Estimation of repeatability of milk yield and reproductive traits of Alpine goats under an intensive system of production in Egypt

Abstract

Data of 390 records from 130 French Alpine does were used to estimate repeatability of milk yield and some reproductive traits. For the first, second and third parity, the average milk yields were 252, 495 and 572 kg, average lactation lengths 221, 253 and 257 days, average litter size 1.3, 1.6 and 1.7 kids per doe, average kidding interval 343, 366 and 361 days, and average pregnancy lengths 147, 151 and 151 days, respectively. Repeatability estimates calculated by the intra-class correlation method (ICCM) were 0.731 for milk yield, 0.321 for lactation length, 0.212 for kidding interval, 0.010 for litter size and 0.891 for pregnancy length. Estimates of repeatability calculated by regression of subsequent lactation on initial number (RSN) (for the second and third lactations based on the first lactation number) were 0.549 and 0.265 kg for milk yield, 0.719 and 0.504 days for lactation length, 0.40 and 0.10 days for kidding interval, 0.024 and 0.383 for litter size, and 0.682 and 0.554 for pregnancy length. Repeatability estimates calculated by the RSN method, using the third performance based on the second one were 0.583, 0.60, 0.382, 0.051 and 0.617 for milk yield, lactation length, kidding interval, litter size and pregnancy length, respectively.