Assessment of Good Agricultural Practices (GAPs) on sustainability outcomes in TMR, hybrid and pasture based dairy farms in South Africa

Abstract

The South African dairy industry faces growing pressure to balance production efficiency with environmental, social, and economic sustainability goals. Good Agricultural Practices (GAPs), implemented through the Dairy Standard Agency (DSA) Code of Practice for Producers, provide a structured framework to promote sustainable outcomes across various farming systems. This study examined how geographic, operational, and institutional factors—including region, feed regime, herd size, support level, and auditor—influence DSA_GAP compliance and sustainability performance on 152 dairy farms representing the four main production regions. It also compared DSA_GAP Sustainability results with RISE 3.0 sustainability outcomes. Data from 152 DSA_GAP sustainability audits and 24 RISE 3.0 assessments conducted on South African dairy farms with herd sizes from 50 to over 1000 lactating cows across seven provinces, grouped into the four main milk-producing regions - Eastern Cape, KwaZulu-Natal, Northern Regions, and Western Cape- were analysed. Quantitative data were processed using SAS (version 9.4, 2025). Descriptive statistics and Spearman’s correlations were estimated, and general linear models were applied to determine factors influencing sustainability performance. Analyses used a significance threshold of P<0.05 to identify meaningful differences. Findings showed that regional context and support frameworks had the most significant impact on Good Agricultural Practice and sustainability outcomes. The results revealed notable regional differences (P < 0.05): the Western Cape consistently achieved the highest average DSA_GAP Sustainability scores (>80% compliance), driven by strong environmental and compliance performance, whereas the Northern Region showed consistently weaker performance (<80% compliance), particularly under hybrid feeding systems. Pasture-based systems predominated nationally, but herds using Total Mixed Ration (TMR) systems exhibited greater risk resilience and economic sustainability (P<0.05). Herd size significantly affected the overall DSA_GAP sustainability score (P< 0.05), with smaller herds performing worse than medium and large-scale operations. Farms with structured support from processors or extension. Services consistently scored significantly higher (P < 0.05) on overall DSA_GAP sustainability criteria compliance and on the compliance subtheme. Positive monotonic associations between DSA_GAP and RISE 3.0 themes, particularly Environmental–Material (ρ = 0.405; P = 0.050), Social Responsibility–Quality of Life (ρ = 0.466; P = 0.022), and Social Responsibility–Working Conditions (ρ = 0.411; P = 0.046)—indicated measurable alignment between compliance-focused and outcome-based sustainability frameworks. Overall, the study demonstrates that structured GAP implementation is positively associated with improved sustainability performance in the dairy industry, particularly when supported by institutional frameworks and region-specific management systems.