Figure 1
Experimental design of the study. Both Group A and Group B consisted of 30 growing-fattening beef cattle each (illustrated as circles within boxes, with boxes representing pens). During the first residual feed intake (RFI) test (0–70 days), Group A was fed ad libitum, while Group B underwent feed restriction. In both groups, 6 animals with the lowest and 6 with the highest RFI values were identified and sampled for blood (depicted as 24 black circles during the first RFI test). Following a 1-week transition period, the treatments were switched for the second RFI test (78–148 days): Group A underwent feed restriction, and Group B was fed ad libitum. Only the 24 cattle with the most extreme RFI values, sampled during the first RFI test, were resampled during the second RFI test (depicted as 24 black circles during the second RFI test). In Group A, the same RFI grouping established during ad libitum conditions (highest [H] and lowest [L] RFI) was maintained during feed restriction. In contrast, due to minimal RFI variation during feed restriction, the RFI ranking in group B (ranking number within black circles), as established during ad libitum conditions (second RFI test), was retained during feed restriction as well. For both groups and RFI tests, the retained RFI values were those obtained in ad-libitum conditions.
