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0308 PD: New insights into managing the neonatal calf for health and production

Jerry D. Olson Published on 04 February 2008

The National Animal Health and Monitoring System (NAHMS) has conducted three surveys in 1991, 1996, and 2002, of U.S. dairies that includes information on health and management practices involving dairy calves. The pre-weaning mortality rates ranged from 8.4 to 10.8 percent in these surveys.

The NAHMS (1994) survey data also indicate that morbidity rate for preweaned calves is approximately 37 percent.

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In the 1996 survey, 60 percent of the pre-weaning deaths were attributable to scours and 25 percent to respiratory infections. Sixty-two percent of the calf deaths occurred in the first three weeks following birth. Failure of passive transfer has long been recognized as an important factor contributing to calf morbidity and mortality.

In 1994, NAHMS reported that 41 percent of 2,177 calves sampled for determination of serum immunoglobulin (IgG) concentrations had failure of passive transfer (FPT) characterized by IgG concentration of less than 1 gram per deciliter (gm/dl). Wells (1996) has estimated that 31 percent of the dairy heifer pre-weaning deaths could be prevented through improved colostrum feeding methods including timing and volume of the first colostrum. In addition to colostrum management, the risk of calf mortality increases as the amount of time that the calf is left with the dam after birth increases and as the difficulty of calving increases.

The value of good colostrum management extends beyond just a reduction in calf mortality and morbidity. Faber reported on the effects of feeding two versus four quarts of colostrum to Brown Swiss calves on health costs, rates of gain and milk production over the first two lactations. The calves were managed the same way in all respects except for the difference in the amount of first colostrum fed.

The calves fed four quarts of colostrum gained 0.5 pounds per day more from age at weaning to breeding and weighed 170 pounds more at breeding age than calves receiving two quarts. The calves fed four quarts of colostrum produced two more pounds of milk per day during their first two lactations compared to calves receiving two quarts. In addition, treatment costs for calf diseases were reduced by $9.74 per calf for the calves receiving four quarts of colostrum.

The collective values of feeding four quarts of colostrum in reduced mortality, reduced treatment costs, improved rates of gain and larger size calves at breeding and improved production suggests that a gallon of colostrum is worth about $400.

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Guidelines for colostrum management
The key factors affecting successful colostrum management for calves are the following:

1. the timing of the first feeding

2. the quality of colostrum

3. the volume of colostrum fed

4. pathogen and bacterial contamination of colostrum

Timing of the first colostrum feeding
At birth, the calf’s intestine has a finite capacity to absorb large molecules directly from the intestinal lumen and transfer them to the blood. This capacity is rather indiscriminant with respect to the type of large molecules that are absorbed and is gradually lost over the first 24 hours of life, which is lost more quickly following ingestion of colostrum or milk.

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With that said, if the feeding of colostrum is delayed until more than six hours after birth, the proportion of calves experiencing FPT increases. Therefore, the first feeding of colostrum should be completed within the first six hours of birth.

Quality of colostrum
The immunoglobulin concentration in colostrum is the primary factor affecting quality. To prevent FPT, calves need to consume about 100 grams (gm) of immunoglobulin. A calf consuming four quarts of colostrum containing a minimum of 3.5 gm/dl of immunoglobulins, will get about 100 gm of immunoglobulin.

Colostrum with immunoglobulin concentrations of less than 3.5 gm/dl are usually considered to be of poor quality, with about 30 percent of colostrums falling into this category. A colostrometer is an effective tool for screening colostrums to identify the poor-quality colostrums. The colostrometer, if used properly, will identify about 50 percent of the poor- quality colostrums, which can then be avoided for feeding calves.

Other management factors that can be used to improve colostrum quality include milking fresh cows as soon as possible after freshening and avoiding pooling colostrums. Moore, et al. has shown that as the interval between calving and collection of colostrum increases, the immunoglobulin concentration in colostrum decreases. Cows that were not milked until 14 hours after calving had colostrum with a third less immunoglobulin concentrations compared to those milked within two hours of calving.

It is speculated that immunoglobulins are being reabsorbed from colostrum after calving, thus lower immunoglobulin concentrations with increasing interval before harvest. Pooled colostrum batches have lower immunoglobulin concentrations than the average of the individual colostrums contributing to the pool because cows producing the largest amounts of colostrum have colostrums with the lowest immunoglobulin concentrations.

Immunoglobulin concentration in colostrum from first-lactation cows does not vary significantly from second and greater lactation cows. Therefore, colostrum from first-lactation cows is acceptable for feeding calves.

Amount of colostrum fed
Based on the variation in the concentration of immunoglobulin in colostrum, it is recommended that the first feeding of colostrum should be one gallon to compensate for the colostrums with low immunoglobulin concentrations.

Bacterial and pathogen contamination of colostrum
Two other factors that affect the quality of colostrum and milk are the levels of either environmental bacteria contamination or pathogens. The pathogens of primary concern that can occur in colostrum and milk are salmonella, Mycoplasma, and Johne’s bacteria. These pathogens can be shed into colostrum and milk and can be a source of infections for calves.

In addition, pooled colostrums increase the risk that the pooled batches of colostrum or milk can be contaminated with these pathogens for a single infected cow contributing to the pool. Pasteurization of colostrum at a temperature of 145ºF for 30 minutes for the elimination of these pathogens has been a problem in that pasteurization tends to destroy immunoglobulins and causes colostrum to attain a pudding-like consistency.

Godden, et al., has demonstrated that pasteurizing colostrum at 140ºF for 30 minutes can eliminate the pathogens of concern and does not destroy the immunoglobulins. In fact, calves fed colostrum pasteurized at 140ºF for 30 minutes had better serum immunoglobulin levels than calves fed non-pasteurized colostrum. It was speculated that bacteria in the non-pasteurized colostrum may have occupied sites for macromolecule absorption in the small intestine, leading to exclusion of immunoglobulins.

High bacterial levels in colostrum or milk can be the result of either poor sanitation practices in milking cows, ineffective cooling of colostrum between the time colostrum is collected and fed, or bacterial contamination of utensils holding colostrum. Calves fed colostrum or milk with high levels of bacteria, have higher morbidity.

Take-home messages

•The first feeding of colostrum needs to be done within six hours of birth.

•Calves need to be fed first-milking colostrum from either first-lactation or older cows. A colostrometer can be used to screen and eliminate half of the poor-quality colostrums.

•The current recommendation is to feed one gallon of colostrum.

•First-milking colostrum should be collected cleanly, and if not fed immediately, cooled and stored in a refrigerator to prevent bacterial contamination.

•Avoid pooling colostrum as this practice increases the chances of spreading Johne’s, Salmonella, and Mycoplasma to all calves fed from a pooled batch. Pooled colostrum batches have lower IgG levels than the average of individual samples contributing to the pool.

•Pasteurization of colostrum at 140ºF for 30 minutes effectively eliminated pathogens, lowered bacteria counts and did not damage IgG.

Post-colostrum feeding guidelines
For fifty years the dairy industry has followed the recommendation that calves be fed one pound of milk replacer in a gallon of water until weaning. The concept behind this restricted feeding of milk replacer was that calves would be hungrier and they would begin consuming calf starter sooner. Since calf starter is about one-fifth the cost on a per pound basis of milk replacer, the end result would be a more economical program for growing calves.

This feeding practice has recently received several critical reviews. Neonatal calves when allowed ad libitum access to a liquid diet of milk or milk replacer, will consume 16 to 24 percent of their bodyweight (BW) per day by the third to fourth week of life, which is substantially more than the 10 to 12 percent of BW commonly fed to Holstein calves consuming one pound of a 20 percent protein, 20 percent fat milk replacer (20:20 MR) in a gallon of water.

Calves consuming one pound of a 20:20 MR have enough energy to remain in a positive energy balance until environmental temperatures drop below 50 to 60ºF. Below these temperatures they must use body tissue to meet energy needs and will lose weight if they are not consuming adequate calf starter to complement the energy from the milk replacer.

One of the companies manufacturing milk replacer reported that large Holstein bull calves lost an average of 0.25 pounds per day the first week of life and an average 0.8 pounds per day the second week of life. Only when calves begin consuming calf starter in the third week of life did calves start to have a positive weight gain.

There is awareness that the immune system needs adequate levels of certain trace minerals and vitamins to function, but often there is failure to appreciate the importance of adequate energy for immune function. The National Dairy Heifer Evaluation Project reported that 62 percent of pre-weaning calf deaths occurred within the first three weeks following birth, the same period of time when calves were adjusting to extra-uterine life and were losing weight.

All this information suggests that if calves were fed to a higher plain of nutrition the first two to three weeks of life, calf morbidity and mortality could be reduced. Nonnecke and Foote have shown that there was no difference in immune function of calves consuming a 20:20 MR at 1.4 percent of their bodyweight (BW) per day versus a 30:20 MR at 2.5 percent of BW as long as the calves were in thermoneutral environment and in a positive energy balance characterized by weight gain.

Godden, et al. reported on a study comparing the effects of feeding milk replacer versus feeding pasteurized discard milk on growth rate, morbidity and mortality in calves. The calves in the milk replacer group were fed one pound of a non-medicated 20:20 MR in one gallon of water divided into two daily feedings. The calves in the pasteurized milk group were fed one gallon of pasteurized discard milk daily.

Calves fed pasteurized discard milk had significantly higher rates of gain (0.26 pounds per day), higher weaning weights (12.3 pounds) and lower morbidity and mortality rates than cohorts. The calves fed the milk replacer were at higher risk of treatment for diarrhea and pneumonia during the summer (12.7 versus 4.4 percent) and winter (52.4 versus 20.4 percent) months, respectively, and higher risk of death during the winter months (21 versus 2.8 percent) and overall months (11.6 versus 2.2 percent), respectively.

The overall mortality rate for the milk replacer calves was 11.6 percent, which is within the range of mortality reported in the NAHMS studies. This overall mortality for calves fed milk replacer was significantly higher than the 2.2 percent mortality for calves fed pasteurized milk. The overall morbidity risk was significantly higher for calves born in the winter months than in the summer months. Morbidity risk was significantly higher for calves fed milk replacer during both seasons, with the incidence of scours being significantly higher for the milk replacer calves compared to the calves fed discard milk (17.2 vs. 3.1 percent).

One difference between the two programs is that the calves fed milk replacer consumed 2.15 Mcal ME per day in one pound of a 20:20 milk replacer while the calves consuming discard milk consumed 2.44 ME per day, about 13.5 percent more ME energy per day.

Take-home messages

•Feeding inadequate amounts of milk or milk replacer to meet the energy needs of the calf puts the calf at increased risk of disease and death.

•Morbidity and mortality were higher in the winter months for the calves fed milk replacer, when the energy deficiency of these calves would have been the greatest.

•There does not appear to be an enhancement of immune function by feeding more milk replacer as long as the calf is in a positive energy balance.

Determining calves’ protein, energy needs
The first “nutrient” need of the calf is energy for maintenance functions. Once maintenance energy needs are met, any additional energy consumed can be partitioned for growth. The primary factors affecting the energy needs of the calf for maintenance are the size of the calf and environmental temperature. The 2001 NRC Nutrient Requirements for Dairy Cattle contains ration evaluation software which can be used to evaluate the adequacy of various calf feeding programs relative to the needs of the calf based on size of the calf and environmental temperatures.

Within breed, there is greater variation in energy needs relative to the range of environmental temperatures than body size. The lower critical temperature for Holstein calves is between 65 to 70ºF. As environmental temperatures decline below the lower critical temperature, energy requirements for maintenance increase and at 50ºF the energy requirements for maintenance exceed the energy provided by one pound of a 20:20 MR.

The upper critical temperatures are less clearly defined for the calf and the NRC model does not show increases in maintenance energy requirements with elevated environmental temperatures. Once energy needs for maintenance have been met, any additional energy will be used for growth. How that additional energy is used will be determined by the availability of protein. If sufficient protein is available, the energy will be used for the production of lean tissue. If insufficient protein is available, the energy will be used for the deposition of fat.

Once the energy requirement for maintenance has been determined based on the size of the calf and the environmental temperature, the desired rate of gain becomes the third determinant of the amount of energy that needs to be fed in addition to that required for maintenance. Like any other class of livestock, the amount of energy that a calf consumes is a function of the amount of dry matter consumed and the energy density of the dry matter. Milk replacers are reconstituted in the range of 10 to 17.5 percent dry matter and are fed at the rate of 8 to 18 percent of bodyweight of the calf. This means a ninety-pound calf could consume between 0.7 and 2.8 pounds of dry matter, depending upon rate of reconstitution and percent of bodyweight that the milk replacer is fed.

The energy density of a milk replacer is primarily dependent upon the fat content. Commercial milk replacers range from 10 to 20 percent fat. If whole milk with a 3.5 percent fat content were dried and packaged in a bag, it would have a fat content of about 30 percent. The point is that when milk replacer is purchased, one should compare milk replacers on the basis of cost of a megacalorie of metabolizable energy.

Once the size of the calf and environmental temperatures have been established to determine the energy requirements of the calf, the amount of milk replacer should be determined to maintain the calf in a positive energy balance. Four studies have looked at the effect of feeding nutrients at 50 percent or greater than standard level of feeding to calves on milk production in the first lactation. The heifers on the higher plain of nutrition produced between 1,000 and 3,000 pounds more milk than their contemporaries in the first lactation.

Take-home messages

•Calf morbidity and mortality can be reduced by making sure calves are getting enough energy to be in a positive energy balance.

•Calves fed at levels of 50 percent or greater above standard levels of intake have produced between 1,000 and 3,000 pounds more milk in their first lactation. PD

References omitted but are available upon request at

—Excerpts from 18th Annual Colorado Dairy Nutrition Conference Proceedings

Jerry D. Olson, DVM, Senior Veterinarian, Pfizer Animal Health

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