Application of positive deviance concept to assess Amelioration strategies for environmental stresses on Smallholder dairy farms in Tanzania

Abstract

Heat load, feed scarcity and disease infections are prevalent environmental stresses (ES) which either limit or reduce productivity potential of dairy cattle in the tropics. Those prevalent ES impact negatively on production performance of dairy cattle and results in a loss of livelihood benefits from dairying. Among smallholders, a few farmers (positive deviant farms (PDs)) attain consistently outstanding dairy production performance. While majority (typical farms) attain poor performance and loose benefits from dairy cattle. However, literature generally associates outperformance of PDs with husbandry practices being deployed differently from those in typical farms. Empirical evidence is lacking on association of PDs with specific husbandry practices, disease infections, lactation and growth performance. The objective of this study was to contribute to high livelihood benefits from dairying by improving productivity through learning from PDs’ ameliorative husbandry practices under contrasting stressful production environments in Tanzania. The severity of heat load stress on dairy cattle was estimated by temperature-humidity index (THI). A sample of 794 from 3800 smallholder dairy farmers benefiting from the African Dairy Genetic Gains Project was used. Positive deviants were identified based on criteria of consistently outperforming typical farms (p<0.05) in five production performance indicator variables simultaneously: daily milk yield ≥6.32 L/cow/day, energy balance ≥0.35 Mcal NEL/d, age at first calving ≤1153.28 days, calving interval ≤633.68 days and disease-incidence density ≤12.75 per 100 animal-years at risk. The study used a twofactor nested design, with farms nested within the production environment classified as lowand high-stress. Results show that dairy cattle in low-stress environment were exposed to lower heat-stress levels (68.20±0.39 THI) while those in high-stress environment were exposed to mild to moderate heat-stress levels (77.29±0.39 THI). The application of Pareto-Optimality ranking technique complemented with multiple indicator-variable sorting isolated 3.4% PDs and were fairly distributed in low- (n=15) and high-stress environments (n=12). Results reveal significant variations (p<0.05) between PDs and typical farms. Dairy cattle in PDs consistently attained better production performance in low- and high-stress environments. The management practices that differentiated PDs from typical farms were provision of larger floor spacing (13.19±1.94 vs. 6.17±0.37 m2/animal) in high-stress, cattle upgrading, and increased investment in housing, fodder, water and professional health services. These practices can be associated with amelioration of feed scarcity, heat load stresses, and disease infections, and better animal welfare status, which enabled attainment of consistent higher productivity levels in PDs. Therefore, typical farmers should learn from PDs on how to apply husbandry practices effectively to ameliorate feed scarcity, disease infections and heat load stresses.