Produccion, composicion quimica y aptitud fermentativa de dos variedades [California 40, Criolla] de alfalfa (Medicago sativa L.) en la provincia de Valdivia.

In order to determine the production, chemical composition and ensilability of two varieties of lucerne, California 40 and Criolla, two experiments were conducted simultaneously. In the ensilability exp. the treatments were determined by three cutting stages; flower bud, 30% of flowering and full flowering. In the fermentation exp. ability, it was determined that only the metabolizable energy was different (P<= 0,05) between varieties. California 40 had 2.47 Mcal/kg DM vs. 2.38 Mcal/kg DM of Criolla. The variation between the different growth stages for total protein, crude fibre and total ashes was not significant (P> 0,05). The percent DM increased from 23.88% to 34.61%. The metabolizable energy decreased from 2.53 to 2.33 Mcal/kg DM. Both differences were significant (P<= 0,01). The analysis to determine the fermentation ability showed differences between varieties. The buffer capacity was higher in Criolla: 455.56 meq/kg DM vs. 410.91 meq/kg DM for California 40 (P <= 0,05). The organic acid content was higher in California 40: 747.4 meq/kg DM vs. 681.1 meq/kg DM for Criolla. Soluble carbohydrates varied between varieties, California 40 with 30.27 g/kg DM and 35.85 g/kg DM, for Criolla (P> 0,05). With the advance in maturity all parameters determining the fermentation ability including pH decreased significantly (P<= 0,01). The buffer capacity was reduced from 540.76 meq/kg DM to 366.82 meq/kg DM, the organic acid content from 969.32 meq/kg DM to 506.26 meq/kg DM, solubles carbohydrates from 44.82 g/kg DM to 28.98 g/kg DM and pH from 5.27. In the second experiment to compare the production a chemical composition, the treatments were defined by two varieties. The stage of cut was defined by 20% of flowering, or when the coronet sprouts was 5 cm. For each variety and each cut three replications were used. The cut dates were December 7th of 1990, January 24th, March 20th and June 7th of 1991. In the first, third and fourth cut there were no significant differences for neither of the parameters (P> 0,05) (Fresh matter, dry matter, % of DM, total protein (%), metabolizable energy (Mcal/kg DM) and botanical composition (% of pure lucerne)). In the second cut the differences obtained were significant. The level of significance were (P<= 0,01) for fresh matter yield (kg FM/ha), dry matter yield (kg DM/ha) and dry matter percent. For the total protein (%) a significant difference was found (P<= 0,05). No significant differences in total production were found (P> 0,05). The production expressed in (kg FM/ha) of California 40 was 36683.83 vs. 37786.76 of Criolla. The dry matter (kg DM/ha) obtained with California 40 was 9084.17 vs. 7716.33 of Criolla. The average percent lucerne in the experimental plots was 66.17% for California 40 vs. 66.75 of Criolla.