Growth, behavior, and economics of group-fed dairy calves fed once or twice daily in an organic production system

摘要

Heifer calves (n = 102) were used to evaluate the ef-fect of once- or twice-daily feeding on growth, behavior, and economics of calves in an organic group manage-ment system. Calves were assigned to replicate feeding groups of 10 in superhutches by birth order, during 2 seasons from September to December 2013 and March to May 2014 at the University of Minnesota West Cen-tral Research and Outreach Center, Morris. Calves in groups were the experimental unit. Breed groups of calves were Holsteins (n = 26), crossbreds (n = 45) including combinations Holsteins, Montbeliarde, and Viking Red (selected for high production), and crossbreds (n = 31) including combinations of Holsteins, Jersey, Normande, and Viking Red (selected for robust-ness). Treatment groups were once-daily feeding (1×) or twice-daily feeding (2×). Calves in both groups were fed 6 L per calf/daily of organic milk with 13% total solids and then weaned at 60 d when the group con-sumption averaged 0.91 kg/d of starter per calf. Body weight and hip height were recorded at birth, once a week, at weaning, and at 90 and 120 d of age. Hobo Pendant G loggers (Onset Computer Corp., Bourne, MA) were applied to the right rear leg of calves to measure total lying and standing time. Data were ana-lyzed using PROC MIXED of SAS (SAS Institute Inc., Cary, NC). Independent variables for analyses were the fixed effects of birth weight (co-variable), season of birth, and treatment group, along with replicate as a random effect. No significant differences were found between feeding groups for body weight, weight gain, average daily gain, hip height, or heart girth. For calves in 1 × and 2 × groups, respectively, weaning group per-formance was as follows: gain per day was 0.79 and 0.81 kg, weaning weight was 92.7 and 93.3 kg, and weaning hip height was 95.2 and 95.3 cm. Daily gain to 90 d was 0.85 and 0.85 kg, and daily gain to 120 d was 0.85 and 0.83 kg for 1× and 2× calves, respectively. For lying time, calves in groups l× (988 min/d) and 2× (995 min/d) did not differ. During the evening hours, 2× calves had lesser lying times (34 min/h for l×; 28 min/h for 2×) because they were fed at 1800 h every evening. The average cost per kilogram of gain for the 2× ($4.03/kg) calves was greater than that for the 1× ($3.56/kg) calves. In summary, group-fed calves fed once a day in an organic production system had similar average daily gains and body dimensions compared with calves fed twice a day. Our results indicated that there is no need for twice-daily milk feeding under the conditions of the present study.