Effects of physical forms of a high grain-based diet on fattening performance, ruminal health, feeding behaviour, nutrient digestibility and carcass traits of finishing Lohi lambs.

This study aimed to evaluate the influence of different physical forms of complete diets on performance, feeding behaviour, digestibility, ruminal health, blood and carcass indices in fattening lambs. A randomised complete block design was used to assign thirty male Lohi lambs (300 ± 15 d old) with an initial body weight of 33 ± 1.4 kg in ten replications to one of three physical forms of the diet. For different treatments, the dietary ingredients were ground and mixed as (I) ground conventional mash (CM), (II) whole corn grains were mixed with the remaining pelleted ingredients as a texturised diet (TX), and (III) whole corn grains and the remaining ingredients were mixed as an unprocessed diet (UP). During the 60-d growth trial and 7-d digestibility experiment, individually housed lambs were fed ad libitum. Feeding diet UP improved (p < 0.05) dry matter intake, average daily gain and feed-to-gain ratio of fattening lambs. The ruminal pH tended to be lower in group TX compared with the other groups. The incidence of loose faeces consistency was 3.5 times higher (p < 0.05) in group TX compared to group UP. The daily intakes of dry matter (DM) and neutral detergent fibre (NDF), the rumination time and chewing activities were highest (p < 0.05) for lambs fed on the UP diet. The digestibility of DM, NDF and ether extract were greater (p < 0.05) for diet UP as compared to diet TX. The chilled and hot carcass weights were highest (p < 0.05) for group UP. The papillae density tended to be greater for group UP. However, blood metabolites, intestinal morphology, carcass marbling, tenderness, meat pH, cooking loss, and meat composition were similar across the treatments. It can be concluded that the unprocessed diet based on whole corn grain and soybean hulls improved growth performance, feeding behaviour and carcass yield through better nutrient utilisation and a stable ruminal environment.

Effects of gender and slaughter age on meat quality of Anatolian water buffaloes.

The study aimed to investigate the effects of slaughter age and gender on specific carcass and technological meat quality characteristics in Anatolian water buffaloes. The study was conducted on 55 water buffaloes using a 2 × 2 factorial design with two independent variables at two levels. Gender subgroups of male (n = 29) and female (n = 26) and slaughter age subgroups of younger than 2 years of age (n = 29) and older than 2 years of age (n = 26) were evaluated. Hot carcass and cold carcass weights were higher in old water buffaloes than young ones (P < 0.001). The skin weight of old buffaloes was also higher than young buffaloes (P < 0.01). Drip loss, expressed juice, and Warner Bratzler (WB) shear force values of longissimus dorsi (LD) muscles were not influenced by age group and gender of buffaloes. The lightness (L*) and hue (H*) values were higher in young buffaloes than old animals (P < 0.001). The meat of male buffaloes had lower redness (a*) and chroma (C*) values than that of female buffaloes. The current results indicated that female water buffalo could also be used for meat production away from negative impressions on the meat quality of female water buffalo.

Effects of dietary arginine supplementation on muscle structure, meat characteristics and lipid oxidation products in lambs and its potential mechanisms of action.

This study aimed to assess the effect of dietary arginine supplementation on muscle structure and meat characteristics of lambs also considering lipid oxidation products and to contribute to reveal its mechanisms of action using tandem mass tagging (TMT) proteomics. Eighteen lambs were allocated to two dietary treatment groups: control diet or control diet with the addition of 1% L-arginine. The results revealed that dietary arginine supplementation increased muscle fibre diameter and cross-sectional area (P < 0.05), which was attributable to protein deposition, as evidenced by increased RNA content, RNA/DNA ratio, inhibition of apoptotic enzyme activity, and alterations in the IGF-1/Akt signaling pathway (P < 0.05). In addition, dietary arginine elevated pH24h, a* values, and IMF content, decreased shear force value and backfat thickness (P < 0.05), as well as decreased the formation of lipid oxidation products involved in meat flavor including hexanal, heptanal, octanal, nonanal and 1-octen-3-ol by increasing the antioxidant capacity of the muscle (P < 0.05). The proteomics results suggested that seven enrichment pathways may be potential mechanisms by which arginine affected the muscle structure and meat characteristics of lambs. In summary, arginine supplementation in lamb diets provides a safe and effective way to improve meat quality, and antioxidant capacity of muscle of lamb.

Effect of precursor amino acids for carnosine synthesis on breast fiber microstructures and myofiber differentiation-related gene expression in slow-growing chicken.

OBJECTIVE: The effects of carnosine synthesis on the structural and microstructural determinants of meat quality have not been studied to date. Therefore, this study aimed to investigate the effect of supplementation with carnosine synthesis precursors on the characteristics and microstructure of breast muscle fibers in slow-growing Korat chickens (KR). METHODS: Slow-growing KR were fed a non-supplemented commercial diet (control group) or a commercial diet supplemented with 1.0% ß-alanine, 0.5% L-histidine, or a combination of both 1.0% ß-alanine and 0.5% L-histidine. At 10 weeks, KR were slaughtered, and the breast muscle was collected. Samples were fixed and extracted to study the microstructure, fat level, and porosity of the meat using X-ray and scanning electron microscopy, and real-time polymerase chain reaction was performed to analyze the expression of genes related to myofiber differentiation. RESULTS: L-histidine supplementation significantly altered myofiber diameter and muscle fiber density and compactness by regulating muscle fiber-type differentiation via carnosine synthase (CARNS1) and myocyte enhancer factor 2C expression, as well as myogenic differentiation antigen and myogenic regulatory factor 5 expression. While excess L-histidine potentially stimulated CARNS1 to modify muscle fiber arrangement and tenderness in breast meat, dietary ß-alanine supplementation alone or in combination with L-histidine supplementation induced a relatively less remarkable but not significant (p<0.05) effect on the breast meat characteristics studied. CONCLUSION: Interestingly, the combination of ß-alanine and L-histidine supplementation had no effect on meat microstructure, meat porosity, and fat content in comparison with the control group. Thus, this combination had the best selectivity for improving meat quality. However, further studies are required to clarify the effects of carnosine levels on meat processing.

Bioaccessibility of condensed tannins and their effect on the physico-chemical characteristics of lamb meat.

The bioaccessibility of tannins as antioxidants in meat is essential to maximise their effectiveness in protecting the product. This property determines the amount of tannins available to interact with meat components, inhibiting lipid and protein oxidation and, consequently, prolonging shelf life and preserving the sensory quality of the product. The objective of this study was to evaluate the bioaccessibility of condensed tannins (CT) from Acacia mearnsii extract (AME) and their effect on the physico-chemical characteristics of fattened lamb meat. Thirty-six Dorset × Hampshire lambs (3 months old and 20.8 ± 3.3 kg live weight) were used. The lambs were distributed equally (n = 9) into four treatments: T1, T2, T3 and T4, which included a basal diet plus 0%, 0.25%, 0.5% and 0.75% of CT from AME, respectively. At the end of the fattening period, bioaccessibility was evaluated, the animals were slaughtered and a sample of the longissimus dorsi (LD) muscle was collected to assess colour, lipid oxidation, cooking weight loss and shear force on days 1, 4, 7 and 14 of shelf-life, in samples preserved at -20 °C. In addition, the long chain fatty acid profile was analysed. A completely randomised design was used, and the means were compared with Tukey's test (P < 0.05). The mean lightness (L*), yellowness (b*) and hue (H*) values were higher for T3 and T4. The addition of CT did not affect (P > 0.05) redness (a*), cooking weight loss (CWL) or shear force (SF). T4 decreased (P < 0.05) stearic acid and increased cis-9 trans-12 conjugated linoleic acid (CLA). Bioaccessibility was higher in the supplemented groups (T1 < T2, T3 and T4). In conclusion, supplementing CT from AME in the diet of lambs did not reduce lipid oxidation, but T3 or T4 improved some aspects of meat colour and CLA deposition.

Feeding Behavior, Growth Performance and Meat Quality Profile in Broiler Chickens Fed Multiple Levels of Xylooligosaccharides.

A total of 240 1-day-old Arbor Acres broiler chickens were randomly distributed to 4 treatment groups with 6 replicates and 10 birds per replicate. Chickens were fed with corn-soybean meal diet supplementation with additions of 0, 150, 300, and 450 mg/kg XOS for 42 days. At 4 weeks of age, the average feeding time was reduced in the 450 mg/kg XOS group (p < 0.05), and the percentage of feeding time was increased in the 300 mg/kg XOS group (p < 0.05). At 5 weeks of age, broilers fed with 300 mg/kg XOS had increased the percentage of feeding time (p < 0.05), and 450 mg/kg XOS had increased the feeding frequency and percentage of feeding time (p < 0.05). At 6 weeks of age, the feeding frequency was highest in the 450 mg/kg XOS group (p < 0.05). During 4 to 6 weeks of age, the average feeding time was increased in 300 mg/kg XOS group (p < 0.05), the frequency was improved in the 450 mg/kg XOS group (p < 0.05), and the percentage of feeding time was longer in the XOS group than that in the control group (p < 0.05). The average daily gain was improved during days 22-42 and days 1-42 in the 150 mg/kg XOS group (p < 0.05). Broilers fed with 300 mg/kg XOS had an increased eviscerated rate (p < 0.05). The pH45min of breast muscle was highest in the 450 mg/kg XOS group (p < 0.05), as well as the pH45min and pH24h of thigh muscle, which improved in the 300 mg/kg and 450 mg/kg XOS groups (p < 0.05). In addition, the cooking loss of thigh muscle was reduced in the 300 mg/kg XOS group (p < 0.05). In conclusion, dietary supplementation with XOS had positive effects on the feeding behavior, growth performance, and meat quality of broiler chickens.

Thigh muscle metabolic response is linked to feed efficiency and meat characteristics in slow-growing chicken.

The Korat chicken (KR) is a slow-growing Thai chicken breed with relatively poor feed efficiency (FE) but very tasty meat with high protein and low fat contents, and a unique texture. To enhance the competitiveness of KR, its FE should be improved. However, selecting for FE has an unknown effect on meat characteristics. Thus, understanding the genetic basis underlying FE traits and meat characteristics is needed. In this study, 75 male KR birds were raised up to 10 wk of age. For each bird, the feed conversion ratio (FCR), residual feed intake (RFI), and physicochemical properties, flavor precursors, and biological compounds in the thigh meat were evaluated. At 10 wk of age, thigh muscle samples from 6 birds (3 with high FCR and 3 with low FCR values) were selected, and their proteomes were investigated using a label-free proteomic method. Weighted gene coexpression network analysis (WGCNA) was used to screen the key protein modules and pathways. The WGCNA results revealed that FE and meat characteristics significantly correlated with the same protein module. However, the correlation was unfavorable; improving FE may result in a decrease in meat quality through the alteration in biological processes including glycolysis/gluconeogenesis, metabolic pathway, carbon metabolism, biosynthesis of amino acids, pyruvate metabolism, and protein processing in the endoplasmic reticulum. The hub proteins of the significant module (TNNT1, TNNT3, TNNI2, TNNC2, MYLPF, MYH10, GADPH, PGK1, LDHA, and GPI) were also identified to be associated with energy metabolism, and muscle growth and development. Given that the same proteins and pathways are present in FE and meat characteristics but in opposite directions, selection practices for KR should simultaneously consider both trait groups to maintain the high meat quality of KR while improving FE.

Dietary Coleus amboinicus Lour. decreases ruminal methanogenesis and biohydrogenation, and improves meat quality and fatty acid composition in longissimus thoracis muscle of lambs.

BACKGROUND: Methane production and fatty acids (FA) biohydrogenation in the rumen are two main constraints in ruminant production causing environmental burden and reducing food product quality. Rumen functions can be modulated by the biologically active compounds (BACs) of plant origins as shown in several studies e.g. reduction in methane emission, modulation of FA composition with positive impact on the ruminant products. Coleus amboinicus Lour. (CAL) contains high concentration of polyphenols that may potentially reduce methane production and modulate ruminal biohydrogenation of unsaturated FA. This study aimed to investigate the effect of BAC of Coleus amboinicus Lour. (CAL) fed to growing lambs on ruminal methane production, biohydrogenation of unsaturated FA and meat characteristics. In this study, the in vitro experiment aiming at determining the most effective CAL dose for in vivo experiments was followed by two in vivo experiments in rumen-cannulated rams and growing lambs. Experiment 1 (RUSITEC) comprised of control and three experimental diets differing in CAL content (10%, 15%, and 20% of the total diet). The two in vivo experiments were conducted on six growing, rumen-cannulated lambs (Exp. 2) and 16 growing lambs (Exp. 3). Animals were assigned into the control (CON) and experimental (20% of CAL) groups. Several parameters were examined in vitro (pH, ammonia and VFA concentrations, protozoa, methanogens and select bacteria populations) and in vivo (methane production, digestibility, ruminal microorganism populations, meat quality, fatty acids profiles in rumen fluid and meat, transcript expression of 5 genes in meat). RESULTS: CAL lowered in vitro methane production by 51%. In the in vivo Exp. 3, CAL decreased methane production by 20% compared with the CON group, which corresponded to reduction of total methanogen counts by up to 28% in all experiments, notably Methanobacteriales. In Exp. 3, CAL increased or tended to increase populations of some rumen bacteria (Ruminococcus albus, Megasphaera elsdenii, Butyrivibrio proteoclasticus, and Butyrivibrio fibrisolvens). Dietary CAL suppressed the Holotricha population, but increased or tended to increase Entodiniomorpha population in vivo. An increase in the polyunsaturated fatty acid (PUFA) proportion in the rumen of lambs was noted in response to the CAL diet, which was mainly attributable to the increase in C18:3 cis-9 cis-12 cis-15 (LNA) proportion. CAL reduced the mRNA expression of four out of five genes investigated in meat (fatty acid synthase, stearoyl-CoA desaturase, lipoprotein lipase, and fatty acid desaturase 1). CONCLUSIONS: Summarizing, polyphenols of CAL origin (20% in diet) mitigated ruminal methane production by inhibiting the methanogen communities. CAL supplementation also improved ruminal environment by modulating ruminal bacteria involved in fermentation and biohydrogenation of FA. Besides, CAL elevated the LNA concentration, which improved meat quality through increased deposition of n-3 PUFA.

Germinated papaya seed alone or in combination with chitosan on growth, health and meat quality of broilers during grower period.

The study investigated the effect of a mixture of germinated papaya seed flour and chitosan (GPS-CH) in comparison to the germinated papaya seed flour (GPS) alone on growth, blood profile, intestinal indices and meat quality of broilers. A total of 288 14-day old Cobb chicks were divided into three groups with 8 replications, including CONT (chicks receiving basal feed with no additive), GPS (chicks receiving basal feed supplemented with 0.5% GPS), and GPS-CH (chicks receiving basal feed supplemented with 0.5% GPS and 0.2% chitosan). Treatments had no effect (p > 0.05) on broiler growth. Spleen was lower (p < 0.05) in GPS and GPS-CH than in CONT. Thrombocytes were lower (p < 0.05) in GPS and GPS-CH than in CONT. Total triglyceride and protein were higher (p < 0.05) in GPS and GPS-CH than in CONT. Jejunal villi height (VH) and ileal VH to crypt depth ratio of GPS-CH were higher (p < 0.05) than that of CONT and GPS birds. Total fat in breast meat was lower (p < 0.05) in GPS-CH than in CONT and GPS. The highest (p < 0.05) pH was found in GPS-CH breast. The yellowness values were lower (p < 0.05) in GPS-CH than in CONT and GPS breast. GPS thigh had lowest (p < 0.05) moisture and highest (p < 0.05) fat. Ash was higher (p < 0.05) in GPS-CH than in CONT thigh. Water holding capacity (WHC) was higher (p < 0.05) in GPS-CH than in CONT and GPS thigh meats. Cooking loss was lower (p < 0.05) in GPS-CH than in GPS thigh meats. Compared to GPS, the pH values of thigh meats were higher (p < 0.05) in GPS-CH and CONT meats. The yellowness values were lower in GPS and GPS-CH than in CONT thigh. In conclusion, GPS-CH was beneficial in improving immune responses, nutrient bioavailability, intestinal morphology and meat quality of broilers during the grower period.

Carcass Traits, Meat Quality, and Volatile Compounds of Lamb Meat from Different Restricted Grazing Time and Indoor Supplementary Feeding Systems.

This study was conducted to investigate the carcass traits, meat quality, and volatile compounds of growing lambs under different restricted grazing time and indoor supplementary feeding systems. Fifty 3-month-old male Tan lambs (with similar body weight) were divided into five groups randomly according to grazing time 12 h/d (G12), 8 h/d(G8), 4 h/d(G4), 2 h/d (G2), and 0 h (G0, indoor supplementary feeding). Animals were slaughtered at the end of the experiment, and the longissimus thoracis (LT) samples were collected for further analysis. The results indicated that indoor supplementary feeding improved the percentages of carcass fat and non-carcass fat of pre-slaughter weight (PSW) and decreased the cooking loss of lamb meat. Grazing for 8 h/d or 2 h/d enhanced PSW, carcass, and meat percentages of PSW. Lambs grazing for 2 h/d with supplement and indoor supplementary feeding lambs had a higher level of intramuscular fat and lightness (L*) value and lower cooking loss in the LT muscle, but higher yellowness (b*) and fat content were found in indoor supplementary feeding lambs. More categories of volatile compounds were identified in meat from grazing lambs than from indoor supplementary feeding lambs, but lower content of aldehydes and total volatile flavor compounds was detected in grazing lambs. Overall, the results demonstrated that the feeding system is a main factor that affects lamb meat quality, and proper grazing time can improve the quantity and quality of lamb meat and provide meat with different flavors to the consumers.

Effects of vitamin A on carcass and meat quality of broilers.

This study evaluated the level and length of time of vitamin A supplementation and its effects on carcass and cuts yield, meat quality, and myopathies in 42-day-old broilers. A total of 1,920 birds were divided into 6 groups, and each group received a different level of vitamin A: 0; 6,000; 16,000; 26,000; 36,000 and 46,000 IU/ kg. From d 1 to 21, the treatments were distributed among 16 replicates with 20 birds. From the 22nd d on, 8 repetitions remained with the initial treatment and the others received diets with no vitamin A supplementation. Twelve birds were slaughtered per treatment to evaluate carcass and cuts yield, shear force, cooking loss, water holding capacity, and the presence of substances reactive to thiobarbituric acid. The remaining birds were slaughtered and evaluated in loco for Wooden Breast (WB) and White Striping (WS). Wings weight was affected by vitamin A levels. The duration of the vitamin A supplementation process had effects on the weight of breast, legs with a dorsal portion, and meat color in the yellow intensity (b*). Incidence of WB had higher scores in birds supplemented until 42 d of age. WS showed a quadratic response and a lower response with supplementation of 29,700 IU/ kg. Even for WS, a higher occurrence of the normal score was found in birds supplemented until 21 d of age. Minimal quadratic responses were obtained for normal, moderate, and severe scores, in supplementations of 29,301; 29,959, and 29,827 IU/ kg, respectively. WB had lower occurrence rates in birds supplemented until 21 d of age. Consequently, the severe score was more frequent when supplementation was provided until 42 d of age. The level of vitamin A and the length of time during which this supplementation was provided had influence on cuts yield, meat color and the incidence of WB and WS of the 42-day-old birds.

Effects of Decabrominated Diphenyl Ether Exposure on Growth, Meat Characteristics and Blood Profiles in Broilers.

Decabrominated diphenyl ether (BDE-209) is widely used as a flame retardant and is detected at high levels in the environment. Its toxicities have been reported and have attracted attention. In the present study, broilers were used to determine the response in growth performance, carcass traits, meat quality, blood profiles and antioxidant system to BDE-209 exposure at doses of 0, 0.02, 0.4 and 4 mg/kg. The results showed that BDE-209 exposure at levels of 0.02 or 0.4 mg/kg increased feed intake and decreased feed efficiency. BDE-209 altered the blood profiles, such as reducing the numbers of white blood cells, lymphocytes and neutrophilic granulocytes. As compared with the control, BDE-209 exposure significantly increased abdominal fat percentages of broilers at 64.9-159.5% and adversely affected the selected biochemical indicators, including alkaline phosphatase (ALP), aspartate aminotransferase (AST), alanine aminotransferase (ALT), creatine (CRE), which indicated its toxicity to liver and kidney functions. Moreover, BDE-209 exposure significantly increased plasma malondialdehyde (MDA) concentrations and decreased the activities of glutathione peroxidase (GSH-px) and superoxide dismutase (SOD), which implied aggravating oxidant stress and decline of antioxidant capacity in broilers. In conclusion, our data demonstrated that the environmental pollutant BDE-209 adversely influenced growth performance, increased the deposition of abdominal fat, impaired antioxidant capacity and the immune system and had potential toxicity to the liver and kidney of broilers.

The Effects of Using Pineapple Stem Starch as an Alternative Starch Source and Ageing Period on Meat Quality, Texture Profile, Ribonucleotide Content, and Fatty Acid Composition of Longissimus Thoracis of Fattening Dairy Steers.

The effects of different starch sources (ground corn (CO), ground cassava (CA) and pineapple stem starch (PI)) and ageing period (14 and 21 days) on meat characteristics of Holstein steers were investigated. Starch sources had no effect on meat characteristics, while meat aged for 14 days had less thawing loss than that aged for 21 days. Meat from steers fed PI had higher levels of inosine monophosphate (IMP) than the others (p < 0.05). With increasing duration of ageing, the content of IMP and guanosine monophosphate in the meat decreased, while the content of hypoxanthine increased (p < 0.05). Meat from steers fed CO had the highest oleic acid but the lowest erucic acid (p < 0.05) in contrast to meat from steers fed PI, which had the lowest oleic acid but the highest erucic acid. Steers fed CO appeared to produce healthier meat as this was positively associated with monounsaturated fatty acid content. Meat from steers fed PI had higher levels of IMP, which may be associated with good taste.

The effect of immunization against gonadotropin-releasing factor in market gilts: Meta-analyses of parameters relevant for pig producers, pork packers and retailers/consumers.

The vaccine against gonadotropin releasing factor (GnRF), Improvac®, has recently emerged as an option for rearing market gilts up to heavier harvest weights. Improvac's® temporary suppression of the ovarian function and gonadal hormones results in greater feed intake and better welfare from avoidance of sexual behavioral problems. Based on 22 published articles, our meta-analysis has quantified the effect of immunizing gilts against GnRF on parameters relevant for pig producers, pork packers and retailers/consumers. The meta-analyses included growth performance and final harvest parameters, general carcass traits and yield of valuable meat, meat and fat quality parameters. Primary analyses considered studies without ractopamine, subgroup and additional analyses assessed the impact of co-variates. From the perspective of pig producers, primary analyses showed that immunized (IM) gilts have significantly (P < 0.001) increased average daily gain (+45.1 g/day) and daily feed intake (+0.19 kg/day), higher final live weight (+4.0 kg) and more backfat (+2.8 mm). From the perspective of the pork packers, IM gilts have heavier carcasses (+3.2 kg; P < 0.001), whereas dressing percentage is similar. IM gilts are less lean (-1.5% units; P < 0.001) and have 0.21% units more intramuscular fat (P = 0.001). The yield of ham, shoulder, and loin is similar, whereas the yield of belly is significantly higher (+0.28 kg; P < 0.001). There are no differences in meat quality parameters (color, pH24, and drip loss) between IM gilts and untreated gilts, whereas a lower iodine value in IM gilts indicates an improved fat quality. Further subgroup and additional analyses confirmed the validity of our meta-analysis.

Growth Performance and Meat Characteristics of the First Awassi-Rambouillet Callipyge Backcross.

The Awassi breed is desirable due to its resilient traits, but shows poor lean meat content on the carcass; the callipyge mutation may enhance growth and meat characteristics. The first backcross of callipyge Awassi-Rambouillet (CRAW) lambs was generated by mating Awassi ewes with heterozygous F1 (50 % Awassi and 50 % Rambouillet) rams for the callipyge mutation. A fattening trial with carriers of CLPG (CRAW), non-carriers (RAW), and Awassi (AW) ram lambs was conducted for 94 days and growth and meat characteristic parameters were recorded. Final body weight, average daily gain (ADG), feed conversion ratio, and dry matter intake, but not initial body weight, were greater in CRAW and RAW lambs as compared to AW lambs; hot and cold carcass, dressing percentage, and shoulder, rack, and loin weights were greater in CRAW vs. AW but not RAW lambs. Leg cuts were heavier in CRAW vs. both RAW and AW lambs; intermuscular and subcutaneous fat percentages were greater in CRAW as compared to AW but not RAW lambs. Non-carcass components showed kidney fat, kidney, liver and testes weights higher in CRAW lambs as compared to AW lambs, but these parameters were similar to those of RAW lambs. There were no differences in fat tail weight. Further, CRAW lambs had higher shear force and water holding capacity than RAW and AW lambs, while cooking loss was the lowest in CRAW lambs. In conclusion, the callipyge mutation with 25% Rambouillet genes can provide efficient improvements in growth and meat characteristics, with the exception of tenderness in Awassi sheep.

Growth Performance, Body Measurements, Carcass and Some Internal Organs Characteristics of Pekin Ducks.

Native breeds of ducks have been the subject of many studies in the past, yet the relevant knowledge is still incomplete and needs to be further expanded. The objective of this study was to provide information about differences in growth performance, dressing percentage, carcass composition and digestive morphometry among three lines of Pekin ducks from conservation flocks raised in Poland. The study used 180 sexed Pekin ducks-30 males and 30 females of line P33 (ducks of Polish origin), 30 males and 30 females of line P8 (ducks of Danish origin), and 30 males and 30 females of line P9 (ducks of French origin). Throughout the study (49 d), ducks were confined indoors in six pens. Birds were fed complete commercial diets ad libitum and had unrestricted access to water. The compared lines of ducks differed significantly in body weight from 1 to 49 d of age except of ducks of both sexes at 14 d. At 49 d of age, significant differences were observed between the tested ducks in all the body measurements. Duck genotype had a significant effect on preslaughter body weight, carcass weight and breast muscle, neck and remainders contents, caeca length, liver weight and gizzard percentage. The results show that the tested ducks were significantly different and unique, mainly in terms of the body biometric characteristics.

Comprehensive evaluation of growth performance and meat characteristics of a fattening system combining grazing with feeding rice whole-crop silage in Japanese Black steers.

We investigated the effect of a system for fattening steers combining grazing with feeding rice whole-crop silage (rWCS) on growth performance, meat characteristics, and the expression of genes involved in skeletal muscle growth. Steers were randomly assigned to grazing or concentrate-fed groups (CT). The grazing group (GZ) was fed rWCS after grazing until 16 months of age. The final body weight was the same in the two groups, but the dressed weight was lower in the GZ than in the CT. The beef color standard was higher in the GZ than in the CT. Although beef marbling did not differ between the two groups, there was less intramuscular fat and subcutaneous fat in the GZ than in the CT. The α-tocopherol and ß-carotene contents in the muscle were higher in the GZ than in the CT. The GZ showed a lower daily gain (DG) during the grazing period, which may have resulted from decelerating skeletal muscle growth caused by the increased expression of genes encoding myostatin and atrogin-1. However, the DG and feed efficiency of the GZ increased after grazing. The two groups exhibited a similar level of beef productivity.

Influence of feeding a grass hay diet during the early stage of the fattening period on growth performance, carcass characteristics, and meat production in Japanese Black steers.

The present study investigated the influence of feeding a large amount of grass hay to steers from the early to middle fattening period on growth, carcass characteristics, and meat characteristics. Steers were randomly divided into grass hay-fed (GHF, n = 6) and concentrate-fed (CF, n = 6) groups. The dressed weight of the GHF steers was lower than that of the CF steers, but the final body weight was not significantly different between the groups. The GHF steers had decreased subcutaneous fat and rib thickness compared with the CF steers. Lipid content, monounsaturated fatty acids, and drip loss in the muscles were lower in the GHF steers than in the CF steers. Furthermore, n-3 polyunsaturated fatty acids were higher in the GHF steers compared with the CF steers. The GHF steers had lower body weight during the middle fattening stage, which may have occurred as a result of muscle growth suppression caused by increased Myostatin expression; an increase in daily gain during the finishing period may have occurred as a result of muscle growth activation caused by decreased Myostatin expression. Feeding steers a grass hay-based diet during the early fattening period possibly maintains the quantitative productivity of beef similarly to feeding a concentrate-based diet.

Thyme oil inclusion levels in a rabbit ration: Evaluation of productive performance, carcass criteria and meat quality under hot environmental conditions.

The aim of this study was to determine the impact of thyme essential oil supplementation in rabbit rations on performance, carcass criteria, and meat quality under hot environmental conditions. A total of 75, 4-week-old Californian male rabbits were assigned to 5 dietary treatments until 12 weeks of age. The rabbits were reared in an open house system (38 °C average ambient temperature and 26% to 35% relative humidity). Treatments were as follows: unsupplemented standard ration, negative control (CON); standard ration supplemented with 1.50 g/kg olive oil as carrier, positive control (POS); POS + 50 mg/kg thyme oil (TO1); POS + 100 mg/kg thyme oil (TO2); and POS + 150 mg/kg thyme oil (TO3). Dietary thyme oil up to 150 mg/kg improved (P < 0.001) feed intake and growth performance in comparison to CON. The highest average daily gain and most efficient feed conversion ratio (linear, P < 0.001 and quadratic, P < 0.001) were found for TO1 followed by TO2, TO3 and POS, respectively. The incorporation of thyme oil improved (P < 0.001) carcass criteria and decreased (P < 0.001) perirenal and scapular fat without any side effects on internal organs. Notably, the water holding capacity of rabbit meat was greater (P < 0.001), and the lipid oxidation was lower (P < 0.01) in rabbits fed treated rations compared with CON. Differences were also recorded in oxymyoglobin and metmyoglobin contents in rabbit meat among treatments. In conclusion, thyme oil of a specified composition and to be added to a rabbit ration up to 100 mg/kg using 1.50 g/kg olive oil as a carrier can be used as an efficient feed additive for improving productive performance of rabbits under hot environmental conditions.

Use of olive leaves (whether or not fortified with sodium selenate) in rabbit feeding: Effect on performance, carcass and meat characteristics, and estimated indexes of fatty acid metabolism.

Sixty New Zealand White weaned rabbits were divided into three groups and subjected to different dietary treatments: a standard diet for the control (C), a standard feed supplemented with 10% of plain olive leaves (OL) and a standard feed supplemented with 10% of selenium-fortified olive leaves (100 mg/L of foliar spray sodium selenate solution; SeOL). The productive performance was recorded at the time of slaughter (after 35 days); the carcass and meat traits were determined and estimated indexes of fatty acid metabolism were calculated. No significant differences were found on the rabbit productive performance and the physical-chemical characteristics of the meat. Both group of rabbits on the enriched diet showed leaner and thinner carcasses and a higher meat concentration of oleic acid. The estimated index of Δ5 + Δ6-desaturase, starting from n-6 fatty acids, was lower in both groups supplemented with leaves. The use of selenium-fortified olive leaves, positively affected the lipid oxidative stability of rabbit meat.