Multispecies swards enhance animal performance in a co-grazing cattle and sheep production system

Abstract

Grazing multispecies swards can have multiple benefits for the productivity and environmental sustainability of ruminant production systems. However, few studies have determined the effect of different sward−type systems on co-grazed cattle and sheep performance. The objective of this study was to determine the effect of different sward type systems: (1) a sown Lolium perenne (PRG) sward (receiving 170 kg of N/ha per year); (2) a pre-existing permanent pasture (PP) (receiving 135 kg N/ha per year); (3) a sown 6 species sward (6SP) with Lolium perenne, Phleum pratense, Trifolium pratense, Trifolium repens, Cichorium intybus and Plantago lanceolata (receiving 70 kg N/ha per year); and 4) a sown 12 species sward (12SP) with Dactylis glomerata, Lotus corniculatus, Onobrychis viciifolia, Achillea millefolium, Petroselinum crispum, Sanguisorba minor in addition to the 6SP listed above (receiving 70 kg N/ha per year); on the animal performance of co-grazed cattle and sheep. In 2020 and 2021, each sward−type system (9 ha) was rotationally co-grazed from April to November by dairy cross heifers (n = 20 per treatment per year, turned out at 395 ± 15 days of age, mean ± SD) and ewes (n = 22 ewes per treatment per year) plus lambs. Heifer live weight was recorded monthly, and heifers were drafted for slaughter when their estimated fat class on the EUROP grid scale reached 3-. Lamb live weight was recorded fortnightly, and lambs were drafted for slaughter at 42 kg (lambing to weaning), 44 kg (weaning to September) and 46 kg (after 1 September) to obtain a target carcass weight of 21 kg. Average daily gain (ADG) from turnout to slaughter was higher for heifers grazing the 6SP sward (1.09 kg/day) compared to all other sward types (12SP (0.99 kg/day), PRG (0.92 kg/day), and PP swards (0.92 kg/day); P < 0.001)). Lamb ADG from birth to slaughter in the 6SP (393 g/day) and 12SP (363 g/day) were greater than the PP (305 g/day; P < 0.001) or PRG swards (292 g/day; P < 0.001). Carcass dressing percentage was higher for lambs grazing the 6SP (48.5%) and 12SP (48.6%) compared to lambs grazing the PRG (44.7%; P < 0.001) and PP swards (44.6%; P < 0.001). Lambs grazing the 6SP and 12SP had a reduced number of grazing days from turnout to slaughter (82 and 93 days respectively) compared to the lambs grazing the PPG and PP swards (133 and 127 days respectively; P < 0.01). Overall, co-grazing multispecies swards improved heifer and lamb production performance at lower nitrogen fertilisation rates, potentially mitigating the environmental impact of beef and sheep production systems.