Tuyển tập các báo cáo nghiên cứu về bệnh học thý y được đăng trên tạp chí Acta Veterinaria Scandinavica cung cấp cho các bạn kiến thức về bệnh thú y đề tài: Reproductive performance of Norwegian cattle from 1985 to 2005: trends and seasonality. | Acta Veterinaria Scandinavica BioMed Central Research Open Access Reproductive performance of Norwegian cattle from 1985 to 2005 trends and seasonality Arne Ola Refsdal Address Geno AI and Breeding Hamar Norway Email Arne Ola Refsdal - Corresponding author Published 13 February 2007 Received 23 October 2006 . . r r . nftft-r An I- . Ift I I ft 1 -71-1 ft I A-t ft I- Accepted 13 February 2007 Acta Veterinaria Scandinavian 2007 49 5 doi 1751-0147-49-5 This article is available from http content 49 1 5 2007 Refsdal licensee BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License http licenses by which permits unrestricted use distribution and reproduction in any medium provided the original work is properly cited. Abstract Declining reproductive performance is a serious breeding concern in many countries. To reveal the situation in Norwegian cattle trends in reproductive performance were studied using insemination reports from 1985 to 2005 and data based on herd recording files from 1989 to 2005. The total number of first services was in 1985 declining to in 2005. The number of recorded herds and animals declined from to and to from 1989 to 2005 respectively. Sixty days non-return rate after single inseminations NR60 increased from in 1985 to in 2005 p and the number of services per inseminated animal NIA decreased from to p from 1985 to 2005. However return rates 0-3 days post insemination increased from 6 to 12 in the same period p . NR60 was higher and the RR0-3 was lower in the summer season compared to the winter season during the whole period. A fertility index FS has been calculated from the herd recording files each year from 1989 to 2005. The average FS-index did not show a significant trend and the calving interval was also .
