Scientists from around the globe presented the results of their most recent research at the joint annual meeting of the American Dairy Science Association and the American Society of Animal Science last month in Kansas City, Missouri. This article highlights some of the latest findings related to feeding and managing dairy calves.
Calf Research Updates

Alternatives to Tincture of Iodine for Navel Dips

A report from Iowa State (Robinson et al.) showed that several products can be effective as navel dips for newborn calves. Ever since tighter federal regulations have limited the availability of 7% tincture of iodine, alternatives to this conventional navel dip have been explored on-farm and recommended by farm advisors. But there is very little research data on which to base these recommendations. The Iowa State study compared 7% tincture of iodine, a 1,000 parts per million (ppm) chlorine solution (ECAlogix System, marketed by Zurex PharmAgra, LLC), chlorhexidine, and ZuraLac (marketed by Zurex PharmAgra, LLC) as navel dips for 60 Jersey calves. The diameter of each umbilical cord was measured before being dipped (within 30 minutes of birth) and again 24 hours later. The surface temperature was also measured with an infrared thermometer as an indicator of infection. The umbilical diameter was approximately 0.90 ± 0.15 inch at birth and 0.30 ± 0.16 inch 24 hours later, with no differences between the four dips and no evidence of infection in any of the calves.

Heat Treatment and Bacteria Levels in Colostrum

Penn State researchers (Gelsinger and Heinrichs) presented results from a study investigating colostrum bacteria content and its effects on absorption of IgG and health in calves. One hundred four calves were fed one of four colostrum treatments: unheated, low bacteria; unheated, high bacteria, heat-treated, low bacteria; or heat-treated, high bacteria in a single 1-gallon feeding. All colostrum was from the same initial pool. Heat-treated colostrum was processed for 30 minutes at 140°F. Heat-treated, high bacteria colostrum was inoculated with 20 mL of the unheated colostrum and the two high bacteria treatments were held at 68°F to allow bacteria to multiply. Standard plate counts were 4.59, 8.65, 2.79, and 8.56 log CFU/mL and coliform counts were 3.78, 6.91, 0.00, and 7.31 log CFU/mL for the unheated, low bacteria; unheated, high bacteria; heat-treated, low bacteria; and heat-treated, high bacteria treatments respectively. Colostrum IgG content was similar for the treatments and averaged 69 mg/mL. Calves fed colostrum with high bacteria counts had lower plasma total protein (7.3 vs 8.4 g/dL) and IgG (9.4 vs 22.3 mg/mL) at 48 hours and reduced efficiency of IgG absorption (14.3 vs 34.8%) compared to calves fed low bacteria colostrum. Unlike previous work, this study failed to detect a statistical improvement in plasma total protein, IgG, or absorption efficiency when colostrum was heat-treated, but these values were numerically greater for calves fed heat-treated colostrum compared to those fed unheated colostrum. In addition, calves fed heat-treated, low bacteria colostrum tended to have fewer days with scours in the first week of life than calves fed any of the other treatments.

This study provides additional support for the importance of controlling bacterial content of colostrum fed to newborn calves. Heat treatment can be very effective in reducing bacteria numbers, but if colostrum is contaminated after treatment the benefit is lost.

Evaluation of Autofeeders on Midwestern Farms

Automated calf feeding systems on 38 Midwestern farms were evaluated in a study by the University of Minnesota (Jorgensen et al.). Farms were visited every 60 days over 18 months and more than 10,000 individual calves were assigned health scores. Blood samples were collected from calves 1 to 5 days of age at the time of the farm visit to evaluate passive transfer of immunity. Milk samples were collected from the calf feeder in the milk mixing container and in the milk line leading to the nipple. Results varied tremendously between farms, indicating that the level of management has huge impact on the performance of calves with an autofeeding system. Table 1 presents the percentage of calves that received abnormal health scores in each category with the results grouped by the 10 farms with the healthiest calves and the 10 farms with the least healthy calves. Categories evaluated included attitude, ears, nose, eyes, and cleanliness (an indicator of scours).

Table 1. Percent of calves fed by automated feeders in group housing that received an abnormal health score in 5 different categories. Average and range of health scores are presented for the 10 farms with the best health scores and the 10 farms with the worst health scores (out of 38 farms evaluated).

Top 10 Farms Bottom 10 Farms
Average Min Max Average Min Max
Attitude 9.7 2.9 12.9 22.8 15.7 30.3
Ears 3.7 1.7 5.1 14.4 10.0 22.5
Nose 12.2 7.8 14.8 27.2 22.8 30.6
Eyes 7.2 2.0 11.9 30.3 22.5 36.4
Cleanliness 26.4 20.1 32.6 54.9 50.6 60.3

Approximately one-third of the calves tested had serum protein levels below 5.2 g/dL, and 9 of the 38 farms had a farm average of less than 5.2 g/dL. Bacteria counts were highest in the tube, and increased standard plate count in the feeder tube was associated with an increase the number of calves with abnormal scores for cleanliness. Colostrum management, cleaning of the feeding system, grouping strategies, evaluation of calf performance, and housing design and maintenance are all potential factors that contribute to the success of automated feeding. Like any other management system, the autofeeder will work best when all the components of the system are given proper attention.

Feeding Frequency

Feeding frequency was investigated in two studies presented at the meetings. The first, conducted at Mississippi State (Ward et al.), compared 53 calves fed 2 or 3 times per day and housed either in pairs or individually. Calves were fed 1.5 gallons per day of whole milk and weaned at 8 weeks of age. The trial continued through 10 weeks of age to evaluate the post-weaning period. Calf starter was available beginning at 3 days of age. Over the 10-week trial there was no effect of feeding frequency on body weight or average daily gain. However, after weaning calves fed twice a day and housed individually grew at a faster rate than the other treatments. Feeding frequency did not affect starter intake, but calves housed in pairs tended to eat more grain than those housed individually.

The second study on feeding frequency was undertaken by scientists at Louisiana State University (Thomas et al.), who fed 63 calves 1, 2, or 3 times per day. In this trial all calves received milk replacer (20% protein, 20% fat; mixed at 15% solids) at a rate of 10% of birth weight, divided equally among their assigned number of feedings. Calves were weaned at 42 days of age, starter was available from 3 days of age, and the trial ended at 56 days of age. Feeding frequency had no effect on starter intake, calf body weight, average daily gain, withers height, hip height, or hip width. In addition, no differences were observed in blood glucose, urea nitrogen, or beta-hydroxybutyrate measured at 14, 28, 42, and 56 days of age.

In summary, calves on a conventional milk replacer program performed similarly whether provided their daily allotment of milk in 1, 2, or 3 feedings per day. When fed on a slightly higher plane of nutrition, calves fed whole milk 2 or 3 times a day also showed no effect of feeding frequency on calf performance.

Alternative Protein Sources for Milk Replacer

Less expensive alternatives for milk proteins in calf milk replacer have long been sought. In many cases these proteins have been found to have lower nutritional value for the calf and a typical recommendation is that only products containing all-milk proteins be fed to calves less than 3 weeks of age. Alternative proteins have been seen as a cost-effective option for older calves, with the expectation that performance may be somewhat less than that possible with an all-milk protein milk replacer. New processing methods and new protein sources (plasma) may be challenging that conventional wisdom.

University of Minnesota researchers (Ziegler et al.) evaluated 4 milk replacers with different protein sources; alternative proteins replaced 50% of total protein in the feeds tested. Treatments were: all-milk protein; wheat and plasma; soy protein concentrate and plasma; or wheat, soy protein concentrate, and plasma. All milk replacers were non-medicated, formulated at 20% protein, 20% fat and fed at 1.25 pounds of powder per day (12.5% solids) in 2 feedings for 35 days. Milk replacer was reduced by half beginning at day 36 and calves were fully weaned at day 42. Calf starter was available beginning from day 1, and measurements continued through 56 days.

No differences were detected in grain intake, average daily gain, body weight, or hip height. Feed efficiency during the milk feeding period was greater for calves fed protein from wheat and plasma compared to the other alternative proteins, but it was similar to the all-milk protein replacer. Feed efficiency after weaning was lower for calves fed all-milk protein compared to those fed soy protein concentrate and plasma or wheat, soy, and plasma. When feed efficiency was calculated over the entire trial, no differences between treatments were found. Fecal scores and scour days were higher for all-milk calves, which the researchers attributed to the use of plasma protein in all of the alternative milk replacers. Previous research has shown that plasma proteins have functional benefits to the immune system beyond their use as a source of amino acids. Treatment costs for illnesses were not affected by milk replacer protein source.

Solids Content of Milk Replacer

Scientists at Provimi’s Nurture Research Center (Quigley et al.) presented the results of a study designed to evaluate the impact of milk replacer solids content on calf performance. Typically, milk replacer is fed at 12.5% solids, which is similar to the solids content of whole milk. Increasing the amount fed to calves during the winter months is a proven method of maintaining calf growth during cold weather. However, if a farm uses bottles or buckets that limit the ability to increase the volume of milk fed, increasing the solids content can enable more nutrients to be fed in the same container.

In this study, 48 calves were fed 1.38 pounds per day of milk replacer powder through day 35, followed by half that amount through weaning at 42 days. Calf starter was available throughout the study. Powder was mixed with different volumes of water to create 4 treatments with solids contents of 10%, 12.5%, 15%, or 17.5%. No effect of the solids content was observed for starter intake, body weight, hip height, body condition score, or feed efficiency. The number of days with an abnormal fecal score declined linearly with increasing solids content; however, the incidence of abnormal fecal scores was much greater during the first 2 weeks of the trial than in later weeks. Calves fed larger volumes of milk replacer may have had an increased flow rate of digesta leaving the abomasum and entering the intestine, which could have influenced the volume of diarrhea. Water intake was not measured in this experiment, but it is also possible that calves fed their milk replacer in the largest volumes of water may have had more water in their system available for excretion, leading to higher volumes of diarrhea.

In this report, increasing the solids content of milk replacer up to 17.5% did not affect intake or growth and may have had a positive influence on health, which suggests that increasing the solids content to accomplish higher feeding rates using fixed-volume feeding equipment is a viable strategy.

Lying Behavior

There were numerous presentations related to animal behavior, and many focused on calves. Research from the University of Guelph provided some insight into lying times of calves through the time of weaning. In one study (Ollivett et al.), lying times were compared for healthy calves and calves that developed respiratory disease over a 4-week period beginning at 10 days of age. Calves spent an average of 20.6 hours each day lying down, that’s 86% of the day. Lying time decreased 4 ± 1 minute each day as the calves grew older. In addition, calves with a fever had lying times that were 44 ± 14 minutes greater than healthy calves. In a second study (Overvest et al.), calf behavior was monitored during three periods: 30 to 39 days of age (before weaning), 40 to 49 days of age (during weaning), and 50 to 56 days of age (after weaning). Calves spent approximately 18 hours a day lying down before weaning, 17 hours during weaning, and 16 hours after weaning. In another report, researchers from Texas A&M (Friend et al.) observed that during heat stress calves housed in hutches increase the amount of time spent lying down to avoid hot air near the top of the hutches. 

A large part of a calf’s daily time budget is spent lying down, therefore the resting surface plays an important role in maintaining calf health. Effort spent to provide adequate resting space with a clean, dry surface and ventilation that removes ammonia near the bedding surface will be rewarded with healthier calves. Guelph researchers recommend that group housing system designs include resting space that enables all calves to lie 75 to 85% of the day. In cold weather, the resting surface should not contribute to heat loss, and deep straw may be used to provide nesting sites that increase insulation. During hot weather, bedding hutches with inorganic material such as gravel or sand may help to keep calves cool because some body heat will be transferred to the bedding. Understanding the amount of time that calves spend lying down should make it obvious that maintaining calf pens is not a “minor” task on the daily list of chores. In addition, attentive calf managers may be able to use changes in lying behavior to identify sick calves early.