Feeding strategies for rearing replacement heifers in small-scale dairy production systems in the highlands of Central Mexico.

The growth of Holstein heifers in the campesino dairy systems in the highlands of Mexico was evaluated in three feeding strategies. Thirty-three heifers from 11 farmers, grouped according to strategy, were weighed every 14 days for 28 weeks. The live weight change over each 14-day period was estimated by individually regressing live weight over period, taking the regression coefficient as an unbiased estimate of live weight change. Regression coefficients were analysed as a randomized design with feeding strategies as treatments. Strategies were as follows: S1: grazed or cut pasture all year, maize silage and maize straw in the dry season, and 1.0-1.5 kg concentrate/heifer per day. S2: maize straw in the dry season, cut pasture forage, grazing of native grass, weeds from maize fields, and 1.0-1.5 kg concentrate/heifer per day. S3: maize straw in the dry season, grazed native grasses and weeds in the rainy season. Live weight gains were: S1, 0.511 kg/heifer per day; S2, 0.271 kg/heifer per day; and S3, 0.252 kg/heifer per day. Despite the better gains in S1, they are 24% below recommendations, arriving to service at 20 months of age. Not rearing their replacements may be a better alternative for campesino farmers under current economic conditions.