Evaluation of fertility, hatchability and egg quality of indigenous chicken at different agro-ecologies of Sidama Region, Ethiopia

Poultry is one of the most important subsectors of livestock, supplying a cheap source of good quality animal protein in the form of meat and eggs. This study was conducted to assess egg fertility, hatchability and egg quality parameters of indigenous chickens in the Hulla, Aleta Wondo and Dale districts, representing highland, midland and lowland agroecologies, respectively. Six kebeles (two kebeles from each district) were purposively selected based on a lower distribution of exotic chickens. A total of 750 eggs of indigenous chicken were collected from three different agro-ecologies, 450 eggs were used for fertility and hatchability evaluation, and 300 eggs were used for internal and external quality analysis. The collected data were analyzed using SPSS version 20 and SAS version 9.0 packages. The results indicated that agroecology has no significant effect on the fertility and hatchability of indigenous chicken eggs. The values of egg weight, egg length, shell weight, yolk weight, and yolk diameter and albumen weight of eggs collected from midland were higher than those of eggs from highland and lowland areas. However, the highest values for albumen height, yolk height and Haugh unit were observed on eggs collected from highland agroecology. In conclusion, agroecology has no effect on the fertility and hatchability of indigenous chicken eggs. However, agroecology significantly affects the internal and external egg quality of indigenous chicken eggs. Therefore, the storage condition and duration of storage need consideration to maintain the external quality of eggs.


INTRODUCTION Background Information and Justification
Livestock is an important subsector of agriculture, and poultry is one of the most important subsectors of livestock, supplying a cheap source of good-quality animal protein in the form of meat and eggs (Nure Hasin, 2018). In Ethiopia, the term poultry is almost synonymous with chicken. Other poultry species, such as guinea fowl, geese, turkeys, and ducks, are not common in the country. Poultry production offers considerable opportunities in terms of generating employment opportunities, improving family nutrition, empowering women (especially in rural areas), and ultimately ensuring household food security. Extensive scavenging poultry production is often the domain of poor women. Reasons include that it requires little initial investment and that it does not usually conflict with women's other household duties (FAO, 2019).
Fertility and hatchability are major parameters of reproductive performance that are most sensitive to environmental and genetic influences (Stromberg, 1975). Fertility refers to the percentage of incubated eggs that are fertile, while hatchability is the percentage of fertile eggs that hatch. Egg quality is a factor that contributes to the better economic price of fertile and table eggs (Kocevski et al., 2011). The overall quality of an egg can be discussed under two broad categories, namely, external and internal quality (Monira et al., 2003). The external quality of the egg is determined by features such as the egg weight and shape of the egg, shell thickness, and strength of the shell (Bain, 2005). From the point of view of consumers, egg weight is the most important quality trait (Adeogun and Amole, 2004;Dudusola, 2010). Shell strength is important not only for producers but also for consumers. Obtaining high eggshell quality is important for both table egg and hatching egg purposes. Consumers have come to expect uniform, strong shelled eggs, and for hatching purposes, eggs that have a strong shell will be more likely to produce a healthy chick (Grignon 2016). The internal quality is measured based on the quality of the albumen as indicated by the Haugh units (HU), the relative size of the various internal components such as weight of yolk, yolk color and the integrity of the shell membrane.
Several studies have examined egg quality in chickens (Ahmedin and Mangistu 2016;Yonas et al., 2019;Aberra 2019;Welelaw 2018). In addition, the type of incubation influences the hatchability of eggs and the production of viable chicks. Most farmers in Ethiopia hatch their eggs by a natural incubation method using broody hens to incubate eggs and rear chicks (Meseret 2010 andAddisu et al., 2013).
Different studies have been performed on the egg quality, fertility and hatchability of local chickens. However, there is a lack of sufficient and consistent information on the effect of different agro-ecologies on the egg quality, fertility and hatchability of local chickens in the study areas. Thus, this study was conducted with the following objectives to fill the gap discussed.

Objectives
To evaluate the effect of agroecology on the fertility and hatchability of indigenous chickens in the Sidama region of Ethiopia To determine internal and external quality parameters of indigenous chicken eggs collected from different agro-ecologies of the study area

Description of study area
This study was conducted in three districts of the Sidama Regional State, namely, Hula, Aleta Wondo and Dale, representing high land, midland and lowland, respectively. Hula Hula District is located at a distance of 91 km from Hawassa and 366 km away from Addis Ababa. The district is located at longitudes and latitudes of 6°.41 '-6°.61'N and 38°.44'-38°.70'E, respectively, and l201 to 3000 masl elevation. It received a mean annual rainfall of 700-1200 mm with an average annual temperature of 11-180°C. The total population of the district is 80,464 (Hula district administration office, 2015). The total livestock population of Hula district is 15,456 cattle, 2,215 sheep, 1,056 goats, 769 horses, 456 donkeys, and 3,422 poultry (Hula district livestock and fishery office, 2019). The main agricultural activities of the district are livestock production, enset plantation and cereal crop production.

Aleta Wondo
Aleta wondo district is one of 36 districts in the Sidama Regional State. It is located at a distance of approximately 64 km from Hawassa and 339 km from the capital city Addis Ababa. It is situated in the coordinates of 60 35′ to 60 40′ north latitude and 380 25′ to 380 30′ east longitudes. Mean annual temperature ranging from 10 0 c to 24 0 c. Elevation ranging from 1700 to 2500 masl. The average annual rainfall of the district ranges from 900 mm to 1400 mm (Aleta agricultural practices in the areas include coffee plantations, inset plantations, maize and cereal crop production, cattle fattening, apiculture, vegetable production and fruit production.

Dale
Dale District is one of the 36 districts of the Sidama Regional State. The district is located on Hawassa to Moyale main road at 45 km from Hawassa and 320 km from the capital city Addis Ababa, and situated with latitude of 6° 39' 20''-6° 50' 28'' North and longitude of 38°18'12'' -39°31'30'' East. Its elevation ranges from 1200-3200 masl. The annual rainfall of the Dale district ranges from 1300-1900 mm, and the annual temperature varies from 180°C to 20°C (DWARDO, 2015). The main agricultural activity of the district is livestock production, enset plantation, coffee plantation and cereal crop production.

Protocol of the experiment
The experiment had two parts. The first part was fertility and hatchability evaluation. For this test, farmers who owned at least one cock of local chicken in his flock were selected during survey work. From those selected households, one hundred fifty eggs of local chickens were collected from each agroecology and transported to Hawassa University Agricultural College, School of Animal and Range Sciences. Eggs were individually cleaned using pieces of clothes treated with savlon before setting. Incubation was conducted according to the guidelines of the incubator's manufacturer. Then, candling was performed two times (day seven and day fourteen). Data on the number of eggs set, number of eggs that were fertile, total number of chicks hatched, and number of embryos that died were recorded. The second part was internal and external egg quality evaluation. This study was conducted at Hawassa University Agricultural College, School of Animal and Range Sciences, poultry laboratory. One hundred eggs were collected from each agroecology (a total of three hundred eggs were used for internal and external quality evaluation). Care has been given that eggs collected should be laid from local chicken breeds (eggs collected from farmers who own only local chickens). The eggs stored for less than five days were collected, and laboratory analysis was conducted as soon as the eggs reached the laboratory.

External egg quality traits
Egg weight and shell weight were measured using a digital balance (gm). Egg length, egg width and shell thickness were measured using a digital caliper (mm). Shell weight was measured after it was dried in an oven for 24 hours (Khatkar et al., 1994). The shell thickness was measured using digital calipers at different points (center, broad and narrow ends), and the calculated average value was used for analysis (Mohammed et al., 2005). In addition, the eggshell ratio and egg shape index were computed using the following formula.

Internal Egg Quality
For the internal quality traits, the eggs were broken into a flat surface. Thick albumen and yolk heights were measured using a tripod micrometer. The thick albumen height (AH) was measured at its widest part at a position half way between the yolk and the outer margin. Yolk height was measured at the center part of yolk. The yolk was carefully separated from the albumen.
Albumen and yolk weights were determined by weighing with an electronic sensitive balance separately (gm). The yolk color was determined using the Roche Color Fan (Roach scale), which contains 15 scales with a standard colorimetric system. Individual Haugh units (HU) were calculated from the two parameters height of albumen (AH) and egg weight (EW) (Haugh, 1937) using the formula.
Estimate YR and AR were used the following formula: *100

Statistical analysis
The laboratory data for fertility and hatchability were analyzed by crosstabs among agroecologies in descriptive statistics of SPSS V.20.0. Other parameters, such as external and internal egg quality and correlations among egg quality parameters, were analyzed using the general linear model (GLM) procedure of SAS (Version 9.0). Mean comparisons were conducted using Duncan's multiple range test. Values were considered significant at the 5% level of significance.

Fertility and hatchability
The fertility and hatchability results of scavenging indigenous chickens are shown in Table 1.
There was no significant variation among agro-ecologies in the egg fertility percentage of indigenous chickens. This implies that agroecology has no influence on the fertility of scavenging indigenous chicken eggs. The result in the current study is in line with the study by Ahmedin and Mangistu (2016), who reported a fertility of 74.45% on rural chickens in the Gorogutu district of Eastern Hararghe. A higher value of fertility (81.1%-100%) was reported by Halima (2007) in different agro-ecologies of Northwest Ethiopia, and 95.6% and 98.9% was reported by Getnet et al. (2020) on eggs of Tilil and unimproved Horro chickens reared under intensive management. The highest value obtained might be observed due to the variation in the production system. The fertility percentage of indigenous chicken eggs in the current study was higher than the values reported by Meseret (2010) in the Gomma district of the Jimma Zone. The result on hatchability percentage in the current study is in agreement with the report by Mbuthia et al. (2007), who reported that 82.8% hatchability was recorded for indigenous chickens in Kenya.
There was no significant difference in hatchability on the total egg basis of indigenous chicken eggs among all studied agro-ecologies (p>0.05). The result on hatchability percentage (63.1%) in the current study is in agreement with the findings of Tadelle (2003) and Ahmedin and Mangistu (2016), who reported 68.8% and 64.45%, respectively, with no significant difference in hatchability percentage of Ethiopian indigenous chicken in different agro-ecologies. The finding of the current study is in agreement with the range given by Halima (2007), who reported hatchability of indigenous chickens between 46.2% and 73.3%. The finding of the present study is lower than the result of Gebreegziabher (2016), who reported total egg basis hatchability of 83.6% in the highlands and 74.1% in the midland agroecology of the Wolaita Zone.
The results of the current study revealed that agroecology has no impact on hatchability on the fertile egg basis of indigenous chicken eggs (p>0.05). In agreement with current findings, Getnet

External egg quality traits
The external egg quality traits in different agro-ecologies are presented in Table 2. The results indicated that values for egg weight and egg length in midland were significantly higher than lowland and highland, whereas values of egg weight and length in highland is lower than values lowland agro-ecology. Egg weight is highly influenced by hereditary and environmental factors (Sekeroglu & Altuntas 2009). Environmental factors in terms of the age of hens, body size, diet, water intake, temperature, humidity and management practices may contribute to the variability observed in the results (Isidahomen et al., 2013). The result on egg weight and length in the current study is in agreement with the finding of Aberra (2018) The results indicated that agroecology in the study areas had no effect on the shape index of indigenous chicken eggs (p>0.05). In agreement with the current study, Aberra (2018)  reported an average shape index value of 80.40 on indigenous chickens of Pakistan, which is much higher than the result of current findings. Nedeljka and Kocevski (2006) suggested that the shape index is influenced by season, genetic factors and age group of birds. Eggs are categorized into three shape groups: Sharp (<72), normal (72-76) and round (>76). As this classification, the results of the current study show that eggs of indigenous chickens are classified as normal eggs regardless of other factors. The shape index is an important factor for characterizing species of birds (Song et al., 2000), as well as an indicator of egg quality (Mueller, et al., 1960) and is very important for chick survival (Lundberg and Vaisanen 1979). Egg shape is an important parameter in commercial systems. Sharp eggs and round eggs do not fit well in egg cartons; therefore, they are much more likely to be broken during shipment than eggs of normal shape (Sarica and Erensayin, 2009).
The study indicated that agroecology has a significant effect on the shell weight of indigenous chicken eggs (p<0.05). Accordingly, shell weight is highest (4.38 gm) in midland agroecology and lowest (3.70 gm) in highland agroecology. In agreement with the present study, shell weights within the range between 4.02 gm and 4.88 gm were recorded by Halima (2007)  accepted as being better in more successful hatching of embryos, especially from larger eggs (Narushin and Romanov, 2002).
There was a significant effect of agroecology on the shell percent of indigenous chicken eggs (p<0.05). It is highest in lowland agroecology but lowest in highland agroecology in the study areas. Demissu (2020) reported a higher shell percent on unimproved Horro chickens in all agroecologies than the results of the current study.

Internal egg quality traits
Internal egg quality traits at different agro-ecologies are presented in Table 14. There was a significant difference in the yolk height of indigenous chickens in different agroecology systems (p<0.05). Yolk highest is highest in highland agroecology and lowest in lowland agroecology.
The conducted. Thus, albumen height is an indication of the freshness of eggs (Zeidler, 2002).
Significantly higher yolk weight was recorded in midland agroecology than in highland and lowland agroecology, but yolk weight was the same in both highland and lowland agroecology of the region. Halima (2007) and Demissu (2020) reported lower results, but Meseret (2010), Welelaw et al. (2018) and Ahmedin and Mangistu (2016) reported nearly similar results to those of the current study. The mean yolk weight value of 15.13 grams was recorded from a study conducted on Indigenous Sakini Chicken of Nepal (Saroj et al., 2020). A much lower yolk weight value of 9.667 grams was reported by the study of Nuhu et al. (2018) conducted on Nigerian indigenous chicken ecotypes. This difference can occur due to differences in genes and the environment.
Albumen weight shows significantly different values between all agro-ecologies. The highest albumen weight was measured midland, followed by lowland, and the lowest albumen weight was recorded in highland agroecology. Similarly, Halima (2007)  There was no significant difference in yolk color, albumen ratio or yolk ratio among the different agro-ecologies of the region. The yolk color results in the current study are in agreement with the reports of Meseret (2010) and Yonas (2019). However, a lower result was revealed by Halima (2007), who reported Roch fan results between 3.00 and 4.00 for different indigenous chicken ecotypes under intensive management conditions. This implies that the difference in the production system has a high impact on the yolk color of eggs from indigenous chickens. The color of the egg yolk is mainly dependent on the type of ration and the management systems of the chickens. The eggs collected from scavenging birds have a higher yolk color count because scavenging birds have free access to green plants and other feed sources rich in xanthophylls (Zaman et al., 2004). According to a study conducted in Boricha District, the sidama regional state breed and agroecology showed significant differences in yolk color (Aberra et al., 2019).
The value of yolk color is higher for indigenous chickens than for exotic chicken breeds. This might be due to indigenous chickens having a better scavenging ability to obtain greenish scavengeable feed resources that contain high amounts of xanthophylls. In agreement with the current study, Demissu (2020) reported 54.71% and 34.99% average albumin ratio and yolk ratio, respectively. A higher albumen ratio (75.373) and lower yolk ratio (26.747) were recorded in Nigerian indigenous chickens (Nuhu et al., 2018) The Haugh unit and yolk index are significantly highest in the highland agroecology and lowest in the midland agroecology. A lower value of the Haugh unit was given by Welelaw et al. (2018), Halima (2007) and Meseret (2010), but a nearly similar result was reported by Yonas (2019) (Nuhu et al., 2018).
There were differences in the yolk diameter of indigenous chickens among all agro-ecologies of the Sidama region. Yolk diameter is highest in midland followed by lowland and lowest in highland agroecology. In agreement with the current study, Demissu (2020)

Phenotypic correlation among external egg quality traits
The phenotypic correlation of the external egg quality traits of indigenous chicken eggs is presented in Table  No significant positive correlation was reported between egg length and shell weight or between egg width and shell weight in three different strains of Tswanan chickens (Kgwatalala et al., 2016). Egg length is highly negatively correlated with the shape index, but egg width and shape index are strongly positively correlated with each other. This indicates that when the egg becomes wider, its shape index will be larger, and it will possess a round shape that makes it difficult to handle and package. Similarly, a strong negative correlation between egg length and shape index and a strong positive correlation between egg width and shape index were shown in dwarf, normal and necked neck indigenous chickens of Tswana (Kgwatalala et al., 2016).
Shell weight has a strong positive correlation with shell percentage and egg surface area. Sezai et al. (2015), Markos et al. (2017) and Islam and Dutta (2011) reported a significant positive correlation between shell weight and shell ratio in different poultry species. Shell percentage is defined as the ratio of shell weight to total egg weight, so that the amount of shell weight increases then higher will be shell percentage.
Shell percentage has a strong negative correlation with egg weight and surface area. In agreement with the current study, Bertha (2013) reported a significant negative correlation between shell ratio and egg weight on Cobb 500 broiler hatching eggs. However, the report of Olawumi and Ogunlade (2008) is the reverse of the current study; they reported a nonsignificant positive correlation between shell ratio and egg weight in exotic Isa brown layer breeders.
Additionally, there was a nonsignificant negative correlation between shell percentage and egg length and between shell percentage and egg width. This result is in agreement with the results of Sezai et al. (2015) and Markos et al. (2017).

Phenotypic correlation among internal egg quality traits
The phenotypic correlations among internal egg quality traits are shown in Table 5. The results indicated that there was a strong and positive correlation between albumen weight and yolk weight and between albumen weight and yolk diameter. This result disagrees with the result of Bertha (2013), who reported that there is a negative correlation between albumen weight and yolk weight and yolk diameter. Markos et al. (2017) reported a strong positive correlation between albumen weight and yolk weight in highland midland and lowland ecotypes of Tigray chickens. A strong positive correlation between albumen weight and yolk weight was reported in dwarf, normal and necked neck indigenous chickens of Tswana (Kgwatalala et al., 2016). This result is in agreement with the findings of the current study.
Albumen height is strongly positively correlated with the Haugh unit. In agreement with the current study, Bobbo et al. (2013) (2013) and Olawumi and Ogunlade (2008). However, a nonsignificant negative correlation was reported between albumen height and yolk height for local barred hens of Cameroon (Mube et al., 2014). However, there was a strong negative correlation between albumen height and yolk diameter. Bobbo et al. (2013) reported a strong positive correlation between albumen height and yolk height for necked neck indigenous chickens, but in a similar study, he reported a negative nonsignificant correlation between albumen weight and yolk weight for frizzle and smooth feathered indigenous chickens of Yola. These differences in egg qualities might occur due to different factors, such as storage, strain and age of hens, induced molt, nutrition and disease (Roberts. 2004).
Yolk weight was positively correlated with yolk diameter and strongly negatively correlated with the yolk index. This implies that as yolk weight increases, yolk diameter also increases. This result is consistent with the report of Markos et al. (2017). However, the results of the current study disagree with the findings of Okon et al. (2020), who reported a value of -0.296 between yolk weight and yolk diameter. Additionally, there was a negative correlation between yolk weight and Haugh units. This result agrees with the reports of Olawumi and Ogunlade (2008) and Bertha (2013).
There was a strong positive correlation between yolk height and Haugh units. Different scholars have reported similar findings to the current study (Markos et al., 2017, Olawumi and Ogunlade 2008and Bertha 2013. This implies that yolk height and albumen height go in the parallel direction. When we opened the egg during our study, the first indications of its quality were both albumen height and yolk height. If the egg was stored for a long time, albumen and yolk expanded suddenly as the egg was opened, then measurements of both albumen height and yolk height decreased. Yolk diameter is strongly negatively correlated with the yolk index and Haugh unit. Sezai et al. (2015) reported that yolk diameter has a strong negative correlation with the yolk index and a nonsignificant negative correlation with the Haugh unit. This might occur because when yolk height decreases due to different factors, yolk expands, and its diameter increases. The yolk index and Haugh unit are strongly positively correlated with each other. This result is in agreement with findings reported by Ojedapo (2013) and Bobbo et al. (2013). These two parameters are related to yolk height and albumen height. As discussed above, when albumen height decreases due to different factors, yolk height also decreases, and the same is true for the yolk index and Haugh unit. Haugh unit -0.12347 * 0.96261 ** -0.18928 ** 0.52967 ** -0.28406 ** 0.51693 ** 1 *:p<0.05, **:p<0.01

Phenotypic correlations between some internal and external egg quality traits
Phenotypic correlations between external and internal egg quality traits are presented in Table 6.
The results of the current study show that albumen height has a statistically significant negative correlation with egg weight, egg length, egg width and shell weight (p<0.01). In agreement with the current study, Bertha (2013) reported a significant negative correlation of albumen height with egg weight, egg length, egg width and shell weight. There was a slight positive correlation between albumen height and shell thickness (p>0.05). Godson et al. (2020) found a positive correlation between albumen height and shell thickness. This implies that albumen height can be affected by shell strength because a thicker shell has better resistance to temperature and can control the entry of microorganisms inside the egg. Then, albumen height remained high for a longer time than eggs with thinner shells.
The correlation of albumen weight with egg weight, egg length, egg width and shell weight was positive and statistically significant (p<0.01). These findings were supported by Olawumi and Ogunlade (2008), Bertha (2013), Kul and Seker (2004), and Markos et al. (2017). Albumen weight was significantly and negatively correlated with shell thickness (p>0.05). This result is in agreement with the findings of Kul and Seker (2004). There was a statistically nonsignificant positive correlation between albumen weight and shape index (p>0.05). This finding was supported by Sezai et al., (2013). However, disagreement was reported on scavenging indigenous chickens of Zambia by Rifu et al. (2020), who reported a strong negative correlation between albumen weight and shape index.
Haugh unit had a strong negative correlation with egg weight, egg length, egg width and shell weight (p<0.01). This happened due to the strong negative correlation of albumen height with these parameters. This result disagrees with the findings of Kul and Seker (2004) and (Bertha 2013). In agreement with the current study, the findings of Alipanah et al. (2013) and Godson et al. (2020) revealed that there is a strong negative correlation between the Haugh unit and shell weight of eggs.
Yolk height had a negative but nonsignificant correlation with external egg quality parameters that were observed in this study (p>0.05). Godson et al. (2020) reported a positive correlation of yolk height with egg weight, egg length and egg width. In a similar study, he reported a negative correlation of yolk height with shell weight, shell thickness and shape index, which is in parallel with the findings of the current study. In contrast to the findings of the current study, Bertha (2013) found a strong positive correlation of yolk height with egg weight, egg length, egg width and shell weight of Cobb500 broiler hatching eggs.
Yolk diameter had a strong positive correlation with egg weight, egg length, egg width and shell weight (p<0.01). This result is in agreement with the findings of Kul and Seker (2004) and Rifu et al. (2020). However, there was a slight negative correlation of yolk diameter with shell thickness and shape index (p>0.05).
Yolk weight had a strong positive correlation with egg weight, egg length and egg width (p<0.01). This result was supported by Kul and Seker (2004), Markos et al. (2017), and Rifu et al. (2020). According to these findings, including the current study, yolk weight increases with increasing external parameters. Egg weight, length and width increase with different factors, such as the age of the hen, breed and strain, nutrition and other environmental factors. At the same time, the weight of the egg increased.
The yolk index had a significant negative correlation with egg weight, egg length, egg width and shell weight (p<0.01). This result disagrees with the findings of Rifu et al. (2020) andBertha (2013). There was a slight positive correlation between the yolk index and shell thickness and the shape index (p>0.05). In line with the present study, Godson et al. (2020) showed a slight positive correlation between the yolk index and shell thickness. The finding of Rifu et al. (2020) agrees with the results of the current study on the correlation between the yolk index and shape index.

Conclusion
The results show that agroecology has no effect on the fertility and hatchability of indigenous chickens. Eggs collected from midland agroecology had the highest egg weight, egg length, egg width and shell weight, followed by those collected from lowland agroecology. However, agroecology has no effect on the shape index of indigenous chicken eggs. Eggs collected from midland showed superior yolk weight, albumen weight and yolk diameter. However, eggs collected from highlands showed the highest yolk height, albumen height, yolk index and Haugh unit values. Agroecology has no effect on the yolk color of indigenous chicken eggs. Therefore, it can be concluded that midland agroecology is more favorable for external and internal egg quality of indigenous chickens when stored for a short period of time, but eggs remain fresh for a longer time in highland agroecology.

References
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