Genotype by Environment Interaction in Hereford Cattle: II. Birth and Weaning Traits

Abstract

The birth and weaning performance of different lines of Hereford cattle were compared in the dissimilar climates of Brooksville, FL, and Miles City, MT, from 1961 through 1975. During phase 1 of the study, two unrelated lines (F 6 and M1) previously developed at the two respective stations were compared over an l 1-year period following a reciprocal exchange of cattle. Concurrently, a Florida derivative of MI cattle (F 4) was selected for performance in Florida; thus, a later comparison of related lines (F4 and M1) developed at the two locations (phase 2 of the study) was made possible. Line by location interactions were highly significant for all traits during both phases of the study. When results over the two phases were pooled, advantages for the local over introduced groups were 1.2 kg for birth weight, 58 g for daily gain, 13 kg for 205-day weight, 2.1 cm for body length, .5 units for condition score and 24.8 kg for annual production per cow. These results agree with previous indications from this study that genetic adaptation to the local environment is important in commercial beef cattle production and merits serious consideration in performance testing procedures , interregional exchange of seedstock and sources of semen used for artificial insemina-tion. (