Evaluation of reproductive traits and fertility patterns in Rohilkhandi goats using longitudinal mixed models

Abstract

Reproductive efficiency is a major determinant of productivity in goat production systems, as traits such as litter size, kidding interval and age at first kidding directly influence lifetime reproductive output. The present study evaluated reproductive performance in Rohilkhandi goats using longitudinal and multivariate statistical approaches. Data were obtained from 1240 does maintained under organized herd conditions, with reproductive records available for up to four consecutive parities. The traits analysed included age at kidding, body weight at kidding, litter size and kidding interval. Descriptive statistical analysis indicated relatively low variability in age-at-kidding traits across parities, with the mean age at first kidding recorded as 547.09±29.09 days. Body weight at kidding increased progressively with parity, ranging from 16.48±0.87 kg at first parity to 25.08±0.86 kg at fourth parity, reflecting normal physiological growth of does. Mean litter size increased slightly from 1.40±0.49 to 1.61±0.49 between the first and fourth parities, indicating gradual improvement in prolificacy. The overall mean kidding interval was 320.47±14.13 days, remaining within the biologically acceptable reproductive cycle for goats. Mixed model analysis revealed moderate repeatability for litter size (r = 0.24) but low repeatability for kidding interval (r = 0.11). Random regression analysis indicated an increasing trend in litter size across early parities with stabilization around the third to fourth parity. A moderate negative correlation between age at first kidding and average kidding interval (r = ?0.576) suggested that earlier reproductive maturity was associated with shorter reproductive intervals. Overall, reproductive efficiency in Rohilkhandi goats was influenced by parity, reproductive maturity and persistent environmental effects.