was evaluated in post weaning piglets. At weaning, 120 piglets with an average live weight of 8.1±1.3 kg, were assigned to one of three experimental groups. The first group was fed a control diet (C). The second and third groups were fed the same diet supplemented with 5 mg (T1) and 10 mg (T2) of teupolioside/kg feed from a biotechnological plant extract. Growth performances were recorded and blood samples were collected at the beginning, at 14 days, and at the end of the trial (56 days). Serum biochemical parameters, oxidative status and immunoglobulin titres were determined. Average daily gain tended to be higher (P=0.057) and live weight was higher in piglets (P<0.05) fed with different amounts of plant extract (T1 and T2) than the controls. The production of reactive oxygen metabolites (ROMs) was higher (P<0.05) in the control group than in the groups receiving teupolioside (T1 and T2). Concentration of serum immunoglobulin of class G improved (P<0.001) in piglets fed the T1 and T2 diets than the controls. Overall, the results suggested that the biotechnological extract of Ajuga reptans containing teupolioside has an antioxidant and immunomodulant effect.

The aim of the research was to determine the affectivity of 4 different eubiotic preparations on the growth performance of pigs, microbial status, the integrity of intestinal mucosa, and some blood parameters. The experiment was conducted for 28 days on 48 male piglets allocated to six dietary treatments. Group 1 was offered a diet without eubiotic; 2 – a diet with acids mixture; 3 – phytobiotic, medium-chain fatty acids (MCFA) and yeast; 4 – probiotic, MCFA, and yeast; 5 – phytobiotic, probiotic, acids mixture, and sodium butyrate; 6 – phytobiotic, probiotic, MCFA, and sodium butyrate. The average daily weight gains and feed intake were recorded. Blood samples, digesta samples, and ileal tissue samples were collected for studies. There was no significant difference in gain, feed intake, or FCR among the treatments as well as in the ileal and caecal pH value, microbial content, and total SCFA content in caecal digesta. Ammonia content in ileal digesta was significantly higher in comparison with other groups and in caecal digesta was significantly higher in group 6 in comparison with groups 1 and 2. Villi height was significantly higher (P<0.05) in groups 2, 3 and 6 compared to the control. Villi height to crypt depth ratio was significantly higher (P<0.05) in groups 5 and 2, but the most promising effects seem to be from combinations 3 and 4. In comparison with control: in groups 2, 3 and 5 higher ALT, glucose and triglyceride; in groups 3, 4 and 5 higher total protein and cholesterol; in group 4 higher albumin and in group 6 higher BUN, were found. Generally, used eubiotic preparations affected gut morphology and some blood parameters but did not affect microbiota, pig growth or feed utilization.

The aim of this study was to evaluate the effects of evaporative cooling at two different frequencies per day on the respiration rate (RR) of lactating dairy cows, considering cow-related factors. Twenty multiparous Israeli Holstein dairy cows housed in a naturally ventilated cowshed were divided randomly into two treatment groups. The cows of both groups were exposed to 3 or 8 cooling sessions per day (3xcool vs. 8xcool, respectively). The RR was observed hourly, with a maximum of 12 measurements per day. Body posture (standing vs. lying) was simultaneously documented. Milk yield was recorded daily. Coat color was determined from a digital photograph. The RR of standing and lying cows was lower in the 8xcool group (60.2 and 51.6 breaths per min (bpm), respectively) than in the 3xcool group (73.1 and 65.6 bpm, respectively). For each increment of five kilograms of milk produced, RR increased by one bpm, and the RR of cows in early days in milk (DIM) was 12.3 bpm higher than that of cows in late DIM. In conclusion, eight cooling sessions per day instead of three lead to a RR abatement in heat-stressed cows under hot conditions, and cow-related factors directly impact the RR during heat stress assessment.

In recent years, consumers have increasingly sought niche food products with specific aroma and flavour, and rich in nutrients. With a growing demand for quality poultry products, there is an opportunity to increase production of capons, which are more and more often marketed as high quality products, because their meat is more delicate, tender and juicy. Therefore the objective of this study was to compare meat quality parameters and rate of protein degradation between capon and cockerel breast muscle during postmortem aging. Fibre type diameter, intact desmin and dystrophin contents at 15 min, 24 h, and 48 h postmortem and the following technological parameters of breast meat were also determined: pH₁₅, pH₂₄, pH₄₈, drip loss, shear force. The study was carried out on hybrids between Rhode Island Red cockerels (R-11) and Yellowleg Partridge hens (Ż-33) aged 24 weeks. The current findings indicate that compared with cockerel breast muscles, the capon breast muscles had significantly higher pH₁₅ (P≤0.01), and lower drip loss (P≤0.01) and shear force values (P≤0.05). Additionally, the intensity of intact desmin and dystrophin in capon breast samples at 24 h and 48 h postmortem was significantly lower (P≤0.05) than that in the cockerel breast sample. In turn, the lower rate of desmin and dystrophin degradation (P≤0.05), along with higher drip loss in cockerel compared to capon breast muscles, may account for their lower muscle fibre diameters at 24 h and 48 h postmortem. Moreover, the rate of early postmortem pH decline can partly explain the variation of desmin and dystrophin degradation.