Standardised Ileal Amino Acid Digestibility in Field Pea Seeds of Two Cultivars Differing in Flower Colour for Broiler Chickens: Effects of Bird Age and Microbial Protease.

Witold Szczurek,Sylwester Świątkiewicz

doi:10.3390/ani10112099

Abstract

Simple SummaryThe extent to which field peas can replace soybean meal in diets for broiler chickens is limited, and one of the reasons for this may be a lack of careful consideration given to the age-related amino acid availability differences in feed formulations. As the digestibility of amino acids in feeds for poultry is a sensitive gauge of their bioavailability, this study has determined and compared standardised ileal amino acid digestibility estimates for whole (raw) seeds of white- and coloured-flowered pea cultivars fed to young and older chickens (14 or 28 days old) in the presence or absence of exogenous protease in their diet. The results demonstrate that when a digestible amino acid system is used, the coefficients of essential amino acids determined at 14 days of age in low-tannin white-flowered peas are not applicable to the formulation of grower-type feed mixtures containing seeds of coloured-flowered cultivars. The increased digestibility of nutritionally essential amino acids in white-flowered pea fed to bids at both ages and in coloured-flowered pea fed to chickens aged 28 days can be expected from protease supplementation. These results contribute to improved use of peas as an alternative to soybean meal vegetable protein sources in diets for broiler chickens.This study aimed to determine and compare standardised ileal digestibility (SID) coefficients of amino acids (AA) in raw seeds of the white-(WF) and the coloured-flowered (CF) field pea cultivar as sole sources of AA in the diets fed to broiler chickens aged 14 or 28 days. An additional purpose was to check the influence of exogenous protease added to pea-based assay diets on AA SID in birds at both ages. Each assay diet was offered to six replicate pens. On both sampling days, the contents from the lower half of the ileum were collected for determination of the apparent digestibility values. The SID coefficients were calculated using ileal endogenous AA losses determined from birds fed an N-free diet. Results indicated a substantial advantage of WF pea over CF pea as a source of digestible Lys, Met, Cys, His, Ile, Leu, Phe, Val, Asp and Glu for 14-day-old chickens. With the exception of methionine and cysteine, there was no significant difference between these two cultivars in the SID values of AA in 28-day-old birds. The protease increased SID of nutritionally essential AA from WF pea-based diet at both ages, and from CF pea-based diet in chickens aged 28 days. In conclusion, the SID coefficients of indispensable AA determined at 14 days of age in low-tannin WF peas are not applicable to the formulation of grower-type feeds containing seeds of CF cultivars.

Highlights

Since the soybean meal (SBM) is currently a primary source of protein and indispensable amino acids (AA) in swine and poultry compound feeds, the intensive production of monogastric meats and eggs in the European Union (EU) countries is highly dependent on imported soybean
The standardised ileal digestibility (SID) coefficients of indispensable AA determined at 14 days of age in low-tannin white flowers (WF) peas are not applicable to the formulation of grower-type feeds containing seeds of CF cultivars
The present results suggest that when the SID coefficients are taken into account, with the exception of methionine and cysteine, there is no significant difference between these two cultivars of pea in the digestibility of AA

Summary

Introduction

Since the soybean meal (SBM) is currently a primary source of protein and indispensable amino acids (AA) in swine and poultry compound feeds, the intensive production of monogastric meats and eggs in the European Union (EU) countries is highly dependent on imported soybean. According to FAOSTAT data, in the EU, and in Europe as a whole, field pea (Pisum sativum L.) is the most widely cultivated grain legume species to produce dry seeds used as both animal feed and human food [3]. The average protein content of Pisum sativum seeds is reported to be 24% of dry matter weight with a wide variation between cultivated varieties, growing locations and harvest year. Pea protein is high in some indispensable AA, such as lysine, arginine and leucine, though low in sulphur-containing amino acids [4,5,6]. It has been shown that partial substitution of dietary SBM with a high amount of raw peas (200–500 g/kg) may have a negative impact on broiler chicken performance [7,8,9]

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