Use this URL to cite or link to this record in EThOS:
Title: The effects of feed composition and level on lactational performance in rats and dairy cows : a basic approach to feed description
Author: Friggens, N.
Awarding Body: University of Edinburgh
Current Institution: University of Edinburgh
Date of Award: 1990
Availability of Full Text:
Full text unavailable from EThOS.
Please contact the current institution’s library for further details.
An investigation into the effects of feed composition on lactational performance was carried out using rats and cows. A graphical representation of the feed as a triangle was used to aid the interpretation of results. The first rat experiment showed that, on high protein feeds, the lactational performance of rats is not depressed when offered feeds of very low carbohydrate content. This was substantiated by the other rat experiments. When carbohydrate in the feed was replaced by fat at low protein content (rat experiment 2) there was a large depression in lactational performance, effectively a cessation of mild production. The interaction between the three feed components protein, carbohydrate and fat was highly significant. The hypothesis that maternal heat production was limiting food intake was advanced. The third rat experiment used feeds whose composition was marginal in relation to lactational success. The feeds also allowed comparison between feeds of constant nutrient:energy ratio. The results of this experiment indicated that there is an extremely abrupt threshold in feed composition for adequate lactation. This effect could not be attributed to any one nutrient:energy ratio. This experiment also showed the importance of maternal body reserves in support of lactation. A model was developed to explore the hypothesis that maternal heat production was limiting performance, however this model failed. An experiment using sheep was conducted in order to permit prediction of the volatile fatty acid proportions arising from a range of feeds. This experiment was designed to allow application of the rat work to dairy cows. A dairy cow trial was conducted to compare different feed types and feeding levels. The results of this trial showed no effect of feed type on lactational performance. A linear relationship between food intake and level of milk production was found. This included an effect of feeding level on rate of decline in milk yield. All these findings are discussed in detail.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available