GB2320410A

GB2320410A - Animal feed containing a lignin-urea product

Info

Publication number: GB2320410A
Application number: GB9626608A
Authority: GB
Inventors: Castro Fernando B De
Original assignee: Rowett Research Services Ltd; Norsk Hydro ASA
Current assignee: Rowett Research Services Ltd; Norsk Hydro ASA
Priority date: 1996-12-20
Filing date: 1996-12-20
Publication date: 1998-06-24
Also published as: WO1998027830A1; EP0957689A1; PL334299A1; GB9626608D0; CA2275031A1; BR9714154A; AU7870098A; ZA9711463B

Abstract

The present invention relates to ruminent feed comprising urea, slow release urea feed supplement and a method for preparation of said feed supplement. The ruminent feed comprises 0.5-5 weigth% diet dry matter of urea as a lignin-urea (LU) product. The preferred ratio lignin:urea in the LU product is 75-15 : 85-25. The slow release urea supplement feed comprises said LU product, which may contain additives such as starch lanolin, glycine, paraffin, and/or polyethylene glycol. The LU product may also be coated. The slow release urea product can be prepared by mixing lignin with solid urea at 130-200{C at pressures of 1-10 bar and at a retention time of 0.5-30 minutes. The resulting lignin-urea product is crushed or milled to desired size.

Description

Title: Ruminant feed comprising urea, a slow release urea supplement feed and a method for preparation of said supplement feed.

The present invention relates to ruminant feed comprising urea and a slow release urea supplement feed, which can be used in ruminant feed. The invention also comprises a method for preparing said feed supplement.

Urea is widely used as a non-protein nutrient nitrogen source for ruminants enabling the ruminants to balance the rumen microbes carbon and nitrogen requirements without using expensive protein nutrient sources However, unprotected urea in the rumen is rapidly metabolised by rumen microbes with any excess nitrogen being released as ammonia. This limits the use of high concentrations of urea in the feed as rumen ammonia concentration would rapidly reach toxic values shortly after intake. Accordingly, the urea should be released slowly to get a more even ammoniawnitrogen concentration during at least the first eight hours after feeding in order to give the rumen the ability to utilise the urea efficiently.

Several attempts have been made to develop feeds comprising urea which is slowly released, but most of these have failed for different reasons such as high cost, unacceptable additives and inefficiency with regard to release rate of urea .

From EP 0 716.056 Al there is known a method for producing slow-release nitrogenous organic fertilizer from biomass. Ligno-cellulosic materials and starchy materials selected from the group consisting of agricultural waste, forestry waste, municipal waste, wood, grasses etc are subjected to pyrolysis and the products thereof are chemically combined with a nitrogen compound containing NH2 (amino) groups, such as urea, aqueous solutions of urea, ammonia, amine and ammonium salts. Though this fertilizer product may give some slow release effect when applied in the soil, it is not known to be used in rumen feed. A somewhat similar product is known from EP 0 007.136 Al. This application describes a cattle fodder from partially hydrolysed ligno-cellulosic material and urea. The fodder is prepared by hydrolysing, straw, bagasse or other lignoveellulosic by-products with diluted acid, and subsequently condensing said prehydrolysed material with urea. The total nitrogen content of the raw product indicated that it contained nearly 100% of the urea added at the start. Of this urea, 67% was shown to be slow release urea while 33% was present as free urea. The ligno cellulosic material is treated to hydrolyse at least a major part of the hemicellulosic portion thereof into reducing saccharides prior to its contact with a urea solution before the mixture is heated to bind the urea. The prehydrolysis takes about 24 hours at 90-130"C and the heating to effect the condensation with urea 2-5 hours at 70-1 000C. The process is rather expensive and the amount of urea in the product, as slow release urea, is low making the product, on a urea basis, expensive.

From GB-Patent 1.502.411 there is known a process for obtaining slow release of biologically active materials, especially pesticides. A composition comprising an intimate mixture of an organic polymer and a biologically active component. Thus it is abtained a gradual release of the pesticide to the environment which said composition is exposed to.The polymer is selected from thermoplastic polyamides, kraft lignin, asphaltic resins, polyvinylacetate and natural occurring polymers.

The main objective of the invention was to arrive at a feed supplement comprising urea which would release the urea in the rumen slowly and gradually such that undesired high ammonia concentrations in the rumen could be avoided.

Another objective was to produce rumen feed comprising feed supplement that could endure the process condition used for complete feed preparation.

A further objective was to produce a feed supplement that could be utilized together with low nitrogen to carbon ratios such as hay, straw etc, It was also an objective to arrive at an economical and simple process for making the feed supplement from available raw materials.

In his search for finding a solution to the above stated problem the inventor evaluated previous attempts to make slow release urrea, both within the fertilizer field and the rumen feed field. The main problem was to select a material that could encapsulate or bind urea in such a way that urea would be released slowly and gradually in the rumen. Among all such materials previously tested some were obviously unacceptable as feed components. Another problem was to select a material that was readily available at a reasonable price and which would not cause any adverse effects during processing and use. One possible useful material was lignin which is available from various sources. According to the above referred GB-Patent one type of lignin, kraft lignin, could be used to make products containing pesticides which then would be released slowly during application of said products. The question was then whether lignin could react with urea in manner which would encapsulate relatively large amounts of urea which subsequently could be released slowly in the rumen. In order to test this idea of making a lignin-urea (LU) product preparation of such products were started. During the initial tests kraft lignin was used as the lignin source. However, other types of lignin were also found useful. It was found that urea reacted with the lignin when the two components were mixed together at high temperatures.

The LU products for the present tests were prepared at 158"C or 170"C and atmospheric pressure. However, the preparation of useful LU products could also be obtained at other temperature and pressure conditions.

Various types of lignin coming from different sources could be applied. Thus the lignin could be obtained from straw, sugar cane bagasse or eucalyptus, the raw lignin source being subjected to auto hydrolysis at temperatures above 170"C and subsequently washed with water and subjected to alkaline treatment and finally acidification (HCI). The resulting solid lignin fraction was precipitated and centrifuged and had a typical analysis of more than 90% lignin content. The contaminants will mainly be ash, sugar and some cellulose. When this lignin product was melted together with urea at for instance 158or, a rather viscous homogenous LU product would be obtained. The LU product tumed solid as it was cooled at ambient temperature. The hard LU product was crushed or milled and desired particle size was obtained by sieving.

Further tests showed that LU products with different lignin:urea ratios in fact gave a marked reduced release of urea in rumen.

Application of additives, defined as chemical substances other than urea and lignin in the product formulations, at levels lower than the lignin content, were also investigated and found to result in greater control over the rate of urea release.

Lanoline was shown to have such effect, especially when applied as a coating.

Provided that the lignin coating can endure the conditions for producing feed containing such coated LU feed supplements, this will be a useful procedure for obtaining the desired slow release urea containing feed.

A ruminant feed according to the invention comprises 0.5-5 weigth% diet dry matter of urea as lignin-urea (LU) product. Preferred ratio lignin:urea in the LU product would be 75-15 : 85-25 In order to further improve the slow release properties of the feed, a coating can be applied on the LU product. Lanolin is found to be a suitable coating.

A slow release urea supplement feed comprising a lignin-urea (LU) product is also developed. This supplement feed containing the LU product can be applied in said ruminant feed, but also together with hay, straw etc. The LU product may contain additives, such as starch, lanolin, glycine, paraffin andlor polyethyleneglycol (peg), to improve the performance of the product in the rumen.

The preparation of the slow release urea product can be performed by mixing lignin with solid urea at temperatures of 130-200"C, pressures of 1-10 bar and at retention times of 0.5-30 minutes. The resulting LU product will be milled or crushed to desired size. The lignin can be made from raw lignin subjected to auto hydrolysis at temperatures above 1 70 > C, washing, alkaline treatment and acidification. The resulting purified lignin is precipitated and separated as a product containing more than 90 weigth% lignin, the rest being ash, sugar and some cellulose.

The invention will be further envisaged and explained in the following examples: Example 1.

This example shows the release rate of urea from LU formulations as a function of particle size and lignin:urea ratio.

Three LU formulations containing different ratios of urea and lignin were prepared at both 158"C and 170"C. The LU formulations and analysis of end products are shown in table 1.

Table 1

Sample Target Temp. N content Actual % number urea ( C) % urea 1 25 1158581228 26.34 2 35 - 158 17.16 36.81 3 45 158 21.97 j 47.13 4 25 170 12.72 27.28 5 35 170 16.36 35.09 6 45 170 20.95 44.94 7 1 25 170 12.20 26.17 Each formulation was then separated into different physical sizes and tested for urea release characteristics over 48 hours using artificial saliva incubation tests.

The release of urea from LU was assessed by incubating a series of flasks with 0.29 LU and 1 00ml artificial saliva at 39 C in a cradle with gentle stirring. Flasks were analysed throughout the incubation time chosen for the study. The artificial saliva buffer was prepared according to McDougal,( El. Biochemical Journal, 43, 99-109, 1948), though without CO2 saturation of the dilute solutions. Samples were tested both with artificial saliva adjusted to pH= 6 by addition of o-phosphoric acid, and unadjusted saliva with pH=8.3. The physical sizes of LU were: Pellet equivalent to an average size of 3x3 mm Ground capable of passing through a 250 Fm sieve Small pellet equivalent to an average size of 3x3 mm Medium pellet equivalent to an average size of 4x4 mm Large pellet* equivalent to an average size of 5x5 mm products prepared from sample no 7 in table 1.

Urea release data from each LU formulation obtained using the artificial saliva test, as urea released as % of potential as function of incubation time in hours, are shown in table 2.

Table 2.

Sample No, & 1h 2h 4h 8.2h 12.2h 24h 48h Physical Form 1 pellet 31.6 44.6 56.4 71.3 77.8 87.1 87.1 2 pellet 52.7 72.3 84.3 89.7 93.1 87.9 89.6 3 pellet 61.7 85.3 95.5 96.9 95.7 96.4 93.8 1 ground 85 8 89.0 86.3 88.2 87.8 85.1 87.2 2 ground 92.2 91.2 89.3 86.1 90.2 89.2 88.6 3 ground 92.5 92.5 91.2 91.7 86.5 88.5 88.5 4 pellet 31.1 42.9 58.5 71.7 79.2 83.2 85.2 5 pellet 42.4 58.1 74.9 87.7 89.3 84.8 89.2 6 pellet 74.3 86.7 89.1 89.6 88.9 87.9 87.8 6 pellet 74.3 86.7 89.1 89.6 88.9 87.9 87.8 4 ground 88.1 86.9 82.5 84.4 85.7 83.9 82.4 5 ground 91.0 89.3 86.5 87.8 83.8 85.0 85.5 ground 93.2 91.1 88.5 88.6 87.4 89.0 86.8 7 small pellet 87.5 86.1 80.0 78.9 73.2 80.8 80.5 7 med. pellet 70.2 78.1 80.8 83.6 83.2 82.2 83.4 7 large pellet 40.4 45.0 56.0 67.7 76.5 80.4 83.4 Sample No. 1-7 relates to sample No. in table 1.

Table 2 shows that the release rate is high for all LU formulations when the LU products are ground. For large pellets the release rate is low and increasing slowly the first four hours. It is further shown that the release rate decreases significantly with increasing content of lignin in the LU formulations.

Example 2 This example shows comparison of urea release from LU formulations with varying urea:starch:ignin ratios. Four LU formulations containing different ratios of urea, starch and lignin were prepared at 1700C and this is shown in table 3.

Table 3

Sample Urea Starch Lignin N content Actual % number urea 1 35 5 60 17.62 37.79 2 35 10 55 17.42 37.37 3 45 5 50 21.63 46.40 4 45 10 45 21.44 45.99 Each LU formulation was then tested for urea release characteristic over 48 hours (incubation time) by the use of the saliva procedure. The results are shown in table 4. Urea released are given as % of potential maximum.

Table 4

Sample 1 2 4 8 11 24 48 number 1 58.8 76.7 91.0 91.5 92.9 93.1 93.4 2 71.9 87.8 90.4 90-7 91.0 90.7 91.6 3 75.8 88.7 92.7 92 4 90.0 91.9 97.8 4 58.2 77.3 86.2 86.3 85.2 87.5 85.6 These results shows that there is little effect of substituting lignin with starch and that the content of lignin has the greatest effect on urea release. Further tests showed that coating of the LU particles with lanolin substantially reduced the urea release rate.

Example 3 This example shows the effect on ammonia nitrogen levels in rumen fed with diets containing 2% urea present as urea or LU comprising 65% lignin. The effect on rumen pH I was also recorded. The effect on rumen pH was however, negligible which is a positive indication that nitrogen was not being released as ammonia in high, i. e. toxic, amounts. The dietary regimes severe: a) General purpose (GP) diet only (i.e. no added urea or LU) fed orally.

b) GP diet plus 2 urea (urea control diet) fed orally.

c) GP diet plus 2% urea present as LU product fed orally d) GP diet plus 2% urea present as LU product with the GP fed orally and the LU component poured directly into the rumen.

The point of regime d) was to avoid any effect of chewing which could be a factor when the same diet was fed orally.

Three sheep were used, each was fed the GP diet in the first rotation to get background data and then the three test regimes with added urea were applied to the sheep using a Latin square experimental protocol. The average rumen ammonia-nitrogen levels (mg/l) for each dietary regime over the 8 hours period (time zero being immidiately prior to feeding) are given in table 5 and shown graphically in figure 1.

Table 5.

Sampler Diet: GP Diet:GP + LU Diet: GP+LU time (h) + urea oral rumen 0 132.10 231.30 144.40 1 489.70 324.10 340.40 2 65180 430.60 395.90 4 372.50 416.60 433.30 8 204.70 294.40 263.70 As can be seen from table 5 and fig. 1 rumen ammonia-nitrogen concentration reached a peak value about 650mgiml after 2 hours when ordinary feed urea was used. Contrary to this, feeds containing the new LU product gave a far more gradual release of urea. Furthermore, both LU test regimes exhibited similar urea release characteristics with peak urea concentrations, in the rumen being almost half the peak values of the feed containing unprotected urea. The LU products have accordingly potential to protect against ammonia toxicity.

Example 4 This example shows application of LU products together with hay compared to different sources of urea. Comparative effects on ammonia-nitrogen concentration in rumen liquor incubated in vitro with hay and the various urea sources are given. Furthermore, the positive effect of an additive, lanolin, coated onto the LU product, is shown. Treatments used to ascertain the effect of different presentations of urea on the ammonia-nitrogen concentration in rumen liquor were: 1 Hay only 2 Hay + pure urea.

3 Hay + LU as used in feeding trials (expamplel) 4 Hay + LU with 25% urea 5 Hay + LU with 25% urea coated with lanolin.

The average in vitro ammonia-nitrogen concentrations (mull) for each treatment are given in table 6. The incubation time in hours varies from 1 -24 hours.

Table 6

Treatment 1h 2h 4h 8h 12h 24h 1 170.0 171.3 191.1 203.7 213.8 291.5 2 213.4 234.3 245.9 255.9 269.9 334.2 3 199.1 219.3 247.0 261.1 273.9 336.2 4 189.9 198.5 231.4 251.1 268.4 343.1 5 177.7 184.6 216.0 239.3 256.2 345.3 2* 43.5 63.0 54.0 52.2 56.1 42.7 3* 29.1 48.1 55.2 57.4 60.1 44.8 4* 20.0 27.2 39.5 47.4 54.6 51.6 5+ 7.7 13.4 24.1 38.6 42.4 53.8 - values subtracted the control data (treatment 1).

This example shows that hay plus pure urea gave far higher initial ammonia values than any of the LU treatments. Furthermore this example confirms the ammonia- nitrogen suppressing ability of the LU products is greater when the lignin content is greater (treatment 3 versus treatment 4) and that the lanolin coating is an effective method of enhancing the LU effect (treatment 4 versus treatment 5).

Further experiments showed that the functional specific gravity of the LU products can be an important factor in determining the utility of the products. It is essential that the urea containing feed stays in the rumen for a minimum time and this can be influenced by adjusting the specific gravity of the LU product. Firstly, higher specific gravity can be obtained during the production of the LU product itself by operating at conditions reducing the void fraction. Secondly, various gravity increasingldecreasing components can be incorporated in the LU product.

From the above experiments it can be seen that the inventor has succeeded in arriving at a new feed supplement containing urea which is slowly released in the rumen. The new LU product can be incorporated in compound feedlconcentrates for ruminants or used as a feed supplement together with hay, straw etc.

The known protection ability to protein of lignin has also been retained by the LU products according to the invention Application of the new products can reduce substantially the risk of ammonia toxicity of ruminants fed urea containing feed.

Claims

1. Ruminant feed comprising urea, characterized in that the feed comprises 0.5-5 weigth% diet dry matter of urea as lignin-urea (LU) product.

2. Ruminant feed according to claim 1, characterized in that the ratio lignin: urea in the LU product is 75-15: 85-25.

3. Ruminant feed according to claim 1 characterized in that the LU product is coated prior to incorporation in the ruminant feed.

4. Ruminant feed according to claim 1, characterized in that the LU product is coated with lanolin prior to incorporation in the ruminant feed.

5. Slow release urea supplement feed, characterized in that the slow release urea comprises a lignin-urea (LU) product.

6. Slow release urea supplement feed according to claim 4, characterized in that the ratio lignin:urea in the LU product is 75-15: 85-25.

7. Supplement feed according to claim 4, characterized in that the LU product comprises an additive, such us starch, lanolin, glycine, paraffin andlor polyethyleneglycol, to improve the performance of the product in the rumen.

8. Supplement feed according to claim 4, characterized in that the LU product is coated, preferably with lanolin.

9. Method for preparation of a slow release urea product, characterized in that lignin is mixed with solid urea at temperatures of 130-200 C and at pressures of 1-10 bar and that the retention time is 0.5-30 minutes, and that the resulting lignin-urea (LU) product is crushed or milled to desired size.

10. Method according to claim 8, characterized in that the lignin is made from raw lignin subjected to auto hydrolysis at temperatures above 1700C, washing, alkaline treatment and acidification and that the resulting purified lignin is precipitated and separated as a product containing more than 90 weigth% lignin, the rest being ash, sugar and some cellulose.