Nutritional strategies for growing cattle in the Southeastern United States

Cattle operations in the Southeastern United States are primarily cow-calf and stocker based and rely heavily on forage. As such, research regarding supplementation strategies that are specific to both the forage cultivars and management strategies that are common in the region are necessary for accurate nutritional recommendations. Additionally, further research is necessary to develop solutions to cope with the negative effects of fescue toxicosis that are common in the region. Therefore, the objectives of this dissertation are to examine supplementation strategies specific to growing cattle as well as to investigate methods of reducing ergot alkaloid intake. Corn gluten feed (CGF) is a common corn co-product that is used to supply supplemental energy and protein. Experiment 1 investigated the effect of supplementing CGF or corn to grazing cattle and found that in grazing situations, growing cattle that are supplemented with CGF have greater average daily gain (ADG) and feed efficiency compared to those supplemented with corn (P  0.03). This improvement in ADG was without changes in subcutaneous fat accretion (P = 0.87), as there were no differences among treatments in fat thickness at the 12th rib (P = 0.54). This improvement in growth and efficiency was thought to be due to differences in the digestibility of fiber in the rumen. Therefore, experiment 2 was designed to investigate the effect of corn or CGF supplementation on apparent total tract nutrient digestibility when cattle are fed a forage-based diet. However, the results from this experiment indicated that there were no changes in neutral detergent fiber digestibility (P > 0.19). In fact, heifers supplemented with corn at 0.25% BW had greater acid detergent fiber digestibility compared with those supplemented with corn at the same level (P = 0.05). Ultimately, this resulted in animals being supplemented with corn tending to have greater organic matter digestibility compared to those supplemented with CGF (P = 0.10). Therefore, the improvement in performance that is observed when grazing cattle are supplemented with CGF compared to corn does not seem to be due to improvements in fiber digestibility. Experiment 3 examined if prolonged storage of ensiled tall fescue would result in the degradation of ergot alkaloids to levels similar to that of hay. Surprisingly, there were no differences among hay or haylage samples for individual or total ergot alkaloids regardless of storage time. Ergovaline concentrations, however, declined after 30 d of storage and were similar throughout the remainder of the storage period. Although no differences were observed among treatments, the reduction of ergovaline concentrations after 30 d of storage indicate that short-term storage may help to reduce the negative effects of fescue toxicosis for the animals consuming it.