Ruminal volatile fatty acid absorption is affected by elevated ambient temperature

Abstract

The objective of this study was to investigate the effect of short-term elevated ambient temperature on ruminal volatile fatty acid (VfA) dynamics and rumen epithelium gene expression associated with the transport and metabolism of VFA. Eight ruminally cannulated Holstein heifers (200 kg) were used in a factorial, repeated measures experiment with two treatments and two periods. During the first period, animals were provided with feed ad libitum and housed at 20 °C. During the second period, one group (HS) was housed at 30 °C and fed ad libitum. The other group (PF) was housed at 20 °C and pair-fed to match the intake of the HS group. During each period, animals were kept on treatment for 10 day, with sample collection on the final day. In the second period, indicators of heat stress were significantly different between PF and HS animals (P < 0.05). There was a thermal environment effect on butyrate production (P < 0.01) that was not associated with feed intake (P = 0.43). Butyrate absorption decreased in HS animals (P < 0.05) but increased in PF animals (P < 0.05) from period 1 to period 2. There was a feed intake effect on BHD1 expression (P = 0.04) and a tendency for a thermal environment effect (P = 0.08), with expression increasing in both cases. Expression of MCT4 was affected by feed intake (P = 0.003) as were all NHE genes (NHE1, NHE2, and NHE3; P < 0.05). These results indicate that with low feed intake and heat stress, there are shifts in rumen VfA dynamics and in the capacity of the rumen epithelium to absorb and transport VfA. Climate change is a notable barrier to improving livestock sustainability because it may increase the incidence of heat stress (HS) 1. Heat stress costs the U.S. livestock industries $1.7 billion annually 2, and leads to reduced growth rate 3, milk production 4, and reproductive efficiency 5,6 in dairy cattle. Much of the loss in productivity is associated with reduced feed intake 7,8 and increased maintenance energy 9. Another key change that occurs during heat stress is that animals become insulin resistant and fail to mobilize body fat, favoring breakdown of muscle as means to obtain additional energy 10,11. Although these shifts in post-absorptive metabolism have been well characterized in heat stressed cattle, changes in nutrient digestion and absorption have not been evaluated comprehensively. Multiple studies have shown changes in VFA concentrations related to rumen metabolism during heat stress 12-15 , which could be partially driven by a shift in intake. That being said, it is known that concentrations alone are not true representations of metabolism. In particular, absorbed volatile fatty acid (VFA) profiles may be implicated in the post-absorptive shifts in metabolism observed during heat stress because VFA have been shown to influence insulin sensitivity in monogastrics 16,17. It is not unreasonable to think that a similar physiological response may also occur in ruminants. We hypothesize that during exposure to elevated ambient temperature (HS treatment), shifts in ...

Seasonal Influence on Rumen Microbiota, Rumen Fermentation, and Enteric Methane Emissions of Holstein and Jersey Steers under the Same Total Mixed Ration

“…Earlier studies also reported a significant decrease in VFA production during heat stress conditions [ 59 , 60 , 61 ]. In contrast, butyrate absorption through the rumen epithelium could greatly decrease under heat stress [ 62 ], which corroborates the significantly higher butyrate concentration observed in the present study during high THI in summer. Both seasons and breeds also had a significant influence on the A:P ratio.…”

Evaluation of microwave-dried black soldier fly (Hermetia illucens) larvae meal as a dietary protein source in broiler chicken diets

“…Increased VFA levels are also related to feed intake via the control of satiety and hunger, as it has been reported that elevated propionate levels reduce eating behaviour by affecting satiety through brain striatal pathways (Bedford et al, 2020;Byrne et al, 2016). Therefore, in the present study, the decreased feed intake may have been affected by the elevated caecal propionate level; infusion of propionate altered the feeding behaviour and decreased energy intake, supporting this prediction (Oba and Allen, 2003).…”

Effects of acute heat stress on salivary metabolites in growing pigs: an analysis using nuclear magnetic resonance-based metabolomics profiling

“…However, in the result of correlations of identified metabolites in pigs, there was a negative correlation between the concentrations of acetate and propionate. This result might be due to the conversion of propionate to acetate by decreased feed intake under HS condition was stronger than that of acetate to propionate [45].…”

“…Because it was previously reported that infusion of propionate decreased feed intake by affecting satiety [46]. There was also a result of interconversion between acetate and propionate by the HS [45]. However, in the result of correlations of identified metabolites in pigs, there was a negative correlation between the concentrations of acetate and propionate.…”

“…Concentrations of volatile fatty acids (VFAs) such as acetate, propionate, and butyrate are related to reduced feed intake by HS. Especially, Bedford et al [45] reported that the absorption and production of the VFAs are associated with controlling both satiety and hunger. In the present study, it can be speculated that reduced feed intake by HS decreased production and increased absorption of both acetate and propionate.…”