Response to hormonal treatment and conception rates of Sahiwal cows subjected to fixed time artificial insemination in pastoral dairy systems.

This study aimed at determining factors influencing response of Sahiwal cows/heifers to fixed time artificial insemination protocol in pastoral systems in Kenya. Available cows/heifers were inspected for conformity to Sahiwal breed characteristics, parity, body condition score, and subsequently rectal palpation to determine pregnancy status, ovarian structures, and estimated ovarian diameter. Consequently, these animals were injected with 100 µg of gonadotrophin-releasing hormone.

Genetic parameters for test-day milk yield, lactation persistency, and fertility in low-, medium-, and high-production systems in Kenya.

Genetic parameters for test-day milk yield, lactation persistency, and age at first calving (as a fertility trait) were estimated for the first 4 lactations in multiple-breed dairy cows in low-, medium-, and high-production systems in Kenya. Data included 223,285 test-day milk yield records from 11,450 cows calving from 1990 to 2015 in 148 herds. A multivariate random regression model was used to estimate variance and covariance components.

Estimation of genetic parameters for milk and fertility traits within and between low, medium and high dairy production systems in Kenya to account for genotype-by-environment interaction.

Dairy records from the Dairy Recording Service of Kenya were classified into low, medium and high production systems based on mean 305-day milk yield using the K-means clustering method. Milk and fertility records were then analysed to develop genetic evaluation systems accounting for genotype-by-environment interaction between the production systems. Data comprised 26,638 lactation yield, 3,505 fat yield, 9,235 age at first calving and 17,870 calving interval records from 12,631 cows which were descendants of 2,554 sires and 8,433 dams.

Breeding objectives for indigenous chicken: model development and application to different production systems.

A bio-economic model was developed to evaluate the utilisation of indigenous chickens (IC) under different production systems accounting for the risk attitude of the farmers. The model classified the production systems into three categories based on the level of management: free-range system (FRS), where chickens were left to scavenge for feed resources with no supplementation and healthcare; intensive system (IS), where the chickens were permanently confined and supplied with rationed feed and healthcare; and semi-intensive system (SIS), a hybrid of FRS and IS, where the chickens were partially confined, supplemented with rationed feeds, provided with healthcare and allowed to scavenge within the homestead or in runs. The model allows prediction of the live weights and feed intake at different stages in the life cycle of the IC and can compute the profitability of each production system using both traditional and risk-rated profit models.

Application of risk-rated profit model functions in estimation of economic values for indigenous chicken breeding.

The economic values for productive (egg number, average daily gain, live weight, and mature weight) and functional (fertility, hatchability, broodiness, survival rate, feed intake, and egg weight) traits were derived for three production systems utilizing indigenous chicken in Kenya. The production systems considered were free-range, semi-intensive, and intensive system and were evaluated based on fixed flock size and fixed feed resource production circumstances. A bio-economic model that combined potential performances, feeding strategies, optimum culling strategies, farmer's preferences and accounted for imperfect knowledge concerning risk attitude of farmers and economic dynamics was employed to derive risk-rated economic values.