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Molasses energy blocks for beef cattle

C.W. Mwendia and M. Khasatsili
National Agricultural Research Station, Kitale,
P. O. Box 450
Kitale, Kenya


Abstract
Introduction
Materials and methods
Results
Discussion
Conclusion
Acknowledgements
References


Abstract

The present trial was to investigate the possibilities of the farmer making his own concentrated energy blocks from the locally available ingredients and to determine at what cost he does so. The suitability and acceptability of the blocks by steers were also studied. 16 unreplicated blocks were made using molasses, urea, salt, cement, corncob meal and wheat bran in 24 factorial experiment. Block hardness was found to vary with block type, location, technique of manufacture and to some extent with temperature and humidity although there was no evidence that the blocks hardened any more beyond day nine. In a 15-minute intake observation, average consumption per 'visit' of molasses blocks containing wheat bran was 142 g which differed significantly (P<0.05) from the average consumption of 96 g for those containing corncob meal. Consumption of blocks containing wheat bran was not affected (P<0.05) by method of preparation, proportion of molasses or even the location of the blocks. Consumption of corncob blocks containing 50% molasses was 131 g which differed (P<0.01) from 68 for those containing 45% molasses. Placement of blocks containing corncob meal in the sun resulted into average consumption of 116 g, an amount different (P<0.05) from 77 g for those placed in the shade. In all cases, the cost of the blocks was between 20 and 25% the cost of Crystalyx, a standard commercial preparation.

Introduction

In beef cattle nutrition, energy among others can be limiting especially in the dry season leading to slow livestock development or indeed a reversal in livestock gains. In Kenya, beef cattle numbers are estimated at some 9.5 million (ISNAR, 1985) and occupy large tracts of land in the principally 79% of Kenyan rangeland. Beef cattle numbers given for 1983 through to 1985 (Owiro, 1985) would indicate that 11.5% of the animals were lost in the 1984 drought. Similar or worse losses have been reported in the Sahel region of West Africa (Bourn et al, 1987) and in Wollo, Shoa and Hararge provinces of Ethiopia (ILCA, 1986).

Pickstock (1985) has reported that in times of drought when the energy and protein reserves of animals fall to dangerously low levels, molasses - urea mixtures can be fed in amounts of up to 2 kg a day thereby helping to satisfy both energy and protein needs for maintenance. The use of liquid molasses and urea have had their problems (ILCA, 1986; Sansoucy, 1986). According to Sansoucy (1986) these problems are easily solved through use of molasses urea blocks whose advantages are in the handling, storage, transportation and even in the actual feeding. The concept of energy blocks is not new and there are over 70 formulae adopted by various countries depending on the locally available ingredients. (Sansoucy, 1986).

Though the technology involved in block-making is both simple and practicable, such factors as ingredients used, mixing technique and environmental factors affect the block stability. The state of hardening is of particular interest from the point of view of transportation and consumption by the animals. It was for this reason that an investigation was carried out to study the technique of making energy blocks using the commonly available ingredients and to study the economics involved in addition to determining how acceptable the blocks are to the beef cattle.

Materials and methods


Block quality
Block stability
Block consumption by beef cattle


The methodology of making molasses blocks was based almost exclusively on the work of Sansoucy (1986). In a second set of blocks, corncob meal replaced wheat bran as suggested by Shenkute Tessema (personal communication). Sixteen unreplicated blocks were made each weighing approximately 6.5 kg. The trial was on a factorial layout with two different levels of molasses, (50% and 45%), two residues (wheat bran and corncob meal), two storage systems (in the sun and under shade). Table 1 shows the composition of the blocks.

Table 1. Composition of molasses blocks.


Wheat bran

Corncob meal

Block type

I

II

III

IV


%

Molasses

45

50

45

50

Urea

10

10

10

10

Salt

5

5

5

5

Cement

15

10

15

10

Wheat bran

25

25

n.a

n.a

Corncob meal

n.a

n.a

25

25

n.a. = not available

Mixing of the ingredients was carried out in a strict order starting with molasses followed by urea, salt, cement and ending with wheat bran or corncob meal. It was particularly suggested by Sancoucy (1986) that the hardening process is improved by mixing the cement with water first as the water contained in the molasses was considered insufficient to wet the cement. To investigate this, the cement was mixed with extra water (37 parts to 100 parts cement w:w) before further mixing with the other ingredients. It was also considered necessary to investigate the stability of the blocks when placed in the open and under shade to simulate the two conditions likely to prevail under real world farming. conditions. The factors investigated were block quality, stability and block consumption by beef cattle.

Block quality

Nutrient content of the blocks was determined by proximate analysis for dry matter, crude protein, ether extract, gross energy and minerals such as calcium, phosphorus, magnesium, sodium and potassium using the accepted analytical standards (AOAC, 1975). The fibre tractions were analysed according to the procedures of Goering and van Soest (1970).

Block stability

Hardness of the blocks was used as an indicator of block stability. To determine hardness, a penetrometer, one of the Chatillon precision instruments (Chatillon - N.Y.-USA. GAUGE R. - CATL 719-20) was used. For every block there was determination of the relative force needed to sink the penetrometer to a preset depth. At any one time, four such determinations were made on a block at 9.00, 12.00, 15.00 and 18.00 hours. The process was continued daily for 12 days from 9/3/87 (day 5) to 20/3/87 (day 16). Data for days 5, 6, 10, 11 and 12 were excluded from analysis due to missing values. An analysis of variance on block hardness under various conditions was carried according to Steel and Torrie (1980).

Block consumption by beef cattle

Block acceptance and consumption by beef cattle was determined in a 15 minute observation. All the 16 blocks were weighed and placed in boxes arranged in a wide semi circle. Eight observers were assigned to watch over two blocks each. A herd of grazing hereford steers was then released to sample the blocks. The observers had to record the number of 'visits' by steers to all blocks as identified in Figure 1. After 15 minutes, block left overs were weighed and relative consumption calculated on 'per visit' basis. Major comparisons were carried out by paired 't' test (Snedecor and Gochran, 1967).

Results


Block quality
Block hardness
Block consumption by beef cattle
Block costings


Block quality

The chemical composition of the blocks and their ingredients is given in Table 2. The standard "Grystalyx" had higher dry matter than the other blocks and contained no fibre. The Ca:P ratio of "Crystalyx" is close to 2:1 whereas for the other blocks it ranged from 11:1 for block type II to nearly 26:1 for block type III. Except for calcium and crude protein, the crystalyx block contained higher quantities of other chemical components than the rest of the blocks.

Table 2. Chemical composition of the blocks and their ingredients.

* Gaps indicate analyses that were never carried out.

Figure 1. Relative block hardness with changes in temperature and relative humidity.

Block hardness

Block hardness varied significantly (P<0.001) both within the day and also between the days (Figure 2). For those blocks kept in the shade, correlation coefficients of pressure with temperature and relative humidity were +0.55 ad -0.66 respectively. Although none of the correlation coefficients were found significant (P>0,05) there is a trend that would indicate that these two environmental factors had an effect on block hardness especially those in the shade. There was no evidence that the blocks hardened any more beyond day nine.

At a relative penetration pressure of 4.71, the blocks kept in the open were significantly harder (P<0.001) than those in the shade which recorded a mean pressure of 4.56 (Table 3).

By use of 't' test on figures in Table 3, it was shown that the mean pressure for wheat bran blocks was 5.39 which was significantly different (P<0.01) from the mean pressure of 3.87 for corncob blocks. There were significant (P<0.001) interactions demonstrated between treatments and sites. These interactions were shown among the corncob meal blocks K, L, O and P prepared without addition of water which unlike the others hardened more in the shade than in the open. At a mean relative pressure of 4.98, blocks with water added at mixing were significantly harder (P<0.001) than those without added water whose pressure was 4.28. 45% molasses blocks were harder (P<0.001) at a pressure of 5.13 than 50% molasses blocks at a pressure of 4.14.

Table 3. Relative block pressure

Sun

Shade

Mean

Block

Pressure

Block

Pressure


A

5.89

B

5.76

5.83a

C

5.93

D

5.91

5.92a

E

5.68

F

4.71

5.20b

G

5.05

H

4.22

4.64c

I

5.23

J

5.15

5.19b

K

2.75

L

4.40

3.58e

M

4.54

N

3.44

3.99d

O

2.57

P

2.87

2.72f

Mean

4.71q


4.56r


Subscripts a,b,c,d,e,f, different at P<0.001
Subscripts q,r different at P<0.001

Block consumption by beef cattle

Consumption of blocks is shown in Table 4 followed by comparisons of interest in Table 5. No differences were evident in the consumption of wheat bran blocks irrespective of composition, location or method of preparation. For the corncob blocks, placement in the sun resulted into significantly higher consumption (P<0.01) and so did inclusion of molasses at 50% level compared to 45%. Overall, the consumption of wheat bran blocks was higher (P<0.05) than for corncob blocks.

Table 4. Block consumption by yearling steers

Block

Total Consumption (kg)

Number of "visits"

Consumption per "visit" (g)

A

5.20

31

168

B

3.70

37

100

C

5.30

35

151

D

2.80

65

43

E

5.80

52

112

F

4.65

51

91

G

5.60

26

215

H

5.10

20

255

I

2.00

23

87

J

1.20

35

34

K

4.75

58

82

L

2.10

48

44

M

2.70

21

129

N

1.80

18

100

O

5.90

36

164

P

9.20

40

130

Block costings

The cost of making the energy blocks was compared with the current cost of other preparations appearing in the market (Table 6). Some of these preparations are not in block form and for that reason "Crystalyx" which is a trully commercial energy block was used as the standard. It is evident that under current prices block type I to IV cost between 20 and 25 percent the cost of crystalyx while the other commercial supplements, that is, molasses-urea mixture (MUM) and molafeed cost between 25 and 30 percent.

Table 5. Comparisons on block consumption

 

Wheat bran

Corncob meal

Variable

Mean

Mean difference

T-value

Mean

Mean difference

T-value

Location

Sun

162



116





40

1.23NS


39

7.44**

Shade

122



77



Molasses

50%

168



131





52

0.90NS


63

6.91**

45%

116



68



Water without


166



105




40


0.94NS


17

1.89NS

with


118










88



Wheat bran


142








46

2.57*




Corncob meal


96






NS = Non significant (P>0.05)
* = Significant (P<0.05)
** = Significant (P<0.01)

Table 6. Comparative cost of blocks and other supplements

Block type

Unit cost of/kg*

Cost of 100 kg

As % of Crystalyx block


Kshs

US $ Equivalent

block (US $)


I

1.630

-

8.89

24.3

II

1.588

0.087

8.75

23.6

III

1.352

0.075

7.45

20.2

IV

1.310

0.072

7.21

19.5

MUM

1.800

9.91

9.91

26.8

Molafeed

2.000

0.110

11.01

29.7

Crystalyx

6.720

0.370

37.01

100.0

* Assumptions
1 US $ = KShs. 18.158 as on Nov. 12, 1988


Unit cost (KShs/kg)

Wheat bran

1.61

Salt

3.70

Molasses

0.76

Urea

4.60

Cement

1.60

Corncob meal

0.50

Discussion

It has been demonstrated in this trial that it is possible to make molasses urea blocks using the commonly available ingredients. Both the dry matter and crude protein levels of the blocks compare very closely to those of the "Crystalyx" blocks (Table 2). One very big differences is that "Crystalyx" contains no fibre components whereas other block types notably III and IV contain more than 20% neutral detergent fibre. This could perhaps explain the relatively higher gross energy determined for the "Crystalyx" block. Wheat bran and corncob meal were the main contributors to the fibre fractions for block types I to IV (Tables 1 and 2).

Hardening and general stability is a crucial aspect of the blocks. According to Sansoucy (1986) too hard a block would result in inadequate intakes while too soft a block induce overconsumption with the possible consequences of urea toxicity. Those blocks containing wheat bran (blocks A through to H) demonstrated better compactness (Table 3) unlike the other blocks containing corncob meal which were inconsistently soft. The ideal block pressure is unknown and "Crystalyx" used as a standard here was so hard that the penetrometer could not penetrate it at all thereby raising doubts as to whether 250 kg animals could consume an average of 700 g per day considered ideal for maintenance (Sansoucy, 1986). Prior mixing of cement with additional water resulted into harder blocks in agreement with the suggestion of Sansoucy. Many factors may have contributed to the general softening of the blocks especially among those made out of corncob. Temperature and humidity are some of the suggested possibilities. Use of quicklime instead of cement is said to give harder blocks and so does the use of molasses with Brix degree (related to dry matter) equal to or more than 85 as suggested by Sansoucy. The dry matter of the molasses used here was 72% (Table 2). From the feed analysis tables NRC, (1978) cane molasses with a dry matter of 75% has a Brix degree of approximately 79.5.

It, therefore, follows that the molasses used in this trial had a Brix degree of approximately 76, a figure that is well below preference. The fact that 45% molasses blocks were harder than those containing 50% molasses indicates that the higher levels of cement in the latter blocks was an overiding factor in the determination of block hardness.

Consumption of the blocks by yearling steers indicated that the highest intakes were among the better compacted wheat bran blocks (Table 5). In a real performance trial this may not necessarily be a good thing. In a 15-minute period an average of 142 g of wheat bran blocks had been consumed. In a whole day this could probably result into dangerously high levels while corncob blocks containing 45% molasses, may on the other hand not provide enough energy and protein for optimum utilisation of crop residues. By manufacturing his own energy blocks using ingredients that are available at fairly controlled government prices the farmer would benefit from a saving of more than 75% the cost of company manufactured blocks. The practicability of utilisation of energy blocks at farm level is no longer in question (Preston and Leng, 1987) and an improvement in livestock performance is guaranteed (Sudana and Leng, 1987; Sansoucy et al, 1986). For Kitale, Kenya, conditions there is a realised need to investigate the performance of steers given a selected number of blocks. This is the next step of investigation especially in the relatively drier months of December and February.

Conclusion

The technology of making energy blocks for dry season feeding is both simple and practicable. However, getting the right kind of block is dependent on may things among them being environmental factors, ingredients used and manufacture technique. Although molasses-urea blocks containing wheat bran were shown to be more stable and were consumed at higher levels than those containing corncob meal, complexity in real-life utilisation of the blocks as a whole needs further investigation. The economic saving is considerable over purchased commercial blocks although the real benefit may turn out to be the improved livestock performance since the farmer can alter block composition to suit his needs.

Acknowledgements

The authors wish to register their appreciation for the laboratory analyses done by technologists S.K. Waweru and R. Millo. Mr. Roger Kamidi assisted greatly with the statistical analysis and interpretation of results for which we are bully thankful. Kitale Research Centre Director, Mr. D.K. Muthoka is thanked for creating the atmosphere that made the execution of this trial possible. This paper has been prepared for publication with the kind permission of the Director, Kenya Agricultural Research Institute, Nairobi.

References

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Bourn, D., Denda, I., Ridder, N., Wagenaar, K. and Wing, W. 1987. Where have all the Livestock gone? ILCA Newsletter 6:(1):3-4.

Goering, H.K. and Van Soest, P.J. 1970. Forage fibre analysis. ARS of US Dept. of Agriculture. pp. 1-12.

ILCA, (International Livestock Centre for Africa) 1986. Emergency cattle feeding. In: SPORE No.2 of 1986 CTA Bimonthly bulletin of Technical Centre for Agricultural and Rural Cooperation for disseminating of Scientific and Technical Information, Wegeningen, The Netherlands, pp 7.

ISNAR (International Service for National Agricultural Research), 1985. Kenya agricultural research strategy and plan. ISNAR 24(2):122.

NRC, (National Research Council), 1978. Nutrient requirements of dairy cattle. No. 3. National Academy of Science, Washington DC. 44, pp.

Owiro, Z. 1985. Ministry of Livestock Development Annual Report. p. 27.

Pickstock, M. 1985. Molasses as drought feed for livestock. Agric. Science Digest. M.F. Massey Ferguson 8:(3):3.

Preston, T.R. and Leng, R.A. 1987. Matching ruminant production systems with available resources in the tropics and sub tropics. Penambul Books, Armidale, Australia. pp 192-196.

Sansoucy, R. 1986. Manufacture of molasses - urea blocks. World Animal Review 57:40-48.

Sansoucy, Aarts, G. and preston, T.R. 1986. Sugarcane as a feed. proceedings of an FAO Expert Consultation held in Sato Domingo, Dominion Republic from 7 to 11 July 1986. pp 263-279.

Snedecor, G.W. and Cochran, W.G. 1967. Statistical methods. 6th ed. Iowa State University Press, Ames, IOWA-USA.

Steele, R.G.D. and Torris, J.H. 1980. Principles and procedures of statistics. 2nd ed, McGraw-Hill Book Co., New York, U.S.A. 390. pp.

Sudana, I.D. and Leng, R.A. 1987. Effects of supplementing a wheat straw diet with urea or a urea-molasses block and/or cottonseed meal on intake and liveweight changes of lambs. ARNAB (ILCA) Newsletter 7:(3):22-23.


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