Cratylia (Cratylia argentea) is a palatable forage readily consumed by cattle. However, immature forage intake is low in sheep (Göhl, 1982). With its high nutritional value, high CP and low tannin contents, cratylia is suitable for ruminant supplementation during the dry season (Andersson et al., 2007). It was considered a reliable resource for silvopastoral systems during periods of scarcity in Mexico and in the Southern State of Anzoategui in Colombia (Valles-De la Mora et al., 2014; Rodriguez et al., 2002).
Palatability and digestibility
There is no mention of limited palatability in the literature. In vitro experiments reported enhanced ruminal fermentation when cratylia was combined with tanniferous shrub legumes and low quality grasses (Stürm et al., 2007).
Cratylia in vitro effect on rumen fermentation resulted from an increased provision of fermentable nitrogenous compounds (Hess et al., 2006). The addition of cratylia to Brachiaria dictyoneura in experiments with RUSITEC also increased the release of methane by 3-4 times (compared to forage alone) and resulted in a further higher nutrient degradation and higher rumen ammonia concentration (Hess et al., 2003).
The IVDMD of different varieties of cratylia assessed in Colombia, has ranged from 589-690 g/kg, the crude protein content from 184 237 g/kg and NDF and ADF contents from 403-528 g/kg and 240-335 g/kg (Andersson et al., 2006). Varieties CIAT 18674 and CIAT 22406 were identified as being superior to the commercial cultivar in terms of dry matter (DM) production, particularly in the dry season (Andersson et al., 2006).
In the Venezuelan southern Anzoategui State, the average protein content was 18.5%, varying between seasons, like P and Ca levels, contrary to the K and Mg levels, which showed no variation (Rodriguez et al., 2002).
The nutritional value of cratylia is characterised by its high CP content and its low content of total tannins, estimated to be around 18% and 0,78 % respectively in China (Zhou et al., 2011) compared to other tropical leguminous species (Leucaena leucocephala, Flemingia macrophylla, Cajanus cajan, Dendrolobium triangulare, Cassia didymobotrya, Cassia bicapsularis and Acacia farnesiana). The levels of ADF and NDF have varied for the various species between 20.7-48.6% and 21.1-55.3%, while the OMD has ranged from 36.9% to 79.3%.
Also in Kenya, cratylia had high CP and NDF contents of 155 g/kg DM and 479 g/kg DM respectively, and a moderate content of total extractable tannins of 44 mg/g DM (Osuga et al., 2005), compared to ten other browse species (Bauhinia alba, B. variegata, Bridelia micrantha, Calliandra calothyrsus, Carissa edulis, Gliricidia sepium, Lantana camara, Maerua angolensis, Sesbania macrantha and S. sesban). Therefore, the addition of PEG to assess the adverse inhibitory effect of tannin for some shrub species (on rumen microbial fermentation as indicated by the gas production) has been then more effective on the other browse species richer in tannins than Cratylia argentea.
Cratylia would have also high level in most minerals (Tiemann et al., 2009) compared to other shrub legumes, as studied in Venezuela on two tropical soils receiving in rainy or in dry seasons, fertiliser applications with P, K, Ca, Mg and S. Comparison of several varieties of Cratylia argentea in the southern Anzoategui state of Venezuela during 3 years, showed that the average protein content of 18.5% varied between seasons, such as P and Ca levels (Rodriguez et al., 2002). In contrast, the K and Mg levels do not vary between seasons.
Cattle
Dairy cattle
In Nicaragua, DM intake and milk production of dairy cows fed on low quality diet of sorghum-silage ad libitum, increased by the suplementation of cratylia (2-3 kg). Neither milk composition (milk fat, total solids, crude protein) nor organoleptic characteristics (smell, taste and colour) were altered (Sanchez et al., 2006).
In Colombia, restricted grazing of mature and/or young cratylia by dairy cows did not significantly influence the production or composition of milk compared to grazing of Brachiaria decumbens alone. Only variation of urea levels in milk and blood were noticed, probably related to a rebalancing between the ammonium released in the rumen and the energy necessary for microbial synthesis (Aparicio et al., 2002).
In Costa Rica, it has been shown that the form of presentation of cratylia influenced intake (Ibrahim et al., 2001). Fresh foliage mixed with molasses increased the IVDMD by 10%. Intake was 32% higher with foliage wilted alone and 43% higher with foliage mixed with molasses. The addition of cratylia compared to the addition of chicken litter had no effect on milk production. Milk compositions were comparable in both these cases (Ibrahim et al., 2001).
In trials with milking cows, a mix of cratylia and sugarcane used as pasture supplementation resulted in a milk increase of 1.2-2.2 L/cow/day. The increase was positively related to cratylia proportion in the mix. Response to cratylia supplementation was limited when cows of minor production potential were utilised or when the basal grass diet had protein levels above 7%. Supplementation with cratylia silage increased milk production by 0.5-1 L/day (Cook et al., 2005).
Zebu cattle
In Colombia, in growing Zebu and crossbred (Zebu x San Martinero) bulls, supplementation with sugarcane and cratylia gave better weight gains when animals were grazing fertilized signal grass than when they were supplemented in a corral. Grazing animals also gave better results with supplementation than without (Rincon, 2005).
Sheep
There may be some difference in feeding sheep with young or mature cratylia. While wilting or drying mature cratylia did not affect intake when sheep were fed mature cratylia, these conservation processes increased the rate of intake when cratylia was cut at early stages. Sheep consumed more readily cratylia in the dry form than in the fresh one, irrespective of their previous consumption experience and their age.
In Colombia, adult African hair-type sheep fed with low-quality herbaceous hay supplemented with cratylia, increased their OM and CP intake by 21% and 19% respectively, as well as ruminal fluid ammonia N concentrations (Abreu et al., 2004).
By another way, supplementation with S. saponaria increased (P < 0.05) dietary OM intake by 14%, and appears as a beneficial way to improve ruminal VFA profile, microbial efficiency, and duodenal flow of microbial protein. Otherwise few interactions between legume and S. saponaria supplementations were observed. Thus supplementation of S. saponaria fruits is a beneficial way for improving microbial efficiency not only for diets based on grass alone, but also for grass-legume diets.
In Colombia as well, the addition of cratylia to a low quality diet of Brachiaria dictyoneura was assessed in order to dilute tannin levels in the diet of sheep and improve their N utilisation (Fässler et al., 1995). The addition of cratylia resulted in an apparent higher N digestibility, but intake and N retention were not significantly altered. Therefore it is important to consider not only the tannin levels but also the digestibility of the legumes used (Fässler et al., 1995).
