No abstract

The Tanzanian goat (Capra hircus) population is currently estimated to be 24.1 million (NBS, 2020) with 97% comprising of indigenous goats belonging to the Small East African (SEA) goat breed (MLF, 2017). Due to their adaptability to different climatic conditions, the indigenous goats are widely distributed in almost all agro-ecological zones of Tanzania. Goats are important species for the livelihood of the rural farming communities especially those residing in arid and semi-arid areas of Tanzania where other agricultural activities are

This research aimed at describing reasons for keeping dairy goats in Tanzania, and possible goals for a sustainable breeding program. Three districts, each representing a unique dairy goat breed population, were selected for the study. The Saanen, Toggenburg and Norwegian were the main dairy goat breeds in Arumeru, Babati, and Mvomero districts, respectively. A total of 125 dairy goat farmers were interviewed. A holistic approach of both quantitative and qualitative research methods was used to study the perceptions of farmers. More milk yield, sale of breeding stock and manure were the highest ranked reasons for keeping dairy goats. The reasons were coherent to the production systems. The three most preferred traits for improvement were milk yield, adaptability and twinning ability. These preferences were absolutely important in the context of the referred production system. Selection of replacement stock, animal identification and performance recording were the main challenges emphasised by farmers. The present study views these challenges as a result of knowledge gaps in animal breeding that require solutions. Based on result findings it is suggested that the milk yield and survival traits should be the primary dairy goat breeding goals. Generally, there are possibilities for developing sustainable dairy goat breeding programs in the surveyed areas given relevant breeding goals are incorporated. The design of simple and manageable dairy goat breeding schemes is necessary.

Heat stress is an important problem for dairy industry in many parts of the world owing to its adverse effects on productivity and profitability. Heat stress in dairy cattle is caused by an increase in core body temperature, which affects the fat production in the mammary gland. It reduces milk yield, dry matter intake, and alters the milk composition, such as fat, protein, lactose, and solids-not-fats percentages among others. Understanding the biological mechanisms of climatic adaptation, identifying and exploring signatures of selection, genomic diversity and identification of candidate genes for heat tolerance within indicine and taurine dairy breeds is an important progression toward breeding better dairy cattle adapted to changing climatic conditions of the tropics. Identifying breeds that are heat tolerant and their use in genetic improvement programs is crucial for improving dairy cattle productivity and profitability in the tropics. Genetic improvement for heat tolerance requires availability of genetic parameters, but these genetic parameters are currently missing in many tropical countries. In this article, we reviewed the HS effects on dairy cattle with regard to (1) physiological parameters; (2) milk yield and composition traits; and (3) milk and blood metabolites for dairy cattle reared in tropical countries. In addition, mitigation strategies such as physical modification of environment, nutritional, and genetic development of heat tolerant dairy cattle to prevent the adverse effects of HS on dairy cattle are discussed. In tropical climates, a more and cost-effective strategy to overcome HS effects is to genetically select more adaptable and heat tolerant breeds, use of crossbred animals for milk production, i.e., crosses between indicine breeds such as Gir, white fulani, N’Dama, Sahiwal or Boran to taurine breeds such as Holstein-Friesian, Jersey or Brown Swiss. The results of this review will contribute to policy formulations with regard to strategies for mitigating the effects of HS on dairy cattle in tropical countries.