By: John Maday, editor, Bovine Veterinarian
During this week’s Cattlemen’s College session at the Cattle Industry Convention in San Diego, Reinaldo Cooke, PhD, Oregon State University, outlined how trace mineral supplementation in gestating cows, perhaps above typically recommended levels, can benefit calf performance. Cooke’s research also indicates organic sources of key minerals might transfer to the gestating calf more efficiently than inorganic sources.
Cooke notes that while much remains to be learned about the effects of trace minerals, key elements such as cobalt, copper, manganese and zinc are known to be essential for fetal development, and the dam is the only source of those nutrients for the developing fetus. Also, research has shown that organic formulations of those minerals, which involve bonding the metal to an amino acid, can be more bioavailable than inorganic, or sulfate formulations, of the same minerals.
Cooke and his team set out to determine whether supplementing cows, which were not mineral deficient, would provide benefits to their calves, and whether organic formulations would provide a benefit over inorganic minerals. The researchers designed a trial with 84 pregnant cows, sorted into three treatment groups at the end of their second trimester of pregnancy. Treatments included controls receiving no trace mineral supplement, a group receiving inorganic supplements of cobalt, copper, manganese and zinc, and a group receiving organic formulations (Availa 4) of the same minerals.
Other than the mineral supplements, the rations were identical, and the control ration met accepted levels of trace minerals, meaning none of the cows were deficient. The researchers fed the three diets through the third trimester until calving. After calving, all the cows and calves were treated the same with inorganic trace mineral supplements.
At the initial tests as the cows came off rangeland grazing at the end of their second trimester of gestation none were deficient for the four critical trace minerals. Prior to calving, the researchers collected liver biopsies from cows and at calving collected liver samples from calves and samples from placentas.
In the cows prior to calving, liver cobalt concentrations were slightly higher in cows consuming the organic supplements, copper levels higher in cows receiving inorganic sources, manganese levels similar in both groups and zinc higher in cows receiving inorganic minerals. In the placenta samples, cows receiving the organic sources were somewhat higher for all four minerals. Cooke notes inorganic and organic sources improved trace-mineral status of cows versus controls, but the organic forms seemed to transfer better to the calves, which all came from the same AI sire.
Weaning weights averaged 519 pounds for calves from cows receiving the organic minerals versus 491 pounds for those from the group receiving the inorganic minerals. The calves from the organic-mineral group had a $70 per head advantage over controls at weaning while the inorganic-mineral group had a $32 per head advantage. The control groups, Cooke notes again, were not considered mineral deficient.
The researchers sent the calves to a grow lot following weaning and then to a finishing lot. During the growing period, 42 % of the control calves required BRD treatment, compared with 59 % of calves from inorganic-supplemented cows and 20 % of calves from cows receiving organic mineral supplements. Body weights at the end of the growing period averaged 774 pounds for controls, 790 pounds for the inorganic group and 823 for the organic-mineral group. At finishing, body weights averaged 1,428, 1,459 ad 1,496 pounds for the control, inorganic and organic groups respectively. BRD treatment rates during the finishing period were 0, 5.2 and 4.4 % for the control, inorganic and organic groups respectively.
The researchers concluded that the organic formulation of mineral supplements in cows decreased BRD in their calves during the critical receiving period, and that greater weaning weights for the calves from organic-mineral-supplemented cows were maintained through the finishing period.
Maybe, Cooke says, cow-calf producers should provide more trace minerals to cows than currently believed. He adds that supplementation during the first and second trimester probably would improve calf performance further, but the Oregon trial focused on supplementing during the third trimester due to the extensive range-production environment for early gestation cows and its limits on controlling mineral intake.