GEM and the UW Silage Breeding Project J.G. Coors D. Majee D.T. Eilert P.J. Flannery Department of Agronomy University of Wisconsin with acknowledgements to: J.G. Lauer UW Department of Agronomy R.D. Shaver UW Department of Dairy Science

Outline Silage quality – what is it? UW silage breeding system GEM contributions – silage germplasm GEM contributions – starch degradability Summary

Dry Matter Protein Carbohydrate Sugar and Starch Bugs Fiber Bugs Degradable protein Sugars & starch Cell wall Bound Unavailable starch Sugar and Starch Bugs Bound with Lignin Undegradable protein Fiber Bugs Digestible energy & protein Absorbed Metabolizable energy & protein Maintenance Growth Pregnancy Lactation

Milk2000

Processed Unprocessed Adapted from Schwab and Shaver, unpublished. Based on data of Bal et al., 2000; Dhiman et al., 2000; Rojas-Bourrillon et al., 1987

GEM Contributions – Silage Germplasm Phase I Silage evaluation of elite GEM topcrosses (~15-25) that were identified in prior years by other GEM cooperators as having high grain yield and suitable maturity for Wisconsin (<120RM). Phase 2 For those topcrosses with high forage yield and good nutritional quality in Phase 1 trials, the respective GEM breeding population is included in the UW inbred development nursery for further inbreeding and selection Phase 3 Inbred development – testcrosses at S2 to S6 generations using two to four inbred testers

2004 UW GEM Program Phase I Phase 2 Phase 3 17 breeding populations or early generation GEM inbred families crossed to LH185, LH198, LH200, LH244, or LH287 were evaluated for silage potential (GEMNEW). Phase 2 Gem inbreeding nursery included ~400 inbred families from 10 breeding populations. Most inbred families (~170) were derived from CUBA164 background. Phase 3 160 advanced generation inbreds from six populations were crossed to two testers each for evaluation in 2005. Evaluated ~50 S3+ families topcrosses to two testers (GEM198, GEM244). 27 promising S4+ families evaluated in topcrossed to two to four testers each (GEMADV).

Forage yield for GEMNEW trial in 2004 Entries marked with “*” will be analyzed for nutritional quality

2004 UW GEM Program Phase I Phase 2 Phase 3 17 breeding populations or early generation GEM inbred families crossed to LH185, LH198, LH200, LH244, or LH287 were evaluated for silage potential (GEMNEW). Phase 2 Gem inbreeding nursery included ~400 inbred families from 10 breeding populations. Most inbred families (~170) were derived from CUBA164 background. Phase 3 160 advanced generation inbreds from six populations were crossed to two testers each for evaluation in 2005. Evaluated ~50 S3+ families topcrosses to two testers (GEM198, GEM244). 27 promising S4+ families evaluated in topcrossed to two to four testers each (GEMADV).

2004 UW GEM Program Phase I Phase 2 Phase 3 17 breeding populations or early generation GEM inbred families crossed to LH185, LH198, LH200, LH244, or LH287 were evaluated for silage potential (GEMNEW). Phase 2 Gem inbreeding nursery included ~400 inbred families from 10 breeding populations. Most inbred families (~170) were derived from CUBA164 background. Phase 3 160 advanced generation inbreds from six populations were crossed to two testers each for evaluation in 2005. Evaluated ~50 S3+ families topcrosses to two testers (GEM198, GEM244). 27 promising S4+ families evaluated in topcrosses to two or four testers each (GEMADV).

Forage yield for GEM198 and GEM244 trials in 2004

Forage yield for GEMADV trial in 2004

WQS/GQS S5 families S6 lines S1 families (~500) Season 1 (winter) Season 2 (summer) Evaluate &  Recombine S3 families (~150) Testcross (1 tester) S2 testcrosses (~150) Season 3 (winter) Evaluate & select S2 families (20 selects) Season 4 (summer) Season 5 (winter) S4 families (~20-40 selects) S4 testcrosses (~75-100) Season 6 (summer) Season 7 (winter) Increase S4 selected families (2-3 testers) Inbred release Sample hybrids for distribution WQS/GQS 

Components of GEM Quality Synthetic (GQS) 2003 trial, LH279 topcrosses

GEM Contributions – Starch Degradability Starch and the kernel contribute about 55% and 75% of the energy value of corn silage, respectively (Shaver and Schwab, 2001). Corn grain vitreousness was found to increase with advancing maturity and ruminal starch degradation decreases linearly as vitreousness increase (Correa et al., 2001). The proportion of vitreous and floury endosperm that surrounds starch granules was found to determine endosperm texture (Michalet-Doreau and Doreau, 1999). Kernel composition, structure and density is known to affect hardness characteristics (Martin et al, 1987). Whilst kernel density is in turn affected by the relative amounts of the major nutrient components (e.g. starch and its proportion of amylose to amylopectin; and protein) and their packing. Hence, there is need to evaluate kernel endosperm characteristics that can be easily used to screen corn germplasm in large breeding programs for livestock feeding.

Rumen Degradability of Starch

Starch Degradability Oh43 o2 CHO5015:N12-387-1-B Starch and the kernel contribute about 55% and 75% of the energy value of corn silage, respectively (Shaver and Schwab, 2001). Corn grain vitreousness was found to increase with advancing maturity and ruminal starch degradation decreases linearly as vitreousness increase (Correa et al., 2001). The proportion of vitreous and floury endosperm that surrounds starch granules was found to determine endosperm texture (Michalet-Doreau and Doreau, 1999). Kernel composition, structure and density is known to affect hardness characteristics (Martin et al, 1987). Whilst kernel density is in turn affected by the relative amounts of the major nutrient components (e.g. starch and its proportion of amylose to amylopectin; and protein) and their packing. Hence, there is need to evaluate kernel endosperm characteristics that can be easily used to screen corn germplasm in large breeding programs for livestock feeding. CHO5015:N12-387-1-B Oh43 o2

[Correa et al., 2002]

Starch Degradability Studies Objectives Determine whether there is genetic variation for starch degradability Determine the extent to which kernel vitreousness is related to starch degradability

Starch Study Entries: 32 inbred lines and 1 population (2002) 19 hybrids (2003) Harvest dates: ½ milkline (ML, ~35% DM) Black layer (~15 d post ½ ML) Experiment design (field): RCB with 3 replicates Madison - 2002, 2003 1 self-pollinated row – 3.04 x 0.76 m 10 plants per row

Procedure – Two-Stage Starch Digestion (Pioneer Hi-Bred International, Inc.) STAGE 1 - in-situ ruminal incubation Two steers with ruminal cannula – 2 wk adaptation to 70% (DMB) corn silage diet In-situ procedure: Corn kernels ground with Wiley Mill (6mm screen) 1.5g ground material placed in 5 x 5 cm dacron bag Eight replicate bags incubated for each sample Placed in rumen for 0 and 14 h, Removed, rinsed and dried at 62oC for 24 h STAGE 2 - post-ruminal in-vitro incubation 14-h ruminal residue subjected to 8 h incubation intestinal enzymatic cocktail (pepsin + pancreatic enzymes) Final Action Eight replicates for DM disappearance Eight replicated bags composited for a single starch analysis

½ milk-line stage

Black layer stage

Black layer stage W64A X Oh43 o2 W64A X Oh43 fl2 W64A X Oh43 su2

Black layer stage – hybrids

Summary GEM has contributed greatly to the UW silage breeding program by providing: 1) Superior and unique germplasm 2) Better understanding of nutritional properties of silage http://silagebreeding.agronomy.wisc.edu