Selection of alternative forage cultivars for high-Andean dairy systems: Genotype × environment stability, multicriteria desirability, and predictive models along an altitudinal gradient in the northern highlands of Peru

Abstract

The decline of the ryegrass–white clover swards that underpin smallholder dairying in the northern Peruvian Andes has widened a persistent dry-season feed gap. We evaluated the agronomic and nutritional performance of eleven alternative forage cultivars across three altitudinal zones (AZ I, 2300–2800; AZ II, 2801–3300; AZ III, 3301–3800 m.a.s.l.) in Santa Cruz, Cajamarca, Peru, over one production year, in a randomized complete block design with three blocks per zone. Because brassicas are harvested in a single cut and grasses and Lolium hybrids repeatedly, yield was analyzed separately by cutting regime. Among multiple-cut species the environment dominated yield variation (75.0% of the treatment sum of squares), with a moderate genotype × environment interaction (20.7%; p = 0.011), 'Shogun' was the most stable and productive hybrid (yield stability index = 5) and 'Delish' reached the highest desirability (D = 0.53). Brassicas peaked in the intermediate zone ('Groundhog', 10.87 t DM ha⁻¹) with no significant interaction (p = 0.51), and 'Green globe' ranked first on integrated merit (D = 0.47). Crude protein ranged from 6.33% to 19.75% and in vitro dry matter digestibility from 53.25% to 80.66%, increasing weakly but significantly with altitude (r = +0.29). Cultivar choice should therefore be specific to both altitudinal zone and functional group.