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Newsletter of Penn Dutch Cow Care November 2004

Hi Folks,

As we are in the autumn months now, fertility is usually returning after the summer months. Although we had a pretty "easy" summer as far as no long stretches of heat spells, many cows still seem to rebounding. This means that when I am doing repro exams I often find a fair amount of animals within herds that exhibit good uterine "tone" - meaning the uterus is very well defined and has contractility. This usually means that a cow is near heat or in heat. This is great if you haven' t seen the cow in heat for a while but it is not good if you thought she was already bred.

Knowing that a cow is near heat is obviously important for those of you doing artificial insemination so you know when to breed her. Traditionally, it was thought that you should wait to perform artificial insemination (AI) for 12 hours after you see the cow in heat. This was based partially on the biology of the cow since it is known that the egg is released from the dominant follicle after the cow shows heat. The research that really propelled the idea of the AM-PM breeding routine was done in the 1940' s with cows being observed three times daily for signs of heat; once heat was observed, the cow was checked every two hours for further activity, then insemination times were recorded and success rates were evaluated and compared.

The onset of heat (estrus) is very important because the egg will be released at some point afterward. The egg is freshest at the time of release from the follicle and ages over the hours. If watching for heat 6 times a day, the onset of heat can be detected with fairly good accuracy. But most farmers don't watch this often - they watch maybe twice a day. If this is the case (which it usually is), then the farmer really doesn' t know when the onset of heat/estrus takes place and breeding should be done sooner than later to take advantage of the freshest timing for the egg. In other words, when you see a cow in heat, you should breed her within 12 hours, preferably 6-8 hours. Think about it, if you happen to see the cow during her very last standing heat behavior and then wait 12 hours, you could easily be too late and not get the best timing for the egg being released. Another way to think about it is -would a bull wait 12 hours?? Of course not, so maybe we should observe nature more and follow it a bit more closely instead of simply being "traditional" . But hey, if your AI breeding is going just fine, don' t change anything. But if you feel that you are having too many cows returning to heat, perhaps breeding them sooner would be worth considering.

There certainly can be other reasons for cows returning to heat when they have been bred previously other than poor AI timing. For instance, in bull bred herds, if there are may repeats, either the bull is not fertile enough, there are too many cows per bull, the cows and bull are passing an infection back and forth and/or perhaps there is a nutritional deficiency. There should be no more than about 25 cows per bull if you are trying to get cows bred in a tight window of time (as in a strong spring flush or in totally seasonal situations). It is fairly easy to tell if an infection is the reason, as there will be discharge seen on the cows' tails or upon reproductive examination there will be evidence of a slight increase in the size of a few cow' s uterine horns. A slightly increased uterine horn size may also indicate a pregnancy which is now being resorbed (early embryonic death). Bull breeding soundness exams can be conducted but need some specialized equipment to collect and analyze fresh semen at the farm. Ideally, that should be done before the breeding season starts rather than after a few miserable herd checks.

Nutritional deficiencies probably revolve more around micro-nutrient minerals than protein or energy, although poor energy intake will definitely hinder conception. Poor energy intake is usually obvious by seeing skinny cows for months on end. This may be seen on grazing farms when not enough effective fiber is being fed and the fresh grass is exiting the digestive tract too quickly and cows have too loose manure (diarrhea) for too long. Keep in mind that if skinny cows are observed, there will likely be micro-nutrient deficiencies as well. This is because the animals are depleting their mineral stores from their bones (the skeleton is the major bank of minerals in the body). An obvious symptom of mineral imbalance is when animals are seen licking the soil, stones, concrete or walls in attempts to regain minerals not available in their normal feed.

Some of the important micro-minerals include selenium, zinc, copper, manganese and cobalt. Selenium deficiency is classically seen in newborn calves having white muscle disease, however, it is more often seen as retained placentas without there being a problem calving (i.e. no twins, not early, not a hard calving). Selenium also helps the immune system and can help if high somatic cell counts are a problem. Zinc deficiency may show reduced conception rates, increased retained placentas, hoof problems (strawberry heel, laminitis, heel cracks), low quality milk due to high somatic cell count, and slow wound healing. Copper deficiency may show reduced conception although heats are being seen, early embryonic death (although BVD can certainly cause early embryonic death as well), possible increase in retained placenta and diarrhea. Manganese deficiency may be seen as no heats or silent heats, reduced conception rate, slow or delayed ovulation and increased abortion (although BVD, lepto and neospora may also cause abortions).Cobalt deficiency, which is required for production of vitamin B12, may result in reduced fertility but is more associated with increased early calf mortality. All of these micro-nutrients can cause an animal, especially a younger one, to have a poor hair coat and poor growth of the skeleton, legs and joints (but parasitism can also cause symptoms of animals looking rough and not thriving). Chronically loose manure (diarrhea) will certainly deplete the animal' s system of minerals as well as protein and in adults we should think of Johnes disease or inadequate dry hay being fed. Either way, minerals are being wasted away.

Obviously, your nutritionist will be able to advise you on the proper levels of the micro-nutrients to be feeding based on what is being provided by your forages. Please keep in mind that most minerals are absorbed better through the digestive tract than by syringe and needle. Generally speaking, if your animals in your herd look sleek, have shiny hair coats, and are in proper body condition for their stage of lactation, they will most likely be able to get bred back in the time period that you would like. In short, doing your part in watching for heats, breeding them in time, feeding them well and doing regularly scheduled reproductive examinations will enable you to have cows freshen when you would like them to.

John K. Lapp has 6 + certified organic Holstein young stock for sale, take your pick of age. His address is 95 Indiantown Rd., Ephrata 17522 and phone is 717-733-1766

 

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