Ammoniation of Flax, Lentil, and Wheat Straws and Wheat Chaff

Abstract

Ammonia treatment of flax straw (Linum usitassimum ) (FLAX), wheat straw (Triticwn aestivum ) (WHST) and wheat chaff (WHCH) was evaluated in a two year study by examining the effect of 3.5% (w/w) anhydrous ammonia treatment on chemical composition, in vitro and in vivo digestibility and voluntary intake. Ammoniated flax straw (NFLAX), wheat chaff, ammoniated wheat chaff (NWHCH) and ammoniated wheat straw (NWHST), supplemented with barley, were compared to bromegrass (Bromus inermis ) /alfalfa hay (Medicago sativa )(HAY) as maintenance rations for cows over two years. Lentil straw (Lens culinaris ) (LENTIL) and ammoniated lentil straw (NLENTll...) treatments were added in Year 2 of the study. All levels significant at P<0.05.���� Crude protein (CP) contents of FLAX, WHCR, WHST, LENTIL and HAY (Year1, Year2) were 2.S, 4.0; 5.7, 6.4; 3.1, 5.7; -, 7.5 and 14.5, 17.4% respectively while acid detergent lignin (ADL) contents were 10.6, -12.S; 6.6, 6.3; 6.S, 6.8; -,9.4 and . 4.2, 5.3% respectively. In vitro organic matter digestibility' (IVOMD) was 36.4, 39.2; 39.2, 44.7; 43.3, 33.5; -, 50.1 and 68.8, 71.5% respectively. Ammoniation improved CP content of FLAX, WIlCR and WIlST 96.4, 112.3 and 109.7% in Year1 and 125.0, 114.1 and SO.7% in Year2 respectively. CP content of LENTn.. improved 12S%.Respective values for IVOMD improvement were 30.5, 2S.S and 3.5 and 16.1, -7.2 and 26.6% bfor FLAX, WHCR and WHST respectively. IVOMD of LENTll.. improved 6.4%. In Year1 of the winter maintenance trials cows received from 2.3 to 5.6 kg d-l barley and from 3.0 to 10.1 kg d-1 crop residue. Intake of HAY fed alone averaged 10.2 kg d-l over 112d. Average daily gains (ADO) of cows (mature cows (4 years and older), younger cows (3 years old» fed HAY (LIS, 1.16 kg d-1) were greater than cows fed NFLAX (0.91,0.97 kg d-1) which were greater than cows fed NWHCH (0.71, 0.76 kg dI) and cows fed WHCR (0.55, 0.68) and NWHST (0.56, 0.70). ADO of cows fed NWHCH were significantly higher than those of cows fed WHCH despite lower levels of barley. Change in backfat (BF) of younger cows was greatest for HAY and NFLAX (4.Omm) followed by NWHST and NWHCH (2.Omm) and then by WHCH (O.Omm). Barley intake in Year2 ranged from 1.7 to 2.4 kg d-1. Intake of crop residues ranged from 4.5 to 8.S kg d-I while intake of HAY averaged 8.5 kg d-I over 78d. In mature cows, ADO were greatest for LENTll.. (0.63 kg d-1) followed by NLENTll.. (0.40 kg d-1) and NWHCH (0.23 kg d-1) and then by NWHST (0.19 kg d-1), NFLAX (0.14 kg d-1), HAY (0.12 kg d-1) and WHCH (0.06 kg d-1). ADO of younger cows were greatest for HAY (0.71 kg d-1), NLENTIL (0.69 kg d-1), LENTll.. (0.61 kg d-1) and NWHST (0.57 kg d-1) followed by NWHCH (0.45 kg d-1) and then WHCH (0.42 kg d-1) and NFLAX (0.35 kg d-1). Change in BF was not significant for mature or younger cows and averaged less than ! mm. Level of barley was constant for type of crop residue. Therefore, differences in ADG between untreated and ammoniated WHCH and LENTll...are due to differences in energy availability. In vivo organic matter digestibility (IVVOMD) was determined indirectly. In Yearl , flax and wheat straw rations were supplemented with 2 kg sweet clover (Melilotus officinalis ) and 1 kg dairy concentrate while wheat chaff rations received dairy concentrate alone and hay was fed alone. IVVOMD of FLAX, WHCH, WHST and HAY was 33.9, 55.3, 42.6 and 62.0% respectively. Ammoniation improved IVVOMD of FLAX and WHCH significantly by 72% and 14.8% respectively. In Year2 all rations except HAY were supplemented with 1 kg alfalfa pellets. IVVOMD of FLAX, WHCH, WHST, LENTll.. and HAY were 64.2, 44.5, 37.8, 40.0 and 61.7% respectively. Ammoniation improved IVVOMD of WHCH and WHST significantly by 32.3% and 27.5% respectively. IVVOMD ofNLENTIL was nonsignificantly improved by 16.0%. Improved IVOMD and IVVOMD resulting from ammoniation was partially due to improved fiber digestibility. Fiber digestibility (Neutral detergent fiber digestibility (NOFD), acid detergent fiber digestibility (ADFD» of FLAX, WHCH and WHST in Year l were improved 379, 343; 22.2, 20.7; and 47.9, 75.9%. In Year2 fiber digestibility (NDFD, ADFD) of FLAX, WHCH, WHST and LENTIL improved 8.8, 35.0; 44.5, 70.3; 24.4,36.7 and 8.0, 6.2% respectively. Changes in NDFD and ADFD were significant for FLAX in Year! and WHCH in Year2 and for ADFD of WHST in Yearl. NDFD and ADFD of HAY were 50.2% and 43.2% in Year! and 57.3% and 45.2% in Year2. Intake of FLAX and WHCH improved significantly in Year1. Intake of WHST improved significantly in Year2. Changes in chemical composition, IVOMD, IVVOMD and OM! of flax, wheat and lentil straw and wheat chaff indicate that ammonia can improve the nutritive value of these crop residues but that response is variable and dependent on initial straw quality, OM content and ambient temperature at time of curing. ADO was excessive in Year! of the winter maintenance trials. However, when barley supplementation was limited to 1.7 to 2.4 kg d-1 all crop residues examined produced adequate ADO in non-lactating, gestating beef cows entering the wintering period in good condition.