In the last two weeks I have fielded a lot of questions about breeding heifers and synchronising them. Everyone knows the importance of calving down heifers before 24 months and breeding them at adequate body weight at around 13-15 months. The average weight, depending on breed, should be around 330kgs.
This is undoubtedly an area where farmers can reduce expense by having heifers calving down early and breeding at the correct weight and age. There are several different management options as MSD (mating start date) approaches. Heifers should receive tail paint and observe for heat provided they are cycling. Heifers will be cycling, provided nutrition is correct and genetics are on their side. To enhance SR and to speed up the process, we often employ synchronisation techniques on the farm.
Before discussing synchronisation, we must look at the reproductive cycle to understand why we use certain agents. The most common question I get asked is about the bulling injection or prostaglandin (estrumate, lutalyse). This will bring heifers around or into heat only if they are cycling first and if there is an active functioning CL (corpus luteum) present in the average 21 day cycle.
Standard 21 day cycle
Day one: The egg is released.Day five: That follicle becomes a CL.Day 17: If the egg isn’t fertilised or animal has not become pregnant, the follicle will regress and the whole process begins again at day 21.So therefore prostaglandins (PGs) such as estrumate are only effective between day 5-17 generally and you will have up to 9-10 days of the cycle where giving them PGs has no effect on that cycle. This is where the strategic protocols have been developed to get heifers in heat using PGs. There are three options I apply on farms with heifers using PGs. Whichever one you use can be in relation to time and labour or cost. This should be done in consultation with your own vet.
Give the heifer two shots of PG 11 days apart and breed 48-72 hours after second injection at day 11 when showing signs of heat. I prefer to breed heifers that have been observed in heat as opposed to using fixed time AI with this protocol. However some people will use fixed time AI with this technique, but in my experience this yields lower conception rates.Give one shot of PG on day one and tail paint and breed any heifers seen in heat after first injection. Those not served after the first shot should be injected at day 11 again with a PG and breed on observed signs of heat 48-72hrs later. This is more labour intensive but less costly as you require less PG.Observe heat for seven days and AI heifers seen bulling in that period. At day seven, inject PG to heifers not seen bulling in first seven days and then breed them on signs of heat usually 48-72 hours later. This is less costly than the options outline above, but more labour intensive.By adopting these protocols, we allow more controlled breeding and even those heifers missed will be repeating at more regular intervals for the rest of the breeding season. Of course there are more sophisticated and expensive techniques; your own vet will help you manage these. The important message is if using prostaglandins, heifers must be cycling and they are only active when a functioning CL is present.
In the last two weeks I have fielded a lot of questions about breeding heifers and synchronising them. Everyone knows the importance of calving down heifers before 24 months and breeding them at adequate body weight at around 13-15 months. The average weight, depending on breed, should be around 330kgs.
This is undoubtedly an area where farmers can reduce expense by having heifers calving down early and breeding at the correct weight and age. There are several different management options as MSD (mating start date) approaches. Heifers should receive tail paint and observe for heat provided they are cycling. Heifers will be cycling, provided nutrition is correct and genetics are on their side. To enhance SR and to speed up the process, we often employ synchronisation techniques on the farm.
Before discussing synchronisation, we must look at the reproductive cycle to understand why we use certain agents. The most common question I get asked is about the bulling injection or prostaglandin (estrumate, lutalyse). This will bring heifers around or into heat only if they are cycling first and if there is an active functioning CL (corpus luteum) present in the average 21 day cycle.
Standard 21 day cycle
Day one: The egg is released.Day five: That follicle becomes a CL.Day 17: If the egg isn’t fertilised or animal has not become pregnant, the follicle will regress and the whole process begins again at day 21.So therefore prostaglandins (PGs) such as estrumate are only effective between day 5-17 generally and you will have up to 9-10 days of the cycle where giving them PGs has no effect on that cycle. This is where the strategic protocols have been developed to get heifers in heat using PGs. There are three options I apply on farms with heifers using PGs. Whichever one you use can be in relation to time and labour or cost. This should be done in consultation with your own vet.
Give the heifer two shots of PG 11 days apart and breed 48-72 hours after second injection at day 11 when showing signs of heat. I prefer to breed heifers that have been observed in heat as opposed to using fixed time AI with this protocol. However some people will use fixed time AI with this technique, but in my experience this yields lower conception rates.Give one shot of PG on day one and tail paint and breed any heifers seen in heat after first injection. Those not served after the first shot should be injected at day 11 again with a PG and breed on observed signs of heat 48-72hrs later. This is more labour intensive but less costly as you require less PG.Observe heat for seven days and AI heifers seen bulling in that period. At day seven, inject PG to heifers not seen bulling in first seven days and then breed them on signs of heat usually 48-72 hours later. This is less costly than the options outline above, but more labour intensive.By adopting these protocols, we allow more controlled breeding and even those heifers missed will be repeating at more regular intervals for the rest of the breeding season. Of course there are more sophisticated and expensive techniques; your own vet will help you manage these. The important message is if using prostaglandins, heifers must be cycling and they are only active when a functioning CL is present.
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