Effects of Season on Disease Frequency and Mortality of Poultry in Owerri Urban South-Eastern Nigeria

The study examined effects seasons have on diseases frequency and mortality of poultry birds in Owerri urban south-eastern Nigeria. The study therefore employed the use of secondary and primary data. Climatological data on rainfall, temperature, relative humidity and mortality of birds was collected from Nimet, Sam Mbakwe International cargo Airport, Imo State and ministry of livestock development Owerri respectively for a period of 16 years (2004-2019). Also 83 copies of questionnaire were used in the analysis. Results showed positive correlation between rainfall and relative humidity (0.517 and 0.747) and an R2 of 39.98% with implies that, the higher the rainfall the higher the relative humidity, and by extension the higher the frequency of deadly poultry diseases (Coccidiosis, Gumboro, Fowl cholera, Fowl typhoid) and mortality especially for broilers as the cell immune response of layer birds in defending itself against diseases and viruses are greater than that of broilers. While Newcastle diseases, Fowl pox, Fowl typhoid, chronic respiratory diseases mostly affect birds in the dry season (NovemberMarch). While Newcastle diseases, Fowl pox, Fowl typhoid, chronic respiratory diseases mostly affect birds in the dry season (NovemberMarch).In conclusion, seasons of the year affect poultry and its production in particular in Owerri urban. It is recommended that farmers should make sure they adopt proper roofing methods, as well as maintain good sanitation/hygiene practices to minimize heat and the occurrence and spread of diseases which may adversely affect birds across seasons. Keywords— Season, poultry birds, diseases, mortality.


INTRODUCTION
Poultry are birds such as the domestic fowl, Turkey, Duck, Gesse, Ostrich etc which render not only economic services but contributes significantly to human food as a primary supplier of meat, egg and raw materials to industries (feathers, waste production). It also serves as source of income and employment to people compared to other domestic animals, their production is one that plays significant contribution to food for human consumption (Demeke, 2004). Poultry flocks are particularly vulnerable to climatic variations because there is a range of thermal conditions within which animals are able to maintain a relatively stable temperature (Adesiji, Baba and Tyabo, 2013).
In many African countries, poultry generally and its production in particular make substantial contribution to relive the protein insufficiency, about 80% of poultry production in Africa is found in rural and peril-urban areas where birds are raised in small numbers by the traditional extensive or semiintensive, low input, low output systems (Faostat, 2012). Poultry production in Nigeria is an important component of the livestock sub-sector ISSN: 2456-1878 https://dx.doi.org/10.22161/ijeab.63. 2 17 and has developed to the level of enterprise. Involving thousands of birds that provide employment, income, animal protein for rural and urban dwellers as well as manure for production of crop (Arhyel,et al., 2014). Poultry plays an important role for alleviating challenges associated with poverty in Nigeria (food security and malnutrition) and significantly contributes to women's income and help meet some level of household protein needs (Arhyel et al., 2014). It plays an important role in the diet and economy of Nigeria. Poultry birds are efficient converters of feed to egg and meat within a short period of time and in terms of nutritive value, poultry egg ranks second to cow milk (Adesiji et al., 2013). Agriculturists and nutritionists have generally agreed that developing the poultry industry of Nigeria is the fastest means of bridging the protein deficiency gap presently prevailing (Amos, 2006).
In Nigeria, there are two seasons, dry and rainy seasons. The rainy season begins by April and lasts till October whereas the dry season begins November and lasts till March (Odekunle, 2004). These seasons have their various effects not only on living things, poultry inclusive but also on non living things (Osaguona , et al., 2007). Season comes with various pathogenic disease occurrence , morbidity and mortality rate is majorly a factor of the type of management practices and vaccination of flocks (Kelly-Hope and Thomson , 2008). ). Poultry flocks are particularly vulnerable to seasonal changes because there is a range of thermal conditions within which animals are able to maintain a relatively stable body temperature in their behavioural and physiological activities (Ayo-Enwerem , Ahaotu, Nwogu and Opara, 2017).
Seasonal variation is one of the major threat to poultry production and also an important factor associated with incidences of diseases and mortality (Singh, et al., 2005;Nayak, et al., 2015). Disease and climate problems are seen as major limitations to modern animal husbandry in the tropical areas, coupled with high relative humidity in mostly chicken's pen, leads to mortality of young poultry birds (Smith, 2001). Variation due to season affects the severity and distribution of livestock diseases and parasites which adversely influence poultry production (Thornton, 2010). Diseases remains a major threat affecting the boost of the industry in Nigeria (Adewole, 2012). Major diseases are Newcastle diseases, Avian influenza, Avian pox, infectious burals diseases, coccidiosis, colisepticemia and worm infestation (Usman and Diarra, 2008). Due to diseases, productivity is reduced resulting to less meat, fewer eggs and high mortality. Therefore this study was carried out to investigate if seasons of the year have influence on disease frequency and mortality of chickens in the study area.

Study location
Owerri, the Imo State capital lies at the intersection of six major roads of regional importance namely: Aba road, Okigwe road, Mbaise/Umuahia road and Orlu road. It is located within latitude 5 º 25 '10 N and 5 º 30'15N and longitude 7 º 10E and 7 º 40'E and occupies a land area of about 104 square kilometers. It lies within the humid tropical climate with annual rainfall and temperature of over 2000 mm and 20ºC respectively. And occupies a land area of about 104 square kilometers.

Method of data collection
The study deployed the quasi experimental research design. Data for rainfall, temperature, relative humidity and mortality was collected from Nigerian Meteorological Agency (NIMET) Sam Mbakwe International Cargo Airport Imo State and Ministry of Livestock Development Owerri for a period of 16 years respectively. Also 83 copies of questionnaire retrieved from farmers was used. Data was analyzed using Pearson's moment correlation, stepwise regression and linear regression to ascertain variations in disease/mortality across seasons from(2004-2019). The analysis was done using statistical package for social sciences (Spss version 21).

III. RESULTS AND DISCUSION
The table 1 shows monthly climatic data of maximum temperature, minimum temperature, mean temperature, relative humidity, total rainfall and number of birds mortality. which shows that bird's mortality is higher in the rainy season.

3.1: Effects of season on disease frequency and mortality of chickens
The positive correlation value of (0.517 and 0.747), shows that the higher the relative humidity and rainfall for the years under investigation, the higher the probability of frequency of diseases and mortality of poultry birds. Relative humidity and rainfall which are indicators of rainy season are less than the alpha level of 0.05 and indicate that the two variables are statistically significant with disease frequency and mortality of poultry birds.
Stepwise regression model was carried out to ascertain which predictor variables has more effect on diseases frequency and mortality of poultry birds. The regression model obtained has an R square value of 0.3998 which means about 39.98% variations in disease frequency and mortality of bird's is determined by relative humidity and rainfall.

3.2: Trends of seasonal variations in disease frequency and mortality
The trend analysis shows seasonal variation in disease frequency and mortality of birds, for the months of January and July for the span under investigation. The months of January represents the dry season while the months of July represents the rainy season for a period of sixteen years (2004 -2019).The mortality plot also was used to access outbreak of poultry disease. in disease frequency and mortality rate affecting poultry birds across the seasons. Table 4 shows statistics report of the answers provided by the respondents who attended to the structured questionnaire for this research purpose.

IV. CONCLUSION
The correlation analysis on effects of seasons of the year on disease frequency and mortality of chickens was carried out and it revealed a positive (r=0.517 and r= 0.747) with relative humidity and rainfall which are indicators of season. It implies that the higher the relative humidity and rainfall for the years under consideration, the higher the frequency of diseases and mortality of poultry birds, therefore seasons of the year have influence on disease frequency and mortality of chickens in the study area. The co-efficient of determination (CD) obtained, which is in percentage implies that 39.98% of disease frequency and mortality is explainable by relative humidity and rainfall which are indicators of the rainy season. This report is in agreement with (Uddia et al., 2010) who noted that rainy season are most vulnerable to various poultry diseases. (Sato et al., 2002), also noted that, due to cold stress birds increase their susceptibility to a number of infectious and non -infectious agents. Also (Nayak et al., 2015), noted that higher rainfall and relative humidity increases diseases incidence on poultry birds.

V. RECOMMENDATION
It is recommended that farmers should make sure they select species that are suitable and can resist the prevailing conditions due to variability in season in the study area as well as to the prevailing diseases. There is also the need for appropriate stocking of birds for free movement and space, adoption of proper roofing methods, vaccinating the birds when due, maintaining good sanitation/hygiene practices to minimize heat and the occurrence and spread of diseases which may adversely affect birds across seasons.

VI. COMPETING INTERESTS
Authors have declared that no competing interest exits.