Dietary nitrate supplementation reduces methane emission in beef cattle fed sugarcane-based diets1

Abstract

The objective of this study was to determine the effect of dietary nitrate on methane emission and rumen fermentation parameters in Nellore × Guzera (Bos indicus) beef cattle fed a sugarcane based diet. The experiment was conducted with 16 steers weighing 283 ± 49 kg (mean ± SD), 6 rumen cannulated and 10 intact steers, in a cross-over design. The animals were blocked according to BW and presence or absence of rumen cannula and randomly allocated to either the nitrate diet (22 g nitrate/kg DM) or the control diet made isonitrogenous by the addition of urea. The diets consisted of freshly chopped sugarcane and concentrate (60:40 on DM basis), fed as a mixed ration. A 16-d adaptation period was used to allow the rumen microbes to adapt to dietary nitrate. Methane emission was measured using the sulfur hexafluoride tracer technique. Dry matter intake (P = 0.09) tended to be less when nitrate was present in the diet compared with the control, 6.60 and 7.05 kg/d DMI, respectively. The daily methane production was reduced (P < 0.01) by 32% when steers were fed the nitrate diet (85 g/d) compared with the urea diet (125 g/d). Methane emission per kilogram DMI was 27% less (P < 0.01) on the nitrate diet (13.3 g methane/kg DMI) than on the control diet (18.2 g methane/kg DMI). Methane losses as a fraction of gross energy intake (GEI) were less (P < 0.01) on the nitrate diet (4.2% of GEI) than on the control diet (5.9% of GEI). Nitrate mitigated enteric methane production by 87% of the theoretical potential. The rumen fluid ammonia-nitrogen (NH(3)-N()) concentration was significantly greater (P < 0.05) for the nitrate diet. The total concentration of VFA was not affected (P = 0.61) by nitrate in the diet, while the proportion of acetic acid tended to be greater (P = 0.09), propionic acid less (P = 0.06) and acetate/propionate ratio tended to be greater (P = 0.06) for the nitrate diet. Dietary nitrate reduced enteric methane emission in beef cattle fed sugarcane based diet.

Impact of adding nitrate or increasing the lipid content of two contrasting diets on blood methaemoglobin and performance of two breeds of finishing beef steers

“…No individual MetHb measurement was >15% of total Hb which was substantially <30% total Hb, the value associated with clinical symptoms of methaemoglobinemia (Bruning-Fann and Kaneene, 1993). This agrees with most studies in which animals were adapted slowly to dietary nitrate by increasing nitrate intakes over a period of weeks (cattle:, Hulshof et al, 2012;Van Zijderveld et al, 2011 andsheep: Li et al, 2012;Van Zijderveld et al, 2010). Slow adaptation to dietary nitrate allows the rate of reduction of nitrite to ammonia by the rumen microflora to increase and prevents accumulation of nitrite in the rumen and absorption from the rumen and thereby avoids conversion of haemoglobin to MetHb (Lee and Beauchemin, 2014).…”

“…However, a comprehensive review by Bruning-Fann and Kaneene (1993) reported a reduction in feed intake when nitrate was included in the diet at 10 g nitrate/kg DM (cattle) and 30 g nitrate/kg DM (sheep). In agreement, Hulshof et al (2012) reported a tendency for calcium nitrate (fed at 22 g nitrate/kg DM) to reduce DMI by 6% in beef cattle fed a sugarcane-based diet. In contrast, Sangkhom et al (2012) reported improved growth rates and feed conversion efficiency in growing cattle when potassium nitrate (fed at C-A.…”

“…The reduction of nitrate to nitrite and then to ammonium provides an energetically more favourable route for disposal of metabolic hydrogen produced during fermentation of feed carbohydrates in the rumen than the production of CH 4 . Although nitrate has been shown in many studies to reduce CH 4 emissions from ruminants (Nolan et al, 2010;Van Zijderveld et al, 2010 andHulshof et al, 2012;Li et al, 2012), the potential for its use has been hindered due to the toxicity of the intermediate product (nitrite). In the rumen, microbes rapidly reduce nitrate to nitrite and then reduce nitrite to ammonia.…”

Technical options for the mitigation of direct methane and nitrous oxide emissions from livestock: a review

“…Recent research on sheep (Sar et al, 2004;Nolan et al, 2010;van Zijderveld et al, 2010) and cattle (van Zijderveld et al, 2011a and2011b;Hulshof et al, 2012) has shown promising results with nitrates decreasing enteric CH 4 production by up to 50%. Nitrates may be particularly attractive in developing countries where forages contain negligible levels of nitrate and insufficient CP for maintaining animal production.…”

Is there a relationship between genetic merit and enteric methane emission rate of lactating Holstein-Friesian dairy cows?

“…During the last two decades, calorimeter data from research institutes has been used to develop a range of prediction models to facilitate an improved understanding of the effects of diet and animal factors on enteric CH 4 emissions (Mills et al, 2003;Yan et al, 2010;Ellis et al, 2012). In addition, many nutritional strategies designed to reduce CH 4 emissions at an individual animal basis have been evaluated, including the use of dietary manipulation (e.g., improving forage quality, inclusion of concentrates, feed processing) and dietary additives (e.g., inhibitors, electron receptors, ionophores, plant bioactive compounds) (Hulshof et al, 2012;Hristov et al, 2013;Ramin and Huhtanen, 2013). Although some of these 'additive' and 'biotechnological' approaches are promising, their long-term effects have not yet been extensively established.…”