Faba beans (Vicia faba L.) and field peas (Pisum sativum L.) as feedstuffs for broiler chicken: Precaecal protein and amino acid digestibility

Summary

Especially in areas with suboptimal conditions for the cultivation of soybeans, homegrown grain legumes, like faba beans and field peas, are very important protein feedstuffs for monogastric animals, like swine and poultry, in organic farming. Homegrown grain legumes contribute to the circular ecology of organic farms and add to the supply of essential amino acids to the diet.
However, their value is not only determined by the crude protein content and amino acid profile but also by the bioavailability of crude protein and amino acids. Since only precaecally absorbed amino acids are potentially available in the metabolism, the precaecal digestibility of the crude protein and the amino acids can give a hint on their bioavailability.
The aim of the study was to determine the precaecal digestibility of each a tannin-free frequently used faba bean (Vicia faba L.) and field pea (Pisum sativum L.) variety in young broiler chicken.
The precaecal crude protein and amino acid digestibility of the single feedstuffs was determined in 21-day old broiler chickens using a linear regression approach.
Crude nutrient analyses were conducted using VDLUFA methods (crude protein with N*6.25), amino acid contents were analysed with HPLC modified Cohen and Michaud [3], and TiO2 contents were determined photometrically.
Diets containing three different levels (30, 50, and 70%) of the test feedstuff in exchange for maize starch (40, 20, 0%) and a defined amount of the marker TiO2 were fed to birds for one week until they reached 21 days of age. Each diet was fed to six groups of 18 broiler chicken. The test feedstuff was the sole source of additional crude protein and amino acids. The birds were killed by asphyxiation with CO2 and the digesta was gently flushed from the terminal two thirds of the ileal section between Meckel’s diverticulum and 2 cm prior to the ileo-colonic junction with distilled water. The intake of the crude protein and amino acids was related to the precaecally digested amount of the crude protein and amino acids by linear regression analysis. The slope of the regression is used as predictor for the precaecal digestibility coefficient.
Bird performance was comparable to previous studies and high inclusion rates of faba beans and fiel peas did not lead to feed refusal or health problems. The relation between ingested and precaecally digested amounts of crude protein and all amino acids was linear.
The standardized precaecal digestibility of the amino acids was comparable or higher compared to literature results. Crude protein digestibility reached 84% and 81% for the faba beans and the field peas, respectively.
The digestibility of the crude protein and amino acids of organic field peas and faba beans is good. Thus, organic field peas and faba beans are suitable feedstuffs for young broiler chickens.