Livestock Research for Rural Development 16 (4) 2004

Citation of this paper

In vitro gas production parameters in cacti and tree species commonly consumed by grazing goats in a semiarid region of North Mexico

M A Cerrillo and R A S Juárez

Facultad de Medicina Veterinaria y Zootecnia. División de Estudios de Posgrado. Universidad Juárez del Estado de Durango. Carretera Durango-Mezquital km 11.5. Durango, Dgo. México
acerrillos@terra.com.mx


Abstract

The objective of this study was to characterize the in vitro gas production of Encino blanco (Quercus grisea), Encino colorado (Quercus eduardii), huisache (Acacia shaffneri), cardenche (Opuntia imbricata), tasajillo (Opuntia leptocaulis) and nopal (Opuntia, spp) with the aim of identifying relationships between in vitro gas production and chemical composition. Crude protein (CP), Neutral detergent fiber (NDF), Acid detergent fiber (ADF), cellulose, hemicellulose and lignin analyses of the species were performed before the determination of in vitro gas production. The samples (200 mg OM) were incubated in glass syringes with rumen fluid obtained from three goats fed alfalfa hay. The gas volume was recorded at 0, 3, 6, 9, 12, 24, 48, 72 and 96h post-inoculation and the data fitted to the model P = a + b (1 - e-ct). The model parameters were estimated using PROC NLIN (SAS) and the resulting data analyzed using a completely randomized experimental design using ANOVA PROC GLM. Tukey´s test was used to determine differences between means.

Acacia shaffneri had the highest (P<0.05) CP level (117g/kg DM); the Quercus had intermediate values (72 and 64g/kg for Quercus grisea and Quercus eduardii, respectively), and the cacti species the lowest values (34g/kg CP). NDF content ranged from 337g/kg in the nopal to 631g/kg in the Quercus species. NDF in Opuntia imbricata (513g/kg) was characterized by a high hemicellulose content (365g/kg). The lignin was greater (P<0.05) in tree leaves (176g/kg), while the cacti generally had low lignin contents (11 to 44g/kg). The cumulative gas release at 96 h was nearly 53 ml/200 mg OM for Opuntia leptocaulis, whereas Quercus eduardii produced 34 ml/200 mg OM. No differences (P> 0.05) were registered for the gas derived from the (a) fraction. The highest gas volume originated from the (b) fraction was found with Opuntia leptocaulis (P<0.05) (45.6 ml/200 mg OM). Quercus eduardii produced the lowest value for this fraction (26.3 ml/200 mg OM). The highest constant rate of gas production (c) was registered in Opuntia spp (11.6 % h-1) whereas the lowest constant rate was registered in Quercus grisea (1.97 % h-1). The potential production (a + b) ranged from 31.6 to 52.6 ml/200 mg OM (P<0.05) in Quercus eduardii and Opuntia leptocaulis, respectively. The correlations between in vitro gas production and the chemical composition of the forages were mostly negative. Significant correlations were observed with the chemical fractions related to the cell wall content: NDF: r = -0.73; ADF: r = -0.90 and lignin: r = 0.96. The in vitro gas production data and the fermentation parameters indicated a potentially high energy available in cacti species which could explain the relevance of those species in the nutrition of grazing goats in semi-arid regions.

Keywords: cacti, fermentation parameters, gas production, goats, shrubs.


Introduction

The relevance of evaluating the nutritional value of shrubs, trees and cactus is evident (Ramirez et al 2000a; Nherera et al 1999; Topps 1992) as their foliage makes an important contribution to the protein and energy consumption of browsing ruminants . This is particularly important in arid and semi arid regions where forage availability and quality may be severely limited during the dry season (Papachristou 1996; Degen et al 1997). Native vegetative species such as huisache (Acacia shaffneri), encino blanco (Quercus grisea), encino colorado (Quercus eduardii), cardenche (Opuntia imbricata), tasajillo (Opuntia leptocaulis) and nopal (Opuntia spp) are widely distributed in the semi arid regions of North Mexico and constitute a significant part of the diet consumed by grazing goats (Juárez et al 1998). However, scarce information is available on their digestible and fermentative characteristics as an indication of their nutritional value. The in vitro gas production technique is a useful tool to determine the nutritional value of the forages consumed by ruminants (Blümmel and Becker 1997) assuming that the volume of gas produced reflects the end result of the fermentation of the substrate to VFA, microbial biomass and neutralization of the VFA. In addition, the application of models permits the fermentation kinetics of the soluble and readily degradable fraction of the feeds, and the more slowly degradable fraction to be described (Gatechew et al 1998). Moreover, the gas production parameters of shrubs, trees and cactuces might demonstrate differences in their nutritional value that may be closely related to their chemical composition.

The objective of this study was to estimate in vitro gas production and its correlation to the chemical composition of browse species consumed by grazing goats in a semiarid region of North Mexico.


Material and methods

The study was conducted at the Facultad de Medicina Veterinaria y Zootecnia de la Universidad Juarez del Estado de Durango, Mexico, located between 22° 22´and 26° 50´ North latitude and 102° 25´ 55´´ and 107° 88´ 55´´ West longitude. The geographic area is characterized by climate BS1 (w)(e) (dry temperate), with a mean annual rainfall of 450 mm and mean temperature of 17°C.

Leaves of encino blanco (Quercus grisea), encino colorado (Quercus eduardii), huisache (Acacia shaffneri), cardenche (Opuntia imbricata), tasajillo (Opuntia leptocaulis) and immature pods of nopal (Opuntia spp.) were collected. The samples were dried at ambient temperature. The cacti pods were burned and chopped which is a standard practice performed by the farmers in the field. The samples were ground to pass a 1 mm sieve.

Chemical analyses of forages

Neutral detergent fiber (NDF), acid detergent fiber (ADF) and lignin analysis of the substrates were conducted according to Van Soest et al (1991). Crude protein (CP) and ash were determined according to standard procedures (AOAC 1990).

In vitro gas production

In vitro gas production evaluation was determined following the method of Menke and Steingass (1988). About 200 mg of OM sample in three replicates were placed into 100 ml glass gas syringes (Haberle Labortechnik, Germany). Rumen fluid was obtained from three fistulated goats (Hecker 1969) fed alfalfa hay (2.5% BW) twice a day. The inoculum was mixed with a sodium and ammonia bicarbonate buffer (35 g NaHCO3 plus 4 g NH4HCO3 per litre) in a ratio of 1:2 (v/v). Thirty ml buffered inoculum was added to each syringe and excess gas released. The syringes were positioned vertically in a water bath kept at 39°C. Two blank syringes containing 30 ml of the medium only were also included. All the syringes were gently shaken 30 min after the start of the incubation and thereafter four times daily. Gas production was recorded at 0, 3, 6, 9, 12, 24, 48, 72 and 96 hours of incubation. The data were fitted to the exponential equation: p = a + b (1 - e -ct) (Ørskov and McDonald 1979), where p represents gas volume at time t, a the gas produced from the soluble fraction, b the gas produced from the insoluble but fermentable fraction, a+b the potential gas production, and c the rate constant of gas production during incubation (% h-1). The parameters were estimated using PROC NLIN (SAS 1997). The data were analyzed using analysis of variance for a completely randomized experimental design by PROC GLM (SAS,1997). Mean comparisons were performed using Tukey´s test (Hicks and Turner 1999).


Results and discussion

Chemical composition of forages

The highest CP content (P<0.05) was observed for A. Schaffnerii (117g/kg) (Table 1). Quercus showed intermediate values (72 and 64g/kg for Quercus grisea and Quercus eduardii, respectively), while the lowest CP content was found with cacti (33g/kg). The CP in Acacia shaffneri (117 g/kg) is lower than the CP content registered in other shrub areas in the semi-arid region of North Mexico (200 g/kg, Ramirez and Ledesma-Torres 1997; 167g/kg, INIP 1977) but similar to A. catechu (130g/kg) and A. nilotica (139g/kg) (Mandal 1997). In cacti, the CP content in this study (35g/kg) is similar to Nopalea cochinellifera (43g/kg) (INIP 1977) but different from O. leucotrichia (75g/kg) (INIF 1981). The CP content in leaves from shrubs and trees is high compared to grasses, thus such species are preferred by grazing goats and are a good source of protein and minerals (Ramirez et al 2000b).

Table 1. Chemical composition of the evaluated vegetative species, g/kg DM

Species

DM

Ash

CP

NDF

ADF

Cellulose

Hemicellulose

Lignin

Quercus grisea

938b

48.0e

72.3b

631a

425b

283a

206cd

141b

Quercus eduardii

939b

30.3f

64.0c

629a

463a

270a

166ed

193a

Acacia shaffneri

946a

71.6d

117a

568b

330c

136b

238cb

194a

Opuntia spp

931c

228c

33.3d

337e

201d

157b

136e

44.3c

Opuntia imbricata

930c

301a

33.3d

513c

147e

137b

365a

11.3d

Opuntia leptocaulis

940b

233b

34.3d

448d

164e

142b

284b

21.3d

abcdef Means within columns without common superscript differ at P<0.05.

The NDF content varies among species: 390g/kg for A. farnesiana (Ramirez and Ledesma-Torres 1997), 530g/kg for A. catechu (Mandal 1997) and 640 g/kg for Q. semecarpofilea (Singh et al 1999). In cacti species in the present study, the NDF values were lower (340 g/kg) than those reported earlier by Ramirez et al (2000a) (370 g/kg). Similarly, ADF values in Quercus from this study were lower than the ADF content reported by Singh et al (1999) (510 g/kg) and Mandal (1997) (350 g/kg); however, such variations are considered to be due to differences among species. The low cellulose content (137 g/kg) and lignin (11 g/kg) in Opuntia imbricata indicates a readily degradable energy source and a strategic vegetative species for animal survival in semi-arid areas. Other researchers have reported a high IVOMD (67%) and energy content (2.2 Mcal/kg DM) (Gutierrez and Garcia 1998; Ramirez et al 2000) in this kind of vegetative species, again suggesting the potential of this feed for range goats during the dry season (Ricardi and Shimada 1992).

Cumulative gas production

Differences were observed between species (Figure 1). The higher value (52.6 ml/200 mg OM) was registered for Opuntia leptocaulis while the lower gas release (33.1 ml/200 mg OM) was for Quercus eduardii. Results obtained in this study are similar to those reported by Keir et al 1997 and Ly et al 1997 in leaves from tropical trees and shrubs.

Figure 1. Cumulative gas release of the studied vegetative species.

Figure 2. Cumulative gas release of trees and cacti.

Fermentation parameters of forages

Fermentation parameters from the evaluated species derived by fitting the equation P= a+b (1 - e-ct) are presented in Table 2. The gas volume obtained from the soluble fraction (a) was similar (P>0.05) for all the species. The fermentation of the insoluble but degradable fraction (b) produced more gas (P<0.05) in cacti species (45.6, 39.8 and 38.1 ml/200 mg OM) for Opuntia leptocaulis, Opuntia spp, and Opuntia imbricata, respectively) and the gas produced was statistically different among them (P<0.05). The lowest value was registered for Quercus eduardii (26.3 ml/200 mg OM). The rate of gas production (c) was higher (P<0.05) in the cacti species (Opuntia spp = 11 % h-1, Opuntia imbricata = 6.87 % h-1 and Opuntia leptocaulis = 5.40 % h-1) whereas the lowest value for this fraction was observed in Quercus grisea (1.97 % h-1).

Table 2. Fermentation parameters of the evaluated species (defined by the equation : P = a + b (1 – e -ct)

Fraction

Quercus

Acacia schaffneri

Opuntia

SEM

grisea

eduardii

spp

imbricata

leptocaulis

a 1

7.66a

5.29a

6.01a

4.97a

8.72a

6.97a

1.80

b 2

34.0bc

26.3d

29.1dc

39.8ba

38.1b

45.6a

2.23

c 3

1.97d

5.56cb

3.79cd

11.6a

6.87b

5.40cb

0.08

a + b 4

41.7c

31.6d

35.1d

44.8cb

46.8b

52.6a

1.16

1 = gas produced from the soluble fraction (ml/200 mg OM).
2 = gas produced from insoluble but fermentable fraction (ml/200 mg OM)
3 = rate constant of gas production during incubation (% h-1)
4 = potential gas production (ml/200 mg OM).
abcd Means within the same row without common superscript differ at P<0.05
SEM = standard error of the mean

Similarly, the extent (a + b) of gas volumes was higher for cacti than for trees.  Khazaal et al (1995) indicated that the intake of a feed is mostly explained by the rate of gas production (c) which affects the rate of passage of the feed through the rumen, whereas the potential gas production (a + b), is associated with the degradability of the feed. Thus, the higher values obtained for the (c) and (a + b) parameters in the cacti species, may indicate a better nutrient availability for rumen microorganisms in animals grazing such vegetative species in semi-arid areas.

Correlations between cumulative in vitro gas production and chemical composition of forages

There was a close negative relationship between the in vitro gas production parameters and chemical composition, except for hemicellulose which was positive (Table 3).

Table 3. Correlation coefficients between cumulative gas production and chemical composition of the evaluated vegetative species

Chemical fraction, % DM

Equation

r

SEM

CP

53.6 – 1.89 CP

-0.78**

4.8

NDF

69.3 – 0.51 NDF

-0.73**

5.3

ADF

57.7  – 0.53 ADF

-0.90**

3.3

Cellulose

55.3 – 0.68 Cellulose

-0.59*

6.3

Hemicellulose

32.2 + 0.43 Hemicellulose

 0.46

6.9

Lignin

51.5 – 0.91 Lignin

-0.96**

2.1

The relation between the variables studied was performed by a simple linear correlation procedure with cumulative gas production as dependent variable and chemical components as independent variables. Significant correlation coefficients were obtained for CP (r = -0.78), NDF (r = -0.73), ADF (r = -0.90) and lignin (r = -0.96) which explain in 60, 53, 81 and 92%, respectively, the gas produced. According to Wolin (1960), the gas is generated from the fermentation of substrate to acetate and butyrate, and to a lesser extent to propionate. These results indicate that the gas produced from forages is related to their chemical composition. The production of gas in cacti species (49 ml/200 mg OM; lignin < 45 g/kg) was higher (P<0.05) than the gas produced by tree species (35 ml/200 mg OM; lignin > 14 g/kg) (Figure 2), which may indicate significant differences in VFA production and energy value of these forages.


Conclusions


Acknowledgements

This project was supported by the International Foundation for Science (B-2985-1). The help received from the Cerrillo-Soto family for forage collection is gratefully acknowledged. Appreciation is given to Dr. Fergus Mould as well as the reviewers from LRRD for comments to improve the manuscript.


References

AOAC 1990 15 th edition. Kenneth Helrich (Editor) USA. Volume 1 p 1930-1968.

Blümmel M and Becker K 1997 The degradability characteristics of fifty-four roughages and roughage neutral detergent fibres as described by in vitro gas production and their relationship to voluntary feed intake. British Journal of Nutrition. 77, 757-768.

Degen A A, Blanke A, Becker K, Kam M, Benjamin R W and Makkar, H P S 1997 The nutritive value of Acacia saligna and Acacia salicina for goats and sheep. Animal Science. 64, 253-259.

Gatechew G , Blümmel M, Makkar H P S and Becker K 1998 In vitro gas measuring techniques for assessment of nutritional quality of feeds: A review. Animal Feed Science and Technology. 72, 261-281.

Gutiérrez A E y García A J S 1998Consumo de energía y proteína por caprinos en un matorral mediano subespinoso y matorral mediano crasirosulifolio espinoso. (Energy and protein intake by goats grazing a thorn scrubland and low shrubland). Tesis licenciatura, UJED-FMVZ. 50 pp.

Hecker J F 1969 A simple rapid method for inserting rumen cannulae in sheep. Australian Veterinary Journal. 45, 293-294.

Hicks J and Turner K V 1999Fundamental Concepts in the Design of the Experiments. Holt, Rinehart and Winston. N.Y. 201 pp.

INIF 1981 Primera reunión nacional sobre ecología, manejo y domesticación de plantas útiles del desierto (First national meeting on ecology, management and domestication of useful desert plants) 31, 200-203.

INIP 1977 Análisis bromatológico de alimentos usados como ingredientes en nutrición animal. (Chemical analyses of feeds used in animal nutrition). suplemento 5, pp 41.

Juarez R A S, Murillo O M and Martinez V M C 1998 Composición botánica y química del forraje consumido por caprinos en matorral y bosque de encino. (Chemical and botanical composition of the forage consumed by goats in a scrubland and an oak forest). XXII Congreso Nacional de Buiatria. Acapulco. México.

Khazaal K, Dentino M T, Ribeiro J M and Orskov E R 1995 Prediction of apparent digestibility and voluntary intake of hays fed to sheep: comparison between using fibre components, in vitro digestibility or characteristics of gas production or nylon bag degradation. Animal Science. 61, 527-538

Keir B, Nguyen Van Lai, Preston T R, Orskov E R 1997 Nutritive value of leaves from tropical trees and shrubs: 1. In vitro gas production and in sacco rumen degradability. Livestock Research for Rural Development. (9) 4: http://www.cipav.org.co/lrrd/lrrd9/4/bren941.htm

Ly J, Nguyen Van Lai, Rodriguez L and Preston T R 1997 In vitro gas production and washing losses of tropical crop residues for ruminants and pigs. Livestock. Research for Rural Development. (9) 4: http://www.cipav.org.co/lrrd/lrrd9/4/ly941.htm

Mandal L 1997 Nutritive values of trees leaves of some tropical species for goats. Small Ruminant Research. 24, 95-105.

Menke K H and Steingass H 1988 Estimation of the energetic feed value obtained from chemical analysis and in vitro gas production using rumen fluid. Animal Research and Development. 28, 7-55.

Nherera F V,  Ndlovu N R and Dzowela B H 1999 Relationships between in vitro gas production characteristics, chemical composition and in vivo quality measurements in goats fed tree fodder supplements. Small Ruminant Research. 31, 117-126.

Ørskov E R and Mc Donald L 1979 The estimation of protein degradability in the rumen from incubation measurements weighted according to the rate of passage. Journal of Agricultural Science Cambridge. 92, 499-503.

Papachristou T G 1996 Intake, digestibility and nutrient utilization of oriental hornbeam and ash browse by goats and sheep. Small Ruminant Research. 23, 91-98.

Ramírez R G, Alanis-Flores G F y Nunez-Gonzalez M A 2000a Dinámica estacional de la digestión ruminal de la materia seca del nopal (Seasonal dynamics of the ruminal digestion of the dry matter of nopal). Ciencia. UANL. 3, 267-311.

Ramírez R G, Neira-Morales R R, Ledesma-Torres C A, Garibaldi-Gonzales M 2000b Ruminal digestion characteristics and effective degradability of cell wall of browse species from northeastern Mexico. Small Ruminant Research. 36, 49-55.

Ramírez R G and Ledesma-Torres RA 1997 Forage utilization from native shrubs Acacia rigidula and Acacia farnesiana by goats and sheep. Small Ruminant Research. 25, 43-50.

Ricardi C and Shimada A 1992 A note on diet selection by goats on a semi-arid temperate rangeland throughout the year. Applied Animal. Behaviour Science. 33, 239-241.

SAS 1997 SAS Institute Inc. Cary, N C. USA.445p

Singh P, Verma A K, Dass R S and Mehra U R 1999  Performance of pashmina kid goats fed oak (Quercus semecapifolia) leaves supplemented with a urea molasses mineral block. Small Ruminant Research. 31, 239-244.

Topps J H 1992 Potential, composition and use of legume shrubs and trees as fodders for livestock in the tropics. Journal of Agricultural. Science, Cambridge. 118, 1-8.

Van Soest P J, Robertson J B and Lewis B A 1991 Methods for dietary, neutral detergent fiber, and non starch polysaccharides in relation to animal nutrition. Symposium: carbohydrate methodology, metabolism, and nutritional implications in dairy cattle. Journal of Dairy Science. 74, 3583-3597.

Wolin M J 1960  A theoretical rumen fermentation balance. Journal of Dairy Science. 43,1452-1469.


Received 20 July 2003: Accepted 10 December 2003

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