Four experiments were conducted to evaluate the influence of eight shrub leaves on digestion, nitrogen retention and ruminal digestion characteristics by sheep. In general, in all experiments, only few variations in nutrient intake, nutrient digestion coefficients and N retention were observed between sheep fed diets containing M. sativa hay and sheep fed diets with different levels of shrubs. The same responses were detected in sheep rumen fermentation parameters and data for digestibility values: a, b and c values and effective degradability of dry matter, crude protein and neutral detergent fiber of individual forages. Even though, all shrub species contained high levels of crude protein, it seemed that plant secondary compounds in browse species affected their nutritional quality, reducing the nutrition of sheep fed diets with different levels of browse plants. However, native shrubs growing in semiarid regions of northeastern Mexico may have potential as an economical supplementary feed for sheep fed diets based on roughages of low nutritional quality.

Five experiments were carried out to evaluate the effects of the use of brewer's grain (BG) It is suggested that pigs may be feeding with 30% WBG diets in post-weaning periods and 30 or 45% during growing and finishing periods. In feedlot sheep, grow increments and digestion characteristics of lambs were similar among treatments. Lambs fed bicarbonate or monensin or bicarbonate and monensin combination had better performance characteristics than lambs on control diet, with bicarbonate or endogenous enzymes. In dairy cattle, the dry matter intake, milk production and acetate: propionate ratio were enhanced by bicarbonate or enzymes addition.

The aim of the study was to measure differences in nutritive content, over four seasons, of native grasses such as Aristida purpurea Nutt. var. longiseta (Steud.) Vasey, Bouteloua curtipendula (Gould et Kapadia), Bouteloua hirsuta Lag., Bouteloua trifida (Thurber), Chloris verticillata Nutt., Digitaria insularis (L.), Panicum halli (Vasey.), Setaria grisebachii (Fourn.), Setaria macrostachya (H.B.K), Tridens eragrostoides, Tridens muticus (Torr.) Wash., and cultivated Cenchrus ciliaris (L.) and Rhynchelytrum repens (Willd.) C. E. Hubb. that are used as forages for grazing ruminants. Cenchrus ciliaris was included as reference grass of good nutritional quality. Higher chemical content and EDDM and EDCP occurred during the wet seasons (summer and autumn). Because of their good nutritional quality, grasses such as Panicum hallii, Setaria grisebachii, Setaria macrostachya and Tridens eragrostoides can be considered good forages for ruminants.

Calcium, K, Mg, Na, P, Cu, Fe, Mn and Zn contents were determined, seasonally, during two consecutive years in leaves of native browse plants such as Castela texana T. & G. Rose (Rutaceae), Celtis pallida Torr. (Ulmaceae), Forestiera angustifolia Torr. (Oleaceae), Lantana macropoda Torr. (Verbenaceae) and Zanthoxylum fagara (L.) Sarg (Rutaceae) growing in rangelands at northeastern Mexico. All minerals, in all species, were significantly different among years, sites and seasons and interactions were also significant. In general, plants in Linares county site, that had the highest rainfall had higher mineral content followed by Los Ramones and China counties; Moreover, during summer all plants had higher mineral content followed by autumn, winter and spring. Regardless of spatio-temporal differences, all plant species had suitable levels of Ca, Mg, K, Cu, Fe and Mn to satisfy range domestic and wild ruminant requirements. Nonetheless, P, Na and Zn showed marginal inadequacies in some seasons throughout the year.