Inclusion of Kalahari melon (Citrullus lanatus) meal in lamb diets: Effects on growth and meat quality

Abstract

The study was carried out to evaluate the effect of substituting SBM with KMOC on growth performance, economic evaluation, protein utilization efficiency, blood parameters, carcass characteristics, meat quality and internal organs of lambs. Forty Meatmaster lambs were used in the experiment. Lambs were randomly assigned to five dietary treatments in a completely randomized block design and fed in individual pens for 54 days. Animals were allocated five dietary treatment groups with inclusion levels of KMOC: 0% (control), 25 %, 50%, 75%, and 100%. Each treatment was replicated 8 times. Lambs in the different dietary treatment groups had initial weights (IW) of 27.6± 3.21Kg.There were significant differences (P < 0.05) in overall FW, ADFI, ABWG, ADG , FCR fed KMOC in between treatment groups The lambs fed a 50% KMOC diet had the highest (P< 0.05) BWG, ADFI and ADG.ADFI increased with the increasing levels of KMOC in the diet but decreased at 75% and 100% KMOC inclusion levelsDiet significantly affected PC and PER. Lambs fed a 50% KMOC diet had the highest overall PC (162.05 ± 5.16) whilst a 100% diet had the lowest overall PC value (118.34± 5.16). Diet did not affect SGR and GE SGR and GE declined with increasing levels of KMOC in diets. Diet significantly affected the RBC, haemoglobin, MCV, WBC, platelets, neutrophils, lymphocytes, monocytes, neutrophils and lymphocytes. The RBC was lowest (14.73±0.85) in the lambs fed the 50% KMOC diet and the highest (16.81±1.04) in the diet containing 75% KMOC. Generally, the lambs fed the 25% KMOC-containing diets had the lowest values (8.55±1.79) for the WBC compared to other treatment groups. However, diet did not affect haematocrit value and MCH. Diets did not significantly (P < 0.05) affect CA, TP, ALB, GGT and AMY. Lambs fed the 25% KMOC had the highest levels (P <0.05) of TALB (Total albumin) (25.60±5.77), lowest observed by 75% KMOC-fed lambs (17.92±9.76). Diet did not significantly (P < 0.05) affect GLU, SMDA, UREA, ALKP, LIPA, PHOS and GLOB. Spleensomatic indices (SSI) were not influenced by diet. There was significant difference on carcass profits, GI, feed, TVC and GM. The higher the inclusion levels of KMOC the higher the gross margin. And this proves to be cost-effective to replace SBM with KMOC. The results indicate that diet significantly affected dressing %, HCW and CCW. Lambs fed the control diet had the highest HCW (18.02 kg ±1.10). The CCW was high in lambs fed 50% KMOC (16.15 kg±0.99) as expected. The lambs fed higher levels of KMOC had the lowest values on carcass parameters except Chilling loss. Nevertheless, the lambs fed 25% of KMOC in diets marginally had higher dressing percentages (50.30±2.23) although it was significantly different and declined as inclusion levels increased. The carcass length was high in lambs fed 50% KMOC (70.43cm ±2.07), followed by those fed a 25% KMOC (67.06.cm±2.07). The lambs fed a 50% KMOC diet had the heaviest heart (155.00g ±6.33) while lambs fed with a 100% KMOC diet had the lowest weight (116.87g±6.33). However, kidney weights were highest (P < 0.05) in lambs fed control (109.37±4.46) as compared with all other treatments. The spleen and lungs were significant higher (69.37±5.74 and 380±23.55) in 50% KMOC. Diet significantly affected (P < 0.05) meat colour coordinates, water holding capacity, cooking loss, dripping loss and meat shear force in response to incremental levels of KMOC. Meat temperature was higher (P < 0.05) for carcasses fed 75% KMOC. The highest meat colour coordinates were observed in lambs fed 100% KMOC diets with L* (34.15± 0.78) and b*(2.87 ± 0.44). The highest a*(13.24 ± 0.52) was observed in lambs fed 75% KMOC. In terms of WHC % the lambs fed 75%, KMOC had the lowest value (9.76%±1.76). The highest value observed was in lambs fed 25% KMOC (12.87%± 1.76). The dripping loss was observed to be higher in the lambs fed 100% KMOC (36.83 ±2.98). The lowest cooking loss was observed in lambs fed 50% KMOC (32.08 ±2.98), while the highest was observed in lambs fed 100% KMOC (36.83±2.98). The lambs fed 75% KMOC had the highest (P < 0.05) and shear force texture (16.50N). The lowest meat texture (P > 0.05) was observed from diets containing 100% KMOC (12.19 N). The findings of the study suggest that KMOC can partially substitute SBM up to 50% without compromising the health of lambs.