Leaves of
Tithonia diversifolia
(wild sunflower) were harvested, processed and subsequently referred to as
Tithonia diversifolia leaf meal (TDLM). Proximate composition and amino acid analyses revealed that TDLM is a relative rich protein source at 20.6% crude protein (CP) content. Lysine, leucine and isoleucine were particularly abundant in TDLM and compared favourably with conventional protein sources such as groundnut cake and hen’s whole egg. Pre-feeding trial on standard grower pig diet for 10 days revealed uniform growth among the 24 Large White breed experimental pigs allotted into 4 treatments. Thereafter, a 63-day feeding trial was conducted using four diets containing 19.0% CP and digestible energy value of about 12.55MJ/kg. TDLM progressively replaced soybean at 0 (control), 10, 20 and 30% inclusion levels in diets 1, 2, 3 and 4, respectively. There was a significant reduction (p≥0.05) in daily feed consumption for pigs across the experimental diets with a range of 390.8 g/day in pigs on the control diet to 261.4 g/day in pigs on diet with 30% TDLM. Average daily weight gain (AWG) and feed conversion ratio (FCR) had a similar trend with AWG varying significantly (p≥0.05) from 114.3 g/day for pigs on the control diet to 11.7 g/day for pigs on diet with 30% TDLM. Nitrogen retention (NR) had the highest significant (p≥0.05) value of 2.87 g/N/pig/day for pigs on 10% TDLM followed by 2.26 g/N/pig/day for pigs on the control diet. There were negative net nitrogen retention values of -2.60 g/N/pig/day and -1.70 g/N/pig/day for pigs on 20% and 30% TDLM inclusion levels, respectively. Body length ranged from 55.3 to 61.8 cm; knee to floor ranged from 14.4 to 16.3 cm; and hock to floor ranged from 18.4 to 19.3 cm. Pigs on 10% TDLM based diet surpassed the control diet in body length. Other parameters (live weight, height at withers, chest depth and chest girth) had slightly varying (p≥0.05) values for pigs across different diets with pigs on the control diet and diet with 10% TDLM inclusion level having consistently higher values. The similarities in most parameters determined for pigs on control diet and 10% TDLM strongly suggests the suitability of TDLM at inclusion levels not exceeding 10%. We concluded that further processing techniques may be used to facilitate better utilization of TDLM in pig rations.
