Effect of African nutmeg (<i>Monodora myristica</i>) spice in aflatoxin-infected diets on growth performance of broilers

Abstract

Fungal infected feedstuffs are denatured in nutrients and cause them to develop off flavors that often dampen the appetite of livestock and poultry. In this study, the effect of toasted African nutmeg (Monodora myristica) spice in Aspergillus flavus-infested diets on growth performance of broilers was investigated in a 2 x 3 factorial experimentthat lasted for 42 days. Three out of 6 dietary treatments were infected with 1mg of pure culture of Aspergillus flavus and toasted Monodora myristica spice included at 0%, 0.5% and 1.0% while the other 3 diets were infection-free with 0%, 0.5% and 1.0% Monodora myristica inclusion respectively. Each treatment was replicated three times at 30 chickens per replicate. Infection status was significant (P<0.05) for daily weight gain, feed conversion ratio (FCR) and protein efficiency ratio (PER). Daily weight gain, feed conversion ratio and protein efficiency ratio were 134.19g/bird/day, 39.23g/bird/day, 3.59g/bird/day and 1.10g/bird/day, respectively for the non-infected diets. The aflatoxin infection from Aspergillus flavus was observed to reduce (P<0.05) feed intake to 130.51g/bird/day and weight gain (33.67g/bird/day). FCR and PER were also reduced (P<0.05) by the presence of aflatoxin from Aspergillus flavus in the diet. Effect of Monodora myristica supplementation on feed intake, average daily weight gain, FCR and Protein efficiency ratio was significant (P<0.05) for all the measured parameters. The Feed intake, average daily weight gain, FCR and protein efficiency increased (P<0.05) as Monodora myristica inclusion level increased. Feed intake (119.8g/b/d), daily weight gain (28.90g/b/d), FCR (4.28) and PER (0.94) were observed in the Monodora-free (0%) diet. 0.5% and 1.0% levels of Monodora inclusion produced similar (P>0.05) effects on all the growth parameters but were higher than the control. The interaction of aflatoxin infection and Monodora inclusion level were significant for all the growth parameters. The interaction of aflatoxin infection x Monodora inclusion levels recorded feed intake of 107.97g/b/d, 137.36 and 146.19g/b/d respectively for 0, 0.5 and 1.0% Monodora; 22.27g/b/d, 37.87g/b/d and 40.83g/b/d daily weight gain and 4.85%, 3.63% and 3.58% FCR. The interaction effect of Monodora inclusion level in infection-free diets on the birds feed intake were 131.65g/b/d, 147.24g/b/d and 123.67g/b/d respectively for 0%, 0.5% and 1.0%. The interaction effect at 0.5% inclusion level x non-infected diet was significantly higher (41.31g/b/d) than that at 0% inclusion level on daily gain. However, the daily weight gain of 40.83g/b/d observed in the interaction of 1.0% Monodora level x aflatoxin -free diet similar (P<0.05) to that observed in the 0.5% inclusion level. The feed conversion ratio produced by the interactions at the three different levels (0, 0.5 and 1.0%) in the Aspergillus-free diets were (P>0.05) 3.71, 3.57 and 3.49 respectively while PER were (P<0.05) 1.05, 1.13 and 1.11 respectively. The Monodorafree diet recorded 9.26% drumstick, 2.26% liver 0.65% kidney and 2.43% gizzard, while the diet that had 0.5% Monodora myristica yielded 2.12% liver and 2.29% gizzard. Inclusion of Monodora up to 1.0% recorded 1.63% liver weight. Aspergillus flavus alone caused a reduction in live weight, dressed weight, thigh, kidney, breast meat, gizzard and an  enlargement in the liver. Monodora myristica inclusion level also affected (p<0.05) all the parameters except dressed weight, thigh and back cut. Kidney and liver were observed to decrease as the level of inclusion of Monodora myristica increased. The interaction of Monodora myristica and Aspergillus flavus on the parameters were significant (p<0.05). From the results, Monodora myristica may be beneficial to poultry farmers, since about 90% of the poultry feed ingredients especially grains are constantly exposed to aflatoxin infection from Aspergillus flavus and other mycotoxin infections which hinder maximum nutrient utilization and affect the rate of conversion of feed.

Keywords: Aflatoxin, Monodora Myristica, Aspergillus flavus. growth performance, broiler birds