THE use of antibody preparations from avian origin has been proposed as an alternative feed additive to mitigate ruminal acidosis and improve ruminal health in both feedlot and dairy diets (DiLorenzo et al., 2006, 2007, 2008; Blanch et al., 2009).
The rationale is that by immunizing laying hens with a desired antigen (e.g., whole-cell ruminal microorganisms or fractions of those), the chickens will develop antibodies against the immunogen that would be passed onto the egg — in a similar manner in which the cow provides immunity to the calf via colostrum.
These immunoglobulins (Ig) are mainly IgY (an analog to the mammalian IgG), IgM and IgA and are primarily found in the egg yolk, particularly IgY (Schade et al., 2001). They can be used as a liquid or solid (spray-dried) feed additive either as purified Ig or as whole egg (Shimizu et al., 1988).
Because the proposed mode of action is by passive immunity via oral administration, Ig needs to remain active in the rumen for a certain amount of time post-ingestion to be able to exert its activity.
The specific preparations of antibodies discussed in this article have been termed polyclonal antibody preparations (PAPs) because of the manner in which the antigen/antibody reaction takes place and because they are not in the form of purified IgY (DiLorenzo et al., 2006 and 2008).
While the exact mechanism by which PAPs work in the rumen is not fully elucidated, Schade et al. (2001) and Shimizu et al. (1988) have indicated that the structure of the avian IgY may provide certain advantages over more common mammalian IgG in terms of resistance to low pH and digestive proteases. This may partially explain why these PAPs may still be active in the rumen — at least for some time — without being "ruminally protected."
A series of studies conducted at the University of Minnesota revealed that when PAPs against either Streptococcus bovis or Fusobacterium necrophorum were fed to feedlot cattle over two consecutive years (531 steers total), an improvement in feed efficiency was observed (Figure). However, when both PAPs were fed in combination, the feed efficiency advantage over control steers receiving no PAP was lost.
Further investigating the effects seen in the feedlot performance study, the observation was made that when PAPs against either S. bovis or F. necrophorum were fed separately, ruminal counts of S. bovis (a Gram-positive bacterium linked to the onset of acidosis in grain-fed cattle) were decreased, but when both PAPs were added together, S. bovis counts were similar to the control.
While this observation alone may not solely explain the findings in feed efficiency, it is likely that the effect is mediated by a reduced acid load and, perhaps, the incidence of subclinical acidosis in steers receiving either PAP.
This was further confirmed by ruminal pH results in which an increase was observed when either preparation or the combination of both was fed (DiLorenzo et al., 2006 and 2008).
The effects of PAPs on ruminal pH were also evident in an acidosis challenge study conducted in Barcelona, Spain, by Blanch et al. (2009) in which heifers were rapidly transitioned from high-forage diets to high-grain diets.
Similarly, a study conducted using early-lactation dairy cows at the University of Minnesota showed that PAPs against selected bacteria were effective in modulating ruminal pH (DiLorenzo et al., 2007).
Studies conducted in Brazil using a PAP of multiple immunogens showed an increase in ruminal pH similar to that observed when giving monensin to cannulated cows fed high-concentrate diets (Marino et al., 2011).
Another study conducted in Brazil on feedlot cattle showed that the use of PAPs led to lesser rumenitis scores (indicative of potential acidosis-mitigating effects) when evaluated on washed rumens collected post-harvest (Pacheco et al., 2012). Despite the effects on rumenitis scores, Pacheco et al. observed no further effects on animal performance when feeding either monensin or PAP to yearling bulls receiving feedlot diets.
Targeting ruminal LPS
The lipopolysaccharide (LPS) component of Gram-negative bacteria is known to elicit an inflammatory response in beef and dairy cattle that affects feed intake and, thus, productivity. When ruminal pH decreases, more pH sensitive Gram-negative bacteria die and release LPS, which can enter blood circulation and create a systemic endotoxemia that elicits an acute-phase response.
Drastic decreases in ruminal pH typically occur in feedlot cattle consuming high-grain diets or in transition dairy cows that are suddenly exposed to increased levels of dietary starch.
Following a similar approach as the previously described study, a PAP was created against LPS to be used as a feed additive. In a study conducted at Texas Tech University, feeding a PAP against LPS to feedlot cattle during the last 84 days on feed led to greater dry matter intake (P = 0.02) compared to steers receiving a placebo made of inactivated PAP. Despite the differences in intake, no other effects on performance were observed.
Considering the effect that diet transition and increased ruminal LPS concentrations can have on feed intake and milk production during early lactation, studies are currently being conducted to test the efficacy of the same PAP in dairy cows in Florida.
The Bottom Line
Avian-derived PAPs as a feed additive for beef and dairy cattle may be a promising technology for the mitigation of metabolic disorders such as ruminal acidosis, which would increase animal productivity.
Preliminary data show that feeding avian antibodies against LPS may help reduce the productive cost of an acute-phase response in feedlot cattle and in transition dairy cows.
Further research is needed to fully understand the mode of action of these novel additives and their potential impact on animal performance.
Blanch, M., S. Calsamiglia, N. DiLorenzo, A. DiCostanzo, S. Muetzel and R.J. Wallace. 2009. Physiological changes in rumen fermentation during acidosis induction and its control using a multivalent polyclonal antibody preparation in heifers. J. Anim. Sci. 87:1722-1730.
DiLorenzo, N., C.R. Dahlen, F. Diez-Gonzalez, G.C. Lamb, J.E. Larson and A. DiCostanzo. 2008. Effects of feeding polyclonal antibody preparations on rumen fermentation patterns, performance and carcass characteristics of feedlot steers. J. Anim. Sci. 86:3023-3032.
DiLorenzo, N., C.R. Dahlen, J.E. Larson, R.K. Gill and A. DiCostanzo. 2007. Effects of feeding a polyclonal antibody preparation against selected rumen bacteria on rumen pH of lactating dairy cows. J. Anim. Sci. 85(suppl. 2):135(abstr.).
DiLorenzo, N., F. Diez-Gonzalez and A. DiCostanzo. 2006. Effects of feeding polyclonal antibody preparations on rumen bacterial populations and ruminal pH of steers fed high grain diets. J. Anim. Sci. 84:2178-2185.
Galyean, M.L., N. DiLorenzo and C.H. Ponce. 2010. Managing acidosis and related disorders in finishing cattle. In: Proceedings of the 31st Western Nutrition Conference, Sept. 21-23. Saskatoon, Sask. p. 1-15.
Marino, C.T., W.G. Otero, P.H.M. Rodrigues, A. DiCostanzo, D.D. Millen, R.L.D. Pacheco, N. DiLorenzo, C.L. Martins and M.B. Arrigoni. 2011. Effects of feeding polyclonal antibody preparations on ruminal fermentation patterns and digestibility of cows fed different energy sources. J. Anim. Sci. 89:3228-3235.
Pacheco, R.D.L., D.D. Millen, N. DiLorenzo, C.L. Martins, C.T. Marino, M.V. Fossa, S.L. Beier, A. DiCostanzo, P.H.M. Rodrigues and M.D.B. Arrigoni. 2012. Effects of feeding a multivalent polyclonal antibody preparation on feedlot performance, carcass characteristics, rumenitis and blood gas profile in Bos indicus biotype yearling bulls. J. Anim. Sci. 90:1898-1909.
Schade, R., I. Behn, M. Erhard, A. Hlinak and C. Staak (eds.). 2001. Chicken egg yolk antibodies, production and application. Chapter 1. Springer, Germany.
Shimizu, M., R.C. Fitzsimmons and S. Nakai. 1988. Anti-E. coli immunoglobulin Y isolated from egg yolk of immunized chickens as a potential food ingredient. J. Food Sci. 53:1360-1366.
*Nicolas DiLorenzo is a beef cattle specialist at the University of Florida. To expedite answers to questions concerning this column, please direct inquiries to Feedstuffs, Bottom Line of Nutrition, 7900 International Dr., Suite 650, Bloomington, Minn. 55425, or email [email protected]