Influence of ruminal methane on digesta retention and digestive physiology in non-lactating dairy cattle

Abstract

Enteric methane (CH 4 ) production is a side-effect of herbivore digestion, but it is unknown whether CH 4 itself influences digestive physiology. We investigated the effect of adding CH 4 to, or reducing it in, the reticulorumen (RR) in a 4 × 4 Latin square experiment with rumen-fistulated, non-lactating cows, with four treatments: (i) control, (ii) insufflation of CH 4 (iCH 4 ), (iii) N via rumen fistula, (iv) reduction of CH 4 via administration of bromochloromethane (BCM). DM intake (DMI), apparent total tract digestibility, digesta mean retention times (MRT), rumen motility and chewing activity, spot breath CH 4 emission (CH 4 exhal, litre/kg DMI) as well as CH 4 dissolved in rumen fluid (CH 4 RRf, µg/ml) were measured. Data were analysed using mixed models, including treatment (or, alternatively, CH 4 exhal or CH 4 RRf) and DMI relative to body mass 0·85 (rDMI) as covariates. rDMI was the lowest on the BCM treatment. CH 4 exhal was highest for iCH 4 and lowest for BCM treatments, whereas only BCM affected (reduced) CH 4 RRf. After adjusting for rDMI, CH 4 RRf had a negative association with MRT in the gastrointestinal tract but not in the RR, and negative associations with fibre digestibility and measures of rumination activity. Adjusting for rDMI, CH 4 exhal had additionally a negative association with particle MRT in the RR and a positive association with rumen motility. Thus, higher rumen levels of CH 4 (CH 4 exhal or CH 4 RRf) were associated with shorter MRT and increased motility. These findings are tentatively interpreted as a feedback mechanism in the ruminant digestive tract that aims at mitigating CH 4 losses by shortening MRT at higher CH 4 .

Review: Comparative methane production in mammalian herbivores

“…When manipulating digesta retention by other means than varying intake, namely by the addition of weights into the rumen, a shorter retention time in the rumen was correspondingly associated with a lower CH 4 production (Okine et al, 1989). On the other hand, when manipulating the CH 4 available in the rumen and accounting for variation in food intake in a cross-over study, a higher presence of CH 4 was associated with shorter retention and increased motility, possibly indicating a mechanism that aims at keeping losses at bay (Dittmann et al, 2016). These findings apparently contradict those made in monogastrics.…”

“…In ruminants, the absence of methanogens in gnotobiotically raised animals (Fonty et al, 2007), or the chemical inhibition of methanogenesis, do not appear to have evident negative effects. Although on roughage diets food intake may be reduced, this does not translate into BM losses, but may, on the contrary, be linked with higher feed conversion efficiency (McCrabb et al, 1997;Hristov et al, 2015;Dittmann et al, 2016). However, natural variation in residual BM gain or residual feed efficiency was not related to CH 4 production (Freetly et al, 2015;McDonnell et al, 2016;Alemu et al, 2017), and selection for high feeding efficiency might even be associated with increased CH 4 yields (Flay et al, 2019).…”

Kinetics of solutes and particles of different size in the digestive tract of cattle of 0.5–10 years of age, and relationships with methane production

“…Actually, phenotypic differences in digesta retention are considered a major reason for phenotypic differences in methane emission in sheep (Pinares-Patiño et al, 2013). In cattle, experimentally manipulating RR digesta kinetics modulates methane emissions (Okine, Mathison, & Hardin, 1989a), but on the other hand, manipulating RR methane concentrations modulates digesta retention (Dittmann et al, 2016). Phenotypic differences in methane emission exist in cattle (Donoghue, Bird-Gardiner, Arthur, Herd, & Hegarty, 2016), but the existence of phenotypic differences in digesta kinetics has rarely been investigated systematically.…”

Ingestive mastication in horses resembles rumination but not ingestive mastication in cattle and camels

“…In the course of the preparation for an experiment with cattle (Dittmann et al., ), the first author (MTD) tested a chew‐monitoring head collar operating with a noseband sensor (RumiWatch; Itin + Hoch GmbH, Liestal, Switzerland) on a horse for practicing halter application and data evaluation functions. The system had been developed primarily for cattle (Ruuska, Kajava, Mughal, Zehner, & Mononen, ; Zehner, Umstätter, Niederhauser, & Schick, ) but in the meantime was also validated for application in horses (Werner, Umstatter, Zehner, Niederhauser, & Schick, ).…”

“…In the course of the preparation for an experiment with cattle (Dittmann et al, 2016), the first author (MTD) tested a chewmonitoring head collar operating with a noseband sensor (RumiWatch;…”