Abreu Filho et al., 2024. Revista Brasileira de Zootecnia, 53:e20230132.

The objective of this study was to examine the effect of the increasing levels of inclusion of palm kernel cake (PKC) in the diet on the performance of feedlot heifers. Forty-eight Nelore heifers with an initial weight of 274 ± 4.58 kg, at 24 months of age, were confined for 98 days in a feedlot. The animals were allocated to the four treatments in a completely randomized design. Treatments consisted of PKC levels of 0 (control), 10, 20, and 30% in the total dry matter of the diet. The roughage:concentrate ratio in the diets was 30:70. Ether extract intake increased, whereas the intakes of non-fiber carbohydrates and total digestible nutrients decreased with the inclusion of PKC. The apparent digestibility of all nutrients decreased, as well as the amounts of nitrogen digested and retained. Microbial protein synthesis and its efficiency also declined. The inclusion of up to 20% PKC increased feeding time and reduced rumination time of heifers. Intake and rumination efficiencies decreased with the inclusion of PKC in the diet. Final weight and average daily gain did not change, but feed efficiency increased with the inclusion of PKC. The inclusion of up to 30% PKC in the diet of feedlot heifers is recommended.