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Browsing ability and utilization by sheep and goats of Atriplex halimus L. shrubs
Small Ruminant Research ELSEVIER
Small Ruminant Research 19 (1996) 131-136
Browsing ability and utilization by sheep and goats of Atriplex halimus L. shrubs J. Valderrhbano*, F. Mufioz, I. Delgado Unidad de Tecnologia en Produccidn Animal, Servicio de Investigaci6n Agraria, Apartado 727, Zaragoza 50080. Spain
Accepted 20 March 1995
Abstract A study was conducted in the Ehro valley in Spain to evaluate the utilization and intake of Atriplex hulimus grazed by ewes and goats, as well as bush regrowth after 12 months of grazing. Ten Rasa Aragonesa ewes and ten Blanca Celtib&ica goats were allowed to browse an identical number (587) of A. halimus bushes for 5 weeks at a stocking density of 20 heads ha-‘. Measurements were made of height (h) and width (d) of every hush before and after grazing and 12 months later to evaluate regrowth next season. Forage DM of bushes (y) was related to its volume (x= P[ 1/2d] *h) by the equation y(g) =337.5X (m3) + 162.37 (r=O.92 ***) that was used to estimate forage availability. Patterns of forage utilization were similar for goats and ewes, being 61% and 59% the level of utilization, respectively, after 4 weeks grazing. Differences in level of DM intake of goats ( 1430 g day-‘) and ewes ( 1310 g day-‘) were not significant. Reduction in volume of bushes consumed by goats (0.563 m3) was higher (P
1. Introduction Chenopodium shrubs have recently received increased interest as valuable revegetation species in areas of low rainfall. Saltbushes (Atriplex spp.) produce considerable amounts of biomass that can be utilized when herbaceous forage is scarce (Ostyina et al., 1984). While the nutritive value of saltbushes has been questioned by Mckell ( 1975) and Wilson and Harring* Correspondingauthor. 0921-4488/96/$15.00 0 1996 Elsevier Science B.V. All rights reserved SSDIO921-4488(95)00754-7
ton ( 1980), their N content can be as high as 2.5-3.5% of DM (Correal et al., 1986; Le HouCrou, 1992)) which could make them useful protein supplements when grasses mature, if palatable. Atriplex halimus is found in semi-arid environments in the Mediterranean basin (Gonzalez Aldama and Allue Andrade, 1972) and is valued as livestock forage when herbage availability is low (Le Hout5ou, 1992). A comparative study of palatability of Atriplex spp. of different origin showed that A. halimus was similar to Atriplex nummularia (Elhamrouni and Sarson, 1975). Palatability of A. halimus (INI& 70100) was
I32
J. Valderrdbano et ai. /Small Ruminanr Research I9 (1996) 131-136
better than any other of 14 Atriplex spp. tested and was considered a promising forage plant for large-scale plantings. However, while a number of Afriplex spp. have been reported to be very sensitive to grazing (Le Houerou, 1992), no information is available on the susceptibility of A. halimus to damage by stock. Experimental support for A. halimus comes principally from chemical analyses of browse (Wiiis et al., 1990; Alegre et al., 1994) and from pen feeding trials (Otal and Correal, 1991) but there is little production evidence from grazing animals. A study of the level of utilization and intake of A. halimus by ewes and goats and of regrowth after grazing was made within a programme to examine the use ofA. halimus for improving rangeland productivity and utilization in the Mediterranean basin.
2. Materials and methods The experiment was carried out at the Servicio de Investigaciones Agrarias in the Ebro valley in Spain (41”7’N, 1”W) at 225 m above sea level. The climate is semi-arid, with an average annual precipitation of 304.8 mm (x=326 mm, n=lO years). The mean annual temperature in the study area is 14.9 “C with a range of the minimum and maximum mean from - 6°C (February) to 39°C (July). Ten multiparous and dry Rasa Aragonesa ewes and 10 dry Blanca Celtiberica female goats with pretrial live weights (BW) of 43.25 1.34 kg and 51.2f 1.32 kg, respectively, were used. All ewes and goats were managed as a flock and grazed on fescue (Festuca arundinacea) and cereal stubbles under grazing conditions for the previous spring and summer, having no previous experience on A. halimus shrubs. Both groups of animals were dosed with an anthelmintic and were offered ryegrass (Lolium multiflorum) hay for 1 week before being transferred (on November 5) to the experimental areas where they were allowed to browse an identical number (587) of A. halimus bushes for 5 weeks at a stocking density of 20 heads ha-‘. The year before, A. halimus bare root plants, 8 month old, were transplanted in rows with spacing of 3 X 1.5 m*. The paddocks have loam soils with a pH of 8.13 and an electrical conductivity of the 1:5 (soil/water) soil extract of 0.7 dS m-i.
Measurements of the maximum height and width of every bush in each treatment paddock were taken at the beginning and end of the experiment and after 12 months to evaluate regrowth after grazing. To estimate the evolution of forage mass without compromising forage availability by removing too much grazing material, 36 bushes evenly distributed in paddocks were identified and sequentially sampied. Forage availability and level of utilization were established by collecting, by hand stripping, all the fruits and leaves plus succulent stems (of approx. 3 mm diameter) of six bushes per treatment before letting the animals in and then of three bushes per treatment at weekly intervals for the following 4 weeks. Fruits and leaves plus twigs of every sampled plant were collected separately, weighed and dried at 60°C for 48 h. Browsing ability was estimated by measuring the diameter of the six thickest twigs eaten by ewes and goats on 21 bushes selected at random in each treatment. The voluntary intake of A. halimus was calculated from faecal outputs of six ewes and six goats by the chromic oxide dilution technique and in vivo determination of the DM digestibility (Le Du and Penning, 1982) _Twice daily, at 08:OO h and 16:OOh, all the ewes and goats were dosed with a single gelatin capsule containing 0.993 f 0.009 g Crz03 in oil suspension. Chromic oxide was measured (Francois et al., 1978) in samples of faeces coliected from the rectum twice daily at the time of dosing for 5 consecutive days in Week 4 of the experiment. The marker administration began 7 days before the faecal collection period. In vivo digestibility was measured on four ewes and four goats that were removed from the paddocks after 18 days grazing on A. halimus and allocated to digestibility crates for 10 days before being returned to their paddocks. Entire branches of A. halimus (approx. 8 mm diameter) collected fresh daily were offered to the animals three times per day. For the final 6 days, herbage offered, uneaten food and faeces were recorded and sampled. Aliquot samples of the total faeces produced in the collection period were retained for a Cr,O, correction factor to be calculated for use on estimates of faecal output for the grazing animals. Samples were dried at 60°C and chemical analyses carried out according to the AOAC ( 1990). Both ewes and goats were weighed at the beginning and end of the experiment, 3 days after the animals had
J. Valderrdbano
et al. /Small
been put on treatment and then at 14-day intervals throughout the experiment. Weight gain was established from BW variation of the six ewes and six goats that remained continuously grazing for 35 days on A. halimus. During the experiment all animals had free access to water and mineral blocks. Mean size of bushes, intake and BW gain of both groups of animals were compared by Student’s t-test.
3. Results To estimate forage availability, regressions of forage DM of the bushes sampled against different parameters related to the dimensions of the bushes were derived. A regression equation of forage DM (y) upon its volume (n = Z-[ 1/2d] *II) (estimated as a theoretical cylinder from mean diameter (d) and height (h) of each individual plant) at initiation of the grazing trial was used, since it provided the best fit of the regression. The equation was: y(g) =337.5x
(m”) + 162.37
(r=O.92***)
From this equation, the mean forage DM per bush offered was 817.4k9.81 g. The pattern of forage utilization established from differences between the estimated amount of forage DM on offer and the actual DM measured on the bushes sampled at weekly intervals was similar for ewes and goats (Fig. 1), showing an increase in Week 3 of twice that found in Week 2 of the experiment. The level of utilization for goats and ewes was at 6 1.4% and 59%, respectively, after 4 weeks grazing. Utilization (XI) 701
1
2
3
4
Grazing week (In week 4, there were 6 tirmlslpaddock)
Fig
1.Pattern of A. halimus utilization by ewes and goats.
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Ruminant Research 19 (1996) I3I-I36
Table 1 Mean daily intakes, weight changes of ewes and goats, mean volume reduction and diameter of twigs eaten Goats
Ewes
SED
Level of significance
Mean
volume reduction of bushes ( m') Diameter of twigs eaten (mm ) DM intake (g day-‘) BW gain (g day-‘)
0.27 2.12 1310 5.7
I
0.563 4.58 1430 11.4
0.1158 0.267 203.1 1.18
PiO.001 P < 0.001 NS NS
While no difference was found between either paddock in the dimensions of the bushes before and after grazing, the final diameter and height of the bushes browsed by goats (d= 1361b5.10 cm; h=88-t2.48 cm) tended (P > 0.05) to be smaller than those consumed by ewes (d = 143 + 4.27 cm; h = 93 + 2.43 cm). However, when volumes were calculated from the initial and final dimensions, the mean reduction in size of the bushes browsed by goats (0.563 m3) was greater (P
134
variations
J. Valderrdbano et al. /small Ruminant Research 19 (19%) 131-136
either for ewes or goats after 5 weeks on A.
halimus (Table 1) .
4. Discussion The pattern of forage utilization (Fig. 1) shows an important increase in the level of utilization between Weeks 2 and 3 of grazing on A. halimus, suggesting that after this period the animals were fully adapted to the diet. The decrease in forage utilization in Week 4 in respect of the previous tendency was caused by the 40% reduction in the number of grazing animals which were transferred to digestibility crates. The significant differences found in mean volume reduction of bushes as in mean size of the twigs suggest that goats consumed more ligneous material than ewes. Goats are generally considered to have a better browsing ability than sheep (Wilson, 1969; Garmo et al., 1993), though their estimated intakes do not always support such an assumption (Wilson, 1977). Plant dimensions recovered after 12 months grazing, suggesting that A. halimus is tolerant of high grazing pressures for short periods of time at fruit bearing stage, in autumn. Browsing appeared to be mainly of annual regrowth, allowing the animals access again to the forage produced in the following season. Susceptibility of Afriplex spp. to damage by stock seems to be species related. While Atriplex cinerea and Atriplex lentiformis, among others, have been reported to be very sensitive to grazing (Le Houerou, 1992), Atriplex canescens appeared to recover well after defoliation (Rumbaugh et al., 1982). The chemical composition and digestibility of A. halimus were within the values reported for other Atriplex sp. (Wilson, 1977; Correal et al., 1986; Garza and Fulbright, 1988). Differences in apparent DM digestibility for sheep (44.0%) and goats (5 1.5%) were not significant (P < 0.1) .The particular characteristics of the food and its presentation as entire branches allowed the animals a selection of the diet on offer. This was, most probably, responsible for the variability in the in vivo values found among animals. While variability in in vivo digestibility values, as a consequence of selection, makes difficult the interpretation of the nutritive value of a particular forage, it may be accepted as representative of the animals’ behaviour under grazing. While information on the comparative ability to digest
ligneous material between ewes and goats is not available from this experiment, previous results suggest that goats are more capable than sheep of using cell-wall rich forages (Wilson, 1977; Tisserand et al., 1991). A reasonable intake of A. hulimus was recorded in this experiment. The 28-30 g DM per kg BW of A. halimus consumed in the fourth week of the experiment compare with recorded intakes of medium quality lucerne by Rasa Aragonesa ewes in autumn of 31 g DM per kg BW per day (Ramon et al., 1993). This result contrasts with the low values of voluntary intake of Atriplex sp. frequently found even in species of higher digestibility, such as A. nummularia, which have been attributed to its high mineral content having a negative effect on voluntary intake (Leigh and Mulham, 1967; Wiley, 1982). These conflicting results can be due to the experimental conditions, since many of the trials were carried out under pen feeding conditions which may also have affected the estimation of voluntary intake as seems to be the case for the more traditional forages (Valderrabano et al., 1986) and bushes (Wilson and Harrington, 1980). In these indoor conditions, the period of adaptation to an A. nummularia diet had to be increased to 7 weeks (Belmonte et al., 1990) to reach a level of intake similar to the level found for A. halimus in this experiment. The 138 g CP and the 7.5 MJ ME per kg of DM consumed, estimated from the A. halimus digestibility (Ministry of Agriculture, Fisheries and Food, 1975), would largely meet the maintenance requirements of the animals (ARC, 1980; Haenlein, 1989). The lack of effect on BW gain suggests that a diet of A. halimus may be used to maintain sheep and goats without an energy supplement until animal requirements are higher and require supplementation due to pregnancy and milk production.
Acknowledgements The authors thank F. Lahoz and J. Perez Revuelto for assistance with the field work. This work has been supported by a INIA project No. SC93-052.
References Alegre, J., Sancha, J.L., Guerrero, A. and Yebcnes, L., 1994. Caracterizaci6n nutritiva de arbustos forrajeros: 2 Digestibilidad e
J. Valderrdbano et al. /Small Ruminant Research 19 (1996) 131-136
ingesti6n. (Nutritive value of forage shrubs: 2. Digestibility and intake). Proc. 18th Meet. SEOC. 23-25 Sept. 1993, Albacete, Spain. Universidad Castilla-La Mancha, Cuenca, pp. 307-312. AOAC. 1990. Official Methods of Analysis. AOAC, Washington, DC, pp. 69-88. ARC, 1980. The Nutrient Requirements of Ruminant Livestock. Commonwealth Agricultural Bureaux, Slough, 35 1 pp. Belmonte, C.. OtaI. J. and Correal, E., 1990. Determinacidn de la capacidad de ingestion de Atriplex nummularia por ovejas segurerias estabuladas en boxes. (Voluntary intake of oldman saltbush by Segureha ewes kept in individual pens). Proc. XXX Reunion Cientifica de la SEEP, 4-8 June 1990, San Sebastian, Spain. Pastas, Bilbao, pp. 363-370. Correal, E., Silva-Colomer, J., Boza, J. and Passera, A.C., 1986. Valor nutritive de cuatro arbustos forrajeros de1 genero Atriplex -A. nummularia, A. cynerea, A. undulata y A. lampa-. (Nutritional value of four fodder shrubs from the genus Atriplex -A. nummulario. A. qnerea, A. unduhra and A. lampa-). Pastos, 16: 177-189. Elhamrouni. A. and Sarson, M. 1975. Appetabilitedes certains Atriplex spontanes ou introduits en Tunisie. (Grazing preferences of sheep for some indigenous and exotic species of Atriplex in Tunisia). Note de Recherche 8, Institute National de Recherches Forestiers, 10 pp. Francois, E., Thill, N. and Thewis, A., 1978. Methode rapide de dosage de l’oxyde de chrome dans les aliments, les feces et les contenus degestifs par titrage apres oxydation nitro-perchlotique. (A rapid volumetric method for the determination of chromium sesquioxide in feeds, faeces and digesta after nitroperchloric digestion). Ann. Zootech. 27: 355-361. Garmo, T.H., Hansen, H.H. and Skjevdal, T., 1993. Use of small ruminants to maintain environments in nordic countries. 44th Meeting E.A.AP., 16-19 August 1993, Aarhus, Denmark. EAAP, Roma, pp. 2 12-2 13. Garza, A. and Fulbtight, T.E., 1988. Comparative chemical composition of armed saltbush and fourwing saltbush. J. Range Manage., 41: 401403. Gonzalez Aldama, A. and Allue Andrade, J.L., 1972. Especies letiosas, de inter& pascfcola. 2 Orzaga Atriplex halimus L. (Ligneous plants of pastoral interest. 2 Orzaga Atriplex halimus L.). Monografias INIA de especies leriosas, Institute National de Investigaciones Agrarias, 35 pp. Haenlein, G.F.W., 1989. Dietary nutrient allowances for goats and sheep. Feedstuffs, 61: 77-80. Le Du, Y.L.P. and Penning, P.D., 1982. Animal based techniques forestimating herbage intake. In: J.D. Leaver (Editors), Herbage Intake Handbook. Br. Grassl. Sot., Hurley, pp. 37-75. Le Houerou, H.N., 1992. The role of saltbushes (Atriplex spp.) in arid land rehabilitation in the Mediterranean basin: a review. Agrofor. Syst., 18: 107-148. Leigh, J.H. and Mulham, W.E., 1967. Selection of diet by sheep grazing semi-arid pastures on the Riverine plain. 3. A bladder
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saltbush (Atriplexoesicaria) pigface (Disphymaaustrale) community. Aust. J. Exp. Agric. Anim. Hush., 87: 421425. McKell, C.M., 1975. Shrubs.. a neglected resource of arid lands. Science, 187: 803-809. Ministry of Agriculture, Fisheries and Food, 1975. Energy allowances and feeding systems for ruminants. Techn. Bull. No. 33. Ministry of Agriculture, Fisheries and Food, London, 79 pp. Ostyina, R.M.. McKell, C.M., Malecheck, J.M. and Epps, G.A., 1984. Potential of Atriplex and other chenopod shrubs for increasing range productivity and fall winter grazing use. Proc. Symp. Biology Atriplex and related Chenopods. 2-6 May 1983, Provo, Utah, USA. Gen. Tech. Rep. INT-172, Ogden, UT, pp. 2155219. OtaI, J. and Correal, E., 1991. Vatiaciones estacionales de la palatabilidad y consumo por el ganado ovino de diversos arbustos forrajeros preseleccionados en el SE. espatiol. (Seasonal variations of palatability and browse intake by sheep of several fodder shrubs in Southeast Spain). Proc. XXX1 Reunion Cientifica de la SEEP, 20-24 May 199 I. Consejeriade Agricultura, Ganaderia y Pesca, Murcia, pp. 353-357. Ramon, J.P., Valderrabano, J. and Folch, J.. 1993. Reproductive performance of Rasa Aragonesa ewes mated on luceme (Medicage satica cv. Arag6n) pastures. Small Rumin. Res., 11: 323329. Rumbaugh, M.D., Johnson, D.A. and Van Epps, G.A., 1982. Forage, yield and quality in a great basin shrub and legume experiment. J. Range Manage., 35: 604-609. Tisserand. J.L.. Hadjipanayiotou, M. and Gihad, E.A.. 1991. Digestion in goats. In: P. Morand-Fehr (Editor), Goat Nutrition. EAAP Publication No. 46, Pudoc, Wageningen, pp. 46-60. Valderrabano, J., Uriarte, J. and Munoz, F., 1986. Voluntary intake, health and performance of lactating ewes fed on turnips with or without straw supplement. Anim. Prod., 42: 241-246. Wiley, ST., Swingle, R.S., Brown, W.H., Glenn,E.P.,O’Leary, J.W. and Calvin, L.B., 1982. Evaluation of two Atriplexspecies grown with hipersaline water and the effect of water leaching on their digestibility by goats. Proc. Am. Sot. Anim. Sci., 13: 12-15. Wills, B.J., Begg, J.S.C. and Brosnan, M., 1990. Forage shrubs for the South Island dry hill country: I. Afriplex halimus L. (Mediterranean saltbush).
Proc. NZ Grassld. Assoc., 52: 161-165.
Wilson, A.D., 1969. A review of browse in the nutrition of grazing animals. J. Range Manage., 22: 23-28. Wilson, A.D., 1977. The digestibility and votuntary intake of the leaves of trees and shrubs by sheep and goats. Aust. J. Agric. Res., 28: 501-508. Wilson, A.D. and Ham&ton, G.N., 1980. Nutritive value of Australian browse plants. In: H.N. Le Houeou (Editor), Browse in Africa. The current state of knowledge. Int. Symp. Browse in Africa, 8-12 April 1980, Addis Ababa, Ethiopia, ILCA, Addis Ababa, pp. 291-297.
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Resumen Valderrabano, J.. Mufioz, F. and Delgado, Rumin. Rev., 19: 131-136.
I., 1995. Browsing
ability and utilization by sheep and goats of atriplex halimus L. shrubs. Small
La capacidad de utilizacibn y nivel de ingesti6n de Atriplex ha&uu por ganado ovino y caprino asi coma la capacidad de rebrote de1 arbusto 12 meses despues del pastoreo fueron evaluados en un estudio llevado a cabo en el valle de1 Ebro. Se utilizaron 10 ovejas Rasa Aragonesa y 10 cabras Blanca Celtiberica que dispusieron de un mismo numero de arbustos (587) durante 5 semanas a una densidad de carga de 20 cabems ha-‘. Se tomaron medidas de1 diametro (d) y altura (h) de cada planta antes y despues del pastoreo y 12 meses mas tarde para valorar la capacidad de rebrote en la siguiente estacion. La produccidn de MS forrajerade 10s arbustos (.v) se relacion6 con su volumen (I= rr[ I /Zd]>h) mediante la ecuacion, ,v(R) = 337.5 X (m’) + 162.37 (r=O.92*** ) que se utihz6 para estimar la disponibilidad de forraje. La evolution de la utilization de 10s arbustos fue similar para ambas especies, resultando un nivel de utilizaci6n de1 61% y de1 59% para cabras y ovejas respectivamente, tras 4 semanas de pastoreo. Las diferencias en el nivel de ingestion entre cabras ( 1430 g dfa-‘) y ovejas ( 1310 g dfa-‘) no fue significativo. La reducci6n del volumen de 10s arbustos consumidos por las cabras (0.563 m3) fue significativamente mayor (P < 0.001) que la de 10s consumidos por las ovejas (0.27 I m?).Estos valores aparecen asociados con la section media de 10s tallos consumidos (4.58 vs 0.272 mm), utilizada coma un parametro para estimar diferencias en capacidad de ramoneo entre cabras y ovejas. Las dimensiones de 10s arbustos I2 meses despues de1 pastoreo sugieren que el A. halimus tolera bien elevadas presiones de pastoreo en otoho. El aprovechamiento de 10s arbustos. parece dirigirse principalmente hacia el rebrote anual, permitiendo el acceso de 10s animales al forraje producido en la siguiente estacion. La falta de respuesta sobre peso vivo sugiere que el A. halinus puede ser utilizado coma dieta exclusiva para mantener 10s animales sin necesidad de suplementaci6n energetica hasta que sus necesidades de gestacidn o lactation fueran mayores.
RCsumC Valderrabano, J., Mutioz, F. and Delgado, Rumin. Res., 19: 131-136.
I., 1995. Browsing
ability and utilization by sheep and goats of atriplex halimus L. shrubs. Small
Dans un etude realise dans la vallee de I’Ebre la capacite d’utilisation et le niveau d’ingestion d’Atriplex halimus par des ovins et des caprins a ete Cvaluee ainsi que la capacite de repousse d’arbustre I2 mois apres le pbturage. A telle fin ont ete utilises 10 ovins de la race Rasa Aragonesa et IO chbvres de la race Blanca Celtiberica disposant du m&me nombre d’arbustes (587) pendant 5 semaines avec une charge de 20 animaux ha- ‘. Les mesures du diametre (d) et de la hauteur (II) de chaque arbuste avant et apres le plturage et I2 mois apres leur utilisation ont CtC prises afn d’evaluer la capacite de repousse dans la saison suivante. La production de MS de fourrage des arbustes (v) a CtC relationnee avec ), utilisee pour estimer la disponibilite de fourrage. son volume (x= ~1 I /2tfj’/7) par l’equation v(g) = 337.5 X (m3) + 162.37 (r=0.92*** L’evolution de I’utilisation des arbustes fut similaire pour les deux espkes, avec un niveau d’utilisation du 61% et du 59% respectivement pour chevres et moutons, apres 4 semaines de pbturage. Les differents niveaux d’ingestion entre chevres ( 1340 g jour- ) et moutons ( 13 10 g jour-’ ) n’ont pas CtCpas significatifs. La reduction du volume des arbustes consommes par les chevres (0.563 ml) a CtCsigniticativement plus important (P < 0.00 I ) que celle des arbustes consommes par les moutons (0.27 I m’). Ces valeurs sont associes a la section moyenne des tiges consommees (4.58 vs 2.72) utilisees comme parametre pour estimer les differences dans la capacite de broutage entre chevres et moutons. Les dimensions des arbustes 12 mois apres le pdturage suggerent que le A. halimus tolere bien des intensites de plturage fortes a l’automne. L’utilisation des arbustes semble principalement orientee vers la repousse annuelle permettant I’acces des animaux au fourrage produit dans la saison suivante. Le manque d’evolution du PV suggere que I’utilisation de A. halimus peut etre exclusive sans apport de suplement energetique tant que les besoins de gestation ou de lactation des animaux ne seront plus importants.
r
Small Ruminant Research 19 (1996) 131-136
Browsing ability and utilization by sheep and goats of Atriplex halimus L. shrubs J. Valderrhbano*, F. Mufioz, I. Delgado Unidad de Tecnologia en Produccidn Animal, Servicio de Investigaci6n Agraria, Apartado 727, Zaragoza 50080. Spain
Accepted 20 March 1995
Abstract A study was conducted in the Ehro valley in Spain to evaluate the utilization and intake of Atriplex hulimus grazed by ewes and goats, as well as bush regrowth after 12 months of grazing. Ten Rasa Aragonesa ewes and ten Blanca Celtib&ica goats were allowed to browse an identical number (587) of A. halimus bushes for 5 weeks at a stocking density of 20 heads ha-‘. Measurements were made of height (h) and width (d) of every hush before and after grazing and 12 months later to evaluate regrowth next season. Forage DM of bushes (y) was related to its volume (x= P[ 1/2d] *h) by the equation y(g) =337.5X (m3) + 162.37 (r=O.92 ***) that was used to estimate forage availability. Patterns of forage utilization were similar for goats and ewes, being 61% and 59% the level of utilization, respectively, after 4 weeks grazing. Differences in level of DM intake of goats ( 1430 g day-‘) and ewes ( 1310 g day-‘) were not significant. Reduction in volume of bushes consumed by goats (0.563 m3) was higher (P
1. Introduction Chenopodium shrubs have recently received increased interest as valuable revegetation species in areas of low rainfall. Saltbushes (Atriplex spp.) produce considerable amounts of biomass that can be utilized when herbaceous forage is scarce (Ostyina et al., 1984). While the nutritive value of saltbushes has been questioned by Mckell ( 1975) and Wilson and Harring* Correspondingauthor. 0921-4488/96/$15.00 0 1996 Elsevier Science B.V. All rights reserved SSDIO921-4488(95)00754-7
ton ( 1980), their N content can be as high as 2.5-3.5% of DM (Correal et al., 1986; Le HouCrou, 1992)) which could make them useful protein supplements when grasses mature, if palatable. Atriplex halimus is found in semi-arid environments in the Mediterranean basin (Gonzalez Aldama and Allue Andrade, 1972) and is valued as livestock forage when herbage availability is low (Le Hout5ou, 1992). A comparative study of palatability of Atriplex spp. of different origin showed that A. halimus was similar to Atriplex nummularia (Elhamrouni and Sarson, 1975). Palatability of A. halimus (INI& 70100) was
I32
J. Valderrdbano et ai. /Small Ruminanr Research I9 (1996) 131-136
better than any other of 14 Atriplex spp. tested and was considered a promising forage plant for large-scale plantings. However, while a number of Afriplex spp. have been reported to be very sensitive to grazing (Le Houerou, 1992), no information is available on the susceptibility of A. halimus to damage by stock. Experimental support for A. halimus comes principally from chemical analyses of browse (Wiiis et al., 1990; Alegre et al., 1994) and from pen feeding trials (Otal and Correal, 1991) but there is little production evidence from grazing animals. A study of the level of utilization and intake of A. halimus by ewes and goats and of regrowth after grazing was made within a programme to examine the use ofA. halimus for improving rangeland productivity and utilization in the Mediterranean basin.
2. Materials and methods The experiment was carried out at the Servicio de Investigaciones Agrarias in the Ebro valley in Spain (41”7’N, 1”W) at 225 m above sea level. The climate is semi-arid, with an average annual precipitation of 304.8 mm (x=326 mm, n=lO years). The mean annual temperature in the study area is 14.9 “C with a range of the minimum and maximum mean from - 6°C (February) to 39°C (July). Ten multiparous and dry Rasa Aragonesa ewes and 10 dry Blanca Celtiberica female goats with pretrial live weights (BW) of 43.25 1.34 kg and 51.2f 1.32 kg, respectively, were used. All ewes and goats were managed as a flock and grazed on fescue (Festuca arundinacea) and cereal stubbles under grazing conditions for the previous spring and summer, having no previous experience on A. halimus shrubs. Both groups of animals were dosed with an anthelmintic and were offered ryegrass (Lolium multiflorum) hay for 1 week before being transferred (on November 5) to the experimental areas where they were allowed to browse an identical number (587) of A. halimus bushes for 5 weeks at a stocking density of 20 heads ha-‘. The year before, A. halimus bare root plants, 8 month old, were transplanted in rows with spacing of 3 X 1.5 m*. The paddocks have loam soils with a pH of 8.13 and an electrical conductivity of the 1:5 (soil/water) soil extract of 0.7 dS m-i.
Measurements of the maximum height and width of every bush in each treatment paddock were taken at the beginning and end of the experiment and after 12 months to evaluate regrowth after grazing. To estimate the evolution of forage mass without compromising forage availability by removing too much grazing material, 36 bushes evenly distributed in paddocks were identified and sequentially sampied. Forage availability and level of utilization were established by collecting, by hand stripping, all the fruits and leaves plus succulent stems (of approx. 3 mm diameter) of six bushes per treatment before letting the animals in and then of three bushes per treatment at weekly intervals for the following 4 weeks. Fruits and leaves plus twigs of every sampled plant were collected separately, weighed and dried at 60°C for 48 h. Browsing ability was estimated by measuring the diameter of the six thickest twigs eaten by ewes and goats on 21 bushes selected at random in each treatment. The voluntary intake of A. halimus was calculated from faecal outputs of six ewes and six goats by the chromic oxide dilution technique and in vivo determination of the DM digestibility (Le Du and Penning, 1982) _Twice daily, at 08:OO h and 16:OOh, all the ewes and goats were dosed with a single gelatin capsule containing 0.993 f 0.009 g Crz03 in oil suspension. Chromic oxide was measured (Francois et al., 1978) in samples of faeces coliected from the rectum twice daily at the time of dosing for 5 consecutive days in Week 4 of the experiment. The marker administration began 7 days before the faecal collection period. In vivo digestibility was measured on four ewes and four goats that were removed from the paddocks after 18 days grazing on A. halimus and allocated to digestibility crates for 10 days before being returned to their paddocks. Entire branches of A. halimus (approx. 8 mm diameter) collected fresh daily were offered to the animals three times per day. For the final 6 days, herbage offered, uneaten food and faeces were recorded and sampled. Aliquot samples of the total faeces produced in the collection period were retained for a Cr,O, correction factor to be calculated for use on estimates of faecal output for the grazing animals. Samples were dried at 60°C and chemical analyses carried out according to the AOAC ( 1990). Both ewes and goats were weighed at the beginning and end of the experiment, 3 days after the animals had
J. Valderrdbano
et al. /Small
been put on treatment and then at 14-day intervals throughout the experiment. Weight gain was established from BW variation of the six ewes and six goats that remained continuously grazing for 35 days on A. halimus. During the experiment all animals had free access to water and mineral blocks. Mean size of bushes, intake and BW gain of both groups of animals were compared by Student’s t-test.
3. Results To estimate forage availability, regressions of forage DM of the bushes sampled against different parameters related to the dimensions of the bushes were derived. A regression equation of forage DM (y) upon its volume (n = Z-[ 1/2d] *II) (estimated as a theoretical cylinder from mean diameter (d) and height (h) of each individual plant) at initiation of the grazing trial was used, since it provided the best fit of the regression. The equation was: y(g) =337.5x
(m”) + 162.37
(r=O.92***)
From this equation, the mean forage DM per bush offered was 817.4k9.81 g. The pattern of forage utilization established from differences between the estimated amount of forage DM on offer and the actual DM measured on the bushes sampled at weekly intervals was similar for ewes and goats (Fig. 1), showing an increase in Week 3 of twice that found in Week 2 of the experiment. The level of utilization for goats and ewes was at 6 1.4% and 59%, respectively, after 4 weeks grazing. Utilization (XI) 701
1
2
3
4
Grazing week (In week 4, there were 6 tirmlslpaddock)
Fig
1.Pattern of A. halimus utilization by ewes and goats.
133
Ruminant Research 19 (1996) I3I-I36
Table 1 Mean daily intakes, weight changes of ewes and goats, mean volume reduction and diameter of twigs eaten Goats
Ewes
SED
Level of significance
Mean
volume reduction of bushes ( m') Diameter of twigs eaten (mm ) DM intake (g day-‘) BW gain (g day-‘)
0.27 2.12 1310 5.7
I
0.563 4.58 1430 11.4
0.1158 0.267 203.1 1.18
PiO.001 P < 0.001 NS NS
While no difference was found between either paddock in the dimensions of the bushes before and after grazing, the final diameter and height of the bushes browsed by goats (d= 1361b5.10 cm; h=88-t2.48 cm) tended (P > 0.05) to be smaller than those consumed by ewes (d = 143 + 4.27 cm; h = 93 + 2.43 cm). However, when volumes were calculated from the initial and final dimensions, the mean reduction in size of the bushes browsed by goats (0.563 m3) was greater (P
134
variations
J. Valderrdbano et al. /small Ruminant Research 19 (19%) 131-136
either for ewes or goats after 5 weeks on A.
halimus (Table 1) .
4. Discussion The pattern of forage utilization (Fig. 1) shows an important increase in the level of utilization between Weeks 2 and 3 of grazing on A. halimus, suggesting that after this period the animals were fully adapted to the diet. The decrease in forage utilization in Week 4 in respect of the previous tendency was caused by the 40% reduction in the number of grazing animals which were transferred to digestibility crates. The significant differences found in mean volume reduction of bushes as in mean size of the twigs suggest that goats consumed more ligneous material than ewes. Goats are generally considered to have a better browsing ability than sheep (Wilson, 1969; Garmo et al., 1993), though their estimated intakes do not always support such an assumption (Wilson, 1977). Plant dimensions recovered after 12 months grazing, suggesting that A. halimus is tolerant of high grazing pressures for short periods of time at fruit bearing stage, in autumn. Browsing appeared to be mainly of annual regrowth, allowing the animals access again to the forage produced in the following season. Susceptibility of Afriplex spp. to damage by stock seems to be species related. While Atriplex cinerea and Atriplex lentiformis, among others, have been reported to be very sensitive to grazing (Le Houerou, 1992), Atriplex canescens appeared to recover well after defoliation (Rumbaugh et al., 1982). The chemical composition and digestibility of A. halimus were within the values reported for other Atriplex sp. (Wilson, 1977; Correal et al., 1986; Garza and Fulbright, 1988). Differences in apparent DM digestibility for sheep (44.0%) and goats (5 1.5%) were not significant (P < 0.1) .The particular characteristics of the food and its presentation as entire branches allowed the animals a selection of the diet on offer. This was, most probably, responsible for the variability in the in vivo values found among animals. While variability in in vivo digestibility values, as a consequence of selection, makes difficult the interpretation of the nutritive value of a particular forage, it may be accepted as representative of the animals’ behaviour under grazing. While information on the comparative ability to digest
ligneous material between ewes and goats is not available from this experiment, previous results suggest that goats are more capable than sheep of using cell-wall rich forages (Wilson, 1977; Tisserand et al., 1991). A reasonable intake of A. hulimus was recorded in this experiment. The 28-30 g DM per kg BW of A. halimus consumed in the fourth week of the experiment compare with recorded intakes of medium quality lucerne by Rasa Aragonesa ewes in autumn of 31 g DM per kg BW per day (Ramon et al., 1993). This result contrasts with the low values of voluntary intake of Atriplex sp. frequently found even in species of higher digestibility, such as A. nummularia, which have been attributed to its high mineral content having a negative effect on voluntary intake (Leigh and Mulham, 1967; Wiley, 1982). These conflicting results can be due to the experimental conditions, since many of the trials were carried out under pen feeding conditions which may also have affected the estimation of voluntary intake as seems to be the case for the more traditional forages (Valderrabano et al., 1986) and bushes (Wilson and Harrington, 1980). In these indoor conditions, the period of adaptation to an A. nummularia diet had to be increased to 7 weeks (Belmonte et al., 1990) to reach a level of intake similar to the level found for A. halimus in this experiment. The 138 g CP and the 7.5 MJ ME per kg of DM consumed, estimated from the A. halimus digestibility (Ministry of Agriculture, Fisheries and Food, 1975), would largely meet the maintenance requirements of the animals (ARC, 1980; Haenlein, 1989). The lack of effect on BW gain suggests that a diet of A. halimus may be used to maintain sheep and goats without an energy supplement until animal requirements are higher and require supplementation due to pregnancy and milk production.
Acknowledgements The authors thank F. Lahoz and J. Perez Revuelto for assistance with the field work. This work has been supported by a INIA project No. SC93-052.
References Alegre, J., Sancha, J.L., Guerrero, A. and Yebcnes, L., 1994. Caracterizaci6n nutritiva de arbustos forrajeros: 2 Digestibilidad e
J. Valderrdbano et al. /Small Ruminant Research 19 (1996) 131-136
ingesti6n. (Nutritive value of forage shrubs: 2. Digestibility and intake). Proc. 18th Meet. SEOC. 23-25 Sept. 1993, Albacete, Spain. Universidad Castilla-La Mancha, Cuenca, pp. 307-312. AOAC. 1990. Official Methods of Analysis. AOAC, Washington, DC, pp. 69-88. ARC, 1980. The Nutrient Requirements of Ruminant Livestock. Commonwealth Agricultural Bureaux, Slough, 35 1 pp. Belmonte, C.. OtaI. J. and Correal, E., 1990. Determinacidn de la capacidad de ingestion de Atriplex nummularia por ovejas segurerias estabuladas en boxes. (Voluntary intake of oldman saltbush by Segureha ewes kept in individual pens). Proc. XXX Reunion Cientifica de la SEEP, 4-8 June 1990, San Sebastian, Spain. Pastas, Bilbao, pp. 363-370. Correal, E., Silva-Colomer, J., Boza, J. and Passera, A.C., 1986. Valor nutritive de cuatro arbustos forrajeros de1 genero Atriplex -A. nummularia, A. cynerea, A. undulata y A. lampa-. (Nutritional value of four fodder shrubs from the genus Atriplex -A. nummulario. A. qnerea, A. unduhra and A. lampa-). Pastos, 16: 177-189. Elhamrouni. A. and Sarson, M. 1975. Appetabilitedes certains Atriplex spontanes ou introduits en Tunisie. (Grazing preferences of sheep for some indigenous and exotic species of Atriplex in Tunisia). Note de Recherche 8, Institute National de Recherches Forestiers, 10 pp. Francois, E., Thill, N. and Thewis, A., 1978. Methode rapide de dosage de l’oxyde de chrome dans les aliments, les feces et les contenus degestifs par titrage apres oxydation nitro-perchlotique. (A rapid volumetric method for the determination of chromium sesquioxide in feeds, faeces and digesta after nitroperchloric digestion). Ann. Zootech. 27: 355-361. Garmo, T.H., Hansen, H.H. and Skjevdal, T., 1993. Use of small ruminants to maintain environments in nordic countries. 44th Meeting E.A.AP., 16-19 August 1993, Aarhus, Denmark. EAAP, Roma, pp. 2 12-2 13. Garza, A. and Fulbtight, T.E., 1988. Comparative chemical composition of armed saltbush and fourwing saltbush. J. Range Manage., 41: 401403. Gonzalez Aldama, A. and Allue Andrade, J.L., 1972. Especies letiosas, de inter& pascfcola. 2 Orzaga Atriplex halimus L. (Ligneous plants of pastoral interest. 2 Orzaga Atriplex halimus L.). Monografias INIA de especies leriosas, Institute National de Investigaciones Agrarias, 35 pp. Haenlein, G.F.W., 1989. Dietary nutrient allowances for goats and sheep. Feedstuffs, 61: 77-80. Le Du, Y.L.P. and Penning, P.D., 1982. Animal based techniques forestimating herbage intake. In: J.D. Leaver (Editors), Herbage Intake Handbook. Br. Grassl. Sot., Hurley, pp. 37-75. Le Houerou, H.N., 1992. The role of saltbushes (Atriplex spp.) in arid land rehabilitation in the Mediterranean basin: a review. Agrofor. Syst., 18: 107-148. Leigh, J.H. and Mulham, W.E., 1967. Selection of diet by sheep grazing semi-arid pastures on the Riverine plain. 3. A bladder
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saltbush (Atriplexoesicaria) pigface (Disphymaaustrale) community. Aust. J. Exp. Agric. Anim. Hush., 87: 421425. McKell, C.M., 1975. Shrubs.. a neglected resource of arid lands. Science, 187: 803-809. Ministry of Agriculture, Fisheries and Food, 1975. Energy allowances and feeding systems for ruminants. Techn. Bull. No. 33. Ministry of Agriculture, Fisheries and Food, London, 79 pp. Ostyina, R.M.. McKell, C.M., Malecheck, J.M. and Epps, G.A., 1984. Potential of Atriplex and other chenopod shrubs for increasing range productivity and fall winter grazing use. Proc. Symp. Biology Atriplex and related Chenopods. 2-6 May 1983, Provo, Utah, USA. Gen. Tech. Rep. INT-172, Ogden, UT, pp. 2155219. OtaI, J. and Correal, E., 1991. Vatiaciones estacionales de la palatabilidad y consumo por el ganado ovino de diversos arbustos forrajeros preseleccionados en el SE. espatiol. (Seasonal variations of palatability and browse intake by sheep of several fodder shrubs in Southeast Spain). Proc. XXX1 Reunion Cientifica de la SEEP, 20-24 May 199 I. Consejeriade Agricultura, Ganaderia y Pesca, Murcia, pp. 353-357. Ramon, J.P., Valderrabano, J. and Folch, J.. 1993. Reproductive performance of Rasa Aragonesa ewes mated on luceme (Medicage satica cv. Arag6n) pastures. Small Rumin. Res., 11: 323329. Rumbaugh, M.D., Johnson, D.A. and Van Epps, G.A., 1982. Forage, yield and quality in a great basin shrub and legume experiment. J. Range Manage., 35: 604-609. Tisserand. J.L.. Hadjipanayiotou, M. and Gihad, E.A.. 1991. Digestion in goats. In: P. Morand-Fehr (Editor), Goat Nutrition. EAAP Publication No. 46, Pudoc, Wageningen, pp. 46-60. Valderrabano, J., Uriarte, J. and Munoz, F., 1986. Voluntary intake, health and performance of lactating ewes fed on turnips with or without straw supplement. Anim. Prod., 42: 241-246. Wiley, ST., Swingle, R.S., Brown, W.H., Glenn,E.P.,O’Leary, J.W. and Calvin, L.B., 1982. Evaluation of two Atriplexspecies grown with hipersaline water and the effect of water leaching on their digestibility by goats. Proc. Am. Sot. Anim. Sci., 13: 12-15. Wills, B.J., Begg, J.S.C. and Brosnan, M., 1990. Forage shrubs for the South Island dry hill country: I. Afriplex halimus L. (Mediterranean saltbush).
Proc. NZ Grassld. Assoc., 52: 161-165.
Wilson, A.D., 1969. A review of browse in the nutrition of grazing animals. J. Range Manage., 22: 23-28. Wilson, A.D., 1977. The digestibility and votuntary intake of the leaves of trees and shrubs by sheep and goats. Aust. J. Agric. Res., 28: 501-508. Wilson, A.D. and Ham&ton, G.N., 1980. Nutritive value of Australian browse plants. In: H.N. Le Houeou (Editor), Browse in Africa. The current state of knowledge. Int. Symp. Browse in Africa, 8-12 April 1980, Addis Ababa, Ethiopia, ILCA, Addis Ababa, pp. 291-297.
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.I. Valderrdbano
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Resumen Valderrabano, J.. Mufioz, F. and Delgado, Rumin. Rev., 19: 131-136.
I., 1995. Browsing
ability and utilization by sheep and goats of atriplex halimus L. shrubs. Small
La capacidad de utilizacibn y nivel de ingesti6n de Atriplex ha&uu por ganado ovino y caprino asi coma la capacidad de rebrote de1 arbusto 12 meses despues del pastoreo fueron evaluados en un estudio llevado a cabo en el valle de1 Ebro. Se utilizaron 10 ovejas Rasa Aragonesa y 10 cabras Blanca Celtiberica que dispusieron de un mismo numero de arbustos (587) durante 5 semanas a una densidad de carga de 20 cabems ha-‘. Se tomaron medidas de1 diametro (d) y altura (h) de cada planta antes y despues del pastoreo y 12 meses mas tarde para valorar la capacidad de rebrote en la siguiente estacion. La produccidn de MS forrajerade 10s arbustos (.v) se relacion6 con su volumen (I= rr[ I /Zd]>h) mediante la ecuacion, ,v(R) = 337.5 X (m’) + 162.37 (r=O.92*** ) que se utihz6 para estimar la disponibilidad de forraje. La evolution de la utilization de 10s arbustos fue similar para ambas especies, resultando un nivel de utilizaci6n de1 61% y de1 59% para cabras y ovejas respectivamente, tras 4 semanas de pastoreo. Las diferencias en el nivel de ingestion entre cabras ( 1430 g dfa-‘) y ovejas ( 1310 g dfa-‘) no fue significativo. La reducci6n del volumen de 10s arbustos consumidos por las cabras (0.563 m3) fue significativamente mayor (P < 0.001) que la de 10s consumidos por las ovejas (0.27 I m?).Estos valores aparecen asociados con la section media de 10s tallos consumidos (4.58 vs 0.272 mm), utilizada coma un parametro para estimar diferencias en capacidad de ramoneo entre cabras y ovejas. Las dimensiones de 10s arbustos I2 meses despues de1 pastoreo sugieren que el A. halimus tolera bien elevadas presiones de pastoreo en otoho. El aprovechamiento de 10s arbustos. parece dirigirse principalmente hacia el rebrote anual, permitiendo el acceso de 10s animales al forraje producido en la siguiente estacion. La falta de respuesta sobre peso vivo sugiere que el A. halinus puede ser utilizado coma dieta exclusiva para mantener 10s animales sin necesidad de suplementaci6n energetica hasta que sus necesidades de gestacidn o lactation fueran mayores.
RCsumC Valderrabano, J., Mutioz, F. and Delgado, Rumin. Res., 19: 131-136.
I., 1995. Browsing
ability and utilization by sheep and goats of atriplex halimus L. shrubs. Small
Dans un etude realise dans la vallee de I’Ebre la capacite d’utilisation et le niveau d’ingestion d’Atriplex halimus par des ovins et des caprins a ete Cvaluee ainsi que la capacite de repousse d’arbustre I2 mois apres le pbturage. A telle fin ont ete utilises 10 ovins de la race Rasa Aragonesa et IO chbvres de la race Blanca Celtiberica disposant du m&me nombre d’arbustes (587) pendant 5 semaines avec une charge de 20 animaux ha- ‘. Les mesures du diametre (d) et de la hauteur (II) de chaque arbuste avant et apres le plturage et I2 mois apres leur utilisation ont CtC prises afn d’evaluer la capacite de repousse dans la saison suivante. La production de MS de fourrage des arbustes (v) a CtC relationnee avec ), utilisee pour estimer la disponibilite de fourrage. son volume (x= ~1 I /2tfj’/7) par l’equation v(g) = 337.5 X (m3) + 162.37 (r=0.92*** L’evolution de I’utilisation des arbustes fut similaire pour les deux espkes, avec un niveau d’utilisation du 61% et du 59% respectivement pour chevres et moutons, apres 4 semaines de pbturage. Les differents niveaux d’ingestion entre chevres ( 1340 g jour- ) et moutons ( 13 10 g jour-’ ) n’ont pas CtCpas significatifs. La reduction du volume des arbustes consommes par les chevres (0.563 ml) a CtCsigniticativement plus important (P < 0.00 I ) que celle des arbustes consommes par les moutons (0.27 I m’). Ces valeurs sont associes a la section moyenne des tiges consommees (4.58 vs 2.72) utilisees comme parametre pour estimer les differences dans la capacite de broutage entre chevres et moutons. Les dimensions des arbustes 12 mois apres le pdturage suggerent que le A. halimus tolere bien des intensites de plturage fortes a l’automne. L’utilisation des arbustes semble principalement orientee vers la repousse annuelle permettant I’acces des animaux au fourrage produit dans la saison suivante. Le manque d’evolution du PV suggere que I’utilisation de A. halimus peut etre exclusive sans apport de suplement energetique tant que les besoins de gestation ou de lactation des animaux ne seront plus importants.
r