Effect of dietary forage to concentrate ratio on volatile fatty acid absorption and the expression of genes related to volatile fatty acid absorption and metabolism in ruminal tissue

Abstract

The objective of the study was to investigate the fractional rate of volatile fatty acid (VFA) absorption and the expression of genes encoding for transporters and enzymes involved in the absorption and metabolism of VFA in ruminal tissue when cattle were fed high or low concentrate diets. Twelve ruminally cannulated Holstein cows were used in a randomized complete block design. The low concentrate (LC) and high concentrate (HC) diets contained 8 and 64% dietary concentrate (dry matter basis), respectively. Cows were fed their respective diet for at least 28 d, following which data and samples were collected over 6 d. Ruminal pH was measured continuously for 72 h, and the in vivo VFA absorption and passage rates were measured using Co-EDTA and n-valeric acid as markers. Ruminal tissue was collected postslaughter from the ventral sac of the rumen, and gene expression was evaluated using quantitative real-time PCR. Dry matter intake was not affected by treatment, averaging 14.9 kg/d, but cows fed HC had lower mean ruminal pH (6.03 vs. 6.48), and a greater duration (376 vs. 10 min/d) that ruminal pH was <5.8. Ruminal VFA concentration was 24 mM higher for cows fed HC compared with LC; however, the fractional rate of VFA absorption and passage from the rumen was not affected by dietary treatment, averaging 23.4 and 9.6%/h, respectively. The expression of genes encoding for enzymes involved in VFA activation and ketogenesis were not affected by treatment. Cows fed HC tended to have a relative abundance of pyruvate dehydrogenase lipoamide alpha 1 mRNA transcripts that was 1.4 times lower than that of cows fed LC, but other enzymes involved in pyruvate metabolism or regulation of the citric acid cycle were not affected. Collectively, these results suggest that the dietary forage to concentrate ratio does not affect the fractional rate of VFA absorption in vivo, but potentially alters energy metabolism in ruminal tissue.

Identification of differentially expressed proteins in ruminal epithelium in response to a concentrate-supplemented diet

“…The response of the ruminal epithelium to an increase of energy (and protein) has been previously studied in sheep, cattle, and goats (19,47,55).…”

“…Hence, supplementation of forage-fed ruminants with sufficient amounts of energy and protein is necessary and significantly improves milk production or daily weight gain (41), but, particularly, a surplus of easily fermented carbohydrates or low-fiber intake will place the animals at risk. Such a change in the diet is a challenge for rumen microbes (31) and especially for the ruminal epithelium with respect to adaptation to the new fermentation pattern (47,55). Insufficient adaptation to diet may result in disintegration of the epithelium (22), translocation of lipopolysaccharides (30), and disturbed transport mechanisms (22) and can further cause subacute ruminal acidosis (14, 49).…”

“…In particular, feeding a diet containing highconcentrate rations increases the number and/or size of papillae in the rumen and influences the transport properties of the ruminal epithelium (19,26). Furthermore, a diet rich in concentrate increases short-chain fatty acid (SCFA) concentration and leads to a decrease of pH (47).…”

Effect of grain type and processing method on rumen fermentation and milk rumenic acid production

“…Furthermore, rumen availability and degradability of grain starch can be increased by processing grain (Hale, 1973;Theurer, 1986). Previous studies have shown that the feeding of grain-based diets decreases rumen pH (Yang and Beauchemin, 2007;Penner et al, 2009). In most studies, rumen pH measurements were generally taken either once (Tajima et al, 2001), twice (Abughazaleh et al, 2003;Mohammed et al, 2009), four times (Klieve et al, 2003) or six times a day (Kalscheur et al, 1997;Kim et al, 2008).…”

Nutrient digestibility and rumen fermentation of Thai native purebred compared with Thai native x Lowline Angus crossbred beef cattle

“…Supplementation of diet that contains high proportion of NFC possibly led to an increase in VFA production. Penner et al (2009) illustrated that production of VFA especially propionic acid can be induced by concentrate supplementation. Dehority (2003) also stated that supplying of NFC is able to stimulate VFA synthesis particularly propionic acid.…”