Westside Enterprises

Trace mineral source can impact feed efficiency, fibre digestibility and carbon footprint

By dr Heinri Spangenberg and dr Noélle Steyn, Westside

The impact of feed efficiency on farm performance is huge and a commonly used performance indicator in beef, swine and poultry. Surprisingly, it is less commonly used by dairy farmers. Increasing feed efficiency means more milk or meat is being produced from the same amount of feed. This will increase the income over feed costs and reduce the amount of greenhouse gasses per kg of milk or meat produced. Improving feed efficiency should be a high priority in any livestock production system. Feed efficiency is defined as the amount of dry matter consumed per kg live body gain, while in dairy cows it can be defined as kg of Energy Corrected Milk (ECM) per kg of dry matter consumed. Feed efficiency in lactating cows can vary from <1.3 to >2.0. There are several factors that have an impact on feed efficiency, such as production level, days in milk and level of rumen acidosis etc., but improving digestibility of feed can have a huge impact on feed efficiency.

The impact of livestock production on global warming is an area of debate and a hot topic around the world. Farmers are globally experiencing increased pressure from consumers to reduce their carbon footprint. Consumer – retailer – processor – farm – feed company and nutritionists are the flow of demand. Soon feed additives will have to follow a Life Cycle Assessment (LCA) to achieve an independent validation of its ability to reduce the animal’s carbon footprint per kg milk or meat. Improved feed efficiency is obviously the way to go to reduce carbon footprint.

Microbes in the rumen are very sensitive to disturbance, in which case a disbalance can occur, referred to as dysbiosis. Dysbiosis of the rumen flora results in poor digestibility of dietary fibre and a significant reduction of dairy cow and ruminant performance in general. Sulphate trace minerals are known to have an antimicrobial effect. The sulphate salts commonly used in dairy feed are highly soluble in the rumen, resulting in high peak concentrations of free metal ions with a negative effect on the rumen microbes. Just think about CuSO4 in a footbath to kill bacteria infecting the hoof. In contrast, the hydroxy forms of trace minerals in IntelliBond (IB) are largely insoluble at a pH of 4 or higher. The rumen pH of dairy cattle is typically between 6 and 6.5 and higher for extensive grazing animals, so hydroxy trace mineral crystals are essentially insoluble within the rumen. In the abomasum, where the pH is usually below 3, the crystals dissociate layer by layer, resulting in a gradual and sustained release of trace mineral ions into the duodenum. As a result, peak concentrations in the rumen always remain low and therefore, these specific trace minerals do not have a negative impact on fibre digestibility.

The effect of sulphate and IB trace mineral supplementation on NDF digestibility was studied extensively with different diets in dairy cows. The peer reviewed studies have proven that replacing sulphate trace minerals with IB hydroxy trace minerals will result in a significant improvement of fibre digestibility and that each one-point difference in NDF digestibility can represent 0.25 to 0.3 kg of daily ECM production. In a trial carried out by Cornell University, milk production was increased in early lactation cows fed IB trace minerals compared to cows fed sulphates. The IB group reached peak production sooner and produced 3.5 litres milk more at the peak of lactation. Dynamics of lactation persistency would indicate that 1 kg of extra milk at peak lactation is equal to 200 kg of milk per lactation. More recent studies also resulted in a significant increase in milk production and an increase in milk fat in cows fed IB trace minerals.

Animals have a thermoneutral zone, in which normal body temperature is maintained and energy expenditure is kept to a minimum. Factors such as temperature, ambient humidity and wind can influence an animal’s capability of staying within this range. When the total heat load on an animal exceeds its capacity for heat dissipation heat stress can be an unwelcome result. A reduction of feed intake and milk production and for that matter ADG in feedlots is a consequence of heat stress. After a while DMI is restored, but not production. Until a few years back the belief was that the extra energy from restored DMI is used by muscle, but in recent years it became evident that it is used to fight inflammation.

Beyond reducing the level of nutrients available for the animal to use, reduced feed intake can therefore harm gut integrity. Less feed intake can lead to leaky gut, which increases circulating bacterial components and can lead to systemic inflammation, inducing a further loss in performance. From a sustainability perspective, leaky gut can potentially increase the environmental impact of production. Thus, from an animal welfare and environmental point of view, heat stress can cause animals to suffer physically and result in a more of the energy consumed being wasted.

Nutritional interventions represent a practical and cost-effective opportunity to reduce the negative effects of heat stress and improve animal productivity. Precision nutrition allows diets to be formulated in a manner that reduces internal metabolic heat generation. Increasing the levels of dietary fat and reducing the amount of protein or fibre is one example of tailoring the formulation to reduce metabolic heat generation. Compared to other feed ingredients, dietary fat generates less heat. In contrast, the fermentation of fibre and excess protein are associated with heat generation. Feed additives that supply antioxidants, osmolytes or gut health should be considered to support animals subjected to heat stress. Selecting trace minerals that are more bioavailable could potentially ameliorate production losses as well.

Feed efficiency is an important driver of farm profitability. It is research proven that IntelliBond hydroxy trace minerals, compared to any other trace mineral source, improves fibre digestibility in ruminant diets with improved performance. The use of IntelliBond Zn, Cu and Mn in dairy cattle was recently validated via an independent, ISO compliant review process to reduce the carbon footprint by up to 2.0% per kilogram (kg) of ECM, while optimizing cow productivity and well-being at very little or no incremental cost to the farm.

Find out more about IntelliBond or contact Dr. Heinri Spangenberg at heinri@westside.co.za