This project was initiated to determine forage quality on the Eastern Las Animas/southern Otero/Eastern Pueblo county area of Southeastern Colorado. Specifically, we wanted to know this information to better assess optimum calving times in this area to best use forages and minimize supplemental feed. Because we suspected that many of the minerals included in standard mineral supplements were unnecessary in this area, we also hypothesized that a more targeted feed would both decrease supplementation costs and decrease the likelihood of mineral interactions and/or toxicities.
Different calving times were evaluated to determine the differences in mineral, protein and energy nutrition, and the risk of nutrient shortfalls and the ease with which these nutrient requirements could be met from the forage resources on the ranches in question. As expected, some nutrients could be met by the forage resources on the ranches in question; some nutrients were deficient throughout the year, some seasonally. Some were adequate throughout the year, though they are commonly included in commercially available supplements.
1. Develop a database of forage nutrient composition throughout the year to facilitate better management of nutrition and reproduction of cattle.
2. Develop a targeted supplementation program for cattle based on this database that will improve the nutritional status of animals while it decreases costs.
3. Make this database and supplementation program available for other producers in the region.
The project was scheduled to begin in the summer of 2002, but severe drought delayed the project for a year. Forage conditions were still so limited at the beginning of the sampling period that several of the ranches had not restocked after complete dispersal of livestock in 2002.
Samples were chosen to represent actual dietary intake by cattle. Producers sampled plants based on the species that had been grazed to get similar proportions of different plants in the diet. Mineral content measured included Calcium (Ca), Phosphorus (P), Magnesium (Mg), Sodium (Na), Potassium (K), Sulfur (S), Cobalt (Co), Copper (Cu), Iodine (I), Iron (Fe), Manganese (Mn), Selenium (Se), Zinc (Zn) and Molybdenum (Mo).
Forage samples showed unexpectedly low levels of available energy and protein, so much so that when used to predict performance, the predicted levels were lower than commonly observed by the cooperating ranchers. This was particularly noticeable in May through July. Several reasons may explain this difference. First, it is very difficult, even with the careful protocols used, to accurately select proportions of species and the plant parts taken by animals to mix their diets. Second, by air-drying the plants before shipping, some quality was lost. Third, since these plants were recovering from dry conditions, it may have affected the proportions of leaf and stem compared to more “normal” circumstances.
Mineral levels showed some chronic deficiencies, some seasonal deficiencies and some that were adequate at all times of the year. Those found to be sufficiently available at all times of the year included: Ca, S, Co, Fe and SE. Two of these elements, S and Se, were potential or confirmed toxic problems at times in this region, but are often supplied in commercial mineral supplements. Those deficient at all times of the year included: P, Mg, Na, Cu and Zn.
Iodine was limited from April through November. Manganese was limited during various times of the year; it seemed to follow no pattern based either on the forage growth rates or level of maturity, nor on the stage of production of the cows. It seems that a dormant mineral mix for August through November including K and I, one from December through April including K, and one from May through July including only I, in addition to those that are limited throughout the year, would be best.
BENEFITS OR IMPACTS OF AGRICULTURE
This type of targeted supplementation program should help people to reduce costs not only by removing unneeded minerals from their supplementation program, but also by evaluating their current production season and targeting calving times and breeding season to minimize the need for supplementation and decrease the risks of nutritionally induced reproductive failure.
The producers cooperating in this study tried to find feed mills in the area to produce these custom mixes, and one producer has already changed this weaning date to better allow his animals to regain condition and sell the calves before forage quality dropped in the fall. In addition, two others looked at late calving dates to better match the cows’ requirements to the nutrient levels and risk in this environment. Producers at the meeting where these results were presented were interested in the ramifications of the findings on a practical level, and wondered when cattle will be on this type of supplementation program. When the program is fine-tuned and proved successful, with the educational programs planned, it is anticipated that a significant number of the producers with similar soils and vegetation will use it. We also anticipate other producers in areas with different soils or vegetation communities will implement similar forage testing to develop their own customized supplementation programs.
RECOMMENDATIONS OR NEW HYPOTHESES
It is important to emphasize that the results of this project are applicable for producers in this climatic zone with soils derived from similar parent material and with plants of the same species. Areas with different conditions would likely have very different nutrient profiles, even if found in the same general vicinity. Other programs are available, such as the near infrared analysis of feces combined with the NUTBAL program developed by Texas A&M University and commonly used by the USDA-NRCS that cost less and may more accurately reflect actual energy and protein intakes, but lack the mineral analysis that this method employs. Because the method used in this case likely underestimates needs, using this method will likely provide adequate nutrition for the animals. However, it may be good to test a combination of the two methods whereby energy and protein are determined using near infrared analysis and minerals are determined with wet chemistry to see if it will be more economical or more accurate in providing for the animals’ needs throughout the year.
An educational workshop was conducted at one Soil Conversation District meeting in the region. A student was to present the details of the project at the High School Youth Forum of the Society for Range Management international meetings in Ft. Worth, Texas. Also planned was an extension publication about targeted supplementation and seasonal nutrient content of forages in southeast Colorado and a poster presentation for the 2006 international meeting of the Society for Range Management. An article was to be submitted to Rangelands, a publication of the Society for Range Management for general reading.