Oat silage for grazing dairy cows in small-scale dairy systems in the highlands of central Mexico

摘要

The objective was to evaluate the provision of oat silage (Avena sativa) to supplement grazing dairy cows on pastures of perennial ryegrass (Lolium perenne), festulolium (Lolium multiflorum x Festuca pratense) and white clover (Trifolium repens) during the dry season when pasture growth is limited. The experimental design was a 3x3 Latin square replicated three times, with nine milking Holstein cows (mean live weight 496.2 +/- 33.6 kg and daily milk yield 14.8 +/- 2.8 kg cow(-1)) under on-farm participatory rural research. Experimental periods were 14 d. Simulated grazing samples of pasture herbage were analysed for chemical composition, sward height recorded and net herbage accumulation determined from exclusion cages. Treatments were the inclusion of oat silage at T0 = 0 kg DM cow(-1) d(-1) of oat silage, T3 = 3 kg DM cow(-1) d(-1) of oat silage, and T6 = 6 kg DM cow(-1) d(-1) of oat silage, plus 5.0 kg fresh weight commercial concentrate and 9 h of continuous grazing. Animal variables were milk yield and composition, live weight and body condition score. Feeding costs were calculated. Mean milk yield was 18.9 +/- 0.27 kg cow(-1) d(-1) with no differences in animal variables (p > 0.05), but feeding costs per kilogram milk increased 25% for T3 and 50% for T6. Oat silage supplementation is only viable under difficult grazing conditions.