 หัวเรื่อง:การผลิตโคนมฝูงขนาดใหญ่โดยกำหนดฤดูผสมพันธุ์ ผู้เขียน: Piphat Chanartaeparporn,  ดร.กัญจนะ มากวิจิตร์, ศาสตราจารย์ , นายบัณฑิต ธานินทร์ธราธาร, อาจารย์, ดร.ศรเทพ ธัมวาสร, ศาสตราจารย์ สื่อสิ่งพิมพ์:pdf AbstractThe seasonal block breeding system was carried out in a large dairy herd at the Dairy Farming Promotion Organization farm. An average of 275-325 kg. body weight from the total 80 heifers with age range of 18-30 months were selected in order to be tested in the 2 breeding seasons (hot wet and hot dry) for their first conception rate, A.I. index and cost per conception. For each season three groups of heifers were imposed by randomized design : (1) control, (2) imposed with PGF2?, and (3) imposed with Progestagen (SMB), and pregnancy diagnosis was determined by ultra sound sonography at 30 days from A.I. The results in each group of the hot wet season showed the conception rate to be 45.5%, 25.0% and 41.7%, A.I. index and cost per conception were 2.20, 4.00 and 2.40 with 24,735.20 baht, 24,746.54 baht and 24,222.91 baht per conception (p>0.05). Whereas in the hot dry breeding season resulted in conception rate were found to be 53.3%, 40.0% and 40.0%, A.I. index and cost per conception were 1.88, 2.5 and 2.50 with 23,561.92 baht, 23,934.30 baht (p<0.05) and 23,658.60 baht per conception for the 3 respective treatments |