Fibre is important in all animal feeds, however, for ruminants it is essential. These animals have evolved a symbiosis with microbial populations which can release energy from plant material, which animal cannot do via their own enzymes.
As grazing animals, ruminants require a constant supply of forage to enable rumen function. Indeed, without forage, either from pasture, hay or silage, the animal is under major distress and will resort to consume all manner of materials to fill the rumen. Although compound feed cannot entirely replace the role of forage, rumen diets are designed to complement nutrient supply in ruminants. Fibre in non-forage feeds can come from many sources, but most are by-products from other industries, especially from human food and oil sources.
Quality
Quality is the major focus for all feedstuffs. Using PKE as a fibre source to balance forage intake means that it has to be managed, either by sourcing from reputable producers (fresh batches which have been properly processed and stored, to prevent fungal and other contamination) or by applying technical ingredients to ensure any risks are minimised.
Palm kernel expeller meal in animal feeds
Palm kernel is a by-product of the palm oil extraction industry, based mainly in tropical countries. The degree of care in its production varies widely – from backyard operations, with the by-product left outside on the ground, to modern, enclosed steel processing plants. This makes it variable in energy and nutrient quality. The amount of oil remaining differs greatly, depending on how many times the palm nut is pressed and whether a solvent has been applied to the residue for final oil removal. If the high fat by-product is not kept in controlled, cool, dry conditions, this can cause rancidity which reduces palatability. Indeed, 40% feed refusals have been reported when 6 kg/h/d is offered to cows, although 3 kg/h/d was deemed acceptable (Dias et al. 2008). It contains good levels of fibre (as NDF), making it a useful feedstuff for ruminants, and, if good quality, can be used in times where pasture access is limited.
The average nutritional profile range of PKE (87-95% dry matter), 13-19% crude protein, 11-27% crude fibre, 0.5-12% oil, and 6-11 MJ/kg energy. Its NDF ranges between 50-75%, but its digestibility can be variable. However, when feeding 30% in the total diet, milk yield has been shown to significantly drop (from 15.3 to 14.3 kg/h/d), rumen pH increased for longer during the day and NDF digestibility declined from 0.022 to 0.19 units per hour, compared to those fed 20% PKE (van Wynaard and Meese, 2017). Protein from PKE is more degradable in the rumen, which, coupled with its average levels, means it can elevate levels in the rumen, increasing N excretion in urine. Care should be taken that the complete diet does not exceed 16% protein.
Minerals (B, Mg, P, Cr, Mn, Fe, Ni, Cu and Zn) may exceed the maximum recommended levels for cattle (Thompson-Morrison et al., 2022). It can contain high levels of Fe from processing and transport (range 0.5-2.4 g/kg), and other heavy metals and toxins can contaminate PKE through this exposure. High levels of Cu, which is used as a cheap pesticide on palm trees, can be evident, with a range of 22-36 mg/kg being reported. In addition, Mn was high, ranging between 0.3-0.5 g/kg as was Zn (44-59 mg/kg). Concentrations of Mg, Al, P and Fe in PKE can exceed the MTL for cattle, while S, K and Cu have been reported to be within 90% of MTL.
In addition to heavy metals and other contaminants, PKE is often associated with mycotoxicosis in cattle, which has been fatal on commercial farms. As a result, there are limits of the amount that can be fed per day, which has been set at 3 kg/h/d in New Zealand. Hence, it is prudent to include a broad-spectrum mycotoxin binder in PKE prior to feeding.
The variation in NDF and other nutrient digestibility may be addressed by the addition of feed enzymes. This has not been studied extensively, but early work suggested their inclusion can increase fibre digestion, leading to increased milk yield and quality. Given than high levels of PKE can reduce yields and affect fat deposition in milk, using feed enzymes and toxin binders offer greater security for the farmer in terms of being able to use PKE when pasture is limited with less risk of performance or health being affected.
Hence, the appropriate supply, use, inclusion level and the application of technical ingredients is important for getting the best out of PKE for ruminants.
Talk to your local Reid’s Dairy Specialist today about the benefits of our mash and the products we can offer to suit your requirements on 1300 REID FEED or enquire here >
Author
Dr Lucy Waldron
Head of Nutrition and Technical Services
