Based on the knowledge of the heme bio-synthetic and metabolic pathway and the structures of biliverdin and protoporphyrin, experiments were carried out to compare the difference between the total quality of eggshell pigments in blue-shelled eggs and brown-shelled eggs from the same population (Dongxiang, China) and to analyze the correlation between the quantity of protoporphyrin and biliverdin in the 2 kinds of eggshells. It was found that there was no significant difference between the total quantity of eggshell pigments in Dongxiang blue-shelled eggs and Dongxiang brown-shelled eggs (P = 0.9006), and a highly significant positive correlation between the quantity of protoporphyrin and biliverdin in blue eggshells (P < 0.01) and a significant positive correlation between the quantity of protoporphyrin and biliverdin in brown eggshells (P < 0.05). These results suggested that eggshell protoporphyrin and eggshell biliverdin probably derived from common precursor material.
Crown gall induced by Agrobacterium vitis is a worldwide plant disease in grape-growing regions. Rahnella aquatilis HX2, a new isolate from vineyard soil in Beijing, showed a significant inhibition effect on the development of crown galls in grapevines. In field trials, immersion of the basal ends of grape cuttings with HX2 cell suspension inhibited or completely prevented crown gall formation caused by A. vitis K308 in the roots of the plants from the cuttings. The 3-year average disease incidence in grape plants treated with HX2 was 30.8% compared to 93.5% in plants without HX2. The culture supernatant of HX2 exhibited a stronger inhibition effect on disease development than did the cell suspension. HX2 could be found in the grape rhizosphere, grown under field conditions, for up to 90 days after inoculation. There was no significant difference in the mean population sizes of root microflora between plants treated and not treated with HX2. The inhibition effect of HX2 on crown gall in sunflower, caused by different agrobacterial strains, varied between 30.7 and 100%, depending on strains. Our results showed that Rahnella aquatilis HX2 may be used as a biological control agent for crown gall disease of grapes.
Five hundred and four 40-wk-old Brown Dwarf hens (1.51 +/- 0.08 kg BW) were fed corn-soybean meal diets containing 0, 1, 2, 3, 4, 5, or 6% conjugated linoleic acid (CLA) for 56 d to measure the effects of dietary CLA on laying hen productivity and egg quality during refrigerated storage. Four hens were placed in 1 cage, and 3 cages were grouped as 1 replicate resulting in 6 replicates per treatment. After feeding the experimental diets for 11 d, eggs were collected to determine the fatty acid composition of egg yolks. From d 12 to 18, eggs from hens fed diets containing 0, 2, 4, and 6% CLA diets were stored at 4 degrees C for up to 28 d. At designated times (1, 14, or 28 d), eggs were taken, broken, and shelled to evaluate water content, pH, and ion concentration. Firmness of hard-cooked egg yolk was also determined. With increased dietary CLA, feed intake, BW gain, rate of egg production, egg weight, and feed efficiency all decreased linearly (P < 0.01). The weight of the yolk, albumen, and shell decreased linearly (P < 0.01) with increasing dietary CLA. Concentration of CLA in the yolk lipids increased quadratically (P < 0.01), with increasing dietary CLA. Concurrent increases (P < 0.01) in the concentration of myristic, palmitic, and stearic acids and decreases (P < 0.01) in oleic, linoleic, linolenic, and archidonic acids in egg yolk lipids were observed. Days of storage and CLA (P < 0.01) increased yolk firmness. Egg yolk water content and pH increased with storage and CLA content (P < 0.01). Corresponding decreases were observed in albumen pH. Regardless of dietary treatment, the concentrations of Na, K, and Mg in egg yolks increased with longer storage time. At 28 d of storage, there was a linear (P < 0.01) increase in Na, K, and Mg content in egg yolks as dietary CLA increased. In contrast to the egg yolk, the concentrations of Na, K, and Mg in egg albumen decreased with storage time. On d 28, there was a linear decrease (P < 0.01) in the Na content of albumen with increasing CLA. This study suggests that the greater firmness of CLA-fed eggs might be related to the change of pH, water content, and ion concentrations during refrigerated storage.
The objective of the present study was to evaluate the role of myofiber characteristics and the thickness of 2 major muscle membranes, perimysium and endomysium, in determining the breast meat tenderness of chickens. Birds from 2 breeds (White Leghorn and a line of broiler) were chosen. Chicks were sexed and wing-banded at hatch and were grown in separate cages in a single house. Sixty broilers and 60 White Leghorns were harvested at 6 wk of age, respectively, whereas another 60 White Leghorns were slaughtered at 18 wk of age. An equal number of males and females was maintained for each group. Body weight, breast muscle weight, pH, drip loss, cooking loss, Warner-Bratzler shear force value (SFV), total energy of shear force, fiber diameter, sarcomere length, myofiber density, and the thickness of endomysium and perimysium of the breast were determined for each bird. At 6 wk of age, histological examination indicated that the size of myofiber and thickness of endomysium and perimysium of broilers were larger than that those of White Leghorns (P < 0.01), whereas the SFV, drip loss, and cooking loss of broilers were smaller (P < 0.01). A comparison between the White Leghorns at 18 wk and the broilers at 6 wk, which were at similar BW but different ages, showed that the breast muscle weight of broilers was larger (P < 0.01) than that of White Leghorns. For breast muscle, the endomysium of broilers at 6 wk was thicker than that of White Leghorns at 18 wk (P < 0.01), whereas the perimysium was thinner (P < 0.01). The SFV, drip loss, and the cooking loss of broilers were smaller than those of White Leghorns at similar BW (P < 0.01). Meat tenderness was negatively correlated with myofiber density (-0.27) and the thickness of endomysium (-0.29) and positively correlated with the thickness of perimysium (0.20). It is suggested that muscle membrane should be considered in evaluating meat tenderness of the chicken.
The peroxisome proliferators-activated receptor-gamma coactivator-1alpha (PGC-1alpha) was investigated as a candidate gene for growth and fatness traits in chicken because of its prominent role in muscle fiber specialization and adipogenesis. A single nucleotide polymorphism (SNP) from G to A at position 646 of the open reading frame of chicken PGC-1alpha gene causing an Asp216Asn amino acid substitution was identified. The frequencies of alleles and genotypes were significantly different among 6 chicken breeds (P < 0.01). The White Plymouth Rock had the highest frequency (0.67) of allele G, whereas the White Leghorn had the lowest (0.18). The associations of the SNP with the growth and fatness traits were evaluated in 332 F(2) birds from an experimental cross of White Plymouth Rock x Silkies. No association was found between the SNP and growth-related traits. However, abdominal fat weight at 12 wk of age for birds with genotype GG was 34.26 and 28.71% higher than those with genotypes AA and AG, respectively (P < 0.01), indicating that the Asp216Asn polymorphism of the PGC-1alpha gene could be used as a novel potential molecular marker for selection against abdominal fatness without interfering in regular breeding for growth rate of chickens.
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