NEW ZEALAND SOILS ARE LOW IN SELENIUM

Selenium is an essential trace element for ruminants and required for growth, fertility and the prevention of mastitis and calf scours. However, selenium deficiency is prevalent in soils around the country. This presents an issue every farm manager would benefit from understanding better. A new generation of organic selenium supplementation (called Excential Selenium 4000) will be introduced into New Zealand this year. It’s an exciting development, providing a significant improvement to previous options for selenium supplementation on the farm. But first we need to understand the relevance and impact of selenium deficiency.

WHY IS SELENIUM IMPORTANT?

Specific enzymes (selenoproteins) require the incorporation of selenium to ensure their activity in the animal. These enzymes reduce the presence of oxide radicals (produced during normal metabolic activity and elevated during stressful periods) that cause cell damage and subsequent malfunction of tissues. Protection against these harmful by-products is especially important in high-energy demanding cells such as heart, muscle and mammary gland cells.

Unfortunately, there is often a selenium deficiency in animals due to limited uptake from the diet. These deficiencies can be pronounced in ruminants grazing on pastures grown on selenium-deficient soils, such as here in NZ. Resulting challenges may include suboptimal milk production and fertility, mastitis and premature, weak calves. In places with severe selenium deficiency calves have poor growth rates, difficulties standing, and sudden deaths can occur. To prevent this, it is important to provide additional selenium via the diet and assess regularly the selenium status of the herd by analysing blood and milk.

SELENIUM DEFICIENCY – A NUTRITIONAL SOLUTION

Selenium can be added to the diet in either inorganic or organic forms. The advantage of using organic selenium over inorganic sources (e.g. sodium selenite or selenate) is its ability to be incorporated directly into animal proteins. This incorporated selenium (in the form of L-Selenomethionine) acts as a storage depot of selenium inside the animal. L-Selenomethionine is the only selenium compound that can be directly, without conversion, built into animal structural proteins (i.e. muscle and liver). This ensures optimal selenium supply, even during stressful periods (e.g. calving, lactation, heat) when selenium intake is required most by the animal.

It is tempting, given the limited research around goat nutrition to assume a goat’s nutritional requirements fit somewhere between that of sheep and cattle. This assumption would be a mistake. When it comes to mineral nutrition goats have very different requirements.

Based on a goat’s production level when related to body weight and feed intake, these small ruminants are probably better compared to the ruminant equivalent of an F1 racing car. Just as you wouldn’t run a high performance car on low octane fuel, you shouldn’t feed your goat the same way as you would cattle and sheep. Goats have different and very specific nutritional requirements. If these requirements are not met, the animal will not perform to its full potential, and worse still will be subject to a higher level of disease.

The interesting thing about goats is that their requirement is both higher and lower depending on the element in question. While their milk is in many ways more nutritious than that of a dairy cow, nature has at the same time designed the animal to survive under very different conditions, and on a very different diet from that of a cow.

SO WHAT ARE THE MINERAL REQUIREMENTS OF DAIRY GOATS?

Lets start with one of the key macro elements, phosphorous. Goats typically have a lower requirement for phosphorous to that of dairy cattle. They seem to be better at recycling it and while they have higher levels in their saliva, losses during rumination are lower than that of a cow.

In contrast calcium requirements are quite high and should be set at least twice that of phosphorous in the diet.

Salmonella link to coarse grade and palleted Magnesium Oxide in Feeds
Over the past few weeks, a number of vets have been reporting Salmonella outbreaks on dairy farms. Our investigations on some of these farms indicate that these outbreaks seem to correlate to use of pelleted Magnesium Oxide being fed in palm kernel based feeds. Although one of the farmers we interviewed, reported some salmonella before feeding the PKE containing the coarsely ground magnesium oxide, he reported that after introducing the feed the disease took off. On discussions with some in the feed industry it would seem that coarsely ground magnesium supplements may have been widely used throughout the feed mill industry over the past 2 seasons. This magnesium is a little different to that used in the past and the pelleted magnesium associated with the outbreaks of salmonella reported in Taranaki. Prior to the last two seasons this coarsely ground form of magnesium oxide was formerly only sold into the fertiliser market and has large particle sizing, ranging from 2mm – 5mm. We believe the same risk factors are involved as those reported in the Taranaki outbreak of 2011 at that time associated to a prilled magnesium oxide product used in those feeds.

A case controlled study was performed in 2011 – 2012 to identify herd-level risk factors for acute Salmonellosis. It is our belief that the most recent outbreak has many of the same issues in common with the earlier outbreak. This summary, identified a number of risk factors that contributed to this sudden outbreak of the infection across a large number of herds, most particularly highlighted was the strong connection between feeding granulated magnesium supplements and prevalence of the disease.

click here to read study

CONTRIBUTING FACTORS IDENTIFIED IN THIS REPORT WERE AS FOLLOWS:

1) Continuous feed troughs – consumption of supplementary feed from shared troughs varies amongst individual cows where dominant cows will consume more than their allotted daily feed allowance, with submissive cows consuming less. Fluctuations in feed intake could affect the rumen microflora balance, allowing salmonella to multiply and cause infection. Reduce risk by using individual troughs.

Innovation through customisation

WHAT IS CUSTOMIZER?

Customizer is an innovative, powerful computer program from Agvance that enables vets and animal nutritionists to formulate custom mineral and vitamin blends and premixes, specific to a customer’s herd requirements. In the past, blood and liver biopsy results have been supplied to farmers with simple recommendations to supplement the elements found deficient, without any professional advice on what type of element or which product would be most suitable. Customizer takes this guesswork out of animal nutrition by allowing qualified people to quickly and easily formulate comprehensive nutrient formulations specific to any situation. Reports are also generated giving detailed information on each element used so that the farmer knows why each mineral is being recommended and how it will benefit their animals.

Once a blend is confirmed and been approved by all parties, each formulation is blended and bagged. Bags are well labelled indicating ingredients, daily dose rate and other relevant information.

FACTS & BENEFITS ABOUT USING CUSTOMIZER:

1 Utilize expertise – only qualified vets or animal nutritionists have access to the program and are able to formulate blends
2 Custom blends – target the specific deficiencies that may be affecting the health of a herd
3 Premixes – a feed module within the program that accurately calculates mineral requirements for a transition cow
4 Accurate reporting – keeps accurate records so that you can track changes from season to season and make any necessary changes
5 Easy and quick to use
6 Total flexibility – wide range of minerals, vitamins & additives to choose from
7 Highly Soluble blends – easy to administer through water, feeds & drenches
8 Access to a library of information on Customizer itself

Calf rearing good practice ensures healthy, happy calves!
Approximately 1.5 million calves are reared in New Zealand each year – 1 million being dairy heifers that will become the future herd replacements. How these calves are raised will affect how they grow and at what weight they enter the herd. It is essential to give such calves a great start to life so as to ensure a long productive, healthy milking life. Heifers that reach target weights make successful milking cows and raising them well starts from the day they are born.

COLOSTRUM

Within the first 24 hours of being born, all calves, including bobbies must receive adequate fresh colostrum or a colostrum substitute and this should continue for at least the first 4 days of life because it will protect against disease by fighting infections within the gut. The calf should drink at least 2 litres of fresh gold colostrum during the first 6 hours of life, and then again at 12 hours to get protective antibodies known as immunoglobulins as they are born with poorly developed immune systems. This process is most effective in the first 24 hours after birth and is known as ‘passive transfer.’ Failure to do this, known as Failure of Passive Transfer (FPT) to absorb enough immunoglobulins in these first critical 24 hours, can make a calf susceptible to disease, death and long term reductions in animal productivity. Past studies have found that 10 – 40% of calves are deficient in colostrum which can result in higher morbidity rates and slower growth rates through to 14 weeks of age.

REASONS FOR FPT

FPT is fairly common with NZ studies indicating a 33% prevalence at various intervals during the spring calving period. A number of reasons why calves get FPT are the following: a) the colostrum has inadequate immunoglobulin levels, b) feeding insufficient volumes of colostrum, c) feeding takes place too late after birth and d) bacteria especially Coliforms contaminate the colostrum at harvest, during storage or at feeding.

TESTING & PREVENTING FPT

To combat FPT, it is imperative that you test your calves to make sure that they are getting enough high quality colostrum within the first 24 hours of life. There are a number of ways to measure and prevent FPT:

Article by Robin Boom. One problem farmers face today in relation to fertilisers is just whose advice to follow, since opinions between scientists, independent consultants, farm advisers and different fertiliser company reps is so wide and varied, and when it comes to the application of boron we have a classic example.
I personally believe the non-application of boron on many farms is costing farmers dearly in the areas of stock health and poor pasture production, particularly from clovers. Although there is debate over the primary function of boron in plants, it is known that boron deficiency reduces the ability of root cells to absorb phosphorus, chlorine and rubidium (used to mimic potassium). This will result in stunted clovers, not only above the soil, but also below as far as the root mass is concerned, thus reducing the plants’ ability to exploit the soil.

Responses to boron become most marked when all the other elements are in good supply. Farms which have regularly received good applications of lime and potassic super, yet on which pasture growth is not really firing, could well benefit from boron. A pot trial at Ruakura showed production responses to boron on a boron deficient soil near Taupo in red clover of up to 107% increase, 74% in lucerne and 43% increase in white clover (NZ Journal of Agricultural Research 1983, p. 197-203).

Boron has also been associated with calcium deficiency in plants and animals. Boron appears to be a catalyst for the absorption and transport of calcium. When cows go down with milk fever, Calcium Boroglucanate (calcium, boron and glucose) is often used as a remedy, and this contains 4% Boric Acid (soluble boron). On one of the Caribbean islands, the high incidence of arthritis was attributed to a very low boron status in the soil. Interestingly enough, New Zealanders also have one of the highest incidences of arthritis in the world. In apple trees, bitter pit, which is caused by a low calcium level, has been corrected through boron applications. Low calcium levels in pasture plants can sometimes be attributed to the low levels of boron, even though the calcium level is good in the soil.

Boron deficiency has also been linked to poor seed and flower formation in grasses and clovers. In another pot trial at Ruakura in 1983, the affect of boron on seed production from red and white clover cultivars and lucerne was tested on a known boron deficient soil. The results were that seed production was multiplied many times with the addition of boron. In red clovers and lucerne, this was caused by a big increase in flower numbers, whereas for white clovers the increase was in the number of seeds per flower (NZ Journal of Experimental Agriculture 1983). This increase in seed production can be very significant for permanent pasture where a lot of natural reseeding takes place.