The DKC’s multidisciplinary team researches and brings management strategies that help dairy leaders to drive better business decisions.

The DKC’s  Management provides valuable knowledge in critical business areas such as nutrition and feeding, milking, reproduction, housing, and breeding practices.

Milking cows

Removing S. aureus from teat cup liners using automatic cluster flushing

Alvaro Garcia

Mastitis is an inflammation of the udder caused by microorganisms that enter the gland through the teat canal. Once inside the gland, these organisms find ideal conditions in which to multiply and, in turn damage the lining of the milk ducts, cistern, and alveoli. Contagious bacteria are spread from a cow with an infected udder to a healthy cow.

Transfer of pathogenic bacteria between cows usually occurs at milking time. Milker hands, towels, or the milking machine can all act as reservoirs for contagious bacteria. The major contagious pathogens are Streptococcus agalactiae, Staphylococcus aureus, and Mycoplasma spp.

The most important approach to minimize the transmission is to address potential sources of contagion at milking time. Cleaning the cluster between milkings has been used in commercial farms for quite some time. However, submerging the cluster in hot water (85°C) has been found not very effective in reducing the number of new intramammary infections.

Similarly, flushing has not achieved the complete eradication of new infections. Flushing with just cold water is frequently used in commercial farms since it is less costly, does not damage the equipment that much, and reduces the risk of residues in milk. Adding disinfectants to the water has also been explored as an alternative solution.

Using an iodine solution has been demonstrated to reduce intramammary infections by Corynebacterium bovis and coagulase-positive staphylococci. Given these results it seems that teat cleanliness, teat dipping, and an adequate milking routine are more effective in reducing the spread of infections than the attempts at washing or disinfecting the unit.

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Sprinklers

Cooling cows leads to hormone secretion that increases milk production

Álvaro García

Heat stress in lactating dairy cows leads to physiological responses that affect their well-being and performance. The peculiarity of their digestive system leads to increased heat increment, which further compounds with external environmental warm temperatures.

To cope with this heat overload, cows rely on two main mechanisms. One internal, which is to reduce feed intake and thus heat production, the second external which is to look for cooler spots in the barn or the field. The heat overload affects several aspects of the animal’s physiology, ranging from reductions in productivity, reproductive losses, all the may to increased incidence of digestive upsets.

Dairy farmers in warmer climates tackle this problem with a few different approaches targeting both internal and external sources of heat. One frequent approach (external) is to cool-off cow’s through water sprinklers, forced air through fans or a combination of both. Another approach (internal) is to increase the nutrient density of the diet to account for reduced feed intake. Despite all these efforts there is still always a sensible reduction in intake, which results in a negative energy balance.

A negative energy balance causes hormonal changes such as a reduction in leptin and an increment in ghrelin

This disparity between energy intake and its requirements for production leads to hormonal changes responsible for further drops in intake. One such change is the reduction in leptin and an increase in ghrelin. Leptin synthesized in the adipose tissue has important bearing in eating behavior, energy expenditure, and body weight. It signals the hypothalamus of the adequacy of the energy status in the body, and the need to reduce intake.

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Two cute Jersey calves

Which is the upper critical temperature-humidity index for dairy calves?

Alvaro Garcia

Thermostasis is the process by which warm-blooded animals keep their body temperature constant despite changes in environmental temperatures. Heat stress occurs when calves are incapable of dissipating enough heat to maintain their core body temperature below 38.5ºC. This increase in body temperature results from the combination of heat from the environment and that produced internally during nutrient metabolism.

In the northern hemisphere it is quite common for calves to be housed in polypropylene hutches with a small restricted outside area. During warm summer days calves seek the shade supplied by the hutch, however the heat inside of it will be concentrated. The calf then resorts to physiological mechanisms to lower its body temperature.

Under these conditions it is easy to verify an accelerated respiratory rate also accompanied by increases in rectal temperature, ear temperature, heart rate, and salivary cortisol (SC).

Ambient temperature and humidity determine the heat stress threshold

Not only is the absolute ambient temperature important but its combination with humidity in what is known as the temperature-humidity index (THI).

In adult cattle the upper critical value for this index is between 72 and 74, with some authors even considering up to 78 before respiratory rate and rectal temperature increase. In young calves however the optimum THI has not been determined, it is suspected however it should differ from a mature lactating cow since the heat increment resulting from forage fermentation in the rumen is very low, and the metabolic heat associated with milk production is non-existent.

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A little herd of cute Holstein calves on the grass

Trace minerals injection increases immunity in young dairy calves

Alvaro Garcia

Diarrhea and respiratory disease are the two leading death losses in un-weaned heifer calves. Respiratory problems have increased in the last 20 years, causing more than 20% percent of all dairy calf losses. Heifers that survive continue to perform poorly as adult cows.

Calf deaths within the first 48 hours of life are significant and greatly influenced by nutrition, environment, and management. One of the most prevalent reason for these death losses is the inadequate passive transfer of immunity through colostrum received from the dam. Current guidelines suggest calves should receive 3–4 quarts of high-quality colostrum within 1 hour of birth and 3 additional quarts within the next 12 hours.

If colostrum ingestion is inadequate, esophageal feeders can be used making sure that 3–4 quarts are administered within 1 hour of birth. Pooling colostrum is also becoming popular with large farms because it increases the immune competence of the calves (or their ability to respond to a more diverse pool of pathogens).

Have you fed your calf enough colostrum?

One way to find out if colostrum has supplied adequate amounts of immunoglobulins (IgG) is to measure either IgG directly or serum total protein in blood serum. Serum total protein measured with a refractometer is highly correlated with serum IgG levels. Measuring serum total protein in a group of calves is more meaningful than individual readings; at least 80% of a group of calves should have serum protein levels of 5.5 g/dL or higher.

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Green cereal field

Economic evaluation of double cropping winter annuals and corn

Alvaro Garcia

Maintaining acceptable profitability in an environmentally sustainable way are aims of most successful dairy farms. Economies of scale dictate that most farms add cows while either maintaining a similar land base or renting additional area. In order to accomplish this, it is imperative to maximize forage production from their current land base without increasing the environmental footprint.

Double cropping has been suggested as an alternative agricultural practice that reduces the environmental impact and increases forage yield per hectare. Small grain winter annuals, such as rye (Secale cereal L.), triticale (× Triticosecale), wheat (Triticum aestivum L.), and barley (Hordeum vulgare L.) can be double cropped with corn silage.

Increasing DM yields, and improving economic and environmental effects of the farm

Small grain winter annual cover crops are terminated before they reach maturity, double-cropped annuals on the other hand, are harvested as grain or preserved as silage. By doing this a double cropping system can increase the demands for nutrient cycling within the farm and reduce the inputs imported into the system. Double cropping can thus increase the profitability of the dairy enterprise by increasing yearly DM yields and improving the economic and environmental effects.

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Cute Holstein calf hidden in the grass

Lessening heat stress pre- and post-calving improves dairy calf performance

Alvaro Garcia

Thermostasis is the process by which animals attempt to keep body temperature constant despite changes in environmental temperatures. Heat stress occurs when cows are incapable of dissipating enough heat to maintain their core body temperature. This increase in body temperature results from the combination of heat from the environment and heat increment produced internally during rumen fermentation and nutrient metabolism. In addition, heat stress increases respiratory frequency (panting) to enhance heat dissipation.

Heat increment is greater at higher feed intakes and milk production, which is why high-producing cows are more sensitive to heat stress than their lower-producing counterparts. While there has been extensive research analyzing these effects in mature cows, comparatively little has been done addressing the potential negative consequences on future productivity, health, and reproduction, of their offspring.

Long-term consequences of suffering heat stress in utero and immediately after birth

Aside for shade, pre-weaned calves are not usually considered a priority when heat abatement strategies are implemented in the farm. The main reasons are that they have a larger surface/mass ratio, and not highly significant heat increment, smaller heat loads, when compared to mature cows. However, heat stress in heifer calves both in utero as well as immediately after birth, can have long-term consequences on their future productivity in the herd.

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A herd of croosbreed cows resting under the trees

Economics of dairy crossbreeding in conventional and organic herds

Alvaro Garcia

Crossbreeding remains an important production approach in several species of farm animals. The productive/economic advantages of crossbreeding have been known for a long time, and they include improved health, growth, fertility, and production.

Dairy cattle has not been the exception with crossbreeding showing improvements in fertility, health, calving ease, and longevity. There is no doubt these traits can provide economic advantages, particularly in times where returns to the dairy business are challenged.

In spite of these obvious advantages there are farmers that still prefer working with the more traditional pure-breed system. There are limited studies to date that have explored the effects of crossbreeding on animal performance and its impact on farm profitability. To consider this approach both parental breeds should have production traits that can be transferred to the offspring, and rival those of the original individual breeds. Swedish Holstein (SH) and Swedish Red (SR) are considered at a similar economic, and even complementary level, since SH provides higher income from milk yield, and SR have better health and other functional traits.

Advantages of using crossbreed cows

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Importance of timely euthanasia in dairy farming

Andrés Haro & Fernando Diaz

Farmers understand dairy cow well-being is critical to optimize their performance. When cows’ health is compromised by disease or trauma that deteriorates their well-being, and causes pain and suffering that cannot be alleviated by treatment, culling through timely euthanasia should be recommended

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Lying and eating behavior of Jersey and Holstein cows

Alvaro Garcia

Cow behavior has been the subject of much research in recent years with the intention to optimize their management and well-being. The development of automated devices that constantly monitor the cow’s activity has greatly helped form this perspective. Technologies that measure remotely cattle movements, temperature, rumination, and other physiological parameters have found their way from research facilities into commercial dairy farms.

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Dairy cow postpartum stimulation with equine chorionic gonadotropin

Andrés Haro & Alvaro Garcia

To achieve their greatest reproductive potential, dairy cows need to conceive as soon as possible after calving. Endocrine changes, referred to as the return to post-partum ovarian activity, occur after uterine involution and function normalization of the hypothalamus-hypophysis-ovarian axis. The use of equine chorionic gonadotropin (eCG) in lactating cows can induce post-partum ovarian activity causing follicle growth to resume.

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