Research from University of Nebraska may add a few more dollars to the pockets of cattlemen. According to some latest research from the “2012 Nebraska Beef Cattle Report” sorting fed cattle prior to feeding Zilmax has shown some beneficial effects on carcass traits.
Zilmax is an approved beta agonist that improves weight gains through repartitioning nutrients into lean muscle growth. It is approved for feeding at 7.56 g/ton for 20-40 days with a 3 day slaughter withdrawal. However, Zilmax is generally fed for 20 days followed by the 3 day withdrawal.
In previous research, feeding Zilmax reduces USDA choice grades about 10%. Other research has shown that by sorting pens of cattle fed Zilmax you can feed the cattle longer and another research report showed that profits for sorted cattle are greater than unsorted cattle due to overweight discounts.
In the latest research, pens of cattle were randomly sorted into 5 different treatments of which 2 of these were controls. The controls were both unsorted cattle: one fed Zilmax and the other not fed Zilmax. In the remaining three treatments all were fed Zilmax but the heaviest 20% of each treatment were identified at 1) the beginning, 2)100 days from harvest and 3) 50 days from harvest. These heavier cattle were marketed 28 days before the remainder of their pen mates were scheduled for shipment.
Typical results occurred when comparing differences of feeding Zilmax versus not fed such as increases in: ADG, F:G, body weight and Carcass ADG. An interesting result did occur between the unsorted and sorted Zilmax fed treatments; there was a significant difference in final body weight, an average increase of 67lbs. for the sorted cattle.
Sorting cattle fed Zilmax also affected carcass characteristics. Cattle that were sorted maintained a marbling score at or above the pen that was not fed Zilmax. (The marbling scores were in the middle to upper small range, low choice.)Thus, they did not drop that 10% in choice quality grades as seen in other trials. In addition, cattle that were fed Zilmax and sorted had a hot carcass weight of 61, 56 and 53lb. heavier than the non fed Zilmax treatment respectively. Back fat was unchanged between the sorted and non-fed Zilmax pen. One final note, sorting did not reduce the percentage of overweight carcasses when discounts were applied at 950 or 1,000lb. carcasses. This may have been due to the additional 14 days the sorted treatments were fed due to the weight sort.
With research continuing, the latest tools in the beef industry can be utilized even more effectively. Feedlots utilizing Zilmax may benefit by sorting before the Zilmax feeding period to improve carcass characteristics.
Source: Heather Larson
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