Deciding to use right feed additive in ruminant feeding became crucial because profit margins are narrow and environmental pollution is aggresively increasing in today’s world. Using prompt feed additive at the right time will reduce the work load of technical staff about herd health.
Milk and meat yield efficiency is increased over the years due to genetic improvement and enhanced knowledge of ruminant nutrition. This situation brought some challenges for ruminant nutritionists. First and the most important challenge is to manage balanced ruminal degradation because nutritional approaches has to be changed with increased productivity. Feed additives are briefly explained as “non-essential ingredients that serve to improve yield and/or health of the animal” but they became “essential” to achieve high yields without facing digestive & metabolic disorders. To sum up this dilemma; one can be stated that digestive system & feed materials are nearly same compared to past but feed efficiency increased significantly with genetic selections. This mini-review is written to give short information about some feed additives used in ruminant nutrition.
Vitamin market is facing unordinary days for few months. Reason for this volatility is China’s strict environmental restrictions and a recent force majeure case in an essential vitamin intermediate production plant. In addition to increased grain prices, these advances put some extra effort to ruminant nutritionists’ shoulders when formulating profitable and productive feeds nowadays. As it is clearly known, pure and simple formula for the profitable production is feeding and (therefore keeping) animals healthy. The term “vitamins” was originated from the combination of “vital” and “amine”. Vitamins are considered as well-known nutritional nutrients for animals, but do we have enough information about vitamin requirements and their metabolic effects for today’s high yielding animals? Vitamin nutrition remains a challenging and dynamic field for ruminant nutritionists. Different species require different certain levels of vitamins according their yield type, physiological period, stress stimuli, environmental factors etc. Minimum (or sub-optimum) requirements of the vitamins are determined by the trials made in the past, but we see that real requirements of the vitamins for optimum health and productivity are not the same as requirement tables described by the main references. Optimum Vitamin Nutrition- OVN™ is a concept developed by the leading company of the sector- Royal DSM, describes the optimum vitamin requirements of different animal species for the industrial animal production with optimum yield & health parameters. Figure-1 summarizes this concept clearly.
All of the vitamins (in certain levels) are essential components for the ruminants’ health & productivity. As shown in the Figure-1, suggested vitamin requirements as a result of the dose/response trials made on are providing sufficient vitamin levels only for preventing deficiency symptoms which is not meaning the optimum health & production status. In practice, vitamin deficiency symptoms are generally masked under the metabolic syndromes that often end up with increased production costs. Most efficient and the simplest way to increase profitability in the farms is keeping the herd healthy. It is experienced many times by the professionals, preventing sicknesses is always cheaper compared to treatment costs. In parallel to increased cost of production, some of the vitamins came into prominence because of their metabolic affects that is related with high herd profitability. Β-carotene is known as the “fertility vitamin” by the professionals because of its contributions to the reproductive performance. Biotin is a vitamin which is essential for the healthy hoofs, decreased lameness scores & high milk yields. Higher vitamin E inclusions to diet decreases the mastitis cases, therefore lowers the costs for udder health. Apart from that, all vitamins play unique and complex roles in the metabolism, and it is not a proper approach to give more attention to certain vitamins. There are many articles shows and investigates the vitamins’ simultaneous role for the ruminants, so it will not be explained in detail in this article.
A RADICAL INNOVATION- EXOGENOUS AMYLASE ADDITION TO RUMINANT DIETS
There are many factors affecting total tract starch degradability and digestibility including granule size of starch, corn structure and the protein matrix of the grain source. Main proportion of corn starch that is fermented in the rumen, ends up with energy supply can vary substantially – up to between 50-95% depending on: variety, maturity & vitreousness.
Starch will flow into the small intestine if it is not ruminally digested; endogenous enzymes hydrolyse this compound in there. Although an increased intestinal starch flow can increase the absorption of glucose, an important precursor of lactose for high producing dairy cows, the capacity of the small intestine to digest large quantities of starch is limited. In practice, loose feaces and wasted starch can be the case if it goes beyond duedonum which decreases the F:G ratio and potential milk yield. The effect of poor starch digestibility on milk yield was demonstrated clearly in a study; each 1% reduction in faeces waste starch = 0.5kg improvement in milk yield. A simple calculation shows the actual additional cost of these losses: in a dairy herd of 1000 cows with a daily intake of 5.5 kg corn starch at a digestibility of 95%, the cows excrete the equivalent of 40 tons of corn grain in a 100-day period. These calculations highlight the important additional costs for dairy farmers face with starch waste. One can be achieved to increase milk production per dairy cow with the same amount of feed with a better digestibility.
Improving starch digestibility and readily available energy concentration in the rumen has the potential to enhance efficient milk production, and as a result, profitability. Exogenous amylase plays a significant role in mentioned approach. One particular amylase- Ronozyme Rumistar™ works in the rumen by increasing the starch hydrolysation into oligosaccharides. These oligo-saccharides provide required energy for the activity of bacteria that degrades fiber, which resulting with improved total microbial activity in the rumen. This process ends up with increased total digestibility of the dietary corn. It is called “cross-feeding” means; converting the starch into oligosaccharides that provides substrate for the cellulolytic microorganisms. With mentioned metabolism, exogenous amylase usage makes significant contribution to fiber digestion in the rumen in addition to enhanced starch digestibility. Another advantage of this “cross-feeding” is that the starch is hydrolised into oligosaccharides and not into propionic acid or lactic acid which means the pH of the rumen is kept stable when increasing ruminal starch digestibility. Over the last 12 months, 16 different farm trials conducted to evaluate the effects of this enzyme on nearly 9,000 cows across. The results observed an average response of 1.4kg more milk production and in nine out of 11 farms the digestibility of dietary starch was also improved which is tested by measuring starch faeces with a digestive sieve. This strategy shows high return of investment, the potential of utilizing the possibly wasted nutrients by enhancing ruminal ecosystem and spending less money to produce feaces.
BACK TO THE ROOTS! USING ESSENTIAL OIL COMPOUNDS IN DIETS FOR THE PROFIT AND THE SUSTAINABLE EARTH!
Essential oils obtained from plants have been used for medical purposes during history of humanity. Essence, aroma, antiseptic & preservative characteristic of these compounds arouse curiosity for decades. Using essential oils and plants for medical purposes extends over to 2600 B.C. and to Mesopotamia. Number of studies based on natural essential oil compound mixtures’ effects on ruminant nutrition is still relatively limited but study number in this area is increasing day by day. This area of study seems to remain as hot topic in our daily lives because it is known that 250.000 to 500.000 plant species exist.
METABOLIC EFFECTS OF ESSENTIAL OILS
Using antibiotic growth promotors and ionophores as feed additives is banned in EU and Turkey for years. Essential oils as feed additives are generally used as natural solution in mono-gastric nutrition due to their antibiotic properties which are proven to have some antibiotic effects to certain pathogens with scientific trials.
Numerous microorganisms exist in the rumen. Because their fermentation end products are different, they can be classified to be responsible from Production/degradation of different metabolites. For example, cellulolytic and amylolytic bacteria which degrade carbohydrates produce different volatile fatty acids and proteolytic microorganisms are responsible of ammonia production in the rumen. As well-known, protein digestion metabolism of ruminants is significantly different compared to mono-gastric animals. Nitrogen containing components are generally degraded to the ammonia in the rumen, a portion is used in the rumen and excessive ammonia is taken up to liver to be detoxified. Ammonia is converted to urea which is less toxic for the metabolism. Some part of the urea is excreted via kidneys whereas some part of the urea is brought to the rumen by saliva to represent N source for rumen bacteria. This phenomenon is also known as “rumino-hepatic N cycle” contains some disadvantages. Because whether the consumed protein source contains “the limiting” amino acids or not, all N sources degraded to the ammonia. Essential oil compounds become a part of the metabolism (at the deamination step) by limiting the ammonia producing bacteria. Trails conducted on in vitro conditions shows that hyper ammonia producing bacteria are sensitive to some essential oil compounds. These bacteria represent very small part of total rumen ecosystem but they are responsible from 50% production of total ammonia produced.
Recently, some concerns have been arisen due to industrial animal production’s greenhouse contribution and increased environmental pollution. It is well known that significant portion of greenhouse gas emissions is coming from industrial ruminant production. Methane gas produced in rumen consists some energy and eructating methane causes decreased feed efficiency. Because that energy potential produced in rumen is emitted to atmosphere. Ruminant nutritionists aim to suppress methane emission that is produced and emitted by the ruminants, by that way environmental pollution may be partially decreased and feed raw materials may be utilized efficiently. There are trial results that shows the essential oils’ potential to decrease methane emission caused by ruminants. In vitro trials also show that some essential oils have suppressive effects on methane producing bacteria.
Non-structural & readily fermentable carbohydrates are rapidly degraded and different portions of VFA’s are produced by bacteria located in the rumen. Rumen pH starts to decrease and total VFA charge begins to increase after excessive dietary non-structural carbohydrate intake. Acute acidosis is rarely seen on professional farms and they generally stem from workers’ mistakes. However subacute rumen acidosis is seen often on the field. Ruminant nutritionists are challenged to design risky rations due to reduced feed intakes in fresh period and increased milk yields at the same time. In the mentioned period, subacute rumen acidosis (SARA) starts to occur and prolonged SARA cases are resulted with hoof health impairment. Degeneration of hooves causes a sequence of metabolic syndromes and both yield and reproductive performance are negatively affected. The most important and the most efficient way to prevent SARA is managing a balanced ration intake. After managing the ration, next step is to provide some rumen buffer products with diet. The main effect of the rumen buffers can be thought as partially rebounding decreased rumen pH. But some of the essential oils seem to have suppressive effect on certain amylolytic bacteria such as Ruminobacter amylophilus that slows the ruminal degradation rate of the starch. By that way, rapid degradation of the starch and dramatic VFA accumulation can be precluded and because of that fibre degradation is enhanced. Because fibrolytic bacteria are very sensitive to low ruminal pH values. Increased milk fat yield is accompanied with improved ruminal fiber digestion. Also essential oils promote bacteria that utilise lactic acid and convert it the glucose precursor propionate, so reducing the acid loading on the rumen and therefore improving rumen health and increasing energy supply to the cow for meat or milk production. There are many trials that shows adding essential oil mixture compound that are specially designed for ruminants increases fat corrected milk yield, balances rumen environment and improves feed efficiency.
Deciding to use right feed additive in ruminant feeding became crucial because profit margins are narrow and environmental pollution is aggresively increasing in today’s world. Using prompt feed additive at the right time will reduce the work load of technical staff about herd health. Inclusion of optimum vitamin levels to feeds improves health status and addition of essential oils and novel feed enzymes is critical for achieving the maximum profitability and optimum rumen health.