Browsing by Author "Holmes CW"

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    Methane emission by alpaca and sheep fed on lucerne hay or grazed on pastures of perennial ryegrass/white clover or birdsfoot trefoil
    (CAMBRIDGE UNIV PRESS, 2003-03-01) Pinares-Patiño CS; Ulyatt MJ; Waghorn GC; Lassey KR; Barry TN; Holmes CW; Johnson DE
    Based on the knowledge that alpaca (Lama pacos) have a lower fractional outflow rate of feed particles (particulate FOR) from their forestomach than sheep (San Martin 1987), the current study measured methane (CH4) production and other digestion parameters in these species in three successive experiments (1, 2 and 3): Experiment 1, lucerne hay fed indoors; Experiment 2, grazed on perennial ryegrass/white clover pasture (PRG/WC); and Experiment 3, grazed on birdsfoot trefoil (Lotus corniculatus) pasture (Lotus). Six male alpaca and six castrated Romney sheep were simultaneously and successively fed on the forages either ad libitum or at generous herbage allowances (grazing). CH4 production (g/day) (using the sulphur hexafluoride tracer technique), voluntary feed intake (VFI), diet quality, and protozoa counts and volatile fatty acid concentrations in samples of forestomach contents were determined. In addition, feed digestibility, energy and nitrogen (N) balances and microbial N supply from the forestomach (using purine derivatives excretion) were measured in Experiment 1. Diets selected by alpaca were of lower quality than those selected by sheep, and the voluntary gross energy intakes (GEI, MJ) per kg of liveweight0.75 were consistently lower (P<0.001) for the alpaca than for the sheep (0.74 v. 1.36, 0.61 v. 1.32 and 0.77 v. 2.53 on lucerne hay, PRG/WC and Lotus, respectively). Alpaca and sheep did not differ (P>0.05) in their CH4 yields (% GEI) when fed on lucerne hay (5.1 v. 4.7), but alpaca had a higher CH4 yield when fed on PRG/WC (9.4 v. 7.5, P<0.05) and Lotus (6.4 v. 2.7, P<0.001). When grazing on Lotus, the sheep had very high protozoa counts in their forestomach contents, compared with those with the other forages and those in the alpaca. On lucerne hay and Lotus, but not on PRG/WC, the alpaca had higher (P<0.01) acetate/propionate ratio in their forestomach fluid than sheep. When fed on lucerne hay, alpaca and sheep did not differ (P>0.05) in diet N partition or microbial N yield, but alpaca had higher (P<0.05) neutral detergent fibre digestibility (0.478 v. 0.461) and lower (P<0.01) urinary energy losses (5.2 v. 5.8 % GEI) than sheep. it is suggested that differences between these species in forestomach particulate FOR might have been the underlying physiological mechanism responsible for the differences in CH4 yield, although the between-species differences in VFI and diet quality also had a major effect on it.
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    Persistence of differences between sheep in methane emission under generous grazing conditions
    (CAMBRIDGE UNIV PRESS, 2003-03-01) Pinares-Patiño CS; Ulyatt MJ; Lassey KR; Barry TN; Holmes CW
    Four low and four high methane (CH4) emitters were selected from a flock of 20 Romney sheep on the basis of CH4 production rates per unit of intake, measured at grazing using the sulphur hexafluoride (SF6) tracer technique. Methane emissions from these sheep were monitored at grazing for four periods (P): October, November, January and February 1999/2000. All measurements were carried out on perennial ryegrass/white clover pasture under generous herbage allowance, and the sheep were maintained on similar pastures during non-measurement periods. The tracer technique was used for all the CH4 measurements and feed DM intake was calculated from total faecal collection and estimated DM digestibility. Data for liveweight (LW), gross energy intake (GEI) and CH4 emission were analysed using split-plot analysis of variance. In addition, a between-period rank order correlation analysis was carried out for CH4 emission data. Low CH4 emitters were heavier (P<0.05) than the high emitters in all the periods, but they did not differ (P<0.05) in their gross energy intakes (GEI: MJ/kg LW0.75). Low and high CH4 emitters consistently maintained their initial rankings in CH4 yield (% GEI) throughout the subsequent periods and the correlation analysis of rank order for CH4 yield showed strong between-period correlation coefficients, although this was weaker in the last period. It is suggested that feeding conditions that maximize feed intake (e.g. generous allowance of good quality pasture under grazing) favour the expression and persistence of between-sheep differences in CH4 yield.
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    Rumen function and digestion parameters associated with differences between sheep in methane emissions when fed chaffed lucerne hay
    (CAMBRIDGE UNIV PRESS, 2003-03-01) Pinares-Patiño CS; Ulyatt MJ; Lassey KR; Barry TN; Holmes CW
    An indoor experiment involving 10 rumen-cannulated Romney sheep was conducted in May and June 1998 at AgResearch Grasslands, Palmerston North, New Zealand, under restricted feeding conditions, in order to test the hypothesis that animal factors, in particular rumen fractional outflow rate (FOR) and rumen volume, have an influence on the between-sheep variation in methane (CH4) emission. Sheep were fed 2-hourly on chaffed lucerne hay. Following an acclimatization period of 21 days, the experiment lasted 16 days. Energy and nitrogen (N) balances were measured on days 1-6. Cr-EDTA marker was continuously infused into the rumen from day 9 to 16, and rumen contents emptied and sampled on days 13 and 16. Particulate and fluid FOR were estimated using feed lignin and Cr-EDTA, respectively. Daily CH4 production was measured by the sulphur hexafluoride tracer technique on days 2, 5, 6, 12 and 15 of the experiment. CH4 production (g/day) was positively correlated with the pool size of organic matter (OM) in the rumen (OM pool, g) (r=0.84, P=0.002), OM intake (OMI, g/day) (r=0.67, P=0.04), and the rumen fill (g, wet digesta) (r=0.76, P=0.01). Multiple regression analysis showed that CH4 production was best predicted (R2=0.88) as a function of OM pool and the molar % of butyrate; however, OM pool alone accounted for a large proportion (R2=0.71) of the variation in CH4 production. CH4 yield (% gross energy intake, % GEI) was negatively correlated with the particulate FOR (%/h) (r= -0.75, P=0.01) and buffering capacity of rumen fluid (mmol HCl) (r= -0.72, P=0.02), but positively correlated with the digestibility of cellulose (r=0.66, P=0.04). Multiple regression analysis showed that CH4 yield was best predicted as a function of particulate FOR, OMI (g/kg liveweight0.75) and the molar % of butyrate (R2=0.88). Particulate FOR alone explained a large proportion (R2=0.57) of the variation in CH4 yield. Particulate FOR was negatively correlated with rumen fill (r= -0.69, P=0.03) and digestibility of cellulose (r= -0.65, P=0.04). These results suggest that sheep with lower rumen particulate FOR (i.e. longer rumen retention times) had larger rumen fills and higher fibre digestibilities and CH4 yields. If rumen particulate FOR is to be used as a tool for CH4 mitigation, the repeatability of its relationship to CH4 emission must be assessed, preferably under grazing conditions.