Abbreviations: AI, artificial insemination; ANFs, antinutritional factors; BHP, black head persian (sheep); BSE, bovine spongiform encephalopathy; EAZ, east african zebu; ET, embryo transfer; FAO, food and agriculture organization; LN, liquid nitrogen; MAS, marker assisted selection; MARI, mikocheni agricultural research institute; MOET, multiple ovulation and embryo transfer; MPTs, multipurpose trees; NAIC, national artificial insemination centre; NARCO, national ranching company; PCR, polymerized chain reaction; PRNP, prion protein gene; SEA, small east african (goats); SFC, sunflower cake; SNP, single nucleotide polymorphism; SUA, sokoine university of agriculture; TBDs, tick-borne diseases; TVLA, tanzania veterinary laboratory agency; TZS, tanzania shorthorn zebu (cattle); UNCED, united nations conference on environment and development IntroductionRecently annual per capita intake of animal protein in Tanzania was estimated to be 15kg of meat, 47litres of milk and 106 eggs. These figures are lower compared to the rates recommended by United Nation's Food and Agriculture Organization (FAO) of 50kg of meat, 200litres of milk and 300 eggs per person per year.1 As a result, Tanzania was listed among top 10 countries in the world and third in Africa in number of undernourished children.2 Problem of food insecurity including animal protein deficiency in particular among children under five years of age and pregnant women is expected to widen further ahead 2050.2 At the same time, the country is ranked third in Africa in numbers of livestock with estimated 25.8milion heads of cattle, 16.7million goats, 8.7million sheep, 2.4million pigs and about 70million chickens. Furthermore, production of animal products such as meat, milk and eggs has increased significantly in recent years. For example, meat production has increased by over 6.2percent to 597,757 tonnes in 2015.1 Milk production increased by 130% over the last decade to about 2.25billion litres in 2015 3 and over 4billion eggs were estimated in 2015.1 However, it is generally agreed that the increases have not met the greater demand for these products evidenced by the low consumption rates and hiking prices in local markets in the country. Also, the increases are due to increase in number of animals but not productivity per animal.3 A larger percent of animals raised in Tanzania belong to the native populations which have been characterized to be low producers of meat, milk and eggs due to poor genetic potential.4-6 For example, Tanzania Shorthorn Zebu (TSZ) animals which form 95% of all cattle and produce over 70% and 90% of milk and meat respectively are characterized by slow growth rates, low mature weight, long calving intervals, as well as low meat and milk yield.1 Of the 16.7million goats about 98% belongs to the native Small East African (SEA) breed estimated to have low growth rates between 5 and 7g/day, small mature size ranging from 20 to 25kg and low carcass weights about 6 to 13kg. 6,7 Likewise productivity levels and reproductive efficiency are als...