Calf Growth and Weight Gain
Economically important in both the short and long run
Calf health and growth rate can have a large impact on a dairy operation’s profitability. Good calf health and strong pre-weaning growth can potentially boost milk production in the first lactation. In a study from Cornell University, Van Amburgh et al. (2009) showed that early life events appear to have long-term effects on performance.
Meta-analyses (Soberon and Van Amburgh, 2013; Gelsinger et al. 2017) determined that for every 100 g of additional pre-weaning daily weight gain from milk and starter could result in approximately 136 to155 kg of additional milk yield during the animal's first lactation. This relates to hyperplasia of mammary tissues of calves receiving a higher plane of nutrition during the early suckling phase (Soberon and Van Amburgh, 2017).
A well-planned breeding program should provide replacement heifers with greater genetic potential for milk production than previous generations. Increased number of replacements allows for greater culling options or may provide an additional revenue stream to the farm. Calves that maximize growth rate can only do so when they are healthy. As such if calf growth is slow, producer should look at potential contributions to this problem.
The first parameter to consider is mortality. A reduction in the number of calves flowing through the system decreases the herd replacement opportunities of the future. Calf maladies not only effect calf growth but can also reduce production capacity when cows enter the milking string.
According to the Dairy Heifer Raiser overview from the USDA (2012), of calves born alive, mortality in pre-weaning heifers was 4.2%. This is consistent with other international surveys that place average preweaning mortalities between 5 to 8%, however, calf mortality in some countries ranges up to 20% (Mee, 2013).
The biggest cause of pre-weaning mortality are digestive disorders and respiratory problems, accounting for 56% and 22% of losses respectively (USDA 2012). Diarrhea incidences are most prominent in the weeks following calving, whereas respiratory diseases emerge after a few weeks and continue post weaning (Fig. 5, Svensson et al. 2003, 2006). Calf disease incidences and losses before weaning not only have a short-term economic impact, but they also influence the future genetic and earning potential of the production unit. Trilk and Münch (2010) estimated that even one pre-weaning disease incidence can reduce lifetime production by 10% and escalating with subsequent disease (Fig. 6).
First calving age
Increased calf growth rate reduces the cost of raising replacements. Standard goals include having Holsteins calve at 24 months of age and Jerseys at 21 or 22 months. Studies have shown that calving at ages early than these often end in reduced lifetime milk production.
|Jersey||21 to 22 months|
A closer look at that data also shows that subsequent milk production is much more variable than from cows that calve at 2 years of age. This variability is no doubt do to the frame size and weight at calving has an effect of dry matter intake and subsequent production. If calves are bred before they reach appropriate size, they will likely have smaller frame size as adults. Reaching breeding size sooner reduces the “maintenance” cost for the period between birth and first calving.
Muscle and development
Although dairy breeds certainly develop the amount of muscle associated with beef breeds, they do have a very real need for muscle. The amount of muscle an animal can produce and the efficiency of putting down that muscle occurs when animals are young. Good early growth means cows can develop more muscle. This is important because when cows go through negative energy balance and lack glucose, they can use skeletal muscle proteins (amino acids) as a source of carbons to make glucose through gluconeogenesis. Cows never fully replace this muscle and during subsequent lactations have a smaller “pool” of muscle to use in the production of glucose.
What to feed calves to gain weight
There are multiple feeding and rearing programs and different plans will fit better or worse within each unique dairy operation. This article will not try to cover each scheme, but rather focus on factors which are important for all operations.
Consumption of quality colostrum
Calves are born without the necessary antibodies needed to help protect them from illness. Colostrum contains these needed proteins which are produced by cells of the immune system to help recognize and neutralize pathogens, including bacteria and viruses. During the first day of a calf’s life these antibodies, which are also known as immunoglobulins (Ig), can be absorbed and subsequently utilized.
Colostrum should be consumed as quickly as possible after birth as the gut will “close” and absorption will no longer be possible. Calves should be fed 10% of body weight within the first 6 hours of life for optimal Ig absorption. It is important the quality of colostrum is also maintained. Generally speaking, colostrum quality is better from older cows than younger cows.
Maternity or calving pens
General recommendations are for pens 3.5 to 4 m X 3.5 to 4m in size. They should have a deep bedding of straw or sawdust. Hygiene and comfort are important. Cows prefer an isolated location if possible. Getting the calf dry and ready to receive colostrum are important parts of the calving process.
Many producers prefer to feed calves colostrum rather than letting them naturally nurse. If one does allow nursing, make sure that the teat is clean.
Calf milk replacers
There are a multitude of calf milk replacers available with a wide variety of ingredient qualities and compositions. Regardless of formulation, it is important that they provide the protein, energy, along with vitamins and minerals, to support rapid growth of the young calf.
Depending upon jurisdiction, antibiotics and coccidiostats may or may not be included in the milk replacer. Alternatively, producers can use acidified milk products and phytogenic compounds e.g. essential oils for cattle that have also been demonstrated to reduce threats from dietary pathogens and support calf health and growth.
These types of products can be particularly important when the calf reaches a week to 10 days of age. At this time the immunity received from the colostrum may not have been fully supplanted by the calves own antibody production. In addition, at this age calves begin to eat dry feeds (calf starters) and scours are common. Organic acids and phytogenic compounds can reduce the severity and duration of these scours (typically Escherichia coli related.)
Calf Starter (grain)
It is important for calves to transition from a milk diet to a solid diet. Consumption of calf starters also stimulates the development of the rumen. Generally, it is better to limit the amount of forage presented to calves during the first two months.
Calf starter will actually stimulate rumen development better and contain more energy to stimulate growth. As such, we want to encourage starter intake. Molasses is often used to encourage feed intake. Studies have shown that molasses should be limited to 5% of the diet. Molasses can potentially lead to greater cleaning requirements or increased fly problems.
Using a flavoring product (as with essential oils) can encourage calves to make the move from a milk based to a grain-based diet. As we transition calves from a milk to a grain diet, we must also be cognizant of the potential risk of mycotoxins in cattle feed to an animal that is already under stress.
Phytogenic feed additives
Phytogenic compounds with antimicrobial, anti-inflammatory and anti-oxidant activities can be helpful in supporting calf growth. In many areas of the world, antibiotic use has seen increased restrictions. Phytogenic products represent one technology that can help maintain good calf growth.
It is sometimes difficult to know if calves are healthy because they eat more and have a better diet, or if they eat more because they are healthier. In the end it may not matter as we strive for both from the beginning.
Faster growing calves not only allow for transition to less expensive diet and potentially reduce days to first breeding, but are also better producing cows once they enter the lactating herd. Better growing calves not only provide dividends through lower medication and feed costs, but also add to your bottom line as adult cattle.