Nitrogen balance and morphometric traits of weanling pigs fed graded levels of wild sunflower (tithonia diversifolia) leaf meal

Abstract

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.
Key words: Morphometric trait, nitrogen balance, pigs