Short communication
In¯uence of alkaloid content on intake of
subspecies of
Chamaecytisus proliferus
M.R. Ventura
a, J.I.R. Castanon
a,*, M. Muzquiz
b,
P. Mendez
c, M.P. Flores
aaDepartment of Animal Science, University of Las Palmas de Gran Canaria, 35416 Arucas, Spain bArea de TecnologõÂa de Alimentos, SGIT-INIA, P.O. Box 8111, Madrid 28080, Spain cInstituto Canario de Investigaciones Agrarias, P.O. Box 60, La Laguna, Tenerife 38200, Spain
Received 27 July 1999; received in revised form 16 December 1999; accepted 24 March 2000
Abstract
Alkaloid contents (sparteine accounted for more than 80%) of four subspecies ofChamaecytisus proliferus(tagasaste) were higher in spring cuts than in autumn cuts, and they were (g kgÿ1DM for spring and autumn cuts, respectively) 2.9 and 1.6 for palmensis subspecies, 7.3 and 2.9 for
canariae, 11.3 and 7.9 formeridionalesand 2.7 for the autumn cut ofcalderae. Voluntary intake was determined by free-choosing among subspecies cuts. Intake of tagasaste subspecies ranged between 3.7 and 9.2 g DM kgÿ1
BW0.75, and was negatively correlated (rÿ0.92,p<0.01) with alkaloid content of subspecies, but not with chemical composition or ruminal degradability of nutrients. Alkaloid content of subspecies could explain the erratic intake of tagasaste.
#2000 Elsevier Science B.V. All rights reserved.
Keywords: Chamaecytisus proliferus; Shrubs; Alkaloids; Intake
1. Introduction
Chamaecytisus proliferusforms a taxonomic complex which are shrub legume forages endemic in the Canary island. These have been introduced in many arid zones because of its deep rooting system and its nutritive value. However, this forage contains alkaloids (Muzquiz et al., 1996), mainly sparteine, which is known to have an extremely bitter taste and reduce feed intake (Hill and Pastuszewska, 1993). The aim of this study was to
Animal Feed Science and Technology 85 (2000) 279±282
*Corresponding author. Tel.:34-928451099; fax:34-928451142.
E-mail address: castanon@cicei.ulpgc.es (J.I.R. Castanon)
investigate the in¯uence of alkaloids on ruminal degradability and intake of subspecies of C. proliferus.
2. Materials and methods
Four subspecies of C. proliferus used in this research were: palmesis, canariae, meridionalisand calderae. Thin stems (<3 mm diameter) with their leaves were taken from shrubs of each subspecies in spring and autumn.
Samples were weighed, cut and dried at 608C to about 90% dry matter. Then they were ground to pass a 0.5 mm screen prior to chemical analysis, and through a 2 mm screen for in sacco trials. Fresh samples containing 300±400 g DM kgÿ1
were offered to adult goats to determine the intake of each subspecies.
Organic matter and crude protein content of samples were determined according to Association of Of®cial Analytical Chemists (1990). Neutral detergent ®ber was analysed according to Van Soest et al. (1991). Alkaloid content of shrubs was evaluated by GLC after extraction with dichloromethane (Muzquiz et al., 1996).
Six female goats weighing 556.3 kg were used for the intake measurement. Two goats were housed in each of three pens. About 3 kg of each subspecies and ofMedicago arboreawere daily offered, each shrub in a different feeder (®ve feeders in each pen). Goats were allowed to consume the shrubs during 5 days in each season, and daily intake of each subspecies in each pen was recorded. Mean daily intake of each subspecies in each pen was used for calculations.
Three adult male Canarian goats ®tted with permanent rumen cannulae were used to measure ruminal degradability of organic matter and nitrogen of shrubs with the in sacco technique (Mehrez and Orskov, 1977). Animals were fed on a mixture ofC. proliferus subspecies ad libitum and 200 g whole maize grain (100 g twice daily) during the entire experimental period. About 3 g of sample was weighed into 10 cm15 cm nylon bags of 50mm porosity and closed by heat sealing. Duplicate bags were incubated in the rumen of each animal for 4, 8, 16, 24, 48 and 72 h. After removal, they were washed and dried to a constant weight at 608C in a forced-air oven. The effective organic matter and nitrogen degradability were calculated according to Orskov and McDonald (1979), using 0.045 hÿ1as the theoretical passage rate.
Chemical composition, intake and in sacco degradability of each subspecies were compared by LSD tests, using the general linear models procedure (Statistical Analysis Systems Institute, 1989), and a level ofp<0.05 was chosen as the minimum for statistical signi®cance. Correlation analyses were done among chemical composition, degradability and intake of shrubs.
3. Results and discussion
Total alkaloid content of subspecies varied from 1.6 to 11.3 g kgÿ1
DM, with sparteine accounting for more than 80% of total alkaloids (Table 1). Spring cuts had higher alkaloids content than autumn cuts, which could explain that grazing sheep on
containing forages performed worse in spring than in autumn (Seaman, 1987). While some authors (Seaman, 1987; McKenzie et al., 1988) have reported that alkaloids can induce gastro-enteritis and mortality in ruminants, Borens and Poppi (1990) observed no ill health in animals consuming tagasaste for periods of up to 9 months.
Ruminal effective organic matter degradability of subspecies ranged between 42 and 54%, and effective nitrogen degradability between 52 and 71%. These values are within the range reported by other authors (Varvikko and Khalili, 1993; Bonsi et al., 1995; Umunna et al., 1995a). Alkaloid content did not correlate (p>0.05) with ruminal effective organic matter or nitrogen degradability, which suggests that alkaloids did not affect the activity of ruminal micro-organisms.
Total dry matter intake of shrubs was low (35.9 and 44.5 g kgÿ1BW0.75for spring and autumn cut, respectively). Intake of palmensis and canariae was the highest, and of meridionalisthe lowest. Intake did not correlated (p>0.05) with organic matter, crude protein or neutral detergent ®bre content or rumen effective degradability of organic matter and nitrogen, but intake negatively correlated with alkaloid content (rÿ0.92, p<0.01, n24) or sparteine content (rÿ0.94, p<0.01, n24) of tagasaste subspecies, and therefore alkaloid content of the tagasaste subspecies could explain the erratic intake of tagasaste reported by some authors (Varvikko and Khalili, 1993; Umunna et al., 1995b; Kaitho et al., 1997), or the low performance of animals fed on tagasaste (Borens and Poppi, 1990).
Table 1
Chemical composition (g kgÿ1DM), alkaloid content (g kgÿ1DM), effective organic matter (OM) and nitrogen (N) degradability (%), and daily feed intake (g DM kgÿ1BW0.75) of subspecies ofChamaecytisus proliferusa
Subspecies OM CP NDF Sparteine Total alkaloids
aMeans with different superscripts in the same column differ atp<0.05. bN: number of observations.
cS.E.M.: standard error of the mean.
The results of this study suggest that the nutritive value of tagasaste subspecies could be limited by their alkaloid content, which reduces intake, particularly in spring. If possible, low alkaloid subspecies should be chosen to achieve the highest intake.
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