Co-Authors:
Weller, J.I., Department of Cattle and Genetics, Institute of Animal Sciences, A.R.O., P.O. Box 6, Bet Dagan 50250, Israel
Abstract:
Investment in breeding is unique because genetic gains are eternal and cumulative. They are never "used up", and never "wear out". However, nearly all of the gain is transferred to the national economy. Very little stays with farmers or commercial breeders. Unlike genetic gains, costs are not cumulative. With a profit horizon of 20 years and a discount rate of 0.08, total discounted costs will equal total discounted gains if the value of the nominal annual genetic gains is 0.3 of the nominal annual costs. The rate of genetic gain for milk production in dairy cattle has been about 1% per year for the last 20 years. Since the 1950s, rates of genetic gain have increased due to better pedigree information, more traits recorded, more accurate recording, and better statistical methods. From the beginning of modern breeding programs, selection in dairy cattle focused on milk production. From 1985, breeding goals moved towards improving protein yield. In recent years, selection objectives were broadened to include "functional herdlife", fertility, and health traits. The main reasons behind this shift were quotas and/or price constraints, and increasing concerns associated with the deterioration of the health and fertility of dairy cows. Modern technology complements traditional breeding but does not replace it. To date, nearly all progress in animal breeding has been obtained by traditional trait-based methodology. There is no substitute for accurate data and pedigree recording.
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ניגודיות עדינה
מונוכרום
הדגשת קישורים
חסימת אנימציה
פונט קריא
סגור
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