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CHAPTER 1. EQUATION OF REPRODUCTION. FOUR FACTORS. A = % of Herd Detected in Heat B = Inseminator Efficiency in % C = Herd’s Fertility Level in % D = Semen Fertility Level in %. % PREGNANCIES. Product of Four Factors A x B x C x D = % pregnancy
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CHAPTER 1 EQUATION OF REPRODUCTION
FOUR FACTORS • A = % of Herd Detected in Heat • B = Inseminator Efficiency in % • C = Herd’s Fertility Level in % • D = Semen Fertility Level in %
% PREGNANCIES • Product of Four Factors A x B x C x D = % pregnancy Total Can NOT be Larger Than the Smallest Percentage
FACTOR A • Recovery Interval Since Calving • Percent Heat Occurrence • Percent Cows in Heat that are Detected • Nutritional Adequacy Before and After Calving
FACTOR B • Inseminator’s Competency • Proper and Hygienic Handling of Semen • Placing Semen on Target
FACTOR C • Freedom From Disease • Herd Management Efficiency • Length of Postpartum Waiting Period • Postpartum Metabolic Disease • Change in Body Condition Score
FACTOR D • Capability of Bulls to Produce Quality Semen • Competency of Laboratory Processing Procedures • Frozen Semen Handling
Summary • 4 Variable & Independent Factors Determine Calving %
Question 1 • What is the equation of reproduction? • What factors make up the equation? A x B x C x D = % Pregnancy A = Herd members detected in heat and inseminated (%) B = Inseminator efficiency (%) C = Fertility level of the herd (%) D = Semen fertility level (%)
Question 2 • A really poor inseminator with an efficiency of only 60% was working in a herd with very high fertility. In fact the percentages of herd fertility, cows detected in heat and inseminated, and semen fertility were all in the 90’s. Without needing to know the exact figures for these factors you can tell that the percentage of pregnancies resulting from A.I. during this time will not exceed a certain upper limit. • What is it? 60%
Question 3 • The fertility level in herd X was 90%, but because of poor heat observation techniques, only 65% of the cows were detected in standing heat and inseminated. The bull semen had a fertility rating of 90%. Inseminator efficiency was 90%. • What is the percentage of pregnancies resulting from A.I. during this time period? 65% x 90% x 90% x 90%= 47.39%