Effects of dehydrated lucerne and soya bean meal on milk production and composition, nutrient digestion, and methane and nitrogen losses in dairy cows receiving two different forages

Abstract

Dehydrated lucerne is used as a protein source in dairy cow rations, but little is known about the effects of lucerne on greenhouse gas production by animals. Eight Holstein dairy cows (average weight: 582 kg) were used in a replicated 4 × 4 Latin square design. They received diets based on either maize silage (M) or grass silage (G) (45% of diet on dry matter (DM) basis), with either soya bean meal (15% of diet DM) completed with beet pulp (15% of diet DM) (SP) or dehydrated lucerne (L) (30% of diet DM) as protein sources; MSP, ML, GSP and GL diets were calculated to meet energy requirements for milk production by dairy cows and degradable protein for rumen microbes. Dry matter intake (DMI) did not differ among diets (18.0 kg/day DMI); milk production was higher with SP diets than with L diets (26.0 v. 24.1 kg/day), but milk production did not vary with forage type. Milk fatty-acid (FA) composition was modified by both forage and protein sources: L and G diets resulted in less saturated FA, less linoleic acid, more trans-monounsaturated FA, and more linolenic acid than SP and M diets, respectively. Enteric methane (CH 4 ) production, measured by the SF 6 tracer method, was higher for G diets than for M diets, but did not differ with protein source. The same effects were observed when CH 4 was expressed per kg milk. Minor effects of diets on rumen fermentation pattern were observed. Manure CH 4 emissions estimated from faecal organic matter were negatively related to diet digestibility and were thus higher for L than SP diets, and higher for M than G diets; the resulting difference in total CH 4 production was small. Owing to diet formulation constraints, N intake was higher for SP than for L diets; interaction between forage type and protein source was significant for N intake. The same statistical effects were found for N in milk. Faecal and urinary N losses were determined from total faeces and urine collection. Faecal N output was lower for M than for G diets but did not differ between protein sources. Urinary N output did not differ between forage types, but was lower for cows fed L diets than for cows fed SP diets, potentially resulting in lower ammonia emissions with L diets. Replacing soya bean meal plus beet pulp with dehydrated lucerne did not change CH 4 production, but resulted in more N in faeces and less N in urine.

Methane emissions of stored manure from dairy cows fed conventional or brown midrib corn silage

“…Thus, total CH 4 emissions (sum of enteric and manure emissions) were 668 and 611 g/d for cows fed BMCS and CCS, respectively. Calculated manure CH 4 emissions of cows fed BMCS and CCS represent 30 and 21% of the total emissions, respectively, which is within the range of emissions reported in other studies (Doreau et al, 2014;Hassanat and Benchaar, 2019). Compared with CCS, feeding cows BMCS did not significantly affect enteric CH 4 emissions (−13 g/d), but increased manure CH 4 emissions by 70 g/d, resulting in a net increase in total CH 4 emissions by 57 g/d (+9%).…”

“…According to IPCC (2006), CH 4 emission factor (kg of CH 4 /cow per year) of manure management depends on quantity of volatile solids (VS) excreted and maximum CH 4 -producing capacity of manure VS (B 0 ). Diets of dairy cow have a direct effect on the amount and degradability of excreted VS (Doreau et al, 2014;Møller et al, 2014;Massé et al, 2016;Hassanat and Benchaar, 2019). Forages are the main component in dairy cow diets.…”

Additive methane-mitigating effect between linseed oil and nitrate fed to cattle1

“…Total tract di gestibility and N balance were determined from to tal and separate collection of feces and urine for 6 d during wk 4 of each experimental period. To separate urine from feces, cows were fitted with flexible pipes (Doreau et al, 2014b) connected to a 30-L flask con taining 500 mL of 3 M sulfuric acid to achieve a urine pH < 3 and thus avoid N volatilization. Feces and urine were removed once daily.…”

Substitution of corn silage with sorghum silages in lactating cow diets: In vivo methane emission and global warming potential of milk production

“…: Benchaar et al, 2014;Brask et al, 2013;Doreau et al, 2013;Hassanat et al, 2013) investigated in vivo the effect of forage type (corn, barley or grass silages) on enteric CH4 emissions and in these studies, unlike ours, diets were not balanced for NDF and starch concentrations. Despite the similar carbohydrate contents, there were differences among diets when CH4 production was expressed as CH4 per kg of DMI (P = 0.09) or as CH4 per kg of NDF intake (P = 0.02).…”