Introduction to breeding in crossbred dual purpose heifers

Abstract

This study evaluated 21,667 observations of age (EI) and weight (PI) of introduction to service in heifers from 47 dual-purpose bovine herds, located in four areas of dry and humid tropical forest environments. Effects studied were those of geographic area (Laberinto, Perija, Costa Oriental and Sur del Lago); management system: traditional (ST) and improved (SM); breed predominance (Holstein, Brown Swiss, Brahman and Carora); season of birth and of introduction to service; birth weight (PN); and weaning age (ED) and weight (PD). Mean EI was 30.9 ± 5.9 m and was earlier (P < 0.001) in Laberinto and Perija than in the other regions, in SM than ST (27.3 ± 02 vs.31.6 ± 0.01 m), and in Brown Swiss and Brahman than in Holsteins (32.0 ± 01 m). Mean PI was 353.3 ± 31.9 kg and was heavier (P<0.001) in Laberinto to (383.4 ± 1.5 kg), in SM than ST (364.6± 1.0 vs. 349.7 ± 0.5 kg), and Holstein and Brown Swiss (354.3 ± 0.7 and 357.6 ± 1.2 kg). EI was related to PI and dependent on daily weight gain (GDP); 48% of the heifers had GDP of 251 to 350 g/d an only 9.2% gained > 350 g/d. A GDP of > 350 g/d resulted in the earliest EI (24.4 ± 0.4 m) and the heaviest PI (375.8 ± 1.8 kg). Birth and weaning in dry season delayed EI. Lower EI and higher PI during rainy season were related to grazing conditions. At ED of < 10 m or > 10 m, EI increased (29.2 ± 0.4 to 34.6 ± 0.4 m) and PI decreased (366.2 ± 2.0 to 358.6 ± 2.0 kg); while in heifers with PD < 180 and > 180 kg, EI was 29.9 ± 0.2 and 27.8 ± 0.2 m, and PI was 353.5 ± 0.9 and 359.1 ± 1.1 kg (P<0.001). Adequate feeding management improved EI and PI results.