Prolactin a protein levels are stimulated when the udder is suckled by the calf or milked by the milking machine and this needs to occur for milk production to continue. Cows are usually dried off, or milking is stopped, about two months before their next expected calving to allow the udder time to rest and reset itself for the following lactation. Dairy cows are selectively bred to produce high levels of milk and this is far more than a calf could normally drink.
The volume of milk produced by a cow will depend upon various factors, such as her level of nutrition, breed, genetics and age. For her to continue to produce milk once she has calved, she needs to be milked each day. Dairy Matters. You ask, we answer. Region of the country and soil type may affect how long the teeth remain sound and allow the cow to consume roughages such as pasture and hay.
Records kept by a very large ranch in Florida in the 's and published in the 33rd Annual Proceedings of the Beef Cattle Short Course by the University of Florida Animal Science Department show how productivity changes over the life of the beef cows. These large data sets, cows, and cows in two separate years were plotted to indicate the average percentage of cow determined to be pregnant based on their age in years. The data would indicate that cows are consistent in the rebreeding performance through about 8 years of age.
A small decline was noted in as cows aged from 8 to 10 years of age. However the most consistent decline in reproductive performance was noted after cows were 10 years of age.
This data, collected in Florida on cows with some Brahman influence, represents one of, if not the largest data set on this subject. Subscribe Marketing Packages Cookie Law. Follow thecattlesite. The culprit is isocupressic acid, a yellow, oily substance in pine needles. Identification of the culprit is the first step in developing an antidote. As far as I am aware, the antidote is not yet available. Answer from Modified-live virus MLV vaccines should be given when the cow is not pregnant — ideally days prior to breeding.
Some BVDV MLV products state on the label that they can be safely administered to pregnant cattle if the cattle had also received the vaccine prior to breeding. Although some cattle producers prefer to vaccinate during fall work for convenience; it makes the most sense from a BVDV control standpoint to vaccinate prior to breeding so that cattle have the best protection during early pregnancy.
Not an easy task to accomplish. Usually the length of the post-partum interval PPI, time from calving to the first estrous cycle is 45 to 55 days in beef cows. If cows are in good body condition at calving, then the PPI would be in the 45 to 50 day range and if in poor condition, the PPI would be longer. First-calf heifers have a longer PPI compared to mature cows, about 10 days longer if she has no calving difficulty and is in good body condition. If cows are exposed to bulls bull exposure after calving, then the PPI is usually shorter by may be as much as 10 days shorter.
It has been documented in beef cows that uterine involution is not completed by 20 days post-calving, but the uterus is back to its non-pregnant size by 30 days post-calving.
Another 10 or so days is needed to complete uterine involution and be prepared for another pregnancy. I don't think many cows will come into heat estrus before 35 day post calving. You can "jump start" estrous cycles with progestins and gonadotropins GnRH , but this will only happen in females that are close to begin cycling.
Use of these programs has the potential to induce estrous cycles in cows that are close to cycling. So, nutrition is very important, have cows in at least body condition score 5 at calving and don't skimp on the groceries after calving. Ionophores such as Rumensin or Bovetec have a positive impact on the reproductive axis, at least there are experiments using the heifer that demonstrate this, so consider using an ionophore in the ration after calving.
Expose cows to sterile bulls as soon after calving as possible. These considerations are all for not if the cows have not been managed properly from a nutritional perspective. Open cows are usually due to mis-management of the nutrition program. Minerals are important, but I rarely see large reductions in reproductive performance due to minerals alone, especially in Nebraska. A review of these studies conducted over the last several decades along with new research indicates the association among BW, puberty and heifer pregnancy rate appears to be changing over time.
In general, research reports published through the late s have shown much greater negative effects of limited post weaning growth on age of puberty and subsequent pregnancy, whereas more recent studies indicate less of a negative impact of delayed puberty on pregnancy response.
Several factors likely contribute to this change over time. Initial research in this area of interest corresponds to the industry shift from calving heifers at 3 years of age to calving at 2 years of age. Thus, selection pressure for age of puberty was probably minimal in the animals used in the early studies. While selection intensity would have increased with the reduction in calving age of heifers, genetic progress would take time due to the long generation interval in cattle.
In the mid s, researchers identified the association between scrotal circumference in bulls and age of puberty in their female offspring. Since then, scrotal circumference has been used as an indicator trait for puberty. The change occurring in scrotal circumference from to the present indicates substantial progress has been made, and a similar response in age of puberty would be expected see breed association websites for changes over time in EPD for scrotal circumference.
Indeed, the inability of heifers to attain puberty prior to breeding may not be as problematic as heifers reaching puberty before weaning. There are data developed at the University of Nebraska were feeding replacement heifers to a traditional target weight increases development costs relative to more extensive heifer development. We have recorded no negative effect on reproduction when beef cows are supplemented with distillers grains as a protein or energy source, or for both protein and energy.
In a number of experiments, we have used a distillers grains based cube as a major component of the supplement that is fed to cows prepartum while grazing cornstalks or dormant native range. Following reports provide examples of research where distiller was a part of the supplement and we recorded the impact on cow and calf performance.
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