Growth Performance and Carcass Characteristics of Finisher Broilers Fed Rice Offal Based Diets Supplemented with Exogenous Enzyme

DOI: 10.15580/GJAS.2014.4.041814191 Performance and Carcass characteristics of finisher broilers fed rice offal supplemented with Natuzyme® Enzyme as a replacement for maize was investigated. A total of Seventy-two (72) 4-weeks old broilers were randomly assigned to four (4) dietary treatments with three replicates, each consisting of six (6) birds in a completely randomized design. The dietary treatments were formulated such that diets 1 (Control), 2, 3 and 4 contained 0%, 20%, 30% and 40% enzyme supplemented rice offal as a replacement for dietary maize respectively. The research lasted 28 days. Body weight gain of birds fed 20% and 30% rice offal diets were not significantly different (P>0.05) from those fed the control diet, resulting in a decreasing feed conversion ratio. Birds fed diet containing 40% rice offal consumed significantly (P<0.05) more feed than those fed other diets. Also, carcass characteristics were significantly (P<0.05) different among the treatment groups except wings and liver weight. It was concluded that rice offal contained diets supplemented with Natuzyme® can be used as an alternative source of energy in the finisher diets for broiler chickens and can replace dietary maize at the levels of 20-30% without adverse effects on growth performance and carcass characteristics. Submitted: 18/04/2014 Accepted: 12/04/2014 Published: 19/05/2014


INTRODUCTION
The rising cost of poultry feeds have continued to be a major problem in developing countries as feed cost accounts for about 65 to 70% (Nworgu et al., 1999) and 70 to 75% (Ogundipe and Sanni, 2002) of the total cost of poultry production compared to about 50 to 60% in developed countries (Tackie and Flenscher, 1995).Similarly, there has been a steady increase in the cost of conventional feed ingredients such as maize, groundnut cake, fishmeal etc in the past years as this has led to increase in the prices of animal protein sources (Adejinmi et al., 2007).Several researchers have emphasized the need for utilizing alternative feed ingredients removed from human and industrial uses (Duruma et al., 1999;Attia et al., 2001;Attia et al., 2003a;Fanimo et al., 2007;Nsa et al., 2007).
Rice milling waste (Rice offal) is an agro industrial by-product that could contribute to poultry feeding.It is available in large quantities all year round in many towns in the rice growing areas of Nigeria.The offal makes up about 40% of the per-boiled rice and contains husk, bran polishing and small quantity of broken grains.The use of rice offal to replace cereal in poultry diet has been studied (Obeka, 1985;Attia et al., 2001;Attia et al., 2003a;El-Ghamry et al., 2005).High levels of inclusion of high fibre non conventional feed stuff in poultry diets yielded negative responses because of increased fibre levels which reduce nutrients utilization and precipitate metabolic dysfunction which result in growth depression when ingested by nonruminants (Makinde et al., 2013).In order to balance utilization of these high fibre non-conventional feed stuffs, nutritionists have reported the use of exogenous enzymes for poultry.Acamovic (2001) reported that enzymes increase the digestibility of feed ingredients and reduce the incidence of wet droppings which may result from the presence of fibrous polysaccharides in diets.Similarly, Allen et al. (1997) and Attia et al. (2003b) observed that enzyme addition to monogastric animal feed reduced viscosity of ingesta in the intestine and showed a marked improvement on the various morphological effects of feeding fibrous materials to non-ruminant animals.Strategies for ensuring adequate nutrition of animals must be based on optimizing overall agricultural and livestock productivity from available resources, improving existing technologies and integrating technology that employs multipurpose crops and animals, and recycling of crop residues and byproducts as feeding stuffs for animals (Njwe, 1990).
Natuzyme® enzyme is a multi-enzyme compound of β-glucanase, xylanase, phytase, lipase, cellulose, ᾳ-amylase, protease, pectinase and a mixture of other enzymes produced by the Bio-Proton Ltd in Australia.The objective of this study is therefore; to evaluate the Performance and Carcass characteristics of finisher broilers fed rice offal supplemented with Natuzyme® Enzyme as a replacement for dietary maize.

Experimental site
This project was carried out at the student project site at Poultry Research Unit of Federal College of Agriculture, Ishiagu, Ebonyi State in 2013.

Sources of Experimental Materials
The rice offal was gotten from rice mills around Ishiagu, Ebonyi State while the Natuzyme® was procured from Natuzyme® products Company based in Enugu State.Other feed ingredients such as Maize, Fishmeal etc were bought from Enugu and Eke market in Ishiagu, Ebonyi State.

Experimental Birds and Design
A total of Seventy-two (72) four (4) weeks old Anak (unsexed) broiler chickens were used for this trial.The birds were randomly assigned to the four experimental diets representing treatments 1, 2, 3 and 4 in a completely randomized design (CRD).The diets were formulated based on NRC (1994) and meet nutrient requirements for broiler chickens.Each treatment was replicated three (3) times with 6birds per replicate.The birds were managed intensively (deep litter system).Feed and water were supplied ad-libitum.

Experimental Diets
Four diets were formulated such that diets 1(Control, without rice offal and enzyme supplementation), 2, 3 and 4 contained 0%, 20%, 30% and 40% Natuzyme® supplemented rice offal as a replacement for dietary maize.The Percentage composition of experimental diets is shown on Table 1.

Data Collection
During the period of research, data were collected on the following parameters; average initial weight, average final weight, average weight gain, average feed intake, feed conversion ratio and mortality using the replicate as the experimental unit.

Carcass Evaluation
At the end of the trial, two (2) birds per replicate were selected and slaughtered for carcass analysis.The birds were fasted overnight, after which they were bled by severing the jugular vein.They were scalded in a hot water, defeathered, and then eviscerated.All the cut parts including the organs were separated and weighed accordingly.

Statistical Analysis
Data collected were statistically analyzed using the procedure described by Steel and Torrie (1980) and significant means were separated using the Duncan Multiple Range Test (Duncan, 1995) taking P<0.05 as significance level.

RESULTS AND DISCUSSION
The proximate composition of the rice bran used in this study is presented in Table 2.All the values obtained for dry matter, crude protein, crude fibre, ash, ether extract and nitrogen free extract fall within the range reported by Aduku (1993); Attia et al., (2001); Attia et al., (2003a); El-Ghamry et al., (2005).

Growth performance
The result of the Growth performance of finisher broilers fed rice offal supplemented with Natuzyme® is presented in Table 3.The results showed that all parameters measured were significantly (P<0.05)different except the feed conversion ratio.The weight gain of birds fed the control diet was significantly (P>0.05)similar to those birds fed 20% and 30% rice offal replacement levels.The lower body weight gain recorded among birds fed diet containing 40% rice offal may be attributed to the high fibre content of the diet (Farrel, 1994;Attia et al., 2003a) which probably reached a critical level at this replacement level.Similar decline in performance had been reported by Madrigal et al. (1995).Also, Makinde et al. (2013) had earlier reported that poorer body weight gain observed among birds fed high fibre diets could be as a result of the high fibre content of the diets.Addition of Natuzyme® enzyme generally improved the utilization of the diets.This was obvious in the performance of birds fed diets containing 20% and 30% rice offal which recorded higher body weight gain and lower FCR.Attia et al., (2003a);El-Ghamry et al., (2005); Oladunjoye and Ojebiyi (2010) reported that broiler chickens can tolerate up to 20% rice bran in their diet at finishing phase when the diet is supplemented with Roxazyme G2G.Adeniji (2010) reported that pullet chicks have a good FCR and the best protein and fat retention when fed 15% dietary rice hull meal.
Feed conversion ratio was not significantly (P>0.05)different across the treatment groups.The observation that birds fed increasing levels of rice offal consumed more feed may be because of the attempt by the birds to obtain enough energy from the diet (Smith, 2001).Hence rice offal is lower in metabolizable energy than maize, and as it replaced maize in the diet, the energy level of the diet decreased.Birds usually eat to satisfy their energy requirements; the birds on the higher levels of dietary offal would consume more feed in an attempt to satisfy their energy requirements (Attia et al., 2003a;Makinde et al., 2013).The inability of the diet with 40% rice offal to bring about neither highest nor optimal weight gain comparable with the other lower levels of rice offal (0-30%) may also be due to the inability of the birds on the 40% offal to obtain enough energy from the feed they consumed.Even though the birds increased feed intake as the offal level increased, there is a limit to the stomach capacity and to what the stomach can therefore hold.The results show that it is economically advantageous to feed up to 30% rice offal diet supplemented with enzyme to finisher broilers.The present results are similar to those reported by Attia et al. (2003a); Attia et al. (2003b);El-Ghamry et al. (2005).

Carcass Characteristics
The result of the carcass characteristics of finisher broilers fed rice offal diets supplemented with Natuzyme® is presented in Table 4.There were significant (P<0.05)differences in the parameters measured except wings and liver weight.The live weight of birds fed diet containing 30% rice offal was significantly (P<0.05)higher than those fed other diets and this could be attributed to the addition of enzyme to the diets which helps to break down the fibre content of rice offal.Whereas, the lowest live weight recorded by chickens fed 40% rice offal diet, showing poor feed utilization (Attia, 2003;Attia et al., 2003a;Uchegbu et al., 2004) because of high dietary fiber.Dressing percentage was significantly higher (P<0.05) in the 0 and 20% rice offal groups compared with 30 and 40% rice offal diets.There were no considerable differences in the weight of the wings and liver (P>0.05).This observation contradicts the report of Oloyo (1991) who reported higher liver weights when broilers were fed unsupplemented guinea corn/palm kernel meal based ration.Nevertheless, thigh weight tended to increase with an increasing level of dietary rice offal and was significantly greater (P<0.05) in the 40% rice offal fed birds compared with those fed other diets.

CONCLUSION
The present findings suggest that diets contained rice offal up to 30% and supplemented with multienzymes can be used as an alternative source of energy for finisher broilers and can replace dietary maize up to 30% without negative effects on the growth performance and carcass characteristics.

Table 4 : Carcass characteristics of finisher broilers fed rice offal supplemented Enzyme (Natuzyme®) Levels of replacement of Maize with Rice offal
, c means in the same row with different superscripts are significantly different (P<0.05).SEM=Standard error of Mean