Mesquite pods are palatable feeds and good sources of energy for ruminants due to their digestible carbohydrate content. They can replace part of the grain content of the diet (Sawal et al., 2004).
In many areas, cattle, sheep and goats browse the pods in the fields, snatching them before they drop or picking up the dry ones from the ground. The animals can also graze the dry grasses of low nutritive value found within the mesquite stand (Silva, 1988a; Pasiecznik et al., 1995). The pods can also be collected and fed to stalled livestock, whole or processed, alone or as part of a ration and fresh or after storage. Processed pods are more digestible and ground pods have a better nutritional value. Processing involves the pounding, grinding or milling of pods, either as a single process producing a whole pod extract, or with some separation of pod parts and further processing of each fraction. Processing usually involves milling of whole pods into a homogeneous, coarse flour, although in some cases exocarp and mesocarp (pulp) are separated from the endocarp and seed (Pasiecznik et al., 2001).
Studies show that cattle rations containing less than 50% Prosopis juliflora pods lead to no adverse effects on consumption, digestibility, nutrient balance and animal health (Pasiecznik et al., 2001). Lower inclusion rates of 15-25% are recommended in sheep and goats. In all ruminants species, inclusion rates higher than 50-60% may cause toxicity problems due to the presence of cytotoxic alkaloids (see Potential constraints above).
Early trials found that Prosopis juliflora pods were highly digestible. Reported values in Peru were 83 and 80% for DM and protein respectively (Azevedo, 1961 cited by Barros et al., 1988). In Brazil, values of 71% (DM), 70% (energy) and 67% (crude protein) were observed in sheep (Barbosa, 1977 cited by Barros et al., 1988).
Rations containing Prosopis pods have been recommended for lactating animals and might increase milk production. No effects on milk flavour were noted at less than 50% pods in the ration, though as a sole feed some taste change has been suggested (Pasiecznik et al., 2001). It was reported in the 1950s that pods were used in concentrate rations for dairy cows at 40-60% inclusion rates in Peru, Chile, Argentina and Uruguay. Another report claimed that pods were commonly used in dairy rations in Hawai, where they replaced concentrates such as cottonseed meal (Silva, 1988a). In Brazil, when Prosopis juliflora pod flour replaced up to 60% of wheat bran, in rations for lactating cows, DM intake, weight gain and milk production increased as the proportion of pod flour increased. The most economic ration was when 60% mesquite pod replaced wheat bran (Nobre, 1981 cited by Silva, 1988a). In Colombia, the use of mesquite pods reduced the post-partum interval and increased the weight of dual-purpose cows (Roncallo, 2002). In India, inclusion of up to 30% pods in the diet maintained milk yield (Talpada et al., 1988).
Beef and growing cattle
In Brazil, total replacement of wheat bran by ground pods was found satisfactory for beef cattle (Silva, 1988a). Several trials in India have shown that the inclusion of Prosopis juliflora pods could sustain cattle growth. Diets containing up to 45% Prosopis juliflora pods (1.5% of body weight) gave acceptable live-weight gains (Shukla et al., 1984). Prosopis juliflora pods could be fed to 9-month cross-bred heifers at up to 20% of the diet (replacing rice polishings) without adverse effects on growth and reproductive performance (Pandya et al., 2005). Similar results were obtained with 20% Prosopis juliflora pods in the diet of growing cross-bred calves (Talpada et al., 2002).
Many trials have found that part of the grains or forage in sheep diets could be efficiently replaced with mesquite pods (Obeidat et al., 2008). In Mexico, Prosopis juliflora pod flour could replace up to 45% of sorghum grain while increasing weight gain and was cost-effective at that substitution rate. 60% substitution had a depressive effect on weight gain (Buzo et al., 1972 cited by Silva, 1988a). In Jordan, feeding fattening Awassi lambs diets containing up to 20% (replacing barley) did not affect growth, nutrient digestibility and carcass and meat characteristics, and was cost effective (Obeidat et al., 2008). A similar study found that nutrient intake, digestibility, growth rate and feed efficiency improved when pods were included at 15-25% (replacing barley and maize grain), but that animal performance decreased when pods were included at 35-45% in the diet (Abdullah et al., 2004). In Brazil, replacement of 30% or 45% of sugarcane molasses by mesquite pods gave the highest weight gains (Barros, 1981 cited by Silva, 1988a).
Grinding and heating had no effect on voluntary intake of mesquite pods fed alone, but ground pods associated with Napier grass (Pennisetum purpureum) were eaten in greater amounts than whole pods (Barbosa, 1977 cited by Silva, 1988a). In North-East Brazil, mesquite pods were found to be a very practical and economical option for feeding sheep in the dry season (Oliveira, 2009). The substitution of Napier grass silage by up to 45% mesquite pods had a positive effect on DM intake, weight gain and economic performance (Almeida et al., 2008).
Prosopis juliflora pods have been tested in arid zone countries to feed goats. In Oman, a diet containing 20% pods improved feed intake, feed conversion and body weight gain without compromising carcass yield or quality. However, intake and gain dropped sharply when pods where included at 30% (Mahgoub et al., 2005b). In the drylands of India, up to 35% mesquite pod flour included in the diet of goats in late lactation maintained weight gain, blood parameters and milk yield (Mathur et al., 2003).
In arid regions of India, Prosopis juliflora pod husks were included at 50% in the concentrate (with colocyinth seed cake (Citrullus colocynthis)) fed to Marwari sheep, without adverse effect on animal health (Mathur et al., 2002).
Foliage of Prosopis juliflora is generally unpalatable, which severely limits its use as fodder. However, animals will browse the foliage during dry seasons or droughts when no other forage sources are available. The palatability in decreasing order is goats (most palatable) > sheep > camels > horses (unpalatable). This unpalatability may be caused by the presence of condensed tannins. It increases with leaf age, low-tannin leaf buds and young leaves being more palatable. Dry, fallen leaves appear to regain some palatability, and livestock, particularly goats, are often seen foraging under tree canopies. Leaves have been mixed with other feeds, as a cheap supplement to decrease feed costs, to maintain intake and live-weight gain (Pasiecznik et al., 2001). In India, incorporation of Prosophis juliflora foliage was possible but reduced intake at levels above 10% of the total feed (Shukla et al., 1984 cited by Pasiecznik et al., 2001).
Several authors have reported in the past that Prosopis juliflora leaves are highly digestible. However, recent in vitro DM digestibility data are in the 56-59% range (Lima, 1994; Pasiecznik et al., 2001).