ELSEVIER Small Ruminant Research 21 (1996) 195-201
Goats fed tannin-containing leaves do not exhibit toxic syndromes
N. Silanikove *, N. Gilboa, A. Perevolotsky, Z. Nitsan Agricultural Research Organization (ARO), The Volcani Center, P.O. Box 6, Bet Dagan 50 250, Israel
Accepted 30 November 1995
The blood metabolic profile was examined in 2-3 year old non-lactating and non-pregnant Mamber goats consuming Quercus calliprinos (oak), Pistacia lentiscus (pistacia) and Cerafonia siliqua (carob) leaves to determine whether intake of tannin-rich fodder induces subclinical systemic toxicity. Total phenolic and condensed tannin content ranked in the order pistacia > oak > carob. Goats ...view middle of the document...
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lished (Robbins et al., 1987; Silanikove et al., 1994; Silanikove et al., 1996). Reduced palatability, low rate of evacuation of digesta out of the rumen and toxic effects are factors that were considered in the explanation of the negative effects of tannins on feed intake in ruminants (Kumar and Singh, 1984; Provenza, 1995). Toxic effects have been described as the most important factor (Bryant et al., 1991) and are reflected by a damage in the liver, kidneys and the epithelium of the digestive tract (Kumar and Singh, 1984; Reed, 1995).
Goats are predominantly browsers, and on Mediterranean scrubland, browse constitutes 60-80% of goat diets (Kababya, 1995). Goats are able to consume larger amounts of tannin-rich browse than sheep under similar conditions (Gilboa et al., 1995;
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196 N. Silanikoue et al./Small Ruminant Research 21 (1996) 195-201
Silanikove et al., 1996) which may increase the risk of exposing goats to subclinical systemic toxicity.
In the present experiment, the blood metabolic profile was examined in 2- to 3-year-old non-lactat- ing and non-pregnant Mamber goats consuming Quercus calliprinos (Common oak), Pistacia lentis- cus (pistacia) and Ceratonia siliqua (carob) leaves to determine whether intake of tannin-rich fodder in- duces subclinical systemic toxicity. Subclinical sys- temic toxicity was evaluated by applying a wide- range metabolic profile test (Silanikove and Tiomkin, 1992).
2. Materials and methods
The experiments were carried out each time with four non-lactating and non-pregnant 2-3 year old female Mamber goats (a breed indigenous to the Mediterranean woodland) weighing 35 (SD + 5) kg, chosen from a stock of eight goats. The animals were stall-fed individually in a protected yard and equipped with troughs which enabled quantitative measure- ment of feed intake.
Evergreen leaves attached to small branches (2-3 mm in diameter) of Common oak, carob and pistacia were harvested by clippers once a week early in the morning and stored at - 20°C. The daily allotment was removed from the freezer, let to thaw for at least 3 h, and fed once daily ad libitum at 08:OO. Water was always available.
2.3. Experimental procedures
The animals were adapted for 2 weeks to con- sume the experimental diet as their sole feed by gradually replacing their previous diet (wheat hay ad libitum + 100 g concentrates per day) with that consisting of one of the experimental leaves. The animals were fed oak, pistacia, or carob solely for 2 weeks before the commencement of blood sampling. Blood (10 ml) was taken from each goat from the
jugular vein by a syringe at 08:OO h during the second week, and the serum was separated and stored at -20°C. Voluntary feed intake was moni- tored at the end of the second week; body weight was determined...