Submitted to: Journal of Animal Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/12/2008
Publication Date: 6/1/2008
Citation: Farran, T.B., Reinhardt, C.D., Blasi, D.A., Minton, J.E., Elsasser, T.H., Higgins, J.J., Drouillard, J.S. 2008. Source of dietary lipid may modify the immune response in stressed feeder cattle. Journal of Animal Science. 86:1382-1394. Interpretive Summary: A study was conducted at Kansas State University to evaluate whether a nutrition-based strategy could be developed which would improve the health status of cattle and defend against the ill effects of invading microbes. The objective of the study was to compare the effects of diets rich in omega-3 fatty acids versus omega-6 fatty acids on differences in health status and growth performance of steers. The content of dietary omega-3 or omega-6 fatty acids was enriched in a diet by adding either flax seed or soy beans and tallow, respectively. The results of several feeding trials determined that diets rich in omega-6 fatty acids had a slight but significant increased production of immune responses consistent with a state of proinflammatory stress while diets rich in omega-3 fatty acids yielded opposite results. The studies are important to the beef production industry in that they indicate how the composition of unsaturated omega fatty acids in diets fed to cattle might impact some parameters of immune function which further may play a significant role in the economic impact of disease stress.
Technical Abstract: Five studies were conducted to evaluate the effects of lipid source on performance and health. A total of 332 heifers (195 ± 2.37 kg initial BW) in Trial 1 and 336 heifers (206 ± 1.70 kg initial BW) in Trial 2 were fed diets containing ground flaxseed (FLAX), rolled full-fat soybeans (SOY), or tallow (TAL) at 13, 20, or 4%, respectively (DM basis). All diets were formulated to be iso-nitrogenous and iso-caloric. The ADG and feed efficiency for the first 7 d and for the entire feeding period were greater (P < 0.05) for TAL and FLAX than for SOY. Percentage of animals treated and re-treated for bovine respiratory disease did not differ among dietary treatments. The FLAX treatment increased (P < 0.05) total n-3 polyunsaturated fatty acid (PUFA) concentrations in the plasma, whereas SOY increased (P < 0.05) plasma concentrations of total n-6 PUFA. In Trial 3, 18 steers were individually fed diets containing tallow (TAL) and 18 steers were fed a diet containing rolled full-fat soybeans (SOY; 20% of DM). In Trials 4 and 5, 18 steers were individually fed diets containing tallow (TAL) and 18 steers were fed diets containing ground flaxseed (FLAX; 12.9% of DM). On d 14 and 17 of study 3, 4, and 5, 16 steers from each dietary treatment were injected i.v. with E. coli O55:B5 lipopolysaccharide (LPS), and 2 steers from each diet were injected with saline. Rectal temperatures after LPS challenges were lower (P < 0.05) for SOY and FLAX than for TAL, and plasma TNF was greater (P < 0.05) for SOY than for TAL. Serum haptoglobin and blood fibrinogen increased and white blood cell count decreased in response to LPS, but none of these variables were affected by treatment. Although this research failed to measure a response of lipid source on feedlot morbidity or mortality, these studies indicate that altering the source and type of dietary fatty acids may modify the immune response in stressed feeder cattle, and that performance may be hindered by feeding full-fat soybeans to receiving cattle.