Livestock Research for Rural Development 21 (5) 2009 Guide for preparation of papers LRRD News

Citation of this paper

On-farm evaluation of lactating crossbred (Bos taurus x Bos indicus) dairy cows fed a basal diet of urea treated teff (Eragrostis tef) straw supplemented with escape protein source during the dry season in crop-livestock production system of north Shoa, Ethiopia

Mesfin Dejene, Seyoum Bediye*, Aemiro Kehaliw, Getu Kitaw and Kedir Nesha

Ethiopian Institute of Agricultural Research (EIAR), Holetta Research Center, P.O.Box 2003, Addis Ababa, Ethiopia
*Ethiopian Institute of Agricultural Research, P.O.Box 2003 Addis Ababa, Ethiopia
mesfindegene@yahoo.co.uk

Abstract

An on-farm study was conducted with crossbred lactating dairy cows, maintained under market oriented mixed farming system at Kuyu district, in north Shoa zone, Ethiopia to assess the effect of feeding intervention diet (4% urea treated teff straw (4kg of urea, 90 liters of water and 10 kg of molasses per 100 kg of teff straw ensiled for 3 weeks) supplemented with a concentrate mixture (linseed cake 48% as source of escape protein; wheat bran 50% and salt 2%)). The assessment was done on chemical composition, IVOMD, feed intake, milk yield, body weight, body condition, profitability and farmers opinion during the dry season. A total of 15 households having two lactating cows per house hold were selected. 30 cows in early to mid lactation with an average body weight of 286.855.05 kg were selected and balanced for their parity, stage of lactation, level of milk yield and body condition and divided in to two groups (15 cows per group). 15 cows were fed urea-treated teff straw ad lib as a basal diet supplemented with a concentrate mixture @ 0.35 kg /kg of milk yield/cow/day (T1), and the other 15 cows of one group were maintained as usually practiced by farmers (control) (T2).  

Urea treatment of teff straw  increased the CP content from 4.3 to 8.9 % (increased by 107%) and IVOMD by 7.9 %, reduced the NDF and hemicellulose contents of teff straw by 6.04% and 26.69% respectively while the ADF, lignin and cellulose contents increased by 8.76%, 23.08% and 6.23%. Feeding urea treated teff straw supplemented with linseed cake based concentrate mixture significantly (P<0.01) increased feed intake, milk yield, live weight gain and body condition score of the cows. Due to the improvement in daily milk yield by 3.48 kg (7.14 vs. 3.66 kg) coupled with a 1.35 % cost reduction/ kg of milk produced, the net profit increased from ETB 4.73/cow/day in the control group to ETB 9.39/cow/day in T1 group. This study demonstrated that the intervention diet increased the net profit for farmers to ETB 4.66/cow/day. According to the opinion of participant farmers, the intervention diet improved roughage intake, milk yield and body condition of the cows during the dry season.  

Feeding urea treated teff straw with bypass protein source was found to be an effective approach to maximize the utilization of locally available feed resources for better animal productivity during the dry season in mixed farming system of Ethiopia.

Key words: Atella, bypass protein, economic analysis, hay, milk yield, noug cake, oat grain, straw treatment, wheat bran


Introduction

Ethiopia is known for large livestock population of which 80% are raised in the highlands where intensive crop farming is also undertaken using ox traction which makes Ethiopia as a unique agricultural feature in addition to the use of teff (Eragrostis tef) grain as a cereal staple food crop. The straw from this crop is widely used as a basal diet for ruminants. Unlike Kenya, the large cattle population of Ethiopia has relatively limited numbers of exotic dairy cattle and their crosses. Less than 1% of the 44.3 million cattle populations of Ethiopia are exotic or crossbred dairy cows (Ahmed et al 2003; CSA 2004). The policy of the government of Ethiopia is market oriented research for development in order to realize food security at house holds level. Access to rapidly expanding urban markets in milk and other dairy products provide farmers with opportunities to identify their production by taking advantage of new technologies and services (Tangka et al 2002). The north shoa zone in general and  Kuyu district in particular appear to have benefited from the distribution of crossbred heifers (dairy stock distribution), co-operatives development, strengthening of AI service at field level and milk marketing and processing with the objective to increase sustainable stallholder dairy production in the highlands of Ethiopia (Ahmed et al 2003). However, most of these projects failed to address the genetic improvement and the feed shortage problem simultaneously. The energy deficit resulting from poor quality or low quantity feed, especially during the dry season, could result in losses in body weight and body condition, thus affecting the production and reproduction efficiency of the cows (Zerbini et al 1998).

 

Apart from the direct benefit to a farm household, dairying has several other attributes to the whole farming system in the area. Despite its importance the productivity and economic contribution of the sector is challenged with various constraints among which nutritional constraints are often the overriding ones. Fibrous crop residues and grazing are the typical diet resources for ruminant animals in the area and often are the only feed resources in extended dry seasons. Low quality roughage which forms the basal feed in Sub- Saharan Africa (SSA) are deficient in nitrogen, energy, vitamins and minerals (Egan 1986; Kabaiji and Little 1988), of which fermentable nitrogen is usually the first limiting. These nutrient deficiencies affect microbial growth and fermentation in the rumen and result in low voluntary intake and organic matter digestibility is also usually below 50%. Teff straw is one of the major crop residues available in the district. Its nutritive value is better than other available crop residues like barley and wheat. However, like many tropical forages, teff straw is also very fibrous and degrades slowly (700g/kg) (Osuji 1994) compared with leaves from trees (Bonsi et al 1995). Since feeding of these low protein roughages hardly support the maintenance requirement and leading to low production and reproduction of the ruminant livestock, various options to alleviate these constraints have been carried out both locally and globally among which up-grading them through treatment with urea and supplementation with escape protein are the remarkable one.

 

Treatment of crop residues with ammonia using fertilizer grade urea has received much attention, especially in Asia. Urea-ammonia treatment of straw is a technically effective and feasible on-farm technology to improve the nutritive value of fibrous crop residues.  The feeding of urea treated straw alone will lead to some increase in production, but the full potential will only be realized when the correct supplements are added. A supplement of bypass protein is the most important. Most of the oil seed plants such as noug (Guizotia abyssinica), linseed, groundnuts, rapeseed, sesame, cottonseed and sunflower are widely grown in Ethiopia. The cakes of these crops, after the oil is extracted are used as a protein supplement to low quality crop residues and hays. Work from many parts of the world (Preston and Leng 1987) has demonstrated that for practical purposes, very economical responses are obtained to 1 kg/day of cottonseed cake or similar, more conventional sources of bypass protein. In most of the Asian countries, especially Bangladesh, China, India and Pakistan, programs have been launched by combining alkali treatment and appropriate supplementation leading to practical rice-straw-based feeding systems and extension of these technologies to the target groups (Dolberg 1992; O'Donovan et al 1997; Tengyun 2000; Sharma et al 2004: Roy and Rangnekar 2006). As a follow up of global experience, national efforts are also underway in Ethiopia to evaluate and refine these interventions under local situation. Despite availability of scientific information and technology both locally (Mesfin and Ledin 2004) and globally, feed production and utilization in rural community has remained traditional. Efforts made to demonstrate and popularize feed technology in the country were very much limited to the sites around research centers or limited to participants of extension packages. Increases in animal productivity come from the development and transfer of improved feed technology and feed use. This study was therefore undertaken to evaluate the potential of feeding urea treated teff straw supplemented with linseed cake as a source of escape protein and wheat bran to lactating crossbred dairy cows under on-farm condition and to identify farmers reaction and attitude regarding the nutritional intervention.

 

Materials and methods

The study area

 

An on-farm experiment was conducted under market oriented crop-livestock production system during the dry season (January 2007 to June 2007) at three peasant associations (PA’s) (Liben Kura, Wuye Gose and Duban Agalo) of Kuyu district in north shoa zone, Ethiopia, situated about 150 km north of Addis Ababa on the road to Bahir Dar. Geographically, it extends from 9036’32’’ to 9053’00’’ north latitude and from 38003’00’’ to 38031’30’’ east longitude. It lies on the central plateau in which the most land masses are falling in Muger gorge. Its altitude and temperature ranges from 1100 to 2757masl (2500-2550 masl in experimental areas) and 10.8-25oC respectively. The area receives an annual rainfall of about 600-1450mm. Cereals (teff, wheat, barley and oats), highland pulses (peas, beans, lentils), and oil seeds are grown in this area. In this area the availability as well as the contribution of cross-breed cattle is relatively better than other regions under smallholder farmers' condition. More attention is given to the livestock production especially dairy than in the other highland areas. As a result the district was selected with the view that it could represent the dairy production system in the highlands of the country.  The PA’s with in the district were selected with the help of extension agents, representing the agro-ecology in terms of climate and market oriented crop-livestock production system.

 

Preparation of urea treated teff straw

 

The treatment of the straw was done in an over ground rectangular silo constructed two pits using pieces of wood, available at the farm on the corner location on their farms. Each pit had dimensions of about 2m * 1m * 1m, with a capacity of 150-200 kg of urea treated teff straw. The entire wall of the pit was lined with a mixture of soil and dung. A polythene plastic sheet lined the floor and side of the pit. The ratio of water: urea: molasses solution to straw used was 90:4:10:100.  Untreated straw, in batches of 10 kg weighed by using a sack, was spread in the silo over a plastic sheet layer. Ten liter of urea solution was sprinkled uniformly over the straw layers using a sprinkler. The treated straw was mixed by using a fork. Further batches were treated following similar procedures. After treating one layer of straw, it was pressed by trampling (compressed) manually before the next layer was placed on top and finally the stack was covered tightly with a plastic sheet to exclude the entrance of oxygen and prevent ammonia from evaporating for adequate fermentation. The stack was loaded with heavy materials with either stones or wood, according to the available materials. The treated straw was opened after three weeks from one side to take out the straw. The urea treated straw was aerated for a minimum of 12 h prior to feeding to facilitate the escape of free ammonia (Misra et al 2006).  The treatment of the straw and feeding were synchronized in such a way that animals got urea treated straw with out any interruption during the entire period of experiment. 

 

Experimental animals

 

Fifteen farmers, each having two lactating cross-bred cows in early to mid lactation (about 2-8 weeks after calving) were selected for the on-farm feeding trial based on their willingness to participate, commitment and presence of physical structure for monitoring feed intake. Average body weight of the selected cows was 286.855.05 kg ranging from 210 to 395 kg with an average milk yield of 4.050.41 kg/cow/day ranging from 3.0 to 5.4kg/cow/day. Based on the level of milk yield, stage of lactation, body condition and parity, the animals were divided into two equal groups (15 cows in each group):  T1 (Intervention diet) and T2 (Farmers practice/diet).

Accordingly, each farm had both treatments.

 

Experimental diets, feeding management and measurements

 

The two groups were fed with, intervention diet (T1) and farmers practice (T2): 4% urea treated teff straw ad libitum supplemented with a concentrate mixture composed of 48% linseed cake used as a source of escape protein, 50% wheat bran and 2% salt  (indoor feeding) (T1) and  as usually practiced by local farmers (grazing for 7-8h and ad libitum feeding of untreated teff straw &/or hay with some infrequent concentrate (atella, noug cake and oat grain) supplements) with out any intervention (T2). The supplement in the intervention diet was fed at the level required to fulfill nutrient requirement of the cows based on NRC (1989). The amount of supplement fed to each cow in T1 during the adaptation period of two weeks was at the rate of 0.5 kg per kg of milk production/day as per the recommendation. A reduction in concentrate mixture by 15% was made due to the feeding of treated teff straw through out the experimental period. Hence, adjustment of the concentrate supplement was made weekly based on the milk yield of each cow at the rate of 0.35 kg per kg of milk production/day and fed in the morning and evening milking time, by dividing the daily allowances into two equal parts. The treated straw was offered ad libitum ( 2 to 3 times a day) by weighing the daily allowance to ensure some amount of refusals (10-15% of straw offered) next morning. Adjustment of roughage offered was made weekly based on the amount of refusal weighed and recorded every morning. All the cows were hand milked twice a day, in the morning and in the evening. Milk yield was measured daily and recorded right at milking. The selected animals were dewormed before the commencement of the experiment. The animals had free access to water throughout the experimental period.

 

Duration, monitoring and data recording of experiment

 

The data were recorded over a period of 164 days after an adaptation period of two weeks. Field visits were carried out every two weeks to monitor the feed intake and milk yield of the animals.  The body weight of cows were measured every month by using heart girth measurement while the body condition scoring of each cow was assessed at the beginning and end of the experiment on a scale of 1 through 5, condition score  1 indicates severe under-condition and 5 indicates severe over-condition described by Wildman et al  (1982). Cows were scored on appearance and palpation of back and hind quarters only. The enumerators daily recorded the intake of roughage and concentrate and milk yield on pre-designed data recording sheet. These sheets were checked at each visit for accuracy and consistency. Feed samples were collected at monthly intervals and brought to the laboratory for further analysis. A formal survey and focused group discussion was conducted to assess the socio-economic characteristics of the participating farmers at the beginning and end of the experiment and the perception of the participating farmers at the end of the experiment regarding the feasibility of urea treatment and linseed cake supplementation along with wheat bran and salt for dry season feeding to lactating crossbred dairy cows.

 

Sampling and analytical techniques

 

Samples of the feeds obtained during the experiment were bulked, mixed, ground and analyzed for dry matter (DM), organic matter (OM) and crude protein (CP) according to the standard procedures of AOAC (1980). Neutral detergent fiber (NDF), acid detergent fiber (ADF) and lignin were determined by the method of Goering and Van Soest (1970).  The two stage in vitro technique developed by Tilley and Terry (1963) was used to determine In vitro Organic Matter Digestibility (IVOMD) of the feeds. Metabolizable energy value was estimated (EME) from the % IVOMD: ME=0.16(%IVOMD) according to McDonald et al (1995). Hemicellulose (HC) was calculated from the difference between % NDF and % ADF while cellulose was calculated from the difference between % ADF and %lignin.

 

Statistical and economic analysis

 

The data were subjected to analysis of variance (ANOVA) using the General Linear Model (GLM) procedure of Minitab statistical software version 12.21, Minitab (1998). Initial body weight was used as covariate for dry matter intake, body weight gain, and body condition score of animals to remove the effect of differing in initial weight while the initial milk yield was used as covariate to adjust milk yields during experimental period. The statistical model used was:

Yij=+ri+b(Xij-X)+eij

Where:

Yij is the dependent variable (feed intake, milk yield, body weight gain and body condition score),
  overall mean, ri effect of diet, b regression coefficient,
Xij the record of live weight/milk yield of the jth cow on the ith diet,
X the overall mean of live weight/milk yield during the initial period,
eij random variation.

 

The economic analysis was based on calculations of the total cost of production and the income from milk sales. The price of feeds and the price of milk were obtained from the market price prevail in the area during experimental period. The net profit/cow/day was calculated for the whole experimental period by deducing the cost of production from income generated from milk sales.

 

Results and discussion 

Socio-economic characteristics of participating farmers

 

The average family size of the selected households (HHs) was 7.27 members per household (HH) of which 54.13% were male while 45.87% were female members. Among the participant farmers, 20.0% were female headed HHs while the rest 80.0% were male headed HHs.  Education plays an important in the adoption of new intervention/new technologies.  Education level of the head of household was low; 53.33 % were illiterate, 40.0% had primary education and 6.67% had secondary education. All female headed HHs were illiterate. However, 86.7% of the participant farmers sent their children’s to primary and secondary schools.

 

Land is an important asset for farmers. The size of land holdings of the participant farmers ranged from about 0.5 ha in the case of marginal farmers to about 5 ha per HH in the case of large farmers. The average land holdings was 2.87 ha of which 63.95 % of land was allocated for crop cultivation, 20.93 % was for grazing land and the rest 15.12 % was reserved for native hay production. Nearly 13.33 % of the HHs was having only 0.5-1.0 ha of land and hence, they were dependent on leased land for crop and hay production from other farmers and also dependent on market purchased feeds. The term lease was mainly a fixed amount per unit of land and varied depending on the availability of rainfall and the quality of the land. The majority of the respondents   belonged to small and medium categories; 33.33 % were marginal farmers (having 0.5 to 2.0 ha of land) and 53.33% were medium farmers (having 2.5 to 4.0 ha of land). Only 13.33% of farmers were large, having more than 4 ha of land. The average number of dairy cows kept by farmers were 5.47, ranging from 2 to 17, of which the 79.27 % were cross bred dairy cows while the rest 20.73 % were local dairy cows. The average milk production per HH has a direct relationship to farm size. Almost 93 % participant farmers were selling milk and milk products (butter and/or cheese) for dairy cooperatives and for consumers in the local markets respectively.

 

Traditional feeding system

 

Marketing of teff straw is a common practice among farmers in the district. Crossbred milking cows in areas of better access to milk and milk by-products market infrastructures such as Liben Kura, Duban Aggalo and Wuye Gose are mostly sole-fed and also allowed to graze on grazing lands and crop aftermath after harvest during the dry season (Nov-June). A focused group discussion showed that almost all the participants adopted the practice of supplementing their animals with concentrate ingredients like noug cake, oat grain, and atella. Common salt was also provided to the animals by mixing with the above ingredients. Noug cake from small-scale oil processing plants in the town was the major protein supplement available and used by farmers. Some farmers occasionally use noug cake in mixture with milled and diluted/soaked oats (Avena sativa) grain (as energy supplement) and tela atella (traditional brewery residue as protein and energy supplement as reported by Yoseph Mekasha et al (2002) during milking time for better performance by milking cows and for improving the over all condition of the cow in addition to boost milk yield. However, the quantities of individual feed ingredients included in the concentrate mixtures seemed to depend on their relative availability rather than on the farmers’ conscious desire to supply better quality feed to their cows. The availability of feed was scarce and cost was high during the dry season and therefore animals receive insufficient amounts of feed most of the time.

 

Chemical composition and in-vitro organic matter digestibility (IVOMD) of feeds

 

The chemical composition and in-vitro organic matter digestibility (IVOMD) of feeds offered to experimental animals is presented in Table 1. The basal diet (natural pasture hay and untreated teff straw) available for feeding during the dry season was low quality and do not meet production requirement of animals (Table 1).


Table 1.  Chemical composition, in-vitro organic matter digestibility and estimated metabolizable energy of feeds (Mean standard deviation, 3 replicates per each sample)

Measurement

Untreated

teff straw

Treated

Teff straw

Natural pature hay

Concentrate mixture

Noug cake

Tella Atellaa

Oat

grain

Dry Matter %

920.4

430.6

91.20.2

930.3

93.10.3

13.2

91.20.2

AS % of DM         

 

 

 

 

 

 

 

Organic matter

92.90.3

93.90.4

90.40.1

91.40.25

88.90.2

98.0

96.40.1

Crude Protein

4.30.4

8.90.5

6.00.3

24.00.3

35.50.3

21.0

8.00.2

NDF

74. 50.2

70.00.2

73. 80.2

47.90.4

33.30.3

59.5

38.20.3

ADF

43.40.2

47.20.3

45.50.2

20.30.3

28.20.4

21.2

20.60.2

Lignin

6.50.02

8.00.02

8.30.02

4.80.03

7.40.04

ND

4.80.03

Hemicellulose

31.10.05

22.80.1

28.30.04

27.60.07

5.10.08

38.3

17.60.1

Cellulose

36.90.15

39.20.2

37.20.2

15.50.25

20.80.3

ND

15.80.2

IVOMD

53.20.32

57.40.4

54.30.3

75.00.2

67.30.3

82.31

66.40.3

EME, MJ/kg

8.510.2

9.180.3

8.690.2

12.00.2

10.770.2

13.17

10.60.2

aSource: Yoseph Mekasha et al (2002);  Yoseph Mekasha et al ( 2003)

bND: Not determined; DM: Dry matter; NDF: Neutral detergent fiber; ADF: Acid detergent fiber; IVOMD: In-vitro organic matter digestibility; EME: Estimated metabolizable energy


Fibrous crop residues and natural pastures in the dry season were of low nutritive value and were below the capacity to meet the nutritional requirement of livestock, (Smith 2002). A considerable change in nutrient content was observed as a result of urea treatment. Ammoniation of teff straw with urea doubled the CP content from 4.3 to 8.9 % (increased by 107%) due to retention of ammonia N (binding of ammonia) to the straw (Dias-da-Silva and Sundstol 1986; Zorilla-Rios et al 1991; Srinivasulu et al 1999). There was also an increase in IVOMD by 7.9 % (from 53.2 to 57.4 %) when teff straw was treated with urea which was due to better solubilization of hemicellulose and swelling of cellulose during urea ammonia treatment (Singh et al 2001) which is in agreement with Preston and Leng (1987) who reported that this practice increases digestibility by 5-10% units and the N content of the treated straw as compared to untreated straw. 

 

Regarding the cell wall constituents, urea treatment reduced the NDF and hemicellulose contents of teff straw by 6.04% and 26.69% respectively while the ADF, lignin and cellulose contents increased by 8.76%, 23.08% and 6.23% respectively which was due to binding of ammonia with the straw (Srinivasulu et al 1999) and also due to solubilization of hemicellulose by the action of ammonia evolved from urea (Srinivasulu et al 1999; Misra et al 2006). These changes could be partly a result of addition of 10% molasses in the treated straw.

 
Dry matter intake (DMI)

 

The daily DMI data is presented in Table 2.


Table 2.  Effect of feeding urea treated teff straw supplemented with linseed cake based concentrate mixture on feed intake and milk yield of lactating crossbred dairy cows (LS-means and SD)

Measurement

Intervention diet (T1)

Control (T2)

SD

Dry matter intake (DMI), kg/day

 

 

 

Grazing, h/day

-----

7-8h*

 

Urea treated /untreated teff straw (hay)

6.23a

4.74b

0.093

Concentrate mixture

2. 87a

1.75 b

0.080

Total DMI, kg/day

9.09a

6.50 b

0.157

Roughage proportion, %

68. 73b

72.81a

0.495

Concentrate proportion, %

31.27a

27.19b

0.495

Straw intake/100kg  of Live weight

2.04a

1.71b

0.041

Total DMI/100kg  of Live weight

2.97a

2.34b

0.059

Average milk yield, kg/cow/day#

7.14a

3.66b

0.163

Increase in milk yield, kg/cow/day

3.48

----

 

 ab means in the same row for each parameter with different superscripts are  significantly different (P<0.01); LS-means: Least square means; SD: Standard deviation

*The dry matter intake through grazing was not considered

#Adjusted by covariance for milk yield during pre-experimental period


Significant (P<0.01) improvement in DMI was observed due to feeding of the intervention diet in lactating crossbred cows over farmers diet (control).  The voluntary DMI of roughage component of the ration (kg/100kg live weight) ranged from 1.49 to 2.43 kg with a mean DMI of 2.04 and 1.71 kg/100kg in T1 and T2 respectively. This variation is understandable given the variability in lactation stage, parity, age and the live weight of the cows provided by the different participant farmers. There was an increase (P<0.01) in teff straw DMI (kg/100kg live weight (LW)) by 19.3 % in T1 over T2 which was in agreement with the observation reported by Prasad et al (1998) that the DMI/100kg body weight was significantly (P<0.01) higher on urea treated rice straw than on untreated straw in crossbred dairy cows and Singh et al (2001) in crossbred heifers, which may be due to improved palatability.  However, the obtained result was less than the previous works reported by Dolberg (1992) and Preston and Leng (1987) who indicated that this practice increases acceptability and voluntary intake of the treated straw by 25-50% as compared to untreated straw. The lower response in the present study might be due to a significantly higher (P<0.01) concentrate proportion in T1 (31.3% of the total ration) than T2 (27.2 % of the total ration) resulting in substitution of the straw by the supplement in T1 than T2 (Chenost and Kayouli 1997). As a rule of thumb, the role of supplement ceases to be ‘’catalytic’’ when it exceeds about 30 % of the DM. Beyond this point it assumes a major role and substitution occurs (Preston 1986). Total DMI of the ration in T1 (2.97 kg/100kg LW) was also higher (P<0.01) than T2 (2.34 kg/100kg LW). The amount of DMI consumed through grazing by cows in T2 was not considered and this also may have some contribution to the low straw and total DMI (P<0.01) (kg/100 kg LW) in T2 than T1.

 
Milk yield

 

The milk yield data is also presented in Table 2.  There was no significant (P>0.05) difference between the two groups in initial milk yield. However, feeding of intervention diet resulted in a highly significant (P<0.01) increased in daily milk yield by 3.48 kg (7.14 vs. 3.66 kg) in addition to supplying the calf, which is 95.08 % higher over the control (T2) group (Table 2). Similar results also reported by Vu et al (1999) indicated that cows in urea treated rice straw supplemented diet had significantly higher milk yield than for unsupplemented animals. The feeding of urea treated straw alone can give extra 0.10-0.15kg live weight in growing and 1-1.5 kg milk in lactating animal per day per animal (Khan and Davis 1981; Perdock et al 1982) which is lower than the obtained result. This is due to the bypass protein through linseed cake supplementation in addition to increased palatability, N content, digestibility, nutritive value of the straw as a result of urea treatment. Hence, the improvement in milk yield may be explained by the fact that the ME:CP ratio balanced in the ration and subsequent maintenance of ammonia content in the rumen lead to an improved ruminant environment for microorganisms. Therefore, digestibility and DM intake of teff straw and other feedstuffs was increased. It is well established that ruminants fed low-N roughages respond to a source of protein (Preston and Leng 1987) since such protein should remain relatively undegraded in the rumen. According to Saadullah (1984) it was clearly demonstrated that the potential for enhanced roughage utilization, provided a functional rumen environment is created by correct supplementation and additional amino acids are supplied in the form of protein which escape (partially) the rumen. It has been recognized that intake and utilization efficiency of crop residues are influenced by the rate of rumen fermentation (Van Soest 1982) and the balance of nutrients absorbed in the intestines.  Higher animal performances were reported for slowly degrading N sources with high undegraded protein (UDP) than rapidly degrading ones with low UDP (Gizachew 1993).

 

Body weight gain and body condition of animals

 

The body weight and body condition data are presented in Table 3. Milk yield had a higher priority for the selection of the cows and division of the treatment groups and, therefore, initial body weight and body condition score had high variation with in the group. The Significantly higher (P<0.01) final body weight, total body weight gain(loss), body weight gain(loss)/cow/day  and final body condition score  were obtained in intervention diet (T1) over farmers practice (T2) (Table 3).


Table 3.  Effect of feeding urea treated teff straw supplemented with linseed cake based concentrate mixture  on body weight gain and condition score of lactating crossbred dairy cows (LS-means and SD)

Measurement

Intervention diet (T1)

Control (T2)

SD

No. of cows

15

15

 

Body weight of cows, kg

 

 

 

Initial weight

306.0a

267.6b

8.274

Overall mean of initial weight

286.8

286.8

55.05

Unadjusted final weight

327.47

265.60

8.567

Adjusted final weight*

308. 86a

284.21b

3.682

Unadjusted weight change

21.47

-2.0

3.026

Adjusted weight change*

22.06a

-2.59b

3.682

Unadjusted gain(loss)/cow/day, kg/day

0.131

-0.0122

0.019

Adjusted gain(loss)/cow/day, kg/day*

0.134a

-0.016b

0.023

Body condition score of  cows (0-5)

 

 

 

Initial

2.34

2.38

0.025

Final

2.60a

2.22b

0.062

ab means in the same row for each parameter with different superscripts are  significantly different (P<0.01); LS-means: Least square means; SD: Standard deviation

*Adjusted by covariance for initial weight:

 Adjusted mean final weight/ weight change/gain(loss) per cow per day = Y-b(x-X)

Where: Y the record of unadjusted mean final weight/ weight change/gain(loss) per cow per day, b estimate of regression coefficient: 0.96892066 for final weight, -0.03107934 for weight change and -0.0001895082 for gain(loss) per cow per day, x the record of unadjusted mean initial weight, X the overall mean of live weight during the initial period


According to Kayouli (1996) the consumption of treated forages during the dry season often accompanied  improvement in body condition of the animals and maintenance of live weight; they are more resistance to disease and their coat improved (brighter hair). Cows in T1 group increase in weight gain by 134 g/cow/day while the cows in T2 group lose 16 g/cow/day resulted in poor body condition in T2 cows (Table 3).  The results obtained in this experiment agrees with Rashid et al (2001) who reported that the weight gain ranged from 134- 232 g/day was achieved in dairy cows in urea treated rice straw together with concentrate mixture. Nutritional supplementation is one of the most important determinants of body weight, especially in postpartum cows (Sasser et al 1988; Butler and Smith 1989). However, Vu et al (1999) reported that urea treated rice straw supplementation did not demonstrate an improvement in body weight and body condition score over the control in dairy cattle due to the high variation with in the groups.

Economic analysis

The cost of grazing for the T2 groups was not considered while the total cost of production (feeds, urea, labor for treating straw and material including plastic sheet used for sealing the treated straw) was considered since other variable cost (medicaments) was the same for both groups. The net profit increased from ETB 4.73/cow/day in the control group (T2)  to ETB 9.39/cow/day in T1 group due to the improvement in milk yield coupled with a 1.35 % cost reduction/kg of milk produced in T1  over T2. Hence, this study demonstrated that feeding the intervention diet to crossbred dairy cows increased the net profit for farmers to ETB 4.66/cow/day over the farmers’ practice (Table 4).


Table 4.  Economic evaluation of feeding urea treated teff straw supplemented with linseed cake based concentrate mixture in lactating crossbred dairy cows

 

Intervention diet (T1)

Control(T2)

Cost of untreated straw (hay), Ethiopian birr (ETB) #$

555.14

426.40

Cost of straw treatment

 

 

Cost of molasses#

111.03

---

Cost of urea#

177.65

---

Cost of plastic@

140

---

Cost of labor@

56

---

Cost of grazing

 

---

Cost of supplement (concentrate mixture), ETB#

933.27

598.83*

Total Variable cost, ETB

1973.07

1025.23*

Cost /cow/day

12.03

6.25*

Cost /cow/kg of milk

1.685

1.708*

Change in variable cost, ETB

947.84

 

Gross profit from sale of milk, ETB"

3512.88

1800.72

Gross profit over control, ETB

1712.2

 

Net profit, ETB

1539.81

775.49

Net profit over control, ETB

764.32

 

Gross profit/cow/day, ETB

21.42

10.98

Net profit/cow/day, ETB

9.39

4.73

Net profit over the control/cow/day ETB

4.66

 

*With out considering the amount consumed and cost through grazing

#The unit costs prevalent during the experimental period were 0.5 ETB/kg of untreated straw (hay), 2.75 ETB/kg of linseed cake, 2 ETB/kg of noug cake, 1.0 ETB/kg of wheat bran, 4 ETB/kg of urea, 1.0 ETB/kg of molasses, 2 ETB/kg of oat grain, 0.235 ETB/liter of atella and 1.2 ETB/kg of salt. Costs of supplement(concentrate mixture) were 1.844 ETB/kg and 0.703 ETB/kg in T1 and T2 respectively

@Labor cost (man day) was 8 ETB while cost of plastic sheet per meter was 10 ETB

"Selling price of milk was 3 ETB/kg of milk

$1 USD~ 9.9 ETB


Participants observed that besides increase in milk production, most of the cows in intervention diet showed symptoms of heat at the proper time in contrast to the cows in group T2. In view of the above, the economic returns may be higher if the positive long-term impact of the intervention diet on production, reproduction, body condition and general health of the animals are also taken into account. Considering the cost of production and the market price of milk prevailed in the area during experimental period, the intervention diet was found to be economical compared to farmers practice.

Farmers' perception

Almost all the participants reported that, the consumption of treated straw by cows was achieved after a week from when this type of feed has been introduced to the cows and increased productivity. Participants noticed that the benefits of feeding the intervention diet were not visible immediately. It took 3 to 4 weeks depending upon the adaptation of the new diet by the cows. Hence, it is essential to aerate urea treated straw for some hours prior to feeding to facilitate the escape of free ammonia so that the cows could easily adapt the treated straw with in short period of time. Farmers noticed that cow’s inT1 group eat the treated straw more quickly especially when it is given ad libitum. Further more, after feeding the intervention diet, an increase in the amount of water consumed by the animal, an increase both in milk production and a general improvement to body condition of cows, an improvement in fertility levels (cows show more intensely the characteristic of being on heat), and an increased production of more manure which is softer and darker in color also perceived by farmers. All the participants readily accepted the practice of feeding the intervention diet and were willing to continue in future, if the concentrate ingredients, urea, molasses and plastic sheet were available in the local market in affordable price and milk could be sold at an assured rate of ETB 3 and above/kg of milk in the area. However, they expressed apprehension about the availability of each ingredient, urea and materials like plastic sheet for making the urea treatment in the local market with an affordable price. In situations, however, where the required concentrate ingredients are either sold at higher price or unavailable, the participants perceived no advantage in adopting improved practices.

 

Conclusion and implications 

 

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Received 6 December 2008; Accepted 7 April 2009; Published 1 May 2009

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