Milk Fever and Low Blood Calcium in Dairy Cows. Part IBy Pedro Nogueira

Inside this Issue...

Milk Fever and Low Blood Calcium in Dairy Cows. Part I

By: Pedro NogueiraCows, Stress and Nutrition

By: Pedro Nogueira

69819 London Road, RR #1, Centralia, Ontario, Canada, N0M 1K0 Tel: (519) 228-6444 or 1-800-265-2904 • Fax (519) 228-6560 • Email kpalen@kenpal.on.ca • www.kenpal.on.ca

Volume 3, Issue 1February, 2010

con’t >>

The Latest Information on Dairy Cattle Nutrition

Dairy farming is not one of the most predictable types of production. Sometimes producing milk is “like a pic-nik” like I heard sometime ago a producer say, but other times, even on well managed operations, dairy cows experience several types of problems, especially around the transition period. In fact, most of the metabolic diseases of dairy cows - milk fever, ketosis, retained placenta, and displacement of the abomasum - occur within the first 2 weeks of lactation. When these type of problems become serious it can turn dairy farming into a very stressful and frustrating activity. Sometimes we almost wish that cows would not have to calve, but so far, efficient milk production continues to require that the dairy cow goes through a gestation and calving each year. In this article we’ll discuss what hypocalcaemia is and why it is implicated in so many other problems. In the next article we’ll focus on prevention measures through diet and mineral nutrition.

Of the different metabolic diseases experienced by dairy cows, milk fever and sub-clinical hypocalcaemia are the most important macro-mineral disorders that affect transition dairy cows. The aspect that makes this disease especially problematic is that milk fever is related to the occurrence of many other problems, the timing of which would suggest that milk fever was at least one (if not the only) predisposing factor that lead to a second transition or early-lactation cow disorder.

When the cows actually “go down” with hypocalcaemia this is a consequence of severe low levels of calcium in blood. Because calcium is necessary for nerve and muscle function, the cow loses the ability to rise to her feet.

Clinical hypocalcaemia is very noticeable and has relatively clear symptoms. As it shows such noticeable symptoms, the problem is readily recognized and the cow is treated, normally recovering well, although still being very negative to the cow. Ironically, sometimes the problems can be more pronounced when

increased milk production• maintains or improves • butterfatcows peak higher and • fasterimproved feed efficiency• decreased loss of body • weight in early lactationmaintains energy intake • during hot weatherreduces separation in • mixed feeds and TMR rations

FORDAIRY

Lacta-Fat may provide many nutritional benefits to dairy cattle including:

Call your Kenpal Salesmantoday for more information

con’t >>February 2010 • Kenpal Dairy Brief • 2

the cow doesn’t “go down” but has nevertheless lower than normal blood calcium levels, or sub-clinical hypocalcaemia. According to Dr. Mike Hutjens, milk fever affects 3 to 6 percent of the dairy cows in the US and a growing body of research indicates that up to 60 percent or more of dairy cows in high producing herds can experience sub clinical hypocalcaemia. This high level of hypocalcaemia can occur in herds that experience few clinical cases of milk fever. Sub clinical hypocalcaemia are cows with low blood calcium (<8 mg/dl), but not low enough to cause the cow to go down with clinical milk fever (< 5.0 mg /dl). In a national US survey conducted in 2002 on over 1400 dairy cows, researchers determined that 25, 42 and 53 percent of 1st, 2nd and 3rd lactation and over cows, respectively, had blood calcium levels of below 8 mg/dl.

Dr. Jesse P. Goff from the US National Animal Disease Center indicates that less severe disturbances in blood Ca concentration can impact different systems. It’s a chain reaction that can be a disaster. He says that milk fever and sub clinical milk fever should be considered gateway diseases that greatly reduce the chance for full productivity in the ensuing lactation. Hypocalcaemia reduces rumen and abomasal motility increasing the risk of abomasal displacement. Reduces feed intake so that greater body fat mobilization occurs in early lactation, increasing the risk of ketosis. Reduces all muscle contraction including the teat sphincter muscle responsible for closure of the teat orifice after milking, thus increasing the risk of mastitis and also may increase the incidence of retained placenta, because of weaker uterus contractions to help expel the placenta.

More recently it was demonstrated hypocalcaemia directly impairs immune cell response to an activating stimulus. This is a very important finding. Until now all the emphasis was put on the relation between calcium and muscle and nerve control, but research from 2006, made by Dr. Kimura from the US National Animal Disease Center, showed a clear relationship between calcium levels and the immune system. This relationship is explained by the fact that calcium in the cells acts as a kind of messenger to early immune cell activation. If, as in early lactating cows, there is an increased demand for calcium this may adversely affect intracellular calcium stores of immune cells. This reduction in intracellular calcium stores in immune cells could blunt intracellular calcium release following an activating stimulus, contributing to the immune suppression seen in these animals. This may help to explain why calving and initiation of lactation in cows is associated with increased susceptibility to diseases such as mastitis, Johne’s disease, and Salmonellosis. In one experiment researchers surgically removed the mammary glands of periparturient cows and they showed that these cows do not develop hypocalcaemia and do not suffer from the same degree of immune suppression as intact, milk-producing periparturient cows.

Figure 1 shows very clearly the different relationships involved with calcium.

Figure 1 – Consequences of Milk Fever and Sub-Clinical Hypocalcaemia (Irish Veterinary Journal, 2006). Figure 1 – Consequences of Milk Fever and Sub-Clinical Hypocalcaemia (Irish Veterinary Journal, 2006).

February 2010 • Kenpal Dairy Brief • 3

Why do cows experience hypocalcaemia?

Calcium requirements for the dry cow are minimal, being necessary only for maintenance and fetal skeletal development. When the cow receives high amounts of calcium from the diet, her needs are met by passive absorption of calcium from the gut. That is, she doesn’t have to work hard to get it from the gut because her needs during the dry period are minimal. However, this is a disadvantage at calving because her ability to actively absorb calcium from the gut and mobilize calcium from bone is reduced. She must now actively pursue absorption of calcium from the gut, but because these mechanisms were not in use it takes a few days to reactivate them. Thus because she cannot respond quickly her blood calcium levels are depleted and milk fever develops. Normally a day or so is required for calcium mobilization mechanisms to become effective. Often by this time, hypocalcaemia and possibly milk fever already have occurred. Other minerals other than calcium are involved in this problem, namely potassium and in general all the minerals that are positively charged (cations) like sodium and magnesium. Overall they can cause a metabolic alkalosis (high blood pH) which interferes with the parathyroid hormone (PTH). In consequence, lack of PTH responsiveness by bone tissue prevents effective utilization of bone Calcium.

This knowledge about what causes hypocalcaemia is the key to the nutritional strategies involved in its prevention. We’ll discuss that in the next article.

References:“Parturition and Hypocalcemia Blunts Calcium Signals in Immune Cells of Dairy Cattle”. K. Kimura, T. A. Reinhardt, and J. P. Goff. J. Dairy Sci. 89:2588–2595, 2006.

“Production diseases of the transition cow: Milk fever and subclinical hypocalcaemia”. Finbar Mulligan, Luke O’Grady, Desmond Rice and Michael Doherty. Irish Veterinary Journal, Volume 59 (12) : December, 2006.

“The monitoring, prevention, and treatment of milk fever and subclinical hypocalcemia in dairy cows”. J.P. Goff. The Veterinary Journal 176 (2008).

“An Alternative to Metabolic Disorders; Looking at Hypocalcemia.”. Dairy Decision Column. Mike Hutjens, Extension Dairy Specialist. February 18, 2003.

“Metabolic Diseases - The Symptoms of a Greater Problem? “. Steve Radostits. 1995.

“Controlling Milk Fever and Hypocalcaemia in Dairy Cattle: Use of Dietary Cation-Anion Difference (DCAD) in Formulating Dry Cow Rations”. Technical Report 31. Greg Bethard, Extension Dairy Specialist, New Mexico State University, Rick Verbeck, Farmland Industries, Inc., John F. Smith, Extension Dairy Specialist, Kansas State University, 1998.

February 2010 • Kenpal Dairy Brief • 4

Cows, Stress and NutritionBy Pedro Nogueira

A major question confronting animal scientists is how to assess behavioral (or emotional) stress in livestock. Answering this question will assist us in making recommendations about the type of management schemes that will alleviate, or at least reduce, the impact that behavioural stress can have on the productivity and the health of domestic animals. Dr. Moberg, a researcher in this area also alerts that perhaps even more important, the ability to assess stress would provide us with the opportunity to address with scientific evidence the mounting public concern about the well-being of the animals used in production agriculture. This requirement to have scientific knowledge supporting codes and practices is recognized by the National Farm Animal Care Council of Canada. In their publication from 2009 “Code of Practice for the Care and Handling of Dairy Cattle” they specifically say “A key feature of NFACC’s Code development process is the inclusion of a Scientists Committee. It is widely accepted that animal welfare codes, guidelines, standards or legislation should take advantage of the best available knowledge. This knowledge is often generated from the scientific literature, hence the term “science-based”.

Stress can alter the flow of milk from several species of mammals. In dairy cows, stress during milking can reduce from 20 to 30% the amount of milk produced due mainly to the activity of the sympathetic nervous system. For example, when cows are milked in a new environment, they give less milk. This problem has been associated with hormonal changes (low oxytocin levels, and high prolactin and cortisol levels), which could be caused by the stress. In fact the mechanics of stress are a cascade of hormone releases and chemical signals. A signal is generated from either the external or internal source of stress, and through a series of steps ends up releasing stress hormones. Stress hormones such as cortisol, norepinephrine, and epinephrine are glucocorticoids. Glucocorticoids are elevated during a stress response and thus nonessential functions such as digestion are postponed. This causes animals to stop eating, lowering their ability to maintain weight and health. Studies showed that injections of the stress hormone corticotrophin (ACTH) and cortisol were responsible for reductions of 10 to 30% of the milk production for several days after injection. This helps to explain why cows sometimes take several days to fully adapt to new environments or handling procedures. It also tells us that we should try to eliminate the source of stress as soon as possible.

One of the reasons why transition cows are more susceptible to diseases has to do with higher circulating levels of these stress hormones around parturition. Dr. Overton, from Cornell University, made a study with 412 transition dairy cows from two New York dairies and concluded that cows with more postpartum health problems have greater pre-partum concentrations of metabolites associated with stress. Dr. Lorraine Sordillo, from Michigan University, also explains that the incidence of mastitis with respect to lactation stage is directly related to changes in the composition, magnitude, and efficiency of the mammary gland defence system. For example, physiological stresses associated with rapid differentiation of secretory parenchyma, intense mammary gland growth, and the onset of milk production, are accompanied by a high energy demand and an increased oxygen requirement. This increased oxygen demand augments the production of oxygen-derived reactants, collectively termed reactive oxygen species (ROS). The excessive accumulation of ROS can lead to a condition referred to as oxidative stress which is thought to be a significant underlying factor to dysfunctional immune and inflammatory responses that can increase the susceptibility of dairy cattle to a variety of health disorders, particularly during the transition period.

When levels of stress hormones are continually high, like for example in a severely overcrowded barn, stress can become chronic. Continued high levels of corticoids circulating in the blood interfere with the activity of the immune system by reducing lymphocyte and antibody production, can suppress the production of other hormones, such as folliclestimulating hormone (FSH), luteinizing hormone (LH), various growth hormones (GH) and thyroid stimulating hormone (TSH). This translates into decreased growth, lower milk

February 2010 • Kenpal Dairy Brief • 5con’t >>

production, lower conception rates and other metabolic diseases, all of which cost the producer. For example in humans chronic stress creates a host of problems, like high blood pressure and atherosclerosis.

Nutrition and immune system

The impact of nutrition on health is the subject of a significant body of research. This research has shown that nutrition can affect the ability of an animal’s immune system to fight a disease. A significant amount of research is being focused on the cellular and molecular processes affected by calcium and vitamins A and D. Calcium and vitamins A and D have been shown to have a significant effect on the functionality of immune cells. We also know that selenium and vitamin E play a role in the oxidative stress reactions, preventing problems associated with reproductive disorders, mastitis, and immune function.

One metabolic disease that has been associated with immune system disorder is hypocalcaemia or milk fever. Dr. Lipollis, from USDA Disease center, refers a study of over 2000 cows where it was shown that cows with hypocalcaemia were 8 times more likely to develop mastitis than cows with normal blood calcium levels. Contraction rate and strength of smooth muscle tissue have been shown to be directly related to the level of calcium in the blood. A current hypothesis is that even a sub-clinical hypocalcaemic cow would have decreased muscle tone in the smooth muscle that makes up the teat sphincter, and that this loss of muscle tone would cause the teat canal to remain partially open thus exposing the mammary gland to environmental pathogens. In addition to calcium’s critical role in muscle function, it also plays an essential role at the cellular level. In immune cells, intracellular calcium regulates many cellular functions. A deficient intracellular calcium response would have a significant effect on the functional capacity of the cells of the immune system. So in case you are experiencing high incidence of mastitis in fresh cows, maybe you should review your dry cow diet.

The immune system is affected by various non-pathogenic stimuli and has an important role in processes other than disease control. For example, as Dr. Lipollis explains, the immune system plays an important role in the maintenance of the corpus luteum. Therefore, the immune system plays an important role in reproduction. In addition, non-pathogenic stimuli such as stress can after prolonged exposure have a suppressive effect on the immune system and make the animal susceptible to infection.

This relationship between nutrients, immune system, production, reproduction and health informs us that optimal diets must be given to ensure proper immune function, and stresses must be reduced to eliminate suppression of the immune response. If for some reason the condition in your barn are not optimal (overcrowding, renovations, changing of routines, changing of people, poor comfort) you should consider increasing the levels of the mineral/vitamin package you are feeding, eventually add some organic mineral sources and also review the level of energy of the diet. This will hopefully help to strengthen the immune system and help the cow cope with those challenges.

References:

“Code of Practice for the Care and Handling of Dairy Cattle” National Farm Animal Care Council (NFACC), Dairy Farmers of Canada - 2009“ Measurements of fear in dairy cattle: a review of latest findings.” By Sally Jayne Coggins“A Model for Assessing the Impact of Behavioral Stress on Domestic Animals.” Gary P. Moberg. J Anim Sci 65:1228-1235,1987. “Understanding the Relationship Between Immunity and Dairy Cow Production”. J. D. Lippolis Periparturient Disease of Cattle Research Unit National Animal Disease Center, ARS, USDA.“Vos Vaches : Leurs Peurs et Votre Portefeuille”. Jeffrey Rushen and Anne-Marie B. de Passillé. 1997.

February 2010 • Kenpal Dairy Brief • 6

February 2010 • Kenpal Dairy Brief • 7

Contact your Silo Guard II Representative

today For MORE INFORMATION!INTERNATIONAL STOCK FOOD Centralia, OntarioTel. 519-228-2190Toll Free 1-877-473-2474Fax 519-228-2195info@isfcanada.cawww.isfcanada.ca

KENPAL FARM PRODUCTSCentralia, OntarioTel. 519-228-6444Toll Free 1-800-265-2904Fax 519-228-6560kpalen@kenpal.on.cawww.kenpal.on.ca

69819 London Road, RR #1, Centralia, Ontario, Canada, N0M 1K0 Tel: (519) 228-6444 or 1-800-265-2904 • Fax (519) 228-6560 • Email kpalen@kenpal.on.ca • www.kenpal.on.ca

Published by:

WE APPRECIATE YOUR BUSINESS

© Kenpal Farm Products Inc. Revised 11/09™ Trademark of Kenpal Farm Products Inc. 11/09 PRINTED IN CANADA

®

Specialty Feed Products•

Vitamin & Mineral Premixes•

Lacta-Fat liquid fat•

Liquid Molasses blend•

STARTline including drySTART ™ • (drying agent for livestock & poultry facilities)

International Stock Food (ISF) - • Specialty livestock feed products

Silo Guard®II Forage Additive (dry and • liquid)

Providing Products to the Livestock Industry since 1983• Feed Assure™ (HACCP) Certified since 1999 (First in Canada)• Family owned company doing business with family principles•

Livestock Supplier of:

the

line TM