Review/Oorsig Volume 22, Issue 02 - Page 13

Volume 22 • Issue 02 • 2018 The breeding season for the heifers will stretch over a period of three months (90 days) but the goal is to get 85% of the heifers pregnant in the first 42 days of the breeding season Ensure that there are enough fertile bulls (1:20) that are free of sexual diseases. Replacement heifers are ideal candidates for a synchronization and AI program that could lead to faster genetic progress and further shortening of the first breeding season. If synchronization and AI was not previously used, a uniform group of well- grown heifers is the perfect opportunity to start using this technology. The veterinarian will do a pregnancy diagnosis at the end of the 90 days breeding season. Only the heifers that became pregnant in the first 42 days of the breeding season will be diagnosed as pregnant. Only the heifers that became pregnant within the first two oestrum periods (42 days) are selected as replacement heifers. That is the most important selection criteria for a fertile breeding herd. There must be good supervision when heifers calve for the first time. This is one of the main reasons why only the heifers that became pregnant in the first 42 days are selected as replacement heifers. Good supervision and nutrient management for heifers from calving until after the second mating season is the key to success on a beef cattle farm. First Calving cows are weighed at the beginning of the second breeding season and should be a minimum of 85% of the mature cow weight. If they are underweight, effective supplementation should be given. The second breeding season lasts for 3 oestrus cycles or 63 days. The veterinarian will do pregnancy diagnosis 8 weeks after the end of the second breeding season. First calf cows that are now confirmed pregnant for the second time can now be managed with the mature cows in the same group. Five-year plan for optimal fertility and Herd Health • • • By mainly focusing on the selection and management of replacement beef heifers, farmers can build a highly fertile herd within 5 years. Individual heifer groups are managed according to a plan that starts when the heifers are weaned and lasts until they are confirmed pregnant for the second time by the veterinarian. This plan is repeated annually for each new group of replacement heifers, until the entire herd is replaced with the heifers selected and managed for fertility. Select heifers that became pregnant within the first 42 days of the breeding season YEAR 01 Grouped 4th Calf Cows Grouped 3rd Calf Cows Grouped 3rd Calf Cows Grouped 2nd Calf Cows Grouped 2nd Calf Cows Grouped 2nd Calf Cows Grouped 1st Calf Cows Grouped 1st Calf Cows Grouped 1st Calf Cows Grouped 1st Calf Cows Select heifers that became pregnant within the first 42 days of the breeding season Select heifers that became pregnant within the first 42 days of the breeding season Select heifers that became pregnant within the first 42 days of the breeding season Select heifers that became pregnant within the first 42 days of the breeding season YEAR 02 YEAR 03 YEAR 04 YEAR 05 The end goal is a herd where 85% of the cows become pregnant in a breeding season of 63 days with more than 60% of the cows that will calve in the first 21 days of the calving season 13