The influence of polyethylene glycol inclusion in <i>Vachellia tortilis</i> leaf meal on nitrogen balance in growing pigs

The incorporation of polyethylene glycol (PEG), a tannin binding agent, in high tannin feedstuff is known to prevent tannin-protein complexes. Environmental contamination with nitrogen-containing products in manure is a topical issue in the tropics. The objective of the study was to determine the extent to which the incorporation of PEG in Vachellia tortilis leaf meal improved nitrogen balance, serum iron, and phosphorus in growing pigs. Forty-eight clinically healthy male PIC pigs (31.3 ± 1.28 kg; Landrace x Large White) were allotted to individual pens in a completely randomized design, with eight pigs per treatment. They were offered a diet that contained 150 g V. tortilis /kg dry matter (DM). The diets were treated with 0, 5, 10, 15, 20, and 25 g PEG/kg. As PEG inclusion increased, serum iron concentration also rose until it reached a plateau. Nitrogen (N) utilisation and retention significantly increased linearly with PEG inclusion. Nitrogen excretion through faeces and urine significantly decreased linearly when increasing the amount of PEG in V. tortilis leaf meal in feed offered to pigs. Nitrogen utilization significantly increased linearly as the inclusion of PEG rose. It can be concluded that the inclusion of PEG increased N balance. Keywords: average daily gain, nitrogen intake, nitrogen retention, phytate, polyphenolic compounds