Effects of supplementation with rumen fermentable carbohydrate and sources of 'bypass' protein on feed intake, digestibility and N retention in growing goats fed a basal diet of foliage of Tithonia diversifolia

Khamparn Patoummalangsy

Department of Livestock and Fisheries, Faculty of Agriculture
NationalUniversity of Laos, Vientiane Capital, Lao PDR
khamparnp@yahoo.com.au

Table of contents

1. Introduction

2. Objectives

3. General discussion

3.2. The uses of Tithonia diversifolia

3.3. Nutritive value of Tithonia diversifolia

3.4. Constraints to use of Tithonia foliage in ruminants

3.5. Improving the utilization of Tithonia foliage for goats by supplementation

3.5.2. Increasing the supply of bypass (escape) protein

3.5.3. Tree foliages as sources of bypass protein

4. Conclusions

5. Acknowledgement

6. References

1. Introduction

Goats are the dominant small ruminants and rearing them is an integral part of many farming systems in Laos for many years. It is a resource that contributes protein and fat to the human diet and often this enterprise can help farmers to overcome an unforeseen crisis, which demands immediate finance. Domestic goats in Laos generally are kept in herds that wander on hills or other grazing areas. However, the extensive grazing system which is dependent on the availability of natural feed resources can not provide sufficient feed during the dry season (Xaypha, 2005). It has been proposed that one way to counter these adverse effects is by making available the leaves from trees and shrubs (Steele, 1996).

There are many trees, herbs and shrubs in Laos that have potential as a source of high quality feed for goats but for many of these resources, there is little information about them and they are not well utilized (Kongmanila, 2007). More research is needed to assess the opportunities offered by trees and shrubs and the constraints to their utilization. One such shrub, that grows wild in the upland regions of Laos, and about which little is known, is Tithonia diversifolia.

The aim of this thesis was to identify the nutritional constraints to the use of foliage of Tithonia diversifolia as the basal feed of growing goats. Tithonia diversifolia (Helms) is a perennial shrub that grows naturally in many upland regions in Laos, where it is used primarily as a green manure. It has been reported that the foliage of Tithonia is rich in protein (more than 20% in DM) and is highly digestible but that the protein in the leaves is rapidly degraded in the rumen to the extent of 85% in 24 hours (Mahecha and Rosales, 2005). Practical observations in Colombia (Rodríguez Lylian, personal communication) indicated that it could serve as the complete diet of growing goats but that the growth rates were very low.

On the basis of these observations it was hypothesised that the probable constraint to achieving the true nutritive potential of Tithonia for ruminants was an inadequate supply of metabolizable protein.

2. Objectives

It was proposed that two ways to improve goat performance on Tithonia foliage as the main feed would be: to feed easily fermentable carbohydrate, to utilize better the soluble protein in the rumen and to supplement with foliages with known rumen bypass characteristics.

Three experiments were carried out using growing goats housed in metabolism cages so as to study feed intake, apparent digestibility and N retention with different combinations of Tithonia foliage, cassava root chips and tree foliages. In Experiment 1, the basal diet was sun-dried Tithonia foliage and the supplements were cassava root chips and mulberry leaves. In Experiment 2, a comparison was made of sun-dried Tithonia foliage and the fresh foliage with and without cassava chips plus mulberry leaves. In Experiment 3: the basal diet was fresh Tithonia foliage and four different sources of leaves (from banana, Erythrina variegata, mulberry and Jackfruit).

3. General discussion

3.1. Agronomic studies

Tithonia diversifolia, often called Wild sunflower and Mexican sunflower, belongs to the family of Compositae, genus Tithonia and species diversifolia (Henderson, 2001). Tithonia originated from Mexico, and it is now widely distributed throughout the humid and sub-humid tropics in Central and South America, Asia and Africa (Sonke, 1997 cited by Jama et al 2000). In western Kenya, it is renowned as a component of agro-forestry systems as it is rich in N, P and K which are essential for soil fertility. Biomass from Tithonia has proven to be valuable in improving soil fertility for crop production in areas constrained by soil N, P and K deficiencies (Lijzenga, 1998). It has been reported that addition of foliage of Tithonia diversifolia to the cropping area leads to double the yield of the crops and that it is more effective than urea when applied at the same N rate (Jama et al 2000; Sanchez, 2001). It is a perennial shrub that grow 1.5 to 3 m high. The leaves are ovate to triangular from 15 to 30 cm long. The flowers resemble the single dahlia; and are 5 to 8 cm across with bright yellow colour. This plant needs well- drained soil, which is moist to dry; it will tolerate drought. It should be planted 0.5 to 1 m apart in a sunny position according to Anon., (No date). It is said that it is easy to grow by planting cuttings derived from the lower, more fibrous part of the stem (Rios, 2002). It can also be established from seed which is said to have a germination of about 16% when the seeds are collected immediately but that after 4 months storage the germination may reach 90%. Under practical conditions, over 75 % of seeds germinated when the seeds were planted in the field during the rainy season (Muoghalu and Chuba, 2005). However, establishing Tithonia from cuttings is the more usual method employed by farmers (Parada, no date). Planting stakes in plastic bags filled with soil, rice husks and cattle manure in a nursery resulted in a percentage of germination more than 85% (the method employed to establish Tithonia plants for experiments 2 and 3).

Agronomic studies in Colombia indicated a high yield potential when Tithonia was planted from cuttings at distances of 0.75 x 0.5m (26 000 plants/ha); the fresh biomass yield after 110 days was 3 kg per plant, equivalent to 92 tonnes/ha of fresh foliage (Katto and Salazar, 1995). Parada (No date) reported that when Tithonia was planted at spacing of 1.0 x 0.5m, the fresh biomass yield after 75 days was 51 tonnes/ha. When Tithonia was planted on the distance of 1x0.5m, compared with planted distances of 1x1m and 1x0.75. These data show that Tithonia diversifolia is a shrub, that is established easily and grows fast with a very high biomass production.

3.2. The uses of Tithonia diversifolia

According to Jama et al (2000), Tithonia diversifolia is a multi-purpose shrub the foliage from which has many uses:

• as fodder for ruminants (Anette, 1996; Roothaert and Patterson, 1997; Roothaert et al 1997),

• in poultry feeds (Odunsi et al 1996),

• as fuelwood (Ng'inja et al 1998),

• as compost (Drechsel and Reck, 1998; Ng'inja et al 1998),

• to control soil erosion con (Ng'inja et al 1998),

• as building material and shelter for poultry (Otuma et al 1998).

In addition, extracts from Tithonia plant parts reportedly protect crops from termites (Adoyo et al 1997) and contain chemicals that inhibit plant growth (Baruah et al 1994; Tongma et al 1997) and control insects (Carino and Rejestes, 1982; Dutta et al 1993). Extracts of Tithonia are said to have medicinal value for treatment of hepatitis (Lin et al 1993; Kuo and Chen, 1997) and control of amoebic dysentery (Tona et al 1998). Among the various uses of Tithonia, its medicinal value is one that farmers in western Kenya frequently report (Jama et al 2000). The following authors are cited in the paper by Jama et al (2000).

3.3. Nutritive value of Tithonia diversifolia

Olayeni et al (2006) used Tithonia diversifolia leaf meal as 20% of the diet of weaner pigs and reported no reduction in growth rate. Tithonia leaf meal was considered to be a valuable supplement in diets for laying hens and a cheap means of enhancing egg yolk coloration (Odunsi et al 1996). Akinola et al (1999) reported that in south-western Nigeria, T. diversiforia is browsed by nomadic and village cattle, sheep and goats, and that farmers fed the harvested forage to these animals as well as to rabbits. A similar report from Katto and Salazar (1995) described its use as forage for sheep and guinea pigs.

The crude protein (CP) level in the leaves of Tithonia in Colombia was reported to be as high as 28.5% in DM (Katto and Salazar, 1995). Olayeni et al (2006) described the leaf meal as having 18.9% CP, 11.0% crude fibre (CF), 5.5% ether extract (EE) and 13.2 ash. According to Premarante et al (1998) the leaves and petioles of Tithonia are low in lignin and have a DM degradability of 90% in 48 hr. The crude protein in the leaves was also shown to be rapidly degraded in the rumen to the extent of 85% in 24 hours (Mahecha and Rosales, 2005).

There appear to be few reports on the use of Tithonia in feeding trials with ruminants. Wambui et al (2005) used sun-dried Tithonia foliage (leaves and tender shoots) as a supplement for goats fed a basal diet of urea-treated maize stover and maize germ meal. Growth rates were 83 g/day and better than was obtained with supplements of Sesbania and Calliandra foliage. More recently, it was shown that Tithonia foliage could replace 25 to 35% of the concentrate fed to milking cow grazed on pasture, with no effect on both quantity and quality of the milk (Mahecha et al 2007). These findings indicate that Tithonia foliage has potential as a protein supplement to low quality roughages for goats and cattle. However, it is important to note that in both cases the animals also received feeds known to provide bypass protein (maize germ meal in the case of the goats and a commercial concentrate in the case of the cattle). In contrast, when fresh Tithonia foliage was fed as the sole diet of young goats in Colombia, the growth rates were very low but were dramatically improved when 40% of the Tithonia was replaced by mulberry foliage (Rodríguez Lylian, personal communication).

3.4. Constraints to use of Tithonia foliage in ruminants

In Experiment 2 (Paper I), it was observed that when fresh Tithonia foliage was the sole feed of the goats, the apparent digestibility of crude protein was very high (90%), that urine volume was also very high, and that these responses were associated with a high excretion of N in the urine and a correspondingly low N retention. Similar relationships were observed among crude protein apparent digestibility (90%), urine volume and urinary N excretion when the sole feed of goats was water spinach (Ipomea aquatica) (Buntha and Ty, 2006). In a related experiment with water spinach and goats, it was observed that that urinary output increased linearly with degree of replacement of cassava foliage by water spinach (Pathoummalangsy and Preston, 2006). Wambui et al (2006) also recorded high urinary N excretion for the goats supplemented with Tithonia foliage when compared with Calliandra and Sesbania foliages. It appears therefore that there are close similarities between Tithonia and water spinach (ie: high content and digestibility of crude protein, high urine volume and high urinary N excretion and low N retention).

The above considerations, together with the low content of extractable (soluble?) tannins (0.6%) for Tithonia foliage reported by Wambui et al (2006) and the high rumen degradability of the crude protein (Mahecha and Rosales, 2004), all suggest that the protein in Tithonia is highly soluble with poor "bypass" characteristics.

3.5. Improving the utilization of Tithonia foliage for goats by supplementation

Based on the hypothesis that the protein in Tithonia is highly soluble with poor "bypass" characteristics the corrective measures are: (i) to increase the efficiency of utilization of the crude protein at the level of the rumen (ie: increase microbial protein synthesis); and (ii) provide a supplement with known " rumen bypass" characteristics (Preston and Leng, 1987).

3.5.1 Improving rumen microbial production

Carbohydrates are the most important source of energy for rumen microbes, and their behavior in the rumen differs greatly among sources (Leng, 1997). Some of these differences related to structural (cell wall) carbohydrates versus non structural carbohydrates (cell contents) (Tammioga et al 1989). Saldana et al (1989) reported that starch degradability affected utilization of nutrients in the rumen more than protein degradability.

Cassava chips are reported to be excellent sources of rumen fermentable carbohydrate as they are rich (70-80%) in rapidly fermentable starch (Kearl, 1982; Sommart et al 2000; Vearasilp and Mikled, 2001; Gomez and Waldivieso, 1983). Sathapanasiri et al (1990) observed that starch in cassava roots is highly degraded in the rumen (94%). Chanjula et al (2003) found that cassava chips were better than sweet potato roots, maize meal and rice bran, as a means to optimize use of NPN for rumen microbial protein synthesis. Hoover and Stoke (1991) and Khampha and Wannapat (2006) also indicated that the high rate of digestion of carbohydrate in cassava chips was a major factor controlling the energy for growth of the rumen microbes.

The value of using cassava roots chips in diets based on Tihonia foliage was clearly demonstrated in Experiments 1 and 2, where it was shown that supplementing Tithonia foliage with cassava root chips improved the N retention of goats by 50 and 100%, respectively compared with feeding the Tithonia alone.

3.5.2. Increasing the supply of bypass (escape) protein

The relative pathways that are involved in digestion of crude protein are outlined in Figure 1  (Mcdonald et al 2002).

Figure 1. Fate of dietary crude protein in the ruminant animal

The major improvements in productivity of ruminants when they are provided with a source of protein that " bypasses" or " escapes" the rumen fermentation are well documented, and are observed even when the rumen is supplemented with essential nutrients for microbial synthesis (Preston and Leng, 1987).

The sources of bypass protein that have been most researched are the by-products of agro-industrial processing of animal origin (eg: fish and meat meals), and after oil extraction from oilseeds (eg: cottonseed and soybean meal). Only recently has attention being given to leaves from trees and shrubs as potential sources of bypass protein. The advantages of these potential sources of bypass protein are that they can be grown on the farm whereas by-product meals have to be purchased.

3.5.3. Tree foliages as sources of bypass protein

Normally, the factors that facilitate the rumen escape of protein from forages is the presence of low levels of condensed tannins which can form complexes with protein, which are insoluble in the neutral pH in the rumen but which dissociate in the acid conditions of the abomasum (Barry and Manley, 1984). Cassava foliage has been identified as an excellent source of bypass protein when used to supplement liquid diets of molasses-urea (Ffoulkes and Preston 1978) or urea-supplemented rice straw (Tham, 2007; Sath, 2007).

Replacing grass with ensiled leaves of mulberry (Morus alba) promoted linear increases in growth rate of goats (Ba and Ngoan, 2005) while the fresh leaves were comparable to cottonseed for growth of cattle (Cuong et al 2005).

In Experiments1 (Paper I), supplementation of Tithonia hay with fresh leaves of mulberry doubled the N retention of the goats, while in Experiment 3, N retention was three time higher when mulberry leaves rather than banana leaves were fed as supplements to fresh Tithonia foliage.

In a comparison of several tree foliages as the sole diet of growing goats, the best results in N retention (4.1 g/day) and growth rate (78.6 g/day) were with the foliage of Erythrina variegata (Kongmanila, 2007). Linear increases in milk production in goats were reported by Esnaola and Rios (1990) when increasing levels of foliage of Erythrina poeppigiana were given as a supplement to King grass. Jackfruit (Artocarpus heterophyllus) foliage as the main diet of goats supported growth rates of 69 g/day whereas those fed Trichanthera gigantea lost body weight (Keir et al 1997). Jackfruit foliage successfully replaced concentrates in diets for lactating goats in a study by (Mui et al 2001). Leaves from the banana tree were less digestible but supported higher feed intakes in cattle than the banana pseudostem in diets made iso-nitrogenous by addition of urea (Ffoulkes and Preston, 1978). These authors suggested that the higher intakes with the leaves may have been an indication that the proteins in the leaves had rumen bypass properties.

In Experiment 3 (Paper I), supplementation of fresh Tithonia foliage with leaves of Erythrina variegate doubled the N retention of goats compared with Tithonia supplemented with banana leaves and there were similar improvements in N retention when jackfruit leaves were given as a supplement to Tithonia foliage. These findings indicate that the protein in the banana leaves may have been over-protected as the leaves are known to have high levels of tannins (AGRIS, No date) as well as being high in NDF (Table 1).

 

4. Conclusions and recommendations

• The higher N retention and live weight gain in goats when Tithonia foliage was supplemented with cassava root chips and/or mulberry leaves confirms the original hypothesis that "the nutritive value of Tithonia foliage for goats would be improved by supplementing it with: a source of carbohydrate readily fermentable in the rumen and with tree foliages that would supply bypass protein.

• The situation presented by fresh Tithonia foliage is similar to what happens when a low digestibility crop residue (wheat straw) is treated with urea (Weixian et al 1994), or a high digestibility feed (molasses) is supplemented with urea and minerals (Preston and Willis, 1974). In each case the potential nutritive value of the basal diet was increased, but the expression of this improvement in the form of faster growth rates required supplementation with bypass protein to increase protein flow to the lower gut.

• Tithonia foliage has similar characteristics to these types of diet. It has a high potential nutritive value as the DM is highly digestible and rich in crude protein. However, the expression of this potential requires a strategy which will increase the supply of "metabolic" protein to the animal, which in the present study was achieved either by supplementation with cassava root chips (to increase rumen microbial production) and/or mulberry leaves (a source of bypass protein).
   

5. Acknowledgements

I would like to express my sincere thanks to Dr. Thomas Reg Preston, my supervisor who had given me many useful recommendations, criticism and correction on my thesis writing carefully.

I also would like to express my deep gratitude to all professors, lecturers and their assistants for their transference of useful knowledge to all students in this course. And sincere thanks to Professor Dr. Brian Ogle and Professor Dr. Inger Ledin, the ….. of MEKARN project, which was supported by SIDA SARREC, Swedish fund.

My special thanks to all staff in The Faculty of Agriculture, National University of Laos especially Mr. Thonly Xayachack, Mr. Fongsamuth Suthammavong, the dean and vice dean of the faculty and Mr. Kham Phommachan, the chief of Livestock and fisheries department, who had given me the agreement and allowance to participate this course. Furthermore, they facilitated the essential materials, laboratory and provided assistants to me during my experimental work time.

Grateful thanks to Dr. Bounthong Bouahom, Director of National Agriculture and Forestry Institute for supporting, consultant and commends.

I thank my classmates from Laos, Cambodia, Vietnam and Thailand for their good relationship.

Finally, I would like to say many thanks to my parents, brothers and sisters for their giving moral support, love and anxiety.
 

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