Currently there is much interest in the dairy industry about brown midrib corn. Brown midrib corn was first discovered in dent corn at St. Paul, MN in 1924. It was thought to occur as a natural mutation of regular dent corn. Since its initial discovery a total of four brown midrib mutants have been identified:

bm1 (Jorgenson, 1931)
bm2 (Burnham and Brink, 1932)
bm3 (Emerson et al., 1935)
bm4 (Burnham, 1947)

Brown midrib corn plants exhibit a reddish-brown pigmentation of the leaf midrib at V4 to V6. The pigmentation is also seen in rind and pith. Coloring eventually disappears on leaves, but remains in the stalk. The brown midrib phenomenon is also found in sorghum, sudangrass, and pearl millet.

About 40 years after the initial discovery, bmr mutations were found to have a drastic effect on lignin (Lechtenberg et al., 1972) and that digestibility of corn silage was improved in ruminants. Below are the initial studies involved with various ruminants:

sheep (Muller et al., 1972)
goats (Gallais et al., 1980)
heifer cattle (Colenbrander et al., 1972, 1973, 1975)
beef cattle (Keith, 1981)
dairy cows (Frenchick et al., 1976)

A total of 18 agronomic and dairy cattle feeding trials comparing brown midrib corn and regular dent corn were summarized (Fig. 1). Usually either yield or quality results were published, rarely both. In these studies, brown midrib corn produced on average 6% less yield than regular dent corn. Fiber as measured by ADF and NDF was 3 and 2% lower for brown midrib than regular dent corn. Using MILK91 (Undersander et al., 1993), milk per ton and milk per acre were calculated and brown midrib corn increased milk per ton 4%, but decreased milk per acre 2%.

In the U.S. results of feeding bmr corn are either inconclusive or trended slightly in favor. A significant increase in milk production was observed only once (Keith et al., 1979). Increased body weight was noted every time bmr was fed. Energy intake was not limiting in these studies and it seems that extra nutrients digested in bmr corn are partitioned into meat or fat body tissues rather than milk. Feeding results from England (Weller and Phipps, 1986) and France (Hoden et al., 1985) indicate increased milk production.

Some things to think about as you consider using brown midrib corn as a corn silage in your dairy operation. Advantages include:

Increased silage intake
Increased digestibility of stover

Disadvantages include:

Lower yields: Whole plant silage and Grain
Susceptibility to lodging
Poor early season vigor
Delayed flowering
Slower early season growth rates

Literature Cited

Barriere, Y. and O. Argillier. 1993. Brown-midrib genes of maize: a review. Agronomie 13:865-876.

Barriere, Y., O. Argillier, B. Chabbert. M.T. Tollier, and B. Monties. 1994. Breeding silage maize with brown-midrib genes. Feeding values and biochemical characteristics. Agronomie 14:15-25.

Block, E., L.D. Muller, and L.H. Kilmer. 1982. Brown midrib-3 versus normal corn plants (Zea mays L.) harvested as whole plant or stover and frozen fresh or preserved as silage for sheep. Can. J. Animal Sci. 62:487-498.

Burnham, C.R. 1947. Maize Genet Coop News 21:36.

Burnham, C.R., and R.A. Brink. 1932. Linkage relations of a second brown midrib gene (bm2) in maize. J. Am. Soc. Agron. 24:960-963.

Cherney, J.H., D.J.R. Cherney, D.E. Akin, and J.D. Axtell. 1991. Potential of brown-midrib, low-lignin mutants for improving forage quality. Advances in Agronomy 46:157-198.

Colenbrander, V.L., L.F. Lechtenberg, L.F. Bauman, L.D. Muller, and C.L. Rhykerd. 1972. Nutritive value of brown midrib corn silage. J. Animal Sci. 35:1113.

Colenbrander, V.L., L.F. Lechtenberg, and L.F. Bauman. 1973. Digestibility and feeding value of brown midrib corn stover silage. J. Animal Sci. 37:294-295.

Colenbrander, V.L., L.F. Lechtenberg, and L.F. Bauman. 1975. Feeding value of low lignin corn silage. J. Animal Sci. 41:332-333.

Emerson, R.A. et al. 1935. Cornell Univ. Agric. Exp. Stn. Memoir 180.

Frenchick, G.E., D.G. Johnson, J.M. Murphy, and D.E. Otterby. 1976. Brown midrib corn silage in dairy cattle rations. J. Dairy Sci. 59:2126-2129.

Gallais, A., L. Huguet, H. Berthet, G. Bertin, B. Broqua, A. Mourguet, and R. Traineau. 1980. Preliminary evaluation of brown midrib maize hybrids for their feeding and agronomic value in France. In W.G. Pollmer and R.H. Phipps (eds.) Improvement of quality traits of maize for grain and silage use pp. 319-339.

Gentinetta, E., M. Bertolini, I. Rossi, C. Lorenzoni, and M. Motto. 1990. Effect of brown midrib-3 mutant on forage quality and yield in maize. J. Genet. and Breed. 44:21-26.

Hoden, A., Y. Barriere, A. Gallais, L. Huguet, M. Journet, and A. Mourguet. 1985. Le mais brown midrib plante entiere. 3. Utilisation sous forme d'ensilage par les vaches laitieres. Bull. Tech. CRZV Theix INRA 60:43-58.

Jorgenson, L.R. 1931. Brown midrib in maize and its lignage relations. J. Am. Soc. Agron. 23:549-557.

Keith, E.A., V.F. Colenbrander, V.L. Lechtenberg, and L.F. Bauman. 1979. Nutritional value of brown midrib corn silage for lactating dairy cows. J. Dairy Sci. 62:788-7

Keith, E.A., V.F. Colenbrander, T.W. Perry, and L.F. Bauman. 1981. Performance of feedlot cattle fed brown midrib-three or normal corn silage with various levels of additional corn grain. J. Animal Sci. 52:8-13.

Lechtenberg, V.L., L.D. Muller, L.F. Bauman, C.L. Rhykerd, and R.F. Barnes. 1972. Laboratory and in vitro evaluation of inbred and F2 populations of brown midrib mutants of Zea mays L. Agron. J. 64:657-660.

Muller, L.D., V.L. Lechtenberg, L.F. Bauman, R.F. Barnes, and C.L. Rhykerd. 1972. In vivo evaluation of a brown midrib mutant of Zea mays. J. Animal Sci. 35:883-889.

Rook, J.A., L.D. Muller, and D.B. Shank. 1977. Intake and digestibility of brown-midrib corn silage by lactating dairy cows. J. Dairy Sci. 60:1894-1904.

Undersander, D.J., W.T. Howard, R.D. Shaver. 1993. Milk per acre spreadsheet for combining yield and quality into a single term J. Prod. Agric. 6:231-235.

Weller, R.F., and R.H. Phipps. 1986. The feeding value of normal and brown midrib-3 maize silage. J. Agric. Sci., Camb. 106:31-35.

Weller, R.F., R.H. Phipps, and A. Cooper. 1985. The effect of the brown midrib-3 gene on the maturity and yield of forage maize. Grass and Forage Sci. 40:335-339.

Weller, R.F., R.H. Phipps, and E.S. Griffith. 1984. The nutritive value of normal and brown midrib-3 maize. J. Agric. Sci., Camb. 103:223-227.