Determination of optimum dietary energy and protein levels for confined early-stage Fulani Ecotype chickens

Introduction

Local chickens constitute a majority of the estimated 170 million poultry birds found in Nigeria and contribute substantially to annual egg and meat production (> 90%) for family consumption and for sale (FAOSTAT 2012; Khobondo et al 2015). In most developing countries these birds are mainly managed extensively in resource-limited/poor or rural households and thereby contribute substantially to their food security.

However, such local chickens are characterized by low productivity from factors such as low genetic potential, poor management practices and high prevalence of diseases (Pedersen 2002; Sonaiya 2004; Lwelamira 2007). Consequently, in order to capitalize on the economic importance of local chickens, breeding programs to improve their genetic potential and also enhance conservation of indigenous genetic resources such as African Chicken Genetic Gains (ACGG; https://africacgg.net) have been set-up. Paradoxically, such programs and other genetic evaluations will most likely be conducted under intensive management for extensively managed birds. Therefore, it is imperative to evaluate such birds under intensive or semi-intensive management in order to aid in the selection of most suitable types for improvement.

In Nigeria, two ecological classes considered to be most important in the classification of indigenous chickens are the Fulani and Yoruba ecotypes (Yakubu et al 2009). Further, Fulani ecotype (FEC) is considered to be a heavy breed while the Yoruba ecotype a light breed (Momoh et al 2010). The view that FEC is superior to other ecotypes in terms of body weight and by extension growth rate, probably makes it most suitable for improvement in meat production. Most of the studies on FEC had been on breeding and genetics concerned mainly with genetic diversity, phenotypic and morphometric characterization, egg traits, hatchability (Fayeye et al 2005; Mancha et al 2006) and growth and reproductive performance (Ibe 1993; Sola-Ojo et al 2013). Surprisingly, in these studies, FEC raised intensively were fed with feed designed for broiler chickens, which may not be appropriate nutritionally because commercial hybrid broiler chickens are fundamentally different in growth performance. In addition, generally in developing countries, attention to nutritional requirements for local chickens especially energy and protein have been varied, inconclusive or relatively non-existent at the early stages of growth, particularly from 0-5 weeks (Khobondo et al 2015). Nevertheless, Nakkazi et al (2015) suggested 2800 kcal ME/kg with 18% CP ideal for Ugandan local chicks and Nguyen and Bunchasak (2005), 3000 kcal ME/kg with 17-18% CP for Betong chicks from 0-6 weeks of age but none for FEC.

The very limited nutritional data on performance of early-stage local chicks may be due to the difficulty in obtaining large flock of day-old chicks or adequate quantity of eggs to hatch from smallholder farmers and the absence of formal breeding centers. For example, FEC are kept in small units by isolated family groups of the Fulanis in kraals (Fayeye et al 2005). Therefore, the objective of this study was to estimate the optimum energy and crude protein (CP) levels for early growth performance of confined Fulani ecotype chickens.

Materials and methods

The experiment was carried out at the Poultry Unit of the Teaching and Research Farm of Obafemi Awolowo University, Ile-Ife, Nigeria. A total of 180 day-old local Fulani ecotype chickens (FEC) used for this experiment were from eggs picked from a breeding flock at the farm and hatched at a commercial hatchery. The birds were raised on a deep litter system under natural day light in open-sided pens in two phases (0-6 and 6-12 weeks) from 0-12 weeks of age, patterned after the typical feeding management for broiler chickens. The chicks were fed ad libitum starter diets (Table 1) for the first six weeks and finisher diets (Table 1) from 6 – 12 weeks of age. In each phase, birds were randomly allocated to one of six dietary treatments replicated thrice, with ten birds per replicate in a factorial arrangement (3 x 2) of energy at 3 levels and protein at 2 levels. For both phases, energy was fixed at 2900, 3000 or 3100 kcal ME/kg levels and each with 20 and 22% CP or 18 and 20% CP for 0-6 and 6-12 weeks, respectively (Table 1). Drinking water was provided ad-libitum.

Determination of optimum dietary energy and protein levels for confined early-stage Fulani Ecotype chickens - Image 1

Data was collected and calculated on body weight, feed intake, daily body weight gain and feed conversion ratio. At the end of twelve weeks, three birds were randomly selected per replicate for slaughtering, evaluation and comparison of basic carcass traits. The birds were starved overnight but had access to water. The fasted live weight was taken before slaughter. Birds were slaughtered by severing the neck with a sharp knife. They were then de-feathered after scalding in warm water. Carcass was evaluated on live, dressed, thigh, drumstick, wing and breast weights. Carcass yield was determined as ratio of dressed weight to live weight and carcass parts were expressed as proportions of the dressed weight.

The experiment was a completely randomized design in a factorial arrangement. To assess the effect of energy and protein on growth performance and carcass traits, factorial ANOVA of SAS (2000) was performed according to the following model:

Y_ijk = µ + T_i +β_j + (Tβ)_ij + ε_ijk

where, Y_ijk =response (growth performance and carcass characteristics) of the k^th bird to the i^th energy of the j^th protein; µ = general mean; T_i = effect of i^th energy; β_j= effect of j^th protein; (Tβ)_ij = interaction effect of the i^thenergy and j ^th protein; ε_ijk = random error. Significant differences among treatments were separated at 5% level by Duncan’s multiple range test.

Results and discussion

Table 2 shows the results for the effect of different energy and protein levels on growth performance of FEC from 0-12 weeks. At 0-6 weeks, birds fed 3000 kcal ME/kg with 22% CP were similar (P>0.05) to others for feed conversion but superior (P<0.05) in body weight and feed cost/gain (Table 2). There was a tendency for heavier body weights at higher CP levels and energy with protein interaction (P = 0.06; E x CP: P = 0.07). Previous work had reported higher body weights as dietary energy and protein levels increased (Pesti and Smith 1984; Nguyen and Bunchasak 2005; Miah et al 2014). However, birds on 2900 kcal ME/kg had the highest growth rates (P<0.05) with highly significant interaction (P<0.05) with 22% CP but was not translated into heavier body weights probably because of insufficient dietary energy support for this. Pesti and Smith (1984) found that when young chicks are fed inadequate levels of energy compared to protein it may affect their capacity for optimum body weight for profit maximization.

Birds fed 3100 kcal ME/kg ate the most feed (P<0.05), regardless of CP levels, but had the least body weight, indicating inefficient utilization of energy by overconsumption of feed. Nguyen et al (2010) affirmed Brown and McCartney (1982) observation in Betong chickens that chickens tended to overconsume energy rich diets that have less than corresponding CP levels in a quest to meet protein requirements. This result contradicts, in part, the view that chickens eat to meet energy to protein ratio (NRC 1994). Pesti and Smith (1984) had found that what is more important is the energy and protein values not energy to protein ratio and that body weight increased with increasing levels of protein and energy. This means that inferences on growth performance based solely on dietary energy may be misleading if dietary CP is not considered.

In contrast, Nakkazi et al (2015) recommended a low energy (2800 kcal ME/kg) and protein (18%) diet for semi-scavenging or intensively-reared Ugandan local chicks (0-6 weeks). Interestingly, in this study (Nakkazi et al 2015) maximization of returns in terms of lowest feed cost/gain was not considered, which appeared to be better for birds fed 3000 kcal ME/kg with 20% CP. Nevertheless, since local chickens are heterogeneous, several factors especially genotype or breed or mature body weight may be responsible for differences in the results from different studies. Richards and Proszkowiec-Weglarz (2007) suggested that genotype is key in regulating feed intake, energy expenditure and body weight in poultry.

Although FCR was similar (P>0.05) across treatments, there was a tendency for more efficient utilization of energy and protein for body weight (E: P = 0.056; CP: P = 0.07; E x CP: P = 0.07) by birds fed 3000 kcal ME/kg/22% CP compared to others. Values and trend for FCR obtained were similar to those by Nakkazi et al (2015) from Ugandan local chicks (0-6 weeks) but significantly higher than those by Sola-Ojo and Ayorinde (2009) for FEC (0-10 weeks) which had values surprisingly at par or better than obtained for commercial hybrid broiler chickens.

Determination of optimum dietary energy and protein levels for confined early-stage Fulani Ecotype chickens - Image 2

Final body weights at 6 weeks were higher than obtained by Sola-Ojo and Ayorinde (2009) for FEC but lower than that obtained by Nakkazi et al (2015) for Ugandan chickens at the same age, most probably due to genotype influences as mentioned earlier.

In this study, FEC (0-6 weeks) increased body weight as dietary energy and protein levels increased up to the point that the CP level remained adequate for corresponding weight gain. The optimum energy protein combination at this stage of growth appeared to be 3000 kcal ME/kg with 22% CP for body weight, feed intake, FCR and feed cost/gain. However, for growth rate, 2900 kcal ME/kg/22% CP seems optimum. Therefore, an energy value probably mid-way between 2900 and 3000 may be optimum for this stage of growth but requires further investigation.

At 6-12 weeks (Table 2) dietary energy, CP and their interaction significantly affected final body weight. Birds previously on 3000 kcal ME/kg and 22% CP now switched to 3000 kcal ME/kg and 20% CP, were similar (P>0.05) to other combinations for mortality, feed intake, FCR and body weight gain but superior (P<0.05) in final body weight and had the least feed cost/gain. This was similar to the study by Nguyen et al (2010), where different energy and protein combinations did not affect FCR and feed intake of 6-12 week-old Betong chickens but birds fed highest CP had highest weight gain. Evaluation of the whole period (0-12 weeks) confirmed the results of the individual phases (Table 2).

Table 3 shows the effect of different energy and protein levels on carcass characteristics of FEC at 12 weeks. There was no significant effect (P<0.05) of energy or protein levels and interaction on yields (%) of carcass (dressing %), breast, thigh, drumstick and wings. This was different from the results of Nguyen et al (2010) where high energy levels increased carcass yield, decreased wing and leg yield but similar in no effect on breast yield. This may have been due to genotype effects (Richards and Proszkowiec-Weglarz 2007).

Determination of optimum dietary energy and protein levels for confined early-stage Fulani Ecotype chickens - Image 3

Conclusion

Optimum dietary energy and protein for FEC was 3000 kcal ME/kg and 22% CP for 0-6 weeks, and 3000 kcal ME/kg with 20% CP for 6-12 weeks of growth.
These results will be important for improvement programs on indigenous chickens.

Acknowledgement

Sincere appreciation goes to iLinova for the support in the accomplishment of this study. Gratitude also goes to Mr. Dare Akinniyi Lawrence for the provision of the day-old Fulani ecotype chickens used in this study.

This article was originally published in Livestock Research for Rural Development 28 (9) 2016. Volume 28, Article #164.