Performance and meat quality traits of slow-growing chickens stimulated in ovo with galactooligosaccharides and exposed to heat stress.

In vivo performance, carcass and meat quality traits of slow-growing chickens stimulated in ovo with trans galactooligosaccharides (GOS) and exposed to heat stress were evaluated. On d 12 of egg incubation, 3,000 fertilized eggs (Hubbard JA57) were divided into prebiotic group (GOS) injected with 3.5 mg GOS/egg, saline group (S) injected with physiological saline (only to assess the hatchability rate) and an uninjected control group (C). After hatching, 600 male chicks (300 from GOS and 300 from C) were housed on floor pens (6 pens/treatment, 25 birds/pen) and reared under neutral (TN) or heat stress conditions (HS, 30°C from 36 to 50 d). BW, daily feed intake (DFI), daily weight gain (DWG), feed conversion rate (FCR), and mortality were measured. At 50 d of age, 15 randomly selected birds/treatment/environmental conditions were slaughtered and the pectoral muscle (PM) was collected for analyses. Hatchability was similar among groups. BW of the newly hatched chicks was lower (P < 0.01) in GOS compared to C. Final BW, DWG, DFI, and FCR were not affected (P > 0.05) by GOS. HS reduced final BW (-12.93%, P < 0.001). During finisher phase, DFI and DWG were lower (P < 0.001) and FCR was higher (P < 0.01) in HS compared to TN. Mortality was not affected (P > 0.05) by GOS and HS. Meat from GOS chickens had a higher (P < 0.01) pH and was darker (P < 0.05) compared to C. Proximate composition, cholesterol content, fatty acid profile, and intramuscular collagen properties of PM were not affected by GOS. The HS group showed a lower (P < 0.05) content of both collagen and monounsaturated fatty acids than TN group. Significant interactions between GOS and temperature were found for FA composition. In conclusion, the differences in performance have had an impact on the responses to HS in Hubbard chickens, but not on mortality rate. GOS did not relieve the negative effect of HS on chickens' performance.

Impact of galactooligosaccharides delivered in ovo on mitigating negative effects of heat stress on performance and welfare of broilers.

Galactooligosaccharides (GOS) delivered in ovo improve intestinal health of broiler chickens. This study aimed to demonstrate the impact of in ovo stimulation with GOS prebiotic on day 12 of egg incubation on performance and welfare traits in broiler chickens. The incubating eggs were divided into 3 groups, based on the substance injected in ovo: 3.5 mg of GOS dissolved in 0.2 mL physiological saline (GOS), 0.2 mL physiological saline (S), or uninjected controls (C). Constant heat stress (HS) was induced on days 32 to 42 post-hatch by increasing environmental temperature to 30°C. Thermoneutral (TN) animals were kept at 25°C. The performance (body weight [BW], daily feed intake [DFI], daily weight gain [DWG], and feed conversion rate [FCR]) were measured and mortality was scored for starter (days 0 to 13), grower (days 14 to 27), and finisher (days 28 to 42) feeding phases. Rectal temperature was scored on days 32 to 42. Food-pad dermatitis (FPD) was scored post-mortem (day 42). GOS increased (P < 0.01) BW on day 42 (2.892 kg in GOS vs. 2.758 kg in C). Heat stress significantly reduced (P < 0.01) final BW (2.516 kg in TN vs. 3.110 kg in HS). During finisher phase, DFI was significantly higher in GOS vs. C (173.2 g vs. 165.7 g; P < 0.05). FCR calculated for the entire rearing period (days 0 to 42) ranged from 1.701 in C to 1.653 in GOS (P < 0.05). GOS improved FCR in HS animals during finisher phase (P < 0.05). Rectal temperature of GOS chickens under HS reached 42.5°C 1 day earlier than C and S (P < 0.05), which suggests that those birds recovered earlier from the high environmental temperature. Heat stress increased (P < 0.05) mortality about 5 times compared to TN during finisher phase (from 1.59% in TN to 7.69% in HS). GOS decreased FPD in TN conditions by 20% (no lesions in 81% in GOS vs. 60% in C). GOS delivered in ovo mitigated negative effects of HS on performance and welfare in broiler chickens.

Effect of galactooligosaccharides delivered in ovo on meat quality traits of broiler chickens exposed to heat stress.

A study was carried out to evaluate meat quality traits in fast-growing chickens stimulated in ovo with trans-galactoolighosaccarides (GOS) and exposed to heat stress. On day 12 of egg incubation, 3,000 fertilized eggs (Ross 308) were divided into prebiotic group (GOS) injected with 3.5 mg GOS/egg, saline group (S) injected with physiological saline, and control group (C) uninjected. After hatching, 900 male chicks (300 chicks/treatment) were reared in floor pens in either thermoneutral (TN; 6 pens/group, 25 birds/pen) or heat stress conditions (HS, 30°C from 32 to 42 D; 6 pens/group, 25 birds/pen). At 42 D of age, 15 randomly chosen birds/treatment/temperature were slaughtered and the pectoral muscle (PM) was removed for analyses. Data were analyzed by GLM in a 3 × 2 factorial design. In ovo treatment had no effect on PM weight, pH, water-holding capacity, and shear force. GOS and S birds had lighter (L*, P < 0.01) PM than C group, whereas the latter showed a higher (P < 0.05) yellowness index (b*) compared to S group. Proximate composition, cholesterol, and intramuscular collagen properties were not affected by treatment. As for fatty acid composition, only total polyunsaturated fatty acids (PUFA) content and n-6 PUFA were slightly lower in GOS group compared to S. Heat stress had a detrimental effect on PM weight (P < 0.01) and increased meat pH (P < 0.01). PM from HS chickens was darker with a higher b* index (P < 0.05) and had a higher (P < 0.01) lipid content and a lower (P < 0.05) total collagen amount. Total saturated fatty acids (SFA), monounsaturated fatty acids (MUFA), and PUFA were similar among groups. Significant interactions between factors were found for fatty acid composition: GOS decreased (P < 0.01) SFA and increased (P < 0.05) MUFA contents in HS birds. In conclusion, in ovo injection of GOS could mitigate the detrimental effect of heat stress on some meat quality traits.

Effects of in ovo injection of prebiotics and synbiotics on the productive performance and microstructural features of the superficial pectoral muscle in broiler chickens.

The aim of the study was to compare the effects of 2 prebiotics and 2 synbiotics injected in ovo on productivity parameters, quality, and microstructure of the superficial pectoral muscle in 35-day-old broiler chickens. On day 12 of incubation, 9,000 eggs Ross 308 were randomly divided into 5 experimental groups treated with different bioactives in ovo injected: C, control with physiological saline; PI, with 1.760 mg inulin; PB, with 0.528 mg of commercial prebiotic Bi2tos; SI, with 1.760 mg inulin and 1,000 CFU Lactococcus lactis spp. lactis IBB SL1; SB, with 0.528 mg Bi2tos and 1,000 CFU Lactococcus lactis spp. cremoris IBB SC1. The synbiotic solution contained 20 µl bacterial suspension and 180 µl prebiotic solution. For productive parameters and further tests ten male birds for each experimental group were used. The birds were slaughtered on day 35 of age. At slaughter, samples of the left pectoral muscles were taken and preserved by freezing in liquid nitrogen. The pH and color of the meat were evaluated at 45 min and 24 h post-mortem. Water holding capacity (WHC) was measured and expressed as the percentage of free water in meat. Microscopic specimens were analysed using MultiScan software for the measurement of the percentage of oxidative and glycolytic fibres and mean diameter of the muscle fibres. In ovo injection of prebiotics Bi2tos had a positive effect on body weight. In prebiotic group (PI) a negative impact on hatchability was observed. Prebiotics and synbiotics had no influence on the yield of the carcass and pectoral muscle. Bioactive compounds had a significant effect on the quality of meat parameters such as: pH 24 h (PI and PB group), L* 45' (SI and SB group), and WHC (groups PB, SI, and SB). The analysis of the enzymatic profile showed a significant increase in the percentage of glycolytic fibres in the pectoral muscle from chicken treated with a synbiotic with the addition of inulin (group SI).

Comparison of 2 commercial turkey hybrids: productivity, occurrence of breast myopathies, and meat quality properties.

This study was undertaken to compare productive performance, occurrence of breast myopathies, chemical composition, and technological properties of the meat in 2 dominant commercial turkey hybrids. A total of 972 1-day-old male turkey poults (equally divided in hybrid A and B) were randomly distributed in 18 floor pens. Overall, productive performance resulted similar between the genotypes, although they showed different growth profile (turkeys from group B grew up faster up to 84 d). Regarding the occurrence of myopathies, the percentage of breasts affected by white striping was markedly higher in both genotypes (46 vs. 60% of severe lesions, respectively for A and B; P < 0.05), while the occurrence of spaghetti meat-like condition was negligible. The histological features of the different categories of meat abnormalities resulted similar to those previously described for chicken hybrids. The technological traits such as ultimate pH, lightness, redness, marinade uptake, cooking losses, and shear force were not significantly affected by the genotype. However, turkeys from group B exhibited lower yellowness (b*, 0.50 vs. 1.04; P < 0.05) and higher drip losses (1.34 vs. 1.26%; P < 0.05). The shelf-life test on thigh meat showed no significant changes in meat color over the storage time in both hybrids, whereas thigh meat from group A showed absolute lower values of lightness (L*) and yellowness (b*) (P < 0.05). Lipid oxidation of thigh meat significantly increased during storage, although no significant difference was found between the hybrids. Proximate composition and intramuscular collagen properties resulted similar between genetic lines with the exception of total fat content (1.55 vs. 1.21%, respectively for A and B; P < 0.05). The genotype had a moderate effect on fatty acid families of breast meat as only monounsaturated fatty acid content was significantly affected (31.7 vs. 29.8%, respectively for A and B). In conclusion, the overall productive traits of commercial turkeys, including the occurrence of muscle myopathies, as well as quality attributes of fresh and refrigerated meat were only slightly affected by the genotype.

Effect of in ovo administration of different synbiotics on carcass and meat quality traits in broiler chickens.

The aim of this study was to examine the effect of in ovo synbiotic administration on slaughter performance and meat quality traits of broiler chickens. On day 12 of incubation, 5,850 eggs (Cobb 500 FF) were randomly divided into 3 experimental groups and automatically injected in ovo with physiological saline (control, C) and 2 different synbiotic formulations (SYN1: Lactobacillus salivarius + galactooligosaccharides; SYN2: Lactobacillus plantarum + raffinose family oligosaccharides). After hatching, 240 males were randomly chosen (80 chicks per group) and split into 8 replicate pens (10 birds per pen). At 42 d of age, 15 birds per treatment were weighed and slaughtered. In ovo synbiotic administration had a low effect on investigated traits, but depends on the kind of synbiotic administered. Both synbiotic formulations did not affect final BW, weight, and yield of carcass and pectoral muscle (PM); likewise, physicochemical properties (pH, color, water holding capacity), intramuscular collagen properties, and cholesterol content of PM were not affected by treatment. Synbiotic administration reduced (P = 0.061) the lipid content compared with C group, markedly (P < 0.05) with synbiotic SYN2. Meat from SYN1 birds displayed a higher (P < 0.01) content of saturated fatty acids (SFA), lower monounsaturated fatty acids (P < 0.05 compared only to SYN2), and lower (P < 0.01 and P < 0.05) polyunsaturated fatty acids (PUFA), n-6 PUFA and n-3 PUFA compared to C and SYN2 groups. The ratio of n-6 to n-3 PUFA was affected by the synbiotic administration (P = 0.039). Meat from C and SYN2 groups displayed a higher (P < 0.01) ratio of PUFA to SFA and lower (P < 0.01) atherogenic and thrombogenic indices compared to SYN1. In conclusion, this study has shown that in ovo administration of synbiotics did not negatively affect slaughter performance and physicochemical properties of meat. However, meat from C and SYN2 birds showed a preferable fatty acid profile, with a positive effect on nutritional properties of chicken meat.

Avian model to mitigate gut-derived immune response and oxidative stress during heat.

The tissue injury at the early stages of the heat stress response triggers release of inflammatory and oxidative agents from intestinal content into the milieu of the body. Intestinal homeostasis (i.e., eubiosis) improves the barrier function and mitigates the gut-derived influx of endotoxins. In this study we have analyzed the mitigating role of embryonic stimulation of the gut homeostasis in chickens on immune and oxidative responses to heat. The animal trial was conducted on broiler chickens. The treatment included a single in ovo injection of the galactooligosaccharides (GOS) prebiotic into the air cell of the egg on day 12 of incubation. Control eggs were in ovo injected with the same volume of sterile physiological saline. After hatching, birds were raised in group pens (6 pens/group, 25 birds/pen). Short-term, mild heat stress was induced on day 32 post-hatching by increase in the ambient temperature above the thermal comfort (30 °C for 8.5 h). The spleen was harvested from randomly selected individuals. The relative gene expression study was conducted with RT-qPCR. The two gene panels were analyzed: (1) immune response genes (IL-1ß, IL-2, IL-4, IL-6, IL-12p40 and IL-17) and (2) stress response genes (HSP25, HSP70, HSP90, BAG3, CAT and SOD). Data were evaluated by the analysis of variance in a 2 × 2 factorial design that included in ovo treatment and ambient temperature as factors. We have found that the immune-related and stress-related gene expression signatures were triggered in animals subjected to heat but with unbalanced intestinal flora (i.e., dysbiotic, without in ovo stimulation with GOS). These animals had increased expression of the genes involved in the immune responses (IL-4 and IL17) and stress responses (HSP25, HSP70, HSP90, CAT and SOD) to short-term heat stress that indicated presence of inflammatory and oxidative mediators (P < 0.05). The individuals that were in ovo stimulated with GOS did not mount the anti-inflammatory or antioxidative responses. Heat shock proteins (HSP25 and HSP70) were increased in both groups challenged with heat, which indicated their role in adaptation to heat.

Prebiotics offered to broiler chicken exert positive effect on meat quality traits irrespective of delivery route.

Elimination of antibiotic growth promoters from poultry production has encouraged intensive search for relevant alternatives. Prebiotics are proposed as efficient replacements to stimulate colonization/expansion of beneficial microflora in chickens. The aim of this study was to deepen the knowledge on the effect of prebiotic administration on slaughter performance and meat quality traits of broiler chickens by evaluating different routes of their delivery (in ovo vs. in-water vs. in ovo + in-water). At d 12 of incubation, 1,500 eggs (Ross 308) containing viable embryos were randomly allotted into 4 groups and injected in ovo with 0.2 mL solution containing: 3.5 mg/embryo BI (Bi2tos, trans-galactooligosaccharides); 0.88 mg/embryo DN (DiNovo, extract of Laminaria spp.); 1.9 mg/embryo RFO (raffinose family oligosaccharides) and 0.2 mL physiological saline (C). All prebiotics increased final BW compared to C group (P < 0.01), irrespective of delivery route. The prebiotics injected in ovo (T1) or in ovo combined with in-water supplementation (T2) increased carcass weight as compared with in-water group (T3), while T3 had the lowest carcass yield compared to the other groups. All prebiotics increased breast muscle weight and yield (P < 0.01), as well as fiber diameter (P < 0.05). Ultimate meat pH was lower (P < 0.01) in T3 than in T2 group. Meat from chickens treated with prebiotics showed a lower redness index, while lightness and yellowness were not affected by the treatments. Saturated fatty acid (SFA), polyunsaturated fatty acid (PUFA) and n-3 fatty acids contents were higher (P < 0.01), and monounsaturated fatty acid (MUFA) level was lower (P < 0.01) in prebiotic groups compared with C group. Nutritional indexes (n-6/n-3, PUFA/SFA ratio and thrombogenic index) displayed favorable human health-promoting values in the meat of chickens which were treated with prebiotics, irrespective of delivery route. Muscle cholesterol content was not affected by prebiotics. In conclusion, this study has shown that prebiotics can exert positive effects on growth of broiler chickens, carcass and meat quality traits, irrespective of delivery route.

Identification of quantitative trait loci affecting production and biochemical traits in a unique Japanese quail resource population.

The objective of the current study was to identify QTL associated with body weight, growth rate, egg quality traits, concentration of selected blood plasma, and yolk lipids as well as concentration of selected macro- and microelements, color, pH, basic chemical composition, and drip loss of breast muscle of Japanese quail (Coturnix japonica). Twenty-two meat-type males (line F33) were crossed with twenty-two laying-type females (line S22) to produce a generation of F1 hybrids. The F2 generation was created by mating 44 randomly chosen F1 hybrids, which were full siblings. The birds were individually weighed from the first to eighth week of age. At the age of 19 wk, 2 to 4 eggs were individually collected from each female and an analysis of the egg quality traits was performed. At slaughter, blood and breast muscles were collected from 324 individuals of the resource population. The basic chemical composition, concentration of chosen macro- and microelements, color, pH, and drip loss were determined in the muscle samples. The concentration of chosen lipids was determined in egg yolk and blood plasma. In total, 30 microsatellite markers located on chromosome 1 and 2 were genotyped. QTL mapping including additive and dominance genetic effects revealed 6 loci on chromosome 1 of the Japanese quail affecting the egg number, egg production rate, egg weight, specific gravity, egg shell weight, concentration of Na in breast muscle. In turn, there were 9 loci on chromosome 2 affecting the body weight in the first, fourth, and sixth week of age, growth rate in the second and seventh week of age, specific gravity, concentration of K and Cu in breast muscle, and the levels of triacylglycerols in blood plasma. In this study, QTL with a potential effect on the Na, K, and Cu content in breast muscles in poultry and on specific gravity in the Japanese quail were mapped for the first time.

Effect of different levels of dietary zinc, manganese, and copper from organic or inorganic sources on performance, bacterial chondronecrosis, intramuscular collagen characteristics, and occurrence of meat quality defects of broiler chickens.

The aim of the experiment was to assess the effects of 2 dietary levels of trace minerals (TM) zinc, manganese, and copper either from organic (OTM) or inorganic (ITM) sources on broiler performance, carcass traits, intramuscular collagen (IMC) properties, occurrence of hock burns (HB), foot pad dermatitis (FPD), femoral and tibia head necrosis, and breast muscle abnormalities (white striping, WS; wooden breast, WB; poor cohesion, PC). A total of 3,600 one-day-old male chicks were randomly assigned to one of 4 dietary treatments in a 2 × 2 factorial arrangement (9 replicates of 100 birds/dietary treatment). Birds were slaughtered at 31 (thinning) and 51 d of age. Body weight, daily weight gain (DWG), feed intake, feed conversion rate (FCR), and mortality were determined. A significant effect of the source of TM supplementation was found only in 51-day-old chickens. Birds of the OTM groups were heavier (P < 0.05), with a higher (P < 0.05) DWG and a better FCR (P < 0.05) compared with those of the ITM groups. OTM significantly reduced the lesion scores of femoral head (P = 0.004) and total leg (femur + tibia, P = 0.02) compared to ITM, which is mainly caused by the reduction of the percentages of femoral head transitional degeneration (FHT, P = 0.04) and femoral head necrosis (FHN, P = 0.07). Carcass traits were similar among the experimental groups. No alleviating effect of TM administration on the incidence of FPD and HB in 31- and 51-day-old chickens was found. Similarly, the occurrence and the degrees of WS and WB in 51-day-old chickens was affected neither by the doses nor by the source of TM supplied. IMC characteristics of broiler pectoral muscle were not affected (P > 0.05) by the different sources and doses of TM administrated.

Influence of different prebiotics and mode of their administration on broiler chicken performance.

In the post-antibiotics era, prebiotics are proposed as alternatives to antibiotic growth promoters in poultry production. The goal of this study was to compare in ovo method of prebiotic delivery with in-water supplementation and with both methods combined (in ovo+in-water) in broiler chickens. Two trials were conducted. Trial 1 was carried out to optimize the doses of two prebiotics, DN (DiNovo®, extract of beta-glucans) and BI (Bi2tos, trans-galactooligosaccharides), for in ovo delivery. The estimated parameters were hatchability and bacteriological status of the newly hatched chicks. Prebiotics were dissolved in 0.2 ml of physiological saline, at the doses: 0.18, 0.88, 3.5 and 7.0 mg/embryo; control group (C) was injected in ovo with 0.2 ml of physiological saline. Trial 2 was conducted to evaluate effects of different prebiotics (DN, BI and raffinose family oligosaccharides (RFO)) delivered in ovo, in-water and in a combined way (in ovo+in-water) on broiler chickens performance. The results of the Trial 1 indicated that the optimal dose of DN and BI prebiotics delivered in ovo, that did not reduce chicks' hatchability, was 0.88 mg/embryo (DN) and 3.5 mg/embryo (BI). Both prebiotics numerically increased number of lactobacilli and bifidobacteria in chicken feces (P>0.05). In Trial 2, all prebiotics (DN, BI and RFO) significantly increased BW gain compared with the C group (P<0.05), especially during the first 21 days of life. However, feed intake and feed conversion ratio were increased upon prebiotics delivery irrespective of method used. Injection of prebiotics in ovo combined with in-water supplementation did not express synergistic effects on broilers performance compared with in ovo injection only. Taken together, those results confirm that single in ovo prebiotics injection into the chicken embryo can successfully replace prolonged in-water supplementation post hatching.

Effect of intramuscular injections of DL-α-tocopheryl acetate on growth performance and extracellular matrix of growing lambs.

The effect of intramuscular injections of vitamin E on growth, carcass traits, intramuscular collagen (IMC) characteristics and decorin of growing lambs was studied. A total of 24 15-day-old Ile de France suckling male lambs were divided into two groups and weekly intramuscular injections of DL-α-tocopheryl acetate (control group, 0 IU; Vitamin E treatment, 150 IU) were given until the lambs were 64 days old. Lambs were individually weighted at 15, 29, 43, 57 days of age and at slaughter (71 days old). Dry matter intake and average daily weight gain were recorded. Hot and cold carcass weights were recorded and dressing percentages were calculated after dressing and chilling (2°C to 4°C for 24 h). Carcass shrink losses were calculated as well. Longissimus muscle (LM) pH and area were measured. The pelvic limb was removed and its percentage was calculated based on cold carcass weight. IMC and decorin analyses were assessed on LM and semimembranosus muscle (SM). DL-α-tocopheryl acetate treatment reduced (P<0.05) collagen maturity and increased (P<0.05) decorin in both LM and SM muscles of growing lambs, while it did not affect IMC content. In addition, vitamin E did not influence growth, carcass weight, dressing percentage, carcass shrink losses and area of LM but decreased (P<0.05) the pelvic limb percentage. The LM pH values were higher (P<0.05) in vitamin group than in control group. Furthermore, different IMC characteristics between the muscles (P<0.01) were apparent. Multiple intramuscular injections of DL-α-tocopheryl acetate influence extracellular matrix in lambs, which could affect meat tenderness.

Growth performance, meat quality traits, and genetic mapping of quantitative trait loci in 3 generations of Japanese quail populations (Coturnix japonica).

The current research was conducted to compare growth, carcass traits, pH, intramuscular collagen (IMC) properties, and genetic bases of IMC and carcasses (breast-muscle weight) of different lines and generations of adult males and females of Japanese quail (Coturnix japonica). Forty-four quails (generation F0), 22 Pharaoh (F-33) meat-type males and 22 Standard (S-22) laying-type females, were crossed to produce the F1 hybrids generation. The F2 generation was created by mating one F1 male with one F1 female, full siblings. The birds, randomly chosen from F0 (22 males and 22 females), F1 (22 males and 22 females), and F2 (84 males and 152 females) were raised to 20 wk of age in collective cages. Quails were fed ad libitum commercial diets. At slaughter, all birds were individually weighed (after a fasting period of 12 h) and dressing yield (without giblets) was calculated. The carcasses were then dissected. Genomic DNA was extracted from all of the blood, and 30 microsatellite markers located on 2 quail chromosomes were genotyped. The F -: 33 quails had higher in vivo and postmortem performances and a higher abdominal fat percentage than those of the egg line. Meat from S -: 22 quails had a slower collagen maturation (hydroxylysylpyridinoline crosslink/collagen) and a higher ultimate pH. The F1 and F2 generations showed an evident sexual dimorphism, and an additional effect could be due to hybrid heterosis evident in F2. Meat from quails of F1 and F2 generations had a lower IMC amount with a higher degree of collagen maturation compared with parental lines. Two statistically significant QTL have been detected on quail chromosome 2 (CJA02): a QTL with an additive effect (0.50) for IMC in the marker bracket GUJ0037 and GUJ0093; a second QTL with additive (1.32) and dominant (1.91) effects for breast-muscle weight in the marker bracket GUJ0084 and GUJ0073. To our knowledge, this is the first report of a QTL associated with breast-muscle weight and IMC in quail and poultry species, respectively.

Influence of in ovo prebiotic and synbiotic administration on meat quality of broiler chickens.

A trial was conducted to evaluate the effect of in ovo injection of prebiotic and synbiotics on growth performance, meat quality traits (cholesterol content, intramuscular collagen properties, fiber measurements), and the presence of histopathological changes in the pectoral muscle (PS) of broiler chickens. On d 12 of incubation, 480 eggs were randomly divided into 5 experimental groups treated with different bioactives, in ovo injected: C, control with physiological saline; T1 with 1.9 mg of raffinose family oligosaccharides; T2 and T3 with 1.9 mg of raffinose family oligosaccharides enriched with different probiotic bacteria, specifically 1,000 cfu of Lactococcus lactis ssp. lactis SL1 and Lactococcus lactis ssp. cremoris IBB SC1, respectively; T4 with commercially available synbiotic Duolac, containing 500 cfu of both Lactobacillus acidophilus and Streptococcus faecium with the addition of lactose (0.001 mg/embryo). Among the hatched chickens, 60 males were randomly chosen (12 birds for each group) and were grown to 42 d in collective cages (n = 3 birds in each 4 cages: replications for experimental groups). Broilers were fed ad libitum commercial diets according to age. In ovo prebiotic and synbiotic administration had a low effect on investigated traits, but depend on the kind of bioactives administered. Commercial synbiotic treatment (T4) reduced carcass yield percentage, and the feed conversion ratio was higher in T3 and T4 groups compared with other groups. The abdominal fat, the ultimate pH, and cholesterol of the PS were not affected by treatment. Broiler chickens of the treated groups with both slightly greater PS and fiber diameter had a significantly lower amount of collagen. The greater thickness of muscle fibers (not significant) and the lower fiber density (statistically significant), observed in treated birds in comparison with those of the C group, are not associated with histopathological changes in the PS of broilers. The incidence of histopathological changes in broiler chickens from examined groups was low, which did not affect the deterioration of meat quality obtained from these birds.