Supplement intake behavior of heifers grazing late summer dryland pasture

Abstract

Two studies were conducted to evaluate supplement intake and intake behavior of Rumax BoviBox protein supplements. For both studies, individual supplement intake, time spent at the feeder, and frequency of visits was measured using a SmartFeed Pro self-feeder system. In study 1, we examined the effects of free choice loose mineral salt on protein block supplement intake behavior of first-calf heifers. Heifers were stratified by weight, and, within stratum, randomly allotted to one of two supplementation treatments: 1) free-choice access to protein block supplement (30% CP) with access to loose mineral and salt; and 2) free-choice access to protein block supplement (30% CP) with no access to loose mineral and salt for a 42-day performance study. Individual animal was considered the experimental unit. No differences were observed for total supplement intake or supplement intake expressed as grams per kg body weight (BW; P > 0.05). In summary, availability of loose mineral salt did not have an impact on protein block supplement intake. In study 2, we evaluated Rumax BoviBox versus Rumax BoviBox HM protein supplements on supplement intake, intake behavior, body weight (BW), and body condition score (BCS) change of yearling heifers grazing dryland pastures during late summer. Heifers (428 kg) were stratified by BW and within stratum randomly assigned to one of two supplementation treatments: 1) free-choice access to Rumax BoviBox protein block supplement (30% CP, 23% salt; n = 29); and 2) free-choice access to Rumax BoviBox HM high magnesium protein block supplement (28.7% CP, 23% salt; n = 30). Supplement intake rate (g x min -1) displayed a treatment effect (P < 0.01) indicating that heifers in the Rumax BoviBox treatment had lower intake rate compared to Rumax BoviBox HM supplemented heifers. In conclusion, there were only minor differences in intake behavior and animal performance observed in both trials.