The inclusion of forage mixtures in the diet of growing dairy heifers: Impacts on digestion, energy utilisation, and methane emissions

• Published in: Agriculture, ecosystems & environment ecosystems & environment, 2014-12, Vol.197, p.88-95
• Main Authors: Hammond, K.J., Humphries, D.J., Westbury, D.B., Thompson, A., Crompton, L.A., Kirton, P., Green, C., Reynolds, C.K.
• Format: Article
• Language: English
• Subjects: Achillea millefolium; Agronomy. Soil science and plant productions; Animal productions; Biological and medical sciences; Cattle; Centaurea nigra; Clover; Digestion; Energy; Flowers; Forage mixtures; Forages; Fundamental and applied biological sciences. Psychology; General agroecology; General agroecology. Agricultural and farming systems. Agricultural development. Rural area planning. Landscaping; General agronomy. Plant production; Generalities. Agricultural and farming systems. Agricultural development; Grazing; Greenhouse gas emission; Growth; Inclusions; Intakes; Leucanthemum vulgare; Lolium perenne; Lotus corniculatus; Methane; Nitrogen; Plantago lanceolata; Rumex acetosa; Ruminantia; Terrestrial animal productions; Trifolium pratense; Vertebrates
• ISSN: 0167-8809; 1873-2305
• DOI: 10.1016/j.agee.2014.07.016

•Heifers were fed 4 forage mixture sand their methane emissions and digestion measured.•Methane emission and forage digestibility were reduced by a wild flower mixture.•Forage CP content, intake, and ME supply were also reduced by the wild flower mixture.•Forage mixtures have environmental benefits for sustainable animal production systems. Intensive farming focusing on monoculture grass species to maximise forage production has led to a reduction in the extent and diversity of species-rich grasslands. However, plant communities with higher species number (richness) are a potential strategy for more sustainable production and mitigation of greenhouse gas (GHG) emissions. Research has indicated the need to understand opportunities that forage mixtures can offer sustainable ruminant production systems. The objective of the two experiments reported here were to evaluate multiple species forage mixtures in comparison to ryegrass-dominant pasture, when conserved or grazed, on digestion, energy utilisation, N excretion, and methane emissions by growing 10–15 month old heifers. Experiment 1 was a 4×4 Latin square design with five week periods. Four forage treatments of: (1) ryegrass (control); permanent pasture with perennial ryegrass (Lolium perenne); (2) clover; a ryegrass:red clover (Trifolium pratense) mixture; (3) trefoil; a ryegrass:birdsfoot trefoil (Lotus corniculatus) mixture; and (4) flowers; a ryegrass:wild flower mixture of predominately sorrel (Rumex acetosa), ox-eye daisy (Leucanthemum vulgare), yarrow (Achillea millefolium), knapweed (Centaurea nigra) and ribwort plantain (Plantago lanceolata), were fed as haylages to four dairy heifers. Measurements included digestibility, N excretion, and energy utilisation (including methane emissions measured in respiration chambers). Experiment 2 used 12 different dairy heifers grazing three of the same forage treatments used to make haylage in experiment 1 (ryegrass, clover and flowers) and methane emissions were estimated using the sulphur hexafluoride (SF6) tracer technique. Distribution of ryegrass to other species (dry matter (DM) basis) was approximately 70:30 (clover), 80:20 (trefoil), and 40:60 (flowers) for experiment 1. During the first and second grazing rotations (respectively) in experiment 2, perennial ryegrass accounted for 95 and 98% of DM in ryegrass, and 84 and 52% of DM in clover, with red clover accounting for almost all of the remainder. In the flowers mixture, perennial ryegrass was 52% o