Amber’s Top Ten Tips: Assessing Dairy Cow Behavior
Cow comfort” and “animal welfare” are two phrases receiving an increased amount of attention from dairy producers across the nation. Have you heard these phrases recently? Do you know what they mean? How do you measure cow comfort? As you consider these questions, let’s start at the beginning: animal behavior. I spent the last seven years working on animal behavior in lizards, horses, goats, and cattle. For the purpose of this article, I will focus on dairy cow behavior. I encourage you to attempt to identify the following ten cow behaviors on your dairy and consider how changes in some of these behaviors may help you identify issues in the herd:
Decreases in the amount of time a cow spends at the feed bunk may indicate metritis, ketosis, or, locomotion disorders.
Isolation behavior (or seclusion from the rest of the herd) may occur prior to calving.
Cows develop a social hierarchy within a herd. Cows ranked lower in social hierarchy are displaced at the feed bunk more often than cows ranked higher in the social hierarchy.
Restlessness, chin resting on other cows, standing heat, and increases in walking are all behavioral tools used to detect estrus in cows.
Following calving, cows lick their calves to stimulate calf activity and dry the calf’s coat. Cows may also display a flehmen response (elevation of head combined with retraction of the upper lip) towards the calf and amniotic fluids.
During the six hours prior to calving, cows will increase their number of lying bouts, but will decrease their overall time spent lying.
Water consumption increases during heat stress conditions, but cows will decrease their time spent drinking prior to calving.
One week prior to calving and during the day of calving, cows diagnosed with ketosis increase the amount of time they spend standing.
Stereotypic (repetitive behaviors that hove no obvious function)
Increases in number of tongue-rolling occurrences within a herd may be associated with restrictive feeding.
As feeding space at the bunk decreases, the number of aggressive displacements at the bunk increases.
Revisiting Subacute Ruminal Acidosis (SARA)
Subacute Ruminal Acidosis (SARA) is a consequence of our selection for high-producing dairy cattle. To reach their genetic potential for production, these animals need a nutrient dense, high energy diet. Their daily dry matter intake (DMI) is greater than previous average dairy cattle DMI levels. These highly-productive animals are therefore ingesting large quantities of fermentable carbohydrates, which can overwhelm the rumen’s ability to absorb volatile fatty acids (VFAs) and regulate acidity (pH).
Although the definition of SARA can vary, multiple researchers define it as a rumen pH below 5.5 for at least three hours a day. SARA is not rare; one study reported an incidence rate of 26% of mid-lactation and 19% of early lactation cows. It is most common between calving and 150 days of lactation, especially around 90 days as DMI increases with peak milk production. It significantly reduces milk production and components, either directly or indirectly increases culling rates, and can kill cows. Annual industry costs have previously been estimated at $500M to $1B.
Risk Factors for SARA
- Feeding high dietary levels of rapidly-fermentable carbohydrates (grains, molasses, etc.)
- Feeding ration by components vs. as a total mixed ration (TMR)
- Offering few large meals or irregular meals
- Poorly-mixed TMR
- Over-mixed TMR
- Lack of effective fiber in TMR
- Excessive fiber particle length, resulting in TMR sorting and grain overconsumption
- Lack of adequate bunk space so not all animals have access to all TMR components
- Lack of comfortable and sufficient stalls to encourage rumination
All cattle should be monitored closely for signs of SARA up until about day 150 of lactation, when decreasing feed intake reduces their risk. Signs of the condition are vague and subtle, but can include reduced milk production, reduced feed intake, weight loss, lack of cud chewing, milk fat depression, and/or foamy or otherwise abnormal diarrhea that may include intestinal tissue casts. However, some of the most important consequences of SARA may not occur for many weeks. Laminitis (founder) is a common occurrence, and rumenitis from SARA can seed the body with bacteria and result in sole abscesses, sole ulcers, liver abscesses, and even lung abscesses that erode into lung blood vessels and cause the cow to bleed to death.
Rumen pH can be measured in several animals in a group to determine the presence of SARA. Samples should be taken between 6 to 10 hours after the first TMR feeding of the day. Samples taken via stomach tube are often inaccurate, depending on where the sample was taken. A veterinarian can take an accurate sample directly from the rumen. If more than 25% of rumens sampled have a pH < 5.5, SARA is lurking in the group.
Ruminant saliva contains natural buffers, including bicarbonate. A diet containing sufficient effective fiber stimulates rumination, which increases saliva production and self-buffering of rumen pH. Another self-regulating mechanism is feed intake: as rumen pH decreases and the concentration of osmotically-active particles in the rumen increases, appetite is suppressed—this prevents additional intake of highly-fermentable fiber and gives the rumen time to re-balance pH.
Populations of rumen microbes are highly variable and are determined by pH, feed substrates available, and other factors. Microbes need time to adapt from high fiber dry cow rations to high concentrate lactating rations. A lead time of 3 to 5 weeks is needed to prepare rumens for lactating diets. This will ensure the right microbes are present to digest feeds and regulate the rate of production and consumption of rumen acids (VFAs and lactic acid). Grain feeding results in the production of butyric and propionic VFAs, which stimulates lengthening of rumen papillae. Long and healthy papillae are able to absorb VFAs quickly and moderate rumen pH (photo 1).
Effects of Rumenitis
If the rumen lining is repeatedly exposed to low pH levels (<5.5), it can become inflamed, eroded, ulcerated, scarred, and hyperpigmented; rumen papillae are stunted and lost. The result is reduced absorption of VFAs from the rumen, which further drops pH. This condition is probably painful and reduces feed intake as well. Rumen inflammation causes production of certain proteins and other markers characteristic of inflammatory processes, and their presence is sometimes used to diagnose SARA
Importance of Regular Meals
Irregular feeding schedules, lack of adequate bunk space, prolonged pre-milking or vet check holding times, and other factors that keep cows away from feed can set the stage for SARA. Here’s why: without the continued intake of a high-concentrate ration, rumen pH rises. This can kill certain types of rumen bacteria, particularly those that use lactic acid and help keep pH from falling too low. With less of these bacteria available, the animal is less able to moderate rumen pH when it takes in feed again. Animals that have not had access to the feed bunk for a while often eat an unusually large meal when feed is made available, which also contributes to falling rumen pH.
Low rumen pH decreases the variety of rumen microbes, causing a less stable rumen pH and reducing the animal’s capacity to regulate pH. Below a pH of 5.5, lactate-producing bacteria proliferate and reduce pH even more.
Causes of SARA
- Insufficient rumen buffering (inadequate effective fiber, DCAD, and/or natural buffers)
- Excessive highly-fermentable carbohydrates in diet
- Lack of rumen’s adaptation to a high-concentrate diet
Reducing the Risk of SARA
High roughage/low concentrate rations can eliminate SARA, but they won’t support maximum milk production. Rations should be fine-tuned and not supply more highly-fermentable carbohydrates than needed; contain adequate effective fiber; include buffers such as sodium bicarbonate and the recommended dietary anion-cation difference (DCAD); be re-formulated as needed to adjust for changing dry matter content of different batches of feedstuffs; and possibly include probiotics including yeast and bacteria that use lactic acid.
Corn silage is a known risk factor for SARA. It has variable digestibility and moisture and insufficient long fiber to promote rumination and buffering. It may need to be mixed with additional fiber in the form of dry hay to meet recommended effective fiber and dry matter content in the TMR.
Bunk management is critical to minimizing SARA. Ensure adequate space so all animals have access to the complete TMR, not the dregs that remain from sorting. Check the TMR throughout the day to monitor the degree of sorting that occurs and correct chopping or mixing as needed. Check to be sure the ration formulated on paper is the ration delivered to and eaten by cows. Keep feed in bunks—if bunks are empty, cows that want to eat will have nothing and their rumen pH will not be stable; SARA can ensue.
- Plaizier, J.C., D.O. Krause, G.N. Gozho, & B.W. McBride. 2008. Subacute ruminal acidosis in dairy cows: The physiological causes, incidence and consequences. The Veterinary Journal, 176(1), 21–31. doi:10.1016/j.tvjl.2007.12.016
- Krause, K.M., & G.R. Oetzel. 2006. Understanding and preventing subacute ruminal acidosis in dairy herds: A review. Animal Feed Science and Technology, 126(3–4), 215–236. doi:10.1016/j.anifeedsci.2005.08.004
- Enemark, J.M.D. The monitoring, prevention and treatment of sub-acute ruminal acidosis (SARA): A review. 2008. The Veterinary Journal, 176(1), 32–43. doi:10.1016/j.tvjl.2007.12.021
Winter Kill on Grass Fields in Western Washington
Did you notice winter kill on grass fields over the later 2014 – early 2015 time period? If so, the answer may be related to lack of dormancy going into winter period.
Nutrient management is important all times of the year in forage production systems. However, the fall (September) period is the beginning of the annual calendar cycle of adapted grasses, including ryegrass. The grass plant will generate new roots and new growing points in the fall period only to shed those roots during the winter. If grasses are not allowed to transition into a dormancy state in the late fall, such as late October to mid-November, and grass growth remains active then the probability of winterkill increases.
Nutrients such as N in early fall may contribute to continued active fall growth, delaying fall dormancy. So, if we start with a low stubble harvest height in the final cutting, compound the plant mechanism of lower grass sugars and active grass growth from higher soil N availability, then add one below normal, very cold Arctic blast, we have the perfect storm for winterkill. This happened to many grass producers in 1988 resulting in thousands of westside acres of perennial grasses dead. This perfect storm was repeated in the fall and early winter of 2014. As our crops are emerging from winter dormancy and into spring greenup, the results of that perfect storm are clear.
Perennial and annual ryegrasses store the highest amount of sugars in the stem and basal (crown) tissue of any cool-season grasses grown in the PNW. We expect the range of these fructosan sugars to range above 20% to nearly 30%. Fructosan sugars can be thought of as the anti-freeze in these highly productive and high quality westside grasses. Even though the sugar may differ among grass crops, the net result is similar, increased winterhardiness and rapid regrowth after harvesting. Unlike alfalfa and other legumes where the sugar (starch in this case) is stored in the crown and tap root, cool-season grasses store sugars in the basal 3 to 4 inches of the stubble.
Grazing or cutting with machines to close to the ground will remove essential sugars for growth and survival. This is not just in the final fall harvest but all cuttings over the growing season. What sets up the critical fall grass establishment period is the summer. Measure sugar concentrations in the summer and you’ll find them lower than at any time of the growing season. In the fall, sugar levels should be at their highest, not lowest. Another important characteristic in grass management is the inverse interrelationship between nitrogen (Crude Protein) and sugar concentrations. As CP increases sugar concentrations decrease. Decreasing stored sugars reduce winterhardiness in tame cool-season grasses, such as ryegrass. Nutrient management is important all times of the year in forage production systems.
Thus, we never recommend either harvesting or grazing cool-season grasses less than three-inches. For timothy and a couple other grasses, never less than four inches. Thus, lower summer cutting heights reduce sugars proceeding into September, not a prime situation when the plants essentially establish productive potential at this time for the following year. Secondly, to increase September and fall sugar storage in the stubble and in the above ground growth, the plants must conserve sugars to transition into a state of winter dormancy.
On the westside this dormancy level does not need to be as severe or deep as Minnesota and the upper mid-west for winter survival, but westside grass winter dormancy is important. Third, nutrient applications of manure or fertilizer N may prolong fall growth, reduce sugar concentrations and inhibit winter dormancy. Timing of transition is dependent upon fall temperatures, soil temperatures, fall rains, soil moisture status, grass genetics and health of the plant.
Fall is not a time when producers can slack off on their grass management, actually the opposite is true. Fall is when you need to do the best possible job to reduce winterkill injury and enhance rapid, early spring growth.
Finally, as grasses emerge in the spring, they are often lower in sugars than when they entered winter dormancy. Avoid early turnout on to pastures until atl east six to eight inches of growth have been attained. Reduction of stands can occur in summer, when grasses are shedding roots when plants do not have enough sugars for high respiration rates in summer heat then placing the plant in a less than productive state entering the critical fall period.Steve Fransen, Forage Agronomist, firstname.lastname@example.org
Joe Harrison, Livestock Nutrient Management Specialist, email@example.com