Methods to evaluate the nutritive value of whole-plant corn silage

Transcription

1 Methods to evaluate the nutritive value of whole-plant corn silage Luiz F. Ferraretto, Ph.D., PAS Department of Animal Sciences University of Florida

2 Objective Introduce indicators of corn silage nutritive value Highlight the use and application of these indices Discuss some practical strategies to enhance these indices

3 Whole-Plant Corn Silage Grain ~40-45% of WPDM Avg. 30% starch in WPDM Variable grain:stover Stover= ~55-60% of WPDM Avg. 42% NDF Variable stover:grain 80 to 98% StarchD Kernel particle size Duration of silage fermentation Kernel maturity End osperm properties Additives 40 to 70% IVNDFD Lignin/NDF Hybrid Type Maturity Additives Variable pendf as per chop length

4 US Corn Silage Quality Summary Parameter Indicates Better Quality n Normal Range NDF (% DM) 384, Lignin (% DM) 344, undf 240 (% DM) 81, NDFD 30 (% NDF) 170, TTNDFD (% NDF) 27, Starch (% DM) 347, Milk per ton 136, Summary of combined multi-year, multi-lab (CVAS, DairyOne, RRL, DLL) data, except TTNDFD only from RRL Slide courtesy of Dr. Randy Shaver, UW-Madison

5 Corn Silage Quality Indicators Indicator NDF (% DM) Lignin (% DM) undf 240 (% DM) NDFD 30 (% NDF) TTNDFD (% NDF) Practical Implication Intake limitation through rumen fill Impact milk yield and the establishment of high-forage diets Methods vary across laboratories and may include calculation of pools and rates of digestion.

6 Forage NDF digestibility and cow performance For every 1 percentageunit increase in NDF digestibility kg/d DMI kg/d 4%FCM (Oba and Allen, 1999) >40% corn silage in diet kg/d DMI kg/d 3.5%FCM (Jung et al., 2010)

7 Corn Silage Quality Indicators Indicator Starch (% DM) StarchD (% starch) Prolamin (% DM) Practical Implication Alter energy density Impact milk yield or feed efficiency Methods vary across laboratories and may include calculation of rates of digestion.

8 lb of milk per ton of silage DM Corn Silage Quality Indicators Indicator Milk per ton ,0 8,0 9,0 10,0 Yield of DM, Tons per acre Used as an index for ranking corn hybrids commonly used by University Hybrid Performance Trials

9 Ruminal in vitro / in situ digestibility

10 Ruminal in vitro / in situ NDF digestibility Standard industry procedures to determine NDF digestibility in feedstuffs Uses dried and 1-2 mm ground samples Incubates samples for 30 h (some labs perform other timepoints) Rates and extents of NDF digestibility are maximized

11 Ruminal in vitro / in situ starch digestibility Standard industry procedures to determine starch digestibility in feedstuffs Uses dried and 4-6 mm ground samples Incubates samples for 7 h (some labs perform 3 h) Does it account for kernel processing effects?

12 Ruminal in vitro starch digestibility SHRD KPCS CSPS, % starch < 4.75 mm sieve h ivsd, % of starch h issd, % of starch h issd, % of starch TTSD, % of starch intake Ruminal in situ analysis performed on undried and unground samples Adapted from Ferraretto and Shaver, 2012

13 Ferreira and Mertens, 2005 Corn Silage Processing Score

14 Ro-Tap Shaker Corn Silage Processing Score 9 sieves (0.6 thru 19 mm) and pan Analyze for starch > 4.75 mm sieves % of starch passing 4.75 mm sieve >70% 70% to 50% < 50% KPS Excellent Adequate Poor

15 Industry Makes Advances in Corn Silage Processing Crop Year Number Average Percent Optimum Percent Poor Adapted from slide provided by Ralph Ward of CVAS

16 Braman and Kurtz, 2015 Corn silage processing score and fecal starch

17 Kernel particles 2P 4P 8P 16P 32P 64P P = pieces Dias Junior et al., 2016

18 Kernel particles and CSPS Item WH 2P 4P 8P 16P 32P 64P Sieves, mm Pan GMPS, µm Dias Junior et al., 2016

19 (% of Nutrient) Ruminal in situ DM digestibility of unfermented kernels 80 WH 2P 4P 8P 16P 32P 64P Dias Junior et al., 2016 Time points (h)

20 % Digested Starch Digestion In Vitro by Particle Size Over Time 2.36 mm 1.7 mm 1.18 mm 0.85 mm 0.6 mm mm 0.3 mm <.3 mm Hours Adapted from slide provided by Ralph Ward of CVAS

21 80 corn silage samples CSPS vs. kernel GMPS Samples were split in half First half CSPS (Ferreira and Mertens, 2005) Second half- kernel and stover fractions were separated by hydrodynamic separation procedure (Savoie et al., 2004). Dias Junior et al., 2016

22 Hydrodynamic Separation

23 Is CSPS related to GMPS of kernels? Parameter Estimates Model Statistics Predicted Intercept SE 1 Slope SE P-value R 2 RMSE 2 GMPS, µm Surface area, cm 2 /g Dias Junior et al., 2016

24 How can we improve NDF and starch digestibility of the corn silage you are planning to feed me?

25 Maturity at harvest Should we keep plants longer in the field to harvest greater yields of DM and starch?

26 Kernel Vitreousness (%) Kernel vitreousness 80 Johnson et al. (2002) - exp Johnson et al. (2002) - exp. 2a Johnson et al. (2002) - exp. 2b Philippeau and Michalet-Doreau (1997) - dent Philippeau and Michalet-Doreau (1997) - flint Correa et al. (2002) 30 Ferraretto et al. (2015) - bm Kernel DM concentration (% of as fed) Ferraretto et al. (2015) - leafy-floury Ferraretto et al. (2015) - dual-purpose Ferraretto et al., 2018, JDS Accepted

27 UF Harvest Maturity Trial 18 hybrids with relative maturity of 115 to 120 days Planted during the summer 4 targeted harvest maturities:30, 35, 40 and 45%DM Arriola et al. (2015)

28 UF Harvest Maturity Trial Item 30% 35% 40% 45% NDF, % of DM 45.6 a 42.1 b 39.7 c 42.6 b CP, % of DM Sugars, % of DM Starch, % of DM ivndfd, % of NDF Yield of DM, t/ha 21.9 b 21.9 b 23.1 b 25.5 a Milk per t, kg/t 1661 a 1675 a 1586 b 1477 c Milk per area, kg/ha Arriola et al. (2015)

29 Take home message 1 Maturity plays a major role on corn silage quality and digestibility Modern hybrids are susceptible to these effects DM content varies within and among fields, target for 35% DM to avoid exceeding 40% DM

30 Corn Silage Fermentation Increases Starch Digestibility!

31 In Vitro Starch Digestibility (%) Response across multiple trials Der Bedrosian Windle Young Ferraretto-1 Ferraretto-2 Ferraretto-3 Ferraretto Fermentation Time (days) Figure 1. Effect of days of ensiling on ruminal in vitro starch digestibility. Data from Der Bedrosian et al., 2012; Windle et al., 2014; Young et al., 2012; Ferraretto-1, Ferraretto et al., 2015a; Ferraretto-2, Ferraretto et al., 2015b; Ferraretto-3,4, Ferraretto Slide courtesy of Dr. Randy Shaver, UW-Madison

32 Take home message 2 Research supports the use of inventory planning so a newly harvest crop would be fed only after days in storage Ensiling time does not attenuate differences in starch digestibility caused by hybrids or maturity It requires proper management during filling, packing and covering

33 Normal vs. high cutting height Average of 7 studies Cutting height, cm NDF, % ivndfd, % of NDF Starch, % Yield, t of DM/ha Milk, kg/t Milk, kg/ha Ferraretto et al., 2018, JDS Accepted

34 Take home message 3 Cutting height improved quality but at the expense of reduced yield Cutting height may be a feasible option to improve forage quality when acreage is not a limiting factor

35 Questions???