Geographical Distribution of Zebu Breeds in Brazil And Their Relationship With Environmental Variables and Human Development Indicator

The aim of this study was to evaluate the geographical distribution of zebu breeds in Brazil and correlate their occurrence with environmental variables and human development indicator. The herds of purebred zebu cattle in Brazil were classied as beef breeds (Brahman, Polled Brahman, Nelore, Polled Nelore and Tabapuã), dairy breeds (Gir and Polled Gir), and dual-purpose breeds (Guzerá, Indubrasil, Polled Indubrasil, Sindhi and Polled Sindhi), all breeds being spatialized in ArcGIS program. Variables examined included environmental and human development indicator. The statistical analysis included analysis and logistic regression.The lower distribution of zebu cattle in the states of Northeast compared to other locations is probably due to its extreme climate, highly susceptible to long periods of high temperatures and lower precipitation, which directly affects local livestock. The beef breeds were evenly spread throughout the country. The location occupied for beef breeds was inuenced by environmental variables, showing a higher incidence with increased precipitation, normalized difference vegetation index (NDVI), temperature, relative humidity and temperature humidity index (THI), as well as establishments without family agriculture and rivers and streams with forest protection. The location used for dual-purpose and dairy breeds was inuenced by areas with cultivated cutting forages, areas with integrated crop-livestock forest systems and areas with rotational grazing system, indicating a higher occupation in fertile lands. The Gir breed, the only one with dairy exploration in this study, showed herds in establishments with family agriculture, characterized by small to medium farms, and in regions with higher altitude. intensication as the means for the cattle to reduce pressure on margins and free-up land for soybean or sugarcane production. showed that this expansion resulted in a signicant reduction of and number of cattle and higher economic growth compared to neighboring areas. Maranhão showed soybean production replacing cattle production in the savanna region of Brazil. The latter migrated to the Amazon region which may explain some of the results seen here, with cattle seen in regions with higher temperatures and lower rainfall. Nevertheless, there are large regions of with these productions as other for alternative sources of feeding, especially for dairy and dual-purpose cattle.


Introduction
Brazil is important in the world scenario due to its high agricultural potential, related to an increased demand for world food consumption, leading farmers to seek more e cient production systems to offer a high quality product at low cost (Faria et al. 2008). Cattle breeders have been looking for improved and more e cient animals, leading to the introduction of different bovine breeds in the country, among them zebu breeds that, due to their exible adaptability, currently represent around 80% of the national herd (Abiec 2015). However, little attention has been given to the distribution of these different genotypes in Brazil correlated to the environment. According to Carneiro et al. (2006), differences among herds in production variability have generally been attributed to differences in local or regional climatic factors and in the management types of each herd.
The continental proportions of the country, i.e large territorial extension, contribute to the heterogeneity of the cattle systems (McManus et al. 2016), determined in great part by the differences among climate, economy and natural resources availability related to animal production. This diversity of environments provides opportunities for the same genotype to express itself differently, making it di cult to identify genetically superior individuals (Lopes et al. 2008) regardless of breed. Thus, the genotype environmental interaction, attributed to geographic distribution in Brazil, must be analyzed in different environments to determine its effect on the animal (Baye et al. 2011), since it can cause changes in genetic, phenotypic and environmental variances, thus modifying the estimated genetic and phenotypic parameters (Diaz et al. 2011).
According to Thornton et al. (2007), changes in climatic conditions may generate unknown changes in the adaptation of animals, especially in developing countries, where stressors are more intense and the volume of changes expected is greater. Moreover, information on the impacts of climate stress on the wide Therefore, the aim of this study was to evaluate the spatial distribution of zebu breeds registered in Brazil and to seek a possible link with environmental variables and human development indicator.

Material And Methods
The location of all herds of purebred zebu cattle in Brazil was obtained from the genealogical register of the Brazilian Association of Zebus Breeders (ABCZ) and spatialized by municipality. The breeds were classi ed as beef breeds (Brahman, Polled Brahman Nelore, Polled Nelore and Tabapuã), dairy breeds (Gir and Polled Gir), and dual-purpose breeds (Guzerá, Indubrasil, Polled Indubrasil, Sindhi and Polled Sindhi) ( Table 1).
Where Y is the number of animals or herds in a municipality, ENV are the environmental factors in the study and BREED are the breeds.
The differences were tested by the Tukey test (P < 0.05). Logistic regression (PROC LOGISTIC) was performed to test the presence of breed types (beef, dairy and dual-purpose) according to environmental variables and human development indicator, where the breed types was considered the dependent variable and environmental variables and human development indicator as independent variables.
The logistic regression was:log Env are the environmental variables tested.
Model selection was carried out considering Nagelkerke's R 2 , area under the ROC curve, Akaike information criterion (AIC) and Schwarz's Bayesian information criterion (BIC).

Results
The highest concentration of animals per area was observed in the Centerwest region, followed by the Southeast and part of the North, mainly due to state of Pará, Northeast and nally the South region, which showed a lower frequency of zebu cattle breeds. The Nelore breed was widely distributed throughout the country, corroborated by the midpoint of the breed that was in the geographic center of the country (Fig. 1). The midpoint of the Sindhi breed was more towards Northeast, central area of Bahia (BA) and for the Brahman breed more to the South, near the junction of Mato Grosso do Sul (MS), São Paulo (SP) and Minas Gerais (MG) States. However, there was a trend towards centralization of the midpoints of the breeds across the country.
The correlation between the geographical midpoints calculated with reference to the number of herds and the number of animals was above 0.90 for both latitude and longitude, showing that both can be used to exemplify the results (Fig. 1). The distribuition of herds is shown in Fig. 2. Most breeds show a nationwide distribution, except for Sindhi and Indubrasil as well as polled breeds.
When analyzing the national distribution of zebu breeds by type of production, for beef and dual-purpose breeds (Fig. 3), it was observed that 80% of the herds were less than 1,000 km from the midpoint of the breeds and for dairy breeds, 80% of the herds were up to 800 km from the midpoint, except for the Polled Sindhi (dual-purpose) and Polled Indubrasil (dual-purpose), which presented 80% of the herds less than 500 km from the midpoint (Fig. 4).
The analysis of variance (ANOVA) showed that Nelore, Polled Nelore, Brahman and Tabapuã breeds occurred in areas with higher precipitation ( Table 2). Beef breeds usually occurred in areas with higher precipitation, NDVI and relative humidity. The logistic regression also showed that higher precipitation, NDVI, relative humidity, temperature and THI favored the beef breeds (Fig. 5). In contrast, with dairy breeds, the probability of occurance of dairy breeds reduced with an increase in these measures. Dual-purpose breeds were little affected.  Polled Brahman, Nelore and Sindhi breeds occurred in areas with cultivated pasture in good condition (CPGC), although Polled Brahman occurred in areas, with higher HDI while Sindhi in areas with lower HDI in uencing the geographic distribution of these breeds. Beef and dairy breeds occurred in areas with higher HDI, and in CPGC there was a higher occurrence of beef breeds (Table 2).
Dairy breeds occurred in areas with higher altitude, followed by beef and dual-purpose breeds (Table 2), as seen in the logistic regression analysis where the variation to 1,500 meters led to a ± 50% increase in probability of occurrence of the dairy breeds, and the increase in altitude caused a decrease in the probability of occurrence of meet breeds. For dual-purpose breeds, there was no effect on the occurrence with the altitude increase (Fig. 5).
The presence of rivers and streams with forest protection (RSFP) and rivers and streams without forest protection (NRSFP) shown signi cant for the occurrence of breeds by type (Fig. 5). In areas with cultivated cutting forages (CCF), a higher occurrence of dual-purpose and milk breeds was seen. The increase of 50 ha in CCF re ected an increase of ± 50% in the occurrence of dairy and dual-purpose breeds (Fig. 5). A higher occurrence of beef breeds was seen both in areas with degraded cultivated pastures (DCP) and areas with cultivated pasture in good condition (CPGC) ( Table 2).
In areas with integrated crop-livestock forest systems (ICLFS) there was a higher occurrence of dual-purpose breeds, followed by dairy and beef breeds ( Table 2). As observed in the logistic regression, the increase from 20 to 80 ha in ICLFS caused an increase from ± 12.5 to ± 95% in the probability of occurrence of dual-purpose breeds. For dairy breeds, the increase in the probability of occurrence was 50%, and for beef breeds decreased the probability of occurrence (Fig. 6).
A trend towards dairy breeds was observed in establishments with family agriculture (EFA) (Fig. 6). Establishments without family agriculture (NEFA), presented a higher occurrence of beef type, corroborating with the regression analysis where very latifundio farms explored beef breeds (Table 2 and Fig. 6).
The use of management technologies, such as rotational grazing system (RGS) favored the occurrence of dual-purpose breeds when compared to the others (Table 2). This difference was more visible in the logistic regression, where the increase from 5 to 20 ha in the RGS caused an increased from ± 5 to ± 75% in in the probability of occurrence of dual-purpose breeds. However, this management decreased the probability of occurrence of beef breeds (Fig. 6).

Discussion
The zebu breeds analyzed were all pure in origin (PO), that is, genealogical registered by the Brazilian Association of Zebus Breeders (ABCZ occurred in the Midwest, followed by the Southeast and North, explained by their well known livestock farming aptitude. This was evident with the position of the midpoint of these breeds, being almost all located in the central region of the country, as seen by Teixeira and Hespanhol (2014) and McManus et al. (2016), who observed the same location as the midpoint for all cattle production in Brazil. These last authors, looking at the dynamics of cattle production in Brazil show a tendency towards north western regions which has implications not only for environmental factors, such as pasture type, temperature and humidity but also for the need of political and infrastructure changes, aiming to fostering the livestock sector.
The lower occurrence of zebu cattle breeds in the South region was due to the traditional use of European breeds, as veri ed by Braga et al. (2015). Regardless of the type of use, the proportion of herds with European breeds increases the further one moves towards the southern states of the country.
In the states of the Northeast, a region known as the drought polygon, a smaller occurrence of zebu cattle herds was observed due to their highly susceptiblity Geographic distribution maps showed an expected trend, where the Nellore breed is widely distributed throughout the country (Fig. 2), possibly due to its adaptation to different environments (Bianchini et al. 2006). The Indubrasil breed, developed by crossbreeding in Brazil, was highly used in the middle of the last century (Santiago 1975), but interest has decreased in its use (Carneiro et al. 2009). Calculating the midpoint also helps us understand breed distribution and eventual need for conservation measures (McManus et al. 2014b). For example, breeds with low distribution from the midpoint are more vulnerable to climatic or health disasters.
The national distribution of the zebu cattle breeds when analyzed by type of production, beef, dairy and dual-purpose showed that the majority of herds (80%) are less than 1,000 km from the midpoint of the breeds. This proximity between the herds can lead to problems, such as breed loss during possible health epidemics and increased inbreeding due to a possible lack of effective numbers of animals. Therefore increased crossbreeding may arise reducing purebred numbers. Complementary results were veri ed when the breeds were analyzed by type (beef, dairy and dual-purpose). Beef breeds usually occurred in areas with greater precipitation, NDVI, temperature, THI and relative humidity, that is, in more humid and also showed that implementation of hygiene regulations on farms was limited by lack of understanding of the importance of these measures by cattle farmer, as well as lack of adequate infrastructure such as electri cation and roads. Distribution studies such as the present one can thereby help to identify where increased public policies ( scal incentive, access to nance, among others), infrastructure, and specify training are necessary to improve the production.
However, beef type also occurred in areas of rivers and streams with forest protection (RSFP), and establishments without family farming (NEFA), probably due to the high number of animals of this type in data worked, favored by the aptitude of the market, as seen also by McManus et al. (2014b) in a study with sheep breeds distribuiction in Brazil. Also, these beef breeds had a high distribution in the Brazilian territory in uenced by the commercialization made by the Breeders' Associations of Brazil, which may also have favored beef Zebu breeds.
In areas with cultivated cutting forages (CCF), areas with rotational grazing system (RGS), and areas with integrated crop-livestock forest systems (ICLFS), there was a higher occurrence of dual-purpose and dairy breeds, characteristics of more fertile soils. This was also seen by McManus et al. (2014a) and McManus et al. (2016) who observed an increase in breeds with dairy aptitude in more productive regions. In addition, dairy production can be more favored in areas with greater elevation in relation to sea level, maybe due to better climatic conditions. Forest protection for rivers and streams was important for climate regulation, heat absorption and humidity regulation (Silvano et al. 2005). Nevertheless, in recent years, there has been a reduction in this protection (Taniwaki et al. 2017), especially due to corn plantations for silage, sugarcane plantations, citrus, silviculture, urbanization, and pasture creation which have been shown to be linked to dairy cattle production (Costa et al. 2014). Most farms do not have shade protection or adequate water supply for cattle (Costa et al. 2013), which directly affects performance.
A trend towards dairy breed occurrence was observed in establishments with family agriculture (EFA [1]), showing a historical tendency, where small to medium-sized properties managed by families usually explore dairy breeds. This was also seen by Guilhoto et al. (2006) and Wilkinson (2013), as well as agricultural research data (IBGE 2012), where more than 80% of the farms fall into this category.
The present study looked at breed occurance relative to environmental and socio-economic factors. As one factor changes, so may others and the cattle seen in regions with higher temperatures and lower rainfall. Nevertheless, there are large regions of overlap with these productions as well as other crops due to the need for alternative sources of feeding, especially for dairy and dual-purpose cattle.
[1] "Family Agriculture" is considered as de ned in the Item II of Article 4 of the Land Act, Law No. 4504 of November 30, 2004: "a farm that is directly and personally operated by the farmer and his family, to absorb their entire workforce, providing them with subsistence as well as social and economic progress, with a maximum area xed by region and type of operation, and occasionally worked with the help of others."

Conclusion
Zebu cattle breeds showed high adaptability to a broad range of climates, but environmental variables and human development index in uenced the distribution of these breeds of cattle in Brazil. Preventive measures need to be taken for the conservation of Polled Sindhi and Polled Indubrasil due to thir low geographical distribution making them vulnernable to change. The correct interpretation of these results can contribute to better understand the adaptation of each zebu breed individually to different environments, helping in the correct choice of the breed to be explored.