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0109 PD: Early life management and long-term productivity of dairy calves

Mike Van Amburg, E. Raffrenato and F. Soberon Published on 23 December 2008
The topic of “intensified feeding or accelerated growth” has garnered a great deal of discussion, and the concept has been applied in both research and on-farm trials in various ways. Much of this discussion involves differences in perspectives about how to best manage the nutrition and nutrient intake and weaning of the calf.

There are teleological arguments for providing a greater supply of nutrients from milk or milk replacer, and there are also arguments for improving welfare status by following the same concept. The calf has a requirement for maintenance and once maintenance requirements are met, growth can be achieved if enough nutrients and the proper balance of nutrients are provided to the calf. The nutrient requirements of the calf have been described in the current Nutrient Requirements of Dairy Cattle 7th Ed. (National Research Council [NRC], 2001) publication.

The requirements can be easily actualized and are very useful for diagnosing the impact of temperature on the maintenance requirements of the calf through the computer program that accompanies the publication. New data are now available that help us refine those predictions. Table 1 (page 11) summarizes our current knowledge about the requirements for growth of the calf based on the body composition data derived since the 2001 NRC was published.

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These values are consistent with the current publication, but have slightly lower energy requirements per unit of gain because the original equations were based on heavier veal- type calves fed higher fat diets and depositing more fat per unit of weight gain. These predictions for energy requirements are consistent with dairy replacement calves being fed diets more typical of our system.

The protein requirement is higher than the NRC publication due to an updated efficiency of use calculation. The 2001 NRC calculations suggested that absorbed protein was used with an efficiency of 0.80, whereas our latest calculations suggest the efficiency is closer to 0.70, thus the requirements are 10 to 12 percent higher than the 2001 predictions.

These requirements are interesting because they reinforce the idea that what the cow would normally provide to the calf is the appropriate combination of protein and energy required by the calf. Thus, many milk replacers are not really replacing milk because they don’t contain the same nutrient levels and they are rarely fed to equal the nutrient intake of whole milk. It further suggests that least-cost milk replacer formulations should not be expected to provide much beyond maintenance energy.

However, to further this idea of nutrient status, data are available and emerging that suggest factors such as colostrum status and energy balance up to at least eight weeks of age have long-term carryover effects that can be measured in the first lactation. Just like other neonates, it appears that calves might be affected by early-life events and that “compensatory mechanisms” really don’t exist for this stage of development.

It also suggests that we need to alter how we view this stage of development, especially as it relates to future productivity. This concept and data to support it is still being developed, but there appears to be a positive relationship with early-life nutrient intake.

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Early development and productivity
Colostrum status
To maximize calf survival and growth, plasma immunoglobulin (Ig) status and thus colostrum management is of utmost importance.

This is obviously not a new concept and there are hundreds of papers describing the management and biology surrounding colostrum quality, yield and Ig absorption by the calf although some recent research on colostrum handling and management suggest we can still make improvements. Of interest are the studies that have described decreased growth rate and increased morbidity of calves with low serum Ig status and some have even indicated that milk yield during first lactation can be affected.

Robison et. al., indicated that calves with higher Ig status are able to inactivate pathogens prior to mounting a full immune response which allows them to maintain energy and nutrient utilization for growth, whereas calves with low Ig status must mount an immune response which causes nutrients to be diverted to defense mechanisms. How severe is this difference or for how long does it persist? The data of DeNise et al. demonstrated that for each unit of serum immunoglobulin G (IgG) content, measured at 24 to 48 hours after administration, above 12 milligrams per milliliter, there was an 18.7-pound increase in mature equivalent milk.

The implication is that calves with lower IgG content were more susceptible to immune challenges which impacted long-term performance. As with all longitudinal and epidemiological studies there are inconsistencies. Donovan et. al. found indirect effects of colostrums status on growth and performance of calves but concluded it was due to increased morbidity and not a direct effect. A similar observation was made by Wittum and Perino in beef calves where they measured a 24-pound lower weaning weight of calves with failure of passive transfer but suggested it was due to increased morbidity and not a direct effect.

A more recent study suggested that impact of serum Ig levels was not nearly that great, but it did affect milk yield and survival through the second lactation. Brown Swiss calves were provided either two or four liters of colostrum just after birth. The calves were monitored after calving for two lactations. At the end of the second lactation three major observations were made. First, there was a 30 percent increase in prepubertal growth rates based on colostrum feeding level, under identical feeding conditions. Second, there was a 16 percent increase in survival to the end of the second lactation of calves fed the four liters of colostrum. Finally, the surviving calves fed the four liters of colostrum produced 2,263 pounds more milk by the end of the second lactation.

Although somewhat subtle, these differences suggest that early-life colostrum status is important for long-term productivity. If part of the mechanism is related to maintaining nutrient partitioning towards growth via high Ig status, then the concept of nutrient status should also demonstrate responses beyond the Ig status of the calf.

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Nutrient status and long-term productivity
There are several studies in various animal species that demonstrate early-life nutrient status has long-term developmental effects. For a more extensive discussion of this topic, a recent review of these concepts was conducted by Dr. Jim Drackley. Aside from the improvement in potential immune competency, there appears to be other factors that are impacted by early-life nutrient status.

There are several published studies and studies in progress that have both directly and indirectly allowed us to evaluate milk yield from cattle that were allowed more nutrients up to eight weeks of age. The earliest of these studies investigated either the effect of suckling versus controlled intakes or ad-libitum feeding of calves from birth to 42 or 56 days of life. In each of these studies, increased nutrient intake prior to 56 days of life resulted in increased milk yield during the first lactation that ranged from 1,000 to 3,000 additional pounds compared to more restricted fed calves during the same period.

Although they are suckling studies, milk is most likely not the factor of interest, but nutrient intake in general and this is demonstrated in the more recent data. In the study conducted at Miner Institute, Ballard et. al., reported that at 200 days in milk, the calves fed milk replacer at approximately twice normal feeding rates produced 1,543 pounds milk more than the calves that received one pound of milk replacer powder per day. Calving age in that study was not affected by treatment. Overall, averaging the studies, there is a 1,700-pound response to increasing nutrient intake prior to weaning.

The significant point is that it appears this effect of intake level needs to be accomplished through liquid feed intake. The response in the study of Moallem et. al. is significant, specifically because it suggests that milk replacer quality is important to achieve the milk response, as is protein status of the animal postweaning. In that study, the calves were fed a 23 percent crude protein (CP), 12 percent fat milk replacer containing soy protein or whole milk. Further, at postweaning the calves were fed similarly until 150 days of gain, and the diets were protein-deficient (~13.5 percent CP).

Starting at 150 days, calves from both pre-weaning treatments were supplemented with 2 percent fish meal from 150 to 300 days of life. The calves allowed to consume the whole milk (ad lib for 60 minutes) and supplemented with the additional protein produced approximately 2,500 pounds more milk in the first lactation indicating that the early life response could be muted by inadequate nutrition and management postweaning. Finally, the data of Pollard et. al. again demonstrates a positive response of early-life nutrition on first-lactation milk yield. In this study calves were fed either a conventional milk replacer (22:20) at 1.25 percent bodyweight (BW) or a 28:20 milk replacer fed at 2 percent BW for week one of treatment and then 2.5 percent BW from week 2 to 5 and then systematically weaned by dropping the milk replacer intake to 1.25 percent for 6 days and then no milk replacer.

All calves were weaned by seven weeks of age and after weaning all calves were managed as a single group and bred according to observed heats. The heifers calved between 24 and 26 months of age with no significant difference among treatments. Calving weights were also not different and averaged 1,278 pounds. Milk yield on average was 1,841 pounds greater for calves fed the higher level of milk replacer prior to weaning. We are nearing the end of a similar study, but our lactation data is too preliminary to make evaluations. However, the Cornell T&R Dairy started feeding for greater pre-weaning weight gains many years ago and have over 1,000 weaning weights and 725 lactations with which to make evaluations outside of our ongoing study.

Utilizing a Test Day Model (TDM), we analyzed the lactation data of the 725 heifers with completed lactations and ran regressions on several factors related to early-life performance and the TDM milk yield solutions. Factors analyzed were birth weight, weaning weight, height at weaning, weight at four weeks of age and several other factors. What was most interesting and consistent with the data was that the greatest correlation with first-lactation milk production was growth rate prior to weaning. In our data set, for every one pound of average daily gain (ADG) prior to weaning, the heifers produced approximately 1,000 pounds more milk. The range in pre-weaning growth rates among the 725 animals was 0.52 to 2.76 pounds per day.

Further, 20 percent of the variation in first- lactation milk production could be explained by growth rate to weaning. This suggests that the impacts of Ig status and nutrient intake are playing a significant role in the performance and variation in first-lactation milk yield. Regressions of the lactation data from these studies and the growth rates, when controlled for study, suggest that to achieve these milk yield responses from early-life nutrition, calves must double their birth weight or grow at a rate that would allow them to double their birth weight by weaning (56 days). This further suggests that milk or milk replacer intake must be greater than traditional programs for the first three to four weeks of life in order to achieve this response.

What changes in the animal are allowing for these differences? There is no one answer to that question but investigations are looking for several factors. Although mammary development as has been measured is probably not the appropriate factor, it is intriguing to look at very specific cells within the mammary gland. There are a couple sets of data that demonstrate increased mammary cell growth based on early-life nutrient intake. Brown et. al. observed a 32 to 47 percent increase in mammary DNA content of calves fed approximately two versus one pound of milk replacer powder per day through weaning.

Just like the milk production increases discussed earlier, this mammary effect only occurred prior to weaning. In fact, this increase in mammary development was not observed once the calves were weaned, indicating the calf is more sensitive to levels of nutrition prior to weaning and that the enhancement mammary development cannot be “recovered” once we wean the animal.

Meyer et. al. observed a similar effect in mammary cell proliferation in calves fed in a similar manner. The calves on his study demonstrated a 40 percent increase in mammary cell proliferation when allowed to consume at least twice as much milk replacer as the control group prior to weaning. Sejrsen et. al. observed no negative effect on mammary development in calves allowed to consume close to ad libitum intakes.

A more specific attempt to look at stem cell proliferation did not find increased stem cells in calves fed higher levels of nutrient intake, and it was hypothesized that the stem cell proliferation might lead to greater secretory cells once the animal becomes pregnant.

Summary
Early-life events appear to have long-term effects on the performance of the calf. Our management approaches and systems need to recognize these effects and capitalize on them.

Obviously we have much to learn about the consistency of the response and the mechanisms that are being affected. However, it appears that there is some potential profit in spending more time and resources on the animal at this early stage of life. PD

References omitted but are available upon request at

—Excerpts from 2008 Cornell Nutrition Conference Proceedings

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