Efficiency and physiological safety of peas in the diets for hens (Gallus gallus L.) of the parent flock during the late laying period

Feeds are accounted for ca. 70 % of the commercial production costs of eggs and poultry meat. The use of other legumes (lupine, peas, horse beans, vetch) can lower the feed costs. However, the antinutritive factors of the legumes should be taken into account in the receipt formulation, especially in diets for pedigree flocks. Earlier we have proven physiological safety and effectiveness of the inclusion of 15 % of lupine in diets for layer parental flock. The substitution of peas for soybeans and lupine as the dietary protein source can further lower the costs of finisher diets for broilers and post-peak diets for layers where reduced protein levels are required. In the study presented we found efficient the substitution of peas (5 and 10 %) for soybean meal and sunflower cake in diets for parental flock of cage-housed layer chicken (cross SP 78, 30 birds per treatment) at the end of prolonged productive period (54-71 weeks of age). Control treatment 1 was fed the complete mash compound feed with soybeans as protein source; in diets for treatments 2, 3, and 4 the soybeans were increasingly substituted by peas (5, 10, and 15 % of total diet, respectively). After the artificial insemination 100 eggs from each treatment was taken since 70 weeks of age and incubated in DANKI incubator (Belgium) in constant regime. The temperature was set at 37.7 °С during 1-18 days of incubation and 37.2 °С during 18-21 days and controlled with the accuracy 0.1 °С; the relative humidity during these periods was 52-53 and 52-75 %, respectively. Mortality level, egg production, feed conversion ratios (per 10 eggs and per 1 kg of eggs laid), egg fertility and hatchability were recorded. The concentrations of vitamins and caroteniods in liver, chemical composition of liver, tibial concentrations of calcium and phosphorus were determined according to standard methods. The effects of the antinutritive factors were assessed via the histological study of the liver (at 71 weeks of age, n = 12); the samples were taken in 1 hour after the euthanasia from the similar liver part (lateral side of the right lobe) and fixed in 10 % neutral aqueous formalin. It was found that the inclusion of 5 and 10 % of peas into the diets of parental layer flock increased the intensity of lay by 2.38 and 4.97 % in compare to control, respectively, output of egg mass per hen housed by 3.78 and 12.23 %; the percentage of infertile eggs in these treatments was lower in compare to control. The histological study of liver revealed that 15 % of peas can launch the cytotoxic effect on the hepatic structures and induce the hepatic steatosis. This effect should be taken into account in the receipt formulations. It could be also concluded that peas can be included into the diets without preliminary thermal treatment; the antinutritive effects of pectin, trypsin inhibitors and proteases, tannins could be alleviated via the additional supplementation of the diets with exogenous enzymes, organic acids, and hepatoprotective agents.