Breast Muscle Yield Research Articles

Interactions Between Non-Allelic Loci and Their Effects on Categorized Meat Performance Traits in Ducks

ABSTRACT Traits associated with meat performance are characterized by a complex inheritance model, including the effects of non-allelic interactions. The aim of this study was to estimate the significance of non-allelic interactions between pairs of loci in each of two alternative groups based on four important performance traits of ducks: body weight (BW), carcass yield calculated as the ratio of carcass weight to body weight (CY), breast and leg muscle yield as a fraction of carcass weight (BL-CW), and skin weight and abdominal fat, again as a fraction of carcass weight (SF-CW). The experimental material was based on an F2 cross between two parental lines: A-55 (Polish Peking) and GL-30 (French Peking). In total, 368 individuals were recorded. All of the birds (including parents and F1) were genotyped for 23 polymorphic microsatellite loci. Entropy was taken as a measure of interaction between pairs of loci, and the chi-square test was used to verify significance. In total, 253 pairs of loci were analyzed in both categories of each of the four traits. Statistically significant interactions were obtained for each trait. However, it was observed that some of the loci showed a greater tendency to have significant opposite interactions for alternative categories of the same trait. The results indicate the dependence of the recombination rate within pairs of loci on the level of each of the four traits.

Response of broilers to gradual dietary protein reduction with or without an adequate glycine plus serine level

This study was aimed to probe broiler responses to the maintenance of adequate level of glycine plus serine in low crude protein (CP) diets by glycine (Gly) addition from 8 to 42 days of age. A total of 1152 7-d-old birds were divided into 8 groups and fed with one of the following diets: (I) normal CP diet; (II, III vIV V) diets with 1.5%, 3%, 4.5% and 6% points less CP than normal diet, respectively; (VI, VII, VIII) diets with 3%, 4.5% and 6% points reduced CP than the normal CP diet, respectively, and added with Gly to achieve 2.32% total Gly + Ser. Each treatment was replicated with 12 cages. Results showed that dietary CP reduction by 3% or higher compromised (p < .05) growth performance and carcase traits of broilers. Gly fortification in the diet with a 4.5% CP reduction produced similar accumulative growth performance relative to normal-CP group. When Gly fortification in the diet with a 6% CP reduction, the accumulative growth performance were improved (p < .05) but were still inferior (p < .05) to those in normal-CP group. Gly fortification supported a similar (p > .05) abdominal fat percentage of birds fed the diet containing 4.5% points less CP as compared with birds fed the normal-CP diet. Comparatively, Gly fortification in the diet with a 6% CP reduction resulted in breast muscle yield, serum UN content on d 21 and albumin content on d 42 comparable to (p > .05) those in normal-CP group. Collectively, the absence of Gly addition allowed dietary CP reduction by no more than 3% to obtain normal performance and carcase traits of broilers. Gly fortification in the diet with a 3% CP reduction induced no improvements in growth performance and carcase traits of broilers. However, maintain a level of 2.32% total Gly + Ser via Gly fortification enabled a reduction of dietary CP by 4.5% without deteriorating the accumulative growth performance and carcase traits of broilers. Highlights Gly addition that provides 2.32% total Gly + Ser allows dietary CP reduction of 4.5% without compromising the accumulative growth performance and carcase traits of broilers. Maintaining 2.32% total Gly + Ser via Gly fortification could not completely overcome the depression of growth performance in broilers fed the diet with a 6% CP reduction.

PSI-13 Allometric growth patterns in turkeys (Meleagris gallopavo) show no significant increase in total carcass meat yield

Abstract The body composition of livestock has been shown to change over time. Generally, bone maturation occurs first, followed by muscle growth. The objective of this study was to evaluate growth patterns of the most economically significant carcass components (pectoralis major, pectoralis minor, thigh, drum, and rack) in a commercial strain of turkeys. Live body weights and carcass component weights were collected on 1688 toms and 1085 hens between 2012 and 2017. Toms and hens were slaughtered between 109–149 days and 91–114 days of age, respectively. Yield values were calculated for each carcass component as a percentage of the live body weight. Regression coefficients (b) were calculated by regressing yield values on the age of the animal at slaughter. P. major and P. minor yield increased with age, though at different rates, for both toms (b=0.120, P &amp;lt; 0.01 and 0.003, P &amp;lt; 0.01, respectively) and hens (b=0.089, P &amp;lt; 0.01 and 0.020, P &amp;lt; 0.01, respectively). Tom drum and rack yield decreased with age (b=-0.012, P &amp;lt; 0.01 and -0.104, P &amp;lt; 0.01, respectively). Hen drum yield also decreased with age (b=-0.018, P &amp;lt; 0.01), while hen rack yield was found to not be significant from zero. Toms and hens showed similar trends of increasing breast yield with age and an equal combined decline in other carcass component yields. Thus resulting in a small significant increase in hen carcass meat yield (b=0.080, P &amp;lt; 0.01) and no significant increase in tom carcass meat yield (b=0.005, P &amp;gt; 0.01) which were both expected to increase with age given expected body composition changes over time. Strong selection for breast meat yield and the observed negative correlations between breast muscle yield and thigh and drum yields are likely the cause of this trend. Further research should investigate the use of carcass meat yield or other carcass component yields in turkey breeding programs.

Effects of stocking density on growth performance, growth regulatory factors, and endocrine hormones in broilers under appropriate environments

Stocking density is an important environment factor that affects the development of poultry farming, which has caused widespread concern. This study was carried out to determine the effects of stocking density on growth performance, growth regulatory factors, and endocrine hormones in broilers under appropriate environments. A total of 144 Arbor Acres male broilers (BW 1000 ± 70 g) were randomly divided into low stocking density (LSD; 6.25 birds/m2), medium stocking density (MSD; 12.50 birds/m2), and high stocking density (HSD; 18.75 birds/m2) groups, with 6 replicates in each group, and raised in 3 environmental chambers (same size) from 29-day-old to 42-day-old, respectively. The trial period lasted for 14 D with 21 ± 1°C and 60 ± 7% relative humidity, wind speed < 0.5 m/s, ammonia level<5 ppm. The results indicated that average daily food intake and average daily gain in HSD group showed significantly lower than other 2 groups (P < 0.05). Besides, the HSD group significantly reduced breast muscle yield, tibial length, tibial width, and tibial weight of broilers (P < 0.05). The HSD group increased the mRNA expression level of myostatin, and reduced the mRNA expression levels of insulin-like growth factor 1 (IGF-1) and myogenic determination factor 1 (P < 0.05). The HSD group significantly reduced the expression of parathyroid hormone-related protein in tibial growth plate (P < 0.05). The HSD group increased the serum corticosterone levels of broilers (P < 0.05), and decreased the serum IGF-1 and thyroxine (T4) levels of broiler chickens (P < 0.05) than other stocking density groups. Moreover, the serum alkaline phosphatase levels were decreased (P < 0.05) with increasing stocking density, whereas there were no significant effects on the serum 3,5,3′-triiodothyronine (T3) concentrations in 3 groups (P > 0.05). In conclusion, under appropriate environments HSD reduced the growth performance of broilers and this negative effect was likely associated with decreased growth of muscle and bone.

Effect of in ovo feeding of β-hydroxy-β-methylbutyrate on hatchability, muscle growth and performance in prenatal and posthatch broilers.

β-Hydroxy-β-methylbutyrate (HMB) is the metabolite of leucine that plays an important role in muscle protein metabolism. The objective of the present study was to determine the effects of in ovo feeding (IOF) of HMB at 7 days of incubation (DOI) via air cell or 18 DOI via amnion on hatchability, muscle growth and performance in prenatal and posthatch broilers. IOF of HMB via air cell at 7 DOI increased hatchability by 4.34% compared with the control (89.67% versus 85.33%). Birds in IOF groups exhibited higher body weight, average daily body weight gain and pectoral muscle percentage. Furthermore, IOF of HMB significantly increased the level of plasma growth hormone, insulin and insulin-like growth factor-1. Chicks hatched from IOF treatment had larger diameters of muscle fiber and higher mitotic activity of satellite cells at early posthatch age. IOF of HMB activated satellite cells by upregulation of mRNA expression of myogenic transcription factors, myogenic differentiation one (MyoD) and myogenin. Chicks hatched from air cell injection group had higher pectoral muscle percentage at 5d posthatch and greater satellite cell mitotic activity at 7d posthatch than counterparts from amnion injection group. IOF of HMB via amnion at 18 DOI or especially via air cell at 7 DOI could be used as an effective approach to enhance hatchability, productive performance and breast muscle yield in broilers. © 2019 Society of Chemical Industry.

Leucine promotes the growth of squabs by increasing crop milk protein synthesis through the TOR signaling pathway in the domestic pigeon (Columba livia)

Leucine (Leu) plays a critical regulatory role in protein synthesis, however, the effects and molecular mechanisms of Leu on crop milk protein in the domestic pigeons (Columba livia) are still unknown. Therefore, the study aimed to investigate the effects of dietary Leu supplementation on crop milk protein synthesis and the growth performance of squabs and the possible underlying mechanism. A total of 240 pairs of breeding pigeons (1102.3 ± 9.5g/pair) were randomly assigned to 1 of 5 treatments, including a positive control (PC) diet that had adequate crude protein (crude protein, CP = 18%; Leu = 1.30%), a negative control (NC) diet that was low in CP (CP = 16%, Leu = 1.30%), and NC diets supplemented with Leu at 0.15%, 0.45%, or 1.05%. Compared with the NC diet, 0.15 to 0.45% Leu supplementation decreased BW loss and increased relative crop weight, crop thickness, and protein levels in the crop tissue and milk of breeding pigeons. However, dietary supplementation with 1.05% Leu inhibited ADFI in breeding pigeons. Dietary supplementation with 0.15 to 0.45% Leu decreased the mortality rate and increased the BW, eviscerated yield, and breast muscle yield of young squabs. The protein expression levels of the target of rapamycin (TOR), ribosomal protein S6 kinase 1 (S6K1), ribosomal protein S6 kinase (S6), eukaryotic initiation factor 4E binding protein 1 (4EBP1), and eukaryotic translation initiation factor 4E (eIF4E) were upregulated in the crop tissue of breeding pigeons in PC, 0.15% and 0.45% Leu-supplemented groups. Collectively, these results indicated that 0.15 to 0.45% Leu supplementation could decrease BW loss, increase milk protein synthesis in the crop of breeding pigeons, and enhance the survival rate and growth performance of young squabs through the TOR signaling pathway.

Effects of Dietary Supplementation with dl-Methionine and dl-Methionyl-dl-Methionine in Breeding Pigeons on the Carcass Characteristics, Meat Quality and Antioxidant Activity of Squabs.

This study aimed to investigate the effects of dietary supplementation with dl-methionine (dl-Met) and dl-methionyl-dl-methionine (dl-Met-Met) in breeding pigeons on the carcass characteristics, meat quality and antioxidant activity of squabs. A total of 324 pairs of breeding pigeons were selected and allotted to 9 treatments in a completely randomized design, and the birds were fed dietary treatments for 45 d, including a Met-deficient basal diet (BD, crude protein = 15%, Met = 0.25%) and BD + 0.15%, 0.30%, 0.45%, or 0.60% dl-Met or dl-Met-Met diets. Compared with the diet fed to the BD group, dietary dl-Met or dl-Met-Met supplementation effectively increased the carcass yield, semieviscerated yield, eviscerated yield, breast muscle yield, thigh muscle yield, a* value, catalase activity, total superoxide dismutase activity and glutathione peroxidase activity, but decreased the L* value, malonaldehyde concentration, drip loss and cooking loss of squabs (p < 0.05). The relative bioavailability values of dl-Met-Met relative to those of dl-Met were 467% and 376% based on carcass yield and breast muscle yield, respectively (p < 0.001). Moreover, dl-Met-Met was more effective than dl-Met in decreasing the drip loss and improving the antioxidant activity of the breast and thigh muscles of squabs (p < 0.05). As a source of Met, dl-Met-Met, rather than dl-Met, was more beneficial to squabs.

From muscle to food: oxidative challenges and developmental anomalies in poultry breast muscle

The glycolytic capacity in the "white muscle fibers" found predominantly in broiler and turkey breast muscle have long been recognized as being key components contributing to optimal pH changes post-harvest and the quality of breast muscle products. The pectoralis major (PMAJ) is the predominant breast muscle and is almost exclusively comprised of fast-twitch glycolytic (anaerobic) type IIb muscle fibers (white). In nature, the pectoralis muscles are designed to meet the intense, periodic energy demands of flight in contrast to the continual, oxidative metabolism (aerobic) inherent to the type I slow twitch fibers (red) in the thigh and drum. Within the past decade, it has been recognized that increased breast muscle yield in modern broiler strains may have contributed to muscle myopathies characterized by visible white striations (white striping; WS) often accompanied by surface hemorrhages and areas of extreme firmness (woody breast; WB). The research to date has primarily addressed differences in muscle physiology and processing characteristics in "normal" and "abnormal" muscle samples from older broilers. One hypothesis is that the extensive accretion of protein in a poorly vascularized breast muscle overwhelms the capacity for coping with excessive production of reactive oxygen species and the term "oxidative stress" has been used to describe this condition. There are few recent reports in poultry, however, which have addressed the potential negative physiological effects imposed by multiple layers of fascia surrounding individual muscle fibers, fiber bundles, and intact muscles on circulation and oxidative stability. The objective of this review is to support our hypothesis that the extensive accretion of breast muscle in a poorly vascularized and tightly bound PMAJ could be creating a "compartment syndrome" like condition leading to the development of the WS and WB anomalies in heavy, high yielding birds. Recent gene expression data support this hypothesis.

Effects of dietary supplementation with betaine on muscle growth, muscle amino acid contents and meat quality in Cherry Valley ducks.

The effects of dietary betaine supplementationon growth performance, carcass characteristics, muscle amino acid contents, meat quality, antioxidant capacity, myogenic gene expression and mechanistic target of rapamycin (mTOR) signalling pathway in Cherry Valley ducks were evaluated. A total of 720 1-day-old Cherry Valley ducks were randomly distributed into four groups with six replicates of 30 birds for a 42-day feeding trial. Ducks were fed a basal diet supplemented with 0 (control), 250, 500 or 1,000mg/kg betaine, respectively. Growth performance was not affected by betaine. Incremental levels of betaine linearly (p<0.05) increased the breast muscle yield and linearly (p<0.05) decreased the subcutaneous fat thickness and the abdominal fat yield. The contents of methionine, serine, glycine, glutamate and total non-essential amino acid in breast muscle were linearly (p<0.05) increased by betaine supplementation. With increasing betaine levels, the drip loss and the content of malondialdehyde (MDA) were linearly (p<0.05) decreased, and the redness of meat (linear p<0.05), the activities of catalase (CAT) (linear p<0.05) and total superoxide dismutase (T-SOD) (linear p<0.05, quadratic p<0.05) were increased. Moreover, the myogenic differentiation factor 1 (MyoD1) mRNA expression and the mTOR mRNA expression and protein phosporylation were linearly (p<0.05) up-regulated, and the myostatin (MSTN) mRNA expression was linearly (p<0.05) down-regulatedby betaine supplementation. Overall, this study indicated that betaine supplementation did not affect the growth performance of Cherry Valley ducks, but could linearly increase some amino acid contents in breast muscle, especially glycine, and increase muscle antioxidant activity to improve meat quality. Moreover, betaine supplementation could improve the breast muscle yield by increasing MyoD1 mRNA expression, decreasing MSTN mRNA expression and regulating mTOR signalling pathway.

White striping and wooden breast myopathies of broiler breast muscle is affected by time-limited feeding, genetic background, and egg storage

The effects of time-limited feeding, genetic background, and egg storage on white striping (WS) and wooden breast (WB) in broilers were studied. Male chicks (240) from 2 genetic backgrounds and 2 egg storage periods were fed on either an ad libitum (AL) or time-limited (TL) program from 7 d of age. A rapid growth strain (Growth) and an enhanced yield strain (Yield) of broiler breeder males were mated to a single female line and eggs were stored for periods of either 1 to 7 d or 8 to 14 d. Body weight (BW), feed consumption, and feed conversion ratio (FCR) were determined weekly. Carcass data including WS and WB scores were collected at 42 d of age. Breast muscle scoring was conducted either visually or by hand palpation using a 1 to 4 point ordinal scale (normal to greatest severity). Data were analyzed using the Mixed procedure of SAS. The TL fed broilers presented less WS (1.64 vs. 2.87) and WB (2.14 vs. 2.89), lower BW (2.99 vs. 3.27kg), and improved FCR (1.55 vs. 1.58 g: g), as well as reduced dressing percentage (79.5 vs. 80.1%), breast muscle yield (33.3 vs. 34.6%), and 24h muscle pH (5.82 vs. 5.95) relative to AL broilers (P < 0.01). Yield broilers exhibited reduced BW (2.97 vs. 3.28kg), lower WS (2.04 vs. 2.47), and greater WB (2.65 vs. 2.38) (P < 0.05) but similar dressing percentage (80.0 vs. 79.7%) and breast muscle yield (34.3 vs. 33.6%) when compared to Growth broilers. Longer egg storage generated lower BW (3.07 vs. 3.18kg) and when fed AL, an increased WS score (2.58 vs. 3.15) compared to the shorter egg storage period (P < 0.05). It was concluded that WS and WB could be reduced by TL feeding and that genetic background and egg storage period may influence the expression of WS and WB.

Wooden breast myopathy links with poorer gait in broiler chickens

Wooden breast myopathy, a condition where broiler breast muscles show a hardened consistency post-mortem, has been described recently. However, it is not known how wooden breast myopathy affects the bird activity or welfare. Altogether, over 340 birds of five commonly used commercial hybrids were housed in 25 pens, and sample birds killed at ages of 22, 32, 36, 39 and 43 days. Their breast muscle condition was assessed post-mortem by palpation. The birds were gait scored and their latency to lie was measured before killing. For further behavior observations, one affected and healthy bird in 12 pens were followed on 5 days for 20 minutes using video recordings. The connection of myopathy to gait score and activity was analyzed with mixed models. A higher gait score of wooden-breast-affected birds than that of unaffected birds (2.9 ± 0.1 v. 2.6 ± 0.1, P < 0.05) indicated a higher level of locomotor difficulties over all age groups. The wooden-breast-affected birds had fewer crawling or movement bouts while lying down compared with unaffected (P < 0.05). Wooden breast myopathy-affected birds were heavier (2774 ± 91 v. 2620 ± 91 g; P < 0.05) and had higher breast muscle yield (21 ± 1 v. 19 ± 1%; P < 0.05) than unaffected birds overall. Older birds had longer lying bouts, longer total lying time, fewer walking bouts, more difficulties to walk and to stand compared with younger birds (P < 0.05). Birds with poorer gait had longer total lying time and fewer walking bouts (P < 0.05). Birds with greatest breast muscle yield had the largest number of lying bouts (P < 0.05). It was concluded that wooden breast myopathy was associated with an impairment of gait scores, and may thus be partly linked to the common walking abnormalities in broilers.

Chronic heat stress affects muscle hypertrophy, muscle protein synthesis and uptake of amino acid in broilers via insulin like growth factor-mammalian target of rapamycin signal pathway

Heat stress markedly impairs the growth performance of broilers, such as the reduction of breast muscle mass and yield. The aim of this study was to examine the molecular mechanism of depressed muscle mass and yield caused by heat stress. A total of 144 (28-day-old) male broilers were allocated randomly into 3 treatment groups: (1) the normal control group (environment temperature was 22°C), (2) the heat stress group (environment temperature was 32°C), (3) the pair-fed group (environment temperature was 22°C and pair-fed to heat stress group). The experiment lasted for 14 d (from the age of 28 to 42 d). After 14 d of heat exposure, heat stress decreased (P < 0.05) broiler average daily gain, breast muscle mass, and muscle yield, and increased (P < 0.05) feed to gain ratio. After 14 d of heat exposure, heat stress increased (P < 0.05) the activities of aspartate aminotransferase and the concentrations of uric acid and most amino acids in serum, and reduced (P < 0.05) the concentration of insulin like growth factor 1 (IGF-1) in serum. Additionally, heat stress decreased (P < 0.05) the mRNA expressions of IGF-1, IGF-1 receptor, insulin receptor substrate 1, mammalian target of rapamycin (mTOR), the 70kD ribosomal protein S6 kinase, myogenic differentiation, myogenin, solute carrier family 38 member 2, solute carrier family 7 member 5, and solute carrier family 3 member 2 of the breast muscle. In conclusion, chronic heat stress resulted in lower breast muscle mass and yield, and decreased muscle protein synthesis and amino acid transportation by downregulating IGFs-mTOR signal pathway. These findings have important practical significance in discovering effective means to alleviate muscle loss caused by chronic heat stress.

Betaine improves the growth performance and muscle growth of partridge shank broiler chickens via altering myogenic gene expression and insulin-like growth factor-1 signaling pathway

This study was conducted to investigate the effect of betaine on growth performance, carcass characteristics, myogenic gene expression, and insulin-like growth factor-1 (IGF-1) signaling pathway in partridge shank broiler chickens. A total of 192 one-day-old partridge shank broiler chickens were randomly divided into 4 groups with 6 replicates of 8 chickens for a 52-d feeding trial. Broilers were fed a basal diet supplemented with 0 (control), 250 (B250), 500 (B500), or 1,000 (B1000) mg/kg betaine. Compared with the control group, the B500 and B1000 groups had higher (P < 0.05) body weight gain (BWG), and the B500 group had a lower (P < 0.05) feed/gain ratio (F:G) during the whole trial period. Moreover, the B1000 group increased (P < 0.05) the breast muscle yield and decreased (P < 0.05) relative abdominal fat weight. The mRNA expression of myocyte enhancer factor 2B (MEF2B) and mechanistic target of rapamycin (mTOR) and mTOR phosporylation were higher (P < 0.05) in both breast and thigh muscles in the B500 and B1000 groups than those in the control group. The higher (P < 0.05) concentration and mRNA expression of IGF-1 were also observed in breast muscle in the B500 and B1000 groups. Additionally, the B1000 group up-regulated (P < 0.05) the mRNA level of myogenic differentiation factor 1 (MyoD1) in breast muscle and myogenin (MyoG) in thigh muscle. In conclusion, diets supplemented with 500 or 1,000 mg/kg betaine improved the growth performance of partridge shank broiler chickens during the whole trial period, and the B1000 group significantly improved the breast muscle growth. These improvements might result from increased mRNA expression of MyoD1 and MEF2B in breast muscle and MyoG and MEF2B in thigh muscle, and through alterations in IGF-1/mTOR signaling pathway.

RNA-Seq transcriptome analysis of breast muscle in Pekin ducks supplemented with the dietary probiotic Clostridium butyricum

BackgroundIncreased attention is being paid to breast muscle yield and meat quality in the duck breeding industry. Our previous report has demonstrated that dietary Clostridium butyricum (C. butyricum) can improve meat quality of Pekin ducks. However, the potential biological processes and molecular mechanisms that are modulated by dietary C. butyricum in the breast muscle of Pekin ducks remain unknown.ResultsSupplementation with C. butyricum increased growth performance and meat yield. Therefore, we utilized de novo assembly methods to analyze the RNA-Seq transcriptome profiles in breast muscle to explore the differentially expressed genes between C. butyricum-treated and control Pekin ducks. A total of 1119 differentially expressed candidate genes were found of which 403 genes were significantly up-regulated and 716 genes were significantly down-regulated significantly. qRT-PCR analysis was used to confirm the accuracy of the of RNA-Seq results. GO annotations revealed potential genes, processes and pathways that may participate in meat quality and muscle development. KEGG pathway analysis showed that the differentially expressed genes participated in numerous pathways related to muscle development, including ECM-receptor interaction, the MAPK signaling pathway and the TNF signaling pathway.ConclusionsThis study suggests that long-time dietary supplementation with C. butyricum can modulate muscle development and meat quality via altering the expression patterns of genes involved in crucial metabolic pathways. The findings presented here provide unique insights into the molecular mechanisms of muscle development in Pekin ducks in response to dietary C. butyricum.

The Incidence of Muscle Abnormalities in Broiler Breast Meat - A Review.

The dramatic improvements in the growth rate and breast muscle size and yield in broilers through the intensive genetic selection, and the improvement in nutrition and management over the past 50 years have introduced serious abnormalities that influenced the quality of breast meat. The abnormalities include pale-soft-exudative (PSE) conditions, deep pectoral muscle (DPM) myopathy, spaghetti meat (SM), white striping (WS), and woody breast (WB) that have serious negative implications to the broiler meat industry. The incidences of PSE and DPM have been known for several decades, and their prevalence, etiology and economic impact have been well discussed. However, other abnormalities such as SM, WS and WB conditions have been reported just for few years although these conditions have been known for some time. The newly emerging quality issues in broilers are mainly associated with the Pectoralis major muscles, and the incidences have been increased dramatically in some regions of the world in recent years. As high as 90% of the broilers are affected by the abnormalities, which are expected to cause from $200 million to $1 billion economic losses to the U.S. poultry industry per year. So, this review mainly discusses the histopathological characteristics and biochemical changes in the breast muscles with the emphasis on the newly emerging abnormalities (SM, WS, and WB) although other abnormalities are also discussed. The impacts of the anomalies on the nutritional, functional, mechanical and sensory quality of the meat and their implications to the poultry industry are discussed.

Comparative Study of Different Maternal Zinc Resource Supplementation on Performance and Breast Muscle Development of their Offspring.

Maternal zinc supplementation has a pivotal role in enhancing breast muscle development of the offspring. What is poorly defined is the impact of supplemental zinc from different sources on the offspring. Broiler breeders at 24-week-old were randomly divided into three treatments with six replicates of 40 hens each and respectively fed for 8weeks with supplemental 0-(group Zn/C), 100mg/kg organic-(group Zn/O), and 100mg/kg inorganic-(group Zn/I) zinc. The male offspring from each nutritional treatment were allocated into eight cages of 14 birds each, and a commercial diet supplemented with zinc from ZnSO4 at 20mg/kg was fed to the offsprings. Results showed that eggs from Zn/O group had the highest zinc deposition (P < 0.05). Furthermore, maternal zinc supplementation promoted breast muscle yield; increased serum insulin and IGF-I concentration; upregulated AKT, mTOR, and P70S6K mRNA levels; and improved the phosphorylation of AKT at Serine 473 residue, mTOR at Serine 2448 residue, and FOXO at Serine 256 residue in the breast muscles of the offspring. In contrast, hens' diet supplemented with zinc could result in downregulation of atrogin-1 and MuRF1 mRNA levels in the breast muscle of the offspring. Additionally, no significant effect on breast muscle development post-hatch was observed between organic and inorganic zinc supplementation. In conclusion, maternal organic zinc supplementation improved zinc deposition in egg; however, no significant difference was detected in breast muscle development of the offspring of broiler breeder between organic and inorganic zinc supplementation.

Osmoregulatory function of betaine in alleviating heat stress in poultry.

This review focuses on the osmoregulatory function of betaine and its effect in terms of alleviating heat stress in poultry. Poultry appear to be particularly sensitive to temperature-associated environmental challenges, especially heat stress. High ambient temperatures are deleterious to productive performance in poultry, including broilers, laying hens, quails and turkeys, resulting in considerable economic losses. Heat stress impairs overall poultry production by decreasing feed intake and negatively affecting intestinal development, leading to reduced nutrient digestibility. Apart from inducing a high mortality rate, heat stress is known to depress growth rate and reduce meat yield in broilers. In layers, lower feed intake impairs ovarian function, leading to decreased feed efficiency, egg production and egg quality. In addition, reduced immune functions, such as thyroid activity and antibody production, are evident in poultry exposed to heat stress. Heat stress increases the production of oxidants, causing oxidative stress and lipid peroxidation of cell membranes. Poultry respond physiologically and behaviourally when encountering the negative effects of heat stress, attempting to return the body to homeostasis. This requires energy at the expense of weight gain or egg production. Due to its zwitterionic structure, betaine has osmoprotective properties that aid in protecting intestinal cell proteins and enzymes from environmental stress, including high ambient temperature, thereby counteracting performance losses. Betaine also exerts an osmoregulatory role in cells, regulating water balance, and this results in more stable tissue metabolism. Inclusion of betaine in the diet may be beneficial for alleviating physical reactions to heat stress, as indicated by increases in nutrient digestibility. In broilers, betaine supplementation increases weight gain and breast muscle yield, while improving feed conversion. In layers, betaine supplementation improves egg production, egg quality traits and immune indices. In conclusion, due to its osmoregulatory functions, betaine plays an important role in alleviating heat stress in poultry.

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 0.2mL solution containing: 3.5mg/embryo BI (Bi2tos, trans-galactooligosaccharides); 0.88mg/embryo DN (DiNovo, extract of Laminaria spp.); 1.9mg/embryo RFO (raffinose family oligosaccharides) and 0.2mL 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.

The Effect of Amaranth Seeds, Sea Buckthorn Pomace and Black Chokeberry Pomace in Feed Mixtures for Broiler Chickens on Productive Performance, Carcass Characteristics and Selected Indicators of Meat Quality

Abstract The aim of the present study was to determine the effect of amaranth seeds, dried sea buckthorn pomace and dried chokeberry pomace on the growth performance of broiler chickens and on the fatty acid profile and oxidative stability of meat lipids. The study was conducted on 480 Ross 308 chickens assigned in the second production phase to 4 experimental groups. The birds from the control group received 3% flax oil, while the chickens from the experimental groups were fed with mixtures containing: 3% flax oil and 8% amaranth seeds (group II), 3% flax oil and 3% dried sea buckthorn pomace (group III), and 3% flax oil and 3% dried chokeberry pomace (group IV). Basic production parameters were evaluated for each feeding period. At 42 days of age, 8 birds with body weight close to the average from each group were slaughtered. A simplified analysis of the chicken carcasses was conducted and samples of the breast muscles were collected for further analysis. The addition of 8% amaranth seeds into the feed mixtures in the second feeding phase decreased body weight gains (P&lt;0.05) and increased the feed conversion ratio compared with groups receiving sea buckthorn or chokeberry pomace. However, the addition of amaranth seeds into the feed mixtures increased breast muscle yield (P&lt;0.05) and decreased fat content in comparison to the other experimental groups. Moreover, sensory analysis of the breast muscles from chickens fed the diet with amaranth seeds revealed that they were characterised by a better aroma (P&lt;0.05) and flavour. The studied feed additives did not significantly affect the physicochemical properties of the breast muscles. Sea buckthorn pomace efficiently slowed down lipid oxidation in the breast muscles. The obtained results indicate that using tested plant additives in feed mixture may be an effective way to improved production parameters of broiler chicken and effectively enriched meat in n-3 fatty acid and protect against excessive oxidation of lipids.

Effect of dietary β-alanine supplementation on growth performance, meat quality, carnosine content, and gene expression of carnosine-related enzymes in broilers

The objective of the current study was to investigate the effect of dietary β-alanine supplementation on growth performance, meat quality, antioxidant ability, carnosine content, and gene expression of carnosine-related enzymes in broiler chicks. We randomly assigned 540 1-day-old Arbor Acres broilers to 5 dietary treatments supplemented with 0 (control group), 250, 500, 1,000, or 2,000mg/kg of β-alanine (mg β-alanine per kg feed). Each treatment included 6 replicates of 18 birds. The feeding trial lasted for 42 d. Dietary β-alanine supplementation linearly and quadratically increased the average daily gain (ADG) during the starting period (d1 to 21, P = 0.02 and P = 0.002). The feed conversion ratio (FCR) decreased quadratically in response to dietary β-alanine supplementation during the starting and entire periods (P < 0.001 and P = 0.003, respectively). For the entire period, the predicted best FCR would be achieved when β-alanine was fed at a level of 1,100mg/kg from quadratic regression. The concentrations of carnosine and β-alanine in breast muscle increased quadratically with dietary β-alanine supplementation (d 42, P < 0.001 and P = 0.001, respectively). The predicted dietary β-alanine level for highest breast carnosine content was 1,196mg/kg. Dietary supplementation with β-alanine reduced the taurine concentrations in plasma (d 42, linear and quadratic, P <0.001). Breast muscle yield increased linearly and quadratically in response to dietary β-alanine addition (d 21, P = 0.017 and P = 0.007). Dietary supplementation with β-alanine quadratically reduced the shear force (P = 0.003), whereas a*45min and a*24h values increased quadratically in response to dietary β-alanine supplementation (d 42, P = 0.020 and P = 0.021, respectively). Dietary β-alanine addition quadratically enhanced the expression of carnosine synthase and taurine transporter mRNAs (P < 0.05). Overall, dietary β-alanine supplementation improved growth performance and carnosine content, ameliorated antioxidant capacity and meat quality, and upregulated the gene expression of carnosine synthesis-related enzymes in broiler chicks.