Resumen

LOPEZ, Jenny  y  VACCARO, Lucia. Comportamiento productivo de cruces Holstein Friesian-cebú comparados con Pardo Suizo-cebú en sistemas de doble propósito en tres zonas de Venezuela. Zootecnia Trop. [online]. 2002, vol.20, n.3, pp.397-414. ISSN 0798-7269.

The purpose of the study was to compare the perforrnance of Holstein Friesian- zebu (HFx, n=3256) and Brown Swiss-zebu (PSx,n=2055) crossbred cows on 10 dual purpose farms in three regions of  Venezuela, with higher management levels in region 3 (Falcon) than in regions 1 or 2 (Guárico ). Linear models were used to analyze milk yield per lactation (MY). lactation length (LL), calving interval (CI), milk yield per day of calving interval (MY/CI), calf survival (SV) and calf weight (CW). adjusted to 4 months, including the effects of region (R:1,2.3); breed group (BG: l/2 HFx,≥5/8 HFx, ½ PSx,≥5/8 PSx); year of calving (Y:1989,.1998); season of calving (S:trimester 1,4); calving number (CN:1,≥2) and the interactions BG x R. BG x CN and BG x S.The adjusted means (± SE)were: MY: 1396±23 kg; LL:253±3 days; CI:460±3 days; MY/CI: 3.3±0,06 kg/day; SV:81,3±0,9% and CW:67,3±0,4 kg. BG significantly (P<0.01) affected MY, LL, IEP and SV, but not MY/CI or CW. The BG x R interaction was significant for MY, LL, CW (P<0,01), and CI (P<0,05). SV of the ≥5/8 HFx was lower than the other groups (P<0,01). independent of region. It was concluded that no BG had a clear productive superiority in regions 1 or 2, and that the advantage ofthe ≥5/8 HFx in MY in region 3 (12-15%,(P<0,01) was not reflected in higher MY/CI and was reduced by their lower SV.

Palabras clave : Crossbred cows; Holstein Friesian-zebu; Brown Swiss-zebu; productive performance; dual purpose.