Effect of harvest method and ammoniation on apparent digestibility and intake of baled corn residue in lambs

The objective of this study was to assess the effect of three different harvest methods and ammonia treatment on the in vivo digestibility of baled corn residue. Nine wether lambs (49.2 ± 0.5 kg BW) were used in a 9 x 6 Latin Square design with a 3 x 2 factorial treatment structure; 3 harvest methods [conventional rake and bale (COV), New Holland Cornrower with 8 rows (high-stem; HS) or 2 rows (low-stem; LS) of corn stalks chopped into the windrow containing leaf, husk and upper stem] and ammoniation at 3% of DM of the resulting baled residue. Diets consisted of 64.2% corn residue, 29.8% Sweet Bran, 3.3% smooth-bromegrass hay, and 2.8% mineral mix (DM basis). Periods were 21 d (14 d adaptation and 7 d total fecal collection). Lambs were fed ad-libitum (110% of the previous day's DMI) during d 1 to 12 and reduced to 95% of ad-libitum intake for d 13 to 21. Treatment diets were fed over 6 periods, with the non-residue proportion of the diet (Sweet Bran, smooth-bromegrass hay, and mineral mix) fed alone in an additional period to determine the digestibility of the residue by difference. There was a harvest method by ammoniation interaction for ad-libitum DMI (d 7 to 12). Intake of non-ammoniated residue diets did not differ (P ≥ 0.92) among harvest methods, however, ammoniation increased (P ≤ 0.05) intake with LS having the greatest increase, COV being intermediate and HS having the least increase. There was no harvest method by ammoniation interaction for DM or OM digestibility. Digestibility of DM (DMD) differed between harvest methods, with LS being greater than COV (P = 0.01) and tending (P = 0.10) to be greater than HS. Ammoniation increased DMD of the residues by 25% (10.2% units). Digestibility of OM (OMD) tended to be affected by harvest method with LS tending (P = 0.06) to be greater than COV. Ammoniation improved OMD of all harvest methods, resulting in a 22% (10.1% units) increase. Utilizing alternative harvesting technologies and ammoniation can improve the feeding value of baled corn residue.