Mesquite ( Prosopis juliflora ) Pods as a Feed Resource for Livestock-A Review

Mesquite or Vilayati babul (Prosopis juliflora) is a drought resistant, evergreen, spiny tree with drooping branches and a deep laterally spreading root system. It grows in semi-arid and arid tracts of tropical and sub-tropical regions of the world and is spreading because the leaves are unpalatable and animals do not digest its seed. The mesquite has become a major nuisance; cutting or pruning its branches to form a canopy would provide shade for travelers, aid harvesting of pods, as well as make available wood for fuel. An average plant starts fruiting by 3-4 years of age and yields annually 10-50 kg pods/ tree, which can be collected from May-June and September-October. Availability of pods worldwide is estimated to be about 2-4 million metric tonnes. Ripe pods are highly palatable; on dry matter basis they contain 12% crude protein, 15% free sugar, a moderate level of digestible crude protein (7% DCP) with a high level of energy (75% TDN). The pods contain low tannin levels below those toxic to animals. Seeds contain 31-37% protein; pods should be finely ground before feeding to facilitate utilization of the seeds. Mesquite pods could replace costlier feed ingredients such as grain and bran contributing 10-50% of the diet. Phosphorus supplements need to be added when mesquite pod, exceeds 20% of animals’ diet. (Asian-Aust. J. Anim. Sci. 2004. Vol 17, No. 5 : 719-725)


INTRODUCTION
Availability of conventional feed resources is declining as livestock populations increase and grazing land declines with more urbanization to satisfy the increasing human population.Thus it is difficult for livestock owners to feed their stock and sustain production of less productive land.Hence suitable supplements are needed to provide sufficient feed for the animals.Efforts have thus been made to evaluate the availability of supplements and the levels at which they can be safely fed to livestock.
To compensate for lower availability of feed resources for animals, new plant species have been tried to maintain vegetative cover over deserts or land with poor fertility.

Production of pods
Prosopis juliflora bears pods in summer and winter.The pods can be collected in May/June and September/October.Peak pod production occurs at 15-20 years of age.Mesquite starts fruiting at 3-4 years of age; 10 year-old plants may yield up to 90 kg pods annually (Anonymous, 1969), however, annual pod yield ranges up to 100 kg/tree (Gomes, 1961;Jurriaense, 1973;Felker and Waines, 1977;Felker et al., 1984;Shukla et al., 1986).A high yield of 169 kg/tree/year has also been reported (Mendes, 1986).Production of pods from the whole of India has been estimated to be two million tonnes (Punj, 1995) indicating availability of a large feed resource that may be used by feed processing industries for livestock.

37.2
De Valle et al., 1983 34-39 Mendes, 1986 62.9-71.2Escober et al., 1987 30.62 Shukla et al., 1990 33.70 3.75 6.67 52.76 3.11 Chopra and Hooda, 2001 Extract NFE) and 30-40% cotyledon (with 27.4-70.3%CP and 62.9-71.2%NFE) (Escober et al., 1987).After detailed chemical analysis Morangoni and Alli (1988) observed that seeds were richer in CP (35%) as compared to whole pods (10%) but there was no difference in their NFE content.In pods 75% of the sugar is in the form of sucrose and linoleic acid is the predominating unsaturated fatty acid; 75% of total protein is extractable wherein lysine was the predominating amino acid (312 mg/g N) in seeds and pods (438 mg/g N) and methionine was the most limiting amino acid while the concentration of other amino acids viz., valine, leucine, tyrosine and phenylalanine were within limits required for ruminants.Concentration of sulphur containing amino acids is low but the content of other amino acids exceeds those required for non-ruminants (Talpada and Shukla, 1988a).Ca, P, Mg and K were lower than cultivated legumes such as Cymopsis tetragonaloba, Cicer arietinum, Vigna ungiculata, Phaseolus mungo etc. Wide variation in proximate constituents (CP-Crude Protein, EE-Ether Extract, CF-Crude Fibre, NFE-Nitrogen Free Extract, Ash) has been observed (Table 1) in the pods.Reports indicate (Barros and Filho, 1986) that pods have high digestibility coefficients (DM-82.6%;CP-80.1%;NFE-83.2%).Studies in India revealed digestibility coefficients of whole pods to be 34.4, 43.3, 51.3, 82.2 and 70.4 for CP, EE, NFE and OM respectively (Talpada et al., 1987).Total sugar content varied between 13.3-19.9% of DM depending upon tree, season and year; further more sulfur containing amino acids were present in lower amounts but most of the other amino acids exceed the requirements of ruminants (Talpada and Shukla, 1988a).
Protein content and sugar contents varied between 7.3-12.7%and 16.3-41.0%of DM respectively but no correlation was observed between protein and sugar content but the protein content was more stable than the sugar content; however, sugar content decreased with the increase in rainfall (Sharma et al., 1994).
Biochemical studies revealed that protein of pods inhibited trypsin in stoichimetric ratio of 1:1.It had only weak activity against chymotrypsin and did not inhibit human salivary or porcine pancreatic alpha amylase.The complete amino acid sequence of pods consisted of two polypeptide chains i.e. 137 residues of alpha chain and 38 residues of beta chain linked together by a single disulphide bond (Negreiros et al., 1992).
Status of macro and micro minerals in Prosopis juliflora whole pods and seeds evaluated by different researchers has been compiled in Table 2.In whole pods calcium content ranged from 0.32 to 0.60% while the phosphorus ranged from 0.08 to 0.41%.The seeds of mesquite had 0.32 to 0.43% potassium, 0.13% magnesium, and 0.01 to 0.05% sodium.Content of iron, zinc and copper (Table 2) was found to be higher in pods collected during winter than during summer while manganese content was not affected due to season (Talpada et al., 1989a).Mineral content have been found to vary with location (Chopra and Hooda, 2002).It may be inferred that pods contain sufficient amount of Ca, P, Mg, K, Na, Cu, Zn, Fe and Mn required for livestock.

Anti-nutritional factors
Uncontrolled grazing of mesquite pods as the sole source of food showed deleterious effects on cattle (Felker and Waines, 1977).Consumption of green immature pods reduced appetite and caused weight loss, weakness, alopecia, nervous symptoms, diarrhoea, fever, dehydration and death of cattle (Gabar, 1986) and thus only mature pods Whole pod 0.41 0.17 Talpada et al., 1979 Whole pod 0.61 0.20 Anonymous, 1987 Whole pod 0.71 0.08 Talpada et al., 1987 Whole pod 0.44 0.17 should be fed.Cyanide poisoning was observed in cattle grazing seeds of the mesquite tree (Seifert and Beller, 1969) whereas Shukla (1982) did not observe any toxic effect after feeding 5.5 kg sugar cane tops with 3.2 kg mesquite pods per cattle.The pods of the mesquite tree were a major source of food for Native Americans in southern California and on the lower Colorado river (Felker and Waines, 1977).
Pods do not contain cynogenic glycosides and can be safely used as feed for livestock (Mahadevan, 1954).Cyanogenic glycosides were absent in seed, mucilage and cotyledons but alkaloids were detected in whole seed (Escober et al., 1987) but no adverse effects on nutrient digestibility and production have been observed due to them.Tannin contents of seeds and whole pods were found to be 1.9 and 1.5% of DM respectively (Talpada al., 1989b).Makkar et al. (1990) reported that mesquite pods contain low levels of phenols and condensed tannins, the latter being below those needed for harmful effects on animals, again reinforcing their value as an animal feed.

Effect of feeding Mesquite pods on nutrient intake, feed utilization and animal performance
Results of feeding Prosopis juliflora pods and estimated safe feeding levels for different ruminant species and laboratory animals are summarized in Table 3.

Effect of processing of Mesquite pods on feed intake and nutrient digestibility
Crushing and drying of mesquite pods did not influence voluntary intake in ruminants (Barbosa, 1977), grinding pods allow complete utilization (Gabar, 1986).Grinding also ensures the seeds are properly utilized (Mendes, 1986).
Prosopis juliflora pods up to 20% of the diet did not affect feed intake in cattle (Talpada et al., 1983).Feed intake was not affected in cattle fed concentrate mixtures containing 40% mesquite pods on DM basis (Rao and Reddy, 1983).Replacement of sorghum with mesquite pods up to 60% of the diet (% DM basis) did not affect feed intake in sheep (Buzio et al., 1972).
At a level of 10%, feed intake and nutrient digestibility were not affected with diet containing unconventional ingredients (Shukla et al., 1981).Replacement of molasses in sheep and goat diets (Barros and Filho, 1986) and cassava in a concentrate mixture for sheep (Barros et al., 1986) with mesquite pods as energy supplement, did not affect digestibility of dry matter, protein and energy.Pods can be safely fed up to 20% of the dietary intake of cattle without adverse effect on nutrient digestibility (Talpada et al., 1983(Talpada et al., , 2002)).Digestibility coefficients of pods were reported to be 71.1% for DM, 66.8% for CP and 69.8% for gross energy (Barbosa, 1977) indicating the suitability of mesquite pods as partial replacement for costlier grains used conventionally for livestock feeds.Complete replacement of wheat bran with mesquite pods in the ration of bovines did not affect nutrient digestibility (Silva et al., 1986).Nutrient digestibility was not affected in lactating cows when mesquite pods replaced 30% of the conventional ingredients in a concentrate diet (Talpada and Shukla, 1988b).Digestibility of dry matter, crude protein and energy were not affected when mesquite pods constituted up to 30% of the diet of rabbits (Silva et al., 1990).

Effect of mesquite pods on growth and production
Growth of cattle calves continued to be normal even when 20% of conventional feeds were replaced with mesquite pods (Talpada et al., 1982) even with diet containing 30% wheat straw (Talpada et al., 2002).Lower weight gain was observed when 60% of sorghum grain was replaced with mesquite pods in the diet of sheep (Buzio et al., 1972).Growth was not affected up to 50% but it decreased about 30% when mesquite pods accounted for 75% of the concentrate diet of sheep (Sharma, 1997).However, reduction in weight gain, dressing percentage and carcass percentage occurred when goats were fed a diet containing ≥85% of mesquite pods (Ibrahim and Gaili, 1985).
Replacement of 30% of conventional ingredients of the ration with pods for lactating cows did not affect nutritive value of the diet, daily milk yield, fat corrected milk yield, efficiency of conversion of feed dry matter and energy to milk (Talpada and Shukla, 1988c;Talpada and Shukla, 1990).
When mesquite pods were used to gradually replace a maize-soyabean mixture in the diet of finishing pigs, the feed intake gradually decreased as did their back fat thickness and meat: fat ratio in the carcass increased (Pinheira et al., 1993); with these authors suggesting mesquite pods were an unsuitable supplement for pigs.Feed intake, feed conversion efficiency, egg weight and egg production were unaffected when wheat bran was replaced with mesquite pods in the ration of laying hens (Silva, 1986).

Effects on nitrogen, calcium and phosphorus balance
Mesquite pods can represent up to 20% of cattle diets without adverse effects on nitrogen, calcium and phosphorus retention (Shukla et al., 1981;Talpada et al., 1983Talpada et al., , 2002)).These observations also applied to cattle fed concentrate mixtures containing 40% mesquite pods (Rao and Reddy, 1983).Positive nitrogen and calcium balance but negative phosphorus balance occurred when growing calves were fed Prosopis juliflora pods, indicating the need for phosphorus supplementation (Talpada et al., 1979).Negative phosphorus balance was also observed in bullocks when pods represented 45% of their diet (Gujrathi et al., 1982a).Level of nitrogen and phosphorus balances decreased when mesquite pods made up 75% of the concentrate diet of sheep (Sharma, 1997).Replacement of molasses with mesquite pods (Barros and Filho, 1986) and cassava as an energy supplement in a concentrate mixture (Barros et al., 1986), did not affect nitrogen balance in sheep.

Effect on rumen metabolism
Rumen metabolites were not affected in young cattle when mesquite pods comprised up to 20% of DM of their diet, apart from low ammonia nitrogen, indicating its efficient utilization by microbes provided with a higher soluble sugar enabling available nitrogen to be used for microbial growth (Talpada et al., 2002).Supplementation of mesquite pods at 30% of the concentrate diet of cattle had no deleterious effect on rumen metabolites (Talpada and Shukla, 1987).Feeding lambs up to 30% DM of their diet as mesquite pods did not affect rumen metabolites (Ravikala et al., 1993), with a similar effect on bullocks fed up to 45% DM from mesquite pods in their diet (Gujrathi et al., 1982b).Rumen pH and concentration of volatile fatty acids as well as ammonia nitrogen were not affected when pods comprised 75% of concentrate mixtures for sheep (Sharma, 1997).Thus mesquite pods did not affect rumen metabolism adversely when used at moderate levels.

Effects on blood profile
With mesquite pods accounting for 30% of concentrate diet of cattle there was no effect on red cell count, white cell count, hemoglobin, blood glucose, calcium, phosphorus, copper, zinc and iron levels in the blood (Talpada and Shukla, 1988d).These results were confirmed for hemoglobin, blood calcium and phosphorus levels for bullocks fed Prosopis juliflora pods up to 45% DM of their diet (Gujrathi et al., 1982a).

Economics of feeding
Feed costs were unaffected in cattle when rice bran was replaced with mesquite pods up to 20% of the diet (Talpada et al., 2002) whereas, cost of feeding could be reduced up to 50% with mesquite pods providing up to 20% in the maintenance diet of camels (Gaur et al., 1982).Replacement of wheat bran with pods in the concentrate mixture of lambs reduced cost of feeding without adverse effect on growth (Ravikala et al., 1995).Replacement of conventional ingredients such as maize, barley, wheat bran, rice bran etc with mesquite pods to the extent of 30% in the diet of lactating cattle improved profitability in milk production with no effect on milk yield (Talpada and Shukla, 1988c).Feed costs were reduced by 26% when mesquite pods replaced up to 50% of the concentrate diet of sheep, without affecting their growth (Sharma, 1997).These results show mesquite pods could be used as a cheaper natural feed resource for livestock.

Conclusion and future line of work
Prosopis juliflora leaves are unpalatable for most livestock but mature pods (with or without seeds) are highly palatable.Mesquite plants bear pods twice a year yielding 10-50 kg pods/plant annually.The wide distribution of the mesquite plant in tropical and subtropical regions of the world, and its fruit bearing cycle, collection of large quantities of pods from forest areas and roadsides is possible, also providing income for poor people.Ripe pods are attractive to animals as they contain free sugars (15% of DM), which have a sweet taste.The spongy mesocarp and cartilaginous endocarp of pods can block the sieve during grinding, hindering proper crushing of seed.The seed has a high level of protein (31-37%) and energy.Unprocessed seeds pass through animals undigested, so the pods should be finely ground before feeding to maximize utilization.Thus changes to the sieve structure needs to be defined to facilitate proper grinding.Chemical nature of the pods could be exploited as binding agent for preparing pelleted foods due to presence of more than 20% mucilage in the pods.Research is required to prevent insect attack before collection of pods in the field and during storage before feeding.Studies are also needed to evaluate the relationship between pod maturity and toxin content so that the best harvesting time can be defined for farmers and with minimum insect damage.Pods contain high levels of energy (75% TDN) and moderate levels of protein (12% CP, 7% DCP), so they could be used as the sole feed supplement during flushing and early lactation to improve production performance of sheep, goat and cattle.Phosphorus supplements need to be fed when mesquite pods make up more than 20% of the concentrate mixture.Experiments need to be conducted to evaluate the extent of phosphorus supplementation with increased levels of pods in the diet of livestock.The pods could be safely used as a cheaper feed resource by replacing of bran and up to 50% of grain component of diets of cattle and sheep.

Table 1 .
Chemical composition and nutritive value of Prosopis juliflora pods (% of DM)

Table 2 .
Macro and micro mineral content in Prosopis juliflora

Table 3 .
Use of Mesquite pods in the diet and an evaluation of safe feeding level for different animal species CM: concentrate mixture, CP: crude protein, FCR: feed conversion ratio, N: nitrogen, Ca: calcium, P: phosphorus, PER: protein efficiency ratio, NPU: net protein utilization.