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Comparison of Feed Technologies for Backgrounding of Weaned Beef Calves
The use of feed technologies in supplements is a means to positively affect performance and health status of newly-weaned calves during backgrounding. Our objective was to evaluate the response of weaned calves to different feed technologies in a supplement (CP = 14.6%, TDN = 67%) to improve calf performance and mitigate the stress response observed during weaning and subsequent backgrounding period. At weaning 160 calves (227 + 2.5 kg) were stratification by BW, sex, and breed and were randomly allotted to 1 of 4 treatments (n = 40 calves/treatment): 1) supplemented without feed technologies or control (CON); 2) supplement with added chlortetracycline, 350 mg/d (CTC); 3) supplement with added Rumensin, 175 mg/d (RUM); 4) supplement with added Actigen®, 5 g/d (ACT). Calves were held in 1 of 4 drylot treatment pens (n = 40 calves/pen) for 7 d after weaning and offered ad libitum access to hay and 2.27 kg/d of supplement prior to placement in 1 of 32, 0.8-ha pastures (5 calves/pasture) for a total of 8 pastures/treatment and supplemented at 1.0% BW. Calf BW were collected on d 0, 1, 3, 7, 14, 50, 52, 55, 59, and 65. After 44 d on pasture, calves were placed on 2 trucks and transported for 24 h. Upon return, calves were placed in 4 pastures with hay and fed their respective supplements for 14 d. Data were analyzed by the MIXED procedure of SAS. The model included the main effect of treatment, pasture was the experimental unit. During the 7 d after weaning, BW change did not differ (P = 0.65, -0.53 kg/d) among treatments. Over the 50-d post-weaning period there was no difference (P = 0.20, 0.52 kg/d) in BW gain response among treatments. After transportation, 7- and 14-d BW change were least (P < 0.005) for ACT and CTC (0.04 and -0.13 kg/d) compared to CON and RUM (-0.64 and -0.48 kg/d). Feed cost of gain and profitability (P≥ 0.15, mean = $2.49/kg and $73.51) were not different among treatments. Use of feed technologies did not improve calf performance over CON during a backgrounding period and ACT was as effective as CTC or RUM during a post-transportation period.
Keywords: beef, backgrounding, supplement