An on-farm appraisal of feeding urea-treated straw to buffaloes during late pregnancy and lactation in a mixed farming system

K Sharma, Narayan Dutta and Uma Naulia

Centre for Advanced Studies in Animal Nutrition

Indian Veterinary Research Institute

Izatnagar-243122, India
pn@ivri.up.nic.in

Abstract

An on-farm study was carried-out with 48 multiparous buffaloes, maintained under a subsistence-oriented mixed farming system, to assess the effect of feeding 4% urea-treated wheat/rice straw (TS) with a supplement (Parts/100:deoiled soybean cake 10 to12; rice polish 88 to 90) during late pregnancy (about 8 to 10 weeks before calving) and lactation (300 d). The buffaloes were randomly selected to receive either TS (wheat/paddy) or untreated straw (US) ad libitum. The supplement was given at similar rate to both the groups along with mineral mixture and salt.

Strategic feeding of TS during late gestation to buffaloes significantly improved the birth weight of calves and maintained body condition of buffaloes subsequently during lactation. Buffaloes given TS tended to consume more straw as compared to their counterparts fed US. Buffaloes fed TS had a significantly higher lactation yield relative to buffaloes given TS, but there was no difference in milk composition.  The per cent marginal rates of return calculated over additional feed cost at different stages of lactation in the buffaloes fed TS were 181, 248, 259, 300 and 208 during 0-60, 61-120, 121-180, 181-240 and 241-300 days of lactation, respectively.  The additional milk yield from feeding TS was 492.0 litres.

In the opinion of the participating farmers, strategic feeding of TS significantly improved straw consumption, milk yield, body condition of the animals and the level of cash benefits under a subsistence-oriented mixed farming system.

Key words: Farmers' perceptions, lactating buffaloes, milk yield, socio-economics, urea-treated straw

Introduction

The use of cereal straw for ruminant feeding is essentially constrained by its low voluntary intake and digestibility. Since feeding these low protein roughages on their own results in considerable production losses, much effort has been directed to up-grading them through treatment with either urea or ammonia solutions (Dolberg 1992). Untreated straws having 3 to 4% crude protein initially could be improved to have potential crude protein levels of 7 to 9 % after treatment, which is normally considered the minimum necessary in the diet for adequate intake, digestive activity of microorganisms and maintenance of live weight (Chriyaa et al 1997). Though use of a cheap source of nitrogen such as urea to improve the nitrogen makes it a technically feasible method to improve the nutritive value of straw, its application in the field has been very limited in India. Various factors contributed to the lack of impact, most notably the difficulty by farmers to carry out the technical job unaided and the extra work of treatment, plus the lack of demonstration of satisfactory cost: benefit ratio of using urea-treated straw during the entire production cycle of the animals (Devendra 1997).

Therefore, importance is attached increasingly for on-farm testing, demonstration and refinement of this technique within the resource constraints of the farmers. The approach allows identifying the critical points of intervention necessary to make the technology sufficiently attractive for integration into sustainable year-round feeding systems. Keeping this in view, an on-farm trial was conducted to intensify testing of a simplified low cost procedure of urea treatment for improving utilization of cereal (wheat/rice) straw by buffaloes during late pregnancy and lactation under smallholders' mixed farming system. Some of the critical interventions necessary to make the technology adaptable to the needs of resource poor farmers were identified and benefits associated with increased milk production and farm income were calculated

Materials and Methods

Experimental site

The location chosen for the on-farm investigation, the Bareilly district of Uttar Pradesh province, is located at 170 m above sea level (28^o 22` latitude north and 79<sup>o</sup> 24` longitude east) in the Northern upper Gangetic Plain of India, having an annual rainfall of 900-1200 mm. It is the region of the deepest soil in India, with hardly any variation in relief. This area constitutes the wheat and the rice bowls of India and is suitable for growing various types of subtropical crops. Wheat and rice being the main cultivated crops, their straws form the basal diet of ruminants in the area and are fed during the period April-October and November-March, respectively. Milk production in the region is characterized by low yielding buffaloes and cows, small-scale producers with little land holdings, use of cereal straws with meager amount of green forages, and wheat bran, rice polish and oil cakes as feed supplement. The quantity of supplement given to the animals is usually determined by its availability, work load involved in its collection, cost (cash-outlays) and distance from home -- and not by nutritional importance.

Animals, straw treatment and diet

A set of 42 farm families, collectively owning 48 buffaloes, were selected from June, 2000 for the on-farm trial based on their willingness to participate and ownership of at least one multiparous buffalo in late pregnancy (about 6-8 weeks before calving). The buffaloes were randomly selected to receive either urea-treated straw (TS; wheat/paddy) or untreated straw (US). A simplified procedure using on-farm available materials was used for urea treatment of thresher chaffed straw of wheat (1-4 cm particle length) or manually chaffed rice straw (5-10 cm), depending on their seasonal availability with the participating farmers. Air dried straw was treated at the rate of 50 litres of a 8% urea solution (80 g fertilizer grade urea/litre water) per 100 kg of straw. Barrels cut in half and even smaller capacity utensils (plastic or galvanized iron buckets) commonly found on the farm were used for measuring water and urea and the preparation of the water- urea solution. Small containers (mug, jugs etc) were used to distribute the solution evenly over the straw layers. TS was stacked preferably utilizing corner locations in the household, compressed manually and covered with empty plastic urea sacks for adequate fermentation for a minimum period of one week before feeding it to buffaloes. Choosing a corner location permitted the use of two walls to reduce needs of covering material (O'Donovan et al 1997). The number of animals determined the stack size. It was estimated that 1 cubic meter of chopped compressed straw weighs between 80 and 100kg and is sufficient to feed a buffalo (450-500 kg live weight) for one week. The stack of treated straw was opened after a minimum of 7 days, except during winter (December-February; ambient temp> 20⁰C) necessitating prolonged treatment time of about 2 weeks (Schiere and Ibrahim 1989). The treatment and feeding were synchronized in such a way that animals continued to get urea treated straw without any interruption during the entire period of experiment. The buffaloes usually took 3-5 days initially to become accustomed to the treated straw.

The straw component of the diet was offered 2-3 times a day to ensure at least some refusals (5-10% of straw offered) next morning. A farmers' formulated supplement (Parts/100: deoiled soybean cake 10-12; rice polish 88-90) was used in both the groups. Farmers usually purchase oil cakes (mustard, rapeseed, linseed, soybean) from local expellers that vary in quality and cost depending on the source. Therefore, deoiled soybean cake was given to participating farmers from the project to maintain uniformity during the course of this investigation. Each buffalo was given 1.5 kg supplement in the morning during late gestation. The amount of supplement fed to each buffalo during lactation was adjusted weekly at the rate of 50% of the average daily milk production as per farmers' normal practice (Ranjhan 1987). A mineral mixture and salt (30g each) was provided to all the buffaloes irrespective of dietary treatment to avoid a compensatory intake effect of urea-treated straw on mineral deficient animals. Participating farmers were advised to feed 1-2 kg green foliage or leaves daily to avert vitamin A deficiency.

Sampling and analyses

The feeding trial was initiated at about 6-8 weeks before expected parturition and continued for 10 months after calving (300 d of lactation) during which monitoring was done for feed intake, milk production, milk composition and general health of the animals. The researchers, in consultation with the farmers, measured feed intake of each buffalo twice a week, which were averaged to calculate mean daily feed intake during lactation. Newborn buffalo calves were weighed by a spring balance within 3 days of their birth;  the body weight of buffaloes was estimated indirectly by measurement of heart girth at monthly intervals. Participating farmers kept daily records of milk yield (two milkings /day). Milk samples were drawn at fortnightly intervals and brought to the laboratory for further analysis.

Samples of the feeds obtained throughout the experimental period were bulked, mixed and ground before being analysed to determine DM by the oven drying method, organic matter by muffle furnace incineration, crude protein (CP) by Kjeldahl method (N x 6.25), ether extract and total ash (AOAC 1995). Neutral detergent fiber (NDF) and acid detergent fiber (ADF) were determined by the method of Van Soest et al. (1991). NDF was assayed with sodium sulfite in the NDF reagent without a-amylase and the results were expressed with residual ash. Milk samples collected at fortnightly intervals were analysed for fat, total solids, solids-not-fat (SNF), CP and ash (ISI 1961). The data obtained from the experiment, related to feed intake and milk production during lactation, were used to analyze a partial budget for a milk production system relying on TS as basal feed (Stemmer et al 1998). The results obtained were subjected to analysis of variance in a completely randomized design and the significance of the differences between treatment means was determined using the student t-test (Snedecor and Cochran 1989).

Results and discussion

Chemical composition of feeds

 The urea treatment of straw increased water content to around 28-35 per cent and caused an intensive ammonia smell at the time the stacks were opened after a week in summer and two weeks in winter. Various studies on the storage of urea-treated straw have shown that it is essentially the moisture content that determines the decomposition effect (Schmidt and Weiβbach 1990). At least 20% water content and 7 days storage may be quite sufficient in tropical climate (Ghebrehiwet et al 1988; Schiere and Ibrahim 1989; Dass 2000) to achieve favorable rate of hydrolysis of urea to ammonia and DM degradation rates (Bergner et al 1997).

Ammoniation of wheat /rice straw almost doubled the crude protein content from 3.9-4.1 to 8.1-8.5% (Table 1) due to retention of ammonia nitrogen (Dias-da-Silva and Sundstol 1986; Zorrila-Rios et al 1991; Chauhan et al 2000). A slight reduction in the cell wall (NDF/ADF) content observed in urea-treated wheat or rice straw is consistent with earlier reports (Lamba et al 2002).

The quality of the straw treated by this simplified method was considered to be as good as achieved through the use of plastic sheet of 0.1-0.2mm thickness (O'Donovan et al 1997). The CP content of farmers' formulated supplement was lower than the 20% CP usually recommended in concentrate mixtures for lactating buffaloes given predominantly straw-based basal feeds (Arora 1988).

Performance of buffaloes

Initiation of strategic feeding of TS to buffaloes during late pregnancy significantly increased the birth weight of their calves (Table 2). Since relative fluctuation in voluntary intake of FFS was meager between the treatment groups, the variation observed in birth weight of calves indicated that the buffaloes on TS responded to better dietary availability and utilization of energy and protein.

Feeding of TS during lactation significantly improved total dry-matter intake. The intake of the supplement was comparable irrespective of dietary treatment; however, the buffaloes given TS consumed 24% more straw as compared to their counterparts in the US group. Nevertheless, the average daily DM intake in both the groups was lower than the 3% of body weight recommended for lactating buffaloes fed on roughage and concentrate in varying proportions (Kearl 1982; Ranjhan 1998). Improvement of straw intake after urea treatment has been well established and may vary widely depending on straw quality and treatment conditions (Dass 2000; Lamba et al 2002). It has been observed that forage intake drops significantly when animals are fed forages with CP levels below 7% in DM  (Chriyaa et al 1997), which was the case for the US diet in our experiment. All the buffaloes conceived within 4 month of calving irrespective of dietary treatment except for seven animals (3 in TS and 4 in US) that were reported to be in the habit of conceiving once in two years.

Milk yield and composition

The buffaloes fed TS produced 57% more milk than those fed US (Table 2; Figure 1), without any apparent loss in body condition. The observed results confirm the earlier reports that indicated an extra yield of 0.5-1.5 kg milk and/ or saving of 20-30% concentrate with a reduction of feed wastage of 20-30% (Singh et al 1993; Singh and Prasad 2002).

Figure 1. Effect of feeding treated (TS) or untreated (US) straw on milk production by buffaloes

The observed similarity in milk composition in buffaloes irrespective of the straw treatment (Table 3) is in agreement with earlier reports (Chauhan et al 2000; Lamba et al 2002) and indicates that milk quality was not reduced or affected by feeding TS.

Partial budget analysis

A partial budget analysis (Table 4)  implies that only variable costs change while fixed costs do not (Stemmer et al 1998). The net benefit (ΔNB) is the difference between change in returns (Δ R) and change in variable cost (Δ C), or ΔNB= ΔR- Δ C. If the net benefit is positive, the new technology under consideration will provide higher income to the farmer. However, in the case where financial resources are limited, higher benefits will not be attractive if they require much higher cost. Therefore, the increase in costs has to be considered in relation to net benefits. This was done by calculating the marginal rate of return, that is MRR= ΔNB / Δ C (Table 4).

The changes in costs and returns of a milking buffalo feeding system with TS in comparison to US were examined based on a 300 days' lactation. It was assumed that there is adequate market for buffalo milk at Rs.10.0/litre (US$ 1.0=Rs.47.0) close to the farm. The additional costs involved were the cost of urea treatment of straw (cost of urea: Rs.4000/tonne and labour: Rs.140.0/ tonne straw treatment) and additional basal feeds due to better intake of TS by buffaloes. The additional return is likely to come from sale of milk ignoring the milk diverted for calves. Based on current market rate, one tonne each of TS, US and FFS could be procured or formulated for Rs.1000.0, 700.0 and 4000.0, respectively. The partial budget analysis of additional feed cost involved in the TS feeding system and additional return in the form of milk during lactation indicate a possible per cent MRR of 249, which appears to be lucrative and identical to the percent rate of net return over feed cost (241) in the traditional system (US) of feeding (Table 4). High returns are required from any farm innovations to offset the risks associated with its adoption. Donaldson (1991) reported from World Bank experiences that increased earnings of 200% are needed to assure that small holders will adopt a new technology package. In the present intervention, the returns may still be higher if likely positive long-term impact of feeding TS on general body condition of buffaloes and their calves is also taken into account.

Farmers' perceptions

At meetings held during and after the conclusion of the experiment to explain and discuss the results, the participating farmers indicated  that the enhanced straw consumption and milk production from the buffaloes fed on TS was most noticeable. They perceived the technology to bring about improvement in general health and birth weight of calves. Almost all the participating farmers (~90%) expressed their willingness to adopt the urea treatment of straw in future if milk could be sold at an assured rate of Rs.10.0/litre throughout the year and concentrate ingredients were available in the local market within 1 to 2 km of their households. Feeding concentrate supplements with varying proportions of locally available ingredients to lactating animals is an accepted practice among the farmers, the formulations changing with the seasonal availability, market price and the financial position of the farmer at the time (Sharma et al 2003). In situations, however, where concentrate is either sold at higher rate or where there is no assured market for milk, the farmers perceived no advantage in feeding TS. This issue is further complicated by the fact that marginal farmers often have to balance the use of scarce cash for animal feeding against its use in the family or crop production in the absence of warranted credit facilities. Farmers reported change in consistency and dark brown colour of dung after introducing feeding of treated rice straw though no negative effects were associated with this phenomenon. The stickiness of dung on treated rice straw could be reduced substantially by feeding a mix of treated rice and wheat straw to animals. Though farmers perceived the procedure of urea treatment as risky and difficult initially due to ignorance, however, it was neither difficult to solve nor to prevent the difficulties and practical problems associated with use and preparation of treated straw by consistent discussion and demonstration.

Conclusions

• Substantial increase in productivity of  buffaloes is possible under subsistence oriented production system through strategic feeding of urea treated cereal straws
  
  
• Promotion of effective infrastructure for technology transfer, further refinement of urea treatment technique and ensuring either on-farm or nearby availability of supplies necessary for treatment are important elements for ensuring impact of the technology
  
  
• Urea treated straw was found be an economically viable and practical feed for buffaloes during late gestation and lactation at farmers' homesteads in a mixed farming system.

Acknowledgement

This study was financially supported by funds provided by the Indian Council of Agricultural Research (AP-Cessfund), NewDelhi, India.

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Received 2 June 2004; Accepted 31 October 2004

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