Effect of feeding kelp on growth and profitability of group-fed dairy calves in an organic production system

Abstract Text: Heifer calves (n = 113) were used to evaluate the effect of feeding kelp on growth and economics of calves in an organic group management system.  Calves were assigned to replicate feeding groups of 10 in super hutches by birth order during two seasons from September to December 2012 and March to May 2013 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 (HO, n = 16) selected for high production, HO (n = 17) maintained at 1964 breed average level, crossbreds (n = 51) including combinations HO, Montbéliarde, and Swedish Red selected for high production, and crossbreds (n = 29) including combinations of HO, Jersey, Normande, and Swedish Red selected for robustness.  Treatment groups were 1) control calf starter (CS; 18% CP as-fed; CON), 2) CS plus 56.7 g kelp/calf daily (Kelp2), or 3) CS plus 113.4 g kelp/calf daily (Kelp4).  Calf groups were fed 1.5% DM solids of 13% total solids organic milk of birth weight once daily and then weaned at 60 d when the group consumption averaged 0.91 kg starter/calf daily.  Body weight and hip height were recorded at birth, once/wk, at weaning, and at 90 d of age.  Data were analyzed using PROC MIXED of SAS. Independent variables for analyses were the fixed effects of birth weight (co-variable), season of birth, breed group, treatment group, along with replicate as a random effect.   Calf group ADG to weaning and weaning BW were 0.67, 82.9; 0.63, 79.4 and 0.61, 78.4 kg for CON, Kelp2 and Kelp4, respectively (P < 0.10). Hip height at weaning were 93.8, 91.2 and 91.8 cm for CON, Kelp2 and Kelp4, respectively (P < 0.05). Daily gain to 90 d were 0.78, 0.74, and 0.68 kg for CON, Kelp2, and Kelp4 respectively, (P < 0.05).  Total costs (grain, health, and organic milk) to 90 d of age for calf groups were $2,660.20 for CON, $2,711.39 for Kelp2, and $2,718.42 for Kelp4; however, the cost per kilogram of gain was significantly higher (P < 0.05) for the Kelp4 ($4.16) group compared to the CON ($3.69) group.  In summary, calves fed a control calf starter had higher daily gains than calves fed high kelp calf starter rations. Feeding kelp in calf starter rations for organic dairy calves may not be economically justified. 

Keywords: calf starters, organic production, kelp