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To determine the effect of harvest method and ammoniation on both in vivo and in vitro digestibility of corn residue, six corn residue treatments consisting of three different harvest methods either with or without anhydrous ammonia chemical treatment (5.5% of dry matter [DM]) were evaluated. The harvest methods included conventional rake-and-bale (CONV) and New Holland Cornrower with eight rows (8ROW) or two rows (2ROW) of corn stalks chopped into the windrow containing the tailings (leaf, husk, and upper stem) from eight rows of harvested corn (ammoniated bales of each harvest method resulted in treatments COVAM, 8RAM, and 2RAM). Nine crossbred wether lambs (49.2 ± 0.5 kg BW) were fed 64.2% corn residue, 29.8% wet corn gluten feed, 3.3% smooth-bromegrass hay, and 2.8% mineral mix (DM basis) in a 9 × 6 Latin rectangle metabolism study with a 3 × 2 factorial treatment to measure total tract disappearance. Six 21-d periods consisted of 14-d adaptation and 7-d total fecal collection, and lambs were fed ad libitum (110% of the previous day’s DM intake [DMI]) during days 1 to 12 and reduced to 95% of ad libitum intake for days 13 to 21. There was a harvest method by ammoniation interaction (P < 0.01) for ad libitum DMI (days 7 to 11). Ammoniation increased (P < 0.01) intake across all harvest methods, where 2RAM DMI was 4.1%, COVAM was 3.6%, and 8RAM was 3.1%, which were all different (P < 0.01) from each other, but all untreated residues were consumed at 2.6% of BW (P ≥ 0.92) regardless of harvest method. There were no interactions (P > 0.34) between harvest method and ammoniation for any total tract or in vitro digestibility estimate. Harvest method affected (P < 0.04) DM, neutral detergent fiber (NDF), and acid detergent fiber (ADF) digestibility, where 2ROW was greater than both CONV and 8ROW, which did not differ. The organic matter (OM) digestibility (P = 0.12) and digestible energy (DE; P = 0.30) followed the same numerical trend. Both in vitro DM digestibility (IVDMD) and in vitro OM digestibility (IVOMD) of the residue were affected (P < 0.01) by harvest method, with 2ROW being greater (P < 0.01) than both CONV and 8ROW. For IVDMD, 8ROW was not (P = 0.77) different from CONV, but 8ROW IVOMD was lower (P = 0.03) than CONV. Ammoniation improved (P < 0.01) DM, OM, NDF, and ADF digestibility of all harvest methods, resulting in a 26% increase (P < 0.01) in DE due to ammoniation. Similar digestibility improvements were observed in vitro with ammoniation improving IVDMD and IVOMD by 23% and 20%, respectively. Both selective harvest methods and ammoniation can improve the feeding value of baled corn residue.

To determine the effects of harvest method and ammoniation (3.7% of dry matter) on consumption and waste of baled corn residue, a 6 × 6 Latin square with a 3 × 2 factorial treatment structure was conducted. Six treatments consisted of either nonammoniated or ammoniated residue, harvested one of three ways: conventional rake and bale (CONV), New Holland Cornrower with two rows of stem chopped into the windrow with tailings (2ROW), or EZBale system (EZB) with a disengaged combine spreader and tailings dropped in a windrow. Open cows were grouped by body weight to produce a light block of two pens (448 kg ± 49.6) and a heavy block of four pens (649 kg ± 65.9). One bale was fed to each pen during each of six 7-d periods using round bale ring feeders with closed bottom panels. Residue falling around (waste) and remaining in (refusals) the feeder was collected. The daily nutrient intake was estimated as the difference between what was offered and what remained (waste plus refusals). Crude protein (CP) of residue offered did not differ (P = 0.58) among harvest methods. The digestible organic matter (DOM) content of residue offered in 2ROW and EZB bales did not differ (P = 0.86) and was greater (P < 0.01) than CONV. Ammoniation increased (P < 0.01) CP and DOM content of the residue offered. Total wasted and refused residue did not differ (P = 0.12) between 2ROW (29%) and EZB (37%), while CONV (42%) was greater (P = 0.02) than 2ROW but did not differ (P = 0.34) from EZB. Ammoniation reduced (P = 0.03) total waste and refusals from 41% to 32%. The nutrient content of both waste and refusals did not differ (P ≥ 0.34) among harvest methods and, with the exception of CP, was not affected (P ≥ 0.15) by ammoniation. The CP content of the waste was greater (P = 0.02) and refusals tended to be greater (P = 0.08) from ammoniated bales. The CP intake of 2ROW was greater (P ≤ 0.02) than both EZB and CONV, while EZB tended (P = 0.06) to be greater than CONV. The CP intake of all ammoniated residues was greater (P < 0.01) than the nonammoniated residue. The DOM intake of nonammoniated 2ROW and EZB did not differ (P = 0.61) but was greater than nonammoniated CONV (P < 0.01). Ammoniation increased (P < 0.01) DOM intake. Overall, ammoniation had much larger effects than harvest method, resulting in reduced waste and refusals and greater intake of DOM and CP. However, the combination of both ammoniation and selective harvest (2ROW or EZB) was needed to result in energy and protein intakes that would meet the needs of a mature cow in mid-gestation.

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