Feeding programs and feed ingredients that maximize calf growth rate add to a dairy’s profitability through both reduced feed costs and lifetime days open. Phytogenic feed additives, derived from plant extracts, offer a potential means of supporting feed intake and calf growth. A field trial was conducted at a commercial “calf ranch” near Atwater California in the summer and fall of 2014. Calf growth was compared between those that consumed a standard calf starter with those that received the same diet with a phytogenic product, Digestrom Calf (Biomin Inc.) Holstein heifer calves were individually housed. To accommodate farm labor, calves were fed calf starter with or without Digestarom Calf as a group based upon calving date. Calves were fed a calf milk replacer (26% CP, 11% CF) and a calf starter (18% CP, 4.4% CF) either containing or not containing Digestarom Calf. Calves were fed between 72 and 78 d. Weight and height were measured at weaning. During the trial, morbidity, both in the form of scours and respiratory issues, was recorded for each set of calves. There were no apparent starting date effects and data from all groups were combined and a simple t-test for differences was conducted. Treatments for scours or respiratory diseases were analyzed using Chi-squared differences; results are in Table 1. Those calves supplemented with the phytogenic product, Digestarom, had greater average daily gain and hip height. Table 1. Growth and recorded health incidences among preweaned calves in a commercial setting

Treatment	Calves (no.)	Average days fed (no.)	Initial wt (kg)	Final wt (kg)	ADG (kg)	Hip height	Scours (%)	Pneumonia (%)
Control	50	73.7	38.5	80.3a	0.57a	92.5a	60.0c	28.6e
Digestarom	115	72.0	38.2	84.0b	0.64b	95.0b	42.5d	18.4f

^abMeans in the same column differ (P = 0.0002). ^cdMeans in the same column did not differ (P = 0.1352). ^efMeans in the same column differ (P = 0.0732).