FOTO: HERBERT WIGGERMAN


SUSTAINABILITY ▶▶▶


Oats instead of barley: A good choice to reduce methane


compromising animal performance. BY MATTHEW WEDZERAI, CORRESPONDENT


B


Researchers from the Swedish University of Agricultural Sciences found that barley can be replaced with oats in the diet of dairy cows fed a grass silage-based diet, to mitigate CH4


emissions without


supplements comprised 30% of the diet DM. Barley was gradually substituted as follows: • 100% barley: 0% oats • 67% barley: 33% oats • 33% barley: 67% oats • 0% barley: 100% oats


Enteric methane emissions Increased inclusion of oats linearly reduced CH4


esides the contribution of methane to greenhouse


gas emissions, studies show that production of CH4 from cows represents an energy loss ranging from 2 to 12%, depending on the diet. As a result, in ad-


dition to the continuous search for feed additives, it is equal- ly important to compare the effects of the common basal in- gredients on methane production. In temperate climates, oats and barley are commonly used as concentrate supple- ments in the diet of dairy cows. Previous production studies have found that replacing barley with oats maintains milk yields at the same level and can even increase the milk yield of dairy cows.


The previous in vitro study The researchers working on the current study predicted the results of comparing barley and oats mainly based on the previous in vitro study. In that study, the CH4


of oats compared to barley was confirmed; there was 8.9% lower CH4


emissions from incubated oat-based diets compared to barley-based diets.


The Swedish study In this study, researchers evaluated the effects of gradually replacing barley with oats on enteric CH4


emissions by


4.4%, and methane intensity decreased (expressed as g/kg of ECM (energy-corrected milk)) by 4.8% when barley was com- pletely replaced by oats in the diet – indicating that CH4


sions were mitigated without compromising animal produc- tivity. In addition, the ratio of CH4


to CO2 decreased with


increasing inclusion of oats in the diet. The researchers remarked that “it is well known that there is a positive relationship between diet digestibility and CH4 sions. The decrease in CH4 emissions when replacing barley


emis-


with oats may be explained by the linear decrease in organic matter digestibility, because enteric CH4


arises from digested mitigating effect


matter. Another possible explanation is the higher fat con- centration in oats compared with barley.” Oat grain contains a higher concentration of indigestible fibre compared with barley grain, as shown by the linear increase in dietary indigestible NDF concentration and intake with increasing inclusion of oats in the current study. In the current study, complete replacement of barley with oats resulted in a linear increase in the concentration and intake of dietary crude fat (9.3 g/kg DM higher). Other studies also show that dietary fat concentration is known to display a negative relationship with enteric CH4


emissions. They added that changes in ru- emissions, rumen


fermentation, diet digestibility, milk production, and energy utilisation in dairy cows fed a grass silage-based diet. Sixteen lactating Nordic Red dairy cows received a total mixed ration [58:42 forage:concentrate on a dry matter (DM) basis]. Grass silage (Phleum pratense) was the sole forage, with canola meal (10% of diet DM) as a protein supplement. The grain


12 ▶ ALL ABOUT FEED | Volume 29, No. 7, 2021


men fermentation patterns do not explain the differences in CH4


emissions in this study, because the molar proportions of VFA were not affected by the replacement of barley.


Rumen fermentation VFA produced by fermentation of organic matter in the ru- men can have a major effect on production and product composition in ruminants. The relative proportions in which


emis-


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