Phosphorus requirements of laying hens fed on wheat‐based diets

Abstract

1. Three experiments were carried out to determine the phosphorus (P) requirements of laying hens aged 34 to 58 weeks (experiment 1), 59 to 70 weeks (experiment 2) and 22 to 50 weeks (experiment 3) given diets containing wheat, sorghum and soyabean meals as the main ingredients. Dietary total P (Pt) varied between 3.2 and 7.3 g/kg (experiment 1), 3.2 and 4.6 g/kg (experiment 2) and 3.0 and 6.6 g/kg (experiment 3). Hens were housed at either 18 degrees or 30 degrees C (experiments 1 and 2) and uncontrolled temperature (experiment 3), and in experiment 2 diets were fed without or with a phytase supplement of 500 units/g. 2. Dietary Pt had no significant effect on production measures in any experiment. Increases in dietary Pt adversely influenced egg shell quality although uterine calcium (Ca), ATPase and carbonic anhydrase activities were unaffected. 3. A 3-d-feeding trial in experiment 1 gave maximum Pt retentions of 228 mg/d at 18 degrees C and 204 mg/d at 30 degrees C. These were obtained with diets containing, respectively, 4.6 and 6.0 g Pt/kg. 4. Plasma inorganic P (Pi) increased consistently with increases in dietary Pt at all temperatures but plasma total Ca, and tibia Ca and P, were unaffected. 5. The inclusion of the phytase supplement in diets containing 3.2 and 4.6 g Pt/kg had an adverse effect on egg production at both temperatures in experiment 2. 6. A dietary Pt concentration of 3.2 g/kg, providing a calculated 1.2 g available P (Pav)/kg, with a dietary phytase activity of less than 200 units/kg, satisfied the P requirements of the hens used in these studies. However, the data from experiment 3 suggest that the Pt requirement of some flocks fed on wheat-based diets may be lower than 3.2 g/kg.

The effect of phosphorus, phytase enzyme, and calcium on the performance of layers fed wheat-based diets

“…This experiment confirms the findings of Newkirk et al (1993), Jeroch and Peter (1994), and Usayran and Balnave (1995) that exogenous phytase does not have the same positive effects in wheat-based diets as it does in corn-based diets. Positive effects of enzyme on production in the final period do not appear to be on the release of phytate P, and enzyme addition produced none of the negative effects of excess P. Usayran and Balnave (1995), Gordon and Roland (1998) and Um and Paik (1999) have suggested that the effect of phytase enzyme is not only on P release.…”

“…Positive effects of enzyme on production in the final period do not appear to be on the release of phytate P, and enzyme addition produced none of the negative effects of excess P. Usayran and Balnave (1995), Gordon and Roland (1998) and Um and Paik (1999) have suggested that the effect of phytase enzyme is not only on P release. Newkirk et al (1993) described interactions between phytase and xylanase enzymes, suggesting that intestinal viscosity may influence the effect of phytase when wheat is fed.…”

“…Jeroch and Peter (1994) found that phytase in wheat-based diets did not influence performance. Usayran and Balnave (1995) found that phytase addition to wheatbased diets adversely affected egg production. The purpose of this paper is to further explore the effect of phytase and the interaction of exogenous phytase with Ca and AP levels.…”

Effect of dietary phosphorus level and supplemental phytase on performance of Hisex Brown laying hens and egg shell quality

“…Nys (1995), after Sauveur (1989, mentions that for a diet containing 300 units of plant origin phytase the amount of mineral phosphorus added to the diet can be reduced to 0.12%. Similar results were obtained by Usayran and Balnave (1995) who found that when a diet containing over 40% wheat and 200 U of plant origin phytase was used no insufficiency of phosphorus was observed even at 0.12% AP in the diet. In the experiments of these authors the addition of 500 U of microbial phytase to a diet containing 0.32 or 0.46% TP (0.12 or 0.24% AP, respectively) has a negative effect on laying rate and egg shell quality from hens consuming 125-128 g of feed with laying rate below 80%.…”

“…This assumption seems to confirm the results obtained by Keshavarz (1986) who found that, depending on P intake from the diet (540 -880 mg), the utilization of P ranged from 21.1 to 30.5%. According to Usayran and Balnave (1995), with daily intake of P between 352 and 837 mg, the utilization of this element ranged from 19 to 29% and was therefore similar to that observed by Keshavarz (1986).…”