Digestibility of phosphorus in laying hens fed a wheat-maize-soyabean diet and the excreta phosphorus fractions

Abstract

Availability of phytate phosphorus (P) was determined in ISA Brown hens 21 and 47 weeks old, fed a wheat-maize-soyabean diet, without a phytase supplement. The diet contained total and phytate P at 4.99 and 1.58 g/kg, respectively. The average body weight and hen-day egg production were 1.56 kg and 0.52, and 1.92 kg and 1.00 for younger and older hens, respectively. Phytate in the feed and faeces was determined by a capillary isotachophoretic method. Availability of phytate P and proportion of dietary Ca retained was non-signifi cantly higher in older hens than in younger ones (47.3 and 56.7% vs 38.7 and 44.4%, respectively). Amount of P retained was similar in both groups (199 and 194 mg/day in younger and older birds, respectively). Amount of Ca retained was signifi cantly higher in older than in younger hens (2.87 and 1.69 g/day, respectively; P<0.05). Dry matter of excreta of 47-week-old hens contained signifi cantly (P<0.05) more total and phosphate P than excreta of 21-week-old hens (14.8 and 8.9 mg/g vs 12.3 and 5.9 mg/g dry matter, respectively). Phytate P represented 30.9% of excreta P in younger and 23.0% in older hens. Corresponding proportions of phosphate P were 48.0 and 60.1%. Differences between younger and older hens in proportions of P fractions were statistically signifi cant (P<0.05). Excreta of 21-week-old hens and those of 47-week-old hens contained 78.1 and 63.0 mg of Ca/g dry matter, respectively (P<0.05). Thus, the age and different egg production signifi cantly affect retention of Ca and excreta composition in laying hens. The effect of age on phytate availability was less pronounced.

Intestinal and total tract phytate digestibility and phytase activity in the digestive tract of hens fed a wheat-maize-soyabean diet

“…The total tract digestibility of phytate P (33 and 35% in this study) is in agreement with values reported by Scheideler and Sell (1987), Carlos and Edwards (1998) and Marounek et al (2008b). In laying hens fed on a maize-soyabean diet, Scheideler and Sell (1987) reported a phytate P digestibility of 46.6% at 34 weeks of age, which declined at 50 and 72 weeks of age.…”

“…It has been shown in the excreta of laying hens on a maize-soyabean diet (Marounek et al, 2008a), broiler chickens (Leytem et al, 2008b), and in other animal species (for references see Marounek et al, 2008b). As for the total P concentration in the excreta, similar values were reported in laying hens on a wheat-maize-soyabean diet by Zobac et al (1998).…”

“…In laying hens on a similar diet, Carlos and Edwards (1998) found that 43.0% of the phytate P was utilized. In laying hens on a wheat-maize-soyabean diet Marounek et al (2008b) reported a phytate P digestibility of 38.7% in 21-week-old hens and 47.3% in 47-weekold hens. In laying hens on a maize-soyabean diet, the phytate P digestibility was 24% in hens 20-week-old and 53% in 47-week-old hens (Marounek et al, 2008a).…”

“…Poultry are capable of utilizing part of the dietary phytate P without a phytase supplement. This has been shown both in broiler chickens (Mohammed et al, 1991;Edwards, 1993;Leske and Coon, 2002) and in laying hens (Scheideler and Sell, 1987;Leske and Coon, 1999;Marounek et al, 2008b). Although a considerable number of papers have been published in recent years dealing with supplemental exogenous phytases, only several authors attempted to elucidate the role of digestive tract phytase and identify the site of phytate P hydrolysis.…”

Effect of different phosphorus levels on the performance and egg quality of laying hens fed wheat- and maize-based diets

“…The shells were weighed after drying at 105°C. The feed was analysed as described previously (Marounek et al, 2008). Total P in the feed and in dried eggshells was determined using a vanadate-molybdate reagent after the ashing of dry samples at 550°C (AOAC procedure 965.17).…”