Methane emissions by dairy cows fed increasing proportions of white clover (Trifolium repens) in pasture

Abstract

Methane (CH4) production from ruminant digestion has a significant impact on the New Zealand greenhouse gas (GHG) inventory and represents a loss of about 10% of metabolisable energy (ME) intake. Previous trials with sheep and cattle have demonstrated significantly lower methane losses per unit feed intake from legumes compared to grass dominant pasture. Most trials have compared forages fed as sole diets but white clover (Trifolium repens) is usually fed with perennial ryegrass (Lolium perenne) as a mixed pasture, as it complements ryegrass for animal production. An indoor feeding trial was conducted in December 2003 with thirty-two Holstein-Friesian dairy cows in mid-lactation to determine effects of increasing proportions of white clover on methane emissions and cow performance. Cows were housed indoors and fed perennial ryegrass with 0, 15, 30 or 60% white clover ad libitum on a dry matter (DM) basis. Increasing proportions of white clover resulted in linear increases in dry matter intakes (DMI) and reductions in methane per kg DM eaten, although the extent to which CH4 production/kg DMI was lowered was less than anticipated from previous measurements from sheep fed white clover as a sole diet. DMI of cows fed 60% white clover was 20.5 vs. 15.6 kg DM/cow/day for 100% perennial ryegrass (P

Milk production and enteric methane emissions by dairy cows grazing fertilized perennial ryegrass pasture with or without inclusion of white clover

“…However, the results agree with van Dorland et al (2007), who reported no difference in percow CH 4 emissions between cows fed GO and GWc (0.4 clover content) silages. Similar to our findings, previous studies have not found differences in the milk-related CH 4 emission variables between similar fresh forages (Lee et al, 2004) or silage diets (van Dorland et al, 2007). In the current experiment, cows grazing GWc swards had slightly greater DMI than the GO cows, yet GWc cows produced 11.9% less CH 4 /kg of DMI (CH 4 yield) than the GO cows, which is greater than the 9.6% difference between sward types reported by Lee et al (2004).…”

“…Similar to our findings, previous studies have not found differences in the milk-related CH 4 emission variables between similar fresh forages (Lee et al, 2004) or silage diets (van Dorland et al, 2007). In the current experiment, cows grazing GWc swards had slightly greater DMI than the GO cows, yet GWc cows produced 11.9% less CH 4 /kg of DMI (CH 4 yield) than the GO cows, which is greater than the 9.6% difference between sward types reported by Lee et al (2004). Lee et al (2004) found greater differences in CH 4 per unit of feed intake between the 2 groups when the clover content of the GWc diet was increased.…”

“…The per-cow CH 4 emissions and the CH 4 emissions per unit of feed intake estimated in this experiment are within the range of values reported for dairy cows offered comparable fresh forages (Ulyatt et al, 2002;Lee et al, 2004) and silages (van Dorland et al, 2007). The similar daily CH 4 emissions between the 2 treatments contrast with previous indoor studies that found lower CH 4 emission per cow when animals were offered GO compared with when cows were offered GWc mixtures with different clover contents ranging from 0.15 to 0.6 (Lee et al, 2004). However, the results agree with van Dorland et al (2007), who reported no difference in percow CH 4 emissions between cows fed GO and GWc (0.4 clover content) silages.…”

“…In the current experiment, cows grazing GWc swards had slightly greater DMI than the GO cows, yet GWc cows produced 11.9% less CH 4 /kg of DMI (CH 4 yield) than the GO cows, which is greater than the 9.6% difference between sward types reported by Lee et al (2004). Lee et al (2004) found greater differences in CH 4 per unit of feed intake between the 2 groups when the clover content of the GWc diet was increased. The lower CH 4 emissions per unit of feed intake for the GWc cows compared with the GO cows can be attributed to 2 factors: (1) the digestibility characteristics that clover confer on the pasture and differences between clover and grass during the digestion process (clover has lower fiber content, higher in vitro digestibility, and faster rumen passage rate; Moe and Tyrrell, 1979;Pinares-Patiño et al, 2003;Beauchemin et al, 2008), greater VFA content, and the lower ratio of acetic:propionic FA that the clover fermentation process produces compared with PRG (Beever et al, 1986;Purcell et al, 2012); and (2) the increased DMI (Moe and Tyrrell, 1979;Ulyatt et al, 2002;Pinares-Patino et al, 2009) that the legumes can promote when added to GO pasture.…”

“…Methane emissions related to gross energy intake of animals fed legumes are lower than animals fed grasses (Waghorn et al, 2006;Beauchemin et al, 2008). However, although some work has shown that clover inclusion in pasture can reduce dairy cow CH 4 emissions (Lee et al, 2004) others have found no effects (van Dorland et al, 2007).…”