Highlights of the Dairy 2007 Survey: Focus on Calves and Heifers
Posted: February 3, 2008
The USDA’s National Animal Health Monitoring System (NAHMS) recently published part one of the results of the Dairy 2007 national survey. This periodic snapshot of current management practices provides insight into current trends and changes over time. The first such survey focused exclusively on calves and heifers and began in 1991. The following discussion highlights some trends over the four survey years (1992, 1996, 2002, and 2007) and details some of the new 2007 data.
Colostrum and the Newborn Calf
Figure 1. Age of calves when separated from their dam, as determined by the USDA:NAHMS dairy surveys from 1992 through 2007.
Figure 1 shows impressive progress in reducing the amount of time calves spend with their dam. Timely removal of calves cuts down on the exposure to bacteria in the maternity area and provides the opportunity for early feeding of colostrum and early assistance to calves distressed by a difficult birth.
Even though calf removal times have shown steady improvement, in the 2007 survey colostrum feeding method appears to have lost ground (Figure 2). The percentage of calves that obtained first colostrum by nursing increased from 30.5 in 2002 to 45.1 in 2007. Research clearly shows that nursing is an unreliable method of feeding colostrum. Up to 40% of calves have insufficient levels of IgG (< 10 g/L) when expected to nurse colostrum. Nursing presents a challenge because we cannot control the time of feeding, the amount fed, or the quality of colostrum. In addition it prolongs the time that these calves are in the maternity pen and exposes them to more pathogens from the pen as well as the dam.
Figure 2. Methods used to feed colostrum to newborn calves, as determined by the USDA:NAHMS dairy surveys from 1992 through 2007.
The amount of colostrum fed to calves during their first 24 hours of life has not changed much since 1991. The Dairy 2007 survey showed 23.3% of farms fed 2 quarts or less, 45.8% of farms fed more than 2, but less than 4 quarts, and 30.9% fed 4 quarts or more. If we look at this same question based on the percentage of calves, more than 80% of the calves received more than 2 quarts of colostrum. The 2007 survey also showed that the time between birth and the first feeding was about 3 hours for farms that removed calves immediately and hand-fed colostrum.
In 2002, 3.9% of farms measured IgG levels in colostrum; 87.7% used a colostrometer and the remaining 12.3% used another method. In 2007 this question was reworded and asked about measuring IgG or estimating the quality of colostrum.
Overall, 13% of farms either measured IgG or otherwise estimated colostrum quality, but there was a strong effect of herd size. Nearly 20% of herds with 100 to 499 cows and 45% of herds with 500 or more cows evaluated colostrum quality compared to just 7.6% of herds with fewer than 100 cows. When asked the method used for evaluating colostrum, 43.7% reported using a colostrometer, 41.6% relied on visual appearance, 9.7%
Figure 3. Types of liquid feed fed to calves as determined by the USDA:NAHMS Dairy 2007 survey. Totals do not add to 100% because more than one answer was allowed.
considered first milking volume, and 5% used another method. While a colostrometer and first milking volume are not perfect indicators of colostrum quality, they are far more reliable than visual appearance. The only things we can reliably tell from looking at colostrum are whether it is bloody or contains large pieces of dirt or manure, and possibly how much fat it contains. Colostrum quality is extremely variable. A recent Penn State survey evaluated 55 colostrum samples from PA farms. The amount of IgG1 in these samples averaged 35 g/L, but ranged from 12 to 74; IgG2 averaged 6 g/L with a range of 3 to 21. The only way to manage this variability is to test colostrum IgG using a reliable method.
The 2007 survey included a description of feeds offered to calves at any time before weaning (more than one answer was possible, so the totals do not add up to 100%). The results of this question are presented in Figure 3. Approximately 60 to 70% of farms fed some milk replacer before weaning. About 30% fed some waste milk and about the same number fed saleable milk.
The 2007 survey also reported the average age at which calves were fed water (15.3 days), starter or other concentrate (8.5 days), and hay or other roughage (24.5 days). This question was also asked in the 1992 survey. The age when water was first offered has decreased by 10.5 days; however, calves will drink water much earlier than it is currently being offered. Starter is being offered about 1 day earlier on average than it was in 1992, and again, there is opportunity for improvement. It is also interesting to note that water was offered a week later than starter. The current recommendation is to provide water and starter within the first 3 days of life. Water intake encourages starter intake, and calves that are eating starter drink more water, so they should be offered together. Hay was offered to calves 1 day later than it was in 1992, but still nearly 5 weeks before weaning. Research proves that hay is not beneficial to calves before weaning. In addition it adds to labor requirements and frequently much of it becomes bedding rather than feed. Average weaning age remained nearly constant at 8.2 weeks, and still represents a significant opportunity for reducing calf rearing costs.
Death losses in heifer calves before weaning decreased a bit to 7.8% of heifers born alive, this is the first time since 1992 that this number has been less than 8%. We may be making improvement on the mortality issues, but it is slow progress. Scours and pneumonia remained the top 2 causes of mortality in preweaned calves. For the first time in this survey, stillbirths (defined as calves born dead and those that died before 48 hours) were reported and accounted for 6.5% of calves born.
Some important improvements in calf care have occurred over the past 15 years, most notably the shortened interval between birth and being removed from the maternity pen and the earlier provision of water to calves. However, areas of opportunity remain. The importance of colostrum to the newborn calf cannot be overstated. Opportunities to improve colostrum management exist at nearly every step: test and feed only high quality; feed by hand, not by nursing, and feed 3 quarts as soon as possible after birth. Finally, look for opportunities to reduce unnecessary expenses. Encourage early starter and water intake, wait until after weaning to feed hay, and wean based on starter intake and calf health, not on calf age.Coleen Jones, Research Associate, and Jud Heinrichs Professor of Dairy and Animal Science