Browsing Journal of Range Management, Volume 44, Number 6 (November 1991) by Subjects
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Nutrient intake of cattle on rotational and continuous grazing treatmentsMany benefits have been obtained from rotational grazing, including management flexibility and livestock distribution, but long-term positive effects on plant and animal production have been inconsistent. The purpose of this cast study was to investigate nutrient intake of animals in 2 production scale grazing, treatments. The study site was the Texas Experimental Ranch located in Throckmorton County, in the eastern portion of the Rolling Plains of Texas. Treatments were a 465-ha, 16-paddock, 1-herd, cell designed rotational grazing system (RG) stocked at a heavy rate (3.7 ha cow-1 yr-1) and a 248-ha continuously grazed (CG) treatment stocked at a moderate rate (6.2 ha cow-1 yr-1). Size of RG paddocks was varied to create different livestock densities to simulate rotational grazing at a 14 and 42 paddock level. Comparisons were made to determine the effect of type of grazing system (RG vs. CG) and the effect of livestock density within the RG system on nutrient intake. Nutrient intake of esophageally fistulated steers was determined by daily dosing them with ytterbium nitrate-labeled forage and collection of fecal samples plus collection of fistula extrusa samples for crude protein and in vitro organic matter digestibility determinations. The only difference caused by different livestock densities was a higher (P < 0.001) intake of forage crude protein in the simulated 42 paddock system. Nutrient intake of steers in the CG treatment was greater (P < 0.001) than those in the RG treatment. Differences between treatment were attributed primarily to differences in stocking rate rather than grazing system.
Technical Note: Surgical establishment of esophageal fistulae in suckling calvesEsophageal fistulae were established in five 34-day-old suckling calves by a modified surgical procedure used previously for sheep and goats. After skin incision, the esophagus was exposed by separating the brachiocephalicus and sternocephalicus muscles. A cannula was inserted into the esophagus after a longitudinal incision was made into the lumen of the esophagus. Sutures were not used in the esophagus. The calves recovered quickly with moderate post-operative swelling. We concluded that the surgical procedure was satisfactory and that diets were collected readily and without fistulae shrinkage.