Sheep from low-methane-yield selection lines created on alfalfa pellets also have lower methane yield under pastoral farming conditions

Abstract

Selection lines of sheep with low and high CH yield (g/kg DMI; CH/DMI) are being developed on the basis of feeding pelleted alfalfa hay at 2.0 times maintenance ME requirements in respiration chambers, but their divergence under predominant grazing conditions, as in New Zealand, is not known. The objectives of this study were to determine CH emissions and rumen fermentation characteristics in sheep from low and high CH/DMI selection lines while grazing pasture. Two grazing experiments were conducted with 42 selection line ewes in March 2013 (Exp. 1) and 98 selection line progeny ewe hoggets in October/November 2014 (Exp. 2), with CH emissions estimated by the SF tracer technique and DMI estimated by titanium oxide in combination with natural long-chain -alkanes. Total daily CH production (g/d) was similar between high and low CH/DMI selection line sheep in Exp. 1 and lower for low CH/DMI progeny compared with high CH/DMI progeny in Exp. 2 ( < 0.05). The CH/DMI tended to be 20% lower for low CH/DMI line sheep compared with high CH/DMI selection line sheep in Exp. 1 ( < 0.10) and was 15% lower for the low CH/DMI line in Exp. 2 ( < 0.01). Total VFA concentration and concentrations (m) of acetate, butyrate, and isobutyrate plus isovalerate were lower ( < 0.05) for low CH/DMI line sheep compared with high CH/DMI selection line sheep in both experiments. The current study indicates that differences in CH/DMI and VFA concentrations in selection line sheep, previously established on alfalfa pellets, are also present to a similar magnitude when grazing pasture.

Genetic parameters of plasma and ruminal volatile fatty acids in sheep fed alfalfa pellets and genetic correlations with enteric methane emissions1

“…The VFA proportions were also in a range similar to those reported by Sun et al (2012) for sheep fed a range of fresh forages. Rumen VFA concentrations were also found to be lower, as in the present study with alfalfa pellets, in low compared with high CH 4 yield sheep fed cut pasture (Jonker et al, 2017a).…”

Persistence of differences between dairy cows categorized as low or high methane emitters, as estimated from milk mid-infrared spectra and measured by GreenFeed

“…Results from cows on different farms might differ, but at least the persistence of the differentiation across the 2 contrasting feeding regimens in the present study indicates an underlying category effect. Consistent with this, Jonker et al (2017) reported that differences in MeY in selection lines of sheep, selected beforehand on an alfalfa pellet-based diet, were also present to a similar magnitude when grazing pasture. In another study, repeated measurements of MeP on contrasting diets (pellets vs. grass) revealed that sheep maintained their initial categorization, although the magnitude of difference between the 2 category groups varied by diet (Pinares-Patiño et al, 2011).…”

“…Others were able to display consistent between-animal differences in CH 4 yield (MeY, g/kg of DMI) over an experimental period of 3 mo and between 2 different diets with growing sheep (Pinares-Patiño et al, 2011). Jonker et al (2017) showed that the progeny of sheep selected for low and high MeY, as determined by RC, also had different MeP. Other studies give clear indications that MeP, MeI, and MeY are heritable traits (h 2 = 0.21 for MeP and 0.25 to 0.22 for MeI; Lassen and Løvendahl, 2016;Kandel et al, 2017).…”

Sustainable Biorefinery and Production of Alfalfa (Medicago sativa L.)

“…(8) Alfalfa pellets are a highly proteinaceous feed that contains high protein concentration (up to 20%), carotene, and energy for feeding livestock (Jonker et al, 2017;Patra & Paul, 2019).…”