The effect of globin, a water-soluble emulsifier, on broiler performance

Globin, produced by hydrolysis of porcine haemoglobin into haem and globin, is a water-soluble protein with a strong emulsifying capacity (1g globin can emulsify 1000g soya oil). We tested the effect of the inclusion of 0,05% of globin in broiler diets containing a combination of soya oil (S) and palm fat (P) on average daily growth (ADG) and feed conversion (FC). Three hundred male broiler chickens (Ross 308) were equally divided in 10 pens of 30 birds (5 pens per treatment ; 2 treatments : Control (C) and Globin (G)). The experimental diets were formulated with wheat as the main cereal in a 3 phase feeding program (starter : 1-10 days, 1%S + 2,75%P, 12,12MJ ME/kg ; grower : 11-21 days, 1,5%S + 3,1%P, 12,33MJ ME/kg ; finisher : 21-42 days, 1,5%S + 3,7%P, 12,5MJ ME/kg). All birds received feed (meal) and water ad libitum. Results were analysed by ANOVA. Final body weight at 42 days of age was 2751g for C and 2757g for G. For the whole trial period there was no effect on ADG (C : 64,4 g/d ; G : 64,5 g/d) but FC was clearly lower in the G group (C: 1,727; G: 1,679 (P=0,102)). No significant effects on performance were found in the starter period. In absolute values, FC on the G diet was 1,5% lower than on C (1,620 vs 1,595). In the grower-finisher period (11-42 days) ADG was 79g/d for both treatments. In this period there was a clear improvement of FC on diet G (C: 1,740 ; G: 1,685 (P<0,10)). As a conclusion, addition of 0,05% of globin from starter to finisher clearly reduced FC with 2,9%. As ADG was not different form the control, this improvement was due to a better digestibility of the feed. Since globin has a high emulsifying capacity, increased feed efficiency is most probably due to increased availability of energy out of the added fat (S + P) when compared to the control group.