Urea blocks. II. Performance of cattle and sheep offered urea blocks in Syria

Urea blocks. II. Performance of cattle and sheep offered urea blocks in Syria

M Hadjipanayiotou*, L Verhaeghe**, A R Kronfoleh, L M Labban, M Amin, M Al-Wadi, A Badran, K Dawa, A Shurbaji, M Houssein, G Malki, T Naigm, A R Merawi and A Kader Harres

Animal Production Research Division, Ministry of Agriculture and Agrarian Reform, Damascus, Syria

(Present address: *Agricultural Research Institute, Nicosia, Cyprus; **FAO, Animal Production and Health Division, Via delle Terme di Caracalla, 00100 Rome, Italy

Six demonstration trials, one with dry Shami cows and five with Awassi sheep were carried out to compare the performance of animals fed poor quality roughages with or without urea-blocks (UB). Feeding UB did not increase intake of straw in cows or sheep. Cows with UB gained weight (265 g/day) and those without lost weight (-265 g/d). Sheep with UB performed better that those without them. In the trials with sheep grazing cereal stubbles, the animals were in positive energy balance in only one trial. Response to UB was greater when the basic diet was composed of only poor quality roughages, improving the efficiency of feed utilization. It is concluded that UB composed of urea, salt, poultry excreta, olive cake, wheat bran and other agro-industrial by-products can be widely used for upgrading the nutritional value for ruminants of poor quality roughages available in most developing countries.

KEY WORDS: Multi-nutritional blocks, urea, molasses, cattle, sheep, fibrous crop residues, agro-industrial byproducts.

Cereal straw and other poor quality roughages are the main component of the diet for ruminants in the Syrian Arab Republic and in many other developing countries during most of the year. Their low nitrogen content reduces both digestibility and intake.

The effect of supplementing straw with nitrogen and various energy sources has been studied by many researchers (Andrews et al 1972; Hadjipanayiotou et al 1975; Preston and Leng 1984; Capper et al 1989). It has been found that, while small amounts of supplements may stimulate rumen function, digestion and intake of straw, high levels of supplements may lead to a depression of microbial activity reducing rumen digestibility and intake.

Molasses-urea blocks (MUB) provide nutrients to the rumen microbes and to the animal in small amounts throughout the day (Preston and Leng 1987). This is an important feature when animals are on high- fibre, low-nitrogen cereal straws, since the nutrients in the block are available while the basal diet is being fermented. Apart from providing non-protein nitrogen, the block can also be a source of rumen bypass protein, macro and micro-minerals, vitamins, pharmaceuticals and additives to manipulate rumen fermentation. Blocks can be manufactured with a wide variety of by-products, promoting therefore their utilization in different localities. Easy transportation is another advantage of blocks.

The purpose of this work was to study the performance of cattle and sheep fed poor quality roughages with or without a urea-containing block (UB).

Six demonstration trials, one with cattle and five with sheep, were carried out. The animals were weighed at the beginning and at the end of each trial. The duration of each trial is shown in the tables containing the results of animal performance.

Blocks were made in a 300 litre concrete mixer following the procedure outlined by Hadjipanayiotou et al (1993).

The cattle trial was carried out at Deir El Hajjar State Shami cattle research station near Damascus. Twelve mature non-pregnant dry Shami cows were divided in two groups of six, and randomly allocated to a control or to a UB treatment. All animals were offered daily 2 kg of cottonseed hulls per head and wheat straw ad libitum. Animals on the UB treatment had free access to the block at all times. The UB was composed of urea 8%, salt 10%, cement 15%, poultry litter 20%, wheat bran 25% and dried olive cake 22%. Animals were housed in individual pens and had free access to water. Feed offered was routinely sampled and analysed. The UB was also analysed. The chemical composition of the feedstuffs is presented in Table 1.

Table 1: Chemical composition of feedstuffs (% in DM)

	Straw	Cottonseed hulls	Block

Dry matter	93.1	92	93.4
Ash	8.2	2.9	19.0
Crude protein	3.0	4.9	23.9
Crude fibre	39.2	53.0	15.4

Studies with sheep were carried out at the research stations of Hama (centre of the country) and of Kamishly (North East) and on- farm-tests at private farms in Salamieh (near Hana) and in Sweida (South West).

In two trials at research state farms, animals were housed indoors in groups and fed chopped straw ad libitum. In the Kamishly study, 32 ewe lambs 10-11 months old were also given a supplement of 250 g of whole barley grain. In the study at the Hama research station 70 Awassi male lambs of about 45 kg were utilized. At both places sheep were divided in two similar groups, one receiving UB. All groups were given the equivalent of 15 g per head per day of a mineral-vitamin mixture composed of 8% NaCl, 8% Na₂SO₄, 8% wheat bran, 54% Ca₂PO₄, 20% limestone and 2% vitamin and trace element mixture.

In the other demonstration trial carried out at the Kamishly state research centre, Awassi sheep (ewes and ewe lambs) were divided in two groups and randomly allocated to the two treatments, with and without UB. All animals grazed together on cereal stubbles and those on the UB treatment had free access to block for about 12 h daily.

For the on-farm trial in Salamieh, 200 mature Awassi ewes, selected from a flock of 500 sheep, were divided in two groups based on their liveweight and randomly allocated to two treatments, with and without UB. Sheep with UB were kept in a separate flock and had access to UB for about 12 h per day. Both groups grazed cereal stubbles in adjacent fields of similar capacity.

For the Sweida study, sheep belonging to two farmers had access to UB at their overnight corrals. Sheep from another two farmers served as a control with no UB. All animals grazed together on cereal stubbles for about 10-14 h daily, and at the end of the day each group returned to its corral. No other supplement was given to the sheep except water.

The UB used in all trials with sheep were made at least one month before being offered to the animals. The block was composed of 10% urea, 10% NaCl, 8% cement, 7% Ca(OH)₂, 21% dried poultry manure, 24% wheat bran and 20% molasses.

Data were analysed by one way analysis of variance. For final weight, the initial weight was used as covariate.

With the exception of one cow in the UB group, all the others remained healthy throughout the experimental period. The data from this animal were not included in the analysis since the illness was not related with block feeding. The intake of straw was not different for the two groups but animals with UB gained weight, while those without UB lost weight (Table 2).

Table 2. Effect of urea-block feeding on the performance of dry, non-pregnant Shami cows (Test period: 7/8-11/11/90)

	No Block	Block	SD	Prob

No. of animals	6	5
Feed intake (g 100 kg LW/day)
Straw	800	800	100	NS
Cottonseed hulls	400	400
Urea-block		198
Weight gain (g/day)	-265	265	424	<0.05

Table 3. Effect of urea-block feeding on the performance of Awassi ewe-lambs offered chopped cereal straw ad libitum, Hama research centre (Test period: 22/12/90-21/2/91)

	No Block	Block	SD	Prob

No. of animals	35	35
Liveweight (kg)
Initial	40.1	40.7	5.3	NS
Final	34.9	37.5	2.0	<0.01
Loss (g/day)	88	53	3.9	<0.01
Feed intake (g/100 kg LWt/day)
Straw	2000	2000
Block	-	230

Table 4. Effect of urea blocks on the performance of Awassi sheep offered chopped cereal straw ad libitum, Kamishly research centre (Test period: 3/12/90-31/1/91).

	No Block	Block	SD	Prob

No. of animals	16	16
Liveweight (kg)
Initial	39.8	39.8	3.8
Final	42.1	43.6	2.4	<0.08
Weight gain (g/day)	41	67	4.2	<0.08
Feed intake (g/100 kg LWt/day)
Barley grain	600	600
Straw	1700	1700
Block		292

The consumption of block (g/100 kg liveweight) was 202 for Shami cows (Table 2), 230 for sheep at Hama research center (Table 3), 292 for sheep at Kamishly, study I (Table 4), 112 for sheep at Kamishly, study II (Table 5), 220 for sheep at Salamieh (Table 6) and 127 for sheep at Sweida (Table 7).

Table 5. Performance of Awassi Sheep grazing stubbles (29/9-24/10/90) without (control) or with blocks, at Kamishly researh station

	No Block	Block	SD	Prob

No. of animals	86	83
Weight loss (g/day)	56	6	7.17	<0.05
Block intake (g/100kg LW/day)		112

Table 6. The effect of urea-block feeding on the performance of Awassi sheep grazing cereal stubbles in the Salamieh area, Hama (Test period 12/9-24/10/91)

	No Block	Block	SD	Prob

No. of animals	99	100
Live weight (kg)
Initial	45.8	44.8	5.5	NS
Final	41.5	43.0	1.7	<0.01
Loss (g/day)	101	41	4.43	<0.01
Block intake (g/100kg LW/day)		222

Table 7. The effect of urea-block feeding on the performance of Awassi sheep grazing cereal stubbles in the Sweida area (Test period: 12/7-12/9/91)

	No Block	Block	SD	Prob

No. of animals	71	63
Live weight (kg)
Initial	42.8	44.7	7.3	NS
Final	44.6	49.9	2.9	<0.08
Loss (g/day)	30	86	5.08	<0.01
Block intake (g/100kg LW/day)		127

Sheep with UB performed better than those on the control diet (Tables 3-7). Group intake of UB was recorded in all trials. The group intake of straw was recorded in the trials carried out at the research stations (Tables 3 and 4). There were significant differences (P<0.05) in animal weight changes favoring those that received UB in all trials, except in the second study at Kamishly where there was only a strong trend (P<0.08) towards better performance in the animals that received UB (Table 5). Sheep only gained weight in the trials at Sweida (Table 7) and at Kamishly (Table 4), in the others they lost weight (Table 3, 5 and 6).

Feeding UB usually increases the intake of the basal diet as reported by Sansoucy et al (1988). These workers stated that the straw consumption with MUB is usually about 25-30 % higher, but only 5-10% higher when some concentrates are also given. Similarly, Kunju (1986) reported an increase in intake of straw from 4.4 to 5.7 kg/day, when 1 kg concentrates were replaced with 560 g block. Another experiment was reported in which the intake of straw was only marginally increased from 6.4 to 6.8 kg per day, when the block was added to a ration including 1 kg/day concentrates. In contrast, our findings showed no difference in straw intake between the control and block groups, and are in line with the report of Neric et al (1985).

During the initial period in the cow test (first 33 days), the consumption of straw in the two treatments was similar (UB 4.5 vs Control 4.3 kg/head/d). In the second interval (34-74 day on test), animals on both treatments suffered a decrease in straw intake (UB 3.45 vs Control 3.25 kg/head/day) whereas in the last part of the trial (75-96 day on test) cows on UB maintained their straw intake and those on the control diet suffered a further reduction (UB 3.45 vs Control 2.9 kg/head/day). Intake of straw, when offered alone, decreased with time and produced severe weight losses in studies with sheep (Hadjipanayiotou et al 1975).

Sansoucy et al (1988) reported that the intake of block varied with the type of animal (eg: lambs 400; calves 250; Jersey bulls 150-185 and Zebu heifers 110 g/100 kg of body weight). In the present studies, relative higher intakes of block were observed for Awassi sheep compared with Shami cows, when both blocks and straw were offered ad libitum (202 for cows vs 230 and 293 for sheep). Differences in block intake in the trials with sheep might be due to the period of time the animals had access to blocks. This was the case in the trials with sheep in Sweida and Kamishly (study II). On the other hand, the high block intake -- despite limited time access to block in the Salamieh trial -- could be due to the poor availability of cereal stubbles for grazing in this study. In none of the experiments, have sheep eaten the quantities of block (400 g/100 kg liveweight/day) reported by Sansoucy et al (1988). This might be partly due to the hardness of the blocks. The block composition (only 20% of molasses) and the nature of the basic diet might be other reasons for the lower intake.

Pearce (1973) found no increase in hay intake as a result of MUB supplementation, although liveweight gain increased. Furthermore, in accord with our data, effects on liveweight gain were more pronounced than effects on feed intake as in the work of Kunju (1986). The increase in weight gain observed in our study and that obtained by Leng (1984), despite marginal increase in straw intake, suggest that access to the block results in a marked increase in the efficiency of utilization of nutrients by the animal.

It is concluded that UB can improve the efficiency of utilization of poor quality roughages and results in improved animal performance that otherwise could only be obtained by using greater quantities of conventional energy and protein supplements.

The authors are grateful to the FAO and UNDP offices in Damascus, to Drs S Badawi (Chief AGON FAO Rome) and R Sansoucy (Senior Officer, Feed Resources, AGAP FAO Rome) and K Qamar (CPO, AGON, FAO Rome) for continuous support and encouragement and to his Excellency the Minister of Agriculture and Agrarian Reform and his staff for making available all necessary facilities for the implementation of this work. The studies were carried out in conjuction with the "Greater and Improved Use of Agricultural Residues for Animal Feeding Project", a joint undertaking between the Government of Syria and the UNDP and FAO.

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