S. M. Robertson, T. Atkinson, M. A. Friend, M. B. Allworth, and G. Refshauge
Goat meat production is an expanding industry in Australia. However, there is limited data quantifying the levels of reproductive performance, particularly under extensively grazed rangeland conditions, which would inform interventions to improve performance. This review aimed to quantify the levels of reproduction, time and causes of reproductive wastage in goats. It considers the levels of fertility, fecundity, embryonic loss, fetal loss and post-natal survival reported under Australian conditions, and comparisons are made with international reports. Key management factors that may contribute to reproductive performance include breed, seasonality, nutritional conditions, and weather conditions at kidding. While goats are potentially prolific breeders, in Australia, the variation in weaning rate (kids/doe joined) among properties is large (51–165%), although the causes of this variation are not well defined. Generally, conception and kidding rates are high, although fetal loss associated with undernutrition is more likely in goats than sheep. As with sheep, perinatal losses are generally the largest source of wastage, with an average 20% kid mortality, but this level is influenced by litter size and appears to be higher under extensive rangeland systems. The causes of perinatal kid loss under Australian conditions are similar to those in sheep, with starvation–mismothering–exposure and dystocia or stillbirth the key causes. Studies are needed to accurately quantify the level and causes of reproductive wastage in commercial herds, including a range of management situations, to enable effective interventions to be developed.
Additional keywords: conception, litter size, reproduction, survival.
Associate Editor for Reproduction
Prof. K.C. Lehloenya is Associate Professor in the Department of Agriculture, University of Zululand, KwaZulu-Natal province, South Africa. She teaches various physiology and animal science subjects. To date, she supervised 16 postgraduate students to completion in reproduction and production physiology. Her specialization is in reproductive physiology and utilization of assisted reproduction technologies in farm animals to speed up the genetic progress and conservation of valuable genetic material. She is currently focused on combining specific nutrients (antioxidants) and molecular biology to improve livestock production using assisted reproductive technologies such as estrous synchronization, artificial insemination, in vitro embryo production and gametes cryopreservation. She visited and collaborated with international researchers from University of Florida (USA), INIA (Spanish National Institute for Agricultural and Food Research and Technology, Spain), AGRIS (Agricultural Research Agency of Sardinia, Italy). She authored and co-authored numerous papers on in vitro fertilization, estrous synchronization, multiple ovulation and embryo transfer, semen quality and cryopreservation.
Associate Editor for Reproduction
Nancy H. Ing, D.V.M., Ph.D. is a professor in the Department of Animal Science at Texas A&M University in the U.S.A. Texas A&M University is located in central Texas and has 68,000 students and is the 4th ranked veterinary college in the country (out of 30). Prairie View A&M University, 40 miles to the south, is home to the International Goat Research Center. Current research interests are:
The importance of the first area is that the RNAs may provide a novel assay relating to fertility and the non-coding RNAs are likely to regulate gene expression in the early embryo. The importance of the second area is that stress is increasing for animals and glucocorticoids, whether endogenous or given for medical reasons, rapidly but transiently impair steroidogenesis, resulting in periods of subfertility. For these studies, she has used goats, stallions and, most recently, honey bees and cattle. Previously, her research focused on estradiol’s stabilization of estrogen receptor alpha mRNA in the sheep uterus. She’s published 52 peer-reviewed research papers, nine book chapters, and 51 abstracts.
Production Systems and Sustainability
Reduced survival of lambs from maiden ewes exposed to mature ewes pre-lambing
S.M. Robertson, M.B. Allworth, M.A. Friend
Vol. 151, p11–15
The suboptimal survival of new-born lambs is a major source of reproductive inefficiency, is often lower in maiden (first-lambing) compared with multiparous ewes, and this may be associated with poor maternal behaviour due to inexperience. This study examined whether the survival of lambs from maiden ewes could be increased by exposing maiden ewes to multiparous lambing ewes in the month before lambing. Pregnant maiden Merino ewes (n = 446) which had been mated at 18 months of age were allocated to three replicates of two treatments.
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