Japanese Quail Hens Research Articles

Morphological and ultrastructural aspects of the activation of avian medullary bone osteoclasts by parathyroid hormone.

The activation of physiologically inactive medullary bone osteoclasts by parathyroid hormone (PTH) was examined using light and electron microscopy and histomorphometric methods. Medullary bone osteoclasts are functionally inactive during the avian egg-laying cycle when an egg shell is not being calcified in the shell gland. Japanese quail hens were given 0.5 IU/g PTH and the medullary bone osteoclasts were examined up to 90 min later. Administration of PTH results in rapid changes in osteoclast morphology and ultrastructure. Within 10 min ectoplasmic regions containing condensed-appearing material are evident in areas of the cell adjacent to bone surfaces. In tannic acid-fixed specimens, these ectoplasmic regions contain bundles of filaments extending perpendicularly from the osteoclast plasma membrane into the cytoplasm. It is in these areas that ruffled border development is initiated. Even at 10 min after PTH administration, mineral crystals are seen between the developing cell surface invaginations and folds. By 15 min after PTH administration, ruffled borders have appeared next to bone surfaces. The rapid development of ruffled borders on medullary bone osteoclasts after PTH is confirmed by electron microscope histomorphometry. By 30 min after PTH administration, ruffled borders are well developed and large endocytic vacuoles are beginning to appear in the osteoclast cytoplasm. Light microscope histomorphometric measurements indicate that osteoclasts are also increasing in size and spreading along bone surfaces with time after PTH administration. This study provides a morphologic and ultrastructural description of osteoclast activation by PTH. The results indicate that osteoclasts may effect rapid changes in bone resorption and mineral metabolism due to exogenous PTH in hens.

Lead-Induced Egg Production Decrease in Leghorn and Japanese Quail Hens

A study was conducted to compare the response of chicken hens and Japanese quail hens to various levels of dietary lead as plumbus acetate. Egg production was decreased significantly in quail receiving 1 mg lead/kg of diet from day of hatch, and 10 mg lead/kg diet was required to suppress egg production when the metal was given to the quail hens after they had reached sexual maturity. In chicken hens given lead after they had attained approximately 80% hen-day production, a comparable decline in egg production was seen in hens consuming at least 200 mg lead/kg of diet. Total plasma calcium in quail hens was reduced significantly by 10 mg lead/kg of diet, but total plasma calcium in chicken hens was not reduced with levels of less than 200 mg lead/kg of diet. There was no correlation between blood calcium level and decreased egg production in chicken hens consuming dietary lead at levels less than 200 mg/kg diet, suggesting that lead influences egg production in birds through mechanisms that may not be dependent entirely upon calcium metabolism. Removal of lead from the diets of quail was associated with significant increases in egg production and total plasma calcium, but removal of lead from the diets of chicken hens did hot cause any increase in total plasma calcium or increase egg production in treated hens. However, hens consuming the highest level of dietary lead (400 mg/kg) did increase significantly their rate of egg production, but this was attributed to recovery from a lead-induced molt. Results from this study indicated that the Japanese quail hen was more sensitive to the reproductive inhibitory effects of lead than the chicken hen.

Influence of dietary calcium selenium and methylmercury on eggshell thickness in Japanese quail.

A high Ca, semi-purified diet promoted greater egg production with thicker shells in Japanese quail hens. 7 ppm of dietary Se depressed egg weights with no effect on eggshell thickness. The addition of 20 ppm of MHg to either a low or high Ca diet containing Se depressed both egg production and eggshell thickness. Se residues of liver, kidney, and brain in Se-MHg fed quail were significantly higher than in Se treated quail, probably reflecting the ability of Se to bind with Hg. CA, an enzyme required for the formation of the carbonate radical of Ca carbonate in eggshells, was not reduced in the Se-MHg treated Japanese quail hens' blood or oviducts.

Prostaglandin levels in avian blood and reproductive organs.

A radioimmunoassay with a sensitivity of 5 pg/assay tube was established to measure prostaglandins E, F, and A in avian plasma and tissues. Compared to plasma values when no egg is present in the uterus (shell gland), PGE but not PGF or PGA levels were significantly higher in hens in which an egg was present (P<0.001). However, in the various segments of the oviduct as well as in the lung, PGF levels were 2–8 times higher than PGE levels. In the plasma of laying Japanese quail hens, both PGE and PGF (but not PGA) levels were significantly higher than in birds that ceased to lay. Relatively high PGE concentrations were found in turkey hens during the day (855 pg/ml), and these increased significantly in the evening (1310 pg/ml). Prostaglandin levels in the plasma of roosters were generally lower than in hen plasma. Similarly, concentrations in the testes were considerably lower than those found in ovaries. It is suggested that, in the domestic hen, E prostaglandins are involved not only in promoting oviposition (as previously proposed) but also in mobilizing calcium from skeletal stores during the hours of intensive shell formation.