Evaluation of options for improving hatchability in indigenous free-range chickens in Eastern Uganda

H Kirunda and N Muwereza*

* National Livestock Resources Research Institute (NaLIRRI),
PO Box 96, Tororo, Uganda
halidkirunda@gmail.com

Abstract

Different options for improving hatchability in indigenous free-range chickens were evaluated. The aim was to establish alternatives that could increase mean hatchability to more than 80% as previously reported in village chickens in other countries. A total of 1,182 hens were recruited. Farmers were required to provide water and feed provision at nest, turn eggs in the nest and monitor hens for any mite infestation. Independent variables were site of egg storage, type of nest material, number of eggs provided to hen to incubate and hen-cockerel relationship. The study response variable was hatchability proportions. Data on these parameters were captured. Quantitative data were analyzed by SPSS for descriptive statistics and determination of significance of relationships done using Kruskal-Wallis Test (p=0.05).

There was a significant relationship (p<0.05) between hatchability and site of egg storage; nest material used; number of eggs incubated; and the relationship between parent hen and cock.  Hens incubating egg stored on trays, using cotton as nest material, incubating 12-14 eggs and mated to unrelated cockerel had frequencies of  >80% mean hatchability in at least 55.0%, 57.9%, 58.5% and 57.3% of the study hens, respectively. In addition to provision of water and feed at nest and turning eggs at least four times a day, farmers should be encouraged to use egg trays for storage, use of cotton, straw or sawdust as nest material, provide only 12-14 eggs and mate hens only to unrelated cocks if hatchability is to be increased to> 80% among free-range chickens in Eastern Uganda.

Key words: Egg site storage, feed and water supplement, nest material, number of incubated eggs

Introduction

In Uganda hatchability among free-range chickens had been reported to range from 70.8% and 85.7% (Illango et al 1999) and 45-75% (Byarugaba et al 2002). Whereas hatchability of 80% (of eggs set) from natural incubation is normal or a range of 75 to 80% is considered satisfactory (Sonaiya and Swan 2004) higher hatchability proportions had also been reported among village chickens in other studies in other countries (Wilson 1979; Kusina et al 1999; Moges et al 2010). A mean hatchability in the range of 80.4% in dry season to 89.3% in the wet had equally been observed in a more recent study in Eastern Uganda (Kirunda et al 2010).  

Several factors have been reported to affect hatchability of eggs and, among others, they include season of lay, disease, nutrition, chicken age, egg quality, genetic factors, hygiene and incubation conditions in the nests, (Horst 1988; Austic, et al 1990; Sainsbury 1992; Ojok 1993; Walsh et al 1995; Kabilika et al 1999; Danilov 2000; Kirunda et al 2010). Incubation conditions mainly include temperature, humidity, ventilation, position, and turning of the eggs (Wilson 2004; Tona et al 2003). It is required that eggs are turned at least 3-6 times daily during the incubation period (http://www.sabong.net.ph/forum/) in order to enhance higher hatchability proportions. Proportion of up to 72.9% was achieved when eggs were turned at least thrice a day (Abiola et al 2008). In addition, eggs initially need a very controlled heat input to maintain the optimum temperature of about 38°C and  moisture levels of 60 to 80% of relative humidity for appropriate embryonic development (Sonaiya and Swan 2004). To ensure that appropriate warmth is maintained under natural incubation, straw, rice hulls and sawdust (Shahvali et al 2000) are among the nest materials that have been tried. Under natural incubation, an optimum number of eggs should be given to a hen. While up to 20 eggs have at times been given to hens to incubate (Shahvali et al 2000), a maximum of 14 to 16 eggs may be brooded in one nest because hatchability has often been observed to decline with more than ten eggs (Sonaiya and Swan 2004).  

This study was undertaken to evaluate options for improving hatchability in indigenous chickens in Eastern Uganda. It was conducted based on findings of an earlier study (Kirunda et al 2010), which revealed a significant variation in hatchability among hens incubating on different nest materials in the region.  

Methods and Materials

Study area  

Study area included sub-counties in the banana-coffee and banana-millet-cotton farming systems - agro-ecological zones in Uganda (Mwebaze 2006). The districts of Iganga and Kamuli were purposively selected because they are among the areas with the highest density of local chickens in Uganda (UBOS/ILRI 2002). The sub-counties of Irongo, Nawandala and Nabitende in Iganga district and Namwendwa and Nawanyago of Kamuli district were selected. A total of eight villages; four in Iganga and four in Kamuli were used, with each participating in the evaluation of the four study parameters.  

Sample size 

Since the study was a single-group experiment for continuous variable, sample size was determined using the equation described by Snedecor and Cochran (1989);

where s = the estimated population standard deviation of hatchability of 15 - based on the mean hatchability of Uganda of 60% (45% - 75%) reported in a recent study by Byarugaba et al (2002) and d = the difference between 75% (Byarugaba et al 2002) and 77% mean hatchability regarded satisfactory under natural incubation (Sonaiya and Swan 2004). Substituting 15 for s and 2 for d, and computing for n, sample size of 1182 was adopted and therefore was 1182 hens recruited for the study.  

Study design  

Hens previously vaccinated against Newcastle disease were recruited from households where laying hens were found and in which farmers were ready to provide at least one of the nest materials under study. Laying hens were recruited and farmers in the study households asked to collect the laid egg from each of the nests of the selected hen. Egg collection was done on a daily basis and eggs of a given hen stored in specified site. For ease of determination of the date on which an egg was laid, eggs of each hen were individually labeled before being stored. Storage sites included: on the floor, on cotton wool, inside box/basket, on sand or ash, on coffee husks, on egg trays in pots, on sawdust. As another storage site farmers were asked to just leave eggs on the nest. No temperature recording or monitoring was done for any of the study storage sites. When a hen appeared to have stopped accumulated eggs were after selection given to the hen to incubate. Eggs were selected starting with the egg laid last in the clutch, that is, in a reverse order. The incubated eggs were therefore aged day 1 to a maximum of 15 days. Hens were grouped into four categories depending on the nest materials used in the nest. One of four different types of materials was used for each incubating hen. The material included cotton, ash, sand and straw/sawdust. Each hen was provided with 10, 11, 12, 13, 14 or 15 eggs to brood, but no temperature recordings were taken for any of the nest materials used. Each farmer was asked to ensure that the brooding hen was provided with water and feed supplements (Sonaiya and Swan 2004) at the nest and its eggs turned four times each day for at least 18 days. Mites were controlled in the study households. Records about the relationship between each recruited hen and its mating cock were taken. 

Data collection and analysis

A record card was used to capture data on the different study parameters. Parameters (independent variables) included egg storage site, nest material used, number of eggs provided for incubation and the relationship between the hen and cock. The other parameter (dependent variable) on which data was captured was number of eggs hatched, from which the hatchability percentages per hen were computed. Quantitative data were entered into and analysis made using Statistical Program for Social Scientists (SPSS) version 12.0 for Windows. Analysis was done by descriptive statistics and determination of significance of relationships for response variables made using a non-parametric test for independent samples, Kruskal-Wallis Test (p=0.05). The data were also imported into and figures drawn by Microsoft Excel program. 

Results

Effect of site of egg storage on hatchability 

Results of evaluation of options of sites of egg storage are shown in Table 1. The study observed that there was a significant effect (p<0.05) between the site of storage and the proportion of egg hatched by hens on free-range management system. Out of the 218 that incubated eggs previously stored on egg trays, up to 96.8% of them had beyond 80% hatchability. This was followed by hens that incubated eggs stored on cotton wool (88.6%, n=88), in a pot (84.8%, n=46), on the floor (68.4%, n=19), in a box/basket (61.3%, n=119), left on the nest (44.5%, n=501) and stored on sawdust (42.9%, n=14). Among the study hens that achieved >80% hatchability only 4.3% (n=114) and 3.1% (n=63), respectively, incubated eggs previously stored on sand/ash and on coffee husks.

Effect of nest materials on hatchability 

Material used on the nest caused variation in hatchability with results revealing significant effect (p<0.05) between nest material used in the nest and the percent hatchability achieved per study hen. Among the four materials evaluated, the highest hatchability percentage was achieved with cotton. Of the 311 hens that incubated on cotton, 242 (77.8%) of them had their hatchability surpass 80%. This was followed by hens that incubated on ash (55.5%, n=292) and sawdust/straw (52.5%, n=284). Only 44.4% (n=295) of hens that incubated on sand exceeded 80% level of hatchability. The hatchability proportions of hens based on types of nest materials are shown in Fig.1. Deducing from the trend shown in the results, the performance of ash was not consistent.   

Figure 1. Numbers of hens achieving hatchability (%) ranges with different nest materials

Effect of number of eggs incubated on hatchability 

Effect of number of eggs incubated and hatchability levels were statistically significant (p<0.05) among the study hens. Table 2 presents the frequency and percentages of hens that achieved hatchability proportions exceeding 80% with the different numbers of eggs incubated during the study period. Up to 216 hens (91.5%) of the 236 hens that incubated 13 eggs achieved hatchability proportions of >80%. Additionally, as many as 223 (84.8%) and 126 (62.1%) of hens that incubated 12 and 14 eggs, respectively, equally achieved hatchability rates beyond 80% while 58.5% (n=120) and 45.5% (45.5%) among those that incubated 11 and 10 eggs managed to achieve this level of hatchability.

The smallest proportion (25.0%, n=72) of hens to get >80% hatchability were those which sat on 15 eggs. Regardless of the number of eggs incubated, the lowest hatchability proportional range recorded was 41-50%, which was exhibited by only 0.05% of the 1,182 study hens (results not shown) and this was mainly among hens that incubated on ash.  

Effect of parental relationship on hatchability 

Numerical variation in hatchability was observed among hens that laid and incubated eggs having been mated to cocks with which such hens shared some genetic relationships. The effect of hen-cock (parents) relationship on hatchability was significant (p<0.05). Hatchability proportions beyond 80% were mostly (66.1%, n=917) achieved among hens that did not have any form of genetic relationship with their mating cocks (Table 3).

Smaller proportions of hens that had relationships with their mating cocks achieved hatchability percentage of more than 80%. Among hens that were mated to cocks with which they had a breeding relationship, the biggest proportion of hens to achieve >80% hatchability was among hens that were mated with cocks which were sons. The proportion among this group that achieved hatchability of the study target only 43.1%. This was followed by only 27.9% and 20.0% of hens were mated to brother and grandson-related cocks, respectively. Hens bred to cocks that had a father or grandfather relationship had the lowest proportion of hens to achieve hatchability percentage exceeding 80% and the respective proportions of such hen categories were only 16.7% and 16.0%.        

Discussion

In this study the hatchability proportions ranged from 45 - 100%, with mean hatchability of 81.5%. Regardless of the parameter of study, at least 57.3% out of the 1,182 hens achieved hatchability proportions that exceeded 80%. The range of hatchability reported in this study is similar to 50-100% reported in United Republic of Tanzania (Minga et al 1989), 60-90% in Burkina Faso (Bourzat and Saunders 1990) and 60-95% in Senegal (Gueye 2003). While the study hatchability range was higher than 70.8-85.7% (Illango et al 1999) and 45-75% (Byarugaba et al 2002) reported in earlier studies in Uganda and 70.1-78.3% in Nigeria (Sola-Oja 2011), it was lower than 70-100% reported in other studies (Fayeye et al 2005; Alaba 1990; Atteh 1990). Mean hatchability of this study was higher than 80.9% (Tadelle and Ogle 1996) in Ethiopia; 69.7% (Eugene 2004) in Philippines, 78% (Khalafalla 2000) in Sudan and Nharira (69%) and Lancashire (74%) in Zimbabwe (Maphosa et al 2004) despite the fact that it was lower than  90% hatchability of village chickens in Sudan (Wilson 1979), 82% in communal area of Zambabwe (Kusina et al 2000), 81.7% in Ethiopia (Moges et al 2010) and 84.9% hatchability reported in a study in Uganda (Kirunda et al 2010). The probable reasons for lower mean hatchability resulting from this study are, among other, the longer time storage of eggs and possible bacterial contamination from the storage sites and nest materials that were locally solicited and non-sterilized. In our study most of the eggs were stored beyond four days with some of them being stored for up to 15 days. Storage for only four days (Decuypere and Michels 1992; Schmidt et al 2009) is most recommended, although under natural incubation egg storage may be extended to maximum of 14 days (Elibol and Brake 2008). Contamination of eggs by bacteria from the environment has been reported in several countries (Kibikika et al 1999; Siddiqui et al 2008; Nemati et al 2008) including Uganda (Kirunda et al 2010).  

Whereas tray egg storage resulted in higher hatchability proportions, proportionately lower hatchability was with other storage sites. The variation in hatchability proportions could easily be attributed to site of egg storage. The storage site effect could be strengthened by the fact that all eggs used in the study were from hens vaccinated against Newcastle disease (the most prevalent disease) and were selected against cracks, infertility, shape deformity, improper shell thickness and for inappropriate size. Since the egg and host factors that affect hatchability had been minimized, it is mainly the storage site factors that could therefore have significant influence on hatchability. Several factor such as site temperature, humidity and hygiene affect hatchability (Austic et al 1990; Sainsbury 1992; Brake et al 1997; Kabilika et al 1999; Danilov R V 2000; Ruiz and Lunam 2002; Samli et al 2005). 

In this study a significant deviation in percent hatchability was observed with sand and coffee husks. Whereas storage in sand has occasionally been recommended (Olsen and Clubb 1997), in this study on-sand egg storage was investigated. Therefore, sand surface temperature, appears to have had a greater influence than the temperature inside the sand bed. Sand has been described to be a good heat absorber. It can be warm in the day though may be cooler at night (Weeks 2003); sand particles exposed to heat will get pretty warm or hot, pretty fast. Although sand gets much cooler a few centimetres down, the surface of the same sand can concomitantly be warm (Week 2003). Since dry sand is known to be poor at heat transfer, it is possible that sand maintains warmth on its surface for longer hour into the night and hence subjecting the eggs to warm temperatures for longer hours. Sand surface temperature, just as the temperature on the surface of the coffee husks could greatly be influenced by the environmental and room temperature in houses of egg storage. In Uganda, environmental temperature range is 25^oC-30^oC while the average room temperature during day time is 25^oC and relative humidity of 70-100% (Nshemereirwe 2004; PATH 2010). Night temperature, in the study area may however frequently be cooler (about 18^oC). Whereas Uganda’s room temperature is within the normal range of the physiological zero (27^oC) - the temperature that must not be exceeded during egg storage (Walsh et al 1995) - for increased hatchability, eggs should optimally be stored at 12.7°C and 65-85% relative humidity (Parker and Parker 1969; Anderson 1979) or 12.8-18.3°C and 75% relative humidity (Walsh et al 1995; Olsen and Clubb 1997) in a clean egg tray or in sterilized sand. Since literature on use of coffee husks as a storage material is largely lacking discussion of effect of sand could not be readily discussed. The possible bacterial contamination, which could have occurred to eggs stored on sand and coffee husks may partly be used to explain the lower hatchability since these two materials were not sterilized when used in this study.  

A significant relationship between the nest materials used and hatchability was observed. This could be attributed to the difference in the ability of different materials to maintain warmth. Whereas some materials used by farmers of Eastern Uganda are good at maintaining warmth, others could be relatively poor. The good hatchability proportion reported of cotton, straw and sawdust in this study could be due to the ability of these materials to maintain warm and the reason for promotion of their use by farmers in some countries (Shahvali et al 2000). Much as hens incubating from ash showed fair proportions of hatchability, its trend in influencing this was not clear. Since no literature was readily available on the use of ash as a nest material, the effect of ash on hatchability could not be adequately discussed.  

The best hatchability proportions were shown by hens that incubated 12-14 eggs and the worst rates were among hens that sat on 15 eggs. This was consistent with a study by Moges et al (2010) in which hatchability proportion of 84 – 86% was reported among hens that incubated 13-14 eggs in Ethiopia and Sonaiya and Swan (2004) who indicated that a maximum of 14 to 16 eggs could be brooded in one nest. Results of our study continued to confirm that hatchability often declines with more than ten eggs (Sonaiya and Swan 2004). The size of hens in the two farming systems of study is about 1.5 kg live weight, which is of medium size among indigenous hens in Uganda (Ssewannyana et al 2003). Such hens can easily sit and cover between 12 and 14 medium size eggs (50-55g) (Sonaiya and Swan 2004) but may not be able to do so with eggs beyond that number.  
 

Variation in hatchability among hens that laid and incubated eggs having been mated to cocks with which such hens shared some genetic relationships was observed in our study. This could be attributed to genetic factors. Like revealed decades ago (John and Merritt 1955; Washburn 1990) and in recent years (Szwaczkowski et al 2003), our study equally observed lower hatchability proportions among hens that were mated to closely related cocks. The closer the relationship the lower the hatchability, the study was revealed. 

Conclusion and recommendations

• This study has proved that with proper positioning of local eggs (big side up) during eggs storage on trays; use of cotton, straw and sawdust; provision of only 12-14 eggs for hens to incubate and using eggs only from hens mated to unrelated cocks, hatchability among free-range chickens can exceed 80%.

  
  

• Proper egg handling and nest hygiene, provision of water and feed, as well as, external parasite control and vaccination against Newcastle diseases and infectious bronchitis must be emphasized, if the four studied factors are to enhance hatchability among indigenous chickens on free-range management system.  

Acknowledgements

We are grateful to farmers and staff of veterinary department and NAADS Programme in Iganga and Kamuli districts.  Thanks are also extended to National Agricultural Research Organisation (NARO) for Project Coordination, and Government of Uganda and World Bank for funding the study. 

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Received 26 April 2011; Accepted 15 August 2011; Published 1 September 2011

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