Dr Gerald Shurson, professor, the Department of Animal Science at the University of Minnesota, led the review, the purpose of which was to provide a holistic assessment of the benefits and limitations of existing chemical analysis methods and measures used to evaluate feed ingredients for pigs.
Traditional proximate analysis measures - moisture, crude protein, crude fat, crude fiber, and ash - have little value for estimating the actual nutritional and economic value of feed ingredients fed to swine, yet they continue to be commonly used in research studies, feed label regulations, and commodity-trading contract guarantees, said the team.
Increasing energy and nutritional efficiency while simultaneously reducing negative environmental impacts of pork production requires the adoption of precision nutrition practices in global pork production systems, believe the researchers.
Precision swine nutrition can only be achieved by using more accurate and comprehensive methods and measures to determine the true nutri-physiological value of feed ingredients used in swine diets, they added.
Combining net energy and digestible nutrient prediction equations derived from meta-analyses of large and robust data sets with NIRS determinations of total nutrient content of feed ingredients may be the most practical and accurate approach for dynamic estimation of nutrient loading values for feed formulation, they said.
So while promoting the use of the net energy system, SID AA content, and STTD phosphorus content measures for evaluating feed ingredients and formulating swine diets, they said additional measures should be considered in feed ingredient databases, including: (1) water activity; (2) solubility, fermentability, viscosity, and prebiotic effects of dietary fiber; (3) lipid and protein oxidation measures; and (4) estimates of true bioavailability of amino acids, vitamins, and minerals.
Furthermore, they see the assessment of the digestion kinetics of various dietary components - starch, dietary fiber, protein - as a promising new approach that allows the matching of the various rates and quantities of nutrients digested in mixtures of diverse feed ingredients to optimize nutri-physiological responses in swine.
Leveraging functional properties of feed ingredients
In terms of the rationale for carrying out the study now, Shurson told FeedNavigator: "We need to expand our thinking to involve strategies to reduce carbon footprint in pork production and exploit the functional properties of feed ingredients to improve swine health. Our ability to reduce the carbon footprint and environmental impact of food animal production is highly dependent on our ability to improve caloric and nutritional efficiency of the diets and feeding programs we use."
The study, he said, is about reviewing the significant limitations of using some traditional measurements, such as crude protein, which is woefully inadequate for optimizing pig performance, and nitrogen utilization efficiency, while also introducing emerging nutritional efficiency approaches, such as classifying ingredients based on digestion kinetics of starch, protein, and fiber to improve the synchronization of energy and nutrient utilization for swine.
"For many nutritionists, we often ignore, are unaware, or forget the principles and meaning of the routine analytical measures we use to assess feed ingredients and diets relative to predicting pig performance responses. A good example is the frequent generalization that dietary fiber is a generic indigestible component of swine diets, when we know it is actually very complex and is comprised of various types of carbohydrates that vary in their physicochemical properties and functions.
"We also need to understand and minimize the adverse effects of antinutritional components and take advantage of the functional benefits provided by many feed ingredients rather than focusing mainly on finding "silver bullet" alternatives to growth promoting antibiotics, which has dominated swine nutrition topics in recent years."
Zero carbon pig
We asked Dr Shurson if he would agree that there is still a healthy amount of skepticism in the industry about whether a precision swine nutrition approach can work in practice:
"There are certainly skeptics of the practicality and widespread adoption of precision livestock farming in many countries, but the increasing attention and efforts being devoted to improved environmental sustainability of food production, including pork production, is beginning to cause industry leaders to implement precision swine nutrition diet formulation and feeding program approaches.
"Some large pork production integrators have goals of carbon neutral pork production or producing a 'zero carbon' pig. Accomplishing this goal requires using precision swine nutrition practices and measures that matter."
Is there a broader use now of the digestion kinetics method when evaluating feed ingredients? "This concept is a point of high interest and discussion among some swine nutrition researchers but has minimal application. I think classifying feed ingredients based on digestion kinetics of various substrate components offers some interesting possibilities for enhancing caloric and nutritional efficiency as well as the gut health of pigs."
And how developed is the industry’s understanding of how circadian rhythms affect feeding behavior and the gastrointestinal microbiome of pigs? "This is another interesting and emerging area in nutritional sciences that is poorly understood at this point."
Source: Animals 2021
Title: Measures Matter—Determining the True Nutri-Physiological Value of Feed Ingredients for Swine.
Authors: Shurson, G.C.; Hung, Y.-T.; Jang, J.C.; Urriola, P.E.