Evaluation of promissory tree species for sheep feeding in The Highlands of Chiapas, Mexico

Evaluation of promissory tree species for sheep feeding in The Highlands of Chiapas, Mexico

Animal Feed Science and Technology 73 (1998) 59±69 Evaluation of promissory tree species for sheep feeding in The Highlands of Chiapas, Mexico J. Nah...

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Animal Feed Science and Technology 73 (1998) 59±69

Evaluation of promissory tree species for sheep feeding in The Highlands of Chiapas, Mexico J. Naheda,*, A. SaÂncheza, D. Grandeb, F. PeÂrez-Gilc a

El Colegio de la Frontera Sur, DivisioÂn de Sistemas de ProduccioÂn, Carretera Panamericana y PerifeÂrico sur s/n, CP 29290 San CristoÂbal de Las Casas, Chiapas, Mexico b Universidad AutoÂnoma Metropolitana Iztapalapa, Area de Sistemas de ProduccioÂn Animal, Av. MichoacaÂn y La PurõÂsima Col. Vicentina, Iztapalapa, CP 09340, MeÂxico, D.F., Mexico c Instituto Nacional de la NutricioÂn Salvador ZubiraÂn, Departamento de NutricioÂn Animal, Vasco de Quiroga No. 15 Col. y DelegacioÂn Tlalpan, CP 14000, MeÂxico, D.F., Mexico Received 15 January 1997; accepted 24 December 1997

Abstract The main objective of this study consisted of evaluating the fodder potential of the foliage of Buddleia cordata, Montanoa leucantha subsp. arborescens, Erythrina chiapasana, Quercus rugosa and Alnus acuminata var. arguta, tree species present in The Highlands of Chiapas, Mexico, in order to select the best fodder and carry out an evaluation of the species with greatest potential in sheep feeding. The chemical composition results on a dry matter basis were as follows: the crude protein (CP) content ranged from 8.4% in Q. rugosa to 27.7% in M. leucantha. Neutral detergent fiber (NDF) ranged from 39.0% in M. leucantha to 58.3% in Q. rugosa and Acid detergent fiber (ADF) varied from 30.8% in M. leucantha to 56.8% in Q. rugosa; Gross energy (GE) contents were 3.0 kcal/g or even greater. Tannic acid was detected from 0.25 g/100 g in E. chiapasana to 1.1 g/ 100 g in Q. rugosa; there were no cyanogenic glucosides detected in the samples, and no alkaloids were encountered in Q. rugosa and A. acuminata, but E. chiapasana showed higher alkaloid content than the other trees. Q. rugosa had the highest foliage production (6.9 kg DM/plant/cut), while E. chiapasana had the lowest production (1.2 kg DM/plant/cut). In an in vivo intake and digestibility trial, the leaves of M. leucantha fed as a sole diet for sheep had the best composition values, higher (P<0.05) in vivo dry matter intake (IVDMI-L) (628 g/day) and in vivo dry matter digestibility (IVDMD-L) (76%) of the five evaluated species. Therefore, the foliage of M. leucantha was included in the sheep's diet in a growth and digestion trial at 0%, 25% and 40% levels of inclusion replacing alfalfa (M. sativa); in vivo CP intake (IVCPI-D) (106.9 g/day), in vivo CP digestibility (IVCPD-D) (67.5%), and live weight gain (LWG) (75 g/day) were higher (P<0.05) in sheep fed with diets including M. leucantha leaves at 40% level of inclusion. In vivo DM intake (IVDMI-D), in vivo DE intake (IVDEI-D) and in vivo NDF intake (IVNDFI-D), as well as in vivo DM * Corresponding author. Fax: +52 967 82322; e-mail: [email protected] 0377-8401/98/$19.00 # 1998 Elsevier Science B.V. All rights reserved PII S 0 3 7 7 - 8 4 0 1 ( 9 8 ) 0 0 1 3 1 - X

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digestibility (IVDMD-D), in vivo DE digestibility (IVDED-D), in vivo NDF digestibility (IVNDFD-D) and wool production (WP), were similar (P>0.05) in diets including 0%, 25% and 40% of Montanoa leucantha leaves. # 1998 Elsevier Science B.V. Keywords: Fodder trees; Sheep feeding; Highlands; Mexico

1. Introduction This research is part of a sustainable development strategy for the sheep production system carried out by the Tzotzil Indians in The Highlands of Chiapas, Mexico, where the excessive pressure due to the utilization of the natural resources, has caused their deterioration as well as a decrease in the life conditions of the population (Nahed and Parra, 1984). Paradoxically, there is a plentiful base of plant resources (Soto et al., 1988; GonzaÂlez et al., 1991) and a wide knowledge and ability of the producers about its management (Parra et al., 1993; Nahed et al., 1997). This indicate that there is a great potential in the region to develop efficient strategies for the intensification of sheep production system. The producer's strategy consist of using all the forage resources they have, including foliage from tree and shrub species, in order to complement the diet of grazing sheep, especially during drought. Although the producers of the zone know the fodder potential of the woody species, problems such as the extensive deforestation, the intensive use of the soil, and the severe lack of forage in the drought season, have provoked the necessity of making investigations in order to select those species that have a greater potential and economic importance as well (Borel, 1990; Devendra, 1990), with the purpose of studying them in detail, and planning to incorporate them systematically into the actual sheep production. In this sense, the objective of this study was to evaluate the fodder potential of the foliage of five woody species: Buddleia cordata H.B.K, Montanoa leucantha subsp. arborescens (D.C.) V.A Funk, Erythrina chiapasana Krukoff, Quercus rugosa Nee, and Alnus acuminata var. arguta Schlecht. All of them are used with a great deal of frequency in sheep feeding by the producers of The Highlands of Chiapas. The main purpose was to select the best of them and to continue its evaluation in sheep feeding. Such species have also been used as animal feed in other areas (Araya et al., 1994; Mendizabal et al., 1994; Camacho et al., 1996) 2. Materials and methods The research was carried out in The Highlands of Chiapas, Southern Mexico (93880 , 938550 W; 168300 , 168550 N), within an area covering 3456.5 km2. The average altitude is 2300 m above sea level; the climate is temperate subhumid, C(W2) (W), according to Koepen's classification, modified by GarcõÂa (1988), with an average annual temperature of 11±168C and average annual rainfall of 1100±1300 mm. The foliage evaluation of

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B. cordata, M. leucantha subsp. arborescens, E. chiapasana, Q. rugosa and A. acuminata var. arguta was choosen because they are species frequently utilized in sheep feeding by the producers of the zone. 2.1. Phase 1: Fodder potential of five tree species 2.1.1. Nutritional, chemical and toxicological analysis A sample composed of the foliage (leaves including petioles) of each one of the studied species, was obtained from the lower and medium layers of the tree tops (in vegetative stage), in order to determine: dry matter (DM) and crude protein (CP) according to established methods of the AOAC (1980); gross energy (GE) according to Bateman (1970); neutral detergent fiber (NDF) and acid detergent fiber (ADF) with the Van Soest et al. (1991) method; the presence of alkaloids (ALK) (qualitative determination) and tannic acid (TA) were evaluated using the DomõÂnguez (1979) technique, and cyanogenic glucosides (CG) through a qualitative technique according to AOAC (1980). 2.1.2. Foliage production Foliage production was evaluated considering five trees of each one of the selected species; they were selected at random throughout the field. All trees were young growth plants in vegetative stage; only A. acuminata included trees in fructification stage. In order to obtain all the foliage, the cut included the leaves and petioles in a single cutting. The leaves and petioles were harvested during the months of November and December of 1995. The height mean of the studied species were 4.5, 10.1, 9.2, 5.2 and 12.7 m for M. leucantha, B. cordata, Q. rugosa, E. chiapasana and A. acuminata, respectively. The stem's diameter for the species at the breast level were among 0.17±0.27 m. 2.1.3. Intake and digestibility trial The objective of this trial consisted in evaluating leaves intake and their digestibility of each one of the five woody species offered as a sole feed source to the sheep's ration. This trial was carried out with three criollo male sheep, 1 year old, with an average initial live weight (ILW) of 22±23 kg. The animals were placed in metabolic crates and had free access to a diet of exclusively green foliage (leaves with petiole) of each one of the five studied species. The ovines had a previous period of adaptation of ten days and a ten-days evaluation period; every time they consumed each one of the five species samples, bearing in mind that for a sheep, a 5 day period is sufficient for securing accuracy of intake prediction (Ben Salem et al., 1994). During the evaluation period, the animals had a feed restriction of 10% of the intake of the previous period for accuracy of leave's intake. The in vivo dry matter intake of leaves (IVDMI-L) was measured based on the difference between the offered and the refused feed, and at the same time, the in vivo dry matter digestibility of leaves (IVDMD-L) was determined by the Harris (1970) method. The experimental arrangement was a randomized design in which each forage species was considered as a treatment with three repetitions every time. The data were analyzed through an analysis of variance, taking the ILW of the sheep as a co-variable.

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The mean comparison test was realized by means of the Tukey test at a significance level of P<0.05 (Steel and Torrie, 1985). 2.2. Phase II: Biological response of sheep fed with diets including leaves from Montanoa leucantha subsp. arborescens The objective of this trial was to evaluate the LWG, WP and the in vivo intake and digestibility of diets containing two levels (25% or 40%) of leaves of Montanoa leucantha subsp. arborescens offered to the sheep. This evaluation was carried out with twelve criollo male sheep, with an initial live weight of 16.8‡1.6 kg. The animals were placed in individual metabolic crates. The experiment had a randomized design with three treatments and four repetitions per treatment resulting, in four observations per treatment. The diets were as follows: T1ˆ25% M. leucantha‡32% corn stubble‡42% molasses‡1.4% of urea; T2ˆ40% M. leucantha‡30% corn stubble‡30% molasses; and T3ˆ40% alfalfa‡30.6% corn stubble‡28.1% molasses‡1.2% of urea. Table 1Table 2 show the chemical composition of the ingredients used in diet formulation and the nutrient content of the experimental diets. Sheep were adjusted to the diets during a 2 weeks preliminary period, having had a previous ten-day adaptation period. This was followed by a 12 weeks data collection period. During the evaluation period, the animal had a feed restriction of 10% of the intake of the previous period for accuracy of the diet's intake. At the end of the preliminary 2 weeks period the sheep were sheared to evaluate the WP during the trial. The in vivo dry matter intake (IVDMI-D), crude protein intake (IVCPI-D), digestible energy intake (IVDEI-D) and neutral detergent fiber intake (IVNDFI-D) of the diets were evaluated. On the other hand, in vivo dry matter digestibility (IVDMD-D), crude protein digestibility (IVCPD-D), digestible energy digestibility (IVDED-D) and neutral detergent fiber digestibility of the diets (IVNDFD-D) were also evaluated. Table 1 Chemical composition of the ingredients used in diet formulation (% on a dry basis) Ingredients

DM (%)

CP (%)

GE (kcal/100 g)

NDF (%)

M. leucantha leaves Alfalfa Corn stubble Molasses Urea

90.0 90.0 92.0 75.0 90.0

28.0 19.4 3.0 Ð 28.7

318 360 317 489 Ð

44.72 41.2 75.6 Ð Ð

GEˆGross energy Table 2 Nutrient content of the experimental diets Nutrient M. leucantha (%) Protein (%) GE (kcal/100 g)

Treatment 1 25

2 40

3 0

11.9 341

12.1 331

12.1 340

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The intake and digestibility of the diets were determined according to Harris (1970) methodology. The LWG was registered every 15 days. The treatment effects were examined statistically through the analysis of variance taking the ILW, DMI and the initial length of the wool as co-variables (Steel and Torrie, 1985). 3. Results and discussion 3.1. Phase 1: Fodder potential of five tree species 3.1.1. Nutritional, chemical and toxicological analysis The results of the nutritional, chemical and toxicological analysis of the foliage of the studied species are shown in Table 3. Q. rugosa showed a greater content of DM than the other species. M. leucantha and B. cordata were outstanding for their high contents of CP, acceptable concentration of GE, NDF and ADF, as well as their low or almost nonexistent level of toxic substances. In order of importance these species were followed by E. chiapasana, based on its nutrient content; however this species had the disadvantage of containing high levels of NDF, ADF, TA and ALK, and it was followed in the same order by Q. rugosa. As a whole, all the species showed similar or better chemical composition than the tree and shrub foliages reported by Benavides (1991) and that of the naturalized grasses of the region (Urquijo et al., 1991), and a better quality in comparison to types of straw and stubble usually used for sheep feeding by the producers of the zone. Lowry (1990) reported low toxic compounds in some shrub and tree species, which is in agreement with the results obtained in this study for the ALK, CG and TA contents of the foliages studied for ruminants. 3.1.2. Foliage production In Fig. 1 the average foliage production of the five forage trees are shown. Q. rugosa with 6.9 kg of DM per plant and per cutting produced a greater quantity followed by B. cordata with 5.9 kg, and A. acuminata with 5 kg. M. leucantha (1.7 kg DM/plant/cut), and E. chiapasana (1.2 kg DM/plant/cut) showed the least production of foliage. The first Table 3 Chemical composition of the foliage of woody species (vegetative stage) during the rainy season in The Highlands of Chiapas, Mexico (% DM) Tree species

DM (%)

CP (%)

GE (kcal/100 g)

NDF (%)

ADF (%)

TA (g/100 g)

ALK a

CG a

M. leucantha B. cordata E. chiapasana Q. rugosa A. acuminata

26.6 35.8 27.6 53.0 40.0

27.7 18.1 17.8 8.4 17.8

340 350 340 300 420

39.0 49.2 57.3 58.3 57.3

30.8 38.6 40.2 56.8 48.5

0.42 0.41 0.25 1.16 0.91

Sc. Sc. Abund. Neg. Neg.

Neg. Neg. Neg. Neg. Neg.

DMˆDry matter; CPˆCrude protein; GEˆGross energy; NDFˆNeutral detergent fiber; ADFˆAcid detergent fiber; TAˆTannic acid; ALKˆAlkaloids and CGˆCyanogenic glucosides. a Qualitative evaluation; Abund.ˆAbundant; Sc.ˆScarce; Neg.ˆNegative or no detected.

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Fig. 1. Mean foliage production of five woody species of The Highlands of Chiapas, Mexico (nˆ5): (1) Montanoa leucantha subsp. arborescens, (2) Buddleia cordata, (3) Erythrina chiapasana, (4) Alnus acuminata var. arguta and (5) Quercus rugosa. a,b,cˆBars with a different letter are statistically different (P<0.001).

three species produced more foliage per cutting in a total harvest than the four forage trees reported by Pineda (1988), while the two other species showed a lower production. 3.1.3. Sheep intake and digestibility of leaves trial Table 4 shows the average of the IVDMI-L and IVDMD-L of the foliage of the five woody species studied and offered as a sole diet to sheep. Of the five species, the leaves of M. leucantha were (P<0.001) the most consumed by the animals, followed by E. Table 4 In vivo dry matter intake (IVDMI-L) and in vivo dry matter digestibility (IVDMD-L) of leaves of woody species fed to sheep (nˆ3) as a sole diet Tree species

IVDMI-L Observed (g dÿ1)

DMI Estimated * (g dÿ1)

IVDMD-L Observed (%)

M. leucantha B. cordata E. chiapasana Q. rugosa A. acuminata

SE 628.4c88.1 317.7b15.8 370.8b43.3 296.2b18.3 56.6a6.9

1036.5 1019.2 873.8 938.6 1001.0

76.2c 82.5c 39.4ab 55.7bc 22.4a

*

SE 1.7 3.6 4.1 2.4 6.5

Estimation based only on the metabolic body weight of the animals (NRC, 1985); IVDMI-LˆIn vivo Dry matter intake of leaves; IVDMD-LˆIn vivo dry matter digestibility of leaves. a,b,cˆMeans with distinct letters in the same column are different (P<0.001).

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chiapasana, B. cordata and Q. rugosa, while A. acuminata was the least consumed. The high intake of M. leucantha foliage was related with the high CP content and low concentration of NDF and ADF. As a whole, the IVDMI-L in all the species was lower than that required by sheep according to their metabolic weight (NRC, 1985). In some cases the results of the IVDMI-L were similar or inferior to those obtained by Pineda (1988), Saha and Gupta (1987) and Larbi et al. (1993), who evaluated different woody species. The greater IVDMD-L was observed for B. cordata, followed by M. leucantha and Q. rugosa; B. cordata, M. leucantha and Q. rugosa did not show any differences in regard to their digestibility. The relative higher digestibility of B. cordata was supported by its low intake as a result of its higher DM content (about 50% more) than M. leucantha. This would mean that B. cordata was exposed for more time to the action of the ruminal microorganisms with a higher digestibility. On the other hand, the high moisture content of M. leucantha probably favored a less retention time of the feed in the rumen; therefore, although M. leucantha had less NDF and ADF content, its digestibility was smaller due to that the animals ate almost double on a DM basis. E. chiapasana and A. acuminata had very low digestibilities and this can be related to a number of different factors such as a high content of fiber fractions, or the presence of toxic substances; the low digestibility of E. chiapasana was due to the high NDF and ALK contents; the very low digestibility of A. acuminata was related to the high NDF, ADF and TA contents. Similar observations have been reported by Saha and Gupta (1987). 3.2. Phase II. Biological response of sheep fed with diets containing Montanoa leucantha subsp. arborescens leaves Table 5 shows the results of the biological response of sheep fed with diets which included two levels of foliage from M. leucantha. It was observed that the IVDMI-D in the different treatments were higher to that required according to the metabolic weight of the sheep. The results of the IVDMI-D were greater and the LWG lower than those reported by Benavides (1991) in sheep fed with King grass (P. purpureum) and supplemented with several levels of white mulberry foliage (Morus sp.). It is interesting to observe that the CP intake and digestibility, as well as the LWG, were greater (P<0.05) in the diet with 40% M. leucantha. On the other hand, the DM, DE and NDF intake and digestibility, like WP showed no differences in diets with 0%, 25% and 40% M. leucantha. In general, the response of the animals to the diets offered was low, especially in Tl. This was probably due to the fact that at least one part of the protein in the food allowance was not available due to the low quality of the corn stubble; it is possible that this reduced the global utility of the feed consumed (Nahed et al., 1991). On the other hand, the animals that had eaten, had a low energy intake due principally for the high content of corn stubble in the diet. It was observed a tendency for a higher clean wool production in T3, but with a lower length than T1 and T2. This could be explained due to a better quality protein in the diet

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Table 5 Biological evaluation of diets containing two levels of leaves of Montanoa leucantha subsp. arborescens by sheep (nˆ4), in The Highlands of Chiapas, Mexico Concept

Treatment

M. leucantha (%)

1 25

2 40

3 0

SE

SE

SE

950.0a61.2 92.8a6.7 1.93a0.10 685.6a38.7

1048.0a45.1 106.9b4.5 1.96a0.12 690.0a55.0

978.0a55.4 93.3a6.2 1.68a0.11 612.4a33.4

Digestibility DM (%) CP (%) DE (%) NDF (%)

68.0a0.98 52.3a2.4 58.9a2.7 78.3a3.4

68.6a0.97 67.5b2.05 63.9a2.5 70.2a3.2

68.5a1.1 53.0a2.6 60.3a2.8 76.1a3.9

Live weight gain (g dayÿ1)

37.0a6.1

75.3c8.9

46.5ab6.6

455.3a40.2 327.5a31.5

472.0a53.8 355.5a46.6

530.5a61.3 381.5a43.7

4.0a0.4

4.9a0.5

3.8a0.3

Intake DM (g dayÿ1) CP (g dayÿ1 ) DE (Mcal dayÿ1) NDF (g dayÿ1)

Wool production (g) Dirty Clean Wool growth (cm)

T1ˆ25% M. leucantha‡32% corn stubble‡42% molasses‡1.4% urea; T2ˆ40% M. leucantha‡30% corn stubble‡30% molasses; and T3ˆ40% alfalfa‡30.6% corn stubble‡28.1% molasses‡1.2% urea. a,b,cˆDifferent letters in the same row are statistically different (P<0.05).

with 40% alfalfa, associated with a higher essential sulfur amino acids content in this forage. In contrast, the best IVPCI-D in T2 favoured the tendency for a higher wool growth of poor quality and on the other hand, a higher meat production that provoked a higher LWG of the animals. In a review, Allden (1979) has shown that 77% of the variance in wool growth rate on sheep grazing, a range of stocking rates from several years data of Cannon (1969), was accounted for the metabolic live weight (L0.75, kg 0.75) and live weight change (C, g/day). However, he concluded that despite the poor consistency in the many reported relationships between wool growth and the intake of sheep, wool growth is determined mainly by the amount of feed consumed by the animal. Reasons for inconsistencies were suggested as natural seasonal rhythm, decreasing digestibility of the diet as intake increases, time lag in the development of the dermal papilla in the wool follicle when intake changes or through competition for available metabolites between different physiological responses including the wool follicle when the weight of the animal is changing. The nutritional responses of wool growth are well documented. Post ruminal administration of casein or the essential sulfur amino acids has been shown by Reis and Schinckel (1963), Reis (1969, 1979) to increase wool growth, while Black et al. (1973) have demonstrated that the ratio of protein to energy is important with either too

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little or too much of restricting wool growth. The feeding frequency of wheat (weekly versus daily) (Franklin and Sutton, 1952) and hay (weekly versus daily versus thrice daily) (Birrel and Bishop, 1970) has been shown to influence wool growth with increased responses with infrequent feeding. 4. Conclusions Because of its high nutrient content, low concentration of toxic substances, and high intake and digestibility, the foliage of M. leucantha was the most recommended of the five evaluated species for incorporation into the regional sheep production system. The inclusion of 40% of this foliage in the total sheep diet, produced the best utilization of the feed and weight gain. Q. rugosa and B. cordata have the potential to resolve the nutritional challenges of the animals in the zone due to their high biomass production. Of these two species, B. cordata represents the best option due to its high protein content, an acceptable intake by sheep, and for having the highest in vivo digestibility among the five evaluated species. Agronomical tests and animal response evaluations in sheep grazing supplemented with foliage of M. leucantha, B. cordata, Q. rugosa and E. chiapasana are required in order to observe their effects on the productivity and the sustentability of the pasture. As a result of this, it will be possible to produce complementary information that would permit planning of a systematic incorporation of the tree and shrub species in sheep production of the region. Acknowledgements The authors are thankful to Susana Ochoa, Angel MartõÂnez, Luis Villafuerte, Kristen Nelson and the cooperant producers from The Highlands of Chiapas for helping in the realization of this research. They also thank the National Council of Science and Technology of Mexico (especially Dr. Mario Gonzalez, Project Leader) and Rockefeller Foundation (especially, Dr. Manuel Parra, Project Leader) for their financial support. To Ruth Pealing, participant in the CONACYT-BRITISH COUNCIL Exchange Programme for helping in the translation and revisions of the manuscript. References Allden, W.G., 1979. Feed intake, diet composition and wool growth. In: Black, J.L., Reis, P.J. (Eds.), Physiological and Environmental Limitations to Wool Production. University of New England Publishing, Unit Armidale, pp. 61±78. AOAC, 1980. Official Methods of Analysis of the Association of Official Analytical Chemists, 15th Ed., Association of Official Analytical Chemists, Washington, DC, USA. Araya, J., Benavides, J.E, Arias, R., RuõÂz, A., 1994. IdentificacioÂn y caracterizacioÂn de aÂrboles y arbustos con potencial forrajero en Puriscal, Costa Rica. In: Benavides, J.E. (Ed.), Arboles y Arbustos Forrajeros en

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