The traditional practice on beef cow-calf ranches in the high desert region of Eastern Oregon has been to breed the cows to calve in the Spring months. Interest has been growing recently in the practice of Fall-calving; that is, breeding cows to calve in the months of October and November. The Squaw Butte Experiment Station at Burns, Oregon, began a Fall-calving program with part of their range beef herd several years ago. They found that climatic conditions are generally more favorable for calving in the Fall, resulting in higher weaned-calf percentages. Calves from both Spring and Fall-calving herds were weaned in late Summer, with Fall calves averaging around 500 pounds compared with 330 pounds for the Spring calves. There was little doubt about the biological feasibility of the Fall-calving practice in that area, but its economic feasibility was somewhat in question. The purpose of this research was to analyze the economic aspects of Fall-calving and determine what are the most important factors in deciding its economic feasibility. A linear programming model was developed for comparing Fall and Spring-calving systems under different conditions. The model was designed to maximize net returns to labor, management and fixed resources in the beef enterprise. This model took account of range forage utilization patterns. Solutions from the model indicated that Spring-calving systems may have slightly higher net returns than Fall-calving because of two main differences: (1) the lighter Spring-born calves bring a higher average price per cwt. , and (2) the Fall-calving herd requires about 1500 pounds more Winter hay than cows in the Spring-calving herd. An algebraic relationship was found between calf price differentials and the price of meadow hay, which would equate the net return values for Spring and Fall-calving systems. With an expected differential of $2. 95, between the average prices of calves sold from the Spring and Fall-calving herds, it was found that a price as low as $14.12 per ton of meadow hay would be needed to equate the net returns of a Fall-calving system with those of a Spring-calving system (with calf sales on September 1). Labor costs were not included in the model, but the ranch operator's labor situation may well be the most important element in his decision to go with Fall rather than Spring calving. The main difference is in the times of the year that labor is needed. The Fall-calving system needs more labor in the Fall, and the Spring-calving system needs even more in the Spring. / Graduation date: 1972

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Selection differentials and selection indices in retrospect were calculated to determine the relative emphasis placed on production and type traits through bull selection. Indices in retrospect including only production traits indicated that, for Holsteins, fat yield was the trait most heavily selected for between 1978 and 1987, followed by protein percent and then milk yield. Fat percent and protein yield had negative index weights throughout the nine year period. In Ayrshires, similar weights were observed except that milk yield index weights were negative throughout the nine year period. It was found that the relative weight placed on type was small and did not affect the relative weights place on production traits. Within Holsteins, differences in bull selection when multiple services were required to successfully service a cow indicated that selection for overall size was reduced in later services. Within Ayrshires, there were no differences in any production or type trait within multiple services.

Graduation date: 1980

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Call number: LD2668 .T4 1956 H86 / Master of Science

Call number: LD2668 .T4 1963 S66 / Master of Science