Abstract
Meat is still the most consumed protein source, especially in developed countries and ruminant meat has an important market share. However, it is marine food sources and plant-based food that are excellent suppliers for poly-unsaturated fatty acid (PUFA), particularly omega-3, which are recommended for human consumption due to their health attributes, nonetheless consumed to a lesser extent than meat. Hence, omega-3 enriched meat and animal products are coming to the market to compensate for this intake deficiency. The challenges of increasing omega-3 in red meat through lipids supplementation to ruminants lies in the lipolysis and biohydrogenation seen in the rumen, as the double-bonded molecules (i.e., in PUFA) create a toxic environment for the bacteria. This results in the formation of monounsaturated fatty acids (MUFA) and then saturated fatty acids (SFA). Dietary supplementation of some strains of microalgae have given good results in terms of enhancing omega-3 content in ruminant meat, however no comparison was made between the supplementation of docosahexaenoic acid-rich (DHA, C22:6), a long chain omega-3 PUFA, in different forms, but from the same genus.Consequently, this study investigated the effect of both DHA-rich microalgae cells and separately their extracted oil on the rumen microbiome via in vitro incubation. The project also provides more in-depth knowledge on the impact of Schizochytrium sp. supplementation on fatty acid profiles of different raw and cooked lamb meat cutlets, whilst also assessing the underlying changes in the gastrointestinal tract (GIT) microbiome. Finally, sensory parameters of enriched meat products are often assessed by a trained panel, and reported with “fishy”, “oily”, “seaweed” off-flavours, especially in the case of fish oil supplementations. Therefore, this study investigated the palatability and acceptability of lamb burgers, enriched with different levels of Schizochytrium sp. using a consumer panel. The in vitro incubations to study the effects of Schizochytrium sp. on rumen fermentation were conducted at equal DHA concentration, using Schizochytrium sp. cell form and extracted oil form, monitoring using ANKOM gas production system jars. The structure of Schizochytrium sp. cells were observed after in vitro incubation in a DaisyII incubator. Samples taken over time from the jars were analysed for volatile fatty acids (VFA), ammonia, protein and the rumen microbiome. Two in vivo studies were also conducted, one with 30 Easy-Care ram lambs allocated into 3 treatments (No supplementation (Control), 10.7 g biomass/head/day (Low) and 21.4 g biomass/head/day (High)) fed fresh grass and concentrates (50:50 energy based). The second one with 60 Texel crossed neutered lambs allocated into 4 treatments (No supplementation (Control), 10.7 g biomass/kg concentrates (Low), 21.4 g biomass/kg concentrates (Medium) and 32.1 g biomass/kg concentrates (High) fed grass silage and concentrates (50:50 energy based). From the first in vivo analysis, samples from different time points and different parts of the GIT (i.e., rumen, small intestine, large intestine) were kept to analyse VFAs, ammonia and the GIT microbiome. From both of the in vivo studies, the meat of the animals was collected for fatty acids analysis and from the second in vivo study, the meat was offered to a consumer panel for sensory assessment. The data obtained throughout this project showed no detrimental effect of the supplementation with whole cells or extracted Schizochytrium sp. oil on the rumen microbiome or its functioning.
The data also suggested that the supplementation of Schizochytrium sp. as whole cells would limit the access to the unsaturated lipids due to the cell wall. A beneficial impact of the dietary supplementation with microalgae on the health properties of lamb meat was observed in both in vivo studies. In the first study, beneficial consumption was particularly emphasised in the loin and leg muscles. This enhanced quality meat caused no detriment to the lambs’ growth or ruminal health. Finally, the project suggested the commercial potential of meat from lamb supplemented with Schizochytrium sp., as no difference in the palatability or appreciation was found in the enriched burgers as compared with the non-enriched, whilst improving human health at a medium inclusion concentration.To the best of our knowledge, this project provides novel data by comparing the supplementation of Schizochytrium sp. under two different forms in vitro, directly comparing the effect of the biomass supplementation in raw and cooked meat, from different cutlets and using a consumer panel for the assessment of the omega-3 enriched lamb meat.
Thesis embargoed until 31st July 2025.
Date of Award | Jul 2023 |
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Original language | English |
Awarding Institution |
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Sponsors | Devenish Nutrition Limited |
Supervisor | Nigel Scollan (Supervisor) & Sharon Huws (Supervisor) |
Keywords
- Ruminant
- sheep
- microbiome
- fatty acids
- microalgae
- docosahexaenoic acid
- palatability