Effects of urea-molasses multi-nutrient blocks as a dietary supplement for dairy cows in two milk production systems in north-western Ethiopia

E Tekeba^1,2, M Wurzinger² and W Zollitsch²

¹ Andassa Livestock Research Centre (ALRC) P.O.box 27, Bahir Dar, Ethiopia
² BOKU - University of Natural Resources and Life Sciences Vienna,
Gregor-Mendel-Strasse 33, A-1180, Vienna, Austria
tekeba333@yahoo.com

Abstract

A field study was conducted in the north-western part of Ethiopia to evaluate the effect of urea molasses multi-nutrient block (UMMB) supplementation on productive and reproductive performance and economics of feed supplementation in local Fogera (F) and Holstein Friesian (HF) x F crossbred dairy cows (F₁) during the dry season. The study was conducted simultaneously in a rural subsistence crop-livestock production system using 18 second and third parity Fogera cows and in a market-oriented peri-urban livestock production system using 16 HF x F crossbred dairy cows of similar parity as the Fogera cows. All cows were in their early stage of lactation and the feed types used were the existing dry period farm-specific feeding practices without (control) and with UMMB supplementation (experimental diet).

Regardless of the production systems, dairy genotypes showed a significant improvement in daily saleable milk and milk energy off-take, milk quality traits, postpartum ovarian activities, body weight gain, body condition and benefit-cost ratio due to UMMB supplementation. Even though supplementation with UMMB had an overall positive effect on biological as well as economic parameters, the response of cows in the two production systems varied for different traits: crossbred cows showed a particularly strong response in daily milk off-take, improved postpartum oestrus activity and had a greater benefit- cost ratio than Fogera cows in the rural subsistence production system. In general, UMMB was shown to be a viable tool for securing sufficient energy and nutrient intake under on-farm conditions. However, cows with a greater genetic potential will show a higher performance if supplied with sufficient quantities of nutrients and energy than a local genotype. Therefore, under situations of restricted availability of UMMB, first priority in supplementation should be given to crossbred cows over local cows.

Key words: crossbred cattle, Fogera, feed, market-oriented, subsistence

Introduction

Dairying is practiced in most regions of Ethiopia by involving a vast number of mainly small scale, subsistence or market oriented farms (Sintayehu et al 2008). Based on market orientation, scale and production intensity, the dairy sector is categorized into 3 major production systems in Ethiopia (Gebrewold et al 2000). These include the traditional smallholders, privatized state farms and urban and peri-urban farms. The traditional smallholders contribute 97 % of the total national milk production and 75 % of the commercial milk output (Ahmed et al 2004), while the urban and peri-urban dairy production system produces only 2 % of the total milk output (Ketema 2000). According to Ahmed et al (2004), the smallholders are largely dependent on low yielding indigenous breeds which produce between 400 and 680 litres of milk/cow and lactation. In contrast, the urban and peri-urban dairy production system is market oriented and mainly based on the use of pure exotic and crossbred cows.

Despite its socio-economic contribution, the dairy sector in tropical countries, including Ethiopia is frequently challenged with various constraints. Among these, nutritional limitations are often the overriding ones and a concern in livestock development strategies (Nyambati et al 2003; ELDMPS 2007; Asaminew and Eyassu 2009; Belete et al 2009; Mendieta-Aracia et al 2011). According to these sources, the basal diets of ruminants during the dry season are fibrous crop residues and pasture, which are low in their nutritional value. On the other hand, insufficient intake of energy, protein and minerals is associated with sub-optimal productive and reproductive performance of dairy cows (Indetie 2009).

An average 35 % deficiency in feed supply can be expected in Ethiopia even during normal years and this figure may rise to 70 % during drought years (ELDMPS 2007). This problem is likely to become more serious as a growing human population demands more land for crop production. The main reasons for feed shortage in Ethiopia are therefore related to shrinking grazing lands as a result of expansion of arable cropping; the low contribution of improved forage as livestock feed (0.25 % ; CSA 2010) and high prices of concentrates which further exacerbate the tight situation (Asaminew and Eyassu 2009; Belete et al 2009; Dejene et al 2009; Teshome 2009). On the other hand, large amounts of molasses have been produced as by-product of sugar in four sugar factories in Ethiopia and its supply is expected to substantially increase in the near future due to the expansion of the existing factories and a number of new plants currently under construction and in the planning phase (Adugna 2007; GTP 2010).

The roughages, including pasture and crop residues which form the basis of the diet, are usually rather low in their nutrient content and supplementation is needed particularly with fermentable energy and protein sources. Urea molasses multi-nutrient blocks (UMMB) have been used as a livestock feed supplement in comparable environments in a number of countries and encouraging results have been reported (Plaizier et al 1999; Elmansoury et al 2002; Seyoum and Fekede 2006). A positive response to dietary UMMB supplementation can therefore be expected for the productive and reproductive performance and the benefit-cost ratio in local and crossbred dairy cows in different dairy production systems. Nevertheless, data are lacking for the effects of UMMB-supplementation under on-farm conditions in Ethiopia, particularly including local Fogera and their 50 % Holstein Friesian crossbreds.

Therefore, the objective of this study was to evaluate the effect of UMMB supplementation on the performance of local Fogera cows and their 50 % Holstein Friesian crossbred in two different livestock production systems. Response traits include saleable milk off-take, milk composition, estimated body weight change, body condition, reproductive performance and the benefit-cost ratio of feed supplementation during the dry season.

Materials and methods

Study sites

This study was conducted at Fogera and Bahir Dar Zuria (BDZ) districts during very dry months (December – May) where feed shortage is very critical. Fogera district is situated at 11⁰58’ latitude, 37⁰41’ longitude and at an altitude of 1774 to 2410 meter above sea level (masl). The mean annual rainfall is 1216 mm (1103 to 1336 mm) (Fogera Woreda Pilot Learning Site Diagnosis and Program Design 2005). The minimum and maximum daily temperatures of the area are 10 and 28 ⁰C, respectively (Dejene et al 2008).  The major feed types in the study area include natural pasture, hay, crop residues from tef (Eragrostis tef), maize, rice and finger millet with hardly any concentrate and improved forage supplementation. The Fogera cattle are the dominant cattle breed in the area which thrives well in marshy areas and are kept for draft, milk and meat purposes (Alberro and Solomon Haile-Mariam 1982). This production system is characterized as crop- livestock production where more than 66 % of milk produced is processed into butter due to absence of a milk market and transportation (Belete et al 2009; personal observations).

On the other hand, BDZ district is located at an altitude of 1700-2300 masl. The area receives an average annual rainfall of about 820 to 1250 mm. The minimum and maximum daily temperatures of the area are 10 and 32 ⁰C, respectively. The major feed resources for cattle are natural pasture, crop residues hay and non-conventional feedstuffs like local brewery by-products but the supply of improved forage is not common and concentrate supplementation generally low. However, those farmers who own crossbred cows usually supplement the diets with oil seed by-products like nug (Guizotia abyssinica) cake, wheat bran and local brewery by-products. According to Asaminew and Eyassu (2009), due to better extension and AI services in the area, the number of crossbred dairy cows in this district is higher as compared to adjacent districts. The average milk production of local cows in the district is 1.2 litres and the corresponding value for crossbred cows is 5.2 litres.

Experimental design

Prior to the actual feeding trial, discussions with districts officials and model farmers were held and secondary data were reviewed about dry season feed supply and constraints, farmers feeding strategy and livestock product marketing. Based on this information, localities and farmers were selected purposively which should represent the regional rural subsistence and peri-urban, market oriented dairy production systems.

Experimental cows from Fogera and BDZ districts were selected based on their lactation number, stage of lactation, current milk yield, body condition and health status. The selected cows were distributed evenly to a control and an intervention diet. The control diets used were the traditional feeding practices of the farmers in their respective production system and the intervention diet included UMMB as a supplement to the usual feeding regime. The selected farmers were trained on the production and use of UMMB and on data recording.

Management and feeding

A total of 18 multi-parous lactating local Fogera cows of parity two and three in the Fogera district and 16 multi-parous Fogera x Holstein Friesian (HF) crossbred dairy cows in BDZ district with a similar distribution of parities as for the Fogera cows were used over a period of 5 months (December 2010 to April 2011). In both livestock production systems cows were in their early stages of lactation. Before the start of the trials, cows were de-wormed using Albendazol 2500 mg (one bolus/250kg live weight), were vaccinated against anthrax, bovine pasteurellosis and lump skin disease. All animals had a close supervision by a veterinarian in charge of each district. All cows were hand milked twice a day after having been suckled by their calves for about 1-2 minutes. Body weight of the cows was estimated every two weeks by measuring heart girth of the cows and using a regression equation developed at Andassa Livestock Research Centre (Addisu 2010):

Body weight (kg) = 2.126 * heart girth (cm) – 87.39                                                            

At the same time, Body Condition Score (BCS) was judged by two independent observers and the mean of the two scores was recorded as the body condition of the cows. The BCS estimation was done according to the procedure suggested by Rodenburg (2000), using a scale from 1 (very thin) to 5 points (over conditioned) which combined both visual and tactile appraisals. All animals were managed as commonly practiced by the farmers and breeding was not controlled and done at any time when the cows were observed as being in heat. Cows were inseminated either by a local bull or artificially by skilled AI technicians.

UMMBs were manufactured at Andassa Livestock Research Centre and transported to the respective district every 10 days. UMMBs were formulated from 37 % molasses, 10 % urea, 10 % cement, 25 % wheat bran, 15 % nug (Guizotia abyssinica) seed cake and 3 % common salt (Bediye et al 2009). A rectangular wooden frame of 30*20*20 cm depth, length and width, respectively, was used to produce a 5 kg UMMB.

In the two livestock production systems feed supplementation including UMMB and management were different. For example, Fogera cows in the rural subsistence area were grazing between 9 am and 6 pm either on communal or private grazing lands. Crop residues were fed during the morning and evening hours. UMMB was supplied early in the morning between 6-8 am before milking and between 6-7 pm in the evening after milking. On the other hand, crossbred cows in market oriented peri-urban production system, were usually offered hay, a mixture of local brewery by-products, wheat bran and nug seed cake after milking and before they went out for grazing and UMMB supplementation continued for an hour after the morning supplementation and the cows remained in the pasture between 9-12 am afterwards. Between 12 am and 3 pm, crossbred cows were usually kept around the homestead and allowed to lick the block for about 3 hours. During the afternoon, they went out again for grazing between 3 -5 pm. Similar to the morning feeding, supplements were given during the evening before milking and then UMMB was offered after milking for about an hour.

Data recording

After the adaptation period, daily milk off-take was measured using graduated plastic jug by the farmers and paid enumerators assisted recording. Representative milk samples in triplicate were taken every two weeks and were analyzed for their composition using a Lactoscan milk analyzer[1]. Individual block offered to each cow was recorded every time to calculate the daily intake. Estimated body weight changes, BCS, medicaments given and feed costs were collected during the whole period at the two sites. Cows inseminated and date of insemination was also recorded. Milk Energy off-take (MEO) and Energy Corrected Milk (ECM) were calculated based on the equations as published by Tyrrell and Reid (1965a and b):

MEO = (0.0384 fat + 0.0223 protein + 0.0199 lactose – 0.108) * milk yield

Where MEO = Milk Energy off-take (MJ/d); units of measurement are g kg^-1 milk for fat, protein and lactose, whereas milk yield is expressed in kg/day.

ECM = Milk yield * (40.72 (% fat) + 22.65 (% protein) + 102.77)/314

Where ECM = Energy Corrected Milk (liters/d)

Using check lists, farmers’ perception about the technology was collected during routine visits and workshops. Data on feed costs and price of milk were collected for partial budgeting. Using this information, net return/cow/day, net return/liter of milk, feed cost/liter of milk and benefit- cost ratio were calculated. Net return/cow/day was calculated as the difference of daily milk sold per cow minus daily feed costs per cow. Feed costs/liter of milk were calculated using feed costs per day divided by daily milk off-take, whereas net return/liter of milk was calculated as net return/cow/day divided by milk off-take/cow/day. The benefit- cost ratio was calculated from change in net return between the control and supplemented group divided by change in feed costs.

Statistical analysis

Data regarding milk off-take, milk composition, milk energy off-take, estimated body weight gain, BCS, feed cost/l of milk, net return/cow/day and net return/l of milk were analyzed using the Mixed Linear Model procedure of SAS (2009). The postpartum oestrus was analysed using Chi-Square test and benefit-cost ratios were analysed using descriptive statistics. All collected data were subjected to analysis of variance, including the initial milk off-take and estimated initial body weight and initial BCS as co-variables for analysis of the respective response trait. For BCS, differences between treatments were analysed using the Kruskal-Wallis test (non-parametric one way procedure; SAS 2009). The results are presented as Least Square Means and residual standard deviation (s_e) and significance is defined at (P < 0.05), unless stated otherwise. The statistical model used for data analysis was:

У_ijklm = μ + δ_i + α_j(_i) + λ_k + β_l + X + ε_ijklm

Where:

У_ijklm = the dependent variables, milk off-take, milk composition, MEO, estimated body weight gain and BCS

μ = the overall (constant) mean

δ_i = fixed effect of i^th diet (i = control, UMMB)

α_j(_i) =  random effect of j^th cow within i^th diet

λ_k = fixed effect of k^th lactation number (k = 2, 3)

β_l = fixed effect of  l^th week (l = 1…12)

X = initial milk off-take; initial estimated body weight; initial BCS

ε_ijklm = residuals

Economic traits were analysed with similar model but without co-variables.

Results and discussion

Effects of UMMB on productive and reproductive performance

Data related to average saleable milk and milk energy off-take and selected parameters of milk quality traits are presented in Table 1.

A highly significant (P<0.01) difference was observed in daily milk off-take as a result of UMMB supplementation for both production systems. It should be noted that the differences between production systems are to a great extent caused by the breed effect, but due to the design chosen for this study, the production system is completely confounded with breed. While this simply reflects the reality in the field, no differentiation can be made between genetic and environmental effects for any of the response traits.

The relative improvement in average daily energy corrected milk (ECM) off-take due to supplementation was similar in the rural subsistence (RS) and the peri-urban (PU; 28 %; Table 1) production systems. Due to breed-related differences in milk fat and protein content, the improvement in milk energy off-take that resulted from UMMB supplementation were 28 and 30 % for RS and PU production systems, respectively. A greater positive response of 55 % in milk off-take was observed in local cows in Bangladesh due to UMMB supplementation (Akter et al 2004). The lower milk off-take response of cows in this study as compared to the Bangladesh case may be related to the difference in nutrient and energy intake and management systems. Leng (1997) found an increase in milk yield due to UMMB-supplementation for lactating dairy cows in India of 30 %, which is closer to the values reported herein. In a Vietnamese study, supplementation of crossbred dairy cows with UMMB resulted in an 11 % increase in milk yield (Doan Duc Vu et al 1999).

In addition to milk off-take, supplementation of UMMB significantly (P<0.05) improved the butter fat content of milk in RS (7 %) and PU (6 %; Table 1). But UMMB supplementation to crossbred dairy cows in Vietnam (Bui Xuan An et al 1993) resulted in a much higher (15 %) increase in milk fat content than in the present study. This may be due to the 95 % greater UMMB and nutrient intake for the Vietnamese group (514 vs 1000 g). A similar study (Upreti et al 2010) using crossbred dairy cows in Nepal indicated that UMMB supplementation resulted in an increase in milk fat content that was very similar (6%) to the present findings. Other related research also indicated that UMMB, through its balanced fermentable nitrogen and energy content, improved milk fat content in dairy cows (Leng et al 1991; Doan Duc Vu et al 1999; Sudhaker et al 2002; Alam et al 2006).  Even though slight improvements were observed in protein content of milk following UMMB supplementation, its effect was not significant (P>0.05) in both production systems. A number of previous studies (Bui Xuan An et al 1993; Misra et al 2006; Reyes Sánchez et al 2006) also indicated that UMMB or/and concentrate supplementation has no effect on the protein content of milk. On the contrary, Sahoo et al (2009) reported a significant improvement in the protein content of local cows’ milk when they were supplemented with UMMB.

Similar to the daily milk off-take, a significant (P<0.05) improvement in daily fat and protein off-take was observed due to UMMB supplementation in both production systems. This increase is mainly a result of the changes in milk off-take and hence the absolute differences are greater for the peri-urban production system in which higher yielding crossbred cows are utilized than for the rural subsistence production system, in which farmers keep local Fogera cows.

The average daily UMMB intake of Fogera cows in RS in this study was 334 g whereas the corresponding figure for crossbred cows in PU was 514 g. The greater UMMB intake by crossbred PU-dairy cows may have been related to the greater quantities of nutrients and energy required for their higher milk off-take; this was accompanied by longer time periods during which they were allowed consuming the blocks and by a greater requirement for body maintenance of crossbred cows. The study conducted in Thailand (Narong 2007) using crossbred cows also indicated that cows consumed on average 520 g UMMB per head and day.

The increase in milk off-take and milk constituents for the UMMB supplemented dairy cows consequently led to a significant (P<0.05) improvement in milk energy off-take for both production systems (Table 1). However, the Fogera cows at RS were superior to crossbred cows at PU in their milk energy content per liter of milk: for example, supplemented cows at RS were 8.3 % higher than supplemented cows at PU (Figure 1). An on-station study in which the same breeds were used (Tekeba et al,  unpublished) also indicated that the higher protein and energy intake from UMMB supplementation resulted in a better milk energy output than in the control groups.

Irrespective of the production system, UMMB supplementation also substantially improved the estimated body weight gain of dairy cows as compared to non-supplemented cows (Table 1). Similar to this finding, UMMB supplementation exerted a positive effect on body weight gain irrespective of the breed in a previous on-station experiment (Tekeba et al unpublished). A similar response to consumption of urea-molasses blocks was also reported for growing buffalos (Jian-Xin Liu et al 2007). The positive influence of the UMMB supplementation on estimated body weight gain is paralleled by a significant (P<0.05) 0.4 to 0.5 score points improvement of BCS of dairy cows in RS and PU production systems, respectively. Contrary to these findings, UMMB supplementation failed to show positive effects on body weight and body condition of crossbred dairy cows under smallholder conditions in Vietnam (Doan Duc Vu et al 1999).

In addition to the improvement in body weight and body condition, UMMB supplementation also seemed to have positively influenced reproductive performance. The result indicated in Table 1 shows that more of the supplemented than of the control cows were inseminated, although the numbers of observations were too small to result in significant differences. Overall, cows in the peri-urban livestock production system seemed to have a slightly better reproductive performance than the Fogera cows in the rural subsistence-oriented production system. Similar to this finding, it was concluded from a previous on-station study (Tekeba et al unpublished), which involved Fogera and crossbred dairy cows, that the effect of UMMB on postpartum oestrus was more prominent in crossbred than in local Fogera cows. These results are in agreement with the work of Khanum et al (2010) who found that UMMB supplementation improved post-partum ovarian activity in addition to an increase in milk yield, feed intake and weight gain of dairy cows.

Effects of UMMB on selected economic traits

Taking into account saleable milk off-take and cost of feed only, the benefit-cost ratio for Fogera and crossbred dairy cows in their respective production system were 2.64 and 5.53, respectively (Table 2). Upreti et al (2010) concluded from their study with crossbred dairy cows in Nepal that due to UMMB supplementation an additional net profit was obtained of 10.77 NRs [1 USD = 75.1880] per day. The improvements in net return per day due to UMMB supplementation were 24 and 45 % for the rural subsistence-oriented production system (Fogera) and the peri-urban farms (crossbred), respectively. The economic gain obtained under farm conditions was better than that observed in the on-station experiment by Tekeba et al (unpublished). The differences to the current study may be related to the difference in stage of lactation between the two experiments: cows were in their mid and late stage in the on-station, but in early lactation in the on-farm trial. For the net return per day a significant (P<0.05) difference was observed between supplemented and control groups of cows in both production systems (Table 2). Due to their higher milk yield, cows in the peri-urban livestock production system which were supplemented with UMMB showed a higher net return per day than their control group and PU cows were clearly superior to cows in the rural subsistence-oriented production system

Farmers’ perception on the use of UMMB

During routine visits, at the time of distribution of the blocks and a workshop conducted at the end of the feeding trial, the following farmers’ and development agents’ observations were collected and summarized. Notable improvements in milk off-take, body condition, reproductive performance, health status of the cows and an increased straw intake were the major observations compiled from the 34 respondents (Table 3).  

Contrary to its positive effect, some farmers also raised the following concerns in relation to a potential scaling up of the technology:

• Future uncertainties about the supply of molasses/blocks in the local market.
• The currently insufficient knowledge of the farmers on the production and use of the technology coupled with the poor linkage among stakeholders.
• A market access problem exists for milk and milk products which results in the loss of interest to invest in the technology by some of the smallholder farmers in RS production system.

For future action, the following points were suggested by the farmers and other stakeholders:

• Training of farmers and demonstration of the technology through farmers training centres.

• Training of extension agents, researchers and producer youth groups on the technology.

• Local government, extension department, research, cooperatives, sugar industries and relevant NGOs need to be involved in the transfer of the technology and create a link among themselves

• Establishment of more dairy cooperatives and specialised youth UMMB producer groups.

• The use of revolving fund approach for mass production of the block by dairy cooperatives and/or specialised youth groups and creating of market linkage

• Assigning facilitators for transfer and scaling up of the technology at district level.

• Monitoring and evaluation system for technology dissemination and adoption.