The Influence of Grazing Systems on the Performance and Diet of Yearling Cattle
Total Page：16
File Type：pdf, Size：1020Kb
AN ABSTRACT OF THE THESIS OF Timothy James Berry for the degree of Master of Science in Rangeland Resources presented on August 6, 1982 Title: The Influence Of Grazing Systems On The Performance And Diet Of Yearling Cattle. Redacted for Privacy Abstract approved: Marfin Vavra Research was conducted at the Starkey Experimental Forest and Range in northeastern Oregon to determine cattle performance, diet quality, botanical composition of forage ingested, and production and utilization among rest-rotation, season-long, and deferred rotation grazing systems. The grazing season lasted from June 20 to October 10 of each year. Cows equipped with esophageal fistulas were used to evaluate diet quality and diet botanical composition. Yearling heifers were used to evaluate livestock performance. The weight estimate method combined with a double sampling technique was used to estimate forage production. Utilization estimates were made by employing the use of the ocular-estimate-by-average- of-plants method. Grass was the most important forage class in cattle diets among the three systems. Grasses made up 67.7 percent of cattle diets on the season-long and rest-rotation grazing systems whendata were pooled across systems, periods, and years. Forbs and shrubs contributed 19.7 percent and 11.6 percent of the diet, respectively. Area collected and vegetation structure appear to influence the percent by weight of important species found in the diets of cattle among the systems. More grasses were consumed in the season-long system during early summer of 1979 than in the rest-rotation grazing system. Forb consumption decreased from 32.0 percent by weight to 8.1 percent as the grazing season advanced. Shrub consumption totalled only 13.4 and 17.5 percent during early summer and late summer, respectively. Crude protein, acid detergent fiber, lignin, and cellulose values of diet samples were not significantly different among the systems when data were pooled across years and periods. Although values for in vitro dry matter digestibility were different among the three systems, differences were not great enough to change animal performance. Livestock performance data trends were very consistent with diet quality data trends. However, livestock performance was signifi- cantly different among the grazing systems when data were pooled across years and periods even though there was little difference in diet quality among the systems. Average daily gains were 0.51, 0.61 and 0.65 kg for the rest-rotation, season-long, and deferred rotation grazing systems. Animals gained significantly more in deferred rotation than in the other two systems. Cattle gained significantly less in rest-rotation than cattle in season-long when data were pooled over years and periods. When spring rainfall was highest in 1980, production was greatest. Utilization was heaviest in the rest-rotation pasture when grazing pressure was heaviest due to animals remaining in this pasture throughout the grazing season. However, utilization totalled only 30 percent during 1980 in rest-rotation. The Influence of Grazing Systems on the Performance and Diet of Yearling Cattle by Timothy James Berry A THESIS submitted to Oregon State University in partial fulfillment of the requirements for the degree of Master of Science Completed August 6, 1982 Commencement June 1983 APPROVED: Redacted for Privacy Associpte Professor of RangeleUResources in charge of major Redacted for Privacy Head, lutnyeldnu Kesuurce ueparnmenL Redacted for Privacy Dean of Graduate nooi Date Thesis is presented Typed by Karen Duszynski for Timothy James Berry ACKNOWLEDGEMENTS The author wishes to express his gratitude to his major professor, Dr. Martin Vavra, for his understanding and his wisdom when dealing with matters related to this project. Decisions which the author thought would make or break the project, but which were considered minor in Dr. Vavra's eyes, were always dealt with by Dr. Vavra as if they were major decisions in his eyes too; such personal attention is commendable. For equipment, supplies, area to conduct research, and needed funds given to this project by the Pacific Northwest Forest and Range Experiment Station through the Range and Wildlife Habitat Laboratory in LaGrande and the Eastern Oregon Agriculture Research Center at Union, the author says thanks. Said funds provided the impetus of this project. Evelyn Bull served both as a friend and a technician during the conduction of research operations. Larry Bryant assisted in the coordination of this project with concurrent Meadow Creek projects. To all the Forest Service personnel who provided support to this study a warm thanks is extended. Without the staff of the Eastern Oregon Agriculture Experiment Station the offseason maintenance of resources used in this study would not have been possible and thus this project would not have been possible. So, to Chuck Ballard and his staff the author would like to express his appreciation for their contributions. Thanks also to Bev Raleigh for valuable laboratory analysis. I want to thank all members of my committee; Dr. Martin Vavra, Dr. John Buckhouse who substituted for Dr. Bill Krueger who did review the text, Dr. Harley Turner, and Dr. Robert L. Krahmer for critically reviewing this thesis. E. Leitz Inc. of Cincinnati, Ohio, was kind enough to loanme a microscope without which I would have been unable to finish my data collection. The trust they placed in me through the loan of the microscope is rare in today's society. I commend them for their support. Also, Steve Falkenberg of Eastern Kentucky University provided valuable assistance in the statistical analysis of thedata. To my friends and fellow graduate students who at times supported this project thoroughly and who helped me keep theproper perspective while contributing significantly to my professional and maturation development process, I appreciate it. Carol, my wife, provided support, love, editing advice, motivation, and understanding throughout this project. She spent time in Oregon to be near me while I continued work during the final year of this study. She deserves as much credit as anyone for seeing this thesis to the completion. To her I dedicate this thesis since it has been the culmination of the firstyear of our lives together. TABLE OF CONTENTS INTRODUCTION 1 LITERATURE REVIEW 4 The Effects of Grazing Systems on Livestock Production 7 Comprehensive Reviews of Grazing System Experiments 13 Grazing System Effects on Vegetation 19 Specialized Grazing System Benefits on the Vegetation 24 Deleterious Effects or No Effects on the Vegetation 25 Differential Response due to Grazing Management and Other Factors 27 Qualitative Evaluation of Forage 30 Components of Forage Quality 30 Factors Affecting Changes in Forage Quality 36 Techniques for Determining Chemical Composition and in vitro Dry Matter Digestibility 39 Sample Collection Problems 48 Microhistological Analysis for Botanical Composition of Fistula Samples 49 Estimation of Herbage Parameters 53 Herbage Weight Measurement Techniques 54 Utilization Measurement Techniques 61 STUDY AREA 67 Location 67 History of Use 70 Topography 71 Soils 72 Climate 74 Vegetation 76 METHODS Grazing and Livestock Management 84 Esophageal Fistula Collections 88 Laboratory Analysis 89 Production of Vegetation 91 Utilization of Vegetation 98 Statistical Analysis 99 RESULTS AND DISCUSSION 100 Botanical Analysis 100 Cattle diets in 1979 104 Cattle diets in 1980 108 Cattle diets in the deferred rotation pasture 111 Livestock Performance 111 Stocking Rate 111 Analysis of Variance 114 Diet Quality 119 Crude Protein 120 In Vitro Dry Matter Digestibility 122 Acid Detergent Fiber 123 Lignin 126 Cellulose 129 Production and Utilization 131 SUMMARY AND CONCLUSIONS 135 Botanical Analysis 136 Livestock Performance 138 Stocking Rate 138 Analysis of Variance 138 Diet Quality 140 Production and Utilization 141 Conclusions 141 LITERATURE CITED 144 APPENDICES 167 LIST OF FIGURES Figure Page 1 Location of the study area. 68 2 Meadow Creek Study area. 69 3 Grazing treatment schedule for units one, four 85 and two. LIST OF TABLES Table Page 1 Review of grazing system studies comparing continuous and 16 specialized grazing systems from a livestock production standpoint. 2 Precipitation at headquarters of the Starkey Experimental 75 Forest and Range. 3 Percent relative canopy cover for the primary species 78 occurring on the grazing system pastures in 1976. 4 Occurrence of plant communities in Phase II of the 79 Meadow Creek Study Area. 5 AUM's of stocking pressure applied to each grazing 86 treatment. 6 Grazing periods and corresponding dates for 1979 and 1980. 87 7 Plant communities sampled for production and utilization 93 of vegetation. 8 The percent by weight of important species found in 101 cattle diets pooled across periods and grazing systems. 9 The percent by weight of important species found in 105 cattle diets pooled across years and grazing systems. 10 The percent by weight of important species found in cattle 107 diets under the rest-rotation (RR) and season-long (SL) grazing systems in 1979. 11 The percent by weight of important species found in cattle 109 diets under the rest-rotation (RR) and season-long (SL) grazing systems in 1979. 12 The percent by weight of important species found in cattle 112 diets under the deferred rotation grazing system during 1979 and 1980. 13 Observed areas utilized by livestock during 1979 and 1980 113 grazing seasons (hectares). List of Tables. Continued. Table Page 14 Average daily gain (kg) for cattle on the grazing 116 system pasture in 1979 and 1980. 15 Percent crude protein in diet samples by year, period, 121 and grazing system. 16 Percent in vitro dry matter digestibility in diet 124 samples by years, period, and grazing system. 17 Percent acid detergent fiber in diet samples by year, 125 period, and grazing system. 18 Percent lignin in diet samples by year, period, and 127 grazing system. 19 Percent cellulose in diet samples by year, period, and 130 grazing system. 20 Percent cellulose in diet samples pooled across periods.