Nutrient retention and growth performance of chicks given low-phytate conventional or hull-less barleys

Abstract

1. The experimental barley samples included 4 hulled and one hull-less low-phytate barley cultivars and two commercial barley varieties as controls.

2. The diets were provided in meal form, with the experimental barley samples constituting the cereal source. Two additional treatments were added for each of the control varieties in which intermediate and recommended levels of phosphorus were provided.

3. A completely randomised design was used with 5 replicates of 5 chicks per treatment. The chicks were grown from 2 to 14 d of age with excreta collected over the subsequent 3 d.

4. Although total phosphorus levels were similar for all barley samples, there were large differences in their phytate content, which ranged from less than 0·5 to 13·8 g/kg. M2 955 hulled barley exhibited the lowest phytate and the highest phosphorus solubility.

5. There was a negative linear relationship between grain phytate and weight gain and with bone ash. The low-phytate hulled barleys M2 955 and the low-phytate hull-less barley (lpa1-1H) gave better feed conversion (8%) than controls. The hull-less low-phytate barley gave significantly higher total phosphorus (18%) and soluble phosphorus retention (23%) than the hull-less control. The low-phytate samples tended to give lower excreta phosphorus levels (total and soluble), but the effect was significant only for the hull-less samples. Amino acid retention was significantly higher for the low-phytate hull-less barley than the control (4%).

6. Overall, the results suggest that using low-phytate barley can result in similar growth while using less supplemental phosphorus, reducing waste phosphorus by more than 50%.

AcknowledgEments

The authors wish to acknowledge the contribution of Ms. Dee Culbert for general laboratory analysis and phytate, Mr. Peter Mills for amino acid analysis and Mr. Robert Gonda for chick care.