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In Mexico the ant Liometopum apiculatum is an important insect nutritionally, economically and ecologically. Their larvae (“escamoles”) contain proteins, lipids, vitamins and minerals, the concentrations of which may be related with the type of vegetation where the ant forages. The objective of this study was to evaluate the content of macro and micro nutrients of L. apiculatum larvae collected in three types of vegetation in north-central Mexico. We determined content of moisture, crude protein, total lipids, crude fiber, ash, and nitrogen-free extract. The amino acids were analyzed by cationic Exchange chromatography with acid hydrolysis and fatty acids by gas chromatography and solvent extraction with sodium methoxide. The effect of vegetation type on nutrient content was determined with an ANOVA and Sheffe comparison of means (P

Feed efficiency was measured in thirty Pelibuey noncastrated male lambs using the residual feed intake (RFI) and residual intake and gain (RIG). The lambs were fattened for 92 d and then slaughtered, with the aim of identifying the interplay between feed efficiency indices (FEIs) and performance, rumen fermentation parameters, carcass characteristics and meat quality traits from the 15 intermediate and most extreme lambs for each FEI. The mean values of the classes were -0.09, 0.00, and 0.09 kg DM/d for low, medium and high RFI, respectively. The RIG indicators were 2.6, -0.1, and -2.7, for high, medium and low, respectively. The lambs with high-RIG had a higher (P ≤ 0.05) average daily gain and improved feed conversion. Lambs with low-RFI and high-RIG had higher (P 0.05) values of meat cooking loss. Efficient lambs had improved feed utilization without affecting the carcass characteristics or meat quality (except for cooking loss).