Response of Broiler Chickens to Different Dietary Crude Protein and Feeding Regimens

Five isocaloric (3200kcal/kg) diets were used in an experiment designed to investigate the effects of dietary crude protein (CP) and feeding regimens on broiler performance. Day-old broilers were randomly distributed into four groups using a completely randomized design. Each group was replicated three times with ten broiler chicks per replicate. The experiment lasted for eight weeks. Broilers in group 1 received 23% CP from 0 to 3 weeks, 20% CP from 3 to 6 weeks and 18% CP from 6 to 8 weeks, while broilers in group 2 received 23% CP between 0 and 6 weeks and 18% CP between 6 and 8 weeks. Besides, broilers in group 3 were fed 23% CP from 0 to 4 weeks and 16% CP from 4 to 8 weeks, whereas group 4 was given 18% CP from 0 to weeks. Water was supplied ad libitum for broilers in the different dietary groups. A metabolic trial was carried out on the third week of the experiment using a total collection method. Proximate analyses of diets and faecal samples were performed according to the methods outlined by the Association Of the Official Analytical Chemists. Results at market age showed that broiler performance with respect to feed intake, weight gain, feed to gain ratio and water intake were not significantly influenced by CP regimens (p>0.05). Furthermore, CP regimens did not significantly influence broilers liveability (p>0.05). Protein retention, fat utilization and available fiber were not significantly influenced among treatments (p> 0.05). Economic data showed that cost to benefit ratio of producing broilers was comparable among broilers for all CP regimens used in this trial (p>0.05). It was concluded that a single diet of 18% CP and 3200kcal/kg metabolizable energy would be most suitable and convenient for farmers who are engaged in on-farm feed production for broilers as compared with the standard feeding regimens of broiler starter and broiler finisher diets.


INTRODUCTION
Satisfying the nutritional requirements of a particular class of livestock is rapidly becoming a difficult task.This is due to scarcity and high cost of feed and feed ingredients.Meeting the protein needs of broilers represents a very substantial part of the cost of feeding (Oyedeji & Atteh, 2003).Although National Research Council (NRC, 1984) recommended a feeding standard for broilers among other classes of livestock under temperate climatic conditions, this has not been totally practicable in the tropics for the obvious reasons of environmental differences and type and quality of available feed ingredients.Efforts have been made to determine feeding standards for broilers under tropical environments (Aduku, 1992 andOlomu, 1995).However, due to high cost and scarcity of feed and feed ingredients poultry farmers still occasionally and haphazardly mix one or two ingredients together without due consideration for age and nutrient requirements of the class of birds involved.Also, most of the farmers operate in the rural and sub-urban areas with bad and inadequate access roads and transportation.Thus, it is difficult to reach areas where complete feed can easily be found on time; hence the practice of on-farm feed production.
This study was designed to investigate the effects of different dietary protein regimens on broiler performance with the main objective of finding the most suitable and convenient feeding standard for farmers who want to practice on-farm feed production.

MATERIALS AND METHODS
One hundred and twenty (120) day-old Anak broilers were housed in an electrically heated battery brooder and fed the first, the second or the third of the experimental diets described in Table 1.The experimental diets were formulated to be isocaloric, each containing 3200kcal/kg of metabolizable energy.Therefore treatments consisted of variations in the levels of dietary crude protein (CP).There were four (4) treatment groups, each with three (3) replicates of ten (10) birds per replicate.Broilers in Group 1 were fed diets with 23% CP from 0 to 3weeks, 20% CP from 3 to 6weeks and 18% CP from 6 to weeks, while those in Group 2 were fed diets with 23% CP from 0 to 6 weeks and 14% CP from 6 to 8 weeks.Broilers in Group 3 were fed 23% dietary CP from 0 to 4 weeks and 16% CP from 4 to 8 weeks, whereas those in Group 4 were fed 18% CP from 0 to 8 weeks.Feed and water were supplied ad libitum throughout the study.Weekly data of feed intake, weight gain and water intake were collected.A metabolic study was conducted during the 3 rd week of the experiment.Weighed quantities of feed were supplied and faecal samples collected over a 72-hour period using a total collection method.The collected fecal samples were oven-dried at 60 o C for 24 hours, weighed and ground prior to chemical analysis.The proximate compositions of nutrients in the feed and fecal samples were determined using methods of AOAC (1980).
The considered economic parameter was determined using the prevailing market prices of the diets used, costs of medication and that of broilers on live weight basis.
The data collected were analyzed using analysis of variance (ANOVA).Significant test was conducted using Duncans Multiple Range Test (Duncan, 1955).All statistical analyses were done in accordance with the methods of Steel and Torrie (1980).

RESULTS
Data on feed intake, growth performance, water intake, cost:benefit ratio and mortality percentage as affected by CP regimens are summarized in Table 2. Feed intake, weight gain and feed to gain ratio were not significantly affected by CP treatment (p<0.05).Water intake was also similar among treatments (p>0.05).CP treatment did not affect broilers liveability significantly (p>0.05).Cost:benefit ratio was not significantly influenced by any of the CP regimens (p>0.05).
The effect of dietary protein regiments on nutrient utilization is as shown in Table 3. Results showed that protein retention, fat utilization and available fiber were not significantly influenced by any of the dietary protein treatments (p>0.05).

DISCUSSION
The reduction in body weight gain and feed intake as recorded in this study among broilers subjected to different crude protein regimens appeared not to be significant.However, a cursory look at the trend of results observed for both feed intake and body weight would show that with one more replicate and more birds per replicate these data might be statistically metabolizable energy and the other age-related CP formulations.However, a single diet would be more straightforward for farmers who are operating on-farm feed production since there would not be the inconvenience of changing from one diet to another in the course of 8 or 9 weeks when broilers are expected to attain market weight.

Table 1 -
Ingredient composition (%) and proximate analysis of different diets fed to broilers from 0 to 8 weeks of age.