Herbage production, botanical and plant-part composition of mixed black oat (Avena strigosa Scherb.) annual ryegrass (Lolium multiflorum Lam.) pastures under different management strategies.

Abstract

Mixing annual ryegrass and black oat can improve forage production in subtropical and temperate areas with integrated croplivestock systems. Thus, we evaluated the forage production dynamics of mixed annual ryegrass-black oat pastures under different management strategies based on canopy height and supplement level. Pastures were continuously stocked with Boer goats at two grazing heights (12 or 21 cm); animals received or did not receive energy supplements (0 and 15 g kg-1 of body weight). These treatments were applied using a factorial scheme (2 × 2) and randomized block design with three replications. We evaluated the herbage accumulation rate (kg of DM h-1 day-1) using the exclusion cage technique, herbage mass (HM, kg of DM ha-1) using the double sampling technique, and botanical and plant-part composition (%) of destructive samplings. Supplementation had no effect on the parameters measured (P ≤ 0.05). Annual ryegrass become the predominant species during the experimental period and mainly at the lowest canopy height. Total herbage production during the 131 days of pasture utilization was 10,280 kg of DM ha-1. The herbage accumulation rate was similar between the two canopy heights; however, it varied throughout experimental period. Leaf lamina mass was lower in treatments 12 cm up to 102 after sowing; after that, they were equivalent. At the end of the study, herbage mass was 2720 kg DM ha-1 with the 21-cm treatment and 2170 kg DM ha-1 with the 12-cm treatment. It is recommended to maintain mixed annual ryegrass-black oat pastures at 12 cm in height. Reasons are discussed throughout the text.