Resumo

SIMON, L; LOPEZ, O  e  ALVAREZ, D. Evaluation of double-purpose Holstein x Zebu cows in grazing systems with trees: I. Primiparous. Pastos y Forrajes [online]. 2010, vol.33, n.1, pp. 1-1. ISSN 0864-0394.

With the objective of evaluating the productive and reproductive performance of different double purpose breed genotypes from the Holstein x Zebu crossings, 75 pregnant heifers were selected, 25 per group from genotypes Siboney (5/8 H x 3/8 Z), Mambí (¾ H x ¼ Z) and crossbred Siboney (5/8 H x 3/8 Z), in a completely randomized design, which made up a common group with access to the same management and feeding. The heifers were incorporated to reproduction after reaching 300 kg live weight and an average age of 28,6 months; they were managed in a dairy unit with trees, with a stocking rate of 1,6 animals/ha, and rotated in 28 paddocks. Pasture availability and daily offer of forages and supplements were measured monthly. Body condition was controlled and the thoracic perimeter was measured; milk production per cow was fortnightly checked, and the lactation duration and production and reproductive indicators were determined. The Mambí genotype was superior (P<0,01), with 1 840 kg/lactation of 288 days; while the best reproductive indicators (P<0,001) corresponded to crossbred Siboney, which parturition-parturition interval was 397 days, with 1,7 matings/pregnancy and a better body condition at the end of the dry season (2,55), which confirms that the feedstuffs supplied covered the nutritional requirements of primiparous cows without affecting their dairy potential. Crossbred Siboney was integrally the most outstanding genotype.

Palavras-chave : Genotypes; milk production; silvopastoral systems.

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