Monitoring Reproductive Programs Through Bovine Milk and Blood Progesterone

Is inaccurate heat detection making you see red on your bottomline?

Inaccurate heat detection is costly and often the weak link in a dairy’s breeding program. Research indicates that an average of 5 to 25% of cows are not in heat at the time of their insemination (Appleyard et al). Heat detection errors occur through poor heat detection technique or when a breeder is under unreasonable pressure to breed more cows. Some breeders will want to protect their conception rate by only breeding cows showing the strongest signs of estrus resulting in an insufficient number of cows bred and pregnancies created. The right balance of these two extremes will optimize pregnancy generation but how is this balance achieved? One answer may be to examine milk or serum progesterone levels at the time of breeding. Milk or serum samples are collected just after insemination and sent to a laboratory to estimate progesterone levels. Progesterone levels remain low for three days during estrus but should be at the lowest point at the time of insemination. If a cow is bred during her pre-estrus period, she will need to be re-bred on the day of actual estrus. If a cow is bred after standing estrus she may be okay as ovulation occurs after standing estrus.

Progesterone testing can also be used for monitoring synchronization protocol efficiency. Even with strong protocol compliance, synchronization program results will be disappointing if there are a significant number of non-cycling cows. Our research indicated that between 15% to 25% of cows are not cycling until 60 days post partum. In extreme cases, 20% to 25% of the cows were not cycling until about 75 days post partum.

Protocol for collecting milk/serum samples for heat detection accuracy:

a. Sample cows after technician breeds either by observed estrus or by secondary signs or by reading the chalk.

b. For examining efficacy of OvaSynch Program, sample a minimum of 20 animals on the day of breeding then re-sample the same animals 7-14 days post insemination.

c. Low progesterone at breeding and high progesterone 7-14 days post breeding indicates normal cycling of cows and validates the efficiency of the synchronization program.

d. Low progesterone at breeding and at 7-14 days post breeding may indicate a cow is non-cycling or undergoing early embryonic death

How to collect milk and serum samples:

1) Milk samples. As progesterone is a steroid hormone, it is five times more concentrated in milk fat than blood serum. After discarding ten to fifteen milk squirts on the ground (the first few squirts have a very small amount of milk fat), take a milk sample in a plastic bottle, about 2 ml, and add potassium dichromate tablet as a preservative. Correct sampling procedures are essential, otherwise errors in reading the progesterone could result. Label the bottle, and send it to the laboratory for assessing milk progesterone.

2) Blood samples. Blood samples. Blood progesterone is constant, but has less concentration as compared to milk. Obtain blood samples in red top tubes being careful not to break the vacuum in the tube. Once the samples have been collected, sit them upright in a warm place until the serum separates. Pour the serum off into an additional plastic tube. You can achieve the same results by centrifuging the serum.

Both milk and serum sampling methods will quantify the amount of progesterone in ng/ml. With improvements in technology, the costs for progesterone testing have come down in the last few years. Contact your Alta representative for more information.

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Posted Jun 26th

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