Source: PennState Extension
Ensuring that your calves are achieving a healthy weaning transition is key to their nutritional success as they grow and develop.
Are your calves experiencing a decrease in performance once they are transitioned from milk? Perhaps you are seeing an increase in illnesses, a drop in weight gain or your calves are just having a hard time adjusting to their new feeding system. There could be a number of different factors affecting the performance of your calves. Ensuring that your calves are achieving a healthy weaning transition is key to their nutritional success as they grow and develop. The following are some key elements of the weaning period to take into consideration if you are experiencing setbacks during this critical time.
Whether you are feeding whole milk or a milk replacer, the quantity fed is going to affect your weaning transition. The amounts of milk fed as well as the number of feedings each day will have an impact on how soon your calves begin to consume starter grain. When transitioning calves, remember that there is an inverse relationship between milk consumption and starter intake. More simply, the more milk being consumed, the less grain is being consumed. If your calves are constantly being satisfied with milk feedings, they are less likely to start to nibble at starter that is available to them. Starter grain should be available to calves by day 3 of life. Although most calves will not begin to eat grain at this age, it is important to make it available to encourage consumption.
In a recent Journal of Dairy Science article, a study by Mirzaei et al (2020), focusing on step-down weaning approaches for dairy calves revealed some of the effects of starter intake through various weaning approaches. According to the article, after colostrum feeding, milk allowance and weaning management are the most critical factors determining the growth and health of calves. Although there have been recent recommendations to promote feeding higher volumes of milk per day, there is also a correlation between higher milk allowances and depressed intakes of solid feed which can delay ruminal development, creating a challenging transition for calves weaning off of milk.
Remember that starter intake is key for rumen development. In order for calves to be able to handle the switch from a liquid diet to a solid diet consisting of grains, and eventually forages, their rumens need to be properly developed. In order for adequate development to occur, a calf needs to be consuming at least half of a pound of grain per day for 21 to 28 days to grow a suitable level of rumen papillae. This papillae growth will aid in nutrient absorption in the rumen to be utilized by the growing calf. Without adequate development, a calf’s rumen is not equipped to handle the nutritional change that comes with weaning and will not be able to utilize the nutritional components of their new grain diet. There are numerous varieties of starter feeds available for calves. Regardless of the type, a calf starter should never be dry, dusty, or moldy. A good quality starter will be palatable, smell, and taste appealing to the calf, and should always be fresh and readily available to encourage intake.
A gradual transition from liquid feed takes time. Many farms are limited for space for growing calves and depending on the time of year and influx of calves, some calves may be moved out of their hutches sooner than anticipated. Although this is a common problem for many farms, it is important to give that transitioning calf adequate time to ensure she is ready for her big move. According to the USDA, in 2014 31.1% of farms were weaning their calves at 9 weeks of age or later. This number has grown from the 2007 data that showed only 25.6% were weaning at 9 weeks or later. In 2014, 18% were weaning at 6 weeks 9.2% weaned their calves at 7 weeks, and 7.5% weaned calves at 5 weeks or less. So as you can see, there is great variability in weaning times across the country. While management practices, farm size, and labor availability may be some of the factors affecting weaning age, it is important to remember that the actual transition time to wean a calf from milk should be a gradual process where calves are cut back on the amount of milk they receive each day. The most common example would be with farms feeding milk two times per day then cut back to one feeding for a full week before stopping milk feeding altogether. Whatever your feeding program, it is important to decrease the amount of milk being fed so calves can learn to fill this new void with the starter grain that is available. If space is a limiting factor on your farm, consider decreasing your age of weaning and offering this period of decreased milk availability sooner to see how the calves respond. Earlier weaning times mean more money saved, especially when feeding a milk replacer.
In the study by Mirzaei et al (2020), various step-down weaning processes were researched. All calves on the study were fed 8 L/day of milk from day 3 to day 10. After that, different weaning methods were evaluated. The first group was fed 8 L/day for 4 weeks and then fed 4 L/day for an additional 5 weeks. The second control group received the 8 L/day for 6 weeks and decreased to 4 L/day for an additional 3 weeks. The third group was fed 8 L/day for 8 weeks and only cut back to 4 L/day for an additional week. The last group was fed 8 L/day until they were abruptly weaned at 9 weeks of age. All calves were weaned at 9 weeks and were monitored for an additional 2 weeks. Starter intake for all groups was monitored and average daily gains (ADG) were determined. Throughout the study, it was shown that the earlier the calves were offered less milk, the earlier their starter consumption increased. These calves showed similar ADGs compared to the calves weaned at later ages but were able to avoid any weight loss after weaning like some of the calves on the later weaning groups. It was concluded through the study that the implementation of a step-down procedure earlier (at 4 weeks of calf age) is a better strategy than implementing gradual weaning at a later age to promote solid feed intake and to minimize the loss in body weight (BW) gain.
Another important recommendation is to allow calves time following weaning to remain in their same environment for at least a week for close monitoring. During this time, pay attention to grain intake and overall health of the calf. If calves are eating at least two pounds of grain a day once weaned, they should handle their next transition well. When the decision is made to move calves into a new environment, be sure to limit the number of stressors during this time. Do not make an environment change, a timed vaccination, and a nutritional change all at once. Try to space out the stressors for the calf. If you are grouping calves together, make the environmental change but continue to offer the same diet while the calves become acclimated to their environment and their pen mates. Once a few days have passed, then make the change to their diet. Time vaccinations when calves are least stressed to allow for the vaccination to work properly. Remember through the entire weaning process, a stressed calf can turn into a sick calf very quickly. A stressed calf with an underdeveloped rumen can lead to disasters in your weaning groups. Limiting stress and allowing that calf to slowly adjust to changes can be the difference in the success of your weaning program.
Reference:
Mirzaei, M., Khanaki, H., Kazemi-Bonchenari, M., Khan, M., Khaltabbadi-Farahani, A., Hossein-Yazdi, M., and Ghaffari, M. (2020). Effects of step-down weaning implementation time on growth performance and blood metabolites of dairy calves. Journal of Dairy Science, 103. doi.org/10.3168/jds.2020-18520
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