On the basis of meat quality traits, muscle fiber characteristics, and nutrient components and contents in chickens at market age, 120-d-old Beijing-you (BJY) chickens (the Chinese local breed) had distinct breast muscle features when compared with 42-d-old Arbor Acres (AA) chickens (the genetically improved broiler line). The phospholipid (P < 0.05) and essential fatty acid (P < 0.05) contents in BJY chickens were significantly higher than those in AA chickens. No differences (P > 0.05) were found between the breeds in the contents of polyunsaturated fatty acids, unsaturated fatty acids, protein, or amino acids. Breast muscle fiber diameter was significantly smaller (~55.76%) and fiber density was higher (~174.86%) in BJY chickens than in AA chickens (P < 0.05). In this study, breast muscle from 120-d-old BJY chickens was judged to have better quality of phospholipids and essential fatty acid contents and muscle fiber characteristics than breast muscle from 42-d-old AA chickens.
This paper, the second from a comprehensive study, describes the effects of varying growth rate by feeding at different planes of nutrition with a constant ME:CP ratio on muscle characteristics and meat quality in 2 distinct broiler breeds of male chickens (Arbor Acres, a commercial line; and Beijing-You, a Chinese nonimproved line). Experimental diets, differing on average by 2% CP, were formulated with high-, medium-, or low-nutrient densities for 3 growing phases. Male hatchlings (216 of each breed) were randomly assigned to 6 pens of 12 birds in each treatment. Altered histological characteristics of muscle fibers, early postmortem muscle metabolism, and meat quality were investigated in the pectoralis major and biceps femoris. At their market age, Arbor Acres broilers had significantly higher concentrations of plasma protein and lipid metabolites, ratios of white to red and intermediate fibers, pH, L* and b* values, and lower concentrations of plasma glucose metabolites, muscle-fiber diameter, muscle contents of energy stores, a* value, drip loss, and shear force than the values found for the Beijing-You chickens (P < 0.01). Higher nutrient density increased the size of the muscle fibers, decreased glycogen reserve, and reduced the rate and extent of acidification in the Arbor Acres chickens, while accelerating transformation of red and intermediate-to-white fibers, enhancing energy stores, and hastening the decrease in pH postmortem in the Beijing-You chickens (P < 0.05). In each breed, most meat quality variables (e.g., shear force, drip loss, and color) were consistent with the histological and biochemical changes caused by the feeding strategy. Together, dietary nutrient density can influence meat quality as a result of altered histological and initial energy and metabolic characteristics of the muscle. Many of the responses to diet are breed and tissue dependent in broiler chickens.
By estimating the genetic parameters of various semen quality traits in Beijing-You chickens, this study aims to elucidate the inheritance patterns of these traits and the correlations between them to facilitate setting up appropriate breeding strategies for enhanced semen quality. Semen samples were collected from 518 Beijing-You roosters at 43 wk of age from 3 selection lines related to meat flavor traits. Seven semen quality traits, consisting of semen volume, pH, and color, and sperm viability, motility, percent deformity, and concentration, were determined. Sizeable variations (18-24% CV) were observed for all traits, except for semen pH. The effects of semen collection time and origin of the chickens (line) were analyzed to optimize the proper models for estimating genetic parameters for each trait. The multiple-trait derivative-free restricted maximum likelihood method was used for estimating variance components. The results revealed that sperm viability, motility, and percent deformity exhibited high heritabilities (h(2) = 0.52, 0.85, and 0.60, respectively). Semen volume, semen color, and sperm concentration had moderate heritabilities (h(2) = 0.28, 0.19, and 0.12, respectively). Semen pH showed low heritability (h(2) = 0.03). Genetic and phenotypic correlations between sperm motility and viability were positive and high (rA = 0.88 and rP = 0.59). In addition, these 2 traits were genetically negatively correlated with percent deformity. This implied the possibility of reducing sperm deformity, which is difficult to measure, by indirect selection. It is concluded from this study that semen quality can be improved by selection. The traits with high variations and heritabilities such as semen volume are promising traits for selection to improve semen quality and likely reproductive performance of native chicken breeds.
This study aimed to evaluate the influence of supplemental dietary nicotinic acid (NA) on lipid metabolism and hepatic expression of related genes in female chickens of two distinct broiler strains [Arbor Acres (AA) and Beijing-You (BJY)]. The treatments were arranged in a 2 × 4 factorial in a completely randomized design. Day-old females (n = 384) were allocated to four treatments with six cages per treatment and fed diets (basal contained approximately 25 mg NA/kg) supplemented with 0, 30, 60 and 120 mg NA/kg. A sample of 72 birds from each breed was slaughtered and sampled at their different market times (8 week for AA and 16 week for BJY). Arbor Acres broilers had thickness of subcutaneous fat plus the skin (SFS), and plasma concentration of low-density lipoprotein cholesterol (LDLC) and lower percentage of abdominal fat (PAF), plasma concentrations of TG, NEFA and adiponectin than the BJY line. The hepatic transcription of apolipoprotein A-I (ApoA-I), apolipoproteinB (ApoB), and adiponectin was significantly higher in AA broilers than in BJY broilers. In both breeds, BW, PAF, SFS, NEFA and TG were increased with increasing supplementation from 0 to 60 mg NA/kg, but then decreased slightly with 120 mg added NA/kg. With increasing supplementation, hepatic expression and plasma concentrations of adiponectin decreased from 0 to 60 mg added NA/kg and then increased with 120 mg added NA/kg. The expression of ApoA-I and ApoB mRNA showed linear response to dietary supplementation with NA. These findings indicate that: (i) supplementation of NA influenced the lipid metabolism and related gene expression; (ii) when supplemented with 120 mg NA/kg, some pharmacologic actions on lipid metabolism appeared; and (iii) changes in BW and fat deposition appeared to be associated with hepatic expression of adiponectin.
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