Effects of Tribulus terrestris ( Puncture Vine ) Supplementation on Performance and Digestive System of Broiler Chicks

The purpose of this study was to determine the possible effects of the herbal preparation Tribulus terrestris (TT) extract on muscle building (increase in breast and legs weight) in broiler chicks. One hundred eighty broiler chicks were assigned to three treatment groups; control, 180 ppm TT and 360 ppm TT extract. Body weight, body gain and dietary intake were determined weekly for 6 weeks. Control diet included 234 g crude protein (CP) and 3141 kcal ME (grower) per kg diet during 1-21 days of age and 204 g CP with 3199 kcal ME (finisher) per kg diet for 22-42 days of age. Growth performance, muscle building (increase in breast and legs weights) and digestive system parts were determined. TT extract did not affect growth performance and muscle building but decreased ileum + jejunum and empty gut weights (P<0.05). In conclusion, the present results showed that Tribulus terrestris had no effect on growth or muscle building. This may be TT extract do not work in birds as do in human subjects, and more likely, the physiological differences between human and bird.


Giriş
Tribulus terrestris (TT) is an industrial source for production of medicinal preparations based on its saponin fraction.Food supplements with a claim of general stimulating action are also currently on sale in Europe and USA (Kostova & Dinchev 2005).
Tribulus terrestris L. (Zygophyllaceae), usually called "demir dikeni" in Turkey, is an annual herb that is widely distributed in Turkey, China, Japan, Korea, the western part of Asia, the southern part of Europe and Africa.It is popularly claimed to improve sexual function possibly through increase in the free serum testosterone (Brown et al 2001).This plant is extremely rich in substances having potential biological significance such as saponins, flavonoids, alkaloids (Wang et al 1997;Sun et al 2002), glycosides, phytosteroids (Wu et al 1996) and other constituents (Wu et al 1999).Although the furostanol saponins (Combarieu et al 2003;Conrad et al 2004) are the main components of TT of Bulgarian origin, only methylprotodioscin, protodioscin, methylprototribestin and prototribestin have been isolated and identified so far (Kostova et al 2002).
In humans, it has been used to increase testosterone levels and improve muscle (Adimoelja & Adaikan 1997;Gauthaman et al 2002;Adaikan et al 2000).Protodioscin, the most dominant saponin in TT, is the main substance responsible for increasing testosterone (Ganzera et al 2001) and its derivatives (Adimoelja & Adaikan 1997;Gauthaman et al 2000).Protodioscin has, also, been found to increase the levels of dehydroepiandrosterone (Adimoelja & Adaikan 1997), dihydrotestosterone and dehydroepiandrosterone sulphate (Gauthaman et al 2000).Gauthaman & Adaikan (2008) investigated the hormonal effects of TT in rabbit and rat.Rabbits and normal rats were treated with 2.5, 5 and 10 mg kg -1 of TT extract orally for 8 weeks, for their chronic study.In addition, castrated rats were treated either with testosterone cypionate (10 mg kg -1 , subcutaneously; biweekly for 8 weeks) or TT orally (5 mg kg daily -1 for 8 weeks).In rabbits, both testosterone and dihydrotestosterone were increased compared to control, however, only the increases in dihydrotestosterone (by 30and 32% at 5 and 10 mg kg -1 ) were statistically significant.In castrated rats, increases in testosterone levels by 51% and 25% were observed with testosterone cypionate and TT extract respectively that were statistically significant.TT increases some of the sex hormones, possibly due to the presence of protodioscin in the extract.The testosterone precursors enhance testosterone production because they are one small biochemical step away from testosterone and help elevate testosterone through anabolic steroid effects.TT has an effect on even females.Geyer et al (2000) detected the anabolic-androgenic steroids 4-androstene-3,17-dion, 4-androstene-3ß,17ß-diol, 5-androstene-3ß,17ß-diol, 19-nor-4-androstene-3,17-dion and 19-nor-4-androstene-3ß,17ß-diol in TT extract and found out that the urinary concentrations of norandrosterone was between 4 and 623 ng ml -1 by 3-4 hours after administration of TT.A female volunteer additionally showed an increase in the ratio testosterone/epitestosterone from 0.6 to 4.2.
The active agent in TT is believed to be protodioscin.Protodioscin is a precursor to dehydroepiandrosterone (DHEA).As you may know, DHEA and androstenedione are precursors to testosterone.As one ages, androgen levels decline.Therefore, DHEA and androstenedione supplementation have been theorized as a means of naturally increasing testoserone levels particularly in older individuals.Although TT is a precursor to DHEA, TT is believed to indirectly affect testosterone levels by stimulating the release of leutinizing hormone (LH).LH serves to stimulate the natural production of testosterone.Theoretically, moderately increasing testosterone availability during training may promote greater gains in strength and muscle mass (Kreider 2001).

Sahin
& Forbes (1997) studied dehydroepiandrosterone in broiler chicks to alleviate the effect of corticosterone administration and found out that dehydroepiandrosterone tended to increase muscle mass in broiler chicks.Çek et al (2007) examined the effects of TT on growth acceleration in the Convict Cichlid Cichlasoma nigrofasciatum.A 0.30 g TT extract in one l water significantly improved the growth rate of C. nigrofasciatum.
T a r ı m B i l i m l e r i D e r g i s i -J o u r n a l o f A g r i c u l t u r a l S c i e n c e s 16 (2010) 271-277

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However, there is a limited study whether TT extract affects growth rate and body muscle (increase in breast and legs weight) in broiler chicks since these body parts are of significant economical importance on broiler meat production.More recently, Duru (2005) used TT extract (60 and 120 ppm) by giving broiler chicks orally in commercial diet for 21 days.TT extract did not affect growth performance and body parts.This result encouraged us to test the efficacy of TT extract in higher doses (180 and 360 ppm in basal diets) on growth and muscle building in broiler chicks.

Material and Methods
At the beginning of experiment, one-day old 180 broiler chicks (Ross 308) were individually weighed and allocated into experimental groups of equal body weight (51.5± 4.16 g, one day after chicks arrived to experimental unit from hatchery) according to the following experimental design for 42 days.Experimental birds were equally divided into three treatment groups; 60 birds (27 ♀, 33 ♂) were control (0 ppm Tribulus terrestris extract, TT), 60 birds (36 ♀, 24 ♂) were given 180 ppm TT extract and 60 birds (28 ♀, 32 ♂) were 360 ppm TT extract in their diet.Treatment birds were divided into three sub-groups to make replication groups each included 20 birds.TT extract (origin: bulgarian) were purchased from Gym Spor Sağlık & Gıda San.Tic. Ltd.Şti. in Istanbul.Powder of TT extract in commercial capsule poured and mixed carefully into basal diet.Experimental diets were mainly based on corn and soya bean.Control diet included 234 g CP and 3141 kcal ME (grower) per kg diet for 1-21 days of age and 204 g CP with 3199 kcal ME (finisher) per kg diet for 22-42 days of age (Table 1).Both control and treatment diets did not include any antibiotics.Water was available throughout the experimental period.The experimental chicks were kept in floor pens (1.4 m × 1.4 m) in a poultry room with continuous 24 h day light and 18-24°C (a gradual decrease from 33°C from day old age) ambient temperature.The growth of chicks was monitored by weighing on weekly basis.Feed conversion ratio (g feed: g gain) were calculated for each replication during the experimental period.At the end of experiment when experimental birds were 42-d old, they (5 ♀ and 5 ♂ for each treatment) were slaughtered humanly for determination of body components and digestive system parts.
Data concerning growth performance, body components and digestive parts were analysed using the GLM procedure of SPSS (Windows version of SPSS, release 10.01) with Duncan's Multiple Range Test used to identify the significant differences between the respective means.Results are presented as means per bird with standard error of means (SEM).

Results and Discussion
The results regarding growth performance, body components and digestive system of broiler chicks are given in Table 2, 3 & 4, respectively.TT extract did not affect feed intake, daily gain and feed efficiency during experimental period.
According to Table 3, breast, legs, feather, heart and abdominal fat pad weights were not affected by TT treatment although males had heavier body components than females.Also, liver weight was decreased by 360 ppm TT treatment (P=0.05) in both male and female chicks.
According to Table 4, intestine (duodenum, ileum + jejunum) weight was decreased by TT extract (P<0.05) and this reflected to a decrease in empty gut weight (P<0.05).In generally, TT extract decreased digestive morphology even though some parts (crop, proventriculus, gizzard, pancreas, ceca and colon) were not affected significantly.
It was expected in the current study that TT extract may increase blood testosterone level and, consequently, increase growth rate with the weights of body parts such as but this was not happen.In contrast, Gauthaman et al (2002) found out that the TT extract increased testosterone levels in rats.Çek et al (2007) found that the growth rate of fish treated with TT was found to be faster than that of the controls.The effects of the TT extract on body weight have been studied by Dimitrov et al (1987) in immature sheep and by Gauthaman et al (2002) in rats.Both authors found an increase in body weight, sexual activity and spermatogenesis.However, the present results in broiler chicks are  In the present study, TT extract in mash form were used and administrated orally in food.When ingested, TT might have been solved in digestive system since it is soluble in water (Pandian & Sheela 1995).Before being absorbed, testosteronic compounds, more likely, diminished by bird's digestive system in current dietary supplementation.
The present finding regarding digestive organ weights showed that TT decreased intestine weight significantly.It may have caused poor feed efficiency in treatment birds, but this was not happened.Despite of having shorter digestive system, TT birds utilised food efficiently as much

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as control birds did.This might be a result of increased digestive enzymes or changed hormonal status of treatment birds due to the chemical content of TT.Also, the decreasing effect of TT on intestine weight can be attributed to (1) TT might have decreased lipid accretion and (2) decreased the injuries of epithelial tissue of intestine since Sati et al (2009) found out that TT extract decreased injuries in aorta endothelial and blood lipid levels in rabbit.

Conclusion
The present study showed that Tribulus terrestris had no effect on growth or muscle building, suggesting that TT extract do not work in birds as do in human subjects, more likely, due to the physiological difference between human and animal species.

Table 2 -Effects of Tribulus terrestris (TT) extract on body weight feed intake and feed conversion ratio (FCR) of broiler chicks
Tribulus terrestris extract, 180TT: 180 ppm Tribulus terrestris extract, 360TT:360 ppm Tribulus terrestris extract not similar to the previous findings in different species.Method of extraction may play an important role in testosteronic effects of TT.

Table 3 -Effects of Tribulus terrestris (TT) extract on body components of broiler chicks
a,b,c with no common superscript show the significant differences between treatments in female chicks.A,B,C with no common superscript show the significant difference between treatments in male chicks.Control: no Tribulus terrestris extract, 180TT: 180 ppm Tribulus terrestris extract, 360TT:360 ppm Tribulus terrestris extract.Percentage data were obtained according to slaughter weights.

Table 4 -Effects of Tribulus terrestris (TT) extract on digestive parts of broiler chicks
,b,c with no common superscript show the significant differences between treatments in chicks Control: no Tribulus terrestris extract, 180TT: 180 ppm Tribulus terrestris extract, 360TT:360 ppm Tribulus terrestris extract.Percentage data were obtained according to slaughter weights.