Evaluation of straw treatment with ammonia sources on growing bulls

ANIMAL FEED SCIENCE AND TECHNOLOGY

EUEVIER

Animal Feed Science Technology 60 (19961 117-130

Evaluation of straw treatment with ammonia sources on growing bulls G. Flachowsky

* A,

W.I. Ochrimenko, M. Schneider, G.H. Richter

Institute of Nutrition and Environment, Faculty of Biology and Pharmacy, Friedrich-Chiller-University Dornburger Str. 24, D-07743 Jena, Germany

Jena

Accepted 30 August 1995

Abstract Energetical and ecological aspects of straw ammoniation were calculated based on five feeding trials with growing bulls consuming untreated, ammonia or urea treated wheat straw. Dry straw was gased with ammonia (3.0-3.2%) and wet straw (38.1-56.3% dry matter, DM) on DM base). In digestibility experiments with sheep and feeding was treated with urea (255% trials with 104 growing bulls fed treated and untreated straw was compared. Bulls consumed 2 kg concentrate per day and untreated or treated straw ad libitum. In two experiments ammonia or urea treated straw was given in adequate amounts to untreated straw (pair feeding). Based on the results of feeding trials energetic input (60 or 80 MJ per kg N from ammonia or urea) and ecological output (NH,, CO,) were calculated. Ammoniation increased apparent digestibility of organic matter of wheat straw from 43.9 to 52.7%, urea treatment enhanced it from 46.5 to 53.0% on average. Pair feeding of ammonia or urea treated wheat straw resulted in an increase of daily liveweight gain amounting 69 and 55 g day-‘. Ad libitum intake of treated straw increased daily weight gain with range of 75 to 290 g. Animal growth rate was used to evaluate the different straw treatments with regard to the ammonia sources. Between 0.8 and 7.0 kg body weight were produced per kg N added to the straw due to higher digestibility and increased straw intake. Assuming a conversion rate of 5 kg grains for 1 kg beef, one kg N used as fertilizer has at least to increase the yield of cereals in the range of 3.8 and 35 kg, otherwise the N-utilization on the field would be less efficient. Low animal response to ammoniation of straw resulted in high fossil energy needs per animal and high environmental pollution. More dose-response trials are necessary to allow a better evaluation of N-efficiency in straw treatment.

* Corresponding author. Tel.: 03641 637079, Fax.: 03641 424307. ’Present address: Federal Research Centre of Agriculture, Institute of Animal Nutrition, D-38 116 Braunschweig,

Germany.

0377.8401/96/$15.00 0 1996 Elsevier Science B.V. All rights reserved SSDI 0377.8401(95)00915-9

Bundesallee

50,

118

G. Flachowsky et al./Animal Feed Science Technology 60 (1996) 117-130

Keywords: Cattle-growing; ical aspects

Wheat straw; Ammonia

treatment; Ammonia

treatment-energetical

and ecolog-

1. Introduction

Lehmann, 1905 patented the ammonia treatment of low quality roughages for upgrading the feed value of cereal straws. Later, further experiments with ammonia treatment of straw and other fibrous feeds were carried out (e.g. Kronberger, 1933, Nikolaeva, 1938, Oehme and Hen-mum 1943, Juncker, 1984). This area has been extensively investigated, including aspects of straw intake, digestibility and performance of ruminants fed low quality roughages treated with ammonia, urea, urine and other NH, sources and recently reviewed by many authors (e.g. Chenost and Reiniger, 1989, Flachowsky, 1987, Galletti, 1991, Sundstol, 1988, Sundstol and Owen, 1984). Ammonia sources are not so efficient in increasing feed value of low quality roughages as NaOH, but they contribute N for rumen microbes and could prevent mould. Most of the authors compared effects of ammonia treatment with untreated roughages. Sometimes economical considerations (e.g. Eldelsten and Lijongwa, 1981, Schiere and Nell, 1993, Schiere and deWit, 1995) for using low quality roughages are given. No attention has been paid on the amount of fossil energy needed for ammonia or urea synthesis. Furthermore many authors neglected ammonia losses or pollution problems associated with the ammonia treatments. Rifkin (1994) criticizes cattle because of their inefficient conversion of feeds into food for human nutrition and pollution problems. Therefore it seems to be urgently necessary to analyze and quantify all expenditures especially if these treatments are recommended for tropical and subtropical countries. Ammonia or urea may also be used as fertilizer and may increase the yield of grain and forage. This alternative to increase the feed supply of ruminants has to be compared with straw treatments with regard to their effectivity. So-called life cycle studies (Nierynck, 1993) include inputs (e.g. requirements of fossil energy for production) and outputs (e.g. pollution with NH, or CO,) for production of substances (e.g. ammonia or urea). In future that life cycle studies are urgently necessary for evaluation of the different activities in human being. The objective of the present study is to calculate the effectivity of wheat straw treatment with ammonia or urea in beef cattle feeding.

2. Material and methods Digestibility experiments with sheep and five feeding trials with growing cattle fed untreated and urea or ammonia treated wheat straw were used to evaluate this technique considering nutritional-economical and ecological aspects. The methods of animal experimentation and the results of the digestibility experiments and feeding trials are described in a short version only. Details can be seen by Ochrimenko (1984) and Schneider (1988).

G. Fiachowsky et al./Animal

Feed Science Technology 60 (19961 117-130

119

Table 1 Crude nutrient contents (g kg-’ DM) and apparent digestibility of organic matter (o/o) of untreated and ammonia or urea treated wheat straw Exp. Exp. series No.

Wheat straw charge

A

Untreated Treated with 3.2% ammonia Untreated Treated with 3% ammonia Untreated Treated with 3% urea Unueated Treated with 4% urea Untreated Treated with 2.5% urea Treated with 5% urea

Dry matter

Crude protein

Crude carbohydrates

Crude ash

Fixed N Apparent (Percentage digestibility of added N) of organic matter

38 63 39 74 49 64 50 105 56 95 110

867 850 895 858 844 843 870 805 867 821 799

86 80 51 54 94 87 75 84 57 65 70

15.2 22.6 17.4 47.1 53.5 37.0

(g kg-‘)

I II

B

I II III

870 860 913 923 802 381 817 465 909 563 556

44.5 + 4.0 52.0 + 4.0 43.2f2.3 53.4k2.8 45.3k3.6 47.6k3.3 46.0+4.1 49.4k8.0 48.1+ 4.9 56.5 + 4.3 58.5 -I 4.9

2.1. Straw treatment Winter wheat straw of the variety “Alcedo” was used for all experiments. In the experiments of series A the dry wheat straw was chopped (3-8 cm), weighed and stored in a large stalk (20 X 10 X 30 m). Ammonia was injected by a lance into the straw as described by Sundstpll(1983/84), and modified by Flachowsky et al. (1984/85). The untreated straw was stored in a barn. In the experiments of series B rain wet straw was harvested under farm conditions (dry matter content: 38-56%, Table l), chopped and weighed. It was homogeneously mixed with various amounts of urea (2.5-5% on DM base) and stored in a large scale silo (10 x 30 x 3 m) like silage. Before covering with plastics it was compressed with a large tractor. Experiments were repeated in three years. Immediately before raining untreated straw was harvested and stored in a barn. Table 1 shows the composition of the untreated and treated straw charges. 2.2. Digestibility

experiments

From all straw charges digestibility was determined with castrated male sheep of the Merino breed according to the recommendations given by Schiemann (1981). Five sheep with an initial body weight of 50 + 3 kg were housed in individual pens and fed at maintenance level (l.O- 1.3 X maintenance). The animals were kept free from internal and external parasites. Rations consisted of 500 g dry straw (untreated or ammonia treated) or wet urea treated straw in the range from 800 to 1200 g as dependent on their dry matter content (see Table l), 250 g artificially dried ryegrass and 250 g concentrates including minerals and vitamins. Sheep were fed twice a day. After 18 days of adaptation, faeces and urine were collected over a 10 days period and later analyzed. The digestibility of the untreated and differently treated straw charges was determined applying the difference technique.

120

G. Flachowsky et al. / Animal Feed Science Technology 60 (19961 I I7-130

2.3. Feeding experiments

Five feeding experiments with growing bulls of the Black and White Dairy Breed were carried out (Table 2). Bulls were kept on concrete floor with sawdust as bedding. They were individually fed with untreated or treated straw. The bulls consumed 2 kg concentrate (exp. A I: beginning with the 140th day 3 kg were fed) per animal per day and untreated or ammonia/urea treated wheat straw was offered ad libitum. Table 2 shows the experimental design and the composition of the concentrate. Untreated straw was offered ad libitum in all experiments. To feed the rations isonitrogenous urea was added to rations with untreated straw. In experiments A I and B I ammonia or urea treated straw was offered at the same amount of untreated straw consumed ad libitum (pair feeding). In both experiments each animal, which was fed with untreated straw ad libitum was individually paired with an animal fed adequate amounts of ammonia or urea treated straw based on DM intake. The objective of those experiments was to quantity the effect of digestibility improvement associated with ammonia or urea treatment of straw on animal growth. All the bulls where weighed individually at the beginning, after 28 days and at the end of the experiments. Further details of the feeding experiments are given in Table 2. 2.4. Fundamentals of energetical and ecological calculations

Energetical costs of ammonia or urea synthesis were used for calculation. Fossil energy needed to fix 1 kg N as ammonia varied between 40 MJ ( > 1 1 diesel fuel, Fink, 1992) and 88 MJ (Dovring and McDovell, 1980, Kohlmeyer, 1986, Pimentel et al., 1990). Helsel (1992) calculates the amount of 55.3 MJ per kg of N for ammonia synthesis. Urea production requires 76.3 MJ per kg of N. Approximately 25% of this energy is necessary for synthesis and prilling of the urea from ammonia feedstocks (Helsel, 1992). Packaging, transportation of raw materials and products, and application of different N-sources (Mudahar and Hignett, 1987) are not considered. For the calculations in Table 3 about 60 MJ or 1.5 1 diesel fuel per kg N from ammonia and 80 MJ or 2 1 diesel fuel per kg N from urea are used. Ammonia or urea consumption for straw treatment was measured (Table 2). Multiplication of the amount of ammonia or urea added to the straw and the straw intake of bulls leads to the quantity of urea or ammonia, which is needed each day. The higher daily weight gains of bulls due to treated straw feeding was used for evaluation of both N-sources. In the balances N-input associated with straw treatments was compared with the increased N-accretion in the weight gain as output. In order to feed isonitrogeneous rations corrections had been made for urea supplementation of untreated straw. The efficiency of the straw treatment with N-sources (weight gain per kg added N) was compared with the effects, which were achieved on the yields of grain or forage, when this N-amount is used as fertilizer. Carbon dioxide losses associated with ammonia or urea synthesis as well as ammonia losses during storage and straw feeding were considered as environmental factors. Based on the energy costs for synthesis and CO, output, both environmental factors, were calculated as depended on the quantity of ammonia or urea added to the straw (Table 3).

” Ingredients

II

treatment)

of concentrate:

III

I

(“urea

1

II

2 1 2 3

1

21

L

1 2 3

1

A (Ammonia treatment)

9 9 7 7 7 I 10 9 9

10

12.5 9.3 10.6 14.2 13.5 10.5 12.0 11 .I 8.8 15.2 19.1 14.2

193.0* 193.3 f 193.6 f 205.0 i 205.5 * 156.4+ 156.6f 235.1 f 235.0+ 237.9+ 237.2& 231.6 f

10

IO

Initial body weight (kg per animal)

Number of animals

168

252

252

112

336

(days)

Duration of experiments

35% wheat, 35% barley, 4% dried sugar beet, 20% soybean

Groups

Exp. No.

design

Exp. series

Table 2 Experimental

meal, 6% urea-mineral-vitamin

premix.

Untreated, ad lib. Treated with 3.2% NH, pair fed to group Treated with 3.2% NH,, ad lib. Untreated, ad lib. Treated with 3.0% NH,, ad lib. Untreated, ad lib. Treated with 3% urea pair fed to group 1 Untreated, ad lib. Treated with 4% urea, ad lib. Untreated, ad lib. Treated with 2.5% urea, ad lib. Treated with 5% urea, ad lib.

Wheat straw (NH A or ureatreatment on DM-base)

Feeding

1

2

2

2

2

2 or 3 kg before and after 140” day

Concentrate a (kg per animal per day)

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G. Flachowsky et al./Animal

Feed Science Technology 60 (1996) 117-130

2.5. Chemical and statistical analysis

Samples of feeds and faeces were collected and prepared for the determination of DM, nitrogen, crude fibre, ether extract and crude ash according to proximate analysis (AOAC, 1982). Crude carbohydrates were calculated as difference between DM and crude ash, crude protein and ether extract. Cell wall constituents of the feeds were determined by the detergent method described by Goering and van Soest (1970) and modified by Schneider et al. (1989). Data were subjected to variance analysis. The differences between treatments were tested using Tukey Test for a confidence level of P < 0.05 (LSD, Least Significant Difference).

3. Results and discussion 3.1. Straw composition and digestibility

As expected, ammonia or urea treatment increased the N content of wheat straw significantly (Table 1). The increment varied from 1.3 to 2.1 times of untreated straw (6.1-9.0 g N kg-’ DM). From the added N between 15.2 (exp. A I) and 53.5% (exp. B III) was fixed in the straw and seems to be available for microbial protein synthesis in the rumen. Rations of bulls fed with untreated straw were supplemented with urea to keep the rations isonitrogeneous (Table 4). Difference of N to 100% was lost during storage. Highest N losses were registered after ammoniation (84.8%, Table 1). Due to of the affinity of NH, the N-amount bound in the straw increased with moisture contents excepting of exp. B I.

Table 3 Model on the influence

of ammonia

or urea supplements

on fossil energy ’ requirements

Level of added ammonia source to straw

Fossil energy (MJ kg- ’DM)

(percent of DM)

Ammonia

Urea

_

_

0.5 1.0 1.5 2.0 2.5 3.0 4.0 5.0

0.4 0.7 1.1 1.4 1.9 2.2 3.0 3.1

0

1 2 3 4 5 6 8 10

a 1 1fuel was calculated to contain = 42 MJ (Cervinka, were developed during burning of 1 kg diesel fuel.

and CO*-output

co*-output (g kg- ’ DM)

1980, Kohlmeyer,

Ammonia

Urea

31 62 93 124 15.5 186 248 310

24 48 13 97 121 146 194 243

1986, Reinhardt,

1993); 2.6 kg CO,

I:2 I:3 1:2 I:2 I:2 1:2 1:3

AI

A II BI B II B III

Comparison of groups

of ammonia

Exp.

Table 4 Efficiency

69 74 290 55 259 190 245

Weight gain increase of bulls fed with treated straws (g animal- ’day-

or urea

’) 128 145 1.52 94 205 134 276

Ammonia/urea needed for straw treatment (g day- ’)

34 46 56 16 96 74 102

Urea supplements to untreated straw to formulate isonitrogenous rations (g day ’) 1.3 1.3 0.34 0.66 0.20 0.14 0.33

kg N per kg increase weight

N-efficiency

0.11 0.76 2.9 I .5 5.1 7.0 3.0

kg increased weight gain per kg N

124

G. Flachowskyet al./Animal Feed Science Technology60 (1996) I1 7-130

If the treated straw has been aerated before feeding, the total N content declined to relatively constant values of 10 to 19 g kg- ’ DM, regardless of the content before aerating. Similar N-losses have been reported by Becker and Pfeffer (1977), Dryden and Leng (1986) and Schneider and Flachowsky (1990). Apart from crude protein increase, ammonia or urea treatment decreased fibre contents of straw (Table I>. Similar results are reported by Schneider and Flachowsky (1990). Hemicellulose is the fraction, which is mostly affected by the ammonia treatment. It has been suggested that parts of the hemicellulose are dissolved (Horton, 1981, Saenger et al., 1983). The increase of free carboxyl groups due to cleavage of the ester bonds of uranic acids in the hemicellulose (Terashima et al., 19841, the reduction of uranic acid residues (Graham et al., 1985) and the loss of acetyl groups indicate chemical changes in the hemicellulose fraction. Treating straw with ammonia increased apparent digestibility of organic matter (Table 1) and fibre varying between 2.3 (exp. B I> and 10.4% (exp. B III) due to the ammonia or urea level and treatment conditions (moisture, temperature, duration of treatment etc.). Similar variations were also described (e.g. Castrillo et al., 1995, Orskov et al., 1983, Schneider and Flachowsky, 1990). 3.2. Straw intake and weight gain Ammonia or urea treatment of wheat straw resulted in higher digestibility values (Table 1) and increases straw intake (Table 5). Pair feeding experiments A I and B I allow to quantify the effect of increased digestibility on daily weight gain of bulls. Adequate intake of untreated and treated straw resulted in 69 or 55 g day-’ higher weight gain for ammonia or urea treatment (Table 5). Ad libitum intake of treated straw improved daily weight gain with range of 74 to 290 g (Table 5). The little increased weight gain after ammoniation may be due to the low effect of treatment on straw intake (0.54 kg animal-’ day-‘). Urea treatment increased straw intake between 1.45 and 1.87 kg DM animal-’ day- ’ (Table 5). The higher weight gains of the bulls can be attributed mostly to the increased straw intake and less on the higher digestibility caused by ammonia or urea treatments. In the case of urea treated straw the higher energy gain and the increased weight gain of bulls (Table 5) resulted from: * the higher energy intake from treated straw under pair fed conditions (= 30% of the total higher energy intake) * the increased DM intake of treated straw under ad libitum feeding conditions ( = 53% of the total higher energy intake) * the increased energy supply associated with the increased DM intake of treated straw under ad libitum conditions (= 17% of the total higher energy intake). Our results agree with findings already published (e. g. Castrillo et al., 1995, Fahmy and 0rskov, 1984, Silva et al., 1989). Sundstal (1983/84), compared untreated and ammonia treated straw in six experiments (84-172 days). He reported that ammonia treatment resulted in 86 g lower up to 305 g higher daily weight gains. The lower weight gain and the poor effect of ammoniation on digestibility was most probably due to an inadequate procedure of straw treatment. Some authors have underlined that straw

G. Flachowsky et al./Animal Feed Science Technology 60 11996) 117-130

125

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G. Flachowsky et al./Animal Feed Science Technology 60 (1996) 117-130

roughness (Kemrey and Black, 1984, Orr et al., 1985>, taste or odour of ammoniation (Grovum and Chapman, 1988) may depress straw intake. These factors may be responsible for the high variation in dry matter intake and weight gain in our experiments (Table 5). 3.3. Eficiency

of straw treatment

Animal growth was used for evaluation of straw treatment by various ammonia sources. The factor straw treatment caused increased daily weight gains between 55 and 290 g (Table 5). The lowest responses were measured under pair feeding conditions. This course of calculations disadvantage faster growing bulls because of their higher energy demands for maintenance due to the heavier body weight and the higher fat and energy deposition. Fixed final body weights of animals may be more favourable to compare the efficiency of different straw treatments. A similar situation was discussed already in the course of evaluating feed additives for growing animals (Flachowsky et al., 1994). Nevertheless the higher weight gain was used to calculate the efficiency of treatments. Based on the difference between nitrogen used for straw treatment and the nitrogen added as urea to keep the rations isonitrogeneous the amount of N per kg weight gain or the weight gain per kg N used for treatments was calculated (Table 4). Between 0.14 and 1.3 kg N per kg weight gain increase were necessary. On the other side between 0.8 and 7.0 kg body weight per kg added N were produced from treated straw due to the higher digestibility and the increased straw intake. Ammonia treatment in experiment A I showed the lowest N-efficiency (Table 4). The highest response of urea treatment was measured when wet straw treated with 2.5 and 4% urea per kg DM was fed ad libitum (5.1 and 7.0 kg weight gain per kg N added, Table 4). On the average of the experiments with bulls additional N-intake of 1 kg resulted in increased liveweight gains in the range of 3 kg, when ammonia or urea treated straw was fed. Considering a conversion rate of grain into beef from 5 to 1, cereal yields between 3.8 and 35 kg per kg N are necessary for the same N-efficiency neglecting factors as transport and cover straw with plastics. Various information on the yield of grain as dependent on fertilization intensity are available. 16-20 kg grain and 32-40 kg straw per 1 kg N are produced, when N is given 1978). Grain production value per 1 kg N to an unfertilized field (Anonymous, decreased with higher fertilization levels for example decreasing from 30 to 27, 23, 20, 10 and 3 kg wheat per kg N when N-fertilization increased from 30 to 60, 90, 120, 150 and 180 kg per ha (Fink, 1992). Mean yields varied between 10 and 25 kg gram per kg N given to normal fertilized fields (Fink, 1992). Table 6 shows the potential of beef production as depended on grain conversion into beef and surplus of grain per kg fertilizer N. Straw treatment with ammonia or urea seems to be more favourable (see hatched area of Table 6) with decreasing additional yields of grain per kg fertilizer N and with increasing conversion rates from grain to live-weight gain. Comparing calculations of using of N as fertilizer or as source for straw treatments are very useful under consideration of different cereal yields and various cereal: beef conversion ratios. Additional straw yields and forage yields depending on fertilizing should also be taken into account.

G. Flachowsky et al./Animal Table 6 Effect of 1 kg N as fertilizer (as ammonia beef conversion

Feed Science Technology 60 (1996) 117-130

or urea) on grain yield and beef production

Additional

Grain conversion (kg grain per kg weight gain)

depending

127

on grain

:

grain yield (kg) per kg N 30

40

7.5 :

4: 1 5: 1 6: 1 711

10 8 6.7 5.7

4.2

3.4. Energetical and ecological aspects In the energetical and ecological calculations only energy required for ammonia or urea synthesis has been used. 60 or 80 MJ of fossil energy are needed (Cervinka, 1980, Reinhardt, 1993) to fix 1 kg N as ammonia or urea. Under consideration of higher daily weight gains of bulls fed with ammonia or urea treated straw (Table 5) fossil energy in the range of 11 to 79 MJ is needed per kg live weight gain (Table 7). Animal protein as human food is one of main aims of animal production. From the energetical point of view beef cattle require fossil energy in the range of 360 to 600 MJ to produce 1 kg of protein, or in other terms the costs for 1 MJ protein gain amount to 15-25 MJ fossil energy (Flachowsky, 1992, Pimentel, 1992). Unfortunately intensive beef production is more energy expensive as compared to other forms of protein production by domestic animals (Krummel and Dritschilo, 1970, Pimentel et al., 1980). One kg body weight of bulls contains about 150 g protein (see Table 5) or 80 g edible protein. Considering this quantity fossil energy in the range of 75-528 MJ is required for 1 kg protein gain by straw treatment with ammonia sources (Table 7). This amount is comparable with energy costs in intensive beef production systems. CO, and N outputs shown in Table 7 are considered as pollution problems associated with NH,-treatment of straw. Low animal response (see Table 5) resulted in high fossil energy amounts and high CO, and N outputs per animal performance (Table 7).

Table 7 Fossil energetic

costs and environmental

Exp. No.

Comparison of groups

AI

1:2 1:3 1:2 I:2 1:2 I:2 1:3

A 11 BI B II B III

burdens feeding NH, /urea

Energy costs for N-fixing MJ fuel kgweight gain increase 78.0 79.2 27.2 52.8 16.0 11.2 26.4

’

MJ fuel kgprotein gain increase 520 528 181 352 107 75 176

treated straw

Environmental

’

burdens

CO,-output associated with N fixing (g kg- ’ weight gain increase)

N-output (g N losses from straw per kg weight gain increase1

5070 5150 1330 3430 1040 730 1720

1296 1370 405 660 195 148 330

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G. Flachowsky er al./Animal Feed Science Technology 60 (19%) 117-130

Moreover, additional experiments are necessary to control these calculations and to evaluate the various treatments of straw.

4. Conclusion Ammonia or urea treatments of straw increase the digestibility, improve straw intake and the growth rate of bulls as compared to untreated straw feeding. The input of one kg N for straw treatment effects increased body weights between 0.76 and 7.0 kg averaging 3 kg. In the case of lower response N-fertilizing of grain or forage and feeding to beef cattle or other animals seems to be more efficient as compared to treatment of straw with N sources. Ammoniation of straw by ammonia and urea seems to be justifiable only, when . a high portion of N (more than 40%) is fixed in the straw and available for ruminants digestibility and intake of the straw are considerably increased - more than 4 kg weight gain per kg added N were achieved (comparable with 20 kg grain per kg N and a cereal : beef conversion ratio of 5 to 1). More long term dose-response feeding experiments with ammonia or urea treated straws are necessary as a precondition for an improved nutritional, energetical and ecological evaluation of the treatments. ??

Acknowledgements The authors wish to tank Gisela Sallen and Dr. H. BShme for their assistance in preparing the paper.

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G. Flachowsky et al./Animal Feed Science Technology 60 (1996) 117-130 Eldelsten,

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