Tree legume supplementation improves mineral status of grazing does and growth performance of their kids

E Uemura, M Hayashida, E A Orden and T Fujihara

Faculty of Life and Environmental Science, S himane U niversity, Matsue City, Japan
tfuji1943@yahoo.co.jp
* Department of Bioproduction Technology, J unior College of Tokyo University of Agriculture, Setagaya-ku, Tokyo, Japan
Small Ruminant Center, Central Luzon State University, Science City of Munoz, Nueva Ecija, the Philippines
* Philippine Carabao Center, Science City of Munoz, Nueva Ecija, the Philippines

Abstract

A total of 35 crossbred does (50% Native x 50% Anglo Nubian) were used in an on-farm trial to develop use of inexpensive mineral sources using locally available foliages (Leucaena leucocephala and Gliricidium sepium) in a typical lowland-rain-fed area in villages in the Province of Pangasinan, Philippines. The animals were raised by small-holder farmers by either free-grazing or tethering without any concentrate supplementation. Leucaena leucocephala and Gliricidia sepium leaves were fed to 17 does and their blood and plasma mineral levels monitored and compared to the unsupplemented group (Control) with 18 animals. Bi-monthly blood samples of the grazing does were collected through the jugular vein and forage samples from the pasture areas were taken for macro and micro mineral assay.

The beneficial effect of tree-legume supplementation was manifested by higher blood Se level of does fed with Leucaena and Gliricidia than those in the Control during the rainy season but not during the dry season. Some of the animals that were lactating in the dry season had blood Se below the critical level (20 ng/ml) despite the feeding of tree-legumes. Although tree-legumes were effective in improving the Se status of the animals during the rainy season, the serious problem of feed scarcity during dry lean months resulted in subclinical symptoms of Se deficiency despite the feeding intervention. On the other hand, other plasma mineral levels were not affected by tree-legume supplementation, indicating that sulfur (S), calcium (Ca), magnesium (Mg), copper (Cu), iron (Fe) and zinc (Zn) contents of feed resources under this agro-climatic condition are sufficient to meet daily needs. Aside from improving the Se status, does fed with tree-legumes produced bigger kids at birth. Moreover, growth performance of their kids was better than for those kids born from does in the Control group.

Key words: Gliricidia, leucaena, Philippines, selenium

Introduction

Goats are important in most tropical and sub-tropical countries due to their wide adaptability to various environments and inherent ability to thrive under low plane of nutrition. They are usually raised by small-holder farmers by free-grazing or tethering in native vegetation and feeding of available crop residues. The feeding value of these feed resources is generally poor with very limited energy, protein and mineral contents. As a consequence, goats often suffer from various levels of nutritional deficiencies and imbalances that adversely affect their productivity (McDowell 1985).

In the Philippines, it has been previously reported that about 55% of grazing goats in Luzon Island suffered from sub-clinical signs of Se deficiency (Fujihara et al 1992). Furthermore, Orden et al (1999) and Serra et al (1996, 1997) reported that mineral elements in most locally available forage materials in these areas were relatively low and affected the mineral status of grazing goats, especially micro elements Zn and Se. Realizing the possible adverse effect of prolonged exposure of animals to mineral deficiency, Hayashida et al (2003a, b; 2004a, b) conducted studies that focused on the development of low-cost feeding interventions to provide supplemental minerals to physiologically active female goats and stall-fed growing kids. This research undertaking was dubbed as “improving the mineral status of goats in chevon-producing areas of Central and Northern Luzon” that involved concentrate or tree legume supplementation and administration of mineral glass-bolus in improving the mineral status of pregnant and lactating does.

The objective of the present study was to determine the effect of ad libitum feeding of Leucaena leucocephala and/or Gliricidia sepium (Photo 1) on the mineral status of F₁ does (50% Native x 50% Anglo Nubian) grazing in lowland rainfed areas in Northern Luzon. The birth weight and growth performance of the kids produced by does that were fed with tree legume supplements were also evaluated.


Photo 1. Goats browsing Leucaena and Gliricidia

Materials and Methods

Experimental Site

The trial was conducted in the farms of seven selected goat-farmers in the Province of Pangasinan, Philippines. The site is located at 15.4º North Latitude and 120.5ºEast Longtitude with two distinct seasonal patterns; rainy (June–November) and dry (December-May). Average annual precipitation is from 1,800 to 2,500mm; about 20mm/month during dry season and 200-500mm/month in rainy season. Average annual temperature ranges from 26 to 33ºC.

Experimental animals, diet and treatment

Prior to the start of the trial, blood samples were collected from 10 randomly selected does to check and establish bench mark data on the Se status of the animals. The Se assay showed that average blood Se level was close to the critically low level that warrants feeding interventions.

A total of 35 crossbred does (F₁ Anglo Nubian crosses) were selected and randomly distributed into 2 treatment groups:

CTL: 17 does, freely grazing without tree legume supplementation

LL-GS: 18 does, freely grazing supplemented with Leaucaena (Leaucaena leucocephala) or Gliricidia (Gliricidia sepium).

The animals were provided with housing where they were herded during the night. Fresh drinking water was available at all times.

The macro and micro-mineral content of dominant forage species in the grazing and tethering area of the experimental animals is presented in Tables 1 and 2 (Hayshida et al., 2004). Leaucaena and Gliricidia were better sources of mineral elements than grasses. Calcium, Mg, Fe and Cu contents of both grasses and tree legumes were adequate. Sulfur content of P. purpurem and P in Leucaena were below the critical level during dry and wet season. Except for C. plectostachyus and Leaucaena, Cu and Zn concentrations of most species during wet and dry season were sufficient to meet the daily requirement of grazing does. Although Se content of Leucaena, P. purpurem and B. mutica is above the critical level of 50ηg/gDM (McDowell, 1984), majority of forage species that served as the primary feed for the grazing does had low Se level.

Sample Collection and Mineral Analysis

About 10 ml blood sample were bi-monthly through the jugular vein of the animals using vacuous tube that contained heparin as anti-coagulant. Immediately after collection, 1 ml whole blood was taken from the 10 ml blood sample for Se analysis, while the remainder was centrifuged at 3,000 rpm for 20 min to separate plasma from courp cells. Thereafter, 1 ml plasma was taken and transferred into 10ml acid-washed test tubes for mineral analysis. All whole blood and plasma samples were stored at -80 ^oC until mineral analysis. Likewise, bi-monthly forage samples were collected in the grazing area using pluck sampling technique. Fresh samples were dried and ground to pass through a 1mm mesh sieve using Willey Mill. Ground samples were placed in plastic container and kept under room temperature.

Forage samples were digested with nitric acid while the whole blood and plasma samples with nitric and perchloric acid (3:1 v/v) using microwave-oven (MDS-2000, CEM Co., NC, USA. After cooling, samples were diluted with deionized distilled water to a final volume of 50 ml. Thereafter, Se was analyzed through the fluorometric detection of 2, 3-diaminonaphthalene (DAN) following the procedure of Watkinson (1966). The spectrofluoro photometer used was RF-1500 (Shimadzu Co., Japan).

On the other hand, sulfur (S), calcium (Ca), phosphorus (P) , magnesium (Mg), copper (Cu), zinc (Zn) and iron (Fe) were determined using Inductively Coupled Plasma Emission Spectroscopy (ICPU-2000, Shimadzu Co., Kyoto, Japan). All glass wares used during the mineral analysis were acid washed with nitric acid to prevent possible contamination.

Table 1. Macro-mineral contents of forage species consumed by goats in low-land rain-fed areas of the Pangasinan (% in DM)^*
	Sulfur (0.16-0.35)^#		Calcium (0.21-0.52)#		Phosphorus (0.16-0.37)#		Magnesium (0.16-0.34)#
	Dry	Wet	Dry	Wet	Dry	Wet	Dry	Wet
Graminasea*
Penisetum purpureum	0.13	0.15	0.44	0.49	0.28	0.28	0.22	0.20
Braciaria Mutica	0.45	0.42	0.49	0.42	0.23	0.28	0.33	0.37
Paspalumum conjugatum	0.49	-	1.11	-	0.22	-	0.27	-
Cynodon plectostachyus	-	0.28	-	0.52	-	0.23	-	0.22
Leguminosae
Leucaena leucocephala	0.49	0.48	2.65	2.48	0.25	0.25	0.42	0.43
Gliricidia sepium	0.33	0.32	2.33	2.36	0.30	0.29	0.46	0.60
^* Hayashida et al (2004a). ^# Critical level (McDowell 1985)

Table 2. Micromineral contents of forage species consumed by goats in low-land rainfed areas of the Pangasinan*
	Copper (4.0-10.0)^# mg/kg DM		Zinc (30-50)# mg/kg DM		Iron (>30) mg/kg DM		Selenium (50-300)# ng/kg DM
	Dry	Wet	Dry	Wet	Dry	Wet	Dry	Wet
Graminasea*
Penisetum purpureum	24.1	23.4	30.8	31.6	385	163	67.6	65.2
Braciaria Mutica	14.7	20.1	76.8	57.0	-	222	106	116
Paspalumum conjugatum	8.9	-	53.0	-	-	-	35.8	-
Cynodon plectostachyus	-	1.6	-	50.6	440	368	-	58.9
Leguminosae
Leucaena leucocephala	9.4	8.9	30.4	28.0	365	339	43.1	47.7
Gliricidia sepium	6.4	6.3	31.7	27.0	192	192	38.4	45.3
^* Hayashida et al (2004a) # Critical level (McDowell 1985)

Birth Weight and Live Weight of Kids

A total of 81 kids (43 in Control and 38 in legume supplemented group) were produced during the course of the on-farm trial. Birth weight and live weight of kids at 1-month and 3-month old were recorded to determine the effect of tree legume supplementation on the growth rate (average daily gain) of the does’ offspring.

Plasma and whole blood mineral concentrations, birth weight, and live weight were subjected to statistical analysis using t-test (Yoshida 1975)

Results

The plasma concentration of macro-minerals (S, Ca, P and Mg)

Plasma S, Ca, P and Mg content of the does are shown in Table 3. In the month of June (wet season), plasma S level of does fed with tree-legume leaves was higher (P<0.05) than the control. Although plasma S level tended to be higher in the legume-supplemented group, it was found to be similar with the control during the succeeding months within the 1-year period of the trial. Likewise, no significant variation was observed in the other months. Interestingly, however, mean plasma S level was higher than the critical level of 500μg/ml for does (McDowell 1985) with very minimal seasonal variation.

Table 3. Plasma S, P, Ca and Mg level of grazing does as influenced by legume tree supplementation
	June	August	October	December	February	April
S (µg/ml)
Control	982±16.5^b	928±26.3	1029±18.0	1013±23.1	988±20.4	1042±24.1
Supplemented	1088±29.3^a	975±21.0	1046±27.4	1041±27.9	994±23.3	1082±25.2
P (µg/ml)
Control	95.1±3.2	77.2±2.4^b	87.2±5.31	104±4.1	93.0±5.1	84.9.1±3.2
Supplemented	97.4±3.6	93.4±3.7^a	88.9±3.9	104±9.7	89.6±3.1	85.3±3.3
Ca (µg/ml)
Control	98.6±2.0	95.0±3.2	101±2.8	100±2.6	108±1.8	106±1.4
Supplemented	101±2.1	98.7±1.1	100±2.1	99.6±3.4	104±1.5	100±8.4
Mg (µg/ml)
Control	24.6±0.4	28.3±0.6	30.2±1.2	25.6±0.7	28.2±0.9	27.8±1.0
Supplemented	25.3±0.7	27.4±0.7	28.3±1.5	26.2±0.7	29.4±1.5	27.7±0.9
^ab Mean values in columns within mineral elements with different superscripts differ at P<0.05)

The feeding of tree legumes did not result in significant variations in plasma Ca and Mg levels among the grazing does and bi-monthly averages were way above the critical limit of 70μg Ca/ml and 18μg Mg/ml (McDowell 1985) during the period. Likewise, there was no clear seasonal change in plasma Ca and Mg.

Conversely, a positive effect of tree-legume supplementation was observed during the wet season where significantly higher plasma P (P<0.05) level was recorded among supplemented does than those in the control during the months of August and September. Similar with the other macro minerals, mean plasma P levels were above the critical level of 40μg/ml without clear seasonal variation throughout the year.

The plasma concentration of micro-minerals (Cu, Fe and Zn)

As shown in Table 4, the plasma Cu and Fe levels of the does were almost similar in both groups throughout the year without any distinct variation as influenced by the feeding intervention. Mean plasma Cu and Fe values were way above the critical level 0.6μg/ml (McDowell 1985) with no clear seasonal variation. However, Fe level in plasma of does was found to be exceedingly high at start of the experiment, 6.32 μg/ml for the supplemented group and 4.89 μg/ml for the control, but mean values gradually decreased as the trial progressed.

Although plasma Zn concentration was similar for the tree-legume supplemented and control groups, some of the does had plasma Zn content below the critical level of 1.0 μg/ml (McDowell 1985). During the rainy season, five (5) does in the control exhibited way below the critical limit of 1.0μg Zn/ml in the month of June, August and October. Likewise, five (5) does in the control had plasma Zn levels below the critical value in the dry season months of December, February and April. It should be pointed out that although no clear clinical symptoms of Zn deficiency was exhibited by these animals, two does were possibly suffering from sub-clinical Zn deficiency since they have consistently showed way below the critical limit of 1.0 μg Zn/ml of plasma during the rainy and season.

Table 4. Plasma Cu, Fe, Zn, and whole blood Se level of grazing does as influenced by legume tree supplementation
	June	August	October	December	February	April
Cu (µg/ml)
Control	1.04±0.04	1.04±0.04	1.21±0.08	1.06± 0.04	1.04±0.04	1.30±0.09
Suplemented	1.01±0.05	0.98±0.05	1.17±0.07	1.06±.0.02	1.19±0.20	1.27±0.09
Fe (µg/ml)
Control	4.98±0.55	3.12±0.23	3.66±0.55	4.06±0.28	3.66±0.34	2.91±0.11
Suplemented	6.32±1.13	3.44±0.20	3.27±0.75	4.69±0.94	3.54±0.25	3.51±0.39
Zn (µg/ml)
Control	1.05±0.08	0.99±0.06	1.06±0.05	1.06±0.11	1.00±0.06	0.85±0.06
Suplemented	1.16±0.08	0.90±0.05	0.98±0.08	1.36±0.20	1.01±0.06	1.13±0.26
Se (ng /ml)
Control	56.7±6.54^b	55.7±6.75	25.2±2.94^b	20.2±1.74	39.5±4.28	41.6±6.30
Suplemented	88.7±11.6^a	75.8±7.68	47.9±4.98^a	20.1±1.64	32.9±3.56	32.0±3.11
^{a, b}Values in the same column within mineral elements with different superscripts differ at P<0.05.

Se concentration in whole blood

There was a clear seasonal variation in the blood Se level of does as influenced by the feeding intervention (Table 4). The supplementation of tree legumes resulted in significantly higher (P<0.05) blood Se level of grazing does than those in the control during rainy season (June, August and October). Except for 2 animals that had blood Se lower than the recommended 20ng/ml (McDowell 1985) in the Control group during the month of August and October, mean values were above the critical level. This would indicate that Se status of the animals is generally within the normal level.

In contrast, blood Se level during the dry season months of December, February and April did not differ significantly (P>0.05) and there were more animals that exhibited sub-clinical signs of Se deficiency as 6 does in the Control group had blood Se below critical level. Results tend to suggests that tree legume supplementation is effective in improving Se status of grazing does under farm level during rainy season when forage supply is abundant but not during dry season when there is a serious problem of feed scarcity. With more animals having blood Se below the critical level of 20ng/ml in the Control group would indicate that a more pronounced effect of tree legume supplementation is expected during lean months than when there is surfeit of feed. Availability of feed resources in the grazing areas of a typical rice-farming village of the Province of Pangasinan is greatly dependent on rainfall pattern.

Birth weight and growth performance of kids

Bigger and heavier (P<0.05) kids at birth were produced by does receiving tree-legume supplementation than those in the Control group (Table 5). Moreover, the positive effect of legume supplementation was observed in the live weight of pre-weaning kids as they matured from 1-month to 3-month. Kids from dams that were fed with tree legume had higher growth rate that resulted in higher live weight at 3 months of age.

Table 5. Live weights of kids born from does fed with (LL-GS) and without (CTL) tree legume supplementation
	CTL*	LL-GS#	SEM	p
Live weight, kg
Birth	2.53	3.17	0.06	<0.001
30 days	3.27	4.36	0.12	<0.001
90 days	6.38	9.42	0.25	<0.001
Weight gain, g/day
0-30 days	24.8	39.9	3.12	0.015
0-60 days	51.7	84.2	3.37	<0.001
0-90 days	42.8	69.4	2.37	<0.001
^ Mean of 38 kids. ^#Mean of 43 kids.*

Discussion

Tree legumes provide higher amounts of essential trace elements than most grass species grazed by does in goat producing regions of Luzon Island (Fujihara et al 1992; Serra et al 1996; Orden et al 2000). These findings showed that Se is below the critical level in most forage species that necessitates feeding intervention. Moreover, Hayashida et al (2004) pointed out the Se content of Leucaena leucocephala and Gliricidia sepium increased during the on-set of the rainy season. Mineral analysis of available feed resources in this on-farm trial showed similar trend as far as Se is concerned (Tables 1 and 2). With relatively higher amount of Se during rainy season, blood Se concentration was significantly increased from July to September among grazing does that were provided with either Leucaena or Gliricidia leaves than those animals that were purely grazing (Table 4). These findings clearly showed the positive effects of tree legume supplementation in improving Se status of pregnant and lactating does that are grazing in marginally utilized areas in the farming villages of the province of Pangasinan.

Despite tree legume supplementation during dry summer months, some does in the treated group had relatively low Se level indicating that the amount of available Se in the grazing area is not enough to meet Se requirement of physiologically active female goats. Plausibly, the observation of Orden et al (2005) that the proportion of leguminous browse species to the total available feed resources in these areas decreased by more than 18% as the season shifted from rainy to dry season might have contributed to the below normal blood Se in some of the animals. Legumes are known to accumulate greater amount of Se than other forage species (McDowell 1985; Minson 1990). Hayashida et al (2004) pointed out that although Se concentration of leaucaena leaves varied greatly according to season, its Se content was higher (P<0.05) than grasses (Pennisetum purpurem, Brachiaria mutica, Paspalum conjugatum and Cynodon plectostachyus) commonly fed to mature goats under total confinement. Therefore, with lesser leguminous species during the months of March to May, the amount of forage-Se decreased in the grazing area.

Tree legume supplementation did not affect the macro mineral status of the does. The plasma S, Ca, P and Mg did not vary significantly during the course of the on-farm trial and no manifestation of sub-clinical sign of deficiency was observed in both dry and wet season. Apparently, the forage species along roads, paddy dikes, vacant lots and communal pasture areas provided wide variety of macro-mineral sources where goats can freely browse.

Likewise, plasma Cu level was relatively steady without any indication of significant variability and no animal manifesting below critical level. The findings tend to suggest that the farmer’s practice of free grazing or tethering of physiologically active goats under this farming condition in low-land rainfed areas in Pangasinan is unlikely to result in Cu deficiency symptoms such as ataxia, achromatrexia, lameness and anemia (Zervas 1988) even without any form of supplementation.

The low plasma Zn concentration observed in some animals in both the Control and supplemented groups confirmed our previous observation (Fujihara et al 1992) that grazing goats in most areas in Central and Northern Luzon had poor Zn status. As shown in Table 2, plasma Zn level of does below the critical level of 1μg/ml were recorded during the months of August and April (Control), and August and October (Supplemented group). These are clear indications that pregnant and lactating does are exposed to Zn deficiency regardless of season. Not even the provision of tree legume supplement was effective in improving the Zn status of the animals. Physiologically, Zn is a component of alkali-phosphatase whose role in the animal body is associated to normal growth and development, and reproductive functions. Given this condition, there is really a need to provide feeding interventions that will improve Zn status of physiologically active female goats to minimize the adverse affect of long-term exposure to Zn deficit forage diets. Therefore, any form of Zn supplementation has to be employed for sustainable goat production in most areas of the Luzon Island to prevent the debilitating effect of Zn deficiency.

Aside from the positive effect of tree legume supplementation in improving the Se status of grazing mature female goats in the low-land rain-fed areas of Umingan, Pangasinan, another benefit derived is the production of bigger offspring. Apparently, kids born from dams that received tree-legume supplements had more milk to suckle that resulted in a growth rate of 84.2g compared to only 51.7g in the Control. Under backyard management system, weaning period could last for 3-4 months and kids depend on the dam’s milk for their nourishment. Therefore, growth performance of kids during pre-weaning is an indication of the dam’s mothering ability and the amount of milk available for suckling. Results support the findings of Dahlanuddin (2004) and Ondiek et al (1999) that the feeding of Sesbania grandiflora, Leaucaena leucocephala and Gliricidia sepium in equal proportion to pregnant and lactating does increased milk production and dramatically reduced kid mortality and significantly improved growth performance of suckling kids. When forage legumes were processed into pellets, Orden et al (2013) observed that lactating Anglo-Nubian crosses fed with Leucaena-based pellets had average milk production of 587 ml/day for 105 days lactation period. Likewise, Abdullah et al (2012) demonstrated the positive effects of pelleted legumes (Indigofera leaves) in increasing milk yield of dairy goats from 121 to 383 mL/day. And more importantly, it lowered feed cost and feed conversion values in comparison with commercial dairy concentrates.

Macro and micro mineral concentration in plasma indicated that grazing does had more or less stable source of S, Ca, P, Mg, Cu and Fe. Only Se appeared to be highly variable and tend to deficits in some periods. The sudden drop of blood Se level in the supplemented group during the dry season that started in December could be due to the following reasons; 1) feed scarcity during dry lean months, 2) decrease of Se content in the tree-legume supplements, 3) lesser proportion of leguminous browse species in the grazing area, and 4) most of the does were lactating during this period where there is increased Se flow from the blood stream into the mammary system.

Conclusions and Implications

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