Selection for Silage Quality in the Wisconsin Quality Synthetic and Related Maize Populations

to increasing total energy content through (i) increasing the contribution of grain and (ii) increasing the digestMaize (Zea mays L.) silage is a high-quality forage for ruminants, ibility of the stover. Much of the variation in forage dibut there have been few significant breeding efforts specifically dedicated to improving maize forage yield or quality by breeders in the gestibility can be accounted for by differences in rates USA. The objective of this study was to evaluate the forage yield of fiber digestion and passage through the gut (Waldo and quality of the Wisconsin Quality Synthetic (WQS) and related et al., 1972). Ruminal function and animal health are populations developed by the University of Wisconsin Maize Breeding optimal in forage-based diets (Jung and Allen, 1995), Program for agronomic and nutritional attributes. Three cycles of and performance depends on intake of digestible and divergent S1 recurrent selection have been completed for stover fiber, metabolizable nutrients (Mertens, 1994). The importance silica, and lignin concentration for populations WFISIHI (Wisconsinof digestibility of the fiber was apparent in a study confiber-silica-high) and WFISILO (Wisconsin-fiber-silica-low). The third ducted by Muller et al. (1972) who fed lambs both cycle (C3) of WFISILO was crossed to two high-quality inbred lines, brown-midrib and normal maize forages that were enMo17 and H99, to create WQS C0, which then underwent two cycles of siled without the ears. The NDF concentrations of the S2–topcross selection for improved forage yield and quality. All cycles of selection for WFISIHI, WFISILO, and WQS were evaluated for hybrids were all equal, but NDFD was 20% greater in forage yield and quality at two field locations in Wisconsin in 2000 the brown-midrib forage. This resulted in 29% more and 2001. Results for WFISIHI and WFISILO demonstrated that S1 DM intake by lambs fed the brown-midrib hybrid comselection for stover composition altered both stover and whole-plant pared with the normal hybrid. Differences in the browncomposition in the anticipated directions. Selection for whole-plant midrib hybrid not only affected digestibility but also yield and composition of S2–topcrosses was also effective for WQS, esintake resulting in a substantially greater intake of dipecially when using selection indices incorporating whole-plant yield, gestible energy. In more recent studies, Oba and Allen neutral detergent fiber (NDF), neutral detergent fiber digestibility (1999, 2000a, 2000b) found that brown-midrib maize (NDFD), crude protein (CP), and starch. WQS C2 whole-plant and silage that includes the brown-midrib3 (bm3) gene had stover in vitro true digestibility (IVTD), whole-plant and stover acid high dry matter intake and milk yield. The effects of detergent lignin, and milk yield per megagram dry matter (DM) were similar to the brown-midrib check hybrid, F657. WQS C2 wholethe bm3 gene are most evident on productivity in cows plant and stover NDFD were lower than F657 but higher than other fed high NDF diets in conjunction with the bm3 maize commercial check hybrids. In addition, WQS population testcrosses silage (Oba and Allen, 2000a). Further, Oba and Allen improved over cycles of selection for whole-plant yield and most (1999, 2000b) stated that, although enhanced in vitro quality attributes. Our results indicate that it is feasible to develop NDFD was associated with increased milk production, silage maize germplasm with both high whole-plant yield and excellent NDFD appeared to more directly affect rate of passage nutritional quality. and dry matter intake rather than overall energy concentration. Tyrrell and Moe (1975) stated that as intake of less digestible forage increases, the efficiency of digestion T has been little breeding effort to improve maize may decrease. Because of the increased effort to improve forage yield or quality in the USA (Lauer et al., 2001). the genetic potential for growth and lactation of rumiThe existence of genetic variation for forage nutritive nants, there is a need for high-quality maize to aid in quality in maize has been shown previously (Barrière increasing the gains for growth and lactation of rumiand Argillier, 1998; Argillier et al., 1995, 2000). Barrière nants (Jung and Allen, 1995). and Argillier (1998) stated that the specific breeding of The University of Wisconsin Maize Breeding Program maize for forage quality started 15 to 20 yr ago, albeit initiated an S1 family recurrent selection project in 1985 with germplasm previously selected for grain yield. Barto develop experimental germplasm with altered fiber rière and Argillier (1998) further suggested that to procomposition. Buendgen et al. (1990) first described the duce a silage maize that possesses high yield, high qualWFISIHI and WFISILO maize populations that were deity, and high lodging resistance, the breeders must utilize veloped to be high and low, respectively, for NDF, lignin, digestibility analyses in their breeding program. Coors and silica concentrations of the leaf sheath. These popuand Lauer (2001) suggested there are two approaches lations were used initially to evaluate the relationship of fiber composition with European corn borer [Ostinia T. J. Frey, Dep. of Plant and Soil Sciences, Univ. of Delaware, Newark, DE 19716; J.G. Coors, J.G. Lauer, D.T. Eilert, and P.J. Flannery, Abbreviations: ADF, acid detergent fiber; ADL, acid detergent lignin; Dep. of Agronomy, Univ. of Wisconsin, Madison, WI 53706; R.D. bm3, brown-midrib3; CP, crude protein; DM, dry matter; ECB, EuroShaver, Dep. of Dairy Science, Univ. of Wisconsin, Madison, WI 53706. pean corn borer; IVTD, in vitro true digestibility; L, lignin; NDF, Received 2 July 2003. *Corresponding author (travisfrey@psualum. neutral detergent fiber; NDFD, neutral detergent fiber digestibility; com). NIRS, near-infrared reflectance spectroscopy; SEC, standard error of calibration; SECV, standard error of cross-validation; WQS, WisconPublished in Crop Sci. 44:1200–1208 (2004).  Crop Science Society of America sin Quality Synthetic; WFISIHI, Wisconsin-fiber-silica-high; WFISILO, Wisconsin-fiber-silica-low. 677 S. Segoe Rd., Madison, WI 53711 USA