L.A. Pacheco

Length of the weaning period affects postweaning growth, health, and carcass merit of ranch-direct beef calves weaned during the fall

Introduction Bovine respiratory disease (BRD) is the most economically devastating feedlot disease. Risk factors associated with incidence of BRD include (1) stress associated with maternal separation, (2) stress associated with introduction to an unfamiliar environment, (3) poor intake associated with introduction of novel feedstuffs into the animal’s diet, (4) exposure to novel pathogens upon transport to a feeding facility and commingling with unfamiliar cattle, (5) inappropriately administered respiratory disease vaccination programs, and (6) poor response to respiratory disease vaccination programs. Management practices that are collectively referred to as preconditioning are thought to minimize damage to the beef carcass from the BRD complex.

Calf health and performance during receiving is not changed by fence-line preconditioning on flint hills range vs. drylot preconditioning

Introduction Ranch-of-origin preconditioning can improve the welfare and performance of beef calves by decreasing the stress associated with weaning, transport, diet change, and commingling with other calves. Preconditioning methods that involve pasture weaning coupled with maternal contact (i.e., fence-line weaning) have been promoted as possible best management practices for minimizing stress. Prior studies focused on performance and behavior during preconditioning on the ranch of origin. Little information has been published relating to carryover effects of fence-line preconditioning compared with conventional drylot preconditioning on performance and behavior during feedlot receiving.

Efficiency of early weaned beef calves is not improved by restricting feed intake during 84-day growing phase

Introduction Early weaning can be used by cow-calf producers to reduce stocking rates by 20% to 30% during drought. Ranchers may be reluctant to wean early because of reduced calf weights and reduced revenue compared with weaning calves at conventional ages. To avoid revenue shortfalls, calves can be retained and grown before selling; however, grain prices are currently at unprecedented levels. Feeding grain-based diets to calves less than 125 days of age has been associated with excessive fat accumulation early in the feeding period and decreased carcass weights. Conversely, several researchers have noted marked improvements in feed efficiency when grain-based finishing diets were limit-fed. High feed costs and early fat deposition may be attenuated by limit-feeding a grainbased diet to early weaned calves. Our goal was to measure performance and efficiency of lightweight, early weaned beef calves during an 84-day postweaning growing phase when feed intakes were varied to achieve targeted gains of 1, 2, or 3 lb/day.

Effects of corn steep liquor supplementation on intake and digestion of tallgrass prairie hay contaminated with sericea lespedeza

Prolific seed production, in combination with little or no grazing pressure, has contributed to the rapid spread of sericea lespedeza in the Flint Hills. Increasing grazing pressure on sericea lespedeza may reduce seed production and slow its advance; however, the presence of condensed tannins inhibit consumption by grazing animals. Reports have indicated that feed-grade polyethylene glycol may inhibit formation of tannin-protein complexes in the rumen, but beef producers have not widely adopted polyethylene glycol because, at the rates necessary to increase intake of sericea lespedeza, it is cost-prohibitive and disallowed by regulations. Therefore, identifying substances that are generally regarded as safe (GRAS) by the U.S. Food and Drug Administration, cost-effective, and that mitigate the consequences of consuming a diet high in tannins is advantageous. Such information could lead to a degree of biological control of this noxious weed using the most economically important grazer (i.e., beef cattle) in the Flint Hills.

Effects of corn steep liquor supplementation on voluntary selection of tallgrass prairie hay contaminated with sericea lespedeza and uncontaminated tallgrass prairie hay

Introduction Sericea lespedeza (Lespedeza cuneata) is classified as a noxious weed throughout the Great Plains. It produces copious amounts of seed annually and contains high levels of condensed tannins during much of the growing season, which deters grazing by large domestic herbivores. In Kansas alone, this plant infests approximately 600,000 acres of native range, reducing native grass production by up to 92%. Increased grazing pressure on sericea lespedeza by beef cattle may slow its spread and facilitate some measure of biological control. Feedstuffs or feed additives with tannin-binding properties may promote voluntary consumption of this plant by grazing beef cattle.

Spring burning of native tallgrass pastures influences diet composition of lactating and non-lactating beef cows

Introduction Diet selection is a dynamic process because of seasonal changes in animal and plant characteristics. Nutrient requirements of grazing animals are a function of physiological state; moreover, plant characteristics may be altered with prescribed spring burning of native rangelands. Prescribed spring burning is used to improve the average quality of pasture forage by removing old growth and making new plant growth more accessible to grazing cattle.

Sun-curing and harvest maturity impactsconcentration and protein-binding capacityof condensed tannins in sericea lespedeza(lespedeza cuneata)

Prolific seed production, in combination with little or no grazing pressure, has contributed to the rapid spread of sericea lespedeza on Kansas rangelands. Increasing grazing pressure on sericea lespedeza may reduce seed production and slow its advance; however, development of appropriate research models to study sericea lespedeza intake by ruminants has been slow. Tannin concentration in sericea lespedeza changes dramatically during drying and storage. Therefore, avoidance of sericea lespedeza by grazing livestock is not generally observed when sericea lespedeza is fed to livestock in the form of sun-cured hay. Little is known about how harvest maturity and sun-curing influence the concentration of condensed tannins in sericea lespedeza or the degree of protein-binding by condensed tannins over the course of an entire growing season. Such information could lead to more effective research models for the study of sericea lespedeza intake by ruminant livestock. Therefore, the objective of our study was to examine changes in condensed-tannin concentrations and in protein-binding capacity of condensed tannins throughout the growing season in both sun-cured and fresh sericea lespedeza.

Voluntary intake of prairie hay contaminatedwith sericea lespedeza (lespedeza cuneata) bybeef cows

Introduction Sericea lespedeza (Lespedeza cuneata) is a noxious weed that infests approximately 600,000 acres of native tallgrass range in the Kansas Flint Hills. Intake of sericea lespedeza by grazing beef cattle is poor due to the presence of condensed tannins in the plant. Condensed tannins reduce protein digestion by beef cattle and may decrease plant palatability because of their astringence.

Length of weaning period but not timingof vaccination affects feedlot finishingperformance and carcass characteristicsof fall-weaned, ranch-direct beef calves

Introduction Bovine respiratory disease decreases profitability associated with cattle feeding. The cost of respiratory disease includes death loss, expenses associated with treatment, and reduced growth performance. Respiratory disease also decreases carcass weights, USDA quality grade, and ribeye area of feedlot cattle. Decreased carcass weights, fat thickness, and ribeye area have been associated with treatment of apparent respiratory disease when compared to animals not treated, whereas reduced incidence of the disease resulted in improved carcass merit. Preshipment weaning and vaccination has been found not only to prepare calves for improved performance in feedlots, but also to reduce incidence and severity of respiratory disease.

Forage selection preferences of experienced cows and naïve heifers grazing native tallgrass range during winter

Experimental Procedures The study was conducted on 8 pastures (approximately 69 acres each) located at the Kansas State University Beef Stocker Unit. These native range pastures were dominated by big bluestem (Andropogon geradii) and little bluestem (Schizachyrium scoparium), which were grouped together for the purposes of microhistological analysis; sideoats grama (Bouteloua curtipendula); blue grama (Bouteloua gracillis); switchgrass (Panicum virgatum); indiangrass (Sorghastrum nutans); leadplant (Amorpha canescensi); heath aster (Symphyotrichum ericoides); dotted gayfeather (Liatris punctata); and purple prairie clover (Dalea purpurea). Pastures were grazed from February 21 to March 1, 2009.