LIVESTOCK is an important component of agriculture sector as it shares a major part of food items and source of livelihood for a large segment of population living in the rural and in its urban vicinities.

This sub-sector contributed nine per cent to total GDP, 35 per cent to agriculture GDP and about 10 per cent to the overall foreign exchange earnings. Cattle and buffalo population, according to the Economic Survey 04, is around 45 million heads.

However, the livestock resources have not been exploited fully and the sector has failed to adopt to the technological developments and is stagnating over the decades. The per unit productivity of animals remain low, while the increase in livestock products follow the increase in their numbers.

Peri-urbanization of dairy farms shifted dairy business from small-scattered farms to big, intensive and modern dairy enterprises around big cities like Karachi, Lahore and Faisalabad. This intensification created a number of problems for farmers such as costly inputs, lack of quality control, poor infrastructure and improper marketing channels.

With the advent of the World Trade Organization, these problems are getting more complex. Feed shortage is one of the major hindrances in the development of dairy industry and its costs about 70-75 per cent of the total expenditures incurred by dairy farms. The deficiency in total digestible nutrients and protein demand and supply for livestock industry is about 40 and 65 per cent, respectively.

As a source of fibre, forage is an integral component of ruminant diet. Ruminants belong to a unique class having a complex multi-compartment stomach and include cattle, buffalo, sheep, goat etc. In Pakistan good quality forage is in short supply.

The dry roughages (cereal straws, stovers, corncobs, sugarcane baggasse etc), available in bulk, are being used to compensate this shortage. However, these roughages contain higher quantities of indigestible fibre and lignin and stay longer in the rumen, lowering the intake and impede the ruminant productivity.

The ruminant productivity can be improved by enhancing the nutritive value of the poor quality crop residues. A number of methods have been tested which include, treatment with urea/ammonia (NH3), alkali (calcium and sodium hydroxide) and organic acids (acetic and formic acid).

The ensilation of straws with urea, fermentable sugars and organic acids and treatment of straws with white-rot fungi are other useful techniques. However, these methods could not gain popularity among farmers because of their residual effects, handling and safety problems.

Buffalo normally retain less than 20 per cent of their dietary nitrogen (N) and more than 80 per cent is excreted either in urine or in feces. As a result of urease activity of fecal microbes, fecal-N fractions are rapidly converted to NH3 that escaped to atmosphere. Escaped NH3 to atmosphere can cause soil acidification and eutrophication (environmental concerns).

The NH3 emission and other social concerns (smell and odor) about cattle manure (CM) can be minimized through its proper recycling into some biological system. Options available for utilization of animal wastes include feed for farm animals, fertilizers, substrate for microbial methane (CH4) production and insect protein synthesis and anaerobic fermentation ponds.

These methods have some limitations. Anaerobic fermentation ponds are wasteful because of disagreeable odors they emit. Low protein yields and problems associated with maintenance of large population of insects and earthworms for inoculation of excreta limit its practical application.

The production of CH4 or single cell protein using animal waste is generally far from being economically viable. With the advent of chemical fertilizers, the animal waste as fertilizer has shown a significant decline in its usage.

The more efficient strategy than use of waste as fertilizer can be to process it directly into animal feed. The manure nutrient contents are 3-10 times more valuable as animal feed than as plant nutrients. The economic value of feeding animal waste ranges from Rs1500—9000 ton dry matter (DM), depending upon the mode of conversion, as compared to Rs200-700 and Rs750-1000 ton DM in case of fertilizer and CH4 production, respectively.

The feeding value of recycled CM has been considered higher for ruminants due to their ability to utilize non-protein-N (NPN), an advantage over simple stomached animals. The ruminants are better equipped (enzymatically) to degrade high levels of nucleic acids present in CM than non-ruminants.

Fermentation of CM with poor quality roughages can not only recycle the nutrients of CM but also improve the nutrient value of roughages. The use of CM as ruminants feed has been reported at several occasions. In these studies, sodium hydroxide, urea and molasses were supplemented to improve the fermentation process.

Urea has been used to improve NPN contents and thereby fermentation of poor quality roughages. Ammonia is rapidly liberated from urea because of urease activity of manure, which mismatched with available carbon skeleton and thus caused nutrient loss during fermentation.

To improve the NPN utilization during fermentation the use of fermentable carbohydrate source was necessary. The best-known fermentable carbohydrate sources are molasses and corn grains.

The scientific evidence regarding the chemical composition and feeding value of urea plus molasses treated wheat straw (WS) fermented with CM is limited in lactating buffaloes.

Three experiments have been planned to study the influence of varying levels of urea and molasses on chemical composition of WS fermented with CM and to examine the effect of fermented WS (FWS) on nutrient intake, digestibility, ruminal characteristics, in situ digestion kinetics, N-utilization, milk yield and its composition in Nili-Ravi buffaloes.

In the first trial, chemical composition of urea-molasses treated WS fermented with CM was studied. Eighteen different types of FWS, using three levels of urea (0, 2 and 4 per cent) and two levels of molasses (2 and 4 per cent) were prepared and stored for three fermentation periods (20, 30 and 40 days). The four per cent urea and four per cent molasses improved the DM, crude and true protein (CP, TP) and NH3 and decreased neutral and acid detergent fibre(NDF, ADF) contents, probably because of synergistic effects of urea and molasses on WS.

Higher pH of FWS with increasing urea level was because of higher NH3. Many workers noted that urea was hydrolyzed by urease, a bacterial enzyme, and NH3 was released that led to increase the N-contents and pH of fermented straws. The four per cent molasses level increased the CP and TP contents of FWS, by furnishing readily available energy source, which matched with carbon skeleton for microbial protein production. Fermentation of WS with CM improved not only the nutritive worth of WS but also utilized the CM, which is a waste.

The four per cent urea, four per cent molasses and 40 days fermentation was best-noted combination to ferment WS with CM. In order to evaluate the dietary effects of FWS, metabolic, in situ digestion kinetics and milk production performance studies were launched on Nili-Ravi buffaloes.

Fermented WS was prepared on mass scale. Four iso-nitrogenous and iso-caloric diets having 0 (FWS0; control), 10 (FWS10), 20 (FWS20) and 30 per cent (FWS30) FWS were formulated. In metabolic study buffalo bulls were fed restricted one per cent of body weight on DM basis) and in milk production study lactating buffaloes were fed ad libitum.

Metabolic study showed that ruminal NH3-N concentration at three, six and nine and 12 hours post-parandial were higher with diets containing FWS than control. It indicated constant release of NH3-N from FWS and results in higher NH3-N. At three and six hours after morning feeding, maximum ruminal pH was observed with FWS20 and FWS30 diets than those of others.

Ruminal pH is the function of ruminal volatile fatty acids (VFA) and NH3-N concentrations. The increased ruminal NH3-N and total VFA concentration has led to increase ruminal pH with FWS containing diets. Ruminal total VFA concentration at 3 hours post-parandial was significantly higher in bulls fed control diet.

It might be because of higher concentrate portion (70 per cent). However at six, nine and 12 hours post-parandial, they were higher with FWS. Urea treatment might change cell wall structure and make more structural carbohydrates available for ruminal microbial fermentation and hence increase the VFA contents at latter hours.

In situ ruminal DM and NDF degradabilities, rates of disappearance and extent of digestion were higher with FWS compared with untreated WS. It was probably because of physicochemical changes that occurred during anaerobic fermentation in the lignocellulosic material.

The ruminal DM and NDF lag time was reduced significantly with FWS. Initiation of microbial digestion varied with cell wall surface structure, wall thickness, and lignification, which may explain the longer lag time for untreated WS. The lack of difference in nutrients intake among buffalo bulls fed varying levels of FWS was because of restricted intake.

These results indicated that fermentation of WS with urea, molasses and CM enhance the nutritive value of WS. Replacement of 30 per cent FWS with concentrate in buffalo diet showed no ill effects on intake, digestibility and metabolism.

In performance trial, nutrient intakes remained unaltered in lactating buffaloes fed varying levels of FWS. This lack of difference may be because all diets had approximately similar NDF and ADF concentrations, which probably have similar passage rate from the alimentary canal.

The NDF and ADF digestibilities were significantly higher with FWS20 and FWS30 diets then others. It might be because of availability of more surface area of cell wall for the working of ruminal microbes with FWS. Milk yield (four per cent fat corrected milk) and composition (percent and yield) and blood and milk urea nitrogen (BUN and MUN) with different diets remained unaltered.

The BUN is a useful index of ruminal NH3-N concentrations at similar dietary CP percentages. There is a positive correlation exist between BUN and MUN. In the present study, all experimental diets have similar concentration of CP that might result in similar ruminal degradability.

In conclusion, urea plus molasses treated WS fermented with CM did not affect the nutrient intake and digestibility, milk yield and its composition, when substituted for concentrate up to 30 per cent DM in lactating buffalo diet.