The pathway to highly productive cows with good longevity starts with healthy calves and heifers. However, according to the 2007 USDA report almost 8% of heifer calves die before weaning; this represents not only direct economic losses but also losses of future economic benefits and genetic potential. The latter is even more severe assuming a progressive breeding plan since calves normally have a higher genetic value than adult cows. Even when the calf survives the pre-weaning period, serious illnesses and health issues like diarrhea and other digestive disorders can affect future lactation performance. Therefore, the best strategy to produce healthy, high performing cows is to put an emphasis on calf management and heifer rearing and adopt an integrated management system including calving management, colostrum administration, nutrition and veterinary practices.
The power of plants
Because the use of antibiotics as a growth promoter or preventative treatment was banned in several countries years ago, alternative solutions for the support of animal health have to be found and applied.
Historically, the curing and health supportive effects of plants have been used for thousands of years and have been re-discovered in scientific circles over the past decades. Phytogenics are plant-derived substances that can serve as a natural growth promoter. In previous decades, the research of phytogenic additives focused mainly on their use and effectiveness. Hence, more and more questions are being answered in terms of their biological activities. This knowledge is also crucial in newborn calves. In several regions across the world, the application of phytogenics is already well established to improve feed intake and growth performance.
Stressors can disrupt gut performance
In calves, strong feed intake creates the basis for enhanced rumen development and growth performance. Early in life, calves not only have to adapt to the new environment, but also have to cope with several changes in their housing and nutrition. After receiving colostrum for the first days of their lives, their daily milk intake changes usually to milk, waste milk, milk replacer or a mix of those. Further, calves are sensitive to the way milk is supplied to them, putting an emphasis on temperature, timing and hygienic quality. Later, roughage and concentrates are also administered to their diet. Weaning is another crucial stress factor, especially as it is usually accompanied by a change of housing.
These stress factors can lead to an increased incidence of diarrhea and other gastrointestinal disorders. The bioactive compounds of plant-derived substances have been shown to have beneficial effects in maintaining calves’ feed intake, further supporting both digestion and feed utilization.
To have a positive effect on feed intake, palatability is the key. Phytogenic compounds, such as herbs, spices, extracts or even single active compounds exert a range of flavoring properties. Consideration of species-specific preferences in the formulation of a phytogenic additive requires a deep understanding of flavoring properties of each plant-derived substance. There are several types of flavors which can be added to animal diets in order to improve sensory properties of the feed or mask unpleasant flavors.
Plants and their efficacies
Besides palatability, a proper understanding of plants and their bioactive efficacies of both volatile and non-volatile compounds is a prerequisite in the formulation of an effective phytogenic feed additive capable of delivering a positive influence on gut performance. The incredible biodiversity of the plant kingdom provides various active substances to support one or more effects in the organism. Examples of selected essential oils with some major constituents are shown in Table 1.
Table 1. Important constituents of selected essential oils (adapted from Jänicke et al. 2013 and Tisserand and Young 2014).
Spices, herbs, essential oils or extracts have different impacts depending on the chemical structure of the constituents or active compounds. Phenols such as thymol, carvacrol and eugenol (often derived from thyme, oregano and clove) and their methyl ethers have strong antiseptic properties. Carvacrol and thymol seem to demonstrate outstanding antimicrobial properties. Strong antioxidative properties are associated to species of the families of Apiaceae (e.g. caraway and fennel) and Lamiaceae (e.g. rosemary and peppermint).
Furthermore, plant extracts and oils such as clove and rosemary exert anti-inflammatory effects. This matters because both antioxidative potential as well as anti-inflammatory effects are key parameters in gut protection. Other plant compounds improve digestibility by supporting digestive secretions such as bile, mucus and saliva as well as enhancing enzyme activity. In addition to the advantageous effects listed here, further beneficial impacts have also been attributed to phytogenics.
Supporting calves’ gut performance
Gut performance and health have clear importance in growing calves given the benefits of good digestion, high feed efficiency, animal health and welfare. Digestibility and gut protective effects are of particular importance in newborn calves and around dietary changes such as weaning. Effective phytogenics require precisely defined formulations, high quality standards and strict quality control which ensure the right amount of bioactive compounds to improve palatability, thus supporting calves during these critical stages.
During the first weeks of life calves’ diets can be supported with Digestarom® (a specifically formulated phytogenic product designed to support digestion and feed efficiency by combining unique flavoring properties with biologically active properties) in milk or milk replacer when the rumen is still underdeveloped and calves rely on nutrients from milk. Later, when calves start ingesting starter feed or concentrates, respectively, feed intake and the balance in the gastrointestinal tract is recommended to be supported by supplying Digestarom® in the calf concentrates.
Offering milk and starter feed supplemented with a phytogenic feed additive which precisely meets the gustatory and olfactory preferences of calves encourages feed intake and provides a steady amount of bioactive compounds to support the organism by improving digestibility, modulating gut microbiota and reinforcing the antioxidative and anti-inflammatory status (Figure 1). These are key elements in proper rumen development and achieving good growth rates while increasing feed efficiency, resulting in an economic benefit.
Figure 1. Concept for application of Digestarom® in calves.
A recent study including Digestarom® in milk replacer and calf concentrates improved feed intake by 2.1%, increased animals’ average daily weight gain by 8.1% (Figure 2) and improved feed efficiency by 5.6% (Figure 3) compared to the control group. Enhanced performance results along with decreased veterinary treatment costs resulted in an improved economic result.
Figure 2. Effect of Digestarom® supplementation on average daily weight gain of weaning calves.
Figure 3. Effect of Digestarom® supplementation on FCR of weaning calves.
In order to ensure a smooth change around weaning, a constant level of bioactive compounds is recommended to be supplied in milk or milk replacer as well as in concentrate to support calves in the time when they have to increase their concentrate intake as milk supply is declining. Digestarom® can help calves cope with challenges in their first weeks of life by influencing digestibility, gut microbiota modulation and antioxidative and anti-inflammatory processes. Digestarom® also offers the potential to support feed intake in calves by having a palatability-enhancing effect which creates the basis for enhanced rumen development and growth performance—ultimately offering a potentially higher economic result.