The genetic architecture of climatic adaptation of tropical cattle.

Laercio R Porto-Neto,Tad S Sonstegard,John M Henshall,Sigrid A Lehnert,Michael E Goddard,Geoffry Fordyce,Jose Fernando Garcia,David J Johnston,Kishore C Prayaga,Antonio Reverter,Eva K F Chan,Rachel J Hawken,William Barendse,Heather M Burrow,Sunduimijid Bolormaa

doi:10.1371/journal.pone.0113284

Abstract

Adaptation of global food systems to climate change is essential to feed the world. Tropical cattle production, a mainstay of profitability for farmers in the developing world, is dominated by heat, lack of water, poor quality feedstuffs, parasites, and tropical diseases. In these systems European cattle suffer significant stock loss, and the cross breeding of taurine x indicine cattle is unpredictable due to the dilution of adaptation to heat and tropical diseases. We explored the genetic architecture of ten traits of tropical cattle production using genome wide association studies of 4,662 animals varying from 0% to 100% indicine. We show that nine of the ten have genetic architectures that include genes of major effect, and in one case, a single location that accounted for more than 71% of the genetic variation. One genetic region in particular had effects on parasite resistance, yearling weight, body condition score, coat colour and penile sheath score. This region, extending 20 Mb on BTA5, appeared to be under genetic selection possibly through maintenance of haplotypes by breeders. We found that the amount of genetic variation and the genetic correlations between traits did not depend upon the degree of indicine content in the animals. Climate change is expected to expand some conditions of the tropics to more temperate environments, which may impact negatively on global livestock health and production. Our results point to several important genes that have large effects on adaptation that could be introduced into more temperate cattle without detrimental effects on productivity.

Highlights

Cattle are a key component of tropical rural sustainability, wealth, and food production for small holder farms, which are vital for global food security [1,2]
We have used a large sample of crossbred cattle of two types in genome wide association studies (GWAS) to analyse 10 traits that are important in extensive tropical environments
To determine whether there are genes of large effect segregating in taurine x indicine composite cattle we performed a genetic analysis of ten traits that are relevant for improved performance in tropical production systems (Table 1, Table S1)

Summary

Introduction

Cattle are a key component of tropical rural sustainability, wealth, and food production for small holder farms, which are vital for global food security [1,2]. We have used a large sample of crossbred cattle of two types in genome wide association studies (GWAS) to analyse 10 traits that are important in extensive tropical environments. Such traits include overall productivity and yearling weight, heat and parasite tolerance, and temperament. We show that contrary to the general expectation of a large number of genes each of infinitesimally small effect, that 9 of the 10 traits were affected by genes of moderate to large effect size This suggests that for tropical productivity, the genetic differences between indicine and European taurine cattle includes the segregation of genes of large effect

Results and Discussion

41 IGFBP4

Materials and Methods