Growth performance, rumen fermentation, bacteria composition, and gene expressions involved in intracellular pH regulation of rumen epithelium in finishing Hu lambs differing in residual feed intake phenotype1

Abstract

The objective of this study was to evaluate the effect of residual feed intake (RFI) on rumen function in finishing lambs. A total of 60 male Hu lambs (average initial BW = 25.2 ± 2.5kg) were used and were offered a pelleted high-concentrate diet, of which the forage to concentrate ratio was 25:75. Individual feed intake was recorded over a period of 42 d, then 10 lambs with the lowest RFI and the highest RFI were selected, respectively. The rumen fluid used for fermentation variables and relative abundance of bacteria measurement was obtained on d 10 and 20 after RFI measurement. At the end of this experiment, the selected lambs were slaughtered and rumen epithelium and liver tissues were collected for RNA extraction. Low-RFI lambs had lower ( < 0.01) DMI and greater ( < 0.05) G:F than the high-RFI ones, while the RFI groups did not differ in ADG and BW ( > 0.05). Additionally, RFI was positively ( = 0.57; < 0.01) correlated with DMI and negatively ( = -0.53; < 0.05) correlated with G:F. Total VFA and individual VFA decreased ( < 0.05) over time. The concentrations of total VFA, acetate, valerate, isobutyrate, isovalerate, and rumen pH ( > 0.05) were not affected by RFI classification. Nonetheless, low-RFI group lambs had a greater ( < 0.05) concentration of propionate, a lower ( < 0.05) concentration of butyrate, and a lower ( < 0.05) acetate to propionate ratio compared with the high-RFI group. There was a significant ( < 0.05) effect of RFI on the relative abundance of and . The relative abundance of , , and decreased ( < 0.05) over time in high-RFI group. And the relative abundance of in high-RFI group was greater ( < 0.05) than its low-RFI counterpart. Furthermore, RFI had no effect ( > 0.05) on gene expression associated with intracellular pH regulation (, , , , , , , and ) in rumen epithelium and β-hydroxybutyrate metabolism () in both rumen epithelium and liver tissues. In conclusion, even though low-RFI lambs had lower DMI, however, the number of was lower. Additionally, there was no difference in gene expressions level associated with intracellular pH regulation in rumen epithelium between RFI groups.

Nitrogen partitioning and microbial protein synthesis in lactating dairy cows with different phenotypic residual feed intake

“…Though low RFI cows consumed less DM, their total VFA concentrations and ruminal pH are similar to those in high RFI group, which is consistent with other results [10, 31, 34]. However, Guan et al [35] reported that more efficient steers tended to have a greater concentration of total VFA and butyrate compared with less efficient cattle.…”

Residual feed intake in beef cattle and its association with carcass traits, ruminal solid-fraction bacteria, and epithelium gene expression

“…Several lines of evidence indicate that the most-efficient cattle and sheep have greater butyrate, propionate, and propionate:acetate ratio in the rumen [ 7 , 43 ]. Enhancing the production of butyrate and propionate in the rumen is of physiologic significance for increasing energy retention from the feed since butyrate is metabolized by the ruminal epithelium to BHBA, whereas propionate is the main precursor for hepatic gluconeogenesis [ 44 , 45 ].…”

“…For example, compared with the least-efficient, the most-efficient Brahman bulls had greater abundance of Bacteroidales but lower Prevotella [ 6 ]. In a recent study, Liang et al [ 7 ] reported that the most-efficient lambs had lower Butyrivibrio fibrisolvens and Escherichia coli . The association between feed efficiency in beef cattle and changes in ruminal epithelium gene transcription was addressed recently.…”

Effects of supplementation of nonforage fiber source in diets with different starch levels on growth performance, rumen fermentation, nutrient digestion, and microbial flora of Hu lambs

“…The rumen fluid samples were thawed at room temperature to be centrifuged at 2,500 × g at 4°C for 5 min, and the supernatants were processed as described by ( Liang et al, 2017 ). VFA concentrations were determined by gas chromatography (TRACE 1300, Thermo Scientific, Milan, Italy).…”

“…The relative abundances of rumen bacteria were expressed as a proportion of total rumen bacterial 16S rRNA according to the equation: relative quantification = , where represents the threshold cycle ( Chen et al, 2008 ). Before statistical analysis, the percentage of each microbe target was calculated as ( ) × 100, and the data were log10 transformed before statistical analysis ( Liang et al, 2017 ). The level of significance was set as P ≤ 0.05 and tendencies were considered when 0.05 < P < 0.10.…”