Feed restriction reduces short-chain fatty acid absorption across the reticulorumen of beef cattle independent of diet1

Abstract

The objective of this study was to evaluate the effects of the forage-to-concentrate ratio (F:C) of diets fed before and during short-term feed restriction (FR) on rumen fermentation, absorptive capacity of the reticulorumen, and apparent total tract digestibility. Twenty ovariectomized and ruminally cannulated Angus × Hereford heifers were blocked by BW and individually penned in box stalls (9 m(2)), having free access to water throughout the study. Heifers were randomly assigned to 1 of 2 dietary treatments, receiving either a high forage diet (HF; F:C of 92:8) or a moderate forage diet (MF; F:C of 60:40). Diets were fed ad libitum for 14 d before 5 d of baseline measurements (BASE) followed by 5 d of FR where heifers were restricted to 25% of ad libitum DMI relative to BASE. Dry matter intake was measured daily and ruminal pH was recorded every 2 min throughout the study. Ruminal fluid and blood samples were collected on d 3 of BASE and FR whereas short-chain fatty acid (SCFA) absorption was assessed in vivo using the isolated washed reticulorumen technique on d 5 of BASE and FR. Indigestible NDF was used as a marker to estimate apparent total tract digestibility. Diet × period interactions (P = 0.030 and 0.025) were detected for DMI and ruminal SCFA concentration, respectively. The interaction was the result of greater DMI and numerically greater SCFA concentration for MF than HF during BASE, with a reduction observed for both during FR, although treatment effects were no longer present. Period effects (BASE vs. FR) but not treatment effects (P > 0.05) were detected for mean ruminal pH (P < 0.001) and the total SCFA absorption rate (mmol/h; P = 0.038). During BASE, mean pH was reduced (6.4 vs. 6.9) and the SCFA absorption rate was greater relative to FR (674.5 vs. 554.8 mmol/h). Diet (P < 0.001) and period (P < 0.001) effects were detected for DM and OM digestibility with greater digestibility occurring for heifers fed MF than HF (70.5 vs. 63.3% for DM and 73.0 vs. 66% for OM) and greater digestibility during FR than BASE (69.5 vs. 64.3% for DM and 71.7 vs. 67.2% for OM). During FR, NDF digestibility was also greater than during BASE (P < 0.001; 62.4 vs. 55.8%). The effect of FR on serum NEFA differed by diet (diet × period, P < 0.001) with NEFA being greater for heifers fed HF than MF during FR (474.4 vs. 377.7 μEq/mL, respectively) with no differences observed between HF and MF during BASE. It can be concluded that severe short-term FR had a negative impact on ruminal SCFA absorption and energy balance and that altering the F:C of the diet does not mitigate these effects.

Moderate decreases in the forage-to-concentrate ratio before feed restriction and increases thereafter independently improve the recovery from a feed restriction insult in beef cattle1

“…This is 1 of 2 papers from a single experiment designed to evaluate the effects of FR and the timeline for recovery following return to ad libitum intake when cattle were fed diets differing in the F:C. The focus of the present paper is to evaluate the recovery response on return to ad libitum intake following FR with the companion paper (Albornoz et al, 2013) describing the effects related directly to the FR period, including effects on DMI, ruminal fermentation, and SCFA absorption in response to differing dietary F:C. The experiment was conducted from May to September 2011. Throughout the study, heifers were individually housed in box stall pens (9 m 2 ) at the University of Saskatchewan Livestock Research Building and were cared for in accordance to the guidelines of the Canadian Council on Animal Care (2009).…”

“…Within block, heifers were fed the high forage diet (HF; F:C = 92:8; Table 1) or the moderate forage diet (MF; F:C = 60:40; Table 1) before (for 19 d) and during the 5-d FR period (PRE). The actual DMI consumed during FR equated to 24.9 and 24.4% for HF and MF, respectively, relative to that measured during a 5-d baseline period (Albornoz et al, 2013). Following PRE, half of the heifers from each PRE treatment were assigned to the HF or MF diet for the duration of the 3 wk recovery period (designated as REC1, REC2, and REC3 and collectively as POST) and were fed ad libitum.…”

“…In beef and dairy production, limited access to feed or voluntary reductions in feed intake occur and result in negative effects on growth performance (Arthington et al, 2008;Pritchard and Mendez, 1990) and milk production (Rhoads et al, 2009). While severe short-term feed restriction (FR) is associated with a reduction in energy intake, recent studies have further demonstrated that short-term feed deprivation (Gäbel et al, 1993) and short-term FR decrease short-chain fatty acid (SCFA) absorption across the reticuloruminal epithelium (Zhang et al, 2013a;Albornoz et al, 2013), decreases rumen epithelial and total tract barrier function (Zhang et al, 2013a), and compromises immune function (Marques et al, 2012). Although it may not be possible to prevent FR, in many cases its occurrence is predictable as is for weaning (Gibb et al, 2000), transportation (Galyean et al, 1981;Pence et al, 2009), heat stress (West, 2003), and parturition (Grummer et al, 2004).…”

Aspects of rumen adaptation in dairy cattle : morphological, functional, and gene expression changes of the rumen papillae and changes of the rumen microbiota during the transition period

“…In addition, transition from a mixed ration to pasture has been associated with a reduction in papillae surface area and greater risk for subacute rumen acidosis . Indeed, Albornoz et al (2013) reported that 5 d of severe feed restriction (feeding 25% of voluntary feed intake) reduced k a VFA. Unfortunately, Albornoz et al (2013) did not report papillae surface area, and the decrease in k a VFA might also be explained by a reduction in epithelial blood flow (discussed below).…”

“…Indeed, Albornoz et al (2013) reported that 5 d of severe feed restriction (feeding 25% of voluntary feed intake) reduced k a VFA. Unfortunately, Albornoz et al (2013) did not report papillae surface area, and the decrease in k a VFA might also be explained by a reduction in epithelial blood flow (discussed below). Finally, considering that the majority of papillae atrophy occurs during the first weeks of the dry period, it is unlikely that a shorter dry period (van Knegsel et al, 2014) than those in the present experiments will prevent such atrophy of the rumen papillae.…”