*Krissa Welshans holds a bachelor's degree in animal science from Michigan State University and a master's degree in public policy from New England College. Welshans has long been involved in agriculture and has worked with numerous agricultural groups, including the Animal Agriculture Alliance.
SUMMER is a challenging time for dairy cows because hotter temperatures make it difficult for dairy cows to regulate their body temperature.
South Dakota State University Extension dairy specialist Alvaro Garcia recently offered tips for keeping dairy cattle cool during the warm summer months.
"Body temperature regulation in dairy cows is constantly challenged by a combination of environmental heat and the heat produced during rumen fermentation and nutrient metabolism," Garcia said. "Heat stress occurs when cows cannot dissipate enough heat to maintain their core body temperature below 101.3 degrees F."
He added that air velocity also increases the maximum threshold, suggesting that cows housed in facilities with forced air can tolerate a higher ambient body temperature.
Many states have been experiencing a few days of high temperatures and then unusually cool days and nights. Because of the cooler spring overall, the rapid shift has the potential to produce stressful conditions for livestock. Garcia explained that this does not give cows the chance to acclimate.
"Cattle usually need two to four weeks of gradual temperature buildup to adapt to changes. Temperatures above the mid-80s can be very stressful, particularly if there is little air movement and humidity is above 50%," Garcia said.
When temperatures exceed 75 degrees F, feed intake drops considerably, even at 50% relative humidity.
Garcia said close-up and early-lactation cows are the most sensitive to heat stress and need more stringent cooling strategies. One strategy he suggested is soaking the cows with water.
"Heat loss through the skin can be improved when both skin and coat are soaked," Garcia said. "Cows can tolerate greater body temperature during the day when ambient body temperature during the night drops below 70 degrees F. Keep soaking them in the evening to help accomplish this."
He added that intake and production are more closely associated with the temperature of the two previous days than of the present one.
"Whenever necessary, it is important to have strategies that reduce temperature at night," Garcia advised.
In order for soaking to be effective, Garcia said sprinklers must soak the cows' coat and skin and should work intermittently to allow time for water to evaporate before the next soaking cycle.
"Fans alone are not enough. Treating cows under severe heat stress with sprinklers or fans alone is not enough. Both strategies need to be combined," he noted.
Garcia added that the effectiveness of the cooling system depends on the number of rows of cubicles: if there are four rows, then the sprinklers should be over the feed bunk and there should be two rows of fans — one over the cubicles and one over the feed bunk; if working with two rows, then there should be one row of sprinklers over the feed bunk and one row of fans over the cubicles.
He warned dairy producers about the risks associated with high-pressure misters, noting that they reduce the amount of water used but eject very small droplets, making it difficult to completely soak the animals' coat and skin.
"They create an air space between the skin and the water film, which insulates and impairs heat dissipation," he said. "To achieve cooling, they must work with a minimum water flow of 3.4 gal. per hour with five-minute cycles."
He explained that if the temperature is 86 degrees F, the soaking cycle frequency needs to be every eight minutes (one minute on/seven minutes off). When the cow's body temperature exceeds 68 degrees F, the fans should work continuously.
"Supplemental fan cooling, in combination with low-pressure feed bunk sprinklers, can reduce the effects of heat stress on milk production and intake," Garcia explained. "Providing clean and fresh water, enough shade and adequate air circulation is critical to maintain production. These systems should be accompanied by key nutritional management strategies suggested for hot weather."
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Water quality
A recently completed study of water supplies on Pennsylvania dairy farms found that about a quarter of those tested had at least one water quality issue, and average milk production for those farms was about 10% lower than farms with good water quality.
Dairy farms rely on good-quality water to ensure maximum milk production and herd health, according to study author Bryan Swistock, extension water resources specialist with The Pennsylvania State University College of Agricultural Sciences.
"While most dairy farms routinely test their water supplies for bacteria, additional testing for salts, metals and other parameters that can affect herd performance is conducted less frequently," Swistock said.
"In the fall of 2012, Penn State Extension offered free water testing for dairy farmers across Pennsylvania," he added. "The objective of the project was to increase awareness of various water quality parameters that are not tested as often. These less-tested parameters may explain chronic herd performance issues."
More than 240 dairy farmers who expressed an interest received water test kits, and 174 water samples from 41 counties were returned to the Penn State Agricultural Analytical Services Laboratory.
Ninety-eight percent of the water samples came from private wells or springs on the dairy farms. The farms in the study encompassed 51,000 acres and 18,000 cows with an average milk production level ranging from 20 to 90 lb. of milk per cow per day. Only six (3%) of the farms in the study had water meters to document their herds' water consumption.
"Overall, 45 of the water supplies, or 26%, had at least one water quality issue," Swistock said. "Average milk production for these 45 farms was 56 lb. per cow per day, compared to 62 lb. on the 129 farms with good water quality."
Swistock noted that none of the farms with high milk production (more than 75 lb. of milk per cow per day) had existing water quality problems, while 32% of farms with low milk production (less than 50 lb. of milk per cow) had at least one potential water quality problem.
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Pakistan dairy project
The U.S. Agency for International Development's Dairy Project has spurred growth in Pakistan's rural economy by helping female farmers increase their incomes and improve their livelihoods.
Realizing the pivotal role rural women play in Pakistan's livestock sector, USAID is creating a pool of up to 5,000 locally trained and readily available female livestock extension workers to provide rural dairy farmers with veterinary services and advice on cattle care and feeding. The project also provides the farmers with quality supplies for their animals, such as feed, vitamins and medication.
The dairy and livestock sectors contribute about 11% to the gross domestic product of Pakistan, and 45% of residents are employed in the agriculture sector. Most dairy farmers have only two to three cattle, and few have access to veterinary services that are crucial to improving milk yields.
The USAID Dairy Project, launched in July 2011, selects rural women with a high school diploma and trains them in basic animal health management techniques and entrepreneurship. The program has already trained 2,470 unemployed rural women, helping them earn an average of 2,500 rupees per month. It aims to train an additional 2,530 farmers.
"I am advising people in my village about how to improve milk production," said Asma, a resident of Punjab. "This USAID project has connected us with livestock experts and pharmaceutical companies we didn't know about before. So far, I have treated around 600 animals and earned 46,000 rupees."
Naazra, another beneficiary of the project, was trained as a livestock extension worker and is now successfully running her own business supplying concentrated feed to local dairy farmers.
"I have earned 30,000 rupees in three months by selling quality feed. I used the money to develop my business and meet the basic needs of my family," Naazra said.
Naazra and Asma represent change for rural livelihoods by helping to modernize Pakistan's dairy sector.
Volume:85 Issue:23