Your heifers are genetically the best animals in your herd, so why wait another year to have them produce replacement heifer calves?
Synchronising your heifers for AI ensures they are ready on day one of mating, meaning they are more likely to get in calf early and then have more opportunities to get in calf. Heifers that go on to calve early, will get in calf earlier in coming seasons, leading to more milk production and a longer life in the herd.
The predominant options for heifer synchrony are: a single PG shot, a double PG shot, or a CIDR programme.
Single PG
A single PG programme requires heat detecting and artificial inseminating (AI) heifers for 7 days, then injecting any that have not come on heat with prostaglandin (PG), and then continuing to heat detect and AI for 5-7 days.
Double PG
A double PG programme consists of two shots of PG 11-14 days apart. Following the second PG, heifers are either observed for signs of heat and then AI performed over the next 5 days, or a double fixed-time AI can be performed at 72 and 96 hours after the second PG injection, then followed by observing for late cyclers over the next 2-3 days.
CIDR programme
CIDR heifer synchrony programmes involve CIDR application with a gonadotropin-releasing hormone (GNRH) injection on day 1, CIDR removal and a PG injection on day 7, and then fixed-time AI with a GNRH injection on day 9.
There are pros and cons for each option. First-service conception rates to PG programmes are lower than with a CIDR plan, but this is weighed up against an increased drug cost. However, a CIDR plan only requires 3 yardings and no heat detection (due to the fixed-time AI), whereas either single or double PG programmes require multiple yardings and daily heat detection and drafting for AI.
Regardless of which synchrony programme you choose, prepubertal heifers are one of the biggest reasons for a poor response to a heifer synchrony programme. It is essential that heifers have reached target weight and are already cycling in order to respond to a PG programme -well grown heifers will also respond better to a CIDR programme.
Speak to your local Vetlife veterinarian to discuss further the benefits that heifer synchrony could have for your herd.
Caroline Reid
Vetlife Wanaka
