Timothy and Alfalfa Hay Blog

Heat Stress Decreases Dairy Cow Milk Production

While it is currently winter in the northern hemisphere, dairy cows in some other parts of the world are experiencing environmental conditions that include high ambient temperature and relative humidity. Dairy farmers know that their cows are sensitive to heat stress on hot summer days. When the climate is subtropical, or when temperatures are hot and humid for extended periods of time, dairy cows may become chronically heat stressed.

The strain caused by chronic heat stress in lactating dairy cows can be detrimental to milk production.  Dairy producers in the United States lose more than $5 billion each year from heat stressed dairy cows that have depressed milk production and decreased performance (1).

Growth performance of young dairy calves can be improved if a source of chopped hay is included in their diets. Unfortunately, because of conflicting results from different research studies, the jury is still out as far as solid recommendations about when forage should be introduced in the young dairy calf diet and how much they should be fed.

Nutrient-Customized Timothy Hay to Reduce Hypocalcemia in Dairy Cows

Parturient paresis, or milk fever, is a disorder that most commonly affects dairy cattle around the time of calving. It is a metabolic disease caused by low blood calcium, or hypocalcemia. Symptoms of milk fever vary with severity of hypocalcemia, which can be separated into three progressive stages (1). In stage 1, animals are able to move about, but may show signs of incoordination. Cows in stage 2 cannot stand, but are able to sit up on their briskets (sternal recumbency). As hypocalcemia progresses to stage 3, cows lose consciousness and will only survive a few hours if not treated.

Why do cows get milk fever after calving? The demand for calcium increases precipitously with the onset of lactation. Loss of blood calcium to milk may exceed 50 grams each day, which is significantly greater than the 30 grams of calcium required before calving (2). The increased demand for calcium can only be met by increasing dietary calcium absorption or by mobilizing calcium from bones.

Feeding Higher Forage Diets before Calving Improves Dairy Cow Metabolic Health

Dairy cows are frequently afflicted with metabolic diseases after calving. The high incidence of disease is thought to be related to the prolonged periods of negative energy balance that commonly occur postpartum. The dietary energy requirements of dairy cows are at their highest levels at calving and immediately postpartum and in most cases, a cow cannot physically eat enough feed to meet her energy needs. For an unknown reason, this period is also characterized by a drop in dry matter intake. Therefore, during this time, the cow is in a state of negative energy balance (NEB).

In an effort to reduce NEB, many dairy producers will feed cows an energy dense diet beginning three weeks before calving. However, this practice may lead to overconsumption of energy, which is subsequently stored as triglycerides (fat stores) in adipose tissue. During times of NEB, triglycerides are broken down into non-esterified fatty acids (NEFA) that are used for energy. NEFA are transported in the blood to the liver where they are transformed into ketone bodies. Beta hydroxybutyrate (BHB) is the most common ketone body in dairy cows. While BHB is a highly available energy source, excess levels can lead to subclinical or clinical ketosis. Subclinical ketosis can decrease milk production and affect reproductive performance. In addition, surplus NEFA are repackaged into triglycerides in the liver, which accumulate, and thus, increase the risk of fatty liver. Metritis, retained fetal membranes, mastitis, milk fever, and displaced abomasum have been associated with fatty liver syndrome in dairy cows. Interestingly enough, cows that consume excess energy and are over-conditioned prior to calving tend to experience more extreme NEB postpartum and have higher concentrations of BHB than cows that were fed prepartum diets that met energy requirements.

High-producing dairy cows must be fed an energy-dense diet in order to meet requirements for milk production.  An energy-dense diet typically contains easily fermented carbohydrates (starches and sugars).  This type of diet must also contain a suitable level of roughage to uphold rumen health and functionality, allow adequate dry matter intake, sustain milk production and milk composition, and decrease susceptibility to metabolic disorders such as sub-acute ruminal acidosis (SARA). The metabolic disorder SARA typically affects cows in early to mid-lactation that are consuming highly-fermentable diets.  Consumption of large quantities of this type of diet causes ruminal pH to drop, which subsequently suppresses fiber digestion and leads to lower butterfat production.  In addition, low ruminal pH can lead to inflammation of rumen epithelium (tissue that lines the rumen) and ulceration. Cows with SARA may have diarrhea and sore hooves (laminitis). In advanced cases of SARA, bacteria grow on the inflamed ruminal papillae and eventually leak into blood vessels that flow into the liver, which results in liver abscesses (1).  

Livestock raised for milk production are representative of what they eat in terms of physical health, but also in terms of the quality of the milk they produce.  If you're in the dairy business, you know maintaining quality and quantity of milk production is key to maintaining profitability in today's volatile markets. Your top concern should be the quality of feed you're using to catalyze milk production in your livestock.  If your herd does not have access to feed that has been harvested at the right time, if forage is grown in poorly maintained soil conditions, or if it is allowed to collect dust, mold spores, and other pollutants during storage and transport, your herd, and milk supply, will suffer.

Quality of Forage: The nutritional content of Timothy Hay, Alfalfa Hay, and other grasses is highest when it is in its vegetative state.  At this point in its growth cycle, the leaves contain the majority of the energy and protein that dairy cattle need for optimal digestion.  If the hay is harvested later in the growth cycle the nutritional value, i.e. protein, phosphorous, energy, calcium and digestible dry matter begin to decrease and the stems and leaves become fibrous and more difficult for the cattle to digest.  This will result in lower milk production and lower fat content in the milk produced.  

The nutritional content of Timothy Hay has been shown to be beneficial for dry cows and cows that are close to calving to prevent low-grade milk fevers for which the cows may be asymptomatic. Studies show that feeding dairy cattle low-DCAD (dietary cation-anion difference) forage, such as Timothy Hay can be the best way to proactively prevent these conditions.

Soil Quality:  Plants derive their nutrients from the soil they're grown in. If your feed distributor does not have rigid quality control, you may be feeding your livestock nutrient depleted and pesticide rich forage, which is disastrous to healthy milk production.  Beneficial nutritional content of Timothy Hay requires soil that is rich in Nitrogen, and should also have healthy levels of Phosphorous and Nitrate.  You want to choose a distributor whose quality control maintains accurate traceability, with records demonstrating the soil quality prior to seeding.  Drought-stress can also play a role in the nutritional content of Timothy Hay as it creates a lower NDF (neutral detergent fiber) which can raise the protein content. However, long term drought is detrimental to the nutrient value, which is why quality control of harvest management is important.

Storage and Transport:  Once the forage has been harvested, it must be properly dried, stored, and transported to maintain its quality.  While dairy cattle are less susceptible to dust in their feed than horses are, it is still ideal to keep dust residues to a minimum.  Excessive dust can put your cattle at risk for dust pneumonia.  Attention also needs to be paid to the way the grass is stored while it is curing.  If it is not dried properly, mold spores are granted a desirable dark moist climate in which to grow.  Mold is responsible for mycosis and mycotoxicosis in cows which negatively affects the health of the herd and the herd's milk production. Chronic mycotoxicity will result in permanently low milk production and an unhealthy dependence on antibiotics.

As a responsible dairy farmer, or breeder, it's imperative you select a feed distributor that has a long standing and respected reputation and whose quality control maintains standards that exceed the normal industry protocols, like Anderson Hay.