Effect of Moringa oleifera leaf meal on finisher pig growth performance, meat quality, shelf life and fatty acid composition of pork
AbstractThe effect of dietary inclusion of Moringa oleifera leaf meal (MOLM) on the feed conversion ratio (FCR) of finisher pigs, physico-chemical meat quality, fatty acid (FA) composition and shelf life of pork was investigated. A six-week feeding trial was conducted with 24 Large White x Landrace gilts aged 14 weeks. Each pig was housed individually and randomly allocated to one of four dietary treatments, containing 0%, 2.5%, 5% or 7.5% MOLM, with six replicates per treatment. Feed intake was measured daily, pig liveweight was measured weekly, and average daily gains (ADGs) and FCR were calculated. Pigs were slaughtered at 20 weeks old and measurements of backfat thickness, pH45min and pH24h were taken. Muscularis longissimus thoracis et lumborum muscle samples from each carcass were analysed for physico-chemical quality. Muscle, subcutaneous fat and feed samples were analysed for FA composition and health lipid indices of atherogenicity (AI) and thrombogenicity (IT) were calculated. A 10-day shelf-life study was conducted, during which instrumental and sensory meat colour and odour were assessed. Pigs fed 7.5% MOLM had significantly higher average daily feed intakes (3.56 kg/day) than pigs fed 0%, 2.5% and 5% MOLM (3.05, 3.14 and 3.07 kg/day, respectively). The FCR of pigs fed 0%, 2.5% and 5% MOLM did not differ significantly (3.34, 3.44 and 3.22, respectively). However, the FCR of pigs fed 7.5% MOLM was significantly poorer (3.78). No significant differences were observed for carcass and physico-chemical quality traits. MOLM inclusion improved shelf life, as meat samples from MOLM-fed pigs exhibited significantly prolonged acceptability of colour and odour during 10 days of refrigerated storage. Although the n-6 : n-3 FA ratios of the dietary treatments containing MOLM were significantly improved (T1 = 35.45, T2 = 22.08, T3 = 14.24, T4 = 15.90), no significant differences were observed for this ratio in the fat composition of the meat or subcutaneous fat samples between treatments. A significant reduction in intramuscular fat and stearic acid content was observed with increasing levels of MOLM. However, all other FA profiles, ratios and health lipid indices did not differ significantly across treatments. In conclusion, up to 5% MOLM may be included in finisher pig feed with no negative effect on feed conversion efficiency, carcass and meat quality traits, and may improve shelf life of pork. However, inclusion levels of 7.5% MOLM may lower FCR. The MOLM inclusion significantly improved the FA composition of the feed, but did not produce the desired improvements in FA composition of meat, probably because of the prominence of fat deposition by de novo lipogenesis in finisher pigs rather than direct incorporation of dietary fatty acids.
Keywords: Moringa oleifera, anti-nutrient factors, fatty acid ratios, pork colour, pork odour