Indigenous African Breeds Research Articles

Breeding pure and crossbreeds of European cattle breeds for milk production improvement under tropical climate conditions-a review.

The aim of this review was to present the breeding status of pure or crossbreeds of European cattle with African indigenous cattle in order to improve milk yield in African tropical conditions. As the African indigenous breeds are characterized by small size, low body weight (300-450 kg) and low production performances (less than 1000 kg per lactation), short lactation length (205-240 days), etc., the crossbreeding with pure European cattle was done in order to ameliorate production performances especially milk and beef production. As results, it was seen that F1 offspring improved output productions than their parents of tropical origin. Also, it was seen that F1 offspring showed disease and heat resistance than their parents of temperate climate origin. However, at different degrees of crossbreeding, it was seen that the offspring can demonstrate bad production performances than their parents and therefore, the crossbreeding has to respect a certain degree. Other consequences are that the crossbreeding of local and pure European cattle breeds has resulted in calving complications in African local cattle. In African indigenous cattle, the selection as an improvement tool was given less emphasis as a solution to improve output production. That is why, the implementation of a well-prepared selection programs could be practiced in African indigenous cattle in order to preserve African cattle genotypes, as they are endangered of extinction due to various crossbreeding with exotic cattle breeds.

Whole-genome resequencing reveals molecular imprints of anthropogenic and natural selection in wild and domesticated sheep

The abundance of domesticated sheep varieties and phenotypes is largely the result of long-term natural and artificial selection. However, there is limited information regarding the genetic mechanisms underlying phenotypic variation induced by the domestication and improvement of sheep. In this study, to explore genomic diversity and selective regions at the genome level, we sequenced the genomes of 100 sheep across 10 breeds and combined these results with publicly available genomic data from 225 individuals, including improved breeds, Chinese indigenous breeds, African indigenous breeds, and their Asian mouflon ancestor. Based on population structure, the domesticated sheep formed a monophyletic group, while the Chinese indigenous sheep showed a clear geographical distribution trend. Comparative genomic analysis of domestication identified several selective signatures, including IFI44 and IFI44L genes and PANK2 and RNF24 genes, associated with immune response and visual function. Population genomic analysis of improvement demonstrated that candidate genes of selected regions were mainly associated with pigmentation, energy metabolism, and growth development. Furthermore, the IFI44 and IFI44L genes showed a common selection signature in the genomes of 30 domesticated sheep breeds. The IFI44 c. 54413058 C>G mutation was selected for genotyping and population genetic validation. Results showed that the IFI44 polymorphism was significantly associated with partial immune traits. Our findings identified the population genetic basis of domesticated sheep at the whole-genome level, providing theoretical insights into the molecular mechanism underlying breed characteristics and phenotypic changes during sheep domestication and improvement.

African Indigenous Cattle: Unique Genetic Resources in a Rapidly Changing World.

At least 150 indigenous African cattle breeds have been named, but the majority of African cattle populations remain largely uncharacterized. As cattle breeds and populations in Africa adapted to various local environmental conditions, they acquired unique features. We know now that the history of African cattle was particularly complex and while several of its episodes remain debated, there is no doubt that African cattle population evolved dramatically over time. Today, we find a mosaic of genetically diverse population from the purest Bos taurus to the nearly pure Bos indicus. African cattle are now found all across the continent, with the exception of the Sahara and the river Congo basin. They are found on the rift valley highlands as well as below sea level in the Afar depression. These unique livestock genetic resources are in danger to disappear rapidly following uncontrolled crossbreeding and breed replacements with exotic breeds. Breeding improvement programs of African indigenous livestock remain too few while paradoxically the demand of livestock products is continually increasing. Many African indigenous breeds are endangered now, and their unique adaptive traits may be lost forever. This paper reviews the unique known characteristics of indigenous African cattle populations while describing the opportunities, the necessity and urgency to understand and utilize these resources to respond to the needs of the people of the continent and to the benefit of African farmers.

Dog genome evolution: A strategy to segregate biogeographic effects from human selection

The article of Boyko et al. (1) supports the general biological rules underlying evolution: barriers to gene flow will result in genetic drift. In contrast to wild animals, in dog populations this is modified by human selection. The weighted center of the principle component analysis explaining 38% of the variance (figure 4 in ref. 1) indicates that dogs of northern Namibia and Egypt (>5,000 km apart) show little genetic difference consistent with a continuous gene flow across the African continent. In contrast, the Middle Eastern Salukis and the Afghan hounds (from Afghanistan) differ more substantially from Western indigenous African dogs of Egypt (only 2,500 km apart, or half the distance between Namibia and Egypt). This difference underscores that biogeographic distance is distorted by other factors such as barriers to gene flow and human selection. The case of the Basenji highlights this discrepancy even better: Basenjis come from the Congo basin and one would expect them to be genetically somewhere between Ugandan and northern Namibian village dogs—the Congo basin being situated slightly off but somewhat between Uganda and Namibia. The great genetic differences of the Basenji from these village dogs suggest that other factors such as breeding preferences in the countries of origin or a small Western breeding stock from which the samples were taken has perhaps distorted biogeographic differences. Controlling for this aspect would require a direct comparison between local village dogs and breeds originating from the same areas. Existing data suggest that both segregation [Sloughis and North African village dogs (2)] as well as some intermixing [Salukis with Akbash (3)] will be found between Western dog breeds and other local dogs in the country of origin. More such comparisons of internationally recognized* indigenous African breeds such as Aidi, Azawakh, Basenji, and Sloughi with biogeographically overlapping village dogs would complement this study and would reveal the influence of biogeographic differences and human selection better than comparing with breeds originating outside of Africa (e.g., Afghan Hound, Pharaoh Hound, Saluki).

Comparative performance of Landim and Blackhead Persian sheep in Mozambique

Larger litter sizes of Landim sheep (1.38 lambs per parturition) compared to Blackhead Persian (BHP) (1.00) and BHP X Landim (1.00), and similar parturition intervals in each genotype (342 days) resulted in greater annual output of young in the Landim (1.71) than in BHP (1.17) or in BHP x Landim (1.25). Weights of all three genotypes were similar at birth (2.5 kg), at 90 days (12.5 kg), at 150 days (15.0 kg) and at 365 days (28.1 kg). Breed did not affect the death rate at any of 10 days (4.9%), 30 days (6.7%), 90 days (11.9%) or 150 days (19.6%) of age. Output of weaned lambs per breeding ewe per year was slightly (P< 0.1) higher in crossbred (23.3 kg) than in Landim (19.7 ) or BHP (19.4 kg) but output per kg live weight of ewe (488 g) and per kg 0.73 live weight of ewe (1.36 kg) did not differ among the genotypes. Year, season, type of birth, sex and ewe age significantly influenced most traits. Overall performance of Landim sheep was not different to that of the BHP indicating little if any advantage in using BHP. Landim sheep have large litter sizes in comparison to other African indigenous breeds and could themselves be used to improve reproductive performance of other strains of sheep.