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Title: Changes in body composition of ruminants during early lactation
Author: Cowan, R. T.
Awarding Body: University of Aberdeen
Current Institution: University of Aberdeen
Date of Award: 1980
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Changes in the chemical composition of the body during early lactation were measured by comparative slaughter and deuterium dilution in three experiments using Border Leicester x Scottish Blackface and Pinntsh Landraoe x Dorset Horn ewes. The effects of different levels of body fatness at lambing and different metabolizable energy and crude protein intakes during lactation were studied. Chemically determined fat was lost from the carcass, hide, udder, liver, gut walls and the internal fat depots. The ranking of the tissues and organs for the relative rate of fat lose was consistent in the various treatments, and the absolute rate of fat lose depended on body fatness at lambing and metabolizable energy intake during lactation. Lose of body protein was less than 12 per cent of total body protein, but there were relatively greater losses from the carcass and the udder and gains in the gut walls. Live-weight change grossly underestimated loss of body energy, owing to increases in both weight of gut contents and hydration of the empty body. The efficiency with which body energy was used for milk synthesis appeared low at high rates of lose of body fat, and it was suggested that a low dietary intake of protein may have limited the use of this energy for milk synthesis. It was not possible to use one overall regression utilizing deuterium oxide space to estimate the weights of fat in living ewes during early lactation as the relationship between deuterium oxide space and total body water was different between early and midlactation. This difference was associated with different rates of water turnover. When similar treatments to those used with ewes were applied to dairy cows the general relationships among food intake, milk production and nitrogen balance suggested the effects of changes in body composition on production were similar in both species.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available