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The effect of feeding microalgae on rumen fermentation, milk and cheese fatty acid profile and fertility in dairy cows

Till, B.E. (2018) The effect of feeding microalgae on rumen fermentation, milk and cheese fatty acid profile and fertility in dairy cows. Doctoral thesis, Harper Adams University.

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Abstract

The objectives of this thesis were to determine the effects of Algae (ALG), a supplement high in docosahexaenoic acid (DHA), on the biohydrogenation rate of DHA in vitro, and the effect feeding ALG to dairy cows had on milk FA profile and indicators of fertility. The first study was conducted in vitro to determine the effect of different inclusion levels of ALG or fish oil (FO) on the biohydrogenation of DHA. Results showed that DHA was extensively biohydrogenated at all time-points but was lower at the higher inclusion levels of ALG. The first cow study investigated the effect of rate of inclusion of ALG (0, 50, 100 or 150 g/ALG per cow/d) on milk and cheese FA profile, and cheese taste. The results demonstrated differences (P < 0.05) in milk fat yield, diet digestibility and milk and cheese FA profiles, but no difference (P > 0.05) in DM intake, milk yield, or cheese yield. A number of cheese taste attributes were affected. Milk and cheese DHA content were increased by 0.29 g/100 g. The second cow study determined the effect of long-term feeding of ALG on milk FA profile, and indicators of fertility. Cows were fed 100 g/ALG per day from 3 weeks post calving for 14 weeks. Results showed no differences (P > 0.05) in DM intake, milk yield or milk fat yield, but there were differences (P < 0.05) in the milk FA profiles and milk progesterone levels, with milk DHA content increasing in the ALG fed cows from week 2 of study onwards, and peaking at week 14 at 0.38 g/100 g. Plasma concentrations of the prostaglandin F2α metabolite were not significantly (P = 0.126) lower in ALG fed cows who had improved overall conception rates (55.6 % v.48 %). It was concluded from these experiments that supplementation of 100 g/ALG per cow/d is the most appropriate inclusion level to increase milk DHA content, avoiding rumen adaptation and negative effects on animal performance.

Item Type: Thesis (Doctoral)
Divisions: Animal Production, Welfare and Veterinary Sciences
Depositing User: Ms Kath Osborn
Date Deposited: 06 Feb 2019 16:42
Last Modified: 06 Feb 2019 16:42
URI: http://hau.collections.crest.ac.uk/id/eprint/17370

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