Effects of caponisation on lipid and fatty acid composition of intramuscular and abdominal fat of medium-growth broilers

The effect of caponization on tibia bone histomorphometric properties of crossbred roosters

The negative effect of caponization on the structural, geometric and mechanical parameters of femur and tibia has been shown in a few studies. Nevertheless, its influence on tibia bone microarchitecture is still largely unknown. Therefore, this study aimed to assess the effect of castration on the microstructural parameters of the trabecular and compact bone of tibia bone in crossbred chickens. The experiment involved 96 roosters derived from crossing Yellowleg Partridge hens ([Formula: see text]-33) and Rhode Island Red cockerels (R-11) fattened until the 16th, 20th and 24th week of life. Animals were randomly divided into 2 groups of 48 each. Group I (control) consisted of intact roosters and group II (experimental) consisted of birds subjected to caponization at the 8th week of age. The castration surgery had no influence on some properties within compact bone such as osteon diameter On.Dm, osteon perimeter On.Pm, osteon area On.Ar, osteocyte lacunar number Ot.Lc.N, osteon bone area On.B.Ar, osteon wall thickness On.W.Th as well as thick-mature collagen content in all analyzed age groups of animals. Nevertheless, our results demonstrate that castration caused a decrease of Haversian canal area Hc.Ar, osteocyte lacunar area Ot.Lc.Ar and osteocyte lacunar porosity Ot.Lc.Po among the 16-week-old birds, decrease of Haversian canal perimeter Hc.Pm and increase of fraction of bone area On.B.Ar/On.Ar among 16- and 24-week-old individuals and also an increase of osteocyte lacunar density Ot.Lc.Dn in the osteons of the oldest roosters. Additionally, some microstructural parameters of trabecular bone show the negative effect of caponization. The youngest 16-week-old capons were characterized by thinnin the trabecular in the epiphysis part of tibia. Moreover, in the case of 24-week-old, there is an increase in the trabecular separation Tb.Sp with simultaneous decrease of trabecular number Tb.N compared to roosters, which may suggest the increase of the bone resorption among the oldest individuals. The increased bone turnover in the epiphysis part of the tibia bone also indicates changes in the collagen fibers distribution, where among 20-week-old animals there is a decrease in the content of immature thin collagen fibers with simultaneous increase in the content of mature thick collagen fibers. Furthermore, among the oldest 24-week-old individuals we can observe the increased thick-to-thin collagen ratio, which may be a sign of slowing down in bone formation.

Integrated LC/MS-based lipidomics and transcriptomics analyses revealed lipid composition heterogeneity between pectoralis intramuscular fat and abdominal fat and its regulatory mechanism in chicken

Intramuscular fat (IMF) content is conducive to multiple meat quality properties, while abdominal fat (AF) is treated as waste product in chicken industry. However, the heterogeneity and distinct regulatory mechanisms of lipid composition between the IMF and AF are still unclear. In this study, we carried out non-targeted lipidomics analyses of pectoralis IMF and AF, and detected a total of 423 differential lipid molecules (DLMs) between chicken IMF and AF, including 307 up-regulated and 116 down-regulated DLMs in pectoral IMF. These DLMs exhibited the definite alteration of lipid composition. The up-reglated DLMs in IMF were mainly glycerophospholipids (GPs), including the bulk of phosphatidylcholines (PC, PC (P) and PC (O)), phosphatidylethanolamines (PE, PE (P) and PE (O)), phosphatidylglycerols (PG) and phosphatidylinositol (PI), while the up-reglated DLMs in AF were mainly glycerolipids (GLs), including most of triacylglycerols (TG) and diacylglycerols (DG). We further identified 28 main DLMs contributing to the heterogeneous deposition of IMF and AF, including 11 TGs common to IMF and AF, 12 PCs/PC (P)s specific to IMF and 5 DGs specific to AF. Further integration of transcriptome with the main DLMs by weighted gene co-expression network analysis (WGCNA), we found five key gene sets that included 386 unique genes promoting IMF deposition in pectoralis, 213 unique genes promoting AF deposition, 6 unique genes detrimental to AF deposition, 7 common genes that promote IMF deposition in pectoralis while adversely affect AF deposition, and 28 genes that only promoted IMF deposition in pectoralis but had no effect on AF deposition. In addition, we also observed the expression characteristics of key genes in vivo and in vitro, and found that transmembrane protein family gene TMEM164 might be mainly involved in the positive regulation of intramuscular fat deposition in pectoralis and zinc finger protein family gene ZNF488 had a potential unique positive regulatory function on abdominal fat deposition. These findings provide new perspectives for understanding IMF and AF heterodeposition and will serve as a valuable information resource for improving meat quality via breeding selection in chicken.

The sex impact on the technological and chemical characteristics of meat derived from the Polish native chicken breed

The aim of the study was to evaluate the birds' sex as well as the caponisation influence on the technological traits of obtained meat, fatty acids profile as well as main chemical compounds distribution. In this study, 40 hens, roosters and green-legged partridge capons each were used (4 replications each). At 24 weeks of age, 2 birds from each replication subgroup were selected and slaughtered. During dissection analysis, pectoral and femoral muscles were sampled. Acidity, colour, tenderness, water holding capacity, drip and cooking loss were determined in the obtained material. The fatty acid profile of the meat was also determined, as well as the distribution of components in the pressed meat samples using FTIR spectroscopy. Statistically significant differences in the colour lightness index (L*) of the breast muscles were recorded, with cockerel meat being the darkest and capon meat the lightest. The greatest natural water loss was recorded in the hens' pectoral muscle; cooking loss was also the greatest in these samples. Roosters showed significantly the lowest content of monounsaturated fatty acids, at the same time the highest proportion of the n3 fatty acids group was found in capons. Irrespective of muscle, meat from roosters showed the highest susceptibility to oxidation (PI index). The variation in the chemical composition of the meat was confirmed by FTIR mapping.

Physicochemical characteristics of meat from capons derived from the crossing of conserved breed hens and meat roosters

The study aimed to determine the effect of castration on physicochemical properties of meat from capons derived from the crossing of Rhode Island Red (R-11) hens and meat roosters. Subjects were 100 crossbred cockerels, which were randomly assigned to 2 groups of 50 each. Group I (control) consisted of intact cockerels and birds from group II were subjected to castration. The castration was performed at 7 wk of age under local anesthesia by a veterinarian. All birds were fed ad libitum with the same feed mixtures and placed on litter under optimal environmental conditions at a stocking density of 5 birds/m². At the end of fattening (20 wk of age), 10 birds whose body weight was similar to group average, were selected from each group for slaughter. After slaughter, the birds were analyzed for dressing percentage and physicochemical parameters of breast and leg muscles, which were subjected to sensory evaluation. The results demonstrated that compared to intact cockerels, capons were characterized by significantly higher body weight, dressing percentage and carcass muscle content. Both the breast and leg muscles of the capons showed better physicochemical parameters and higher sensory score. It is therefore concluded that the birds derived from the crossing of Rhode Island Red (R-11) hens and meat roosters are good material for capon production, their meat is a product of distinctly higher quality.

The Influence of Sex on the Slaughter Parameters and Selected Blood Indices of Greenleg Partridge, Polish Native Breed of Hens

The aim of the study was to assess the influence of sex, including caponization, on selected physiological and productive traits of Greenleg partridge (GP) birds. The study material consisted of 120 GP chicks (40 females and 80 males), divided into 3 equal groups (4 replication in each) and kept in litter system and fed ad libitum. A total of 40 cocks have been surgically castrated. The body weight (BW) of birds were measured biweekly. At the age of 24 weeks 8 birds/group were slaughtered, their carcasses were subjected to simplified dissection. Blood samples were collected and among others biochemical profile of serum was established. The lowest BW, regardless of age, had hens. From 18th week capons had the highest BW and finally it was similar to cocks. Cocks demonstrated, significantly, the highest carcass yield, however, the biggest proportion of breast muscles were stated in capons carcasses. The effect of sex is very clear in case of abdominal fat pad. The highest proportion of it was found in females but the lack of sex hormones in capons also contributed to a higher fat accumulation. The serum profile showed that the sexual maturity of hens increased lipids content (cholesterol, trigliceroles) caused by laying production.

Effects of Caponization on Growth Performance and Meat Physicochemical Properties of Crossbred Chickens

The aim of the study was to determine the effect of caponizing on body weight and physicochemical properties of meat of the capons – hybrids obtained from the crossing of hens of the Yellowleg Partridge (Ż-33) breed with meat roosters. The study covered 80 hybrid roosters, which were randomly assigned to two groups of 40 animals each (8 boxes of 10 birds in each group). Group I (control) consisted of uncastrated roosters while group II included birds, which were castrated at 8 weeks of age under local anaesthesia by a vet. Birds were fed ad libitum with the same standard diets and kept on litter under optimal environmental conditions with a stocking density of 7 animals/ m2. At the end of fattening, i.e. in the 20th week of life, 8 birds with a body weight close to the group average were selected from each group for slaughter. After slaughter, the effectiveness of the procedure was checked (lack of testicles), then the slaughter performance of birds, physicochemical parameters of the pectoral and leg muscles were determined, and sensory evaluation was performed. The procedure of castration of hybrid roosters had a positive effect on body weight, feed conversion ratio and carcass traits. The pectoral and leg muscles of the capons were characterized by better water absorption, tenderness and sensory evaluation compared to roosters. Among the assessed groups of birds there was also a variation in the colouring of whole carcasses and muscles, which were lighter (L*), more yellow (b*) and less red (a*) in caponized birds. In addition, the castration procedure had a positive effect on the total protein content in both the pectoral and leg muscles, which in turn, with a higher raw fat content, were distinguished by a favourable ratio of n-6/n-3 polyunsaturated fatty acids (PUFA). Based on the results, it can be concluded that the hybrids obtained from the crossbreeding of the Yellowleg Partridge (Ż-33) and Ross 308 meat roosters are good choice for capon production. They can complement poultry meat production with a niche product for consumers looking for products of exceptional quality.

Improvac induces immunocastration by affecting testosterone levels and disrupting spermatogenesis in male broiler chickens

Immunocastration (vaccination against Gonadotropin-releasing hormone (GnRH)) has been regarded as a friendly substitution to physical castration in animals. To date, a few studies have reported the use of Improvac for immunocastration in boar and one study in broiler chickens; however, there is an apparent dearth of scientific evidence regarding the application of Improvac for immunocastration in birds. In the present study, we evaluated the effects of Improvac-based immunocastration on testosterone levels and spermatogenesis in broiler chickens and the effects of Improvac on the expression of genes related to testosterone biosynthesis and metabolism as well as spermatogenesis. The birds were randomly divided into 4 groups (n = 30 each): Control group (non-immunized), Early group (immunized with Improvac at week 3), Late group (immunized with Improvac at week 6), and Early + Late group (immunized with Improvac at weeks 3 and 6). Immunization with Improvac significantly improved the average daily gain compared to the Control group. Of note, following Improvac vaccination, the reproductive efficiency was significantly decreased in male broiler chickens. Furthermore, parameters such as the serum testosterone concentration, spermatogenesis, and the expression levels of genes related to testosterone metabolism (Cyp17A1, Cyp19, HSD3B1, and HSD17B3) and spermatogenesis (Cyclin A1 and Cyclin A2) were significantly reduced in the immunized groups compared to the Control group. Taken together, these findings reveal that immunization against GnRH can be achieved, at least partially, in male broiler chickens. The results of our study also support the hypothesis of using Improvac as an alternative solution to caponization, with considerably improved animal welfare.

Effect of immunocastration and caponization on fatty acid composition of male chicken meat

Recently, immunocastration with Improvac (ImmC). has been tested in broilers and a considerable reduction in serum testosterone concentration (reduced by 79% compared to roosters) was observed. The aim of this study was to evaluate the effect of immunocastration on meat fatty acid (FA) composition and its comparison with caponized and intact males (roosters). The study was conducted with 3 experimental groups: control group (roosters), the group of birds submitted to surgical caponization (SurgC), and the group of birds submitted to immunocastration with Improvac. The comparison of breast meat partial FA sums of castrated (SurgC and ImmC) with control birds (roosters) revealed that castrated birds showed significantly higher content of n-3 polyunsaturated fatty acids (n-3 PUFA) than control birds (1.76 vs. 1.46 g/100 g of total FA; superiority of 20.2%), which has contributed to the occurrence of significant differences on both the n-6/n-3 ratio and the atherogenicity index (AI). In contrast, on leg meat portion, castrated birds displayed higher contents of both total saturated and monounsaturated fatty acids (SFA and MUFA, with 2.2 and 4.1% more, respectively) and lower total n-6 PUFA content (8.3% less) than was observed in control birds, which contributed to significant differences in the AI index. On the other hand, the comparison of breast meat portion from SurgC with ImmC showed that immunocastration contributed to lower total SFA and higher total n-6 PUFA, which have contributed to significant differences on both Polyunsaturated/Saturated (P/S) and n-6/n-3 ratios. Whereas, on leg meat portion no significant differences were observed on partial sums and a single difference was observed on the thrombogenicity index. Immunocastration of broilers has contributed to minor changes in the FA profile, but has improved the overall lipid quality indexes in both breast and leg meat portions. Therefore, immunocastration could be applied as an alternative method to caponization without negative consequences in meat FA profile.

Postmortem Degradation of Desmin and Dystrophin in Breast Muscles from Capons and Cockerels

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.

Three-Point Scale of Lipid Concentration and Localization in Muscle Tissue of Birds Using Oil Red O Staining

Research on skeletal muscles includes chemical, sensorial, histopathological, microbiological analysis, and the influence of observed data on meat quality. The aim of this paper was to establish a point scale for analysing the fat concentration in breast and thigh muscles of birds during histological examination. The need for a point scale showing lipid localization arises during the experiment, including the castration of the bird. During necropsy, pectoral and thigh muscles were put into 30% saccharose solution with the addition of sodium azide. Then, frozen samples were cut into 8 µm sections and stained with Oil Red O (Bio-Optica, Milan, Italy) to detect lipids. Four main locations were evaluated: the area around vessels, perimysium between fascicles, endomysium between fascicles, and sarcoplasm of the fibres. Each location was separately evaluated for pectoral and thigh muscles. The percentage of tissue occupied by lipids in different locations was detected using Panoramic Viewer software (3DHISTECH, Budapest, Hungary). The results from the point scale analysis, similar in pectoral and thigh muscles, confirmed data from the chemical analysis. Significant differences were observed in all examined periods in chemical analysis (P<0.05) and were visible in the point scale with a higher number of birds with higher lipid concentration in all examined locations. Our scale analysis of lipid concentration, confirmed by chemical analysis, is an objective tool and can be used separately in muscle tissues in experiments where there is the need for lipid visualization. An established three-point scale can be a tool in poultry muscle tissue evaluation because not only accumulation but also lipid location is crucial in determining the usefulness of meat in culinary processing.

Weighted gene coexpression network analysis identifies specific transcriptional modules and hub genes related to intramuscular fat traits in chicken breast muscle

Intramuscular fat (IMF) traits are important factors that influence meat quality. However, the molecular regulatory mechanisms that underlie this trait in chickens are still poorly understood at the gene coexpression level. Here, we performed a weighted gene coexpression network analysis between IMF traits and transcriptome profile in breast muscle in the Chinese domestic Gushi chicken breed at 6, 14, 22, and 30 weeks. A total of 26 coexpressed gene modules were identified. Six modules, which included the dark gray, purple, cyan, pink, light cyan, and blue modules, showed a significant positive correlation (P < 0.05) with IMF traits. The strongest correlation was observed between the dark gray module and IMF content (r = 0.85; P = 4e-04) and between the blue module and different fatty acid content (r = 0.87~0.91; P = 5e-05~2e-04). Enrichment analysis showed that the enrichment of biological processes, such as fatty acid metabolic process, fat cell differentiation, acylglycerol metabolic process, and glycerolipid metabolism were significantly different in the six modules. In addition, the 32, 24, 4, 7, 6, and 25 hub genes were identified from the blue, pink, light cyan, cyan, dark gray, and purple modules, respectively. These hub genes are involved in multiple links to fatty acid metabolism, phospholipid metabolism, cholesterol metabolism, diverse cellular behaviors, and cell events. These results provide novel insights into the molecular regulatory mechanisms for IMF-related traits in chicken and may also help to uncover the formation mechanism for excellent meat quality traits in local breeds of Chinese chicken.

Effects of caponization and age on the histology, lipid localization, and fiber diameter in muscles from Leghorn cockerels

Poultry researchers seek general and native lines of birds for capon production. The primary aim is to find high-quality meat with valuable sensory attributes. Castration decreases androgen levels and changes lipid metabolism, resulting in the accumulation of abdominal, subcutaneous, and intramuscular fat, which changes the flavor, texture, and tenderness of the meat. Histological analysis of selected skeletal muscles from Leghorn capons and cockerels was the main aim of the present study, along with examination of lipid localization in muscle tissue. We also assessed fiber type and diameter in the pectoral muscles (pectoralis major). The experiment was performed on 200 Leghorn cockerels; testes were removed at 8 wk of age. At 12, 16, 20, 24, and 28 wk of age, 6 cockerels and 6 capons were slaughtered, and samples from the pectoral and thigh muscles were evaluated. Differences in the focal necrosis of the fibers with infiltration of lymphoid cells (P < 0.05) were observed in thigh muscles, with higher numbers in cockerels than in capons. All examined locations in the pectoral and thigh muscles of capons (around the blood vessels, in the perimysium, in the endomysium, and in the sarcoplasm) showed higher concentrations of lipids compared to levels in cockerels. The analysis of fiber type in pectoralis major muscles revealed that all fibers were type IIB. The diameters of the fibers of the pectoral muscles were different (P < 0.05) at 28 wk of age, and the diameters of the giant fibers were different (P < 0.05) at 16 wk of age. The high concentration of lipids in the skeletal muscles of Leghorn capons is remarkable. Thus, ethical reasons as well as economic reasons should be considered when one-day-old cockerels are eliminated.

Effects of caponisation and age on the histology of the internal organs of Leghorn cockerels

1. Poultry researchers seek the most efficient bird line to produce capons (castrated cockerels). The previous studies did not include results from histopathological analyses of internal organs after caponisation. No data have been published on whether adipose tissue accumulates in internal organs or if caponisation changes the structure of the lymphoid organs and the accumulation of lymphoid cells. 2. The aim of this study was to analyse the occurrence of histopathological lesions in internal organs from Leghorn (layer-type) capons and cockerels at different times of fattening. 3. Two hundred, one-day-old Leghorn cockerels were used in this experiment. At 8 weeks of age, the birds were randomly divided into a control group (100 uncastrated cockerels) and a second group consisting of 100 castrated birds. At 12, 16, 20, 24 and 28 weeks of age, six cockerels and six capons were slaughtered. Samples of all internal organs from six cockerels and six capons at each slaughter age were evaluated. 4. The main histopathological differences between capons and cockerels were related to the accumulation of adipose tissue, with higher values noted in capons, especially in the gizzard and the caecum submucosa and fatty degeneration in liver hepatocytes. 5. Additionally, differences were observed more often in cockerels than in capons with regard to depletion of lymphoid cells in lymphoid organs, including the thymus and bursa of Fabricius in 28-week-old birds and the spleen in 24-week-old birds. 6. These studies prove that caponisation causes the accumulation of fat in internal organs and changes the structure of lymphoid organs. 7. Age influences the occurrence of desirable lesions, such as the accumulation of adipose tissue within the examined organs, and older capons (24 and 28 weeks old) are better sources of high quality, potentially edible tissues.

Effects of caponization and age on the histology, lipid localization, and fiber diameter in muscles from Greenleg Partridge cockerels

The preference of modern consumers for high-quality meat has forced breeders to use native breeds to produce capons. Caponization, both chemical and surgical, leads to androgen deficiency and changes in lipid metabolism and results in the accumulation of abdominal, subcutaneous, and intramuscular lipids, which change the sensory values of the meat. The aim of this study was to histologically evaluate selected skeletal muscles from Greenleg Partridge capons and cockerels. We examined lipid localization in the muscular tissue and also assessed both fiber type and fiber diameter in the pectoral muscles. The experiment was performed on 200 Greenleg Partridge cockerels and testes were removed at 8 wk of age. At 12, 16, 20, 24, and 28 wk of age, 6 cockerels and 6 capons were slaughtered, and samples from the pectoral and thigh muscles were evaluated. Our histopathological evaluation revealed only minimal changes, and no significant differences between capons and cockerels were observed. The pectoral and thigh muscles of the capons had higher concentrations of lipids around the blood vessels, in the perimysium, in the endomysium, and in the sarcoplasm. The analysis of fiber type in the Pectoralis major muscles revealed that the fibers were all the IIB type. The diameters of the fibers of the pectoral muscles were significantly different (P < 0.05) at 20, 24, and 28 wk of age, and diameters of the giant fibers were significantly different (P < 0.05) at 24 and 28 wk of age. High concentrations of lipids in the meat of the capons is undesirable due to health-related reasons. However, the ability of adipose tissue to improve the sensory values of meat will always be a major quality of native/traditional products.

Effects of dietary fats on egg quality and lipid parameters in serum and yolks of Shan Partridge Duck

The effects of different dietary fats with variable levels of polyunsaturated fatty acids (PUFAs) on egg quality of Shan Partridge Duck, serum, and yolk lipid parameters were examined in this study. A flock of 585 optimal produced ducks were selected and diets enriched with 0.5%, 1%, or 2% fish oil (F)/flaxseed oil (FL)/rapeseed oil (R)/tallow (T) plus basal diet were supplied through a 28-d period. Supplemental fat source and fat level had no effects on egg qualities. Proportions of yolk total cholesterol (TC), saturated fatty acids (SFAs), monounsaturated fatty acids (MUFAs) were reduced (P < 0.001), while polyunsaturated fatty acids (PUFAs), ω-6 polyunsaturated fatty acids (n-6 PUFAs), ω-3 polyunsaturated fatty acids (n-3 PUFAs), Docosahexaenoic Acid (DHA), and Eicosapentaenoic Acid (EPA) were increased by fish oil, flaxseed oil, or rapeseed oil. Effects of supplementation increasing DHA and EPA were detected in F, FL, and R. Compared with C, fish oil significantly increased low-density lipoprotein cholesterol (LDL-C) in serum, flaxseed oil significantly reduced TC and increased very low-density lipoprotein cholesterol (VLDL-C), rapeseed oil significantly reduced TC and LDL-C in serum and increased VLDL-C, tallow significantly increased LDL-C. It is concluded that unsaturated fatty acids rich diets (fish oil, flaxseed oil, and rapeseed oil) might increase yolk PUFAs, reduce yolk cholesterol, and change serum lipid parameters without evident effect on egg qualities.

Decreased testosterone levels after caponization leads to abdominal fat deposition in chickens

BACKGROUND

Caponization results in reduced androgen levels, which leads to abdominal fat accumulation in capons. In this study, we sought to understand the molecular mechanisms behind this fat accumulation.

RESULTS

Abdominal fat (AF) content increased significantly (P < 0.05) and serum and AF testosterone levels decreased significantly (P < 0.05 or P < 0.01) after caponization. In AF tissue, 90 differentially expressed genes related to lipid metabolism were screened by gene expression profiling in caponized and sham-treated chickens. Among these, six representative genes were significantly up-regulated (APOA1, SCD, FABP7, RXRG, and FADS2) or down-regulated (FABP3) (P < 0.05 or P < 0.01) and were strongly associated with the PPAR pathway. In addition, cell junction pathways were also enriched. In vitro, Fat content was significantly lower in cells treated with testosterone compared with control cells (P < 0.01), and mRNA levels of RXRG, FABP7, and FABP3 changed accordingly, confirming the effect of testosterone on fat deposition.

CONCLUSIONS

The results of this study indicate that testosterone reduction likely regulates gene expression through PPAR and cell junction pathways resulting in increased fat accumulation. These results provide increase our understanding of the biological mechanisms by which caponization induces greater fat accumulation.

The analysis of meat and bone traits of Plymouth Rock cockerels and capons (P55) at different age

The aim of the study was the comparison of Plymouth Rock cockerels and capons and the evaluation of the influence of their age on slaughter yield, meat quality, and bone traits. The studies were conducted on cockerels and capons from P55 strain (Plymouth Rock). At 16, 18, and 20 wk of rearing, a dissection of whole carcasses of cockerels and capons was conducted, and breast and leg muscles were evaluated in terms of the physical and chemical traits, as well as the chemical composition. Also, traits of femur and tibia bones were studied. It was indicated that capons were characterized by a higher body weight (BW) before slaughter and higher weight of the eviscerated carcass than cockerels at consecutive dates of slaughter. Based on BW, the slaughter yield and muscle content of carcasses, it was found that the most optimal slaughter time in Plymouth Rock cockerels is at 18 wk and capons at 20 wk. It was observed that caponization had a significant effect on the chemical composition of breast muscles with respect to water and protein content. Along with bird age, collagen content in muscles decreased; however, significant differences were observed only in capons. At consecutive dates of evaluating cockerels, resistance and toughness of their femur and tibia bones increased significantly. Significant changes in the physical characteristics of bones were also found.

Accumulation of α-hexabromocyclododecane (α-HBCDD) in tissues of fast- and slow-growing broilers (Gallus domesticus)

The aim of the current study was to describe the fate of ingested α-hexabromocyclododecane (α-HBCDD) in fast-growing (FG) and slow-growing (SG) broilers, through an exposure to a dietary concentration of 50 ng α-HBCDD g^-1 feed during 42 and 84 days, respectively. Depuration parameters were assessed in SG broilers successively exposed during 42 days and depurated during 42 days. At market age, SG broilers had ingested 42% more feed than FG broilers, while their body weight gain per g of feed ingested was 34% lower. No isomerization of α- to β- or γ-HBCDD forms occurred, while OH-HBCDD was identified as a product of α-HBCDD metabolism. Irrespective of the strain, abdominal fat displayed the highest α-HBCDD concentration on a lipid weight basis, followed leg muscles and then breast muscle, liver and plasma. The accumulation ratios of α-HBCDD were slightly higher in SG (6.7, 2.1, 2.6 and 9.9 in leg muscles, breast muscle, liver and abdominal fat, respectively) than in FG broilers (5.2, 2.2, 1.1 and 8.4, respectively). The elimination half-lives in SG broilers were 20, 12 and 19 d in leg muscles, breast muscle and abdominal fat, respectively, to which dilution through growth contributed for around 50%. The overall assimilation efficiency of α-HBCDD was estimated at 58 and 50% in FG and SG broilers, respectively, while 22 and 17% of α-HBCDD ingested were estimated to be eliminated in excreta as metabolites.

Physicochemical composition and sensory quality evaluation of capon and rooster meat

The aim of the present study was to evaluate the effect of caponization on the physicochemical and sensory characteristics of rooster and capon meat (2 Portuguese autochthonous chicken breeds of roosters:Amarela and Pedrês), raised under the same production. The birds were castrated at 9 wk of age and bred until 140 d of age. Forty Amarela (20 roosters and 20 capons-castrated male) and 40 Pedrês Portuguesa (20 roosters and 20 capons) breed chickens, 5 free-range chickens, and 5 broilers were used. From the breast, leg, and wing muscles, physicochemical parameters such as pH, water activity (aw), physical color, moisture content, ash, CP, pigments, collagen, and total fat and fatty acids profile, were analyzed according to standard procedures. Caponization did not affect pH, aw, lightness (L*), yellowness (b*), ash, protein, collagen, saturated fatty acids (SFA), polyunsaturated fatty acids (PUFA), and the ratio of unsaturated fatty acids (UFA)/SFA. Results show that caponization decreased (P≤0.05) moisture content and increased (P≤0.05) pigments and intramuscular fat content. Capons showed higher (P≤0.001) redness (a*) and chroma (C*), and lower (P≤0.001) hue (H*) compared to roosters. Caponization increased (P≤0.05) monounsaturated fatty acids content and PUFA/SFA. The main fatty acids found were oleic (C18:1), palmitic (C16:0), and linoleic (C18:2). Capons had greater (P≤ 0.05) C18:1 content but lower (P≤0.01) butyric acid (C4:0), caprylic acid (C8:0), stearic acid (C18:0), and (P≤0.05) arachidonic acid (C20.4) content than roosters. The objective of sensory analysis was making the comparison of the Amarela and Pedrêsmeat with a free-range chicken and a broiler. Panelists classified the capon meat (Amarela and Pedrês) as juicier and less tough and fibrous than rooster meat. Broilers were in general juicier, tenderer, and less fibrous than the other chickens in this study. The results of sensory evaluation complement those obtained in physicochemical analysis, suggesting that caponization promotes an overall improvement in meat quality.

The analysis of meat traits of Sussex cockerels and capons (S11) at different ages

The aim of the study was to compare Sussex cockerels and capons as well as to estimate the influence of age on slaughter yield and meat quality. The tests were performed on cockerels and capons from strain S11 (Sussex). At 16, 18, and 20 wk of age, a dissection of the entire carcass was conducted. The breast and leg muscles were tested for physio-chemical traits, as well as chemical parameters. It was noted that, due to significant differences in BW of the eviscerated carcasses between wk 18 and 20 of slaughter, the best time to cease rearing S11 cockerels could be wk 20. However, for S11 capons, the optimal time for slaughter appeared to be wk 18 (no significant differences in BW and carcass weight or musculature between wk 18 and 20). The trait which did not differ between cockerels and capons slaughtered at different ages was slaughter yield. Fatness of the cockerels increased with age whilst the weight of capons' skin with subcutaneous fat was the same at wk 18 and 20 of evaluation. With increasing age, pH indicators of cockerels and capons' breast muscles were increasing; the water holding capacity of capons' breast muscles were also increasing. Both cockerels and capons showed darker color of breast muscle at wk 20 compared to wk 16 of evaluation. Redness of the breast muscle in the following periods of evaluation did not show significant differences, although with age, the yellowness of the cockerels and capons' breast muscle increased significantly. Among cockerels and capons, the water content in the breast and leg muscles were decreasing with age whilst the protein content was increasing. A significant growing tendency of the percentage of fat share in the breast and leg muscles with age was noted in the capon group. Conclusions for breeding practice are as follows: due to meat and quality traits, Sussex cockerels and capons can be used until wk 18 or 20 of life.

On the Combined Application of Iatroscan TLC-FID and GC-FID to Identify Total, Neutral, and Polar Lipids and Their Fatty Acids Extracted from Foods

An efficient separation and quantification of the individual neutral and polar lipid classes and their constituent fatty acids was achieved by the combination of two different detection techniques: Iatroscan TLC-FID and GC-FID. The solvent composition and ratio of development system, the sample size, the fidelity, and precision were tested in order to estimate the effectiveness of separation of individual neutral and polar lipid classes and the quantitative reproducibility of the Iatroscan TLC-FID technique. GC-FID method, with a high-quality capillary column, allowed sensitive and reproducible fatty acid qualitative and quantitative analyses, separation of fatty acid structural isomers (e.g., n-C16:0, iso-C16:0 and anteiso-C16:0), positional isomers (e.g., C18:1ω-9 and C18:1ω-7), geometrical isomers (cis-trans), and homologues (e.g., C16:0, C17:0, C18:0, etc.) in standards and complex lipid samples. Seventeen (17) lipid classes and fifty-two (52) saturated (SFA), monounsaturated (MUFA), and polyunsaturated (PUFA) fatty acids were identified and quantified, respectively, in samples of standard lipid and fatty acid mixtures, simulating the composition of natural lipids and their fatty acid methyl esters in common foods. The wide number of applications establishes this combination of Iatroscan TLC-FID and GC-FID methods as a powerful tool for lipid class and fatty acid analysis of any fat origin.