S. Chobanova1, D. Penkov2*

1Department of Morphology, Physiology and Nutrition, Section Animal Nutrition, Faculty of Agriculture, Trakia University, 6000 Stara Zagora, Bulgaria
2Department of Animal Sciences, Faculty of Agronomy, Agricultural University, 12 D. Mendeleev Str., 4000 Plovdiv, Bulgaria

(Manuscript received 28 May 2021; accepted for publication 30 June 2021)

Abstract. The aim of the study is to compare the net utilization of energy and protein in the eco-technical chain „feed-meat“ when replacing part of the soybean meal with high-protein sunflower meal in broiler fattening. One control and 3 experimental groups, 4-phases fattening with isoenergetic and isoprotein combined fodders. Main protein source in the fodders for the control group is soybean meal. Replacement with sunflower meal: First experimental group: Starter – 5%, Grower – 8%, Finisher 1 – 10% and Finisher 2 – 10%; Second experimental group: 15, 18, 25 and 25%, respectively; Third experimental group: 34.25, 27.27, 27.27 and 26%, respectively. Clarcs of energy distribution/protein transformation (CED/CPT) are the ratio between accumulated gross energy/crude protein in breast and thigh muscles and consumed metabolic energy/crude protein throughout life. The following results were established: CED “fodder – breast+thigh muscles”: Control – 0.2430, first experimental group – 0.2394, second experimental group – 0.2505, third experimental group – 0.2334; CPT – 0.6080, 0.5050, 0.5280 and 0.5490, respectively.