B. Murphy, P. Crosson, A.K. Kelly and R. Prendiville
The objectives of this experiment were to investigate (i) the influence of varying levels of concentrate supplementation during the grazing season, (ii) alternative finishing strategies for dairy bulls slaughtered at 15 mo of age and (iii) economic implications of these management strategies. Bulls were assigned to a 2 (level of concentrate supplementation during the grazing season: 1 kg [LA] and 2 kg [HA] dry matter [DM]/head daily) × 2 (finishing strategies: concentrates ad libitum group [AL] or grass silage ad libitum plus 5 kg DM of concentrates/head daily group [SC]) factorial arrangement of treatments. Average daily gain (ADG) during the grazing season was greater (P < 0.01) for HA than for LA. Consequently, HA bulls were 16 kg heavier at housing: 214 and 230 kg, respectively (P < 0.05). During the finishing period, ADG tended (P = 0.09) to be greater for LA than for HA. Carcass weight tended (P = 0.08) to be greater for HA than for LA. Fat score was greater for HA. Live weight at slaughter (P < 0.001) and carcass weight (P < 0.001) were 41 and 23 kg greater for AL than for SC, respectively. Conformation (P < 0.05) and fat score (P < 0.05) were greater for AL than for SC. The Grange Dairy Beef Systems Model simulated whole-farm system effects of the production systems. Net margin/head was greater for LA than for HA and greater for SC than for AL. Sensitivity analysis of finishing concentrate price, calf purchase price and beef price showed no re-ranking of the systems on a net margin basis. Although greater animal performance was observed from the higher plane of nutrition, overall profitability was lower.
L.F. Paludetti, K. Jordan, A.L. Kelly and D. Gleeson
In this study, the effect of storage temperature (2 or 4°C) on the composition of milk and microbiological load was investigated over 96 h. Milk samples were collected from farm bulk milk tanks after one complete milking and stored at 2 or 4°C over 96 h. Total bacterial count (TBC), psychrotrophic bacterial count (PBC) and proteolytic bacterial count (PROT) were affected by storage time and temperature and varied significantly between farms (P < 0.05). The levels of TBC, PBC and PROT bacterial count increased from 4.37 to 6.15 log cfu/mL, 4.34 to 6.44 log cfu/mL and 3.72 to 4.81 log cfu/mL, respectively, when the milk was stored for 96 h at 2°C. The milk samples stored at 4°C had higher increases in these bacterial counts after 72 h in comparison to milk samples stored at 2°C. The casein fraction content was lower in milk samples stored at 4°C, which could be due to high levels of PROT bacteria or enzyme activity in these samples. Milk stored for 96 h at 2°C has less impact on composition or processability parameters compared to milk stored at 4°C.
D. Johnston, D.A. Kenny, M. McGee, S.M. Waters, A.K. Kelly and B. Earley
The objectives of this study were (i) to characterise clinical health in dairy calves on an Irish research farm during the artificial calf-rearing period and (ii) to determine whether calves’ pre-weaning intakes and feeding behaviour, recorded by electronic calf feeders, changes in response to incidents of bovine respiratory disease (BRD). Holstein-Friesian (H-F) and Jersey (J) calves were fed by automatic milk replacer (MR) and concentrate feeders. Feeding behaviour, including MR consumption, drinking speed, number of rewarded and unrewarded visits to the feeder as well as concentrate consumption, was recorded by the feeders. A modified version of the Wisconsin calf health scoring criteria chart was used to score calves’ clinical measurements and identify incidences of BRD. Thus, 40% of calves were found to have at least one incident of BRD. Feeding behaviour was altered during incidents of BRD. The number of unrewarded visits to the feeder was reduced, by approximately four visits, for calves with BRD during the 3 d prior to the identification of BRD (P < 0.05) and tended to be reduced during the 7 d following the identification of BRD (P = 0.05), compared with healthy calves. Additionally, calves with BRD had a tendency for reduced net energy intake (approximately 8%) during the 3 d prior to the identification of BRD, compared with healthy calves. Therefore, calf feeding behavioural data, recorded by electronic feeders during the pre-weaning period, can indicate cases of BRD.