Effects of dietary supplementation with urea molasses multi-nutrient block on performance of mid lactating local Ethiopian and crossbred dairy cows

E Tekeba, M Wurzinger*, L Baldinger* and W J Zollitsch*

Andassa Livestock Research Centre, P.O.box 27, Bahir Dar, Ethiopia
tekebanega@gmail.com
* BOKU-University of Natural Resources and Life Sciences Vienna, Gregor-Mendel-Strasse 33, A-1180, Vienna, Austria
maria.wurzinger@boku.ac.at   ;   werner.zollitsch@boku.ac.at

Abstract

An experiment was conducted on station, using a nested design in order to evaluate the effects of a Urea Molasses Multi-Nutrient Block (UMMB) supplementation of typical dry season, roughage based diets on the performance of mid lactating local Fogera and their F₁ Holstein Friesian crosses in Ethiopia. Eight cows each from both breeds were assigned to a forage-based control diet and an experimental diet with UMMB supplementation.

Highly significant differences were observed between treatments for most production traits. However, Fogera and crossbred dairy cows showed a different response pattern for some traits. Crossbred dairy cows were superior over Fogera for milk production, reproductive performance and benefit-cost ratio regardless of UMMB supplementation. Conversely, Fogera cows had higher milk solid contents and supplementing them with UMMB had a greater effect on milk fat than in crossbred cows. It is concluded that supplementing dairy cows with UMMB during the dry season is basically a helpful measure to maintain production. Depending on the availability of UMMB, priority in supplementation however, should be given to cows with a high genetic potential for milk production.

Keywords: Fogera, mid-lactating, on-station, roughage-based, supplement

Introduction

Farmers in the tropics and developing countries often rely on the use of exotic genotypes to crossbreed their indigenous cattle with the aim to improve their milk yield. Because of the specific environmental stressors, including climatic factors, pathogen pressure and deficient feed supply, the performance of the animals originating from such a crossbreeding program often falls substantially behind the expectations, eventually indicating a genotype by environment interaction (Phung 2009).

In many tropical regions, including Ethiopia, the major constraint to smallholder dairy cattle production is the scarcity and poor quality of on-farm feed resources, especially during the dry season; besides their high prices, purchased concentrates have the disadvantage of an uncertain supply (Nyambati et al 2003; Tilahun et al 2005; Belete et al 2009; Azage et al 2010;  Mendieta-Aracia et al 2011). As a result, reduction of milk yield and weight losses of animals during the dry season are common features, which culminate in substantial economic losses to the farmers and also contribute to a low per capita milk consumption. The main reasons for feed shortage in Ethiopia are the reduced in availability of grazing lands as a result of the expansion of arable land for crop production, a very low contribution of improved forages to the nutritional basis and high prices of concentrates and certain agro-industrial by-products (CSA 2008; Asaminew and Eyassu 2009; Teshome 2009). On the other hand, large amounts of molasses as a by-product of sugar processing have been produced by 4 sugar factories in Ethiopia. After promotion by the government, a part of the molasses is used for ethanol production. However, so far this applies mainly to molasses produced in one of the four large sugar processing plants, Fincha Sugar Industry (Ethiopian Sugar Corporation, personal communication). For the near future, the supply of molasses is expected to further increase due to the expansion of the existing factories and a number of new plants currently under construction and in their planning phase (Adugna 2007; GTP 2010).

The roughages, including pasture and crop residues which are important feed resources throughout the country, are low in their nutrient contents and need supplementation with easily available nutrients, mainly carbohydrates and nitrogen compounds (Seyoum and Feyissa 2006). Addressing this problem, Urea Molasses Multi-Nutrient Blocks (UMMB) were used as a livestock feed supplement in a number of countries and several studies showed positive effects on productive and reproductive performance plus an attractive benefit-cost ratio for both local and crossbred dairy cows (Sudhaker et al 2002; Misra et al 2006; Sahoo et al 2009). If UMMB are to be used as dietary supplements, it should be kept in mind that the response of dairy cows to an increased nutrient supply depends on several factors, such as the cows' genetic potential, stage of lactation and the related feeding level, feed quality and climate (Wiktorsson 1979). In addition, breeds which were developed in distinctly different environments may not perform similarly in other settings, particularly under different feeding regimes, indicating a genotype by environment interaction. Therefore, this study was conducted to test the hypothesis that cows of two different breeds (Fogera, a local Ethiopian dairy breed and F₁-Fogera * Holstein Friesian crosses) differ in terms of productive and economic performance, regardless of UMMB supplementation in their mid stage of lactation. Furthermore, the hypothesis is tested that, for both breeds, UMMB supplementation improves the performance traits mentioned above.  

Materials and methods

Design of the experiments 

This study was conducted using a nested design on sixteen mid lactating dairy cows of each breed (local Fogera and Fogera * Holstein Friesian crossbred, F₁). In the beginning of the experiment, the majority of the cows were in their mid stage of lactation and the selected cows were on the average 76 days in lactation. Cows from each breed were divided into two groups of 8 cows each and were fed either a control diet consisting of forage and concentrate or the control diet plus UMMB as a supplement. Cows were in their second and third lactation. The studies were carried out at Andassa Livestock Research Center (ALRC), Amhara Region, Ethiopia. ALRC is located at 11⁰29´N latitude, 37⁰29´ E longitude, at an altitude of 1730 meter above sea level. The annual average rainfall at the center is 1150 mm and the mean minimum and maximum temperatures during the experiments were 9 and 34⁰C, respectively. The four treatments used for the experiment were Fogera cows fed the traditional diet as a control (FN), Fogera cows fed the control diet plus UMMB as experimental group (FS), crossbred cows fed the control diet (CN) and crossbred cows fed the control diet plus UMMB as experimental group (CS).

This feeding trial was carried out between December 2010 and February 2011, including a 4 weeks adaptation period. Cows of each breed were selected based on their days in milk, number of lactation, initial milk yield, body condition score (≥ 1.5) and health status. From each breed 16 relatively uniform cows were equally divided into two groups and assigned to the control and UMMB supplemented group. The daily dietary energy and protein supply for both breeds were planned to be 57 and 64 MJ ME with 615 and 879 g crude protein for the control (FN, CN) and UMMB supplemented groups (FS, CS), respectively. The nutrient requirements for non pregnant lactating dairy cows of 300 kg live weight which produce 4 l of milk with 4 % fat (Moran 2005) were the basis for defining the control diet. This performance level is similar to the average dry season daily milk production performance of crossbred cows in Ethiopia (RHHSEBS 1998; ELDMPS 2007). UMMB supplementation of the control diet was planned to result in 12 and 43 % higher energy and protein supply, respectively.  

Cow management and feeding 

Cows were housed individually in a well-ventilated, open barn in tie-stall pens with concrete floor. Prior to the experiment, cows were treated for internal and external parasites and were vaccinated for Anthrax and Bovine Pasteurellosis. Postpartum oestrus activity was monitored daily by a researcher, veterinarian, herd attendants and with the help of a teaser bull. Before milking, calves were allowed to suckle for about 1 minute to initiate milk ejection and again after milking. Cows were milked twice daily by hand and milk offtake was recorded at each milking period.

The daily basal diets consisted of baled hay (ad libitum), freshly harvested Napier grass (4 kg/cow), and 1.5 kg of home made dairy concentrate/cow (74 % wheat bran, 25 % nug (Guizotia abyssinica) seed cake, 1 % common salt). One bale of hay, weighing between 18 and 25 kg, was offered to an individual cow and was consumed over a period of 3 to 4 days. The daily hay offer depended on the consumption level of individual cows. As soon as about 20 % of the previously offered hay was left, additional hay was given from the same bale. Hay was offered throughout day time (6 am to 7 pm). The remains were collected every morning as refusals before additional feed was offered. Samples from the refusals were taken every morning and were pooled for analysis.

The hay consisted of grasses such as Andropogon abyssinicus, Cynodon dactylon, Digitaria abyssinicus and of legumes such as Trifolium quartinianum, Trifolium polystachyu and Indigofera atriceps. Four kg of Napier grass (Pennisetum purpureum) were offered to individual cows at around 10 am. Home made concentrate was offered after morning milking (8 am). The supplemented groups were offered UMMB in addition to the basal diets. Cows were allowed to lick the block between 10 am and 5 pm, after which the blocks were collected. During this time, a cow was assumed to consume about 500-700 g UMMB.

UMMB were formulated from 37 % molasses, 10 % urea, 10 % cement, 25 % wheat bran, 15 % noug seed cake and 3 % common salt (Bediye et al 2009). Using this formula, a 5 kg block was produced by thoroughly mixing the exact quantities of the components. Cement and salt were dissolved in 200 ml of water prior to being added to the other components. The mixture finally had a dough texture and was put into a plastic sheet lined, rectangular wooden frame of 30*20*20 cm depth, length and width, respectively, for molding. Compaction was applied using a wooden bar; afterwards the block was left for 15 minutes until it maintained a proper shape. Finally, it was removed from the frame and left to dry in a well ventilated room for about 72 hours, after which it was ready for feeding. Cows had access to fresh water from the nearby river two times per day. 

Data recording 

After the adaptation period, data were collected for daily milk offtake, intake of all feedstuffs pooled over a one week period. Representative individual milk samples of 25 ml were taken in triplicates every two weeks for a rapid analysis of milk composition using a Lactoscan milk analyzer (Milkotronic Ltd, Nova Zagora Bulgaria[1]).

Body weight was estimated from heart girth measurement on the cows every two weeks by using the regression formula developed at ALRC (Addisu 2010):

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

At the same time, Body Condition Scores (BCS) were estimated by two independent observers and the mean was recorded as the body condition of the cows. Body condition estimation was done according to the procedure designed by Rodenburg (2000), using a scale from 1 (very thin) to 5 points (over conditioned) which combined both visual and tactile appraisals. No heat was observed during this experiment as was the case for any unforeseen events. Protein and energy conversion ratios were calculated using protein and energy intake over milk protein and energy offtake. Offtake of Energy Corrected Milk (ECM) was calculated using the formula by Tyrrell and Reid (1965, equ.2):

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

 Milk energy offtake was calculated based on an equation published by Tyrrell and Reid (1965, equ. 1):

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

Where, MEO = Milk energy offtake (MJ/d) and units for fat, protein and lactose in milk are g/kg and milk offtake is in kg/d.

Nutrient analysis for all feed components and refusals were made by taking representative samples from each feedstuffs and employing the standard method of Near-Infrared Spectroscopy (NIRS) as used in the feed laboratory at Holetta Agricultural Research Centre (Fekadu et al 2010). The Metabolizable Energy (ME) content of each feedstuff was estimated, using a formula published by MAFF (1984):

ME (MJ kg^-1 DM) = DOMD * 0.015                                                                                         

Where, DOMD = Digestible Organic Matter in Dry Matter (g kg^-1DM)

 Results from feed analysis (Table 1) were used to calculate the Organic Matter, Neutral Detergent Fiber (NDF) and Acid Detergent Fiber (ADF) intake which are presented in Table 2. Data on feed costs and price of milk were collected for partial budgeting. Prevailing market prices for feed ingredients and milk during the experimental period were used to calculate net return/cow/day, net return/l of milk, feed costs/l of milk and benefit-cost ratios. Net return/cow/day was calculated as the difference of daily milk sold per cow minus daily feed costs per cow. Feed costs/l of milk was calculated using feed costs per day divided by milk offtake/day. The benefit-cost ratio was calculated from change in net return between the control and supplemented diet during the experiment divided by change in feed costs.

Statistical analysis 

Data for milk offtake, milk composition, feed and nutrient intake, milk energy offtake, energy and protein conversion ratio, net return/cow/day, net return/l of milk, feed costs/l of milk, estimated body weight gain, BCS, OM, NDF and ADF were analyzed using the Mixed Linear Model procedure of SAS (2009). Treatment was included in the model as independent variable, days in milk, estimated initial body weight as co-variables. Tukey-Kramer test was used to separate least square means. Significance was defined as P < 0.05 unless stated otherwise. The statistical model used for data analysis was:

Y_ijk = µ + α_i + β_j(i) + X + ε_ijk

Where

Y_ijk = milk offtake, milk constituents, feed and nutrient intake and conversion, daily gain, BCS, cost and return, OM, NDF and ADF intake

 µ = overall mean

 α_i = fixed effect of i^th treatment (i = FN, FS, CN, CS)

β _{j(i) =} random effect of j^th cow within i^th treatment

X = days in milk and estimated initial body weight as co-variables

ε_ijk = experimental error

Benefit-cost ratios were subjected to descriptive statistics. 

Results and discussion

Milk production, feed intake and nutrient conversion of cows of different breeds 

Data for daily milk offtake and selected parameters of milk quality are presented in Table 2.

The saleable milk offtake of cows receiving the UMMB supplementation was significantly increased by 24 % and 34 % for Fogera and crossbred dairy cows, respectively. In agreement to this, a substantial increment in daily saleable milk offtake as a result of UMMB supplementation was also reported for Buffalo and crossbred cows (Uddin et al 2002 and Alam et al 2006, respectively). In addition, UMMB supplementation also significantly increased the milk fat content by 12 % and 7 % in Fogera and crossbred dairy cows, respectively. The lower increase in milk offtake for local Fogera cows may be due to the fact that this breed has not been predominantly selected for milk yield for decades. This result is in agreement with the study conducted on indigenous and crossbred dairy cows (Nyoni et al 2001).

As suggested from previous studies (Preston and Leng 1987; Leng et al 1991; Sudhaker et al 2002; Upreti et al 2010), the rather well balanced fermentable nitrogen and energy content of UMMB supports the microbial activity and thereby contributes to an increased fiber digestibility, which is in turn associated with high ruminal acetic acid fermentation and increased milk fat formation. However, supplementation did not seem to have an effect (P > 0.05) on the protein content of milk and only breed-related differences were observed for this trait (Table 2). This is in agreement with results from other authors (Bui Xuan An et al 1993; Plaizier et al 1999; Akter et al 2004; Misra et al 2006; Khan et al 2007) who reported that UMMB or concentrate supplementation had no effect on milk protein content of dairy cows. In contrast to these findings, the milk protein content was significantly improved when local cows were supplemented with UMMB under on-farm conditions in India (Sahoo et al 2009). Even though FS cows were superior to CS cows in milk constituents, because of the higher milk offtake from the latter, the milk energy offtake (MJ/day) was much higher for the crossbred than the Fogera cows (Table 2).

Similar to milk offtake and milk fat traits, UMMB supplementation had a significant (P = 0.03) effect on estimated body weight gain irrespective of breed (Table 2). As a result, a 121 % and 97 % improvement in estimated body weight gain was observed for Fogera and crossbred cows, respectively. In agreement with the present findings, there is evidence to indicate that UMMB supplementation has a significant effect on daily body weight gain, both in crossbred cows (Alam et al 2006) and local cows (Ghosh et al 1993; Alam et al 2009); similar effects were observed in other ruminant species, in Lohi ewes (Rafiq et al 2007) and Buffalo cows (Nimal et al 2007). This is also in line with the significant (P = 0.01) positive impact of UMMB supplementation on BCS: supplemented Fogera and crossbred cows had a 17 % and 9 % greater BCS, respectively, as compared to the control cows.

Even though body weight gains were estimates from changes in heart girth, values seem to indicate that Fogera cows may partition the nutrients supplemented via UMMB with a greater priority into body substance and milk constituent traits, while in the crossbred cows milk output seemed to be prioritized. When studying the response of Holstein Friesian (HF) and Norwegian dairy cows to high and low levels of dietary concentrates, Yan et al (2006) also reported that HF cows had a consistently lower body weight gain and body condition score, but a higher milk energy output than Norwegian cows when supplemented with similar concentrate levels. The authors mainly attribute this to the ability of HF cows to partition more energy into milk and less into body tissue.

In addition to improvements in productive traits, UMMB supplementation also significantly improved the total dry matter intake of cows in both breeds (Table 2). This may be due to the positive effects of UMMB as a source of soluble nitrogen and easily fermentable carbohydrates which probably increased the activity of cellulolytic rumen microflora, hence the fermentation of roughages and concomitantly their intake (Leng et al 1991; Sudhaker et al 2002). It is known that increasing the concentrate level in ruminant diets will increase dry matter intake as a result of proliferation in microflora population (Santra and Karim 2009). Consumption of low quality forage may be particularly improved by UMMB supplementation causing an increase in the activity of cellulolytic rumen microflora (Van Soest 1994), as has been shown for the intake of maize stover in goats (Faftine and Zanetti 2010). In mid-lactation FS cows, UMMB supplementation contributed 6.5 % and 14 % to the overall ME and CP intake per day and cow. The corresponding values for CS cows were 7.6 % and 16.4 %, respectively (Table 2).

Crossbred cows ingested about 0.8 kg significantly more dry matter than Fogera cows, regardless of their dietary treatment. This is probably due to their higher genetic potential for milk production, which increases their nutrient and energy requirement beyond that of the lower yielding Fogera cows. As opposed to the significant increase in total dry matter and organic matter intake due to UMMB supplementation, NDF intake was not significantly different between supplemented and unsupplemented cows of the same breed: The increase in hay intake as a consequence of UMMB supplementation was obviously not high enough to result in a significant increase in NDF (Table 2).

As a result of supplementation, cows of both breeds consumed significantly (P ≤ 0.05) more protein and energy as compared to the unsupplemented groups. A 22 % and 25 % increase in protein intake was observed in FS and CS, respectively, while the two breeds were very similar in terms of the increase in energy intake (13 %). In converting feed energy and protein into milk energy and protein available for human consumption, the crossbreds were more effective than the Fogera cows, but no significant supplementation effect was observed for these traits. On a short-term basis, the efficiency of nutrient use for milk production is primarily dependent on the milk production level of the cows (Chilliard 1989). The results presented herein follow this pattern: ECM offtake was on average 95 % greater in crossbred cows, which only consumed 9 % more energy as compared to Fogera.   

Benefit- cost analysis of UMMB supplementation in mid-lactation cows 

The UMMB supplementation practiced herein proved to be economically beneficial (Table 3). Taking into account milk production and feed costs alone, the relative average improvement in net return per day as a result of supplementation with UMMB was very similar for Fogera and crossbred dairy cows (43 % and 44 %, respectively). However, the supplementation effect was not statistically significant for the Fogera cows (Table 3). In absolute numbers, financial gains resulting from supplementation were greater for crossbred dairy cows than for their Fogera counterparts, resulting in a three times greater benefit-cost ratio for the F * HF cows (1.21 versus 3.66). Uddin et al (2002) also reported that buffalo cows which were supplemented with urea-molasses had a greater net return per day than those of a urea-molasses-concentrate supplemented group. This was attributed to the lower cost of urea-molasses compared to concentrate.

Conclusions

• From this study and from literature sources it is concluded that UMMB supplementation exerts an overall positive effect on forage and feed intake and concomitantly on productive, reproductive and economic performance of dairy cows managed under environmental conditions which are typical for the dry season in Ethiopia. However, crossbred dairy cows perform better in most traits than local Fogera at each of the dietary treatments. Supplementation of dry season diets with UMMB are likely to result in a greater response in milk yield of crossbred cows, but the opposite may occur with regards to milk fat content, while body weight changes are influenced in a similar way for both breeds.

  
  

• Depending on the availability of UMMB for dairy farmers, priority in supplementation should therefore be given to cows with a greater genetic potential for milk production, such as crossbred (local * exotic breeds) cows.

Acknowledgements

The authors would like to express their gratitude to all who have assisted and supported this study, particularly the OEAD-Gmbh (Austrian Agency for International Cooperation in Education and Research) and KEF (Commission for Development Studies) for funding the project and to Alemseged Gebremariam, Head of Land-O-Lakes Amhara Region, for providing the milk analyzer. The contribution of Dr. Azage Tegegne (ILRI, Addis Ababa, Ethiopia) during the planning phase of the experiment deserves great appreciation. The authors would also like to appreciate the valuable comments provided by two anonymous reviewers of this paper.