Browsing by Author "Swainson, Natasha Madeleine"

Now showing 1 - 2 of 2
  • Thumbnail Image
    Item
    Methane emissions and mitigation technologies in cattle, sheep and red deer : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Animal Science at Massey University, Palmerston North, New Zealand
    (Massey University, 2011) Swainson, Natasha Madeleine
    Enteric fermentation of ingested feed by ruminant livestock is an important source of methane (CH4), a potent greenhouse gas (GHG). Ruminant CH4 emissions contribute approximately 31% of New Zealand‟s total GHG inventory; therefore reducing CH4 emissions from ruminant livestock is a national priority. The aims of this research were to investigate the effectiveness of potential mitigation technologies on the CH4 emissions in sheep. This included the supplementation of monensin and coconut oil, individually or in combination, and the feeding of chicory as an alternative forage to perennial ryegrass-based pasture (pasture). The influence of ruminant age (grazing red deer) and ruminant species (housed cattle, sheep and red deer) on CH4 yield were also explored. This research showed that the supplementation of monensin to sheep may provide reductions in CH4 yield (g CH4/kg dry matter intake, DMI) of up to 30%, but this was not consistent between experiments. Sheep fed chicory yielded less CH4 (17%) compared with sheep fed pasture, which was suggested to be due to faster degradation rates of chicory, leading to the increased outflow rate of digesta from the rumen; this theory needs to be tested. Neither, the supplementation of coconut oil or the combination of mitigation technologies resulted in a significant reduction in CH4 yield. Nevertheless, as the power to detect a significant difference between treatments was reduced, due to the high variability of estimated CH4 production, it is recommended that the effects of combined mitigation technologies be retested. Methane yield was influenced by deer age, but only at 4.5 months of age as CH4 yields of deer aged 6.5 to 11.5 months did not differ and may be an artefact of the method used to estimate DMI. Mean differences of CH4 yield (up to 32%) between ruminant species was found when animals were offered the same diet and constant feeding levels; cattle > sheep > deer. This study indicates that the use of a single ruminant species to model potential CH4 mitigation technologies may not represent all target populations due to differences of age or species found in this study. Research is required to confirm if differences between ruminant species persist when animals are fed fresh forages and to determine if responses to potential mitigation technologies are similar with age or between ruminant species.
  • Thumbnail Image
    Item
    Methane emissions from farmed red deer : a thesis in partial fulfilment of the requirements for the degree of Master of Science in Animal Science at Massey University, Palmerston North
    (Massey University, 2004) Swainson, Natasha Madeleine
    Methane (CH4) is one of the end products of fermentation of ingested feed by the microbial population residing in the foregut of ruminants. It represents a potential loss of 2-12% of gross energy consumed, and is a potent greenhouse gas. The objective of this study was to firstly measure methane emissions for the first time using the sulfur hexafluoride tracer technique in red deer (Cervus elahus) grazing ryegrass-based pasture (Lolium perenne) and secondly, to compare methane emissions of deer grazing chicory (Cichorium intybus) and plantain (Plantago lanceolata) with those grazing ryegrass-based pasture. Methane production per day and per kg of dry matter intake (DMI) was measured using the sulfur hexafluoride tracer technique coupled the with η-alkane technique for feed intake estimation in 25 red deer grazing ryegrass-based pasture, chicory or plantain in March and May of 2003. Methane production per unit DMI obtained in this study (37.8 g / kg DMI) was approximately 75-80% greater than values used in the New Zealand National Greenhouse Gas Inventory for dairy cows and sheep, and estimated for deer grazing ryegrass-based pastures. Deer grazing chicory and plantain in March exhibited lower methane emissions per kg DMI compared with ryegrass-based pasture. However, in May methane emissions per kg of DMI from plantain was similar to pasture, which were both higher compared with chicory. The variability and accuracy of results obtained for estimated DMI using the alkane technique was questioned, and a lack of published information regarding methane production by red deer provided few possible explanations for the apparently high methane emissions. This prompted the initiation of an indoor study where DMI could be accurately measured concurrently with methane production using 12 animals from the grazing study. Mean methane production per kg DMI of 12 mature hinds housed individually indoors in metabolism cages and fed fresh ryegrass-based pasture in August 2003 was 22.5 g CH4/kg DMI. This figure was similar to published results obtained from sheep and cattle on similar diets and was 42% lower than the grazing study in autumn. This latter result emphasises the importance of obtaining accurate individual DMI measurements with which to express methane emissions per unit feed intake. Estimated dry matter intakes using the double n-alkane technique have not previously been validated against actual intakes for red deer, or for deer fed fresh forages. Therefore, the third experiment attempted to validate the use of this technique with rumen-fistulated, castrated red deer stags housed indoors and fed either fresh ryegrass-based pasture or plantain, while concurrently measuring methane production. Indirect estimation of DMI using the double n-alkane technique underestimated actual DMI of pasture by 23.5% and overestimated actual DMI of plantain by 13.9%. These results indicate that the estimation of DMI by the double n-alkane technique was possibly not valid for comparisons between treatments, and across experiments or animal species. The impact on methane emissions of the inaccurate estimation of DMI by the double n-technique resulted in methane production from deer fed pasture being overestimated by 11.0 g CH4/kg DMI and an underestimation of methane production of 4.8 g CH4/kg DMI for deer fed plantain. Findings of this thesis suggest that the measurement of methane from grazing and/or forage-fed animals should be conducted under conditions where DMI can be measured accurately, otherwise comparisons of methane production across treatments, experiments or species may be invalid. The latter two studies indicate that methane production of forage-fed red deer is similar to published values for sheep and cattle. However, this should be confirmed by direct comparisons where all species are fed the same diet, methane measurements are conducted over the same time period using identical methods, and feed intake can be accurately determined.