The livestock industry, and particularly the poultry industry, has been faced with a drop in productivity due to the ban on antibiotics as growth promoters in animal nutrition [1]. The use of antibiotics as growth promoters has led not only to the development of resistance in pathogenic microbes [2][3], but also to health problems linked to the antibiotic residues in livestock products intended for human consumption [3]. This ban has led to a search for natural biodegradable compounds, derived from plants called phytobiotics that can produce the same effects as antibiotics with less or no impact on animal and human health and the environment [4]. Studies revealed the presence in phytobiotics of active compounds such as isoprenes, flavonoids, tannins and alkaloids that act on animal growth through their antimicrobial and antioxidant properties [5][6]. A large number of studies involving phytobiotics have been carried out as feed additives. These include among others plant and spice [7][8], essential oils [9][10] and neem seed oil [4][11].

Cupressussempervirensisa tree that can grow up to 30 m tall, with leaves measuring 0.5 to 1 mm, dark green in colour and obtuse [12]. Native to the Mediterranean basin, it is widespread in central and northern Africa, Asia, southern Europe, North America and southern China [13]. In traditional medicine, the leaves of this tree are generally used to relieve pains such as colds, coughs, bronchitis, haemorrhoids, varicose veins, venous diseases and circulatory disorders [12]. Several studies have reported its antibacterial and antifungal [14], antiviral [15], antiparasitic and insecticidal [13][16] antioxidant [17], anti-carcinogenic [18], hypolipidaemic [19], osteogenic [20] and antimicrobial [21] properties. All these properties are based on the presence of compounds such as alkaloids, flavonoids, tannins, saponins, phenols and several other biologically active compounds [22] that can act on animal growth [21]. In view of its properties and secondary metabolites, this plant could provide health and well-being, which could positively affect animal growth performance. The general objective of this study was to evaluate the effect of incorporating an infusion of Cupressussempervirens fresh leaves as a feed additive to mitigate the effects of antibiotics growth promoters in animal nutrition.

The inclusion of large quantities of feed additives is likely to considerably reduce the feed intake in animals [26][27]. In this study, the reduction in feed intake in broilers fed on rations supplemented with 8 and 10 ml Cupressussempervirensfiltrate/Ldrinking water could be related to the bitterness of the water induced by the presence of alkaloids in the high levels of the infusion. This result is in line with previous research by [8] who reported a significant drop in feed intake with the incorporation of 5 g of Pentadiplandrabrazzeana powder/L of drinking water. These authors explain these results by the presence of alkaloids in the spice, which progressively induced a bitter taste in the drinking water that was not appreciated by the chickens, causing a drop in water intake and consequently in feed intake. It was also noted in this study that the feed intake of chickens fed on 6 ml/L of Cupressussempervirens infusion was comparable to that of the chickens given the antibiotic, which was significantly higher than that of the control group. This result contradicts the finding of [28] who repported a significant increase in feed intake with the increasing levels of methenamine in drinking water of broilers.

Live weight and weight gain at the finisher phase and over the entire study period of broilers supplemented with antibiotic and 6 ml of Cupressussempervirens filtrate were significantly high as compared to all other treatments groups. These results are in line with the findings of [29] who reported that 50 ml of ginger extract per litre of drinking water significantly improved the final live weight and weekly weight gain of broilers; and the results of [30] who reported a significantly positive effect on the weight gain of rats fed with Cupressussempervirens extaits. This beneficial effect of live weight and weight gain with this phytobiotic in drinking water was explained by the presence of phenolic, terpenoic, and alkaloid compounds that are also present in Cupressussempervirens.

Table6. Effects of increasing rate of Cupressussempervirens infusion in water on biochemical parameters of broilers.

^a,b,c,dmeans bearing the same letter on the same line are not significantly different (P > 0.05). T0: control ration with no additives; T0+: ration with no additive control + 1 g/L doxycycline; P: P-value.

Table 7. Variation of broilers intestinal microbial count as affected by the infusion of fresh leaves of Cupressussempervirens rate in drinking water.

^a,b,c,dmeans bearing the same letter on the same line are not significantly different (P > 0.05). T0: control ration with no additives; T0+: ration with no additive control + 1 g/L doxycycline; P: P-value.

These active compounds can reduce host microbial competition for nutrients by reducing pathogenic bacteria. The improvement in live weight and weight gain in broilers fed on antibiotic supplemented feed could be explained by its ability to modulate the microbiota by reducing pathogenic bacteria (Escherichiacoli and Salmonella).

The feed conversion ratio (FCR) at the finisher phase and over the entire trial period was significantly higher than that of chickens supplemented with antibiotics. This result is in agreement with the work of [28] who reported that the feed conversion ratio of broilers on the additive-free ration was significantly higher than that of the positive control batch, but remained comparable to rations fed methenamine in the drinking water. These results contradict those of [7] and [31] who reported a decrease in feed conversion in broilers and quail with the inclusion of 0.2%, 0.4%, and 0.6% of Dichostachysglomerata powder in the feed.

Increasing rates of Cupressussempervirens infusion in broiler drinking water, had no significant effect on carcass characteristics and relative weights of organs. This result is in agreement with the results of [32], who recorded no significant effect on carcass yield, gut weight, the relative weight of liver, gizzard, the pancreas of broilers fed Livol (1 ml/2litre water), Livotal (1 ml/4litre water) and hepato promotor (1 ml/4litre water) which are commercial phytobiotics. Similarly, [28] reported that the increasing levels of methenamine in the drinking water of broilers had no significant effect on carcass yield and relative organ weights compared with chickens from control batches. In the same line, [8] found that the inclusion of increasing rates of Pentadiplandrabrazzeana powder in the drinking water of broilers significantly affected carcass yield, but not digestive organs. Increasing levels of Cupressussempervirens filtrate in the drinking water had no significant effect on abdominal fat. This result corroborates those of [31] who reported that supplementing Japanese quails with gradual levels of Dichostachysglomerata fruit powder indicated no significant effect on relative abdominal fat weight. In contrast, [33] reported that the incorporation of 1.5 g/kg of Capsicumannumintothebroiler ration resulted in a 43.4% reduction in abdominal fat compared with the control ration.

Blood parameters reflect the health status of an organism and any changes in these could indicate a dietary imbalance or microbial attack [8][34] and animals with good blood composition are likely to perform well [35]. In the present study, red blood cell count, mean corpuscular haemoglobin content and platelet counts were not significantly affected by the phytobiotic. The white blood cells of the broilers in the control group without the additive were significantly higher than those of broilers supplemented with antibiotic, while the Hgb, VGM, CCMH and PLT of the chickens in the control ration were significantly lower with Cupressussempervirens infusion. This is different from the finding of [29] which revealed an increase in red blood cell count in broilers receiving ginger extracts, and that of [36] which showed no significant effect on white blood cell count when 0.25% garlic, ginger and the garlic-ginger mixture were incorporated into the broiler feed. The present result corroborates that of [37] who stated that in broilers the haemoglobin level increased with aqueous garlic extracts (20 ml/L) in the drinking water. The present result is different from the findings of [38] who recorded no significant effects on haemoglobin levels in chickens fed different rates of garlic.

Supplementing broilers with increasing levels of Cupressussempervirens had no significant effect on ASAT and ALAT concentrations. This result suggests that the active principles present in this plant have no harmful effect on the liver. This result corroborates the work of [39] who reported that ginger and garlic essential oils administered by gavage at doses of 10, 20 and 40 mg/kg/day had no effect on serum transaminase activity (ALAT and ASAT). This observation contradicts the results of [40] who reported that the addition of 5% ginger, garlic and cinnamon to the turkey ration reduced the concentration of ALAT and ASAT. Serum urea is an index that reflects the status of protein metabolism, renal function and body nutrition. Serum urea and creatinine concentrations were not significantly affected by increasing levels of Cupressussempervirens in drinking water. This result is in agreement with that of [36] who reported that the addition of 0.25% ginger, garlic and the ginger-garlic mixture to the broiler ration did not significantly affect creatinine and urea concentrations. Feeding chickens with increasing levels of infusion of this plant through the drinking water did not significantly affect the serum cholesterol profile. This result contradicts the work of [19] who reported that the addition of thyme to the broilers’ ration induced a significant drop in serum levels of HDL, total cholesterol and total lipids.

The increasing levels of Cupressussempervirens in the broiler drinking water induced a significant increase in the Lactobacilli count compared to the negative control ration. The number of Escherichiacoli decreased significantly with the increasing levels of Cupressussempervirens filtrate in drinking water compared to the negative control ration, while the Salmonella load of the control ration was comparable with the other treatments. [41] reported that when conditions in the intestinal environment become favourable, lactic acid bacteria multiply and selectively eliminate pathogenic bacteria (Salmonella and Escherichiacoli) due to their acidifying properties and their ability to produce antibacterial substances such as organic acids. The hydrophobic compounds present in plants that penetrate the bacterial cell membrane disintegrate the membrane structure and cause leaks, making the microbes less virulent. Contrary to the present result, [42] reported a significant increase in the number of Salmonella, unlike the number of Escherichiacoli, which was not affected by the supplementation of silver nanoparticles in the drinking water of broilers. Birds supplemented with 10 ml of Cupressussempervirens recorded the lowest Salmonella and Escherichiacoli loads. This suggests that, at this dose, the concentration of active compounds present in this phytobiotic has a positive effect on the inhibition of pathogenic bacteria.

Incorporating 6 ml of Cupressussempervirens infusion per litre of drinking water can be used as a substitute for antibiotics to modulate the intestinal microbiota and improve nutrient absorption, with a positive impact on the growth performance of broiler chickens, without any toxic effect on vital organs such as the liver and kidneys.