Jebrell, Moutasim Bellah Khalid Jebrell2022-05-262022-05-262021http://hdl.handle.net/10179/17133This thesis is composed of a series of studies which assess the nutritional value of New Zealand flax (Phormium Tenex; Harakeke) for grazing ruminants. Flax samples of leaf sections from the top (FT) and bottom (FB) of the plant were evaluated using laboratory analyses and in vitro rumen fermentation and compared with predominant pastures forages in New Zealand, such as perennial ryegrass (NRG), chicory (NGHI), lucerne (NLUC), and white clover (NWC). The FT contained high concentrations of neutral detergent fibre (NDF) and acid detergent fibre (ADF), 67.6 and 53.2% of the dry matter (DM), respectively. Similarly, FB contained high levels of NDF and ADF 56.5 and 45.0% of the DM; respectively, compared with other forages (NRG, NCHI, NLUC, and NWC), which ranged between 24.9- 47.6% of the DM for NDF and 11.6-22.1% of the DM for ADF. Crude protein (CP) levels in FT and FB in contrast were lower (6.0 and 2.4% of the DM, respectively) compared with the other forages (NRG, NCHI, NLUC, and NWC), which had a CP range of 21-31.6% of the DM. An in vitro fermentation method measured gas production over 24 hours, and ammonia (NH₃) and volatile fatty acid (VFA) concentrations at 2, 4 and 8 h. For in vitro gas production two experiments were conducted (Experiments 5 and 6) and values were lower in Experiment 5 than Experiment 6, and lower than expected. However, in both experiments accumulated gas production for FT and FB were lower than the other forages at all time points. Cumulated gas production for FT, FB, NRG, NCHI, NLUC, and NWC was 38.50, 71.16, 84.12, 102.84, 76.66, and 85.48 ml gDM⁻¹, respectively. In experiment 6, accumulated gas production for FT and FB was also the lowest at 100.61, and 142.90 ml gDM⁻¹ , respectively. This compared with 180.76, 195.73, 166.83, and 181.09 ml gDM⁻¹ for the other forages (NRG, NCHI, NLUC, and NWC, respectively). In both experiments FB had 50-70% greater gas production than FT samples. Therefore, samples from the base of the Flax should be considered for further investigation in terms of gas production. Ammonia (NH₃) concentration and VFA yield were determined at 2, 4, and 8 h of incubation. The in vitro net NH₃ production (mmol NH₃ molN⁻¹) of FT (0.2), and FB (-4.4), were the lowest compared with NRG (3.1). For VFA yield, total VFAs(tVFA) produced (ml gDM⁻¹) from NRG was 120.03, which was higher than that of FT (40.35) and FB (36.11) after 8 h of incubation. For FT, FB, and NRG the percentage of acetate was, 70.2, 63.5, and 62.6%, respectively; propionate was 13.2, 13.7, and 23.2%, respectively; and butyrate was 13.7, 19.3, and 12.3% respectively In conclusion, New Zealand flax leaf sections had lower in vitro fermentation characteristics, and cumulative gas production than standard New Zealand forages. This study concluded that flax leaf sections were lower-quality forages when compared with New Zealand forages in terms of nutritive quality, in vitro fermentation, and gas production. However, the high NDF and ADF and low CP content of New Zealand flax samples suggests it could be fed as a supplement to forages for dry grazing ruminants without major problems.enThe AuthorThesis300303 Animal nutrition