Effect of production system on the health and performance of Holstein bulls during their first summer

摘要

Holstein bull beef production is commonly an intensive ad libitum concentrate indoor system. However, systems involving a grazing period potentially offer a lower cost of production. The objective of this trial was to identify if a grazing period could be included in bull beef production. A 2 (season) x 4 (production system) factorial design experiment involving 112 Holstein bulls was undertaken. Season differed by either autumn born or spring born. The four production systems differed during the summer with treatments including: (1) housed with ad libitum access to concentrates and silage (HA); (2) grazed with ad libitum access to concentrates (GA); (3) grazed with 2 kg day~(-1) concentrates (G2); and (4) grazed with no concentrates (G). Grass based treatments (GA, G2 and G) were rotationally grazed in seven day paddocks from 26 May 2017. Bulls were weighed fortnightly and health was monitored visually, with the effectiveness of rumen temperature boluses evaluated for identifying ill health.