Fatty acid profile of vegetable oils
The fatty acid profile of rapeseed oil and palm oil is presented in Table 4. The estimated fatty acid profile in this research work indicated rapeseed oil (per 100 g of fat) contains 10.362 g of saturated fatty acids (SFA), 45.486 g of monounsaturated fatty acids (MUFA) and 18.582 g of polyunsaturated fatty acids (PUFA). Comparatively, fatty acid composition of palm oil (per 100 g of fat) values are 22.467 g of SFA, 7.129 g of MUFA and 3.6 g of PUFA. The results indicate rapeseed oil is rich in unsaturated fatty acid (USFA) and less in SFA concentration whereas palm oil is rich in the SFA. The polyunsaturated fatty acids profile of rapeseed oil estimated by gas chromatography in this study (g/100 g fat) were 6.839 of ALA (C18:3 n-3), 0.718 of EPA (C20:5 n-3) and 0.088 of DHA (C22:6 n-3). These results are in confirmation with other findings for ALA ranged from 8.0 to 11.1 g/100 g fat
(Ghazani et al., 2013; Lindman, 2015). The analytical values given by
Eshwar (2019) i.e. 10.61 per cent SFA, 63.02 per cent MUFA and 26.37 per cent of PUFA in rapeseed oil is similar to our findings.
Shrivan et al., (2017) analyzed the fatty acid profile of rapeseed oil and palm oil and reported palm oil fatty acid (g per 100 g FAs determined) had a higher concentration of saturated and monounsaturated fatty acids.
Feed intake
In this study, feeding palm oil and rapeseed oil at different proportions did not affect mean weekly cumulative feed intake of birds among treatment groups. The feed intake of broilers have been presented in Table 5. The experimental rations prepared with different oils with different fatty acid profile did not affect the energy content of the feed when it was digested and resulted in similar feed intake in all experimental birds and this is in line with observations made by
Poorghasemi et al., (2013) who fed three different vegetable oil sources (canola oil, palm oil, and sunflower oil) at 4 per cent level and their combinations. The research findings with different oils like rapeseed oil, sunflower oil, soyabean oil and palm oil and their combinations at 5 per cent
(Ghasemi et al., 2015); 6 per cent
(Khatun et al., 2016 and
Baighi et al., 2017) did not affect the feed intake during grower and finisher periods in broilers. In contrast to the present findings,
Ebdi et al., (2016) reported that addition of canola oil at 6 per cent level in broilers showed significantly higher feed intake. Simiarly,
Lopez-Ferrer et al., (1999); Coetzee and Hoffman (2002) and
Nobakht et al., (2012) also reported that dietary fat source has influence on the feed intake of broiler birds.
Weight gain
Weight gain of broilers is presented in Table 6. In the present study, body weight gain at 6
th week was significantly higher in G
3 group (2249.1g) and G
4 (2276.36g) compared to other groups. The supplementation of canola oil with tallow replacing palm oil showed significantly higher better body weight gain in broilers (
Nobakht et al., 2012). Similarly,
Khatun et al., (2016) reported addition of sunflower oil at 6 per cent level showed higher body weight gain compared to palm oil, at 6 per cent level from 3
rd week of feeding. In our study also, similar pattern of weight gain was recorded.
Ebdi et al., (2016) reported higher body weight and weekly weight gain when canola oil was added at six per cent in broiler ration compared to 3 per cent level. In contrary.
Ghasemi et al., (2015), Madhu et al., (2016) and
Abdulla et al., (2017) compared inclusion of canola oil, palm oil, soya bean oil, and linseed oil in broiler ration at 6 per cent levels and reported that there was no influence on body weight gain in broilers. It was clarified that, dietary fatty acid profile influences better body weight gain in broilers fed with sunflower oil, canola oil and soya bean oil compared to palm oil and reported with better body weight gain. The oils like sunflower oil, rapeseed oil, canola oil are rich in unsaturated fatty acids which has better intestinal absorption due to hydrolysis of monoglyceride and micelle formation compared to saturated fatty acids
(Poorghasemi et al., 2018).
Feed conversion ratio
Feed conversion ratio of broilers is presented in Table 7.
The feed conversion ratio was significantly (P<0.05) influenced due to dietary replacement of palm oil with rapeseed oil in the present study. The results of present study indicated that significantly better (P<0.05) feed conversion ratio (FCR) was observed in G
4 (100 per cent rapeseed oil) (1.84) group and G
3 (50 per cent rapeseed oil replaced group) in the basal diet (1.86). The improved feed conversion ratio might be due to ratio of saturated and unsaturated fatty acids present in broiler diets. The higher saturated and unsaturated fatty acid ratio in diet needs a higher concentration of bile salts and pancreatic lipase, which are essential for fat digestion and absorption which affect their growth
(Burlikowska et al., 2010). Hence, rapeseed oil containing diet, which has a higher ratio of UFA and SFA lead to better fat digestibility (
Nobakht et al., 2012). Similar to our findings,
Wang et al., (2013) and
Khatun et al., (2016) concluded in their study that FCR was in increasing trend with the increased levels of sunflower oil replacing palm oil when included at 6 per cent in the broiler ration.
Barzan et al., (2017) in their study also reported that canola oil supplementation had best production index in the sixth week when compared to that other oil sources like corn oil, animal fat, sunflower oil at 4 per cent. Meanwhile, canola oil and beef tallow blend had better FCR (1.84) when included at 4 per cent in broiler diet
(Poorghasemi et al., 2013). On contrary,
Ghasemi et al., (2015) and
Abdulla et al., (2017) found that the canola, palm oil, soya bean oil and linseed oil in broiler ration at 6 per cent level had no effect in feed conversion ratio.
Techno-economics
The data on techno-economics of broiler study during 42 day experimental period is presented in the Table 8. In this study cost of feed was higher in the rapeseed oil incorporated ration (R
2, R
3, R
4) than the palm oil incorporated ration (R
1). The replacement of palm oil by rapeseed oil in broiler diet has increased profit per kg live weight and it was more in G
3 (Rs.12.06) and G
4 (Rs.11.14) groups which were replaced by 50 per cent and 100 per cent rapeseed oil, respectively. Similar to our result,
Wang et al., (2013) reported that replacing palm oil by linseed oil significantly decreased (P< 0.01) the total cost of production better economic results were achieved. Similarly
Kuldipkar et al., (2017) noted that the cost per kg of meat production was less in the soya bean oil group (Rs. 47.75) followed by sunflower oil (Rs. 48.41), safflower oil (Rs. 49.28), palm oil (Rs. 51.46).