Treatment of whole-crop cereals with alkali. 4. Voluntary intake and growth in steers given wheat ensiled with sodium hydroxide, urea or ammonia

Urea-assisted ensiling process of wilted maize stover for profitable biomethane production

Low contents of water-soluble carbohydrates and/or low indigenous microbial activity in wilted maize stover (WMS) usually hinder the establishment of the ensiling process, thereby resulting in a low biogas production because of high loss of dry matter (DM). To enhance the biological activity and substrate biodegradability, this study applied the synergistic regulation of sucrose (carbon source) and increasing levels of urea (nitrogen source) during the ensiling process of WMS. Compared with the application of only sucrose, a higher organic acid content (lactic acid (85 g/kg-DM) and acetic acid (14 g/kg-DM)) and higher degradation ratios for lignocellulose (hemicellulose (28%), cellulose (22%), and lignin (17%)) were observed with urea applications of 1.7% (DM) and 3.9% (DM), respectively. This was caused by the enhanced activities of the hetero-fermenter (Weissella) and cellulolytic bacteria (Cellulosimicrobium). A simultaneous addition of urea and sucrose during the ensiling of WMS increased the specific methane yield by 11.2%-21.1% in comparison to raw WMS. Moreover, an economic cost estimation revealed that this approach could be an effective storage strategy for the efficient production of methane when employing a 1.7% (DM) urea application.

Attempts to improve the utilization of urea-treated whole-crop wheat by lactating dairy cows

This paper reports the results of three experiments designed to attempt to improve the efficiency of milk production from diets based on a 1: 2 dry matter (DM) mixture of grass silage and whole-crop wheat (WCW) harvested at 550 to 600 g DM per kg and treated with 40 g urea per kg DM. In the first experiment a control diet of the forage mixture offered ad libitum with 9 kg fresh weight (FW) per day of a concentrate mix was compared with seven treatments in which the forage or the concentrates were varied. Eight multiparous cows were used in a four-period incomplete change-over design with 4-week periods. Caustic treatment of the WCW increased DM intake (P < 0·001) but tendencies for higher yields of milk and milk protein were not significant. Replacement of 2 kg FW concentrates per day by the same weight of molasses as a 24-h pre-soak of the forage (molasses pre-treatment) or added to the forage at feeding increased DM intake (P < 0·001) but did not increase milk yield or yield of milk solids. Molasses pre-treatment and molasses added to the concentrates reduced milk protein concentration (P < 0·05). Replacement of 2 kg FW concentrates per day by the same weight of ground wheat increased DM intake when added to the concentrates (P < 0·001) but not when added to the forage and milk yield was unaffected by either method of addition. The ground wheat tended to reult in higher milk protein concentrations than the molasses. Increasing the digestible undegradable protein content of the concentrates had no significant effect on food intake or milk production. In the second experiment diet digestibility and energy and nitrogen (N) balance were measured for the control diet and three of the treatments from experiment 1 in four multiparous cows in a 4 ✕ 4 Latin-square experiment with 5-week periods. There were no significant effects on food intake or milk yield. Caustic treatment reduced starch digestibility (P < 0·001) and increased neutral-detergent fibre (NDF) digestibility (P < 0·05) but had no effects on energy utilization. It also reduced N intake (P < 0·01) and urine N losses (P < 0·001) by reducing the ammonia concentration of the WCW. Molasses added to the forage or concentrates reduced milk protein concentration (P < 0·05) and digestibility of both starch and NDF (P < 0·05) but energy utilization was unaffected. In a further Latin-square experiment with the same treatments and four fistulated lactating cows, caustic treatment reduced daily mean ammonia concentration (P < 0·01) and increased daily mean pH (P < 0·01) in the rumen. It is concluded that these treatments did not generally improve the value of WCW although caustic treatment increased milk yield and milk protein yield consistently but not significantly. However practical problems may limit its use on the farm. Urea-treated WCW must be accepted as being a relatively low-energy food although with high intake characteristics, and future work should concentrate on evaluating WCW harvested at an earlier stage of maturity.

Whole-crop wheat for dairy cows: effects of crop maturity, a silage inoculant and an enzyme added before feeding on food intake and digestibility and milk production

To measure the effect of stage of maturity of whole-crop (WCW) on its composition, digestibility and feeding value winter wheat was harvested at different maturities in two successive years. In year 1 WCW was harvested at 301(low dry matter (DM)) and 511(high DM) g DM per kg and ensiled and at 584 g DM per kg and treated with 40 kg urea per t DM before being stored (urea-treated WCW). Part of the high DM WCW was treated with an additive containing Lactobacillus buchneri at harvest. In year 2 WCW was harvested at 321 (low DM) and 496 (high DM) g DM per kg and ensiled before both crops were offered to the cows with or without a fibrolytic enzyme sprayed on the forage just before feeding. In both years the WCW was offered ad libitum in a 2: 1 WCW: grass silage DM ratio with 10 kg fresh weight concentrates per day to 40 early-lactation Holstein-Friesian cows in a 13-or 15-week production study with a continuous design and to four fistulated lactating cows in a 4 ✕ 4 Latin-square experiment for measurement of diet digestibility. In both years neutral-detergent fibre (NDF) content decreased and starch content increased with advancing maturity. In the production trials, DM intake increased (P 0·01) with advancing maturity but milk yield was not significantly affected. Milk protein yield was increased by urea-treated WCW. The additives had no effect on food intake or milk production. In year 1, digestibility of all fractions except starch was lower for high DM WCW than low DM WCW but for urea-treated WCW only the digestibility of starch and energy was lower than digestibility of the low DM WCW fractions. The inoculant had no significant effect. In year 2 crop maturity had no significant effect on digestibility but the enzyme reduced the digestibility of neutraland acid-detergent fibre (NDF and ADF, P 0·05). In year 1, each of the forage mixtures was offered to sheep at 12 g DM per kg live weight per day. There were significant treatment effects on the digestibility of DM (P 0·05) and organic matter (OM) (P 0·01) and on DOMD (digestible OM in the DM) (P 0·01) with the highest values being obtained for urea-treated WCW and the lowest for the inoculant-treated high DM WCW. Digestibility coefficients for NDF and ADF were highest for the urea-treated WCW while starch digestibility was essentially complete for all the WCW treatments. The metabolizable energy value (MJ/kg corrected DM) of the WCW decreased with advancing maturity when measured with both the lactating cows (10·4, 9·3 and 9·0) and the sheep (11·4, 10·8 and 10·3) in contrast to the predictions based on the chemical composition (9·6, 10·4 and 12·4). It is concluded that food intake increases with advancing crop maturity but milk production responses are small. Effects on digestibility were inconsistent but the energy value measured in the cows fell with advancing maturity in both years. The increase in crop yield per ha with advancing maturity is likely to be the most important factor influencing the decision to harvest later. The silage additives tested were not beneficial.

A comparison of the effects of cracked wheat and sodium hydroxide-treated wheat on food intake, milk production and rumen digestion in dairy cows given maize silage diets

To examine the effects of manipulating the amount and ruminal degradability of starch on food intake, milk production and digestion in the rumen of lactating dairy cows, cracked wheat (CW) and sodium hydroxide-treated wheat (SW) were compared when offered with either immature (IM) or mature (MM) maize silage given in a 3: 1 dry matter (DM) ratio with grass silage. The total mixed ration (TMR) contained (kg/t DM basis) forage 600, wheat (CW or SW) 170, rapeseed meal 100, soya-bean meal 100, molasses/urea supplement 30 and minerals and vitamins were added at 20 kg/t diet DM. In experiments 1 and 2 respectively, 16 multiparous Holstein-Friesian cows and four similar cows with duodenal and ruminal cannulas were offered four diets (IMCW, IMSW, MMCW, MMSW) in 4 ✕ 4 Latin-square designs. In experiment 3, the in sacco degradability of CW and SW was measured in the rumen of three lactating fistulated cows. In experiment 1 total DM intake was 0·7 kg/day higher and milk yield was 0·5 kg/day higher with MM than IM silage but the increases were not significant and type of wheat had no effect. Milk fat content was reduced by MM silage (P < 0·05) but was unaffected by type of wheat. For milk protein content SW caused a non-significant increase with IM but a decrease (P < 0·05) with MM silage (interaction P < 0·05). There were no significant effects on yield of fat or protein. Neutral-detergent fibre digestibility in the rumen was unaffected by the treatments. Starch intake increased (P < 0·05) with MM silage when compared with IM silage and was accompanied by an increase (P < 0·01) in starch flow to the duodenum and in the amount (P < 0·001) digested in the rumen, although there was no significant change in rumen digestibility. Replacing CW with SW increased starch flow to the duodenum (P < 0·05) and reduced rumen digestibility (P < 0·05). Although the amount of total nitrogen (TN) digested in the rumen and rumen digestibility decreased (P < 0·01) with crop maturity, the flow of TN and non-ammonia nitrogen to the duodenum was unaffected. Total tract digestibility of DM was unaffected by treatments. Although the amount of starch digested in the total tract increased for MM compared with IM silage, reflecting the higher starch intake, total tract starch digestibility was unaffected by treatment and averaged 0·972. There were no main treatment effects on daily mean pH, concentration of ammonia or concentration or molar proportions of volatile fatty acids in the rumen. With SW, effective degradability (outflow rate of 0·08 per h) for both DM and starch was reduced when compared with CW. In conclusion the studies confirm that SW is more slowly fermented than CW and can increase the supply of starch to the duodenum. However the concept that increasing starch supply to the duodenum by a combination of MM silage and SW is likely to be beneficial to milk protein yield or concentration is not established under the present dietary regimen.

The performance of dairy cows offered ensiled whole-crop wheat, urea-treated whole-crop wheat or sodium hydroxide-treated wheat grain and wheat straw in a mixture with grass silage

Twenty-four Holstein Friesian cows in experiment 1 and 40 cows in experiment 2 were used over 12 weeks in continuous designs, to evaluate winter wheat as a forage for dairy cows. In experiment 1, whole-crop wheat was ensiled at 350 g dry matter (DM) per kg (EW) or harvested later and stored at 550 g DM per kg following treatment with 40 g urea per kg DM (40W). In addition to these treatments in experiment 2, whole-crop wheat of 550 g DM per kg treated with 20 g urea per kg DM (20W), and combine harvested wheat grain plus wheat straw (40: 60 ratio) treated with sodium hydroxide (SG) were also included. These whole-crop wheat forages were incorporated into the diet at a level of 400 g/kg of the forage DM in experiment 1, and 330 g/kg in experiment 2, with the remainder of the forage being grass silage. A control treatment of grass silage (GS) offered as the sole forage was also included. The forages were mixed in a mixer wagon and offered ad libitum. A fixed level of 8 kg/day of concentrates was offered in experiment 1 and 7 kg/day in experiment 2. Total DM intake was significantly greater for EW and 40W than for GS in experiment 1, but not in experiment 2. Milk yield was not significantly affected by diets (mean 28·8 kg/day in experiment 1 and 29·6 kg/day in experiment 2). Milk fat, protein and lactose contents and yields were also not significantly affected by diets. The additional total metabolizable energy (ME) intake of the whole-crop diets compared with GS was partitioned to live weight. There was no evidence of ME intakes being substantially greater than ME requirements as found in previous studies. A 5 × 5 Latin square digestibility experiment was carried out with Holstein-Friesian heifers offered the individual forages used in experiment 2. Intake was significantly greater for the urea-treated whole-crop wheat forages than for grass silage and for sodium hydroxide-treated grain and straw. The digestible organic matter in the dry matter (DOMD) of grass silage was 692 g/kg and the whole-crop wheat diets ranged from 626 g/kg for ensiled whole-crop wheat to 682 g/kg for the sodium hydroxide-treated grain plus straw (40: 60 ratio), with the DOMD of urea-treated whole-crop being intermediate. The results indicated that whole-crop wheat had higher intake characteristics than grass silage in spite of its lower digestibility.