- Email: [email protected]
In situ ruminal and intestinal nutrient digestibilities of mesquite (Prosopis juliflora) pods
Animal Feed Science and Technology 100 (2002) 107–112
Short communication
In situ ruminal and intestinal nutrient digestibilities of mesquite (Prosopis juliflora) pods A.M. Batista a,b , A.F. Mustafa c,∗ , J.J. McKinnon d , S. Kermasha e a
Bolsista da Coordenacao de Aperfeicoamento de Pessoal de Nivel Superior, Brasilia, DF, Brazil b Departamento de Zootecnia, Universidade Federal Rural de Pernambuco, Recife-PE, Brazil c Department of Animal Science, MacDonald Campus, McGill University, 21,111 Lakeshore Road, Ste-Anne de Bellevue, Que., Canada H9X 3V9 d Department of Animal and Poultry Science, University of Saskatchewan, Saskatoon, Sask., Canada e Department of Food Science, McGill University, Ste-Anne de Bellevue, Que., Canada H9X 3V9 Received 17 July 2001; received in revised form 8 April 2002; accepted 8 May 2002
Abstract Two steers fitted with ruminal and duodenal cannulas were used in a randomized complete block design to determine ruminal and intestinal digestibility of dry matter (DM), crude protein (CP) and neutral detergent fiber (NDF) from as collected and dried (80 ◦ C for 2 h) mesquite pods. On a DM basis, as collected mesquite pods contained 290 g kg−1 neutral detergent fibre, 172 g kg−1 acid detergent fibre, and 127 g kg−1 CP. Drying at 80 ◦ C for 2 h reduced (P < 0.05) the in situ soluble CP fraction and increased (P < 0.05) the slowly degradable CP fraction and its rate of degradation. However, ruminal degradability of both CP and DM of mesquite pods were not affected by drying. Post-ruminally digestibility of ruminal undegraded CP and NDF were low and unaffected by drying. Total tract digestibility of DM, CP and NDF were similar for as collected and dried mesquite pods, averaging 68, 78 and 9%, respectively. It was concluded that the rumen is the main site of digestion of mesquite pods and that drying at 80 ◦ C for 2 h had no adverse effects on their intestinal or total tract digestibilities. © 2002 Elsevier Science B.V. All rights reserved. Keywords: Mesquite pods; Ruminal degradability; Intestinal and total tract digestibility
1. Introduction Mesquite (Prosopis juliflora) is a leguminous tree that is native to arid and semi-arid regions of the world. The tree produces flattened, multi-seeded and curved pods with hardened pericarp. Mesquite pods are a significant feed source for livestock in many areas of the ∗ Corresponding author. Tel.: +1-514-398-7506; fax: +1-514-398-7964. E-mail address: [email protected] (A.F. Mustafa).
0377-8401/02/$ – see front matter © 2002 Elsevier Science B.V. All rights reserved. PII: S 0 3 7 7 - 8 4 0 1 ( 0 2 ) 0 0 1 3 6 - 0
108
A.M. Batista et al. / Animal Feed Science and Technology 100 (2002) 107–112
world (Riveros, 1992). Pod production per tree can vary from a few kg to over 400 kg and is highly dependent on moisture availability to the plant (Riveros, 1992). Despite the fact that mesquite pods are widely used as animal feed in many developing countries, data on their feeding value for ruminants are limited. Ibrahim and Gaili (1985) found that mesquite pods can be used as a maintenance feed for male goats when included at 60–70% of the diet DM. However, male goats fed 85 or 100% mesquite pod based diets experienced weight loss. Talpada and Shukla (1988) showed that mesquite pods can be incorporated into diets of Indian Kankrej cows at levels up to 15% of the concentrate (5% of DMI) with no adverse effects on milk production or on total tract nutrient digestibilities. In the northeast region of Brazil, mesquite trees cover 150,000 ha (Tabosa et al., 2000) and the importance of mesquite pods as a nutrient source for livestock has increased considerably in the light of frequent droughts affecting the region. For maximum utilization, mesquite pods are usually collected as they fall from trees and are then dried in the sun or in driers to reduce their moisture content from about 18–7% to facilitate grinding prior to feeding (Riveros, 1992). Several researchers have shown that heat treatment alters the site of nutrient digestion of feedstuffs in ruminants by reducing ruminal degradability thereby increasing the amount of nutrients available for intestinal digestion (Moshtaghi Nia and Ingalls, 1992; McKinnon et al., 1995). However, excessive heat treatment can reduce intestinal digestibility of ruminally undegraded nutrients, particularly protein (McKinnon et al., 1995; Moshtaghi Nia and Ingalls, 1992). Data on ruminal and whole tract nutrient digestibilities of mesquite pods are not available and effects of drying on nutrient utilization of mesquite pods by ruminants have not been determined. This experiment was designed to determine ruminal and intestinal nutrient digestibilities of unheated and heated mesquite pods. 2. Materials and methods 2.1. Heat treatment and chemical analysis Mesquite pods were dried at a local farm in the Sertanea area in Pernambuco state (Brazil) following procedures used by local farmers. The drying device was a locally made oven with wood generated heat and a capacity of 2 t per run. Mesquite pods were dried for 2 h at 80 ◦ C. The approximate depth of the mesquite pods in the oven was 30 cm and they were agitated twice during the 2 h drying period using metal shovels. Heat input was similar to that used by local farmers as it was found to sufficiently reduce the moisture content without causing evident heat damage to the pods. A thermometer monitored the temperature of the drying oven. Following drying, the mesquite pods were allowed to cool for 2 h and were ground through a 3 mm screen using a hammer mill. Three separate loads of the same mesquite pods were dried (n = 3). Sub-samples of mesquite pods before and after drying were collected, ground thought a 1 mm screen and analyzed for DM (method no. 930.15), ash (method no. 924.05), ether extract (method no. 920.39), crude protein (CP, method no. 984.13), acid detergent fiber (ADF, method no. 973.18), and acid detergent lignin (ADL, method no. 973.18) using the standard procedures of the Association of Official Analytical Chemists (AOAC, 1990). Neutral detergent fiber (NDF) was determined according to Van Soest et al. (1991) using heat-stable ␣ amylase, without the use of sodium sulfite and was
A.M. Batista et al. / Animal Feed Science and Technology 100 (2002) 107–112
109
not corrected for residual ash. Soluble CP, non-protein N, neutral detergent insoluble CP, and acid detergent insoluble CP were determined using procedures of Licitra et al. (1996). 2.2. In situ ruminal nutrient degradability Two steers (average body weight (BW) 650 ± 13.5 kg) fitted with flexible ruminal and proximal duodenal cannulas were utilized for this experiment. Animals were fed a 50:50 barley silage:concentrate diet (DM basis) at 1.5% of BW, in two equal portions at 08:00 and 16:00 h and had free access to water and cobalt-iodized salt. The concentrate mixture contained 137 g kg−1 CP, 227 g kg−1 NDF and 85 g kg−1 ADF (DM basis). Equal portions of the three samples of unheated and heated mesquite pods were composited and ground through a 2 mm screen to obtain a single sample of each treatment. Quadruplicate samples of each treatment were weighed into nylon bags (25 cm × 33 cm). Duplicate bags were incubated in the ventral sac of the rumen of the two steers for 0, 6, 12, 24, 48 and 72 h. Following removal from the rumen, bags were washed in tap water (20 ◦ C) and handled as described by McKinnon et al. (1991). Zero hour disappearance was estimated by washing duplicate bags containing samples of the two mesquite pod treatments. Residues from the nylon bags at each incubation time were analyzed for DM and CP as described previously. Ruminal disappearance data were used to estimate DM and CP degradation parameters using the equation of Ørskov and McDonald (1979): p = a + b(1 − e−ct ) where p is the ruminal disappearance at time t, a the soluble fraction (g kg−1 ), b the slowly degradable fraction (g kg−1 ), and c is the rate at which the b fraction is degraded (% h−1 ). Ruminal effective degradability (ED) of DM and CP were estimated for rumen mean retention time (MRT) of 12 h using the equation of Ørskov and McDonald: ED =
a + bc c+k
where k is the estimated rumen flow rate calculated as 1/MRT (8.3% h−1 ). 2.3. Intestinal nutrient disappearance Intestinal nutrient disappearances were determined using the mobile nylon bag technique (De Boer et al., 1987). Quadruplicate samples of both as collected and dried mesquite pods were incubated in the rumens of the two steers for 12 h, following the same procedure used in the ruminal degradability study. After removal form the rumen, bags were washed in tap water (20 ◦ C) until the water was clear, and then dried in a 55 ◦ C forced-air oven for 48 h. Residues remaining after ruminal incubation were composited by treatment. Samples (0.5 g) of ruminally undegraded residues were weighed into 10 small nylon bags (25 mm × 40 mm; 50 m pore size) per sample type and inserted through the duodenal cannulas of the two steers at the rate of one bag per hour. Bags recovered from the feces were handled and washed similarly to bags removed from the rumen. Residues from ruminal and intestinal incubations were analyzed for DM, CP, and NDF as described previously.
110
A.M. Batista et al. / Animal Feed Science and Technology 100 (2002) 107–112
2.4. Statistical analysis Chemical composition data were analyzed as a completely randomized design (two treatments and three replicates) using the General Linear Model of SAS (1989). Data of in situ ruminal and intestinal digestibilities were analyzed as a randomized complete block design, with steers as blocks. Where appropriate, means were separated using the Student–Newman–Keul’s test (Steel and Torrie, 1980). 3. Results and discussion 3.1. Chemical composition of mesquite pods Mesquite pod CP was comparable with other values (Table 1: Ibrahim and Gaili, 1985; Meyer et al., 1986). Protein fractionation showed that 635 g kg−1 of CP in mesquite pods was soluble while 157 and 96 g kg−1 was associated with NDF and ADF, respectively. Non-structural carbohydrates constituted 50% of DM in the as collected mesquite pods. It is likely that sugars are the main components of non-structural carbohydrates in mesquite pods as Meyer et al. (1986) indicated that the pericarp of the mesquite pod is rich in sugars (200–370 g kg−1 of DM) particularly sucrose. Drying decreased (P < 0.05) the soluble CP fraction. Several researchers have reported that moderate heat treatment reduced soluble CP (Moshtaghi Nia and Ingalls, 1992; Mustafa et al., 1998). 3.2. In situ ruminal degradability Mesquite pods had a relatively high in situ soluble, and low in situ degradable, DM fraction (Table 2). Drying increased (P < 0.05) the in situ slowly degradable DM fraction Table 1 Chemical composition of as collected and dried mesquite podsa (dry matter basis)
Dry matter Ash (g kg−1 ) Ether extract (g kg−1 ) Total carbohydrates (g kg−1 )c Neutral detergent fibre (g kg−1 ) Acid detergent fibre (g kg−1 ) Acid detergent lignin (g kg−1 ) Non-structural carbohydrates (g kg−1 )c Crude protein (g kg−1 of CP) Soluble protein (g kg−1 of CP) Non-protein nitrogen (g kg−1 of CP) Neutral detergent insoluble protein (g kg−1 of CP) Acid detergent insoluble protein (g kg−1 of CP) a
As collectedb
Driedb
S.E.M.
844 d 36 70 770 290 172 21 500 127 635 e 443 151 96
936 e 36 62 798 295 173 22 524 114 572 d 492 160 91
8.5 0.8 0.6 13.4 10.0 5.0 0.6 12.5 6.6 11.0 20.2 5.6 3.8
Number of samples analyzed for each treatment was three and all samples were analyzed in duplicate. Values marked with different letters (d, e) show significant differences between as collected and dried mesquite pods. c Calculated according to the equations of Sniffen et al. (1992). b
A.M. Batista et al. / Animal Feed Science and Technology 100 (2002) 107–112
111
Table 2 Ruminal, intestinal and total tract dry matter (DM) and crude protein (CP) utilization of as collected and dried mesquite pods As collecteda
Drieda
S.E.M.
DM ruminal kinetic parameters Soluble (% of DM) Slowly degraded (% of DM) Degradation rate (% h−1 ) Effective degradability (% of DM)
54.5 16.5 b 9.9 63.0
49.0 24.1 c 11.0 62.7
1.71 1.33 0.02 1.63
DM digestibility Ruminald (% of DM) Intestinal (% of DM) Whole tract (% of DM)
64.7 2.0 66.7
66.1 2.7 68.9
0.43 0.43 0.65
CP ruminal kinetic parameters Soluble (% of CP) Slowly degraded (% of CP) Degradation rate (% h−1 ) Effective degradability (% of DM)
47.6 c 38.9 b 4.9 b 62.0
32.3 b 51.8 c 6.8 c 61.3
1.62 2.11 0.01 0.92
CP digestibility Ruminald (% of CP) Intestinal (% of CP) Whole tract (% of CP)
65.5 10.8 76.4
68.1 12.2 80.2
1.70 1.58 1.68
7.8 1.0 8.8
8.3 1.3 9.7
0.61 0.40 0.58
NDF digestibility Ruminald (% of NDF) Intestinal (% of NDF) Whole tract (% of NDF)
S.E.M. = pooled standard error of the mean. a Values marked with different letters (b, c) show significant difference between unheated and heated mesquite pods (P < 0.05). d Determined following 12 h of ruminal incubation.
of mesquite pods without affecting other DM kinetic parameters or the effective ruminal DM degradability. This high ruminal DM degradability of mesquite pods is probably, at least partly, due to their high soluble sugar content (Meyer et al., 1986). Relative to the as collected pods, dried mesquite pods had a lower (P < 0.05) in situ soluble and a higher (P < 0.05) in situ slowly degradable CP fraction (Table 2). Drying increased (P < 0.05) the rate of degradation of the slowly degradable CP fraction, but the effective ruminal CP degradability was not affected. These ruminal DM and CP degradability values suggest that mesquite pods are highly degraded in the rumen. 3.3. Intestinal and total tract digestibilities Drying had no effect on ruminally undegraded DM, CP or NDF content of mesquite pods following 12 h of ruminal incubation (Table 2). The low ruminal degradability of mesquite cell wall was evident by the low NDF disappearance, <10%, after 12 h of ruminal
112
A.M. Batista et al. / Animal Feed Science and Technology 100 (2002) 107–112
incubation. Post-ruminal digestibilities of DM, CP and NDF for mesquite pods were also very low, and not affected by drying, showing that the rumen is the main digestion site of DM and CP in mesquite pods. Whole tract digestibilities of DM, CP and NDF were similar for as collected and dried mesquite pods. Comparative data on in vitro or in vivo digestibility of mesquite pods are not available.
4. Conclusions Mesquite pods have a high effective ruminal degradability with a relatively low intestinal digestibility of ruminally undegraded DM, CP and NDF. Drying mesquite pods at 80 ◦ C for 2 h had no detrimental effects on ruminal or whole tract nutrient utilization, but appears to have slowed release of N in the rumen, which may be beneficial under some feeding situations. References Association of Official Analytical Chemists 1990. Official Methods of Analysis, 15th Edition. AOAC, Arlington, VI, USA. De Boer, G., Murphy, J.J., Kennelly, J.J., 1987. A modifies method for determination of in situ rumen degradation of feedstuffs. Can. J. Anim. Sci. 67, 93–102. Ibrahim, A., Gaili, E.S., 1985. Performance and carcass traits of goats fed on diets containing different proportions of mesquite (Prosopis chilensis (Molina) Stuntz). Trop. Agric. 62, 97–99. Licitra, G., Mernandez, T.M., Van Soest, J.P., 1996. Standardization of procedures for nitrogen fractionation of ruminant feeds. Anim. Feed Sci. Technol. 57, 347–562. McKinnon, J.J., Olubobokun, J.A., Christensen, D.A., Cohen, R.D.H., 1991. The influence of heat and chemical treatment on ruminal disappearance of canola meal. Can. J. Anim. Sci. 71, 773–780. McKinnon, J.J., Olubobokun, J.A., Mustafa, A.F., Cohen, R.D.H., Christensen, D.A., 1995. Influence of dry heat treatment of canola meal on site and extent of nutrient disappearance of canola meal. Anim. Feed Sci. Technol. 56, 243–252. Meyer, D., Becker, R., Gumbmann, M.R., Neukom, H., Saunders, R.M., 1986. Processing, composition, nutritional evaluation, and utilization of mesquite (Prosopis spp.) pods as raw material for the food industry. J. Agric. Food. Chem. 34, 914–919. Moshtaghi Nia, S.A., Ingalls, J.R., 1992. Effect of heating on canola meal protein degradation in the rumen and digestion in the lower gastrointestinal tract of steers. Can. J. Anim. Sci. 72, 83–88. Mustafa, A.F., Christensen, D.A., McKinnon, J.J., 1998. Effect of moist heat treatment on crude protein composition and degradability of field peas. Can. J. Anim. Sci. 78, 453–456. Ørskov, E.R., McDonald, I., 1979. The estimation of protein degradability in the rumen from incubation measurements weighed according to rate of passage. J. Agric. Sci. 92, 499–503. Riveros, F., 1992. The genus Prosopis and its potential to improve livestock production in arid and semi arid regions. In: Speedy, A., Pugliese, P. (Eds.), Legume Trees and Other Fodder Trees as Protein Sources for Livestock. FAO Animal Production and Health Paper 102, pp. 257–276. SAS® User’s Guide: Statistics, Version 6. 1989. SAS Institute, Inc., Cary, NC, USA. Steel, R.G., Torrie, J.H., 1980. Principles and Procedures of Statistics. McGraw-Hill, New York, USA. Tabosa, I.M., Souza, J.C., Graca, D.L., Barbosa, J.M., Almeida, R.N., Riet-Correa, F., 2000. Neural vacuolation of the trigeminal nuclei in goats caused by ingestion of Prosopis juliflora (mesquite beans). Vet. Hum. Toxicol. 42, 155–158. Talpada, P.M., Shukla, P.C., 1988. Influence of feeding Prosopis juliflora pods on digestibility and balances in lactating cows. Indian J. Anim. Sci. 58, 727–730. Van Soest, P.J., Robertson, P.J., Lewis, B.A., 1991. Methods for dietary fiber, neutral detergent fiber, and nonstarch polysaccharides in relation to animal nutrition. J. Dairy Sci. 74, 3583–3597.
Short communication
In situ ruminal and intestinal nutrient digestibilities of mesquite (Prosopis juliflora) pods A.M. Batista a,b , A.F. Mustafa c,∗ , J.J. McKinnon d , S. Kermasha e a
Bolsista da Coordenacao de Aperfeicoamento de Pessoal de Nivel Superior, Brasilia, DF, Brazil b Departamento de Zootecnia, Universidade Federal Rural de Pernambuco, Recife-PE, Brazil c Department of Animal Science, MacDonald Campus, McGill University, 21,111 Lakeshore Road, Ste-Anne de Bellevue, Que., Canada H9X 3V9 d Department of Animal and Poultry Science, University of Saskatchewan, Saskatoon, Sask., Canada e Department of Food Science, McGill University, Ste-Anne de Bellevue, Que., Canada H9X 3V9 Received 17 July 2001; received in revised form 8 April 2002; accepted 8 May 2002
Abstract Two steers fitted with ruminal and duodenal cannulas were used in a randomized complete block design to determine ruminal and intestinal digestibility of dry matter (DM), crude protein (CP) and neutral detergent fiber (NDF) from as collected and dried (80 ◦ C for 2 h) mesquite pods. On a DM basis, as collected mesquite pods contained 290 g kg−1 neutral detergent fibre, 172 g kg−1 acid detergent fibre, and 127 g kg−1 CP. Drying at 80 ◦ C for 2 h reduced (P < 0.05) the in situ soluble CP fraction and increased (P < 0.05) the slowly degradable CP fraction and its rate of degradation. However, ruminal degradability of both CP and DM of mesquite pods were not affected by drying. Post-ruminally digestibility of ruminal undegraded CP and NDF were low and unaffected by drying. Total tract digestibility of DM, CP and NDF were similar for as collected and dried mesquite pods, averaging 68, 78 and 9%, respectively. It was concluded that the rumen is the main site of digestion of mesquite pods and that drying at 80 ◦ C for 2 h had no adverse effects on their intestinal or total tract digestibilities. © 2002 Elsevier Science B.V. All rights reserved. Keywords: Mesquite pods; Ruminal degradability; Intestinal and total tract digestibility
1. Introduction Mesquite (Prosopis juliflora) is a leguminous tree that is native to arid and semi-arid regions of the world. The tree produces flattened, multi-seeded and curved pods with hardened pericarp. Mesquite pods are a significant feed source for livestock in many areas of the ∗ Corresponding author. Tel.: +1-514-398-7506; fax: +1-514-398-7964. E-mail address: [email protected] (A.F. Mustafa).
0377-8401/02/$ – see front matter © 2002 Elsevier Science B.V. All rights reserved. PII: S 0 3 7 7 - 8 4 0 1 ( 0 2 ) 0 0 1 3 6 - 0
108
A.M. Batista et al. / Animal Feed Science and Technology 100 (2002) 107–112
world (Riveros, 1992). Pod production per tree can vary from a few kg to over 400 kg and is highly dependent on moisture availability to the plant (Riveros, 1992). Despite the fact that mesquite pods are widely used as animal feed in many developing countries, data on their feeding value for ruminants are limited. Ibrahim and Gaili (1985) found that mesquite pods can be used as a maintenance feed for male goats when included at 60–70% of the diet DM. However, male goats fed 85 or 100% mesquite pod based diets experienced weight loss. Talpada and Shukla (1988) showed that mesquite pods can be incorporated into diets of Indian Kankrej cows at levels up to 15% of the concentrate (5% of DMI) with no adverse effects on milk production or on total tract nutrient digestibilities. In the northeast region of Brazil, mesquite trees cover 150,000 ha (Tabosa et al., 2000) and the importance of mesquite pods as a nutrient source for livestock has increased considerably in the light of frequent droughts affecting the region. For maximum utilization, mesquite pods are usually collected as they fall from trees and are then dried in the sun or in driers to reduce their moisture content from about 18–7% to facilitate grinding prior to feeding (Riveros, 1992). Several researchers have shown that heat treatment alters the site of nutrient digestion of feedstuffs in ruminants by reducing ruminal degradability thereby increasing the amount of nutrients available for intestinal digestion (Moshtaghi Nia and Ingalls, 1992; McKinnon et al., 1995). However, excessive heat treatment can reduce intestinal digestibility of ruminally undegraded nutrients, particularly protein (McKinnon et al., 1995; Moshtaghi Nia and Ingalls, 1992). Data on ruminal and whole tract nutrient digestibilities of mesquite pods are not available and effects of drying on nutrient utilization of mesquite pods by ruminants have not been determined. This experiment was designed to determine ruminal and intestinal nutrient digestibilities of unheated and heated mesquite pods. 2. Materials and methods 2.1. Heat treatment and chemical analysis Mesquite pods were dried at a local farm in the Sertanea area in Pernambuco state (Brazil) following procedures used by local farmers. The drying device was a locally made oven with wood generated heat and a capacity of 2 t per run. Mesquite pods were dried for 2 h at 80 ◦ C. The approximate depth of the mesquite pods in the oven was 30 cm and they were agitated twice during the 2 h drying period using metal shovels. Heat input was similar to that used by local farmers as it was found to sufficiently reduce the moisture content without causing evident heat damage to the pods. A thermometer monitored the temperature of the drying oven. Following drying, the mesquite pods were allowed to cool for 2 h and were ground through a 3 mm screen using a hammer mill. Three separate loads of the same mesquite pods were dried (n = 3). Sub-samples of mesquite pods before and after drying were collected, ground thought a 1 mm screen and analyzed for DM (method no. 930.15), ash (method no. 924.05), ether extract (method no. 920.39), crude protein (CP, method no. 984.13), acid detergent fiber (ADF, method no. 973.18), and acid detergent lignin (ADL, method no. 973.18) using the standard procedures of the Association of Official Analytical Chemists (AOAC, 1990). Neutral detergent fiber (NDF) was determined according to Van Soest et al. (1991) using heat-stable ␣ amylase, without the use of sodium sulfite and was
A.M. Batista et al. / Animal Feed Science and Technology 100 (2002) 107–112
109
not corrected for residual ash. Soluble CP, non-protein N, neutral detergent insoluble CP, and acid detergent insoluble CP were determined using procedures of Licitra et al. (1996). 2.2. In situ ruminal nutrient degradability Two steers (average body weight (BW) 650 ± 13.5 kg) fitted with flexible ruminal and proximal duodenal cannulas were utilized for this experiment. Animals were fed a 50:50 barley silage:concentrate diet (DM basis) at 1.5% of BW, in two equal portions at 08:00 and 16:00 h and had free access to water and cobalt-iodized salt. The concentrate mixture contained 137 g kg−1 CP, 227 g kg−1 NDF and 85 g kg−1 ADF (DM basis). Equal portions of the three samples of unheated and heated mesquite pods were composited and ground through a 2 mm screen to obtain a single sample of each treatment. Quadruplicate samples of each treatment were weighed into nylon bags (25 cm × 33 cm). Duplicate bags were incubated in the ventral sac of the rumen of the two steers for 0, 6, 12, 24, 48 and 72 h. Following removal from the rumen, bags were washed in tap water (20 ◦ C) and handled as described by McKinnon et al. (1991). Zero hour disappearance was estimated by washing duplicate bags containing samples of the two mesquite pod treatments. Residues from the nylon bags at each incubation time were analyzed for DM and CP as described previously. Ruminal disappearance data were used to estimate DM and CP degradation parameters using the equation of Ørskov and McDonald (1979): p = a + b(1 − e−ct ) where p is the ruminal disappearance at time t, a the soluble fraction (g kg−1 ), b the slowly degradable fraction (g kg−1 ), and c is the rate at which the b fraction is degraded (% h−1 ). Ruminal effective degradability (ED) of DM and CP were estimated for rumen mean retention time (MRT) of 12 h using the equation of Ørskov and McDonald: ED =
a + bc c+k
where k is the estimated rumen flow rate calculated as 1/MRT (8.3% h−1 ). 2.3. Intestinal nutrient disappearance Intestinal nutrient disappearances were determined using the mobile nylon bag technique (De Boer et al., 1987). Quadruplicate samples of both as collected and dried mesquite pods were incubated in the rumens of the two steers for 12 h, following the same procedure used in the ruminal degradability study. After removal form the rumen, bags were washed in tap water (20 ◦ C) until the water was clear, and then dried in a 55 ◦ C forced-air oven for 48 h. Residues remaining after ruminal incubation were composited by treatment. Samples (0.5 g) of ruminally undegraded residues were weighed into 10 small nylon bags (25 mm × 40 mm; 50 m pore size) per sample type and inserted through the duodenal cannulas of the two steers at the rate of one bag per hour. Bags recovered from the feces were handled and washed similarly to bags removed from the rumen. Residues from ruminal and intestinal incubations were analyzed for DM, CP, and NDF as described previously.
110
A.M. Batista et al. / Animal Feed Science and Technology 100 (2002) 107–112
2.4. Statistical analysis Chemical composition data were analyzed as a completely randomized design (two treatments and three replicates) using the General Linear Model of SAS (1989). Data of in situ ruminal and intestinal digestibilities were analyzed as a randomized complete block design, with steers as blocks. Where appropriate, means were separated using the Student–Newman–Keul’s test (Steel and Torrie, 1980). 3. Results and discussion 3.1. Chemical composition of mesquite pods Mesquite pod CP was comparable with other values (Table 1: Ibrahim and Gaili, 1985; Meyer et al., 1986). Protein fractionation showed that 635 g kg−1 of CP in mesquite pods was soluble while 157 and 96 g kg−1 was associated with NDF and ADF, respectively. Non-structural carbohydrates constituted 50% of DM in the as collected mesquite pods. It is likely that sugars are the main components of non-structural carbohydrates in mesquite pods as Meyer et al. (1986) indicated that the pericarp of the mesquite pod is rich in sugars (200–370 g kg−1 of DM) particularly sucrose. Drying decreased (P < 0.05) the soluble CP fraction. Several researchers have reported that moderate heat treatment reduced soluble CP (Moshtaghi Nia and Ingalls, 1992; Mustafa et al., 1998). 3.2. In situ ruminal degradability Mesquite pods had a relatively high in situ soluble, and low in situ degradable, DM fraction (Table 2). Drying increased (P < 0.05) the in situ slowly degradable DM fraction Table 1 Chemical composition of as collected and dried mesquite podsa (dry matter basis)
Dry matter Ash (g kg−1 ) Ether extract (g kg−1 ) Total carbohydrates (g kg−1 )c Neutral detergent fibre (g kg−1 ) Acid detergent fibre (g kg−1 ) Acid detergent lignin (g kg−1 ) Non-structural carbohydrates (g kg−1 )c Crude protein (g kg−1 of CP) Soluble protein (g kg−1 of CP) Non-protein nitrogen (g kg−1 of CP) Neutral detergent insoluble protein (g kg−1 of CP) Acid detergent insoluble protein (g kg−1 of CP) a
As collectedb
Driedb
S.E.M.
844 d 36 70 770 290 172 21 500 127 635 e 443 151 96
936 e 36 62 798 295 173 22 524 114 572 d 492 160 91
8.5 0.8 0.6 13.4 10.0 5.0 0.6 12.5 6.6 11.0 20.2 5.6 3.8
Number of samples analyzed for each treatment was three and all samples were analyzed in duplicate. Values marked with different letters (d, e) show significant differences between as collected and dried mesquite pods. c Calculated according to the equations of Sniffen et al. (1992). b
A.M. Batista et al. / Animal Feed Science and Technology 100 (2002) 107–112
111
Table 2 Ruminal, intestinal and total tract dry matter (DM) and crude protein (CP) utilization of as collected and dried mesquite pods As collecteda
Drieda
S.E.M.
DM ruminal kinetic parameters Soluble (% of DM) Slowly degraded (% of DM) Degradation rate (% h−1 ) Effective degradability (% of DM)
54.5 16.5 b 9.9 63.0
49.0 24.1 c 11.0 62.7
1.71 1.33 0.02 1.63
DM digestibility Ruminald (% of DM) Intestinal (% of DM) Whole tract (% of DM)
64.7 2.0 66.7
66.1 2.7 68.9
0.43 0.43 0.65
CP ruminal kinetic parameters Soluble (% of CP) Slowly degraded (% of CP) Degradation rate (% h−1 ) Effective degradability (% of DM)
47.6 c 38.9 b 4.9 b 62.0
32.3 b 51.8 c 6.8 c 61.3
1.62 2.11 0.01 0.92
CP digestibility Ruminald (% of CP) Intestinal (% of CP) Whole tract (% of CP)
65.5 10.8 76.4
68.1 12.2 80.2
1.70 1.58 1.68
7.8 1.0 8.8
8.3 1.3 9.7
0.61 0.40 0.58
NDF digestibility Ruminald (% of NDF) Intestinal (% of NDF) Whole tract (% of NDF)
S.E.M. = pooled standard error of the mean. a Values marked with different letters (b, c) show significant difference between unheated and heated mesquite pods (P < 0.05). d Determined following 12 h of ruminal incubation.
of mesquite pods without affecting other DM kinetic parameters or the effective ruminal DM degradability. This high ruminal DM degradability of mesquite pods is probably, at least partly, due to their high soluble sugar content (Meyer et al., 1986). Relative to the as collected pods, dried mesquite pods had a lower (P < 0.05) in situ soluble and a higher (P < 0.05) in situ slowly degradable CP fraction (Table 2). Drying increased (P < 0.05) the rate of degradation of the slowly degradable CP fraction, but the effective ruminal CP degradability was not affected. These ruminal DM and CP degradability values suggest that mesquite pods are highly degraded in the rumen. 3.3. Intestinal and total tract digestibilities Drying had no effect on ruminally undegraded DM, CP or NDF content of mesquite pods following 12 h of ruminal incubation (Table 2). The low ruminal degradability of mesquite cell wall was evident by the low NDF disappearance, <10%, after 12 h of ruminal
112
A.M. Batista et al. / Animal Feed Science and Technology 100 (2002) 107–112
incubation. Post-ruminal digestibilities of DM, CP and NDF for mesquite pods were also very low, and not affected by drying, showing that the rumen is the main digestion site of DM and CP in mesquite pods. Whole tract digestibilities of DM, CP and NDF were similar for as collected and dried mesquite pods. Comparative data on in vitro or in vivo digestibility of mesquite pods are not available.
4. Conclusions Mesquite pods have a high effective ruminal degradability with a relatively low intestinal digestibility of ruminally undegraded DM, CP and NDF. Drying mesquite pods at 80 ◦ C for 2 h had no detrimental effects on ruminal or whole tract nutrient utilization, but appears to have slowed release of N in the rumen, which may be beneficial under some feeding situations. References Association of Official Analytical Chemists 1990. Official Methods of Analysis, 15th Edition. AOAC, Arlington, VI, USA. De Boer, G., Murphy, J.J., Kennelly, J.J., 1987. A modifies method for determination of in situ rumen degradation of feedstuffs. Can. J. Anim. Sci. 67, 93–102. Ibrahim, A., Gaili, E.S., 1985. Performance and carcass traits of goats fed on diets containing different proportions of mesquite (Prosopis chilensis (Molina) Stuntz). Trop. Agric. 62, 97–99. Licitra, G., Mernandez, T.M., Van Soest, J.P., 1996. Standardization of procedures for nitrogen fractionation of ruminant feeds. Anim. Feed Sci. Technol. 57, 347–562. McKinnon, J.J., Olubobokun, J.A., Christensen, D.A., Cohen, R.D.H., 1991. The influence of heat and chemical treatment on ruminal disappearance of canola meal. Can. J. Anim. Sci. 71, 773–780. McKinnon, J.J., Olubobokun, J.A., Mustafa, A.F., Cohen, R.D.H., Christensen, D.A., 1995. Influence of dry heat treatment of canola meal on site and extent of nutrient disappearance of canola meal. Anim. Feed Sci. Technol. 56, 243–252. Meyer, D., Becker, R., Gumbmann, M.R., Neukom, H., Saunders, R.M., 1986. Processing, composition, nutritional evaluation, and utilization of mesquite (Prosopis spp.) pods as raw material for the food industry. J. Agric. Food. Chem. 34, 914–919. Moshtaghi Nia, S.A., Ingalls, J.R., 1992. Effect of heating on canola meal protein degradation in the rumen and digestion in the lower gastrointestinal tract of steers. Can. J. Anim. Sci. 72, 83–88. Mustafa, A.F., Christensen, D.A., McKinnon, J.J., 1998. Effect of moist heat treatment on crude protein composition and degradability of field peas. Can. J. Anim. Sci. 78, 453–456. Ørskov, E.R., McDonald, I., 1979. The estimation of protein degradability in the rumen from incubation measurements weighed according to rate of passage. J. Agric. Sci. 92, 499–503. Riveros, F., 1992. The genus Prosopis and its potential to improve livestock production in arid and semi arid regions. In: Speedy, A., Pugliese, P. (Eds.), Legume Trees and Other Fodder Trees as Protein Sources for Livestock. FAO Animal Production and Health Paper 102, pp. 257–276. SAS® User’s Guide: Statistics, Version 6. 1989. SAS Institute, Inc., Cary, NC, USA. Steel, R.G., Torrie, J.H., 1980. Principles and Procedures of Statistics. McGraw-Hill, New York, USA. Tabosa, I.M., Souza, J.C., Graca, D.L., Barbosa, J.M., Almeida, R.N., Riet-Correa, F., 2000. Neural vacuolation of the trigeminal nuclei in goats caused by ingestion of Prosopis juliflora (mesquite beans). Vet. Hum. Toxicol. 42, 155–158. Talpada, P.M., Shukla, P.C., 1988. Influence of feeding Prosopis juliflora pods on digestibility and balances in lactating cows. Indian J. Anim. Sci. 58, 727–730. Van Soest, P.J., Robertson, P.J., Lewis, B.A., 1991. Methods for dietary fiber, neutral detergent fiber, and nonstarch polysaccharides in relation to animal nutrition. J. Dairy Sci. 74, 3583–3597.