Oat and ryegrass silage for small-scale dairy systems in the highlands of central Mexico

This study investigated the effects of the inclusion of oat-ryegrass silage (ORGS) in combination with maize silage (MSLG) in four treatments: T1 = 100 % ORGS, T2 = 67 % ORGS/33 % MSLG, T3 = 67 % ORGS/33 % MSLG, and T4 = 100 % MSLG to milking cows on continuous grazing with 4.7 kg DM of commercial dairy concentrate 18 % CP. Daily milk yield and composition, live weight, body condition score, and chemical composition of feeds were recorded during the last 4 days of the experimental periods. Feeding costs were calculated by partial budgets. Eight Holstein lactating cows were used in a replicated 4 x 4 Latin square, with 14-day periods. There were no statistical differences (P > 0.05) for milk yield (mean 15.5 +/- 5.0 kg/day/cow) or composition (mean milk fat 34.6 +/- 4.4 g/kg, protein 32.4 +/- 3.1 g/kg, lactose 46.9 +/- 1.6 g/kg), milk urea nitrogen (11.3 +/- 2.1 mg/dl), live weight (434 +/- 38 kg), or body condition score (2.4 +/- 0.15). The silage cost of ORGS was 2.5 times higher than MSLG, so the feeding cost in T1 was 26 % higher per kilogram of milk than for T4, with T2 and T3 as intermediates. ORGS can be a substitute to maize silage in the proportions studied, although feeding costs were higher.