Effect of garlic on the productive variables of chickens
In this study, the potential effect of the diet with concentrate supplemented with different doses of purple garlic on the growth promotion and intestinal morphometry of female and male Cobb Vantress 500 broilers were evaluated. Broilers supplemented for 40 days with 0.2% and 0.3% of garlic reached a weight significative at the end of this period, a weight significative (P<0.05) more significant than that achieved with the other groups, however, there was no significant difference in feed conversion among four groups. The effect of feeding different levels of purple garlic powder on the performance of broilers is shown in Table 1. The productive parameters did not differ significantly (P<0.05) among four groups in females. However, the BWG and TP in the T
2 and T
3 groups in males were considerably higher than the other groups. At the numerical level, the productive parameters: ADG and FCR were better in the T
2 and T
3 groups than in the other groups (Table 1).
According to what has been published, the effect of garlic on the productive variables of chickens is variable:
Choi et al., (2010), who administered to poultry for 35 days, with 1%, 3%, 5% garlic powder, did not find a significant effect on productive parameters; instead,
Javandel et al., (2008) used diets supplemented with garlic flour and only in the highest dose (2%), they observe an increase in feed conversion. With such small amounts of 0.2% and 0.3% of purple garlic, the present study achieved the goal of achieving a higher weight than the groups that did not receive a garlic supplement. In the works of
Puvaca et al., (2014), garlic improved the feed conversion rate with 0.5% garlic powder in the diet of broiler chicken. With a dose of 5% garlic,
Al-Shuwaili et al., (2015) reported improved live bird weight and feed conversion when administered for eight weeks. On the other hand,
Karangiya et al., (2016) concluded that a 1% dose of garlic works as a growth promoter in chickens. With a lower amount of purple garlic from ²Las Pedroñeras², the present work achieved this objective, so a low-medium dose was able to improve the productive variables.
The female bird´s body weight
Did not differ significantly on any recorded day. However, the body weight in the males of the T2 and T3 groups was significantly higher (P<0.05) on day 40 compared to the other groups (Table 2).
The body weight in the male broilers
Was significantly lower (P<0.05) in the control and T1 groups than in other groups and the female groups. Chicken genders have been documented to affect glycan and lipid metabolism, related to growth performance and different-sex hormones generally influence metabolic processes
(Varlamov et al., 2015). In chickens, like other species, there is an effect of sex on the growth rate; absolute sexual dimorphism is reached in chickens at 14 days of age, from which point its value increases in the males. In this early growth stage, corresponding to the pre-inflection phase of the growth curve, bodyweight shows an exponentially increasing pattern. Male and female broilers have different initial growth potentials; for example, males use food more efficiently than females, from week 5 to 8. This explains why the males reached greater weight at day 40 than the females in groups T
2 and T
3 not so in groups T
0 that before day 40 the males showed a greater weight than the females, however at day 40, they were 6% less heavy than females. In the T1 group from day 2 to 40, the females were heavier than the males.
The available information shows that garlic can improve production parameters. However, according to the available literature, the different results obtained with the administration of garlic could be due to a difference in the administered dose, the ecotype of the garlic, the sex of the chicken.
Gut morphometry
The statistical analysis of the morphometry of the duodenum showed that values of mean villi height were significantly (P<0.05) lower in T
1 and T
2 compared with other groups. The values of duodenum mean villi width were no differences between the groups. The jejunum values of mean villi height in T1 were lower than the other groups, the mean T3 group values were significantly (P<0.05) lower than the T
2 group. (Fig 1). Four experimental groups observed a non-significant difference was observed in the total intestine, duodenum, jejunum and ileum lengths among four experimental groups (Fig 2).
Duodenum is the first part of the small intestine where 95% of the fat is digested; in the jejunum, the major nutrients are digested and absorbed (
Svihus, 2014). In the current study, the statistical analysis of the morphometry showed that the values of the mean height of the villi of the duodenum were significantly (P<0.05) lower in T1 and T2 than in the other groups. Furthermore, the jejunum values of the mean height of the villi in T1 were lower than in the other groups; the mean jejunal villus width values in all treatment groups were significantly (P<0.05) lower than in the control group. Therefore, villi height and width have been positively related to increased nutrient uptake
(Oladele et al., 2012) or compensatory mechanism. The morphometry of the villi is reported to change during chick development and the greatest dimension of the villi is observed at 20-22 days
(Arce et al., 2008). Unfortunately, in the present study, it was impossible to sample the chickens at this stage and could it be done until the end of the study (40 days) and only carried out in female birds. The present work supports the use of purple garlic from Las Pedroñeras, Spain (standardized commercial product) supplemented in the feed of broilers in a daily concentration of 0.2-0.3% as a natural alternative and viable tool in broilers for growth promotion.
The type and presentation of the garlic used may be related to the results obtained. A standardized commercial product of 65% Spanish purple garlic powder was used in the present study. In other studies, garlic bulbs purchased from the local market have been used or supplements. It is recognized that different garlic ecotypes and variations in processing could alter the chemical form of the biologically active components
(Dubey et al., 2010; Singh, et al., 2014; Singh, 2015). The garlic ecotype ²Morado de Las Pedroñeras² showed numerous differences with black garlic in the volatile profile, ascorbic acid content, sugar and polyphenols, antioxidant capacity and composition of phenolic acids and flavonoids (
Martínez-Casas et al., 2017). In addition, the highly unstable thiosulfinates, such as allicin (considered responsible for most of the pharmacological activity of crushed raw garlic cloves), disappear during processing and are quickly transformed into various organosulfur components (
Lawson and Hunsaker, 2018).
As mentioned previously, a factor that potentially influences garlic’s growth performance is gender
(Javandel et al., 2008). However, garlic’s exact mechanism of action as a growth promotor is uncertain.