Calves are a vital part of the beef industry, and their development is crucial to their future success.
One of the most important aspects of calf development is their transition from a milk-based diet to solid food. But when do beef calves start eating grass?
This question is essential for farmers and ranchers who want to ensure their calves are healthy and growing properly.
In this article, we will explore the timeline of calf development, including when they start ruminating and when they can begin to digest solid feeds.
We will also discuss the importance of proper nutrition and management during this critical time in a calf’s life.
So, let’s dive in and learn more about when beef calves start eating grass!
When Do Beef Calves Start Eating Grass?
Beef calves typically start to nibble on grass or hay within one to two days of being born. However, their digestive system is not fully developed at this stage, and they are not yet able to digest solid food effectively.
Calves start ruminating to some degree when they are about two weeks old, with their rumen fully developed by 90 days of age. This is when they can begin to digest solid feeds and start to consume grass.
In early weaning systems, calves need to begin eating some grain by two weeks of age to allow enough rumen development to occur before weaning at five or six weeks of age. If we do a good job of managing grain intake, it is possible to wean calves at six weeks, even when milk feeding rates are high.
It is important to remember that deciding to wean calves at a later age or bigger body weight does not remove the rumen development requirement. If calves are drinking a lot of milk, they usually will not eat much grain. Trying to wean calves that have not been eating grain is setting them up for a rough transition.
The rumen of a newborn lacks the microbial population that enables adult cattle to process forage fiber via fermentative digestion. Rumen development proceeds rapidly once solid food consumption begins.
Research suggests that spring-born calves consume significant amounts of native range forage at 45 days of age. Weaning beef calves as early as 45 days of age is early enough to encourage the cows to cycle and rebreed.
Weaning calves this early is used as a “last resort” management strategy when cows are thin prior to the start of the breeding season. Weaning at three to five months of age is too late to cause early cycling; therefore, it doesn’t contribute to the improvement of reproduction.
Weaning calves at 45 to 60 days of age may be a management strategy included in a drought plan. Weaning calves at three to five months of age may also be a viable alternative if forages are scarce in the latter part of the grazing season.
The Timeline Of Calf Development
The development of beef calves begins with fertilization of the oocytes, and mitotic cellular divisions begin to take place. This is the earliest stages of embryogenesis. At 24 hours, the fetus is a 2-celled embryo; on day 1.5 it is 4-celled, and by day 3 it has reached 8 cells as it travels down the oviduct toward the uterus, entering it between days 5-6. Now massive growth begins to occur.
On day 13, the fetus will be about 3 mm in diameter, and by day 18 fetal membranes will be large enough to occupy portions of both uterine horns. During this phase, portions of the developing cells will become the placenta. Maternal recognition of pregnancy will occur, with uterine attachment of the placenta following between days 18 to 22.
Further development begins to take place at this point. By day 20-22, a heartbeat is established in the fetus, and by day 25 limbs are beginning to develop along with the development of organs such as the liver, pancreas, lungs, thyroid, sleep, brain, and kidneys. By the 45th day of gestation, the testicles of the male fetus will begin to develop.
In the female, ovarian development takes place between 50 to 60 days following ovulation. Around day 49, digestive system development begins. While the fetus is continually growing in size throughout gestation, over 75% of its total weight gain and growth will take place in the last trimester of gestation.
As gestation draws to an end, brown fat deposition is completed accounting for 2% of the live birth weight of the calf. In addition, the final development of the lungs is taking place making it a critical time for the health of the unborn calf.
After birth, calves start ruminating to some degree when they are about two weeks old with their rumen fully developed by 90 days of age. This is when they can begin to digest solid feeds and start to consume grass.
The Importance Of Transitioning To Solid Food
Transitioning to solid food is a critical step in the development of a calf’s rumen. Rumen development begins when calves start eating solid feeds that enter the rumen. For dairy calves, that first feed is usually starter grain, which contains starch. The bacteria that colonize the rumen come from the environment and from feeds the calf eats.
As the calf begins to eat more solid feed, that feed determines the type of bacteria that dominate in the rumen. The bacteria that digest starch produce butyrate and propionate. Bacteria that digest fiber produce mostly acetate. Cells in the rumen wall use butyrate for energy and growth.
By giving calves access to starter grain, we encourage the fermentation of starch, which lowers rumen pH and encourages bacteria growth and the production of butyrate. So encouraging grain intake stimulates the growth of rumen papillae, which increases the surface area of the rumen that is available for absorbing the nutrients being produced.
Regardless of when the process starts, it takes 2 to 3 weeks for the bacterial population to grow to a number that can efficiently digest grain. This timing is critically important as we try to manage calves through the stress of weaning.
Weaning beef calves as early as 45 days of age is early enough to encourage rumen development and promote healthy digestion. However, it is important to ensure that calves are consuming enough solid feed before weaning them. Calves need to begin eating some grain by two weeks of age to allow enough rumen development to occur before weaning at five or six weeks of age.
When Do Calves Start Ruminating?
Calves start ruminating to some degree when they are about two weeks old, with their rumen fully developed by 90 days of age. Ruminating is the process by which the calf regurgitates and chews its food, allowing it to be broken down further in the rumen before being swallowed again.
During the first few weeks of life, calves rely solely on milk for their nutrition. However, it is important to start introducing solid feeds early on to allow for proper rumen development. In early weaning systems, calves need to begin eating some grain by two weeks of age to ensure enough rumen development occurs before weaning at five or six weeks of age.
It is important to note that trying to wean calves that have not been eating grain is setting them up for a rough transition. If calves are drinking a lot of milk, they usually will not eat much grain. Therefore, managing grain intake is crucial in ensuring proper rumen development and a smooth transition during weaning.
Once the rumen is fully developed, calves can start to consume grass and other solid feeds. Research suggests that spring-born calves consume significant amounts of native range forage at 45 days of age. Weaning beef calves as early as 45 days of age is early enough to encourage the cows to cycle and rebreed.
When Can Calves Begin To Digest Solid Feeds?
Calves can begin to digest small amounts of solid feeds at around three weeks of age. At this stage, they should have access to concentrates, such as starter grain, which contains starch. The bacteria that colonize the rumen come from the environment and from the feeds the calf eats. As the calf begins to eat more solid feed, that feed determines the type of bacteria that dominate in the rumen.
It takes 2 to 3 weeks for the bacterial population to grow to a number that can efficiently digest grain. Therefore, it is important to introduce any feed changes slowly and gradually so as not to stress or upset the calf’s digestive system. Calves should also have access to dust-free, highly palatable calf starter feeds containing 75 to 80 percent total digestible nutrients (TDN), 15 to 20 percent crude protein, and adequate minerals and vitamins.
It is essential to encourage grain intake as this stimulates the growth of rumen papillae, which increases the surface area of the rumen that is available for absorbing the nutrients being produced. This is critical in managing calves through the stress of weaning.
The Benefits Of Grass For Beef Calves
Grass is the natural dietary staple for beef cattle, providing the necessary nutrition for healthy and strong bodies. When beef calves start consuming grass, they receive a variety of benefits that contribute to their overall health and well-being.
Grass-fed diets are ideal for animal health, as they contain higher levels of beta-carotene, vitamin C and E, and omega-3 fatty acids. These fatty acids encourage a healthy vascular and nervous system, reducing the risk of chronic diseases such as cancer. Compared to grain-fed diets, grass-fed diets are also lower in fat and calories, making them a healthier option for beef calves.
Additionally, grazing on pastures encourages constant movement for beef calves, leading to leaner and stronger bodies. The natural diet of grass provides the necessary nutrition to support healthy growth and development. As the rumen of a newborn calf lacks the microbial population that enables adult cattle to process forage fiber via fermentative digestion, consuming grass helps develop their rumen rapidly.
Proper Nutrition And Management During Calf Development
Proper nutrition and management during calf development are crucial for the growth and overall health of beef calves. The three most essential nutrients for calf growth and development are water, energy, and protein. Adequate nutrition of the growing calf is essential in order for the calf to grow frame, gain body weight, and achieve an acceptable final weight. Calves need to be provided with as much fresh, clean water as they want.
It is important to note that the use of hormonal implants as a management practice for suckling calves may increase weaning weights by 3%–5%. However, heifers kept for breeding should not be implanted if < 45 days old, and bulls should never be implanted. Disease can harm a calf's growth rate and create chronic problems that limit the calf from reaching full genetic potential. Therefore, it is necessary to measure both survival and growth rates to measure calf-raising success.
Developing a strong immune system in beef calves begins with key management factors that must be acted upon prior to calving. Passive transfer of colostral (first milk) immunoglobulins is vital to short-term health as well as lifetime immune function. Calves that do not have adequate blood concentrations of immunoglobulins from the dam’s colostrum within 24 hours after birth are more likely to be treated for Bovine Respiratory Disease during the feedlot phase.
In early weaning systems, calves need to begin eating some grain by two weeks of age to allow enough rumen development to occur before weaning at five or six weeks of age. It is important to manage grain intake properly so that it is possible to wean calves at six weeks, even when milk feeding rates are high.
Once calves start ruminating at around two weeks old, their rumen will fully develop by 90 days of age. This is when they can begin to digest solid feeds and start to consume grass. It is important to remember that trying to wean calves that have not been eating grain is setting them up for a rough transition.
