The potential of an all-grass diet for the late-winter calving dairy cow |
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| Authors: | R C RAE C THOMAS A REEVE A J GOLIGHTLY R G HODSON R D BAKER |
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| Institution: | Imperial Chemical Industries plc, Jealott's Hill Research Station, Bracknell;Animal and Grassland Research Institute, Hurley, UK |
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| Abstract: | In a trial lasting 3 years at Jealott's Hill and 2 years at Ravenscroft Hall, a total of 73 January- March-calving Friesian x Holstein cows and heifers were given a diet consisting almost exclusively of ensiled and grazed ryegrass for an entire lactation to establish the level of milk production which grass alone can support. From calving to turnout in April/May (average duration 87 days), the animals were given high digestibility (DOMD = 678g kg-1 DM) ryegrass silage ad libitum. After turnout, they grazed ryegrass swards until housing in autumn. Thereafter, the cattle were given ryegrass silage of lower digestibility (DOMD = 600–620 g kg-1 DM) for the remainder of the lactation and during the dry period.
Mean silage dry matter intakes from calving to turnout were 13–2 kg day-1 at Jealott's Hill and 11·5 kg day-1 at Ravenscroft Hall. Average milk yields were 21-1 kg day-1 for cows and 16-1 kg day-1 for heifers with 39-2g fat kg-1, 29-6g protein kg-1 and 47–9 g lactose kg-1. Over the complete lactation, average milk yields were 4680 kg and 4006 kg for the cows and heifers, respectively, with 39-4 g fat kg-1, 31·4 g protein kg-1 and 46·9 g lactose kg-1. Animal health and fertility were satisfactory. The results demonstrated the value of high quality grazed and ensiled ryegrass and provided a measure of milk production from grass only. |
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