Effect of perennial ryegrass (Lolium perenne L.) cultivars on the milk yield of grazing dairy cows

• Published in: Animal (Cambridge, England) Vol. 7; no. 3; pp. 410 - 421
• Main Authors: Wims, C. M., McEvoy, M., Delaby, L., Boland, T. M., O'Donovan, M.
• Format: Journal Article
• Language: English
• Published: Cambridge, UK Cambridge University Press 01.03.2013; Elsevier Limited; Published by Elsevier (since 2021) / Cambridge University Press (until 2020); Elsevier
• Subjects: Animals; Biomass; Breeding - methods; Breeding and genetics; Cattle - physiology; cultivar; cultivars; dairy cow; dairy cows; digestibility; Female; grasses; grazing; Holstein; Ireland; Life Sciences; Lolium - anatomy & histology; Lolium - growth & development; Lolium perenne; milk; Milk - metabolism; milk composition; milk yield; Models, Statistical; organic matter; perennial ryegrass; Species Specificity; sward; sward structure; vegetative growth; Ireland; sward structure; dairy cow; perennial ryegrass; cultivar; grazing; CULTIVAR; SWARD STRUCTURE; GRAZING; PERENNIAL RYEGRASS; DAIRY COW
• ISSN: 1751-7311; 1751-732X; 1751-732X
• DOI: 10.1017/S1751731112001814

The objective of this experiment was to investigate the effect of four perennial ryegrass cultivars: Bealey, Astonenergy, Spelga and AberMagic on the milk yield and milk composition of grazing dairy cows. Two 4 × 4 latin square experiments were completed, one during the reproductive and the other during the vegetative growth phase of the cultivars. Thirty-two Holstein–Friesian dairy cows were divided into four groups, with each group assigned 17 days on each cultivar during both experiments. Within each observation period, milk yield and milk composition, sward morphology and pasture chemical composition were measured. During the reproductive growth phase, organic matter digestibility (OMD) was greater for Bealey and Astonenergy (P < 0.001; +1.6%). AberMagic contained a higher stem proportion (P < 0.01; +0.06) and a longer sheath height (P < 0.001; +1.9 cm). Consequently, cows grazing AberMagic recorded a lower milk yield (P < 0.001; −1.5 kg/day) and a lower milk solids yield (P < 0.001; −0.13 kg/day). During the vegetative growth phase, OMD was greater (P < 0.001; +1.1%) for Bealey, whereas the differences between the cultivars in terms of sward structure were smaller and did not appear to influence animal performance. As a result, cows grazing Bealey recorded a higher milk yield (P < 0.001; +0.9 kg/day) and a higher milk solids yield (P < 0.01; +0.08 kg/day). It was concluded that grass cultivar did influence milk yield due to variations in sward structure and chemical composition.