Chemical composition and in vitro gas production of forage cereals associated with common vetch (Vicia sativa)
Cereal grain forages and legume silages are an important part of dairy cattle rations in many parts of the world. The increasing importance of these crops as feedstuffs has highlighted the need to understand the factors, which influence their nutritive value. The use of in vitro gas production (GP) techniques to estimate digestibility of feeds was based on empirical relationships between digestibility and in vitro gas production. The objectives were to evaluate forage yield, chemical composition and in vitro gas production of some varieties of spring triticale (T-UAEMex and Siglo XXI), barley (Doña Josefa) and its association with common vetch (CV). The experimental unit consisted in seven rows, each 50 linear meters by 30 cm wide (with two lines of planting and spaced at 80 cm). The planting density was 80,000 plants/ha, harvested at 145 days (milky-dough stage) and ensiled in three repetitions, at 60 days the samples were opened from micro-silos (2 kg FM), and chemical composition was determined, GP profiles were determined using a semi-automated pressure transducer technique. Approximately 800 mg of each substrate was weighed into 125 ml serum bottles and incubated in a water bath at 39 ◦C with 10 ml strained rumen fluid and 90 ml of medium. The volume of gas produced was recorded at 3, 6, 9, 12, 24, 36, 48, 72 and 96 h of incubation. Each sample was incubated in triplicate in three series in different weeks. Data were analyzed by a completely randomized design. There were differences (P<0.001) in DM (dry matter) production, being greater T-Siglo XXI and associated with CV (6.50 and 5.4 ton DM/ha respectively), the greater CP content (P<0.001) was for CV (217 g/kg) and their associations (185 g /kg). No significant differences (P>0.05) were observed among varieties and their associations in NDF contents. Barley had a greater content (P<0.05) of NEl 1.5, and NEg0.9 (Mcal/kg DM). GP was greater for the association Barley - CV (P<0.05) (124±6 ml gas/g DM) compared to the rest (117±3 ml gas/g DM). Considering its nutritional quality and energy content forage cereals associations with CV are an option with higher forage yield and improved nutritional content for feeding livestock.
Keywords: Common vetch, Silage, In vitro Gas Production.