The influence of grass silage-to-maize silage ratio and concentrate composition on methane emissions, performance and milk composition of dairy cows

Abstract

It is well-established that altering the proportion of starch and fibre in ruminant diets can alter ruminal and post-ruminal digestion, although quantitative evidence that this reduces enteric methane (CH 4 ) production in dairy cattle is lacking. The objective of this study was to examine the effect of varying grass-to-maize silage ratio (70 : 30 and 30 : 70 DM basis), offered ad libitum, with either a concentrate that was high in starch or fibre, on CH 4 production, intake, performance and milk composition of dairy cows. A total of 20 cows were allocated to one of the four experimental diets in a two-by-two factorial design run as a Latin square with each period lasting 28 days. Measurements were conducted during the final 7 days of each period. Cows offered the high maize silage ration had a higher dry matter intake (DMI), milk yield, milk energy output and lower CH 4 emissions when expressed per kg DMI and per unit of ingested gross energy, but there was no difference in total CH 4 production. Several of the milk long-chain fatty acids (FA) were affected by forage treatment with the most notable being an increase in 18:0, 18:1 c9, 18:2 c9 c12 and total mono unsaturated FA, observed in cows offered the higher inclusion of maize silage, and an increase in 18:3 c9 c12 c15 when offered the higher grass silage ration. Varying the composition of the concentrate had no effect on DMI or milk production; however, when the high-starch concentrate was fed, milk protein concentration and milk FAs, 10:0, 14:1, 15:0, 16:1, increased and 18:0 decreased. Interactions were observed for milk fat concentration, being lower in cows offered high-grass silage and high-fibre concentrates compared with the high-starch concentrate, and FA 17:0, which was the highest in milk from cows fed the high-grass silage diet supplemented with the high-starch concentrate. In conclusion, increasing the proportion of maize silage in the diets of dairy cows increased intake and performance, and reduced CH 4 production, but only when expressed on a DM or energy intake basis, whereas starch-to-fibre ratio in the concentrate had little effect on performance or CH 4 production.Keywords: methane, dairy cows, forage, SF 6 tracer ImplicationsMethane production by ruminants is becoming an increasing concern due to its contribution to greenhouse gas emissions. Dietary strategies to reduce methane production in terms of supplying dietary supplements can result in pollution swapping, and are therefore not desirable. Researchers examine the effect of changing the ratio of grass and maize silage in addition to changing the amount of starch and fibre in the concentrate. The results obtained are related to national greenhouse gas inventories and potential effects of cropping systems on greenhouse gas emissions along with animal performance. IntroductionGlobally, agriculture, forestry and land use change account for 56% of non CO 2 anthropogenic greenhouse gas emissions, with methane (CH 4 ) from enteric fermentation accounting for 36% of this (Smith et al., 2014...

Replacement of grass and maize silages with lucerne silage: effects on performance, milk fatty acid profile and digestibility in Holstein-Friesian dairy cows

“…This is, however, unlikely to explain the current results as lucerne is generally low in polyphenol oxidase. Milk C18:2 c9 c12 values were in the same range as that reported by others for grass and maize silage-based rations (Hart et al, 2015), and increased with inclusion level of lucerne, despite the highest concentration of this FA in the maize silage. The net result of these changes was a small but significant increase in the milk content of PUFA with inclusion level of lucerne.…”

“…The metabolisable energy content of the forages was determined by near IR reflectance spectroscopy (Sciantec Analytical, Selby, UK) using a system approved by the UK advisory services (Offer et al, 1996), whereas starch and neutral cellulase digestibility were determined as per Hart et al (2015). Milk samples were analysed using a Milkoscan minor spectrophotometer (Foss Ltd, Denmark) calibrated by the methods of AOAC (2000).…”

“…Grass silage has a low to moderate CP content with a mean value of 133 g/kg dry matter (DM) (s.d. 24.4;Yan and Agnew, 2004), whereas maize silage has a low CP value of approximately 68 to 105 g/kg DM Hassanat et al, 2013;Hart et al, 2015). Feeding grass silage on its own or in combination with maize silage to high-yielding dairy cows, therefore requires supplementation with purchased protein feeds to meet the cows metabolisable protein requirements (Thomas, 2004).…”

Inclusion of Yeast Cultures (<i>Saccharomyces cerevisiae</i>) to Dairy Cows’ Urea-Treated Rice Straw Diets Improves Mozzarella Cheese Processing and Yield

“…The high milk fat content obtained with UTRS diet can be related to high fibre content which stimulates acetate production, a primary precursor for milk fat synthesis in the rumen [19]. This observation concurs with the pioneer work of [20] and other recent observations [21] [22] that indicated positive association between high fibre diets with yield of milk fat content. In contrast, yeast inclusion in the high fibre diet depress acetate production as was observed with UTRS + Y diet, subsequently resulting in a drop in milk fat.…”

Dietary Fatty Acids Affect Red Blood Cell Membrane Composition and Red Blood Cell ATP Release in Dairy Cows

“…Maize silage (MS) is an important component in diets of dairy cows [19,20]. Compared to other dietary components, such as grass/maize silage (GMS), MS delivers high amounts of the n-6 FA LA but lower amounts of the n-3 FA ALA [21,22,23], which possibly modifies physiological functions. For example, the incorporation of n-3 FA in bovine corpora lutea membranes is linked with the formation of membrane lipid microdomains.…”