Conserved forage as a buffer feed for dairy cows

Phillips, C. J. C (1983) Conserved forage as a buffer feed for dairy cows. PhD thesis, University of Glasgow.

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Abstract

The literature concerning the reasons for and the effects of a restriction of the forage intake of dairy cows (grazed herbage in summer, grass silage in winter), and the effects of providing additional conserved forage as a buffer feed, is reviewed. 2) In a 24 week experiment with grazing dairy cows the effects of stocking rate and the provision of hay as a buffer feed were examined. Herbage intake was restricted by stocking cows at a higher rate and during inclement weather. Offering hay increased total DM intake and milk yield but had no effect on milk composition. Details of grazing behaviour (in particular grazing and ruminating times) were obtained at monthly intervals. 3) A second experiment examined the response to a buffer feed of silage during the early part of the grazing season. Silage was offered either after morning milking, or indoors overnight at a restricted level or ad libitum. Offering silage had no effect on total DM intake, slightly reduced milk yield but increased milk fat content. The behaviour of the cows was recorded both indoors and at pasture and showed that grazing times were depressed by offering silage. 4) A similar experiment examined the response to a buffer feed of silage in the late grazing season. Offering silage increased total DM intakes which increased animal production, particularly when silage was offered overnight ad libitum. Similar grazing behaviour studies to the previous experiment were carried out. 5) In a winter feeding regime an initial changeover experiment with three week periods examined the effects of restricting the silage ration and of offering hay as a buffer feed. Restricting silage intake primarily resulted in loss of live weight and offering hay increased total DM intake and milk yield. 6) A second changeover experiment, also with three week periods, examined the effects of a greater restriction of silage intake, and of offering straw or ammonia-treated straw as a buffer feed. Restricting silage intake resulted in loss of live weight and reduced milk production. The intakes of straw or ammonia-treated straw were too low to restore forage DM intakes and consequently were of little value in increasing animal production. 7) A final experiment in a winter-feeding regime examined the effects of a longer-term restriction of silage intake, and the provision of a nutritionally-formulated strawmix as a buffer feed. Restricting the silage ration resulted in loss of live weight compared to cows offered ad libitum silage. Provision of strawmix as a buffer feed to restricted silage restored forage DM intakes to ad libitum levels but did not prevent loss of live weight, although it was of some benefit in improving milk composition. 8) The effect of offering a buffer feed in reducing the daily variation in forage DM intakes and milk yields is also studied in these experiments. In addition, the differences between cows and heifers in their response to forage restrictions are examined, in particular the effect on ingestive behaviour. The effects of restricting forage intake and of offering buffer feeds on farm stocking rate are considered - farm stocking rate can be increased by restricting forage intake, and loss of milk production averted by the provision of a purchased buffer feed.

Item Type: Thesis (PhD)
Qualification Level: Doctoral
Additional Information: Adviser: J D Leaver
Keywords: Animal sciences
Date of Award: 1983
Depositing User: Enlighten Team
Unique ID: glathesis:1983-73357
Copyright: Copyright of this thesis is held by the author.
Date Deposited: 14 Jun 2019 08:56
Last Modified: 14 Jun 2019 08:56
URI: http://theses.gla.ac.uk/id/eprint/73357

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