Abstract #T264

# T264
Effect of phytogenic feed supplements added to starter grain on weight gain and rumen development in Holstein calves.
H. A. Rossow1, K. Mitchell1, A. Johnson*1, B. Miller2, 1University of California Davis, Tulare, CA, 2Biomin America Inc, San Antonio, TX.

The goal of pre wean calf operations is to maximize rumen development and weight gain. Feed supplements that increase starter intake should also encourage rumen development and increase weight gain. The objective of this study was to compare rumen development and body weight gain in pre wean calves given 2 different starter supplements, phytogenic blend A (A) or phytogenic blend B (B) (Biomin, San Antonio, TX) or no supplement (Control) at a commercial calf ranch. One hundred twenty-four Holstein calves were randomly assigned to 1 of 3 treatments, Control, A or B, at 1 d of age. Control (nothing added), A or B were added to individual feed buckets at each feeding at the rate of 0.25 g/kg starter at AM and PM feedings. Both starter intake and milk intakes were assessed daily. Calves were weighed at enrollment and at weaning, and blood samples were collected from a subset of 38 calves and analyzed for glucose (Glu, mg/dL) and β-hydroxybutyrate levels (BHB, mmol/L) with Precision Extra blood meters (Abbott Diabetes Care, Inc., Alameda, CA) to assess rumen development. Weekly average DMI, milk intake, Glu and BHB were analyzed using the Mixed procedure of SAS (v. 9.4) with repeated measures by calf, fixed effects treatments and random effect week. Weekly average DMI (P < 0.01), BHB (P < 0.01) and Glu (P < 0.01) were different by week but not by treatment. However, weekly milk intake was less for group B (P < 0.05). Total DMI, initial bodyweight, final body weight and gain were analyzed using the Mixed procedure of SAS with repeated measures by calf, fixed effects hutch, sex, birthdate. There were no differences in initial bodyweight and effects of hutch, birthdate, or sex among treatments. Product B group was numerically greater in total DMI, gain, ADG and had faster rumen development indicated by overall higher BHBA values but differences were not significant among treatments. Therefore, supplementation with B decreased milk intake but calves maintained similar starter DMI, gain and ADG.

Key Words: phytogenic supplement, calf starter