Abstract
The aim of the present study was to infer phenotypic trait expressions via mixed modeling considering both social and ecological continuous descriptors simultaneously. In this regard, we selected a challenging heterogeneous social-ecological environment, with focus on the rising megacity Bangalore, located in southern India. Dairy traits from 517 dairy cattle were recorded in 121 herds, equally distributed along a southern and a northern rural–urban gradient of Bangalore, distinguishing between urban, mixed, and rural areas. Repeated records from three visits per herd included production traits (daily milk yield in liter: MY), energy efficiency indicators (body condition score: BCS), cow wellbeing indicators (udder hygiene score: UddHS, upper leg hygiene score: ULHS, hock assessment score: HAS, rectal temperature in °C: RT), and health traits (locomotion score: LS, subclinical mastitis: SubMast). Associations between a continuous rural–urban gradient and phenotypic trait expressions were analyzed via mixed modeling, additionally considering “classic” environmental explanatory variables such as climatic conditions. MY and BCS were higher in urban than in rural areas, associated with reduced SubMast and improved hygiene scores for UddHS and ULHS. Scores for wellbeing indicators HAS and LS were unfavorable for cows in urban areas, indicating poor leg health conditions in that area. In rural areas, least-squares means for RT were quite large, probably due to the scarcity of shading and heat insulation of the barns. To the best of our knowledge, this is the first study disentangling phenotypic trait expressions in the context of social-ecological heterogeneity, contributing to a deeper understanding of physiological mechanisms underlying genotype by environment interactions.
Highlights
Traditional dairy cattle breeding focuses on improving milk yield or protein content, but with antagonistic impacts on functional traits such as fertility and health [1]
LP1 modeling for SSI was significant for milk yield (MY), body condition score (BCS), UddHS, ULHS, hock assessment score (HAS), and RT (p < 0.05)
Results from the present study showed an impact of SSI on a variety of important cow traits including productivity and functionality, such as MY, BCS, UddHS, ULHS, HAS, and RT
Summary
Traditional dairy cattle breeding focuses on improving milk yield or protein content, but with antagonistic impacts on functional traits such as fertility and health [1]. In addition to summer season or heat stress impacts, management characteristics [5], feeding systems [6], and heterogeneous grassland conditions [7] are associated with phenotypic trait expressions in harsh environments Social components such as farm management characteristics and human–animal relationships (as well as their interactions) influence susceptibility to disease infections [8], productivity, and animal behavior [9,10]. Manivannanan and Tripathi [11] found that urban dairy farms have developed a more efficient dairy management through better and wider social contacts, better availability of inputs (veterinary services, concentrate feed), and a high commercial orientation [12] Such economic motivation is the result of the union between the producer and the consumer. The social-ecological heterogeneity along rural–urban gradients in rising megacities might influence dairy production, a vital livestock sector in many regions of Asia and Africa [17,18]
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