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Nutritive value of forage shrubs: Bituminaria bituminosa, Rumex lunaria, Acacia salicina, Cassia sturtii and Adenocorpus foliosus
Small Ruminant Research 52 (2004) 13–18
Nutritive value of forage shrubs: Bituminaria bituminosa, Rumex lunaria, Acacia salicina, Cassia sturtii and Adenocorpus foliosus M.R. Ventura, J.I.R. Castañón∗ , M.C. Pieltain, M.P. Flores Department of Animal Science, University of Las Palmas de Gran Canaria, 35001 Las Palmas de Gran Canaria, Spain Received 27 February 2002; received in revised form 5 February 2003; accepted 4 March 2003
Abstract The nutritive value of three forage shrubs endemic from Canary Islands (Bituminaria bituminosa, Rumex lunaria, Adenocorpus foliosus) and two introduced shrubs (Acacia salicina, Cassia sturtii) was studied along the year. Mean organic matter, neutral detergent fibre and protein content (g kg−1 dry matter (DM)) of four cuts along the year was, respectively, 910, 424 and 184 for B. bituminosa, 865, 329 and 149 for R. lunaria, 955, 452 and 159 for A. foliosus, 879, 412 and 123 for A. salicina, 937, 390 and 102 for C. sturtii. Mean calcium content (kg−1 DM) was the highest for A. salicina (25.1 g), the lowest for A. foliosus (3.2 g), and moderate for the others (range 10.4–14.3 g). Mean phosphorus content of shrubs ranged 1.5–2.8 g kg−1 DM. Mean tannin content (g catequins kg−1 DM) was the highest for C. sturtii and R. lunaria (0.63 and 0.54 g, respectively) and moderate for A. salicina (0.24 g), while B. bituminosa and A. foliosus had only traces of tannins. Mean ruminal organic matter degradability, protein degradability and in vitro organic matter digestibility were, respectively, 57.5, 72.2 and 64.6% for B. bituminosa, 50.5, 57.0 and 56.2% for R. lunaria, 49.7, 55.4 and 59.6% for A. foliosus, 33.5, 30.4 and 37.4% for A. salicina, 53.5, 56.4 and 38.8% for C. sturtii. From these results, the net energy content of B. bituminosa, R. lunaria, A. foliosus, A. salicina and C. sturtii was estimated to be, respectively, 5.6, 4.7, 5.4, 3.2 and 3.3 MJ kg−1 DM, with significant differences among species and seasons. © 2003 Elsevier B.V. All rights reserved. Keywords: Bituminaria; Acacia; Rumex; Cassia; Adenocarpus; Legume shrubs; Nutritive value
1. Introduction Forage shrubs are useful forages for arid areas because of their adaptation and productivity in dry climates and poor soils. B. bituminosa, A. foliosus and R. lunaria are endemic forages shrubs from Canary Islands, and A. salicina and C. sturtii are legume browse trees used in arid zones of Africa and other areas (Houerou, 1980). Although these species have been widely used in ruminant feed, scarce research has been ∗ Corresponding author. Tel.: +34-928-451133; fax: +34-928-451142. E-mail address: [email protected] (J.I.R. Castañ´on).
carried out to determine their nutritive value (Mendez and Fernandez, 1990; Ventura, 1997). In this research, the nutritive value of these legume shrubs along the year was studied by chemical composition analyses, tannin content, ruminal degradability and in vitro digestibility trials. 2. Materials and methods Hand-samples of the different species were taken in different seasons of the year (spring—April, summer—August, autumn—November and winter— February) from shrubs in an experimental plot where
0921-4488/$ – see front matter © 2003 Elsevier B.V. All rights reserved. doi:10.1016/S0921-4488(03)00225-6
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M.R. Ventura et al. / Small Ruminant Research 52 (2004) 13–18
all the species were grown under the same climatic conditions: 300–400 mm mean annual rainfall, 19.3 ◦ C mean annual temperature, 6 ◦ C minimum winter temperature and 220 mm highest summer evapotranspiration. Each sample consisted of leaves and thin stems (less than 3 mm of diameter) of the shrubs. The samples were air-dried to constant weight in a fan-assisted oven at 60 ◦ C for 2 days and then they were ground to pass through a 1 mm sieve. Dry matter (DM), ash, minerals and crude protein (CP) were analysed according to standard methods (AOAC, 1990). Detergent fibres and acid detergent lignin were analysed according to Van Soest et al. (1991). A mixture of samples from different seasons was analysed to determine the ether extract (EE) content according to AOAC (1990) and the condensed tannin content of each shrub by the modified vanillin method (Price et al.,
1978) using a Pye-Unicam SP6-550 spectrophotometer. Ruminal organic matter and crude protein degradability was determined using nylon bags with four fistulated adult Canarian male goats, fed at maintenance level with a mixture of shrubs ad libitum and 200 g whole maize grain (100 g twice daily) during the entire 15 days experimental period (3 days to assess each shrubs). Duplicate bags with 3 g sample were incubated for 0, 6, 18, 24, 48 and 72 h in the rumen of each goat according to Ganev et al. (1979). Effective degradability was determinated according to Orskov and McDonald (1979), using the GLM procedure (SAS, 1989) and assuming 0.04 h−1 as the theoretical passage rate (INRA, 1988). Dry and organic matter in vitro digestibilities of duplicate samples was determined using the two-stage technique (Tilley and Terry, 1963).
Table 1 Chemical composition (g kg−1 DM) of shrubs
B. bituminosa
R. lunaria
A. salicina
C. sturtii
A. foliosus
Time
DM
OM
Spring Summer Autumn Winter
311 266 270 247
Mean
274 ± 23
910 ± 13
184 ± 18
424 ± 36
296 ± 52
73 ± 18
Spring Summer Autumn Winter
373 332 181 144
874 826 875 885
122 108 183 181
328 232 374 381
290 165 280 275
78 82 83 81
Mean
258 ± 97
865 ± 23
149 ± 34
329 ± 60
252 ± 51
Spring Summer Autumn Winter
317 347 338 351
910 863 862 879
133 90 128 142
499 330 402 416
302 232 305 256
Mean
338 ± 13
879 ± 19
123 ± 20
412 ± 60
274 ± 31
102 ± 9
Spring Summer Autumn Winter
399 615 446 323
947 926 934 941
75 87 117 130
349 389 393 428
206 274 297 237
69 91 86 104
Mean
446 ± 97
937 ± 8
102 ± 22
390 ± 28
254 ± 35
88 ± 13
Spring Summer Winter
494 a,b 544 a 438 b
952 955 957
160 a,b 136 b 182 a
453 a,b 485 a 419 b
319 a 327 a 256 b
98 80 83
Mean
492 ± 43
955 ± 2
159 ± 19
452 ± 27
300 ± 32
87 ± 8
a a,b a,b b
a a b b
b a a a
b,c a b c
915 911 890 925
CP a,b a,b b a
a b a a
a b b a,b
198 159 204 173
a b a a,b
b b a a
a b a a
b b a a
NDF
ADF
ADL
380 417 481 416
256 323 368 238
52 59 82 98
b a,b a a,b
a,b b a a
a c b b
b a,b a,b a
b a a b
a b a a
a b a b
b a a b
Means with different letters (a, b and c) in the same column of each shrub differ significantly (P < 0.05).
b b a,b a
81 ± 2 88 103 113 102
EE
29 ± 5.4
28 ± 4.3
b a,b a a,b 23 ± 6.2
c a,b b,c a 21 ± 3.4
20 ± 2.3
M.R. Ventura et al. / Small Ruminant Research 52 (2004) 13–18
Based on digestible organic matter (DOM) content of forages, metabolizable energy (ME, MJ kg−1 DM) content of the shrubs was estimated as 0.015 × DOM (MAFF, 1984). The net energy for lactation (NE) content was calculated using the ratio NE/ME = 0.60 (Sauvant and Morand-Fehr, 1991), where ME is the metabolizable energy content of the feed. The effects of season on the chemical composition and the nutritive value of each shrubs were compared by LSD tests (SAS, 1989), and a level of P < 0.05 was chosen as the minimum for statistical significance.
3. Results Chemical composition of browse samples is shown in Table 1. Mean nutrient contents of forages were 35.6% DM (range 14.4–61.5%), 909 g OM kg−1 DM (range 826–957), and 401 g NDF kg−1 DM (range 232–499), with significant differences among species
15
and seasons. Mean crude protein content of shrubs was 143 g kg−1 DM (range 75–204). Mineral and tannin contents of forages are shown in Table 2. Mean mineral contents of shrubs, per kg DM, were 13.3 g Ca (range 2.3–34.8) and 2.1 g P (range 1.2–3.3). The highest tannin content was found in R. lunaria and C. sturtii, while B. bituminosa and A. foliosus had only traces of tannins. Ruminal degradability of organic matter and crude protein are shown in Table 3. Mean organic matter degradability of forages was 48.9% (range 29.4–67.5%), and mean protein degradability was 54.3% (range 24.3–77.6%). Mean organic matter in vitro digestibility (IVOMD) of shrubs was 51.3% (range 24.9–68.2%). Estimated net energy content (Table 3) of forages ranged 2.1–6.0 MJ NE kg−1 DM, with significant differences among species and seasons, with the highest values for B. bituminosa and A. foliosus, and the lowest values for A. salicina and C. sturtii.
Table 2 Mineral (g kg−1 DM) and tannin contents (g catequins kg−1 DM) of shrubs
B. bituminosa
R. lunaria
A. salicina
C. sturtii
A. foliosus
Time
Ca
P
Spring Summer Autumn Winter
11.3 10.6 11.0 8.6
2.6 2.5 3.1 3.2
2.2 1.8 2.6 1.6
Mean
10.4 ± 1.0
2.8 ± 0.3
2.0 ± 0.4
Spring Summer Autumn Winter
13.3 17.6 11.6 14.7
1.8 1.9 2.8 3.3
Mean
14.3 ± 5.3
2.5 ± 0.6
8.2 ± 2.2
8.1 ± 5.1
31.7 ± 9.7
Summer Autumn Winter
34.8 a 17.7 b 22.7 a,b
1.6 1.3 1.5
1.0 a 1.6 a 1.3 b
4.5 3.0 3.7
19.2 15.8 15.0
Mean
25.1 ± 11
1.5 ± 0.1
1.3 ± 0.2
3.7 ± 0.6
16.6 ± 1.8
Summer Autumn Winter
11.8 b 15.8 a 12.5 b
1.2 b 2.0 a 1.9 a
1.3 1.3 1.1
4.5 a 3.5 a,b 2.8 b
18.0 a 13.8 b 15.8 a,b
Mean
13.4 ± 1.7
1.7 ± 0.4
1.2 ± 0.1
3.6 ± 0.7
15.9 ± 1.7
a,b a b a,b
Mg
b b a a
7.6 10.1 6.4 8.6
Na a,b a,b a b
b a b a,b
K
Tannins
2.5 2.4 2.7 3.0
26.6 32.2 29.3 33.3
2.6 ± 0.2
30.3 ± 2.6
12.8 6.5 7.0 6.2
a b b b
24.7 44.6 26.0 31.5
b a a,b a
b a b b
Spring Summer Winter
3.3 4.0 2.3
1.8 1.3 2.3
1.8 2.2 1.3
3.8 3.5 2.9
18.9 a 10.6 b 13.9 b
Mean
3.2 ± 0.7
1.8 ± 0.4
1.8 ± 0.4
3.4 ± 0.4
14.5 ± 4.8
Means with different letters (a, b and c) in the same column of each shrub differ significantly (P < 0.05).
0.02 ± 0.004
0.54 ± 0.02
0.24 ± 0.01
0.63 ± 0.01
0.01 ± 0.005
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M.R. Ventura et al. / Small Ruminant Research 52 (2004) 13–18
Table 3 Organic matter and protein ruminal degradability (OMD, CPD, %), in vitro dry matter and organic matter digestibility (IVDMD, IVOMD, %), digestible organic matter (DOM, g kg−1 DM) and estimated net energy content (NE, MJ kg−1 DM) of shrubs Time
OMD
CPD
B. bituminosa
Spring Summer Autumn Winter
56.2 47.7 58.7 67.5
70.5 66.5 74.2 77.6
Mean
57.5 ± 7.0
72.2 ± 4.2
67.9 ± 2.9
64.6 ± 33
588 ± 38
5.6 ± 0.3
R. lunaria
Spring Summer Autumn Winter
41.8 49.0 50.6 60.4
47.1 50.5 60.5 70.1
63 a,b 58.4 b 58.4 b 69.0 a
57.7 49.6 52.5 64.9
504 410 459 574
4.9 4.0 4.5 5.5
Mean
50.5 ± 6.6
57.0 ± 9.0
62.2 ± 4.4
56.2 ± 5.8
487 ± 61
4.7 ± 0.5
A. salicina
Spring Summer Autumn Winter
32.6 41.3 29.4 30.7
24.3 36.2 27.5 33.8
36.0 54.8 45.0 43.7
33.0 47.6 36.2 35.9
300 411 312 316
2.9 4.0 3.1 3.1
Mean
33.5 ± 4.6
30.4 ± 4.7
44.9 ± 6.8
37.4 ± 6.0
334 ± 44
3.2 ± 0.4
C. sturtii
Spring Summer Autumn Winter
53.8 49.6 54.1 56.4
44.9 52.5 62.1 66.2
28.9 40.0 52.3 49.6
24.9 35.2 48.9 46.4
236 326 457 437
2.1 3.0 4.2 4.0
Mean
53.5 ± 2.4
56.4 ± 8.3
42.7 ± 9.4
38.8 ± 9.6
364 ± 83
3.3 ± 0.6
A. foliosus
Spring Summer Winter
45.8 b 45.8 b 57.5 a
49.3 b 52.4 b 64.4 a
60.9 60.1 63.5
58.9 58.2 61.7
561 b 556 b 590 a
5.3 b 5.3 b 5.6 a
Mean
49.7 ± 5.5
55.4 ± 6.5
61.5 ± 1.7
59.6 ± 1.5
569 ± 15
5.4 ± 0.1
b c b a
c b b a
b a b b
a,b b a,b a
b,c c a,b a
c c b a
b a b a
c b,c a,b a
IVDMD
IVOMD
DOM
NE
68.2 68.9 63.7 70.6
65.1 65.9 59.2 68.2
595 600 527 631
5.7 5.7 5.1 6.0
a,b a,b b a
c a b b,c
c b a a
a a b a
a,b c b,c a
b a b b
b b a a
a a b a
a,b c b,c a
b a b b
c b a a
a a b a
a,b c b,c a
a a b b
c b a a
Means with different letters (a, b and c) in the same column of each shrub differ significantly (P < 0.05).
4. Discussion 4.1. Bituminaria bituminosa and Adenocarpus foliosus These two shrubs had the highest crude protein content of the studied forages (mean 16–18%), with the lowest content in the summer cuts. The fibre content of these forages also was the highest (more than 400 g NDF kg−1 DM), but it was a low lignificated fibre (less than 20% of NDF was ADL). Only traces of tannins were found in these species. The main differences between these two forages was the DM content and the low calcium content of A. foliosus. Organic matter and protein degradability of B. bituminosa (57.5 and 72.2%, respectively) was the highest of the studied species, while the degradability of
A. foliosus nutrients was moderate (49.7 and 55.4%, respectively). Organic matter in vitro digestibility and DOM content of these species (60–65% and more than 550 g DOM kg−1 DM, respectively) were also the highest. Therefore, the mean NE content of these shrubs was high (mean 5.5 MJ kg−1 DM), similar to that estimated by Mendez (1992), with the highest content in winter cuts. The results of this research suggest that 1 kg DM of these shrubs could cover the energy and protein requirements reported by INRA (1988) for maintenance of 50 kg-goats. 4.2. Rumex lunaria R. lunaria had the lowest DM content (25.8%) of the shrubs, particularly the autumn and winter cuts. The protein content of this forage was high (18%) in
M.R. Ventura et al. / Small Ruminant Research 52 (2004) 13–18
autumn and winter cuts, and moderate (11–12%) in the other seasons. Fibre content of R. lunaria was the lowest (329 g NDF kg−1 DM) of the studied shrubs, but with a relatively high lignification (25% of NDF was ADL). The content of some minerals (Mg, Na and K) was the highest of the analysed shrubs. Some authors (Rodr´ıguez et al., 1985) have reported that R. lunaria contains oxalates, which could reduce the digestibility of some minerals, particularly calcium. Organic matter and protein degradability of R. lunaria were 50.5 and 57.0%, respectively. Although R. lunaria had a relatively high tannin content (0.54 g catequins kg−1 DM), organic matter in vitro digestibility and DOM content (56.2% and 487 g DOM kg−1 DM, respectively) were high, and similar to those found by Timenes (1986). The estimated NE content of this shrubs was moderate (4.7 MJ kg−1 DM), with the highest content in the winter cuts and the lowest in the summer cuts. The results of this research suggest that 1 kg DM of R. lunaria almost covers the requirements reported by INRA (1988) for maintenance of 50 kg-goats. 4.3. Acacia salicina and Cassia sturtii These two shrubs had the lowest crude protein content (mean 10–12%), with the highest content in winter cuts. The fibre content was moderate (about 400 g NDF kg−1 DM), but with a relatively high lignification (25% of NDF was ADL). Both species had tannins; other authors (Hall et al., 1972) also reported a similar content of tannins in A. salicina. Moreover, A. salicina had the highest Ca content of the studied forages. Organic matter and protein degradability of A. salicina (33.5 and 30.4%, respectively) was the lowest of the analysed species, while the degradability of C. sturtii was moderate (53.5 and 56.4%, respectively). Organic matter in vitro digestibility and DOM content of these shrubs were the lowest of the analysed forages, probably because of the negative effects of tannins on digestibility (Silanikove et al., 2001), and lower than the values reported by Silva et al. (1986) for A. salicina. Therefore, the mean NE content of these shrubs was low (3.2–3.3 MJ kg−1 DM), particularly in the spring cuts. The results of this research suggest that more than 1.5 kg DM of these shrubs are needed to cover the energy and protein require-
17
ments reported by INRA (1988) for maintenance of 50 kg-goats. However, the tannin content could affect the voluntary intake of these shrubs.
Acknowledgements The authors wish to acknowledge to Edu Molina for skilled technical assistance from Zaidin Research Centre, Granada, and Pilar Mendez from CITA, Tenerife.
References AOAC, 1990. Official Methods of Analysis, 15th ed. Association of Official Analytical Chemists, Arlington, VA. Ganev, G., Orskov, E.R., Smart, R., 1979. The effect of roughage or concentrate feeding and rumen retention time on total degradation of protein in rumen. J. Agric. Sc. 93, 651–656. Hall, N., Boden, R., Christian, C.S., Condon, R., 1972. The use of trees and shrubs in the dry country of Australia. Australian Government Public Service. Camberra. Houerou, H.N., 1980. Browse in Northern Africa. International Livestock Centre for Africa, Addis Abeba. INRA, 1988. Alimentation des bovins, ovins et caprins. Institute National de la Reserche Agronomique, Paris. MAFF, 1984. Energy allowances and feeding systems for ruminants. Reference Book 433. Ministry of Agriculture, Fisheries and Food, London. Mendez, P., 1992. Evaluación de forrajes endémicos de Canarias. In: Proceedings of the XXXII Symposium of the Spanish Society for Grassland Research. Pamplona, Spain. Mendez, P., Fernandez, G., 1990. Especies arbustivas canarias como forraje para zonas aridas y semiaridas. In: Proceedings of the International Symposium on goat farming in arid zones. Coquimbo, Chile. Orskov, E.R., McDonald, I., 1979. The estimation of protein degradability in the rumen from incubation measurements weighted according to rate of passage. J. Agric. Sci. 92, 499– 503. Price, M.L., Van Scoyoc, S., Butler, L.G., 1978. A critical evaluation of the vanilin reaction as an assay for tannin in sorghum grain. J. Agric. Food Chem. 26, 1214–1218. Rodr´ıguez, M.M., Rivas, M.V., Rosiles, M.R., 1985. Niveles de oxalatos en forrajes silvestres. Veterinaria, Mexico, p. 16. SAS, 1989. SAS User’s Guide: Statistics. SAS Institute, Inc., Cary, NC. Sauvant, D., Morand-Fehr, P., 1991. Energy requirements and allowances of adults goats. In: Morand-Fehr, P. (Ed.), Goat Nutrition. PUDOC, Wageningen, pp. 61–72. Silanikove, N., Perevolotsky, A., Provenza, F.D., 2001. Use of tannin-binding chemicals to assay for tannins and their negative post-ingestive effects in ruminants. Anim. Feed Sci. Technol. 91, 69–81.
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M.R. Ventura et al. / Small Ruminant Research 52 (2004) 13–18
Silva, J.H., Molina, E., Fonolla, J., Boza, J., 1986. Digestibility of Atriplez nummularia and Acacia salicina in goats. Nutrition and alimentation des caprins. Nancy, France. Tilley, J.M.A., Terry, R.A., 1963. A two stage technique for in vitro digestion of forage crops. J. Br. Grassland Soc. 18, 104–111. Timenes, K., 1986. Chemical composition and digestibility of some grass and weed species. Forskning og Forsok i Landbruket 37, 1–7.
Van Soest, P.J., Robertson, J.B., Lewis, B.A., 1991. Methods for dietary fibre, neutral detergent fibre and nonstarch polysaccharides in relation to animal nutrition. J. Dairy Sci. 74, 3583–3597. Ventura, M.R., 1997. Valor nutritivo de arbustos forrajeros. Ph.D. Dissertation. University of Las Palmas de Gran Canaria, Spain.
Nutritive value of forage shrubs: Bituminaria bituminosa, Rumex lunaria, Acacia salicina, Cassia sturtii and Adenocorpus foliosus M.R. Ventura, J.I.R. Castañón∗ , M.C. Pieltain, M.P. Flores Department of Animal Science, University of Las Palmas de Gran Canaria, 35001 Las Palmas de Gran Canaria, Spain Received 27 February 2002; received in revised form 5 February 2003; accepted 4 March 2003
Abstract The nutritive value of three forage shrubs endemic from Canary Islands (Bituminaria bituminosa, Rumex lunaria, Adenocorpus foliosus) and two introduced shrubs (Acacia salicina, Cassia sturtii) was studied along the year. Mean organic matter, neutral detergent fibre and protein content (g kg−1 dry matter (DM)) of four cuts along the year was, respectively, 910, 424 and 184 for B. bituminosa, 865, 329 and 149 for R. lunaria, 955, 452 and 159 for A. foliosus, 879, 412 and 123 for A. salicina, 937, 390 and 102 for C. sturtii. Mean calcium content (kg−1 DM) was the highest for A. salicina (25.1 g), the lowest for A. foliosus (3.2 g), and moderate for the others (range 10.4–14.3 g). Mean phosphorus content of shrubs ranged 1.5–2.8 g kg−1 DM. Mean tannin content (g catequins kg−1 DM) was the highest for C. sturtii and R. lunaria (0.63 and 0.54 g, respectively) and moderate for A. salicina (0.24 g), while B. bituminosa and A. foliosus had only traces of tannins. Mean ruminal organic matter degradability, protein degradability and in vitro organic matter digestibility were, respectively, 57.5, 72.2 and 64.6% for B. bituminosa, 50.5, 57.0 and 56.2% for R. lunaria, 49.7, 55.4 and 59.6% for A. foliosus, 33.5, 30.4 and 37.4% for A. salicina, 53.5, 56.4 and 38.8% for C. sturtii. From these results, the net energy content of B. bituminosa, R. lunaria, A. foliosus, A. salicina and C. sturtii was estimated to be, respectively, 5.6, 4.7, 5.4, 3.2 and 3.3 MJ kg−1 DM, with significant differences among species and seasons. © 2003 Elsevier B.V. All rights reserved. Keywords: Bituminaria; Acacia; Rumex; Cassia; Adenocarpus; Legume shrubs; Nutritive value
1. Introduction Forage shrubs are useful forages for arid areas because of their adaptation and productivity in dry climates and poor soils. B. bituminosa, A. foliosus and R. lunaria are endemic forages shrubs from Canary Islands, and A. salicina and C. sturtii are legume browse trees used in arid zones of Africa and other areas (Houerou, 1980). Although these species have been widely used in ruminant feed, scarce research has been ∗ Corresponding author. Tel.: +34-928-451133; fax: +34-928-451142. E-mail address: [email protected] (J.I.R. Castañ´on).
carried out to determine their nutritive value (Mendez and Fernandez, 1990; Ventura, 1997). In this research, the nutritive value of these legume shrubs along the year was studied by chemical composition analyses, tannin content, ruminal degradability and in vitro digestibility trials. 2. Materials and methods Hand-samples of the different species were taken in different seasons of the year (spring—April, summer—August, autumn—November and winter— February) from shrubs in an experimental plot where
0921-4488/$ – see front matter © 2003 Elsevier B.V. All rights reserved. doi:10.1016/S0921-4488(03)00225-6
14
M.R. Ventura et al. / Small Ruminant Research 52 (2004) 13–18
all the species were grown under the same climatic conditions: 300–400 mm mean annual rainfall, 19.3 ◦ C mean annual temperature, 6 ◦ C minimum winter temperature and 220 mm highest summer evapotranspiration. Each sample consisted of leaves and thin stems (less than 3 mm of diameter) of the shrubs. The samples were air-dried to constant weight in a fan-assisted oven at 60 ◦ C for 2 days and then they were ground to pass through a 1 mm sieve. Dry matter (DM), ash, minerals and crude protein (CP) were analysed according to standard methods (AOAC, 1990). Detergent fibres and acid detergent lignin were analysed according to Van Soest et al. (1991). A mixture of samples from different seasons was analysed to determine the ether extract (EE) content according to AOAC (1990) and the condensed tannin content of each shrub by the modified vanillin method (Price et al.,
1978) using a Pye-Unicam SP6-550 spectrophotometer. Ruminal organic matter and crude protein degradability was determined using nylon bags with four fistulated adult Canarian male goats, fed at maintenance level with a mixture of shrubs ad libitum and 200 g whole maize grain (100 g twice daily) during the entire 15 days experimental period (3 days to assess each shrubs). Duplicate bags with 3 g sample were incubated for 0, 6, 18, 24, 48 and 72 h in the rumen of each goat according to Ganev et al. (1979). Effective degradability was determinated according to Orskov and McDonald (1979), using the GLM procedure (SAS, 1989) and assuming 0.04 h−1 as the theoretical passage rate (INRA, 1988). Dry and organic matter in vitro digestibilities of duplicate samples was determined using the two-stage technique (Tilley and Terry, 1963).
Table 1 Chemical composition (g kg−1 DM) of shrubs
B. bituminosa
R. lunaria
A. salicina
C. sturtii
A. foliosus
Time
DM
OM
Spring Summer Autumn Winter
311 266 270 247
Mean
274 ± 23
910 ± 13
184 ± 18
424 ± 36
296 ± 52
73 ± 18
Spring Summer Autumn Winter
373 332 181 144
874 826 875 885
122 108 183 181
328 232 374 381
290 165 280 275
78 82 83 81
Mean
258 ± 97
865 ± 23
149 ± 34
329 ± 60
252 ± 51
Spring Summer Autumn Winter
317 347 338 351
910 863 862 879
133 90 128 142
499 330 402 416
302 232 305 256
Mean
338 ± 13
879 ± 19
123 ± 20
412 ± 60
274 ± 31
102 ± 9
Spring Summer Autumn Winter
399 615 446 323
947 926 934 941
75 87 117 130
349 389 393 428
206 274 297 237
69 91 86 104
Mean
446 ± 97
937 ± 8
102 ± 22
390 ± 28
254 ± 35
88 ± 13
Spring Summer Winter
494 a,b 544 a 438 b
952 955 957
160 a,b 136 b 182 a
453 a,b 485 a 419 b
319 a 327 a 256 b
98 80 83
Mean
492 ± 43
955 ± 2
159 ± 19
452 ± 27
300 ± 32
87 ± 8
a a,b a,b b
a a b b
b a a a
b,c a b c
915 911 890 925
CP a,b a,b b a
a b a a
a b b a,b
198 159 204 173
a b a a,b
b b a a
a b a a
b b a a
NDF
ADF
ADL
380 417 481 416
256 323 368 238
52 59 82 98
b a,b a a,b
a,b b a a
a c b b
b a,b a,b a
b a a b
a b a a
a b a b
b a a b
Means with different letters (a, b and c) in the same column of each shrub differ significantly (P < 0.05).
b b a,b a
81 ± 2 88 103 113 102
EE
29 ± 5.4
28 ± 4.3
b a,b a a,b 23 ± 6.2
c a,b b,c a 21 ± 3.4
20 ± 2.3
M.R. Ventura et al. / Small Ruminant Research 52 (2004) 13–18
Based on digestible organic matter (DOM) content of forages, metabolizable energy (ME, MJ kg−1 DM) content of the shrubs was estimated as 0.015 × DOM (MAFF, 1984). The net energy for lactation (NE) content was calculated using the ratio NE/ME = 0.60 (Sauvant and Morand-Fehr, 1991), where ME is the metabolizable energy content of the feed. The effects of season on the chemical composition and the nutritive value of each shrubs were compared by LSD tests (SAS, 1989), and a level of P < 0.05 was chosen as the minimum for statistical significance.
3. Results Chemical composition of browse samples is shown in Table 1. Mean nutrient contents of forages were 35.6% DM (range 14.4–61.5%), 909 g OM kg−1 DM (range 826–957), and 401 g NDF kg−1 DM (range 232–499), with significant differences among species
15
and seasons. Mean crude protein content of shrubs was 143 g kg−1 DM (range 75–204). Mineral and tannin contents of forages are shown in Table 2. Mean mineral contents of shrubs, per kg DM, were 13.3 g Ca (range 2.3–34.8) and 2.1 g P (range 1.2–3.3). The highest tannin content was found in R. lunaria and C. sturtii, while B. bituminosa and A. foliosus had only traces of tannins. Ruminal degradability of organic matter and crude protein are shown in Table 3. Mean organic matter degradability of forages was 48.9% (range 29.4–67.5%), and mean protein degradability was 54.3% (range 24.3–77.6%). Mean organic matter in vitro digestibility (IVOMD) of shrubs was 51.3% (range 24.9–68.2%). Estimated net energy content (Table 3) of forages ranged 2.1–6.0 MJ NE kg−1 DM, with significant differences among species and seasons, with the highest values for B. bituminosa and A. foliosus, and the lowest values for A. salicina and C. sturtii.
Table 2 Mineral (g kg−1 DM) and tannin contents (g catequins kg−1 DM) of shrubs
B. bituminosa
R. lunaria
A. salicina
C. sturtii
A. foliosus
Time
Ca
P
Spring Summer Autumn Winter
11.3 10.6 11.0 8.6
2.6 2.5 3.1 3.2
2.2 1.8 2.6 1.6
Mean
10.4 ± 1.0
2.8 ± 0.3
2.0 ± 0.4
Spring Summer Autumn Winter
13.3 17.6 11.6 14.7
1.8 1.9 2.8 3.3
Mean
14.3 ± 5.3
2.5 ± 0.6
8.2 ± 2.2
8.1 ± 5.1
31.7 ± 9.7
Summer Autumn Winter
34.8 a 17.7 b 22.7 a,b
1.6 1.3 1.5
1.0 a 1.6 a 1.3 b
4.5 3.0 3.7
19.2 15.8 15.0
Mean
25.1 ± 11
1.5 ± 0.1
1.3 ± 0.2
3.7 ± 0.6
16.6 ± 1.8
Summer Autumn Winter
11.8 b 15.8 a 12.5 b
1.2 b 2.0 a 1.9 a
1.3 1.3 1.1
4.5 a 3.5 a,b 2.8 b
18.0 a 13.8 b 15.8 a,b
Mean
13.4 ± 1.7
1.7 ± 0.4
1.2 ± 0.1
3.6 ± 0.7
15.9 ± 1.7
a,b a b a,b
Mg
b b a a
7.6 10.1 6.4 8.6
Na a,b a,b a b
b a b a,b
K
Tannins
2.5 2.4 2.7 3.0
26.6 32.2 29.3 33.3
2.6 ± 0.2
30.3 ± 2.6
12.8 6.5 7.0 6.2
a b b b
24.7 44.6 26.0 31.5
b a a,b a
b a b b
Spring Summer Winter
3.3 4.0 2.3
1.8 1.3 2.3
1.8 2.2 1.3
3.8 3.5 2.9
18.9 a 10.6 b 13.9 b
Mean
3.2 ± 0.7
1.8 ± 0.4
1.8 ± 0.4
3.4 ± 0.4
14.5 ± 4.8
Means with different letters (a, b and c) in the same column of each shrub differ significantly (P < 0.05).
0.02 ± 0.004
0.54 ± 0.02
0.24 ± 0.01
0.63 ± 0.01
0.01 ± 0.005
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M.R. Ventura et al. / Small Ruminant Research 52 (2004) 13–18
Table 3 Organic matter and protein ruminal degradability (OMD, CPD, %), in vitro dry matter and organic matter digestibility (IVDMD, IVOMD, %), digestible organic matter (DOM, g kg−1 DM) and estimated net energy content (NE, MJ kg−1 DM) of shrubs Time
OMD
CPD
B. bituminosa
Spring Summer Autumn Winter
56.2 47.7 58.7 67.5
70.5 66.5 74.2 77.6
Mean
57.5 ± 7.0
72.2 ± 4.2
67.9 ± 2.9
64.6 ± 33
588 ± 38
5.6 ± 0.3
R. lunaria
Spring Summer Autumn Winter
41.8 49.0 50.6 60.4
47.1 50.5 60.5 70.1
63 a,b 58.4 b 58.4 b 69.0 a
57.7 49.6 52.5 64.9
504 410 459 574
4.9 4.0 4.5 5.5
Mean
50.5 ± 6.6
57.0 ± 9.0
62.2 ± 4.4
56.2 ± 5.8
487 ± 61
4.7 ± 0.5
A. salicina
Spring Summer Autumn Winter
32.6 41.3 29.4 30.7
24.3 36.2 27.5 33.8
36.0 54.8 45.0 43.7
33.0 47.6 36.2 35.9
300 411 312 316
2.9 4.0 3.1 3.1
Mean
33.5 ± 4.6
30.4 ± 4.7
44.9 ± 6.8
37.4 ± 6.0
334 ± 44
3.2 ± 0.4
C. sturtii
Spring Summer Autumn Winter
53.8 49.6 54.1 56.4
44.9 52.5 62.1 66.2
28.9 40.0 52.3 49.6
24.9 35.2 48.9 46.4
236 326 457 437
2.1 3.0 4.2 4.0
Mean
53.5 ± 2.4
56.4 ± 8.3
42.7 ± 9.4
38.8 ± 9.6
364 ± 83
3.3 ± 0.6
A. foliosus
Spring Summer Winter
45.8 b 45.8 b 57.5 a
49.3 b 52.4 b 64.4 a
60.9 60.1 63.5
58.9 58.2 61.7
561 b 556 b 590 a
5.3 b 5.3 b 5.6 a
Mean
49.7 ± 5.5
55.4 ± 6.5
61.5 ± 1.7
59.6 ± 1.5
569 ± 15
5.4 ± 0.1
b c b a
c b b a
b a b b
a,b b a,b a
b,c c a,b a
c c b a
b a b a
c b,c a,b a
IVDMD
IVOMD
DOM
NE
68.2 68.9 63.7 70.6
65.1 65.9 59.2 68.2
595 600 527 631
5.7 5.7 5.1 6.0
a,b a,b b a
c a b b,c
c b a a
a a b a
a,b c b,c a
b a b b
b b a a
a a b a
a,b c b,c a
b a b b
c b a a
a a b a
a,b c b,c a
a a b b
c b a a
Means with different letters (a, b and c) in the same column of each shrub differ significantly (P < 0.05).
4. Discussion 4.1. Bituminaria bituminosa and Adenocarpus foliosus These two shrubs had the highest crude protein content of the studied forages (mean 16–18%), with the lowest content in the summer cuts. The fibre content of these forages also was the highest (more than 400 g NDF kg−1 DM), but it was a low lignificated fibre (less than 20% of NDF was ADL). Only traces of tannins were found in these species. The main differences between these two forages was the DM content and the low calcium content of A. foliosus. Organic matter and protein degradability of B. bituminosa (57.5 and 72.2%, respectively) was the highest of the studied species, while the degradability of
A. foliosus nutrients was moderate (49.7 and 55.4%, respectively). Organic matter in vitro digestibility and DOM content of these species (60–65% and more than 550 g DOM kg−1 DM, respectively) were also the highest. Therefore, the mean NE content of these shrubs was high (mean 5.5 MJ kg−1 DM), similar to that estimated by Mendez (1992), with the highest content in winter cuts. The results of this research suggest that 1 kg DM of these shrubs could cover the energy and protein requirements reported by INRA (1988) for maintenance of 50 kg-goats. 4.2. Rumex lunaria R. lunaria had the lowest DM content (25.8%) of the shrubs, particularly the autumn and winter cuts. The protein content of this forage was high (18%) in
M.R. Ventura et al. / Small Ruminant Research 52 (2004) 13–18
autumn and winter cuts, and moderate (11–12%) in the other seasons. Fibre content of R. lunaria was the lowest (329 g NDF kg−1 DM) of the studied shrubs, but with a relatively high lignification (25% of NDF was ADL). The content of some minerals (Mg, Na and K) was the highest of the analysed shrubs. Some authors (Rodr´ıguez et al., 1985) have reported that R. lunaria contains oxalates, which could reduce the digestibility of some minerals, particularly calcium. Organic matter and protein degradability of R. lunaria were 50.5 and 57.0%, respectively. Although R. lunaria had a relatively high tannin content (0.54 g catequins kg−1 DM), organic matter in vitro digestibility and DOM content (56.2% and 487 g DOM kg−1 DM, respectively) were high, and similar to those found by Timenes (1986). The estimated NE content of this shrubs was moderate (4.7 MJ kg−1 DM), with the highest content in the winter cuts and the lowest in the summer cuts. The results of this research suggest that 1 kg DM of R. lunaria almost covers the requirements reported by INRA (1988) for maintenance of 50 kg-goats. 4.3. Acacia salicina and Cassia sturtii These two shrubs had the lowest crude protein content (mean 10–12%), with the highest content in winter cuts. The fibre content was moderate (about 400 g NDF kg−1 DM), but with a relatively high lignification (25% of NDF was ADL). Both species had tannins; other authors (Hall et al., 1972) also reported a similar content of tannins in A. salicina. Moreover, A. salicina had the highest Ca content of the studied forages. Organic matter and protein degradability of A. salicina (33.5 and 30.4%, respectively) was the lowest of the analysed species, while the degradability of C. sturtii was moderate (53.5 and 56.4%, respectively). Organic matter in vitro digestibility and DOM content of these shrubs were the lowest of the analysed forages, probably because of the negative effects of tannins on digestibility (Silanikove et al., 2001), and lower than the values reported by Silva et al. (1986) for A. salicina. Therefore, the mean NE content of these shrubs was low (3.2–3.3 MJ kg−1 DM), particularly in the spring cuts. The results of this research suggest that more than 1.5 kg DM of these shrubs are needed to cover the energy and protein require-
17
ments reported by INRA (1988) for maintenance of 50 kg-goats. However, the tannin content could affect the voluntary intake of these shrubs.
Acknowledgements The authors wish to acknowledge to Edu Molina for skilled technical assistance from Zaidin Research Centre, Granada, and Pilar Mendez from CITA, Tenerife.
References AOAC, 1990. Official Methods of Analysis, 15th ed. Association of Official Analytical Chemists, Arlington, VA. Ganev, G., Orskov, E.R., Smart, R., 1979. The effect of roughage or concentrate feeding and rumen retention time on total degradation of protein in rumen. J. Agric. Sc. 93, 651–656. Hall, N., Boden, R., Christian, C.S., Condon, R., 1972. The use of trees and shrubs in the dry country of Australia. Australian Government Public Service. Camberra. Houerou, H.N., 1980. Browse in Northern Africa. International Livestock Centre for Africa, Addis Abeba. INRA, 1988. Alimentation des bovins, ovins et caprins. Institute National de la Reserche Agronomique, Paris. MAFF, 1984. Energy allowances and feeding systems for ruminants. Reference Book 433. Ministry of Agriculture, Fisheries and Food, London. Mendez, P., 1992. Evaluación de forrajes endémicos de Canarias. In: Proceedings of the XXXII Symposium of the Spanish Society for Grassland Research. Pamplona, Spain. Mendez, P., Fernandez, G., 1990. Especies arbustivas canarias como forraje para zonas aridas y semiaridas. In: Proceedings of the International Symposium on goat farming in arid zones. Coquimbo, Chile. Orskov, E.R., McDonald, I., 1979. The estimation of protein degradability in the rumen from incubation measurements weighted according to rate of passage. J. Agric. Sci. 92, 499– 503. Price, M.L., Van Scoyoc, S., Butler, L.G., 1978. A critical evaluation of the vanilin reaction as an assay for tannin in sorghum grain. J. Agric. Food Chem. 26, 1214–1218. Rodr´ıguez, M.M., Rivas, M.V., Rosiles, M.R., 1985. Niveles de oxalatos en forrajes silvestres. Veterinaria, Mexico, p. 16. SAS, 1989. SAS User’s Guide: Statistics. SAS Institute, Inc., Cary, NC. Sauvant, D., Morand-Fehr, P., 1991. Energy requirements and allowances of adults goats. In: Morand-Fehr, P. (Ed.), Goat Nutrition. PUDOC, Wageningen, pp. 61–72. Silanikove, N., Perevolotsky, A., Provenza, F.D., 2001. Use of tannin-binding chemicals to assay for tannins and their negative post-ingestive effects in ruminants. Anim. Feed Sci. Technol. 91, 69–81.
18
M.R. Ventura et al. / Small Ruminant Research 52 (2004) 13–18
Silva, J.H., Molina, E., Fonolla, J., Boza, J., 1986. Digestibility of Atriplez nummularia and Acacia salicina in goats. Nutrition and alimentation des caprins. Nancy, France. Tilley, J.M.A., Terry, R.A., 1963. A two stage technique for in vitro digestion of forage crops. J. Br. Grassland Soc. 18, 104–111. Timenes, K., 1986. Chemical composition and digestibility of some grass and weed species. Forskning og Forsok i Landbruket 37, 1–7.
Van Soest, P.J., Robertson, J.B., Lewis, B.A., 1991. Methods for dietary fibre, neutral detergent fibre and nonstarch polysaccharides in relation to animal nutrition. J. Dairy Sci. 74, 3583–3597. Ventura, M.R., 1997. Valor nutritivo de arbustos forrajeros. Ph.D. Dissertation. University of Las Palmas de Gran Canaria, Spain.