Browsing by Subject "dairy bulls"

The present experiment was conducted to study feed intake, growth and carcass characteristics of growing dairy bulls offered diets based on whole-crop barley silage with or without protein supplementation relative to a grass silage-based diet. A feeding experiment was conducted in the experimental barn of MTT Agrifood Research Finland in Ruukki starting in January 2012 and ending in February 2013. Four feeding treatments comprised in 28 Finnish Ayrshire and 8 Holstein bulls. The bulls were fed a total mixed ration (TMR) ad libitum. For feeding groups 1 – 3 TMR included whole-crop barley silage [600 g/kg dry matter (DM)] and rolled barley (400 g/kg DM). The bulls in group 1 (KV) were fed without protein supplementation. Group 2 (KVR) got rapeseed-based concentrate 620 g/animal/d. Group 3 (KVRU) got rapeseed plus urea –based concentrate 480 g/animal/d. Group 4 (N) were fed a TMR which included grass silage (600 g/kg DM) and rolled barley (400 g/kg DM) but no protein supplementation. In order that concentrate proportions were same in all treatments, groups 1 and 4 got in addition 500 g rolled barley/animal/d. Protein supplementation in KVR and KVRU treatments was balanced so that the total amount of the crude protein in the diet was equal in both treatments, and the protein balance in the rumen fulfilled the Finnish recommendation which is above -10 g/kg DM for growing cattle above 200 kg live weight. The whole-crop barley silage and grass silage used in the present experiment included 623 and 678 g digestible organic matter in kg DM, respectively. The data were subjected to analysis of variance using the SAS MIXED procedure. Differences between the dietary treatments were tested using three orthogonal contrasts: 1) N vs. others, 2) KV vs. KVR + KVRU, and 3) KVR vs. KVRU. The bulls were fed the experimental diets from 217 days of age to slaughter at 562 days of age. There were no significant differences in the total DM intake (kg DM/d) between treatments. Due to higher energy intake, the live weight gain g/d and carcass gain g/d of the bulls were faster in the N diet compared to the whole-crop diets (p<0,07 and p<0,03). Protein supplementation had no effects on growth performance among the whole-crop treatments even though in the KV diet PBV was below the Finnish recommendation. Treatments had no significant effect on the dressing proportion but the carcass conformation score and fat score of the N bulls were higher (p<0,06 and p<0,003) compared to the whole-crop bulls. There were no differences in the carcass traits among the whole-crop barley diets. The feed conversion rate (DM intake kg/live weight or carcass gain) of the bulls was better in the N diet than in the whole-crop diets, but protein supplementation had no effects on feed conversion rates. It can be concluded that replacing well digestible grass silage with whole-crop barley silage decreased the carcass gain of the bulls due to lower energy intake and poorer feed conversion rate. However, the fairly high carcass gain (618 g/d) of the wholecrop bulls indicates that grass silage could be totally replaced by whole-crop barley in the diet of dairy bulls. Protein supplementation had no effects on animal performance among the whole-crop treatments even though in the KV diet PBV was below the Finnish recommendation. This indicates that recommended PBV for growing cattle above 200 kg live weight could even be reduced without adverse effects on gain.