Mineral content in range forages from north Mexico

Abstract

Native forages such as trees Quercus eduardii and Quercus grisea; shrubs such as Atriplex canescens, Acacia constricta, Acacia shaffneri, Cassia wislizeni, Celtis pallida, Condalia lycioides, Cordia parvifolia, Flourencia cernua, Larrea tridentata, Mimosa biuncifera and Prosopis leavigata; forbs such as Coldenia greggii, Dalea bicolor, Jatropha dioica and Parthenium incanum; cacti such as Opuntia imbricata, Opuntia leptocaulis and Opuntia leucotricha; red and white fruits from O. leucotricha; fruits from O. leptocaulis, O. imbricata and A. canescens; pods from P. leavigata; pods from A. shaffneri and flowers from Yucca spp. were collected to estimate and compare the mineral content. Plant samples were collected during the dry and wet seasons of two consecutive years (2006–2007) at seven locations situated in four counties of the state of Durango, Mexico. All macrominerals and trace elements were significantly different among plants within each group of plants. The Ca, Mg, K, Fe and Mn content of most plants were in sufficient amounts to satisfy adult range requirements; however, P, Na, Cu and Zn resulted with marginal deficiencies.

Keywords:

• native forages
• digestibility
• mineral content
• north Mexico

Introduction

Native range plants are indispensable sources of animal feed, particularly in areas with dry to semi-dry climates (Juarez-Reyes et al. 2004). Such species can alleviate feed shortages, or even fill feed gaps in the winter and especially in the summer, when grassland growth is limited or dormant due to unfavourable weather conditions. These include several shrubs, small trees, spontaneous forbs, fruits, flowers, pods and cacti which are essential components of natural communities such as shrublands and woodlands (Juarez-Reyes et al. 2008). They cover large areas and constitute grazing lands for all domestic and wildlife small ruminants (Ramírez-Orduña et al. 2003). However, forage production and nutritive value vary widely among species, varieties, plant parts, phenological state and seasons of the year. In general, they have a good content of crude protein (CP; Moya-Rodriguez et al. 2003), minerals and vitamins; whereas are high in fiber, ash and lignin (Ramírez-Orduña et al. 2008).

Pawelek et al. (2008) argued that essential minerals are important in preventing diseases and inhibiting or stimulating ruminal microbial activity. However, in some situations such as high fiber content that inhibit mineral release (Čerešňáková et al. 2007), they are deficient in one or more minerals and supplementation is required for optimal animal performance and health (McDowell 2003). Thus, the aim of this study was to determine the mineral content of 28 native forages and compare among each life form of plants.

Materials and methods

Plant species were collected from seven locations situated in four counties (Durango, Guadalupe Victoria, Peñon Blanco and Cuencame) of the state of Durango, Mexico. Durango county is located at 23° 29′ and 24° 26′ N and 104°06′ and 105° 34′ W. The altitude varies between 1860 and 2400 mosl. The climate is dry and semiarid and annual mean temperature varies from 13° C to 19° C, annual precipitation varies from 722 mm to 1604 mm. The main soil types are regosol and litosol. Guadalupe Victoria county is located at 24° 07′ and 24° 41′ N and 103° 54′ and 104° 16′ W. It has an altitude that ranks from 1970 to 2100 mosl. The climate is dry semiarid with an annual mean temperate that varies from 5 to 18° C and annual precipitation from 215 to 811 mm. Mainly soil types are feozem, cambisol and litosol. Peñon Blanco county is located at 24° 28′ and 25° 04′ N and 103° 47′ and 104° 19′ W, with an altitude that varies from 1580 to 1910 mosl. The region is considered dry and semiarid. The annual mean temperature ranks between 15 and 20°C and the annual mean precipitation varies from 260 to 300 mm. The main soil types are rendzina and litosol. Cuencame county is located at 24° 01′ and 25° 16′ NL, and 103° 22′ and 104° 01′ WL, altitude varies from 1300 to 2170 m. The climate is dry and semiarid. Mean temperature varies from 14 to 21°C and the annual precipitation ranks from 95 to 710 mm. The main soil types are xerosol and litosol (INEGI 2004).

Foliage from trees such as Quercus eduardii and Quercus grisea; shrubs such as Atriplex canescens, Acacia constricta, Acacia shaffneri, Cassia wislizeni, Celtis pallida, Condalia lycioides, Cordia parvifolia, Flourencia cernua, Larrea tridentata, Mimosa biuncifera and Prosopis leavigata; forbs such as Coldenia greggii, Dalea bicolor, Jatropha dioica and Parthenium incanum; cacti such as Opuntia imbricata, Opuntia leptocaulis and Opuntia leucotricha; red and white fruits from O. leucotricha, fruits from O. leptocaulis, O. imbricata and A. canescens; pods from P. leavigata; pods from A. shaffneri and flowers from Yucca spp. were collected for mineral analyses. Plants chosen for each species were selected at random, taking at least 10 plants of each species, considered as dominant in the range (Pawelek et al. 2008). Tree, shrub and forb samples were air dried until constant weight. Cacti samples were burned and air dried. Flowers, fruits and pods were dried in an air forced oven at 55°C until constant weight.

Quadruplicate samples of each plant species were used for mineral analyses. Partial dry matter (DM) was determined subjecting samples to oven at 55°C during 72 h, then were ground in a Wiley mill (1 mm) and stored in plastic containers until further analyses. Mineral content was estimated by incinerating samples in a muffle oven at 550°C, during 5 h. Ashes were digested in a solution containing HCl and HNO₃, using the wet digestion technique (Cherney 2000). Concentrations of Ca and Mg (oxide nitrous/acetylene flame), K, Na, Cu, Fe, Mn and Zn (air/acetylene flame) were determined by atomic absorption spectrophotometry using a Varian spectrophotometer (model SpectrAA-200; Varian Australia Pty Ltd., Mulgrave, Victoria, Australia); whereas, P was quantified spectrophotometrically using a Perkin-Elmer spectrophotometer (model Lamda 1A; Perkin-Elmer Corp., Analytical Instruments, Norwalk, CT, USA) (AOAC 1997). Data were analysed among species within each group of plants by one way analysis of variance using the general linear model procedure of SAS (1997). Mean differences were tested using the Tukey's test (Steel and Torrie 1980).

Results and discussion

The macrominerals Ca, P, K, Mg and Na concentrations significantly varied among plants within each group of plants (Table 1). The Ca content was higher in cacti species (ranged from 68 to 118 g kg⁻¹ DM) followed by flowers, fruits and pods (4–79), shrubs (9–68), forbs (15–29) and trees (8–11). It appears that all plants had substantial amounts of Ca to meet requirements of adult range ruminants (4.6, 5.1, 3.0 and 5.3 g of Ca kg⁻¹ of diet DM for beef cattle, sheep, goats and white tailed deer, respectively; NRC 2000, 2007). In addition, Cerrillo-Soto et al. (2004) in north Mexico, Ramírez-Orduña et al. (2005) in northwest Mexico and Ramírez-Lozano et al. (2010) in northeastern Mexico reported that native plants growing in semiarid regions had enough Ca for optimal range goats, sheep and white tailed deer performance, respectively. Except for the pods of P. leavigata, all plants in this study had Ca content above 8.0 g kg⁻¹.

Table 1. Macromineral content (g kg⁻¹ DM) in range plants growing in North Mexico.

Plants	Ca	P	Mg	Na	K
Trees
Quercus eduardii	11^a	1.6^a	2^a	0.6^a	4^a
Quercus grisea	8^b	1.4^b	1^b	0.8^a	3^b
Mean	9	1.5	2	0.7	3
EEM	0.4	0.1	0.1	0.1	0.5
Significant level	***	*	**	Ns	**
Shrubs
Atriplex canescens	22^e	3.1^bcd	10^a	1.8^a	56^a
Flourencia cernua	68^a	1.5^g	6^c	0.5^def	7^efg
Caliandra eriophylla	26^d	0.9^h	2^gh	0.3^f	6^fgh
Celtis pallida	18^fg	3.2^abc	2^fg	1.6^b	27^b
Condalia lyciodes	41^c	3.8^a	4^d	0.4^ef	4^fgh
Acacia constricta	21^ef	1.9^fg	1^h	1.0^cde	9^defg
Larrea tridentata	21^ef	2.2^ef	4^de	1.0^cde	14^cd
Cordia parvifolia	18^fg	2.7^de	3^ef	1.0^bcd	5^fgh
Mimosa biuncifera	15^g	1.6^g	2^gh	1.0^bcd	4^gh
Cassia wislizeni	11^h	3.2^bc	3^fg	0.6^def	11^de
Acacia shaffneri	9^h	3.0^cd	2^fgh	1.0^bcd	10^def
Prosopis leavigata	53^b	3.6^ab	7^b	1.5^bc	17^c
Mean	27	2.5	4	1.3	14
EEM	1	0.2	0.4	0.1	0.5
Significant level	***	***	***	***	***
Forbs
Jatropha dioica	23^ab	2.2^b	6^a	1.1^a	22^a
Dalea bicolor	29^a	2.1^b	2^b	0.9^ab	23^a
Panthenium incanum	15^c	2.1^b	2^b	0.9^ab	9^b
Cassia greggii	18^bc	3.7^a	3^b	0.5^b	8^b
Mean	21	2.5	3	0.8	16
EEM	1	0.2	1	0.2	1
Significant level	***	***	***	**	***
Cacti
Opuntia leucotricha	68^c	0.7^a	10^a	0.6^a	23^a
Opuntia leptocaulis	103^b	0.6^a	7^b	0.5^a	8^b
Opuntia imbricata	118^a	0.5^a	5^c	0.6^a	10^b
Mean	97	0.6	7	0.6	14
EEM	1	0.1	0.5	0.1	1
Significant level	***	***	***	*	***
Flowers, fruits and pods
Yucca spp. FL	9^f	5.2^a	2^e	0.5^b	18^c
Opuntia leucotricha W	37^c	3.1^c	6^b	0.8^ab	20^bc
Opuntia leucotricha R	34^d	3.2^c	4^d	1.1^a	26^b
Opuntia leptocaulis F	79^a	3.3^c	5^c	0.5^b	9^de
Opuntia imbricata F	44^b	3.8^b	4^d	0.6^b	16^cd
Atriplex canescens F	15^e	3.3^c	7^a	0.9^ab	50^a
Prosopis leavigata P	4^g	2.7^d	1^f	0.5^b	16^cd
Acacia shaffneri P	8^f	1.7^e	1^f	0.5^b	7^e
Mean	29	3.3	4	0.6	20
SEM	1	0.1	0.2	0.2	1
Significant level	***	***	***	**	***
Grand mean	33	2.5	4	0.8	15
^a, ^b, ^c, ^d, ^e, ^f, ^g, ^hMeans in a row with different letter superscripts, in each group of plants, are different (P<0.05).
***(P<0.001); **(P<0.01); *P(<0.05).
SEM, standard error of the mean; FL, flower; F, fruit; W, white prickly pear; R, red prickly pear; P, pod; ns, not significant.

The P content was higher in the plant group of flowers, fruits and pods (ranged from 1.7 to 5.2 g kg⁻¹ DM) followed by forbs (2.1–3.7), shrubs (0.9–3.8), trees (1.4–1.6) and cacti species (0.5–0.7). All species had P content (Table 1) that varied from 0.7 to 2.8 g kg⁻¹. Similar ranges were reported by Khanal and Subba (2001) in cultivated trees from Nepal. However, Dynesi and Schlink (2000) found lower ranges (0.5–1.1) in 10 acacia trees from Australia. In this study, with exception of trees and cacti, all plants had P contents that were sufficient to meet adult range ruminant requirements (2.3, 2.7, 2.8 and 2.6 g of P kg⁻¹ of diet DM for beef cattle, sheep, goats and white tailed deer, respectively; NRC 2000, 2007). In this study, low P and high Ca concentrations resulted in an unusually wide Ca:P ratios (Table 2). Similar wide Ca:P ratios had been reported by Kallaha et al. (2000). They also argued that although the levels of P in forages had been found to fall within the required range, the gross excess of Ca is likely to aggravate aphosphorosis in unsupplemented animals.

Table 2. Trace elements (mg kg⁻¹ DM) in range plants from North Mexico.

Plants	Cu	Fe	Mn	Zn
Trees
Quercus eduardii	4^a	154^b	63^a	16^a
Quercus grisea	2^b	208^a	48^b	16^a
Mean	3	131	56	16
SEM	0.2	3	1	1
Significant level	***	***	***	***
Shrubs
Atriplex canescens	12^bc	112^i	66^b	71^a
Flourencia cernua	4^de	167^fg	58^cd	17^ef
Caliandra eriophylla	3^e	162^g	24^g	14^f
Celtis pallida	15^b	312^b	52^de	67^a
Condalia lyciodes	7^de	193^ef	45^ef	17^ef
Acacia constricta	9^cd	129^hi	60^bc	18^ef
Larrea tridentata	22^a	374^a	84^a	62^ab
Cordia parvifolia	4^de	285^c	47^ef	32^d
Mimosa biuncifera	3^e	218^de	44^ef	33^cd
Cassia wislizeni	9^cd	239^d	43^f	26^de
Acacia shaffneri	4^de	153^gh	47^ef	54^b
Prosopis leavigata	12^bc	155^gh	43^f	43^c
Mean	9	208	51	38
SEM	1	4	2	4
Significant level	***	***	***	***
Forbs
Jatropha dioica	12^a	293^ab	53^b	24^b
Dalea bicolor	6^a	356^a	47^b	64^a
Panthenium incanum	5^a	121^c	82^a	31^b
Cassia greggii	12^a	257^b	57^b	60
Mean	8	257	62	45
SEM	1	2	2	3
Significant level	***	***	***	***
Cacti
Opuntia leucotricha	4^a	145^a	171^a	16^b
Opuntia leptocaulis	7^a	59^b	149^b	89^a
Opuntia imbricata	14^a	41^c	141^b	16^b
Mean	8	82	154	40
SEM	1	2	2	2
Significant level	***	***	***	***
Flowers, fruits and pods
Yucca spp. FL	14^a	58^d	8^f	70^b
Opuntia leucotricha W	5^bc	47^d	888^a	17^c
Opuntia leucotricha R	5^c	51^d	846^b	27^c
Opuntia leptocaulis F	6^bc	88^c	184^c	109^a
Opuntia imbricata F	7^b	131^b	129^d	23^c
Atriplex canescens F	7^b	308^a	79^e	18^c
Prosopis leavigata P	7^b	47^d	19^f	39^c
Acacia shaffneri P	6^bc	140^b	8^f	46^bc
Mean	7	109	270	44
SEM	1	3	7	3
Significant level	***	***	***	***
Grand mean	8	169	124	37
^a, ^b, ^c, ^d, ^e, ^f, ^g, ^h,iMeans in a row with different letter superscripts, in each group of plants, are different (P<0.05)***(P<0.001).
SEM, standard error of the mean; FL, flower; F, fruit; W, white prickly pear; R, red prickly pear; P, pod.

The Mg content (Table 2) was higher in cacti species (range from 5 to 10 g kg⁻¹ DM) followed by shrubs (1–10), flowers, fruits and pods (1–7), forbs (2–6) and trees (1–2). It seems that most tested plants had Mg concentrations to meet adult range ruminant requirements (1.0, 1.5, 1.6 and 1.6 g of Mg kg⁻¹ of diet DM for beef cattle, sheep, goats and white tailed deer, respectively; NRC 2000, 2007). Other studies have found that browse plants from northeastern (Ramírez-Lozano et al. 2010), northwestern Mexico (Ramírez-Orduña et al. 2005), southern Iran (Sameni and Solemani 2007) and Australia (Dynesi and Schlink 2000) had sufficient amounts of Mg to meet requirements of adult range ruminants.

Sodium content (Table 2) resulted with higher ranges in shrubs (from 0.3 to 1.8 g kg⁻¹ DM) followed by forbs (0.5–1.1), trees (0.6–0.8), flowers, fruits and pods (0.5–0.8) and cacti species (0.5–0.6). In this study, only a few plants had Na content to meet the needs (0.7, 1.0, 0.8, 1.1 and g of Na kg⁻¹ of diet DM for beef cattle, sheep, goats and white tailed deer, respectively; NRC 2000, 2007) of growing adult range ruminants. Sodium is considered the mineral most limiting to growth and reproduction of mammalian herbivores worldwide (Whitehead 2000). High K content (range = 3–56 g kg⁻¹ DM) in evaluated plants (Table 1) could reduce Na absorption of range ruminants feeding these plants (McDowell 2003).

Except for the trees Q. eduardii, Q. grisea and shrubs Condalia lyciodes, L. tridentate and C. parvifolia, all plants had substantial amounts of K to meet the requirements of range ruminants (6.0, 6.5, 4.6 and 4.6 g of K kg⁻¹ of diet DM for beef cattle, sheep, goats and white tailed deer, respectively; NRC 2000, 2007). Similar findings were reported by Dynesi and Schlink (2000), Cerrillo-Soto et al. (2004), Ramírez-Orduña et al. (2005), Sameni and Solemani (2007) and Ramírez-Lozano et al. (2010) who evaluated K content in native range forages growing in arid and semiarid regions of the world.

Contents of trace elements such as Cu, Fe, Mn and Zn were significantly different among plants within each group of plants (Table 2). Copper content was higher in shrubs (ranged from 3 to 22 mg kg⁻¹ DM) followed by forbs (5–12), cacti (4–14), flowers, fruits and pods (5–14) and trees (2–4). Apparently, only a few plants had Cu levels that could meet adult range ruminant requirements (11, 9, 9 and 9 mg of Cu kg⁻¹ of diet DM for beef cattle, sheep, goats and white tailed deer, respectively; NRC 2000, 2007). Low Cu concentrations are also reported in shrubs and trees from semiarid regions (Cerrillo-Soto et al. 2004; Ramírez-Orduña et al. 2005; Ramírez-Lozano et al. 2010). Low Cu levels in plants might be caused because of the high pH of the soils of these regions (Whitehead 2000), which are about from 7.5 to 8.5. High levels of Fe content in evaluated plants (51–374 mg kg⁻¹ of diet DM) may reduce the availability of Cu (NRC 2007).

Iron content was higher in forbs (range = 121–356 mg kg⁻¹) followed by shrubs (112–374), trees (154–208), flowers, fruits and pods (47–308) and cacti species (41–145). Except for the cacti O. imbricata, all plants contained Fe levels in substantial amounts to meet adult range ruminant requirements (45 mg of Fe kg⁻¹ of diet DM for beef cattle, sheep, goats and white tailed deer, respectively; NRC 2000, 2007). Similar findings were reported by Ramírez-Orduña et al. (2005) and Ramírez-Lozano et al. (2010) who evaluated the Fe contained in native forages that grow in semiarid regions of Mexico. They sustained that Mexican browse species had Fe levels in substantial amounts to meet the Fe requirements of adult range small ruminants. Iron deficiency seldom occurs in browsing and grazing ruminants due to generally adequate pasture concentrations and contaminants of plants by soil. Soil contamination of forages and direct soil consumption often provide excess quantities of dietary Fe (McDowell 2003).

Manganese content was higher in the group of plants of flowers, fruits and pods (range = 8–888 mg kg⁻¹ DM) followed by cacti (141–171), forbs (47–82), trees (48–63) and shrubs (24–84). Except for the shrub Caliandra eriophylla, all plants had Mn concentrations to meet the requirements of adult range ruminants (30 mg of Mn kg⁻¹ of diet DM for beef cattle, sheep, goats and white tailed deer, respectively; NRC 2000, 2007). Low Mn levels, in dry seasons, of native shrubs and trees growing in different rangelands of Mexico were also reported by Cerrillo-Soto et al. (2004), Ramírez-Orduña et al. (2005) and Ramírez-Lozano et al. (2010).

Zinc content was higher in forbs (range = 24–64 mg kg⁻¹ DM) followed by flowers, fruits and pods (17–109), cacti (13–89), shrubs (17–71) and trees (16–17). In this study, only shrubs such as A. canescens, C. pallida, L. tridentata and A. shaffneri; the forb D. bicolor; the cacti O. leptocaulis, and the flowers of Yucca spp. and O. leptocaulis and the pods of A. shaffneri had sufficient levels of Zn to meet goat requirements (35, 27, 45 and 45 mg of Zn kg⁻¹ of diet DM for beef cattle, sheep, goats and white tailed deer respectively; NRC 2000, 2007). Some shrubs that occur northeastern Mexico (Ramírez-Lozano et al. 2010) and African rangelands (Kabasa et al. 2004; Aganga and Mesho 2008) also had low levels of Zn to meet domestic and white-tailed deer requirements. Conversely, Cerrillo-Soto et al. (2004) and Ramírez-Orduña et al. (2005) indicated a relevant potential mineral intake of Zn by range Spanish goats browsing in north and northwestern regions of Mexico.

It is concluded that only Ca, Mg, K, Fe and Mn, in most plants, were in sufficient amounts to satisfy range ruminant requirements for these minerals, thus range ruminants consuming these plants may receive supplementation by P, Na, Cu and Zn that were lower in most evaluated plants.

Acknowledgements

We would like to Consejo Nacional de Ciencia y Tecnología, Mexico for providing a Doctoral Scholarship to Maribel Guerrero-Cervantes.