The objective of the present study was to evaluate the effects of different levels of concentrate on the productive response of grazing dairy cattle and to determine voluntary forage intake. The experiment was carried out in a 4×4 Latin square design repeated three times, in which different inclusion levels of experimental concentrate were evaluated (EC) vs commercial concentrate (CC). The treatments were as follows: EC1= 7.12 kg DM of EC + grazing, EC2=6.23 kg DM of EC+ grazing, EC3=5.34 kg DM of EC+ grazing, CC=7.12 DM kg of a commonly used commercial concentrate (CC), and free-access grazing. The voluntary intake was determinate throw n-alkanes technique. The variables evaluated in cattle were milk output, live weight, and body condition; milk samples were also taken to determine protein and fat contents. Net herbage accumulation (NHA), forage height, neutral detergent fiber (NDF), acid detergent fiber (ADF), digestibility of organic matter (DIVMO), and metabolizable energy (ME) of pasture grasses were evaluated in addition to voluntary intake and production costs. Significant differences in crude protein content were found between the evaluation periods but were not found for NDF, ADF, DIVMO, NHA, and ME. Significant differences were not found in voluntary intake but were present in total intake. The evaluated treatments did not differ with respect to animal response. Finally, significant differences were found in milk output. Greater milk production was obtained in treatments 1 and 2 (14.92 and 14.50 kg/day/animal, respectively.

Objective: Carry out an exploratory evaluation of sheep and goats grazing in a temperate pasture invaded by Senecio inaequidens, as a means of biological control of weeds in small-scale dairy systems (SSDS). Methodology: Crude protein (CP), neutral detergent fibre (NDF), and acid detergent fibre (ADF) were determined on pasture and Senecio samples. The effect of grazing by sheep and goats on the pasture was assessed by means of the height, density and soil cover of Senecio, and also sward height; and the live weight of the animals, daily weight gain and body condition score were recorded. Statistical analysis was by a 2x2 factorial design, with species (sheep or goat) and two grazing intensities at 28.3 or 50.3 m2/animal per day. Results: height, coverage and density of Senecio did not show significant differences (P>0.05), neither did sward height. The chemical composition of the pasture did not show statistically significant differences for the assessed periods either. Animal weight, body condition and daily weight gain did not show significant differences among the evaluated treatments (P>0.05). Implications: This is the first report evaluating sheep and goat grazing to control of Senecio invasion in temperate pasture in central Mexico. In addition, knowing the chemical quality of Senecio will allow decisions to be made for supplementation in grazing systems with sheep or goats. Conclusions: The grazing of sheep and goats reduced the number of Senecio plants in the assessed pasture, which indicates the possibility of controlling this weed by grazing sheep or goats over longer-term grazing.