|KERN, REBECCA - University Of Wyoming|
|RULE, D - University Of Wyoming|
|LUDDEN, PAUL - University Of Wyoming|
Submitted to: Livestock Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/22/2016
Publication Date: 3/2/2016
Publication URL: http://handle.nal.usda.gov/10113/62040
Citation: Kern, R.J., Lindholm-Perry, A.K., Freetly, H.C., Kuehn, L.A., Rule, D.C., Ludden, P.A. 2016. Rumen papillae morphology of beef steers relative to gain and feed intake and the association of volatile fatty acids with kallikrein gene expression. Livestock Science. 187:24-30.
Interpretive Summary: The largest cost involved in beef production is the cost to feed the animal; therefore, improving upon the ability of cattle to utilize feed to produce meat product (feed efficiency would reduce the cost of beef production. The lining of the first compartment of the cattle stomach (rumen) is lined with small tongue like projections (papillae) which are involved in the digestion, absorption and utilization of key nutrients including volatile fatty acids (VFA). Feed efficiency data was collected on 48 beef steers. Papillae were measured for length, width, and the number of papillae occupying 1cm squared of stomach lining. Surface area of the stomach lining was calculated from these measurements. These physical attributes were tested for correlation with feed efficiency traits. None of the papillae parameters were correlated with feed efficiency traits. Rumen fluid was collected from 15 steers and VFAs were measured. None of the VFAs were correlated with feed efficiency traits. Transcript abundances of kallikrein (KLK) genes have previously been associated with rumen concentrations of a VFA (butyrate) as well as feed efficiency. The transcript abundances of KLK genes were evaluated in 16 of the steers. Abundance of KLK5, 10, 12 was correlated with VFA concentrations in the rumen and abundance of KLK9 and 10 were correlated with gain. Our results indicate that a relationship may exist between the KLK genes, VFA environment in the rumen and average daily gain of the beef steer.
Technical Abstract: Feed costs are the most expensive input in beef production. Improvement in the feed efficiency of beef cattle would lower feed inputs and reduce the cost of production. The rumen epithelium is responsible for absorption and metabolism of nutrients and microbial by-products, and may play a significant role in feed efficiency. Our objective was to determine the relationships among rumen papillae morphology, gene expression, volatile fatty acid concentrations, and feed efficiency. Average daily gain (ADG) and average daily feed intake (ADFI) data were collected on a crossbred population of beef steers over three feeding trials. Based on feed intake and weight gain differences, 48 steers were selected for the project (16 from each feeding trial). At harvest, rumen epithelial samples were taken from three locations in the rumen of each animal. The number of papillae on 1 cm2 of epithelium was counted to determine density. Papillae (n = 30) from each sample were measured for length and width. The density, length, and width were combined to determine surface enlargement factor (SEF). None of the morphological characteristics of the papillae (length, width, density or SEF) were associated with feed intake or gain (P > 0.10). Ruminal fluid was collected from steers (n = 15) in the third trial for volatile fatty acid (VFA) analysis. No differences in volatile fatty acid (VFA) concentrations were associated (P > 0.165) with ADFI or ADG. Ruminal butyrate concentrations have previously been associated with the transcript abundance of kallikrein (KLK) genes. Additionally, an unpublished discovery study found KLK10 to be differentially expressed in our first trial of steers with divergent ADG and ADFI phenotypes. Thus, we evaluated the transcript abundance of KLK5, 6, 7, 8, 9, 10, 12, and 13 in rumen papillae from steers in the third trial, and found that expression levels of KLK5, 10 and 12 were correlated with VFA concentrations in the rumen (P < 0.05), and expression levels of KLK9 and 10 were associated with gain. While rumen papillae morphology was not associated with beef steer gain or intake, our data supports previous evidence that members of the kallikrein gene family have a relationship with ADG, as well as the VFA environment in the rumen.