Effects of different short-term dietary phosphorus levels on egg specific gravity and blood phosphorus of hens

Effect of dietary calcium and phosphorus levels on ultra-filterable calcium and dialyzable phosphorus in the laying hen

Laying hens were fed diets containing combinations of 2.6 or 3.6% calcium and .45 or .75% total phosphorus. After receiving the diets for 2 wk, blood samples were collected during a 24-h period at 6-h intervals and total calcium, ultrafilterable calcium and dialyzable phosphorus was determined on blood plasma. Plasma total calcium was higher (P less than .05) in hens that received the diets containing the higher level of calcium (3.6%), but was not influenced by dietary phosphorus levels. Overall in the experiment, neither the dietary calcium nor phosphorus levels had significant effects on the plasma ultrafilterable calcium or dialyzable phosphorus. However, at 0600 and 1200 h, dialyzable phosphorus levels in plasma of hens fed the diet high in both calcium and phosphorus was significantly (P less than .05) greater than that in plasma from hens fed diets low in both calcium and phosphorus. The time that the blood sample was taken had a significant effect (P less than .05) on plasma total calcium, ultrafilterable calcium, and dialyzable phosphorus.

The relationship of dietary levels of phosphorus to the production of soft-shelled and shell-less eggs

The relationship among available levels of dietary phosphorus (.2, .3, and .4%) and the production of soft-shelled (SS) and shell-less (SL) eggs was investigated in 864 White Leghorns of a commercial strain. An 11-month performance profile included hen-day production of hard-shelled (HS), SS, and SL eggs, feed consumption, livability, egg weight, and specific gravity. Percent HS egg production and feed consumption were significantly lower and egg specific gravity was significantly higher among hens consuming the .2% available phosphorus diet when compared to hens consuming the .3 or .4% available phosphorus diets. The level of available phosphorus in this study did not affect significantly hen livability or the production of SS or SL eggs. Five hours (HS egg in uterus) or 15 hr (SL egg in uterus) prior to expected oviposition time, 1 ml of a 200 mM phosphate solution was injected into the brachial vein (i.v.) or the uterus (i.u.) of hens observed to lay consistently HS eggs. Injections i.v. did not alter expected oviposition time when either a HS or SL egg was in the uterus, but i.u. injections induced premature oviposition when a SL egg was in utero. The concentrations of inorganic phosphorus and total calcium in the plasma and uterine fluid of hens that laid a high or low incidence of SS + SL eggs were determined 5 hr after the egg entered the uterus. Uterine fluid inorganic phosphorus and total calcium and plasma inorganic phosphorus levels of the high and low incidence groups were not significantly different. However, plasma total calcium was significantly higher among high incidence SS + SL layers when compared to low incidence SS + SL layers at this time during the ovulatory cycle.

The influence of dietary phosphorus level on laying hen performance, egg shell quality, and various blood parameters

The influence of dietary phosphorus on hen performance and egg shell quality was investigated. Total dietary phosphorus levels of .17, .23, .30, .40, .50, .70, 1.50, and 2.30% were fed to four body weight groups of 23-week-old White Leghorn hens. Hens consuming the diets containing .17, .23, and .30% phosphorus, all from plant origin, consumed significantly (P less than or equal to .05) less feed, which resulted in poorer performance than hens fed diets supplemented with inorganic phosphorus. Addition of supplemental inorganic phosphorus at levels of .10 to .40% resulted in the best overall hen performance. Plasma phosphorus was directly related to dietary phosphorus level. Egg shell quality as measured by specific gravity was inversely related to dietary phosphorus levels above .50%.

Dietary and plasma phosphorus in hens with fatty liver syndrome

Plasma inorganic phosphorus was determined in two experiments in hens that had fatty liver syndrome. In Experiment 1, plasma inorganic phosphorus was determined in twelve strains of hens all fed the same diet. Plasma inorganic phosphorus immediately following oviposition was elevated in all strains. The two strains in the first experiment with the highest as well as the two strains with the lowest plasma inorganic phosphorus were used in the second experiment. Each of the four strains were subdivided into three groups of 60 hens each and fed a practical layer diet containing either .30, .75, or 1.40% total phosphorus and 3.4% calcium. Significant differences were found in plasma inorganic phosphorus between strains fed the three dietary phosphorus levels. Results indicated that plasma inorganic phosphorus is related to dietary phosphorus in hens with an elevated plasma inorganic phosphorus level associated with fatty liver syndrome.