On-station performance evaluation of improved tropically adapted chicken breeds for smallholder poultry production systems in Nigeria

Background Availability of appropriate genetics is important for the development of smallholder poultry (SHP). The biological potential of improved dual purpose chicken germplasms was evaluated in Nigeria. Methods A total of six breeds (Fulani, FUNAAB Alpha, Kuroiler, Noiler, Sasso, and Shika-Brown) were tested on-station, in deep litter houses at two test centres (Public and private facility) for 504 days. Birds were fed ad libitum for the first 140 days after which restricted feeding was practised. Result Lowest and highest hatchability of eggs set was 55% (FUNAAB Alpha) and 89% (Sasso), respectively. At 140 days, male live weights were 200%–300 % higher than the local chickens (975 g) except Shika-Brown (152%) and Fulani (135%). Lowest (p < 0.05) age at first egg was 119 days for Shika-Brown and 120 days for FUNAAB Alpha and Kuroiler. Highest hen-housed egg production was 192 for Shika-Brown, and feed intake per dozen eggs was lowest (p < 0.05) for Shika-Brown (2.9 kg) and FUNAAB Alpha (2.9 kg). Mortality rate of the locally sourced breeds (Fulani, FUNAAB Alpha, Noiler, and Shika-Brown) was significantly lower (p < 0.05) than the foreign-sourced breeds (Kuroiler, Sasso) during brooding, growing and laying. Conclusion Results from this study identified FUNAAB Alpha and Noiler as being more suitable for dual-purpose functions (egg and meat), while Sasso and Kuroiler (meat) and Shika-Brown (egg) were observed to be better suited for single purpose functions. These findings could guide the introduction of smallholder poultry-specific hybrid germplasms for the development of the smallholder poultry production systems in Nigeria.


Introduction
Smallholder poultry (SHP) is defined as poultry keeping by households using family labour, locally available feed resources obtained largely through scavenging by a flock of less than 100 birds, of unimproved or improved breed (Sonaiya, 1990). The characteristics and importance of SHP are fundamentally similar in rural and peri-urban farming communities irrespective of the sociocultural factors and agroecological conditions (FAO, 2010). The low productivity of the SHP production systems (as characterized by high mortality, low egg numbers, and poor live performance) has resulted in the demand by SHP producers for "better and bigger" birds in Nigeria (ACGG Nigeria baseline data, 2016). Such "better" birds are best provided not by commercial/industrial poultry germplasms but by SHP-specific hybrid germplasms (SHP-SHG) which are improved dual-purpose birds (meat and egg production) that incorporate genes for higher productivity and performance into the hardiness of locally adapted chickens.
The introduction of SHP-SHG has been successfully tested on-farm, under scavenging management systems (i.e. Backyard poultry), in Bangladesh for the Sonali chickens (FAO, 2015), and in Uganda with the Kuroiler (Galukande et al., 2016;Sharma et al., 2015). However, under the African Chicken Genetic Gains project in Nigeria, the testing of six SHP-SHG (Fulani, FUNAAB Alpha, Noiler, Kuroiler, Sasso, and Shika-Brown) was conducted both on-farm, as a farmer-led experimentation, and on-station (https://africacgg.net). The on-station research condition (controlled environment) was adopted as an evidenced-based approach of investigating the biological potential of SHP-SHG under intensive management systems, with optimum feeds and feeding, housing, biosecurity, and health measures. Hence, the objective of this study was to evaluate the growth performance, egg production, and mortality rate of the selected SHP-SHG, under on-station conditions in Nigeria.

Study locations
The on-station test was conducted at a private (Fol-Hope Farms, Ibadan, Oyo State) and public (Federal University of Agriculture, Abeokuta, Ogun State -FUNAAB) facility located within the southern Guinea savanna, and dry lowland rainforest of Nigeria, respectively. The birds were tested in isolated poultry houses sited away from other birds at the test centres. The coordinates of the two test centres, within the respective agroecologies, were: latitude 7°N 20' 25", longitude 3°E 58' 14" and altitude 4.5 m (Fol-Hope station), and latitude 7°N 13'28", longitude 3°E 26' 3"and altitude 133.8 m (FUNAAB station All the chicks were hatched onstation, and a total of 1,939-day-old chicks of both locally sourced breeds and foreign-sourced breeds were brooded from 0 to 42 days (d). The birds were sexed at 42 days, and grown separately until 140 days for males and 504 days for females. The population density was 10 chicks/m 2 , 7 birds/m 2 , and 5 birds/m 2 during brooding, growing, and laying phases, respectively. Commercial feed (Chick mash: 2,993 kcal ME/kg, 22.3% CP; Grower mash: 3,013 kcal ME/kg, 17% CP) and water were available ad libitum during brooding and growing phases. During the laying phase (Layer mash: 2,500 kcal ME/ kg, 16.5% CP, 3.6% Ca), hens were restricted to a maximum of 120 g feed/hen/day. Standard biosecurity measures and vaccination schedules were observed at the test centres. This study was approved by the International Livestock Research Institute Institutional Animal Care and Use Committee (ILRI IACUC) with reference number: IACUC-RC2016.26.

Discussion
The HES (70% and 68.2%) and HFE (83.2% and 83.7%) of both the foreign-sourced and locally sourced commercial hatchable eggs were similar. This suggests that apart from the genetics (Breeder flock and management), environmental factors such as proper storage and handling, general hatchery management, and appropriate incubator conditions are critical factors influencing hatchability of chicken eggs (Mauldin 2002). The HFE of all the breeds was within the range (52.4-87.0%) previously reported for both indigenous and cross-bred chickens (Alabi et al., 2012;Tadesse, 2014;Wondmeneh et al., 2011). However, only HFE of Fulani was lower than the range (80-90%) reported by MALDM (1993) for dual-purpose chicken breeds. The fertility and HFE of Fulani were low compared to the report by Adedeji et al. (2015) for Fulani chickens tested on-station (Fertility 85%, HFE 84%), but it was similar to that reported by Dunya et al. (2014) for Nigerian local chickens. The differences in the hatchability for Fulani may be associated with the variability within the Fulani population, since it is a localfarmer-developed strain (Olori 1992, Sonaiya 1998. At 42 days, Kuroiler, Noiler, and Sasso had better growth performance than FUNAAB Alpha and Shika-Brown when compared with Fulani. The bodyweight gain over Fulani Means with different superscripts on the same row were significantly different at p < 0.05, LSM least square mean, SEM standard error of the mean was 368%, 296%, and 245% in Noiler, Kuroiler, and Sasso, respectively, while it was 187% in FUNAAB Alpha, and 138% in Shika-Brown. Noiler was the most efficient at converting feed to live bodyweight with 50% reduction in FCR compared to Fulani. During the growing phase, Kuroiler (249%), Sasso (241%), and Noiler (211%) had higher mean live weights at 140 days for females, than FUNAAB Alpha (169%), Shika-Brown (138%), and Fulani (105%) when compared with the mean live weight (970 g) reported by Adedokun and Sonaiya (2002) for female Nigerian local chickens. At 140 days, the male live weights of the improved breeds were 304% (Sasso), 297% (Kuroiler), 267% (Noiler), 215% (FUNAAB Alpha), 173% (Shika-Brown), and 136% (Fulani) higher than the reported mean live weight (975 g) of male Nigerian local chickens raised on-station (Ajayi, 2010;Akinokun, 1975;Nwosu and Asuquo, 1984). This shows a cluster of fast (i.e. > 200% higher male live weights: Sasso, Kuroiler, Noiler, and FUNAAB Alpha) and slow (i.e. < 200% higher male live weights: Shika-Brown and Fulani) growing breeds, with Sasso and Kuroiler being the most efficient converters of feed to live weight.
The peak HDEP for all the breeds, except Sasso, was higher than the range (44.7-54.9%) previously reported by Adedokun and Sonaiya (2001) for Nigerian local chickens. Overall, the THI, at both Fol-Hope (30.5-30.4) and FUNAAB (30.8-31.1), was observed to plateau between the 8th and 9th months, when the peak HDEP (weeks 32-34) was recorded. This suggests that in addition to maintaining a normal (< 27.8) to moderate (27.8-28.8) THI-based stress indicator ranges, the relative stability of THI during rearing also enhances laying performance. Over 50% (10 months) of the total test period at FUNAAB were under severe to very severe (28.9-≥ 30) THI thresholds, as against a total of 7 months (39%) at Fol-Hope. The laying phase is accounted for 90% (9 months) of the entire months with the severe to very severe THI values at FUNAAB. The birds tested in the southern Guinea savanna (Fol-Hope) had lower feed per dozen eggs (3.5), and higher HHEP (142), and HDEP (62%) compared with the dry lowland rainforest (FUNAAB). This superior laying performance could be due to the moderate THI (28.8) compared with the severe THI at FUNAAB (29.4) because egg production decreases with increasing THI values and heat stress (Kilic and Simsek 2013;Mashaly et al. 2004;Sterling et al. 2003).
Overall, the locally sourced breeds had lower mortality rates (brooding 7.3%, growing 8.2%, and laying 20.5%) than the foreign-sourced breeds (Brooding 21.3%, growing 8.7%, and laying 24.2%) which suggests that the locally sourced breeds were more adaptable to the environment than the foreign breeds. High mortality rates are reportedly associated with weakened immune systems, resulting from high levels of temperature-induced stress and inability of animals to efficiently thermoregulate (Al-Awadi et al., 1995;Furlan and Macari 2002;Mashaly et al., 2004;Mumma et al., 2006;Perreira et al., 2010). According to Ajakaiye et al. (2011) and Tao and Xin (2003), high mortality, as influenced by heat stress, also depends on the physiological state and adaptability of the breed to its prevailing environmental conditions. In addition to THI, age and bodyweight are predisposing factors to high incidence of mortality in poultry (Perreira et al. 2010). Generally, across the two stations, mortality increased from day-old to the end-of-testing, at 504 days old. In this study, there was an increased  Fig. 1 Average temperature humidity index (THI) during the test period at the on-station centres mortality rate of female birds between the growing and laying phase for all the breeds, except Fulani. This may be due to the heavier bodyweight of the other breeds which presents a higher metabolic activity, and the challenge of maintaining adequate thermoregulation under heat stress (Furlan and Macari 2002;Lin et al. 2006). The low mortality observed during brooding for the locally sourced breeds, compared with the foreign breeds, suggests that the locally sourced breeds were more adaptable to the environment and could withstand the post-hatch stress and physiological changes accompanying early chick life (Yassin et al., 2009) better than the foreign breeds. Also, at the growing phase, females (6.0%) had a lower mean mortality rate than males (11.1%) which according to Leitner et al. (1989), may be associated with a generally less efficient immune response in male chickens.
The locally sourced breeds were more adapted than the foreign-sourced breeds. The breeds were differentiated into two clusters of faster-growing (Sasso, Kuroiler, Noiler, FUNAAB Alpha) and slower-growing (Shika-Brown, and Fulani) breeds. The faster-growing breeds had over 200% higher bodyweight compared with the local, unimproved chickens, while the HHEP of Shika-Brown, FUNAAB Alpha, and Noiler was over 200% higher than the local chickens. Based on the growth and laying performance, Noiler and FUNAAB Alpha were observed to have dual-purpose functions (i.e. for BW and egg production). On the other hand, both Kuroiler and Sasso were observed to have singlepurpose function for meat (BW), while Shika-Brown was most suitable for egg production. The overall ranking (i.e. highest to lowest) of the breeds across the rearing phases based on growth (Final live weight and FCR) and laying performance (Age at first egg, egg weight, HHEP, HDEP and feed/dozen eggs) and survivability is Shika-Brown, Noiler, Kuroiler, Sasso, FUNAAB Alpha, and Fulani.