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

Heifer calves (n = 102) were used to evaluate the effect of once- or twice-daily feeding on growth, behavior, and economics of calves in an organic group management 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 Central 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, Montbéliarde, and Viking Red (selected for high production), and crossbreds (n = 31) including combinations of Holsteins, Jersey, Normande, and Viking Red (selected for robustness). 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 consumption 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 analyzed 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 performance 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 1× (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 1×; 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.