Chlamydiosis in layer chickens.
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Animals↗
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Dietary prilled fat and layer chicken performance and egg composition.
Prilled and poultry fat were fed at 2% to 58-wk-old hens and at 4% to 2-wk-old hens for 8 wk. Comparisons by dietary fat source were made within age groups for BW, feed consumption, egg production, egg weight, yolk cholesterol, and fatty acid composition, egg quality, plasma cholesterol, dietary fatty acid utilization, dietary ME, and gastrointestinal transit time of feed. Old hens fed prilled fat had lower egg weight, increased egg production, lower plasma high density lipoprotein (HDL) cholesterol (P < 0.08), and reduced energy. Young hens fed prilled fat were lighter in weight and had lower plasma total and low density and very low density lipoprotein cholesterol. Young hens fed prilled fat had a lower utilization of stearic acid (P < 0.07) but a higher utilization of linoleic acid. In both groups, prilled fat increased yolk saturated fatty acids and decreased polyunsaturated fatty acids. Gastrointestinal transit time of feed was increased by 29 to 31 min (P < 0.09) in young hens fed prilled fat.
Aging↗
Effects of age at inoculation and induced molt on the recovery of Mycoplasma gallisepticum from layer chickens.
An experiment was conducted to determine the effects of age at inoculation and induced molt on the reisolation of Mycoplasma gallisepticum (MG) from commercial leghorn hens that had been eyedrop-inoculated with F strain MG at either 10 or 66 wk of age. Chickens were maintained in biological isolation units from 10 wk of age through 78 wk of age. At 70 wk of age (premolt), hens were swabbed, cultured for MG, and molted. Swabs were taken both at the end of molt (postmolt [74 wk]) and again 4 wk later (postmolt+4 [78 wk]). A significant (P < or = 0.05) decrease in MG isolations was observed in the postmolt swabs as compared with the premolt swabs of hens inoculated at either 10 or 66 wk of age. A significant (P < or = 0.05) increase in isolations was observed in the postmolt+4 swabs as compared with the postmolt swabs of hens inoculated at either 10 or 66 wk of age. For the hens inoculated at 10 wk, no significant difference was found in premolt as compared with postmolt+4 MG isolations; however, for hens inoculated at 66 wk, a significant (P < or = 0.05) decrease was observed between premolt and postmolt+4 isolations. Significantly (P < or = 0.05) fewer MG isolations were obtained from the premolt swabs of hens inoculated at 10 wk as compared with hens inoculated at 66 wk. No significant difference in MG isolations was observed in either the postmolt or postmolt+4 swabs between hens inoculated at either 10 or 66 wk.
Aging↗
Cheilospirura species (gizzard worm) infection in battery-caged commercial layer chickens.
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Animal Husbandry↗
Efficacy of experimental inactivated mycoplasma gallisepticum oil-emulsion bacterin in egg-layer chickens.
Six groups of white leghorn pullets were studied to determine the ability of beta-propiolactone-inactivated Mycoplasma gallisepticum (MG) oil-emulsion bacterins to counteract reductions in egg production caused by MG infection. The pullets were inoculated with 0.5 ml of MG bacterin subcutaneously in the neck at about 20 weeks of age and were challenged with MG near 28 weeks of age, when they were in peak egg production. Various challenge schemes with infectious bronchitis virus were used at the time of MG challenge to increase the reduction in egg production. MG bacterins afforded protection against moderate drops in egg production in at least three of the studies, where the unvaccinated challenged control hens exhibited reduced egg production.
Animals↗
Prophylactic efficacy of a Marek's disease vaccine in broiler and replacement layer chickens.
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Abdomen↗
Obesity and hepatic rupture in caged layer chickens--environmental problem.
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Animals↗
Effect of ochratoxin A on Salmonella typhimurium-challenged layer chickens.
Eleven-day-old chickens received 10(8) colony-forming units Salmonella typhimurium orally for 2 consecutive days. The next day, the 13-day-old chickens were given a high dose of ochratoxin A (3 mg/kg) orally. The number of S. typhimurium in both the duodenal and cecal contents of chickens administered with high doses of ochratoxin A increased significantly when compared with control birds. Ochratoxin A was shown to be one of numerous factors that affect the susceptibility of chickens to salmonellae colonization.
Administration, Oral↗
Formation of neuroblastic layers in chicken retinospheroids: the fibre layer of Chievitz secludes AChE-positive cells from mitotic cells.
The significance of the classical subdivision of the retinal primitive neuroepithelium into an outer and an inner neuroblastic layer by the transient fibre layer of Chievitz (LOC) is little understood. We examine here the formation of neuroblastic layers by regenerating fully laminated retinospheroids from dissociated cells of the embryonic chick eye margin in rotary culture. By tracing cellular processes with the fibre-specific F11-antibody in retinospheroids, we occasionally find, in addition to an outer and an inner plexiform layer, a cell-free F11-positive LOC homologue, subdividing the inner nuclear layer. Moreover, we demonstrate that the LOC precisely separates postmitotic AChE-positive cells of the inner retina from an AChE-negative outer part holding all BrdU-labelled mitotic cells. These in vitro data suggest that the inner neuroblastic layer is exclusively composed of AChE-positive cells, thus representing a primary differentiation zone of the retina.
Acetylcholinesterase↗
Correlation between the usage volume of veterinary therapeutic antimicrobials and resistance in Escherichia coli isolated from the feces of food-producing animals in Japan.
We compared the overall usage of veterinary therapeutic antimicrobials in Japan to the proportion of antimicrobial-resistant. Escherichia coli isolated from the feces of apparently healthy food-producing animals in 2001. The annual sales volume of veterinary antimicrobials, which is published and accumulated information, was subdivided according to the target animal species (cattle, pigs, broiler chickens, and layer chickens). The antimicrobial susceptibility of the isolates was examined against 7 classes of 11 antimicrobials. The rates of antimicrobial resistance among the isolates were found to correlate significantly with the usage of antimicrobial agents in cattle, pigs, and broiler and layer chickens. Therefore, the overall usage of veterinary antimicrobials appears to contribute to the appearance of antimicrobial resistance in E. coli isolates from apparently healthy food-producing animals.
Animals↗
Contribution of lipoprotein lipase to differences in fatness between broiler and layer-strain chickens.
The growth of abdominal fat in chickens from broiler and layer-strains up to 10 weeks of age was measured and compared with changes in plasma very low density lipoprotein (VLDL) concentration and tissue lipoprotein lipase activities. The growth of abdominal fat in broilers was much more rapid than in layer-strain chickens. Plasma VLDL concentrations in the two strains were similar up to 5 weeks of age but thereafter concentrations tended to be higher in broilers. Plasma VLDL concentrations in both strains were much lower than those necessary for maximum lipoprotein lipase activity. The lipoprotein lipase activity of abdominal fat increased much more rapidly in broilers than in layer-strain chickens. In both strains the pattern of its increase relative to body weight was similar to that of abdominal fat. Differences in the lipoprotein lipase activity of abdominal fat between strains were attributed to differences in both activity/adipocyte and number of adipocytes. They were reduced or abolished if activity was expressed relative to tissue weight, or to its content of DNA or protein. The results strongly suggest that the greater lipoprotein lipase activity of the abdominal fat pad in broilers is an important factor in its rapid growth.
Adipose Tissue↗
Phosphoproteins of the chicken eggshell calcified layer.
The chicken eggshell matrix is a complex mixture of proteins and proteoglycans. It also contains phosphoproteins that are thought to affect mineralization of the matrix. Several of the matrix phosphoproteins, such as the major component osteopontin, have already been identified as phosphoproteins in other tissues, but the phosphorylation status of the eggshell matrix forms was unknown. The phosphopeptides, obtained after cleavage of the matrix proteins with several different cleavage methods, were enriched by anion-exchange chromatography and reversible binding to titanium oxide and identified by LC-MS(n) or pseudo-MS(n) analysis following neutral loss scanning. Altogether we identified 39 phosphorylated matrix proteins, 22 of which were not known to be phosphorylated before. Eight of the proteins were identified as eggshell matrix components for the first time. Together these proteins contained more than 150 different phosphorylation sites, 103 of which were determined with high confidence. Among the major phosphorylated proteins of the chicken eggshell matrix were osteopontin and the eggshell-specific proteins ovocleidin-17, ovocleidin-116, and ovocalyxin-32.
Amino Acid Sequence↗
The structure of a new phospholipid from the koilin-glandular layer of chicken gizzard.
A new phospholipid (Mr = 653; C32H64NO10P; [alpha]22D: - 24) was isolated from the keratinoidal layer of chicken gizzard. After acid hydrolysis the following products were identified: a C22-saturated aldehyde, sn-glycerol 3-phosphate, ethanolamine and D(-)-ribose. The substance is stable to alkali, it has saturated character, and after hydrolysis with CH3OH/HCI, yields only C22-dimethyl acetal. It contains a free NH2 group, and methylation produces 2,3,4-tri-O-methyl-D-ribose. The probable structure of the isolated phospholipid is proposed as 1,2-O-do-cosylidene-sn-glycero-3-phospho-(1 inch-ribosyl)-ethanolamine.
Animals↗
The synthesis of a new phospholipid from the koilin glandular layer of chicken gizzard.
In a previous publication, a new phospholipid was isolated from the keratinoidal layer of chicken gizzard, and on the basis of chemical, spectrometric (IR, NMR, UV) tests and mass analysis, the probable structure of the isolated phospholipid was proposed as 1,2-O-docosylidene-sn-glycero-3-phospho(1'-ribosyl)-ethanolamine (IX). In this paper, on the basis of probable structure, a new phospholipid was synthetized.
Animals↗
Outbreak of comb necrosis in layer breeder chickens.
Comb necrosis with leg weakness was seen in 41-day-old female layer breeder chickens. This disease occurred in three flocks at a breeder farm, but not in other flocks of growing chickens and broiler breeder hens at the same farm. The disease started in 35-day-old chicks in three flocks. The morbidity of comb necrosis was 10% and that of leg weakness was 3%. Characteristic gross lesions of affected chickens were swelling and necrosis of the whole comb. Histologically, liquefactive necrosis of epidermal epithelial cells with hyperplasia, vesicle formation in the epidermis, congestion, and hemorrhages with fibrinous thrombi of underlying dermis in the comb were noted. In mature comb lesions, the epidermis showed eosinophilic necrosis (scab formation). In the livers, multiple fibrinous thrombi were present in the sinusoids and there was necrosis of hepatic cells. Staphylococcus aureus and Pasturella spp. were isolated from comb lesions. There were no significant lesions causing leg weakness.
Animals↗
Growth of fiber types and apparent fiber number in skeletal muscle of broiler- and layer-type chickens.
Proportions of myofiber types, radial growth (diameter) of myofibers and apparent myofiber number were measured at the midsection of the sartorius muscle of broiler- and layer-type chickens. Broiler birds grew mor rapidly than layer birds so that in comparisons at equal age, broilers had heavier body and muscle weights, larger diameter type I and II myofibers and greater apparent myofiber number. The proportion of type II red myofibers decreased and that of type II white myofibers increased during growth. These changes occurred at a younger age in broiler-type birds. At equal body weights, however, broiler- and layer-type birds had similar proportions of the various myofiber types, which indicates that development of myofiber types is affected by functional demands on skeletal muscle related to increasing body weight. At equal body weights, broilers had larger diameter type II myofibers than layers and had a more rapid rate of type II myofiber radial hypertrophy during growth. In contrast, layer-type birds had larger type I myofibers than did broilers and the rate of radial growth was similar between breeds. Apparent myofiber number per unit of body weight increased during growth at a similar rate in the two types of birds but broilers had greater numbers of myofibers. It was concluded that more rapid growth and greater muscularity of broiler-type birds are caused by more rapid myofiber hypertrophy and the presence of more myofibers. It is suggested that selection for growth and muscularity favors factors that promote selective radial hypertrophy of type II myofibers as seen in broiler-type chickens.
Animals↗
Effect of genotype-nutrition interaction on growth and somatotropic gene expression in the chicken.
The neuroendocrine system integrates genotype with external factors such as nutrition to regulate animal growth. To investigate the role of somatotropic axis in the interaction of genotype and nutrition, two series of experiments were conducted using broiler and layer chickens as a model. In the first experiment, both strains of chickens were raised on their respective standard diets and the mRNA expressions of somatotropic genes were investigated on day 5 (D5), D21, and D42 after hatching as composites of genotype and nutrition. The hypothalamic somatostatin (SS) and pituitary growth hormone (GH) mRNA expression as well as the plasma GH levels were higher in layer chickens while the opposite was true for hepatic GH receptor (GHR) mRNA. Regulation of GHR mRNA expression was found to be tissue-specific. Hepatic GHR mRNA content increased with age whereas in the muscle, the peak levels of expression were observed at D5 with significantly higher abundance ratio in the layer. To evaluate genotype-diet interaction on growth and the patterns of gene expression of both layer and broiler chickens, layers were fed broiler diet and vice versa from D1 to 42 in the second experiment. The D42 body weight of layer chickens increased by 35% when fed with broiler diet, whereas that of broiler chickens decreased by 51% when fed with layer food. The diet exchange completely reversed the patterns of hypothalamic SS and pituitary GH mRNA expression and the strain differences vanished when the comparison was made on the same diet basis. The hepatic GHR mRNA decreased by 46.1% in broilers fed with layer food, but increased by 45.6% in the layer fed with broiler diet. The strain differences were diminished but did not completely disappear on the same diet basis for hepatic GH receptor mRNA. In contrast, however, the muscle GHR mRNA expression was not affected by diet exchange and thus, was more genotype-specific. The results suggest that genes of the somatotropic axis respond to nutrition differently at the level of transcription.
Aging↗
Selecting for efficiency of egg production using food-consumption records in layer-type chickens.
1. The purpose of the experiment was to evaluate the use of food consumption records in selection to improve layer-type chickens. 2. Twelve subpopulations of Leghorns, including 5878 tested birds, were used in a selection experiment which lasted 5 generations. Four were selected using an index (I1) that combined information on body weight (BW), egg-mass output (EM), and individual food-consumption records (FC). Four were selected using an index (I2) that combined information just on BW and EM. The remaining 4 served as controls, with selection differentials set to zero in each generation. 3. Differences between the selected groups, control-corrected each generation, measured the "food-record effect". 4. Including food-consumption records in the selection criterion resulted in increased body weight (7%), reduction in food consumption (6 to 9%), increase in food efficiency (egg mass/food consumption) (2 to 5%), and increase in income over food costs (10%), relative to selection not involving food records.
Animals↗