IMPACT OF CLIMATE CHANGE AND VARIABILITY ON PHYSIOLOGICAL RESPONSE, BLOOD PROFILE, GROWTH PARAMETERS, AND POPULATION DYNAMICS OF FOGERA CATTLE IN AWI ZONE, NORTHWESTERN ETHIOPIA

Abstract

This study was conducted with the objectives of assessing the perception of Fogera cattle farmers on climate change and variability, the impact of climatic variability on the growth performance of Fogera cattle, the effect of heat stress (HS) on physiological, hematological, biochemical, and growth parameters of Fogera cattle calves during different seasons and analyzed the impact of climate change and land use/cover (LULC) on Fogera cattle population dynamics. The Awi zone was clustered into three agroecology based on the altitudinal variation, and primary data was collected from 150 households having at least 3 Fogera cattle through systematic random sampling while secondary data were sourced from unpublished documents of zonal and district agricultural offices. Over 36 years (from 1983 to 2019) of meteorological data were taken from the National Meteorological Agency (NMA). For trend analysis all animals born and calves that were weaned from 2005 to 2019 were used in this study. Furthermore, a total of 72 calves (24 for each season) of 6 months of age with an equal number of males and females were used for physiological, hematological, biochemical, and growth parameters study. Daily ambient temperature (AT) and relative humidity (RH) recorded two times per day throughout the study periods were used to calculate the daily temperature-humidity index (THI) that can serve to assess the HS condition of the ranch location. Landsat images of 1986, 2000, and 2019 were used to generate LULC of the study area. For LULC classification supervised image classification using the maximum likelihood classifier in ERDAS imagine software was used. A total of 303 samples were collected using a global positioning system (GPS) and used for accuracy assessment. Moreover, data for Fogera cattle numbers from 1986 to 2019 were taken from the record book of the ranch. Likewise, pasture land data that was used for grazing purpose was obtained from the classified images of these years. Based on the nature of the data, data were analyzed by least squares means analysis of variance using R software version 3.5.2 program and PROC GLM using SAS software version 9.4. Moreover, a multiple linear regression model was also used to regress the contribution of climatic variables on growth parameters. Furthermore, to check the variability of annual rainfall standardized anomaly index was calculated. The survey result revealed that 97.13% of the farmers were experiencing climate change in all agro-ecologies. The annual temperature trend was increasing while rainfall was declining from time to time. About 80.91% of Fogera cattle farmers reported experiencing negative impacts of climate change and variability on cattle during severe water shortages. The frequency of drought, duration of the dry spell, wind, and floods were increasing (p<0.001) in all the agro-ecologies. Moreover, about 84.48, 65.3, and 60.47% of Fogera cattle farmers in the lowland, midland, and highland, respectively perceived xviii that increasing cattle mortality in the areas (p<0.001). The meteorological data result also confirms that climate was changing across the agro-ecologies. Both the mean annual maximum and minimum temperature were considerably increasing for all agro-ecologies whereas the mean annual rainfall was decreasing which, was consistent with the farmers' perception. The meteorological result also showed that the rainfall during short rainy season and dry season shows high interannual variability. The trends in birth weight (BW) and weaning weight (WW) of calves were significantly decreasing along the study period. The result also indicated that the RH and AT regression coefficient was negative for BW and WW. The Pearson correlation coefficient also indicated that there was a negative relationship between growth parameters and climatic variables. When THI increases from 67 to 72, the BW and WW of the calves were decreased by 3.5 and 25 kg, respectively. However, higher BW and WW were recorded for the optimum THI less than or equal to 67. Physiological parameters, except rectal temperature, were affected by the seasons. Hematological parameters were also affected by season except for packed cell volume. Biochemical and growth parameters were also significantly affected by the seasons. The result also revealed that between 1986 and 2019 expansion of farmland and forest was exhibited in the ranch, which has increased by about 34.8 and 0.4 ha, respectively. However, the area covered by grazing land and shrub has shown a decreasing trend over the entire study period with a rate of - 13.7 and -21.5 ha, respectively. The overall trend analysis result showed that the Fogera cattle population was significantly increasing whereas, the pasture land was decreasing during the study period. The increase in Fogera cattle population from 1986 to 2000 was due to an increase in pasture land. However, the cattle numbers declined from 2000 to 2019 due to a reduction in pasture land in these years. Moreover, the overall stocking rate for grazing land was also increasing from 1986 to 2019, with an annual change rate of 0.8%. The lower BW and WW of calves observed in this study might be due to the cumulative effect of the climate conditions of the study area and herd management practices. Climate change and variability in the past 30 years attested by farmers and meteorological data harms herd size, feed availability, water availability, and growth performance of Fogera cattle in the study areas. However, the positive performance in terms of growth parameters in the thermo-conformable zone in the different seasons suggests the need to consider ameliorative strategies such as appropriate feeding, housing, and health care in the breed improvement and conservation program in the future. Generally, the THI value of 66 can be considered optimum for high weight gain and normal physiological responses to HS in Fogera cattle calves under their current production system