Effect of Fish Oil Supplementation and Ratio of Alfalfa Hay versus Corn Silage on Holstein Bulls, Performance

A number of 36 Holstein young bulls (initial BW of 345±61 kg) were randomly assigned to 6 dietary treatments، following a 3 × 2 factorial arrangement، with Three concentrate levels of fish oil (0، 1. 5 and 3 % of DM) and 2 levels of alfalfa hay versus corn silage (10 and 20 % of alfalfa hay forage versus 20 and 10 % of corn silage) were used to investigate the effect of fish oil supplementation and the ratio of alfalfa hay to corn silage in the diet on animal performance. Bulls were fed TMR consisting of 30% forage and 70% concentrate mix on a DM basis. Average Daily Gain (ADG) was monthly assessed and dry mater intake evaluated every day prior to morning meals. The calves were slaughtered at the end of the experimental period (90 days) and the carcass characteristics recorded. Data were analysed through MIXED and GLM procedures of SAS software. There were no significant differences observed for performances، namely dry matter intake، average daily gain and feed intake as well as carcass traits as affected by interaction of fish oil and alfalfa hay level. The highest level of fish oil treatment negatively affected DMI (P < 0. 01)