Growth performance, meat quality, and haematological parametersinmutton merino lambs : effects of dietary replacement of soyabean meal with canola cake
The objective of this study was to determine growth performance, hematology, meat quality and sensory characteristics of lambs fed Canola (Brassica napus) cake as a replacement for soyabean meal (SBM). Nineteen lambs with an average body weight of 23 kg ± 2.64 kg were used. The lambs were randomly assigned to five dietary treatments in a completely randomized design and fed in individual feeding pens for 60 days. The soya bean meal (SBM) in the control ration was replaced with Canola meal at 0% (control), 25 %, 50%, 75%, and 100% inclusion levels. There was no significant difference (P > 0.05) in the cumulative live weights and body weight gain of the lambs. The average daily gain (ADG) (0.17 - 0.20 kg/day), average daily feed intake (ADFI) (1.15 - 1.21 kg/day), feed conversion ratio (FCR) (3.09 - 3.41) and slaughter weight (SL W) (33 .2 - 34.7 kg) also showed no significant differences (P > 0.05) between the dietary treatments. The hematology blood count showed no significant difference in red blood cell (RBC) count (9.54 - 12.8 xl012/L) and haematocrit (HCT/PCV) (29.3 - 38.5%) values. The animals were slaughtered at the end of feeding trial to determine meat quality characteristics. There was no significant effect (P > 0.05) of dietary treatment on carcass weight (CWT) (16.5 - 18.7 kg), cold carcass weight (CCWT) (16.2 - 18.2 kg), carcass length (78.7 - 83.7 cm), ultimate meat pH (pHu) (5.70 - 5.81) and temperature (9.07-10.7 °C). Lamb meat from different dietary treatments showed no differences in terms of water holding capacity (0.36-0.38), cooking loss (10.8- 13.6%), drip loss (2.27 - 3.67 %), evaporation loss (8.53 - 10%), and thaw loss (0 - 0.13%). The shear force measurements were also similar, ranging from 1.67 to 2.17 kg. Similarly, diets had no effect on meat colour parameters. For all the treatment groups, lamb meat was rated similarly by the sensory panels. From the foregoing, it can be concluded that Canola meal is a suitable alternative for soyabean meal in fattening lamb diets and can produce comparatively good quality meat that is highly acceptable and it does not seem to compromise health of the animals. South African feed companies can therefore shift from using soyabean meal to canola meal in sheep ration to minimize costs. The results of this study show that livestock feed companies and farmers can incorporate canola meal in fattening lambs ration as a major protein source and this will also help to reduce the cost of importing soyabean meal in the country.