Effects of Biuret and Lasalocid (Bovatec) Inclusion into a Effects of Biuret and Lasalocid (Bovatec) Inclusion into a Commercial Mineral Supplement on Growth Performance of Commercial Mineral Supplement on Growth Performance of Yearling Calves Grazing in the Kansas Flint Hills Yearling Calves Grazing in the Kansas Flint Hills

Inclusion of feed additives (i.e., ruminal modifiers or non-protein nitrogen) to mineral supplements may improve health and performance of grazing cattle. The objective of this experiment was to evaluate the inclusion of biuret with or without Bovatec (Zoetis, Parsippany, NJ) in a commercial mineral supplement on growth performance of year-ling beef calves grazing in the Kansas Flint Hills. Over a 2-year period, 742 crossbred steers [initial body weight (BW): 655 ± 52.2 lb] were randomly assigned to one of three mineral treatments (i.e., control, biuret, biuret + Bovatec). Mineral treatments were randomized into one of 18 pastures, with six pastures per mineral treatment. Steers grazed from May to August for a total of 90 days. Mineral tubs were weighed weekly to determine mineral consumption and refilled with respective mineral treatments to target a daily consumption of 4 oz per head per day. Mineral feeders were checked daily to estimate the number of days until an individual feeder was empty (days-to-empty). Total BW gains, average daily gains (ADG), and mineral consumption did not differ ( P ≥ 0.15) among mineral treatments; however, final BW were greater ( P ≤ 0.03) for biuret and biuret + Bovatec mineral treatments compared with the control mineral treatment. Initially, biuret and biuret + Bovatec led to more days-to-empty than the control ( P ≤ 0.05)


Effects of Biuret and Lasalocid (Bovatec) Inclusion into a Commercial Mineral Effects of Biuret and Lasalocid (Bovatec) Inclusion into a Commercial Mineral
were randomly assigned to one of three mineral treatments (i.e., control, biuret, biuret + Bovatec). Mineral treatments were randomized into one of 18 pastures, with six pastures per mineral treatment. Steers grazed from May to August for a total of 90 days. Mineral tubs were weighed weekly to determine mineral consumption and refilled with respective mineral treatments to target a daily consumption of 4 oz per head per day. Mineral feeders were checked daily to estimate the number of days until an individual feeder was empty (days-to-empty). Total BW gains, average daily gains (ADG), and mineral consumption did not differ (P ≥ 0.15) among mineral treatments; however, final BW were greater (P ≤ 0.03) for biuret and biuret + Bovatec mineral treatments compared with the control mineral treatment. Initially, biuret and biuret + Bovatec led to more days-to-empty than the control (P ≤ 0.05), but these differences disappeared by week 8.

Introduction
Mineral supplementation to cattle grazing in the Kansas Flint Hills may improve growth performance and overall profitability. A possible way to improve overall productivity of grazing cattle is through the addition of ruminal modifiers (lasalocid) or non-protein nitrogen (NPN) in mineral supplements. The objective of this experiment was to measure the effects of NPN (biuret) or NPN + ruminal modifier (biuret + lasalocid) inclusion in a commercial mineral supplement on growth performance of yearling beef calves grazing in the Kansas Flint Hills.

Experimental Procedures
Over a 2-year period, 742 crossbred steers (initial BW 655 ± 52.2 lb) previously backgrounded at the Kansas State Beef Stocker Unit were used to evaluate the effects of three mineral supplementation strategies on growth performance of yearling grazing cattle. Steers were purchased in Texas and Nebraska and randomly assigned to one of 18 pastures. Pastures were randomly assigned to one of three mineral treatments consisting of a basal supplement (control), a basal supplement with biuret and a basal supplement with biuret and Bovatec (Zoetis, Parsippany, NJ). Biuret was included in the supplement at 300 lb/ton dry matter (DM) basis to provide 0.6 oz per day of biuret when mineral was consumed at 4 oz per head daily. Bovatec was included in the supplement at 15.50 lb/ton DM basis to provide 180 mg/head/day lasalocid when mineral was consumed at 4 oz per head daily. An identical supplement feeder (Bullmaster; Mann Enterprises, Inc., Waterville, KS) was placed in each pasture.
Prior to grazing, steers were individually assigned a pasture tag, and treated for external (Standguard; Elanco, Greenfield, IN) and internal (Valbazen; Zoetis, Parsippany, NJ) parasites. In addition, steers were administered a growth promoting implant (Ralgro; Zoetis, Parsippany, NJ). Steers were grazed for 90 days from May to August at a targeted stocking density of 250 lb of live weight per acre. Immediately prior to turn out, pasture weights were measured using a pen scale. Following initial processing, steers were sorted and allocated to pastures over a 3-day period. At the completion of the grazing period, cattle were gathered, and pasture weights were immediately measured to determine average final BW, total BW gains, and ADG.
Mineral feeder flaps were initially folded up for approximately 2 weeks to allow cattle to locate the mineral. Flaps were unfolded, in the event of inclement weather, to prevent rain from getting into the mineral tubs. Following the two-week adaptation period, flaps were folded down for the remainder of the grazing season. Tubs were checked daily to monitor mineral consumption and determine days-to-empty. Mineral tubs were weighed each week to determine weekly mineral consumption. Mineral feeders were then refilled to target a mineral consumption of 4 oz/head/day for the following 7 days.

Results and Discussion
At the conclusion of the grazing period, total BW gains, ADG, and mineral consumption did not differ among treatments (P ≥ 0.15; Table 2). Final BW were greater (P ≤ 0.03; Table 2) for biuret and biuret + Bovatec mineral treatments compared with the control mineral treatment. Mineral feeders were monitored for mineral consumption daily and a visual estimate was made on the number of days until each mineral feeder was empty, this was expressed as days-to-empty. In weeks two and three of the grazing period, rate of mineral consumption (i.e., days-to-empty) was greater (P ≤ 0.01; Figure 1) for steers consuming the control mineral treatment compared with steers consuming the biuret or biuret + Bovatec mineral treatments. In addition, rate of mineral consumption during weeks 4, 5, 6, and 7 of the grazing period was greater (P ≤ 0.01; Figure 1) for the control compared with biuret + Bovatec. Overall, mineral consumption during the beginning of the grazing period was low; however, consumption increased so days-to-empty were 2 to 4 days by week 4 of the experiment. In late June, mineral consumption decreased, coinciding with elevated ambient temperatures.
After the elevated ambient temperatures, normal mineral consumption resumed, and all treatments were consistently between 2 to 4 days-to-empty at each observation.

Implications
These data were interpreted to suggest that the addition of biuret or biuret + Bovatec to commercial mineral supplement may improve growth performance of yearling beef cattle grazing in the Kansas Flint Hills.
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