Production performance
The effects of feeding diets containing
Hydrilla verticillata at different levels on production performance of Thai native chicken is shown in Table 4.
Feed intake
The results explained that feed intake (FI) did not differ (P>0.05) among the four groups of the Thai native chickens fed
Hydrilla verticillata. Nevertheless, there was a tendency for higher FI to be associated with the intensity of
Hydrilla verticillata. This observation was also identified by
Rodjan (2011) that there was a significant effect of feeding combinations of
Hydrilla verticillata and rubber seed kernel (RSK) for fattening swine weighing 20-60 kg on FI where by FI increased with the increase in the levels of
Hydrilla verticillata at 0%, 10%, 15% and 20% in the diet accounting for 93.98, 96.56, 101.65 and 104.39 kg, respectively. This
Hydrilla verticillata contains high fiber which affects adversely in digestive system due to fiber would absorb water in digestive track then make feed intake flow through digestive tract faster.
(Muzi et al., 2017 and
Hussein et al., 2021) report that fiber addition in diets could cause the reduction of digestibility, consequently resulted insufficient energy in chicken and force chicken eat more feed to receive adequate energy for growing.
Body weight gain
The results obtained revealed that feeding
Hydrilla verticillata to the chickens aged 1-4, 5-8 and 9-12 weeks old had no significant effect (P>0.05) on body weight gain (BWG). However, it was inclined that inverse variation existed between the increase of
Hydrilla verticillata and the decrease of WG. The 1-12 weeks old group fed with 15%
Hydrilla verticillata noticeably had the least WG (P<0.05). In agreement with
Rodjan (2011), it was reported that swine weighing 60-90 kg had BWG minimization at 30.00, 29.50, 30.31 and 29.69 kg, respectively, when given 0%, 10%, 15% and 20%
Hydrilla verticillata mixed with rubber seed kernel (RSK). The finding could have resulted from a typically high fiber and ash content of
Hydrilla verticillate which consequently, could hinder feed digestibility and efficiency of absorption once passed through GIT and caused nutrient deficiency in feed
(Muzter et al., 1977 and
Hussein et al., 2021). Owing to the fiber caused feed intake run through digestive track faster meanwhile ash content envelops cell of feed component which later degenerate the feed assimilation efficiency
(Muzi et al., 2017; Ohanaka et al., 2018). From this reason, weight gain of the chicken in this treatment was lower than the control group.
Feed conversion ratio
The results disclosed that the diet containing
Hydrilla verticillata had an influence (P<0.05) on feed conversion ratio on the 1-4 week old chickens. The chickens provided with 0%
Hydrilla verticillata showed best in FCR (P<0.05). Nonetheless, no apparent FCR was observed in the three treatment groups including 5-8, 9-12 and 1-12 weeks old (P>0.05). Incomplete gastro intestinal tract development affected different FCR occurring in the starter scheme -4 weeks old), causing limited digestibility and efficiency of feed utilization
(Kanto, 1986). Moreover, high levels of fiber (8.15%) and ash (28.05%) contents found in
Hydrilla verticillata, leading to inefficient feed digestibility and absorption resulting in reduced feed utilization. According to
Onwedike (1986), when protein-digesting enzyme was deterred by fiber-enriched feed, protein and amino acids utilization would be decreased. There was also an effect of 1 per cent of the fibers in feed on less protein digestibility, accounting for 1.1-1.6%
(Siriwathananukul, 1989). Thus, a negative impact on FCR was due to the substances in
Hydrilla verticillata that featured high fiber and ash contents, yet low nitrogen-free extract contents.
Carcass characteristics
Carcass characteristics of Thai native chicken fed diets containing different levels of
Hydrilla verticillata is shown in Table 5. There were significant differences in carcass characteristics of chickens foddered with 0%, 5%, 10% and 15%
Hydrilla verticillata. That is, the live weight (LW) was variant when a 24-hour fasting period was applied before slaughter (P>0.05). Since each group treated with
Hydrilla verticillate had different weights at the final experiment (P<0.05), different weights were shown (P<0.05). No significant differences (P>0.05) were found in the hot carcass percentage, pectoralis majors, pectoralis minors, breasts, thighs, drumsticks, wings and total edible carcass (P>0.05) when dissected for carcass characteristics study. The gizzard weight (GW) was, however, statistically different (P<0.05). The increase in the levels of
Hydrilla verticillata resulted in greater gizzard weight (GW), as
Hydrilla verticillata could accelerate the activation of chicken gizzard, causing relatively heavier body weight because of the gizzard’s size.
Reported by Kubena et al. (1974), in comparison with the utilization of the feed with less fiber contents, the consumption supplemented with high fiber contents led to larger sized gizzards. No differences (P>0.05) existed in the sampling chickens in terms of abdominal fat, possibly because L-lysine and methionine were applied in high concentrations. In conformity with the report by
Kuprasert (1995), it was determined that higher methionine intake could reduce more body fat accumulation. Restricted feed digestibility and absorption could be predicted as a consequence of a considerable amount of high-fiber feed intake, causing low metabolism
(Hussein et al., 2021). Therefore, most energy was allocated to sustain living, leaving insufficient energy to be converted into visceral fat.
Cost economics
The results revealed that the finisher period (9-12 weeks) Thai native chickens foddered with 5%
Hydrilla verticillata was lowest in production costs (38.33 Baht/kg); the other groups fed with 10% and 15%
Hydrilla verticillata were presented accordingly at 38.61 and 38.61 Baht/kg. Surprisingly, the control had the highest production costs of 38.71 Baht/kg, because at the finisher period, the price of feed was higher than in other groups as shown in Table 6.
