Pregnancy Rate


As premature as this subject may seem in January, it has been well determined that the two drivers of farm profitability are; feed and pregnancy rate. The percentage of fresh cows in your herd each year will largely determine your milk production, assuming they have the feed to express their genetic potential and post-calving disposition to milk production.

The feed scenario we address in July/August for our clients in the form of a Feed Budget, carefully designed in consultation with the client, and based on the previous twelve months feed/production data. This article is focused on the pregnancy side of this dual profit driver. Once cows have calved, passed through the immediate post-calving phase and hopefully back in-calf, our focus then shifts to next lactation, without compromising the current one.

As distant as next joining maybe for many farms, our success with pregnancy rates, and viability, begins once our cow is confirmed pregnant this lactation. Planning now, as to how we are going to execute a breeding program, will include decisions regarding heat detection, choice of timed AI or natural presentation, nutrition, both pre and post calving and prevention/management of metabolic disorders at calving. A well-documented plan can contribute very significantly to a successful joining. In fact, these issues are quoted as contributing up to 96% of conception variations.

Obviously, our cow needs to dry-off in calving BCS. This means, no weight gain or loss during the dry phase. Recent research opinion has stated shorter dry periods (30 to 40 days) do produce earlier first heats and improved fertility. Long dry spells (greater than 100 days) are associated with poorer fertility. From personal experience, you must be very confident of calving dates to optimise shorter dry periods.

Much has been written, by me and many others, on transition nutrition. Best practice in this area has not changed a great deal for many years, verifying its validity. Maximising dry matter intake of a well-balanced diet fortified with sound mineral balance, calcium especially, and managed for Dietary Cation Anion Difference (DCAD). In regard to fertility, we have seen dramatically improved conception rates under controlled calcium nutrition through both the dry period and transition.

Sound nutrition and environmental conditions at calving can minimise uterine infection and dystocia which research has identified as possibly causing 60% of lost pregnancies in the first 60 days of gestation. High Rumen Degradable Protein (RDP) diets are also a cause of early fetal death.

Post-calving metabolic disorders certainly influence fertility and pregnancy rate. Milk fever/ketosis, but far more importantly, sub-clinical milk fever/ketosis, will hand string milk production dramatically, let alone conception. We have for a number of years drenched every cow at calving with propylene glycol, and our testing of milk with ketos test strips has validated this procedure as very effective.

I am impressed with controlled breeding through timed AI programs. It leaves little to chance and human observation as guidance to breeding, and coupled with 42 day post-insemination pregnancy testing are a powerful tool to manage pregnancy rate. Postnatal vet checks to ensure cows are clean and cycling we’ve done since the 1980’s.

If farmer insemination is part of either timed AI or natural presentation, much can be said for refresher courses on technique and semen handling. A client of ours attended a fertility course in the USA and was shocked by ‘marginal’ variations from protocols having significant effect on conception.

Many farms now use software to manage farm data, but especially breeding details. Most programs are capable of extracting performance data on breeding. This information is essential for review of procedures when less-than-optimum results occur.

Mastitis between calving and joining is well researched as a cause of conception failure. Mastitis between insemination and 42 days post-insemination has a very high mortality rate on early term pregnancies. Transition nutrition and calving environment play major roles, combined with dry cow therapy and teat seal in minimising post-calving mastitis incidence. Milking machine maintenance has also revealed on several farms its impact in mastitis control.

Good fertility breeds good fertility, and many other profit benefits. The client with the highest fertility, averaging around 60% conception on one insemination, soon had abundant replacement heifers. Over the last couple of years of high beef prices, and abundant young stock, he has culled ruthlessly, any repeat breeders, repeat mastitis, repeat lameness, and done quite nicely in his beef (culling) marketing enterprise. As one of my sons says; we are beef farmers who milk cows to pay the bills. Our profit is determined by a cow’s exit value!

A recent article from the USA on a dairy enterprise that has adopted a program of using sexed semen on all heifers, due to greatly improved conception rates, and beef semen on all third, fourth and greater lactation cows. They market the beef cross calves to a lucrative, high demand, grower market.

At my age, “To Do Lists” are as much a part of my life as eating and breathing. Failure of the to-do-list has about the same effect as not eating or breathing. The fertility issue is equally important to your farm’s viability and a well thought through and written plan can make a world of difference. We will address many of these issues in more detail in future articles. The other half of the profit matrix, feed, we’ll also address in regard to Feed Budgets in July/August.

John Lyne is a dairy production specialist with Dairytech Nutrition

John Lyne

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