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Objective: To evaluate the effect of different grassland renovation methods on the Lolium sp. productivity during rainy and dry seasons in the high tropic of the Nariño department. Materials and Methods: The essay was conducted between January and August, 2018. Two experiments were established in the Pasto and Sapuyes municipalities. An experimental design of complete randomized blocks was used, with five treatments and three replicas (T1: farmer's conventional management; T2: grassland renovator; T3: harrowing twice; T4: rigid chisel plow once, harrowing once and subsoiling once; T5: vibratory chisel plow once and harrowing once). The variables cover percentage, height, green forage and dry matter yield, were evaluated. For the statistical analysis, the software R V 3.5.1 was used. Variance analysis and Tukey's test were carried out for comparison among means (p < 0,05). Results: In the rainy season, in the Pasto locality, the variable plant height showed significant differences among treatments (p < 0,001). T5 showed the highest value (38 cm). In turn, significant differences were found in the green matter and dry matter yield among treatments, T3 being the one with the best performance (16,2 and 2,6 t ha-1, respectively). In the Sapuyes locality, T1 reached the best results for the variables cover percentage, plant height, green forage and dry matter yield (96,0 %; 67,5 cm; 34,2 t ha-1 and 4,19 t ha-1, respectively). In the dry season, in the Sapuyes locality, the variable green forage yield showed significant differences among treatments, T1 being the most outstanding one (21,1 t ha-1). Conclusions: During the rainy and dry seasons, T3 reached the best values in green forage and dry matter yield for the Pasto locality; while for Sapuyes, T1 showed the best values. [ABSTRACT FROM AUTHOR]

The objective of the study was to evaluate three ryegrass (Lolium perenne L.) cultivars with dairy cows, in the high tropic of Nariño-Colombia, in two localities: Pasto (PAS) and Cumbal (CUM). In each locality nine cows were used, in a Latin square design (3 x 3) with three treatments (T), corresponding to each cultivar to be evaluated: T1: ryegrass Columbia, T2: ryegrass Samson, T3: ryegrass Ohau. The dry matter intake (DMI) and milk production (MP) were estimated, and samples were collected to analyze: fat, protein, total solids and milk ureic nitrogen (MUN). There was no statistical difference in the DMI among the ryegrasses in the localities. In PAS significant differences were found among cultivars in the variable milk production (p < 0,05); with Samson and Ohau higher production was obtained (17,5 and 17,1 kg/cow/day) with regards to Columbia (15,5 kg/cow/day). In the content of fat and non-fatty solids in the milk, there were no differences among the treatments in any of the two localities. However, significant difference (p < 0,05) was found in the milk protein in PAS (3,48; 3,61 and 3,47 % for Columbia, Samson and Ohau, respectively). For the variable MUN (mg/dL), significant difference (p < 0,05) was observed in the PAS locality. It is concluded that L. perenne showed similar nutritional characteristics in the two localities where they were established. The response in milk production and compositional quality was considered good, taking into consideration that the animals did not receive supplementation and the trial was conducted in the dry season, in which the pasture yields decrease. [ABSTRACT FROM AUTHOR]

Forages are the prevailing feeding alternative within the different livestock production systems in the tropic; nevertheless, they often show limitations in quantity and quality. The objective of this study was to evaluate the productivity and quality of 18 forage species for their use in the high tropic of Nariño, Colombia. The trials were established in two localities (Pasto and Sapuyes). The design was completely randomized blocks, with 18 treatments and three repetitions: ten ryegrass cultivars, three naturalized pastures (kikuyu, Yorkshire fog and cock's foot), three legumes and two forage creeping non-legume plants (broadleaf plantain and common chicory). During the seasons of high and low rainfall, the following variables were evaluated: dry matter (DM), crude protein (CP), neutral detergent fiber (NDF), acid detergent fiber (ADF) and net lactation energy (NLE). During the two periods of high and low rainfall, the ryegrasses Aubade and Italiano; the perennial cultivars Yorkshire fog, Columbia and Boxer; the legume vetch and the non-legume creeping plants common chicory and broadleaf plantain showed the best CM, CP, NDF, ADF and NLE values in the two localities. The adaptation of the different ryegrass cultivars is a characteristic that affected the quality of the produced biomass. [ABSTRACT FROM AUTHOR]

A trial was conducted in order to evaluate the effect of Leucaena leucocephala cv. Peru on the rumen microbial population of Zebu crossbred bulls, in the two stages of the fattening cycle. The system, integrated by five strips of grasses associated with L. leucocephala and five without association, consecutively alternated in 25 ha, allowed the fattening of 80 animals, from which eight were used for the microbiological studies. The samplings of rumen liquid were made bimonthly (February-March, April-May, June-July) and four-monthly (August-November). The cellulolytic bacteria reached values between 15,94 and 46,13 106 CFU.mL-1 when the bulls grazed L. leucocephala associated with grasses. The highest population of rumen cellulolytic fungi was found in the rumen of animals in the system with L. leucocephala, in the August-November samplings. The concentration of rumen ammonia had values of 8,76 and 24,09 mmol.L-1 in the system with grasses and the one of L. leucocephala associated with grasses, respectively (p < 0,001). The pH in rumen was significantly higher, the population of total viable bacteria was 2,9 times higher and the protozoans decreased when L. leucocephala participated in the ration. It is concluded that the system with L. leucocephala associated with grasses is advantageous, because it propitiates increases in the populations of total viable bacteria and fiber-degrading microorganisms; this, along with the depressing effect of protozoans, guarantees a favorable ecological environment for rumen cellulolysis, which would contribute in a sustained way to the productive increase of the animal husbandry system. [ABSTRACT FROM AUTHOR]