Feed efficiency is essential in pork production optimizing growth and maximizing nutrient use. 

This project validated the use of thermal efficiency index (TEI) for evaluating feed efficiency in growing pigs. This study investigated the relationship between thermal efficiency and stress resilience. In a 2 x 2 design, weaner pigs were assessed for TEI, with high and low TEI animals selected; half of each group received a commercial supplement in water (DSS, designed to reduce stress) for 24h before and after stressful events, and half were treated as control. Pigs were challenged with a controlled handling and mixing stressor at 12 and 16 weeks respectively. Infrared temperature was evaluated before and after each stressor with additional salivary cortisol and thermal imaging measurements in the second replicate. TEI shows a consistent correlation with average daily gain, which indicates a valid metric for measuring pigs’ growth. Use of DSS in water significantly reduced lesion scores at mixing compared to the control and produced a greater change in TEI in response to handling and mixing stressors.  

Inefficient pig waste more energy

Feed efficiency is variable with ‘inefficient’ animals wasting more energy by giving off more heat than efficient animals, and/or absorbing less energy from feed and releasing unused nutrients to the environment. The thermal output of animals is thus a potentially useful measure for estimating feed efficiency. Infrared thermography can assess thermal output in real time and shows many other technical and practical advantages. The procedure is non-invasive and can be used to rank an animals’ efficiency in approximately 20 seconds. The technology has also been patented, beta site tested, and is now entering use in commercial facilities. Further work is needed to validate TEI as a tool in swine production, including for example knowledge on relationships between TEI and stress resilience, the effects of different diet formulations on TEI, heritability of TEI, as well as relationships with susceptibility to heat stress and pig temperament. The application of thermal profiles will be of particular benefit to genetic companies. By facilitating the early selection of pigs on the basis of efficiency, faster genetic progress can be achieved.

Because TEI can be measured in early life, the application of infrared technology and thermal profiles could also benefit pork producers. If young pigs can be sorted based on feed efficiency at the weaner or grower stage, diets can be prepared based on the different needs of each group. With thermal classification, each group of pigs would be provided a diet nutritionally tailored to better meet their needs, resulting in improved efficiency.

What we found

As the nature of TEI calculation considers body weight, we were not able to perfectly balance the body weight at entry. At weaning age, the greater feed efficiency of LOW animals resulted in higher body weights compared to HIGH animals. The average baseline weight for LOW pigs was almost 5kg heavier than the average for HIGH pigs (20.28 ±1.82 kg vs 15.61 ±1.43 kg, P < 0.001). Average weight at trial entry did not differ between dietary treatment groups. LOW pigs tended to have a higher ADG from 8-12 weeks. During Finisher 1, LOW pigs consumed more feed and had greater ADG with no difference in G:F. During Finisher 2, there was no difference in ADFI, ADG or G:F between TEI categories. The overall ADG throughout the grower-finisher stage was greater for LOW than HIGH pigs. LOW pigs had greater slaughter weight, and fat (mm). There was no effect of TEI on loin depth. 

During handling at 12 weeks, DSS tended to affect the change of TEI (∆TEI), with pigs given DSS showing greater change (Figure 1). In the mixing stressor at 16 weeks test, DSS pigs showed a greater ∆TEI than CTR pigs, with no effect of TEI category (Figure 2). Thermal efficiency and DSS treatment did not affect behaviour during handling. DSS treatment affected lesion scores at mixing: CTR animals received more head lesions and tended to have more mid-body lesions compared to DSS. TEI category tended to influence hind-end lesions; scores of HIGH pigs showed less change than LOW.

In terms of the relationship between thermal efficiency index and bodyweight, a linear correlation was detected. Initial TEI and bodyweight were negatively correlated, similarly at week 12, which means that pigs with lower TEI were consistently heavier. Interestingly, in week 12 after the handling stress, the correlation decreased, which suggests that pigs’ body temperature was indeed disrupted by the handling stress process. Similar results were found at week 16 before the mixing stress and after.

Implications

The findings based on thermal efficiency alone exhibit that TEI can be used to identify pigs with better performance in terms of weight gain and carcass yield. Based on data from the beginning of the trial, at week 12, and at slaughter, there was a negative correlation between TEI and bodyweight, with LOW pigs being heavier at each point. Both handling and mixing stress decreased the extent of this negative correlation, exhibiting the physiological influence of stress. 

This project is supported by the Saskatchewan Agriculture Development Fund

Ask a producer if they’d rather save money or save the planet, and the answer is simple: Yes.

That’s why researchers embarked on a project to increase nutrient utilization of feedstuffs consumed by growing-finishing pigs, thereby reducing feed costs and the industry’s environmental footprint. Both are noble goals, and both are top of mind for the pork sector these days. With feed still responsible for 65 to 70 per cent of production expense, it continues to gobble up producer profits. This is especially true for growing-finishing pigs, as they account for about 80 per cent of all feed consumed.

Just as important as cutting costs these days is minimizing impact on the environment. Worldwide, the demand for animal protein is expected to reach over 400 million tonnes per year by 2050, a jump of 70 per cent from today driven by a growing world population.

Against that backdrop, it is vital that pig production be sustainable, and that means keeping it green.

Addressing GHG…ASAP

As with other food animal production, the pork industry is continuously striving for feed conversion efficiency while reducing its environmental footprint by doing more with less. Despite continued progress, production systems do face challenges like greenhouse gas emissions (GHG), foul smelling odors from swine manure and the management of large volumes of pig manure slurry.

When swine manure is spread on the farm, it may lead to soil accumulation of minerals such as phosphorus (P), copper (Cu) and zinc (Zn). Heavy metal contamination of soil with Cu and Zn can pose antimicrobial-resistance risks and hazards to humans and the ecosystem through various means: direct ingestion or contact with contaminated soil, drinking of contaminated ground water with antimicrobial resistant bacteria, and a reduction in food quality and usable land for agricultural production.

When the manure hits the fan

The impact of swine farms on the environment has prompted new legislation in some countries that limits the use of animal manure or the expansion or localization of pig operations. Feeling the urgency to make a difference, scientists focused on one of the main causes of manure issues that may harm the environment: the limited capacity of pig guts to properly digest dietary fiber, leading to poor utilization of that fiber in commercial swine diets. 

In part, this is due to the use of ingredients that are high in low-cost agricultural by-products. Those by-products include wheat-shorts (leftover particles of bran, germ and flour produced during the milling process), wheat brans and oil meals such as canola meal and soybean meal.

While commercial fiber enzyme products have been around for years, they are limited in their stability and effectiveness in enhancing fiber digestion as part of swine feeding. They were originally developed for biofuel and light industrial applications, but were not custom-developed and designed for the livestock feed sector. Seeking a better alternative, researchers have been developing novel fiber enzymes to help resolve environmental footprint issues caused largely by the poor efficiency of natural dietary fiber.

A breakdown breakthrough

As a reward for their efforts, scientists discovered a small, unique and multi-functional enzyme that is very rare in the natural environment. To accomplish this, they focused on designing a new generation of "custom-made" fibre enzymes specifically for livestock feeding applications. As well, they thoroughly investigated the stability of their newly developed enzymes in the pig gut environment to ensure their viability in the field or barn.

The enzyme breaks down dietary fiber into small end-products, rendering them easier to digest for pigs and their fussy guts. Referred to as "mono-modular, multi-functional and processive endocellulases", these enzymes may lack a catchy name, but their potential is catching interest from the pork sector. 

Because the enzymes are customized and optimized for pig feed applications, they will improve key aspects of pig growth performance such as feed conversion, thereby enhancing profit margins for producers. The enzymes will also support more efficient digestive utilization of dietary nutrients such as fibre and protein that contain carbon (C) and nitrogen (N). By doing so, they will reduce the production and emissions of the major greenhouse gases - methane (CH4) and nitrous oxide (N2O) - that emerge from liquid swine manure slurry.

Once commercialized, these enzymes have the potential to dramatically improve feed conversion efficiency, profit margins and the environmental impact of pork production. Researchers are excited about the discovery’s potential to help producers continue to achieve better outcomes while reducing costs and environmental impact.

Because of its highly innovative nature, multiple sources of support and partners have been involved in this project for the past decade, working primarily at a lab at the University of Guelph (U of G) in Ontario. Contributors to the study include Mr. Laurence Cheng, a graduate student, and Dr. Weijun Wang, adjunct professor, both in the Department of Animal Biosciences at the U of G. 

The team’s work has also been supported by research programs from the Natural Science and Engineering Research Council of Canada (NSERC), Agriculture and Agri-Food Canada (AAFC), the Swine Innovation Porc (SIP) Swine Cluster Program, and the Ontario Ministry of Agriculture, Food & Rural Affairs (OMAFRA).

 Study plan

As a next step, the project team is seeking industrial partners to sponsor further study of this fiber enzyme by way of in vivo research (a specific type of experimentation that involves living pigs). In order to make this enzyme available to producers and industry in the future, scientists must study its effectiveness and functionality in pigs, as well as its physiological properties. By doing so, they hope to gather sufficient data to support governmental approval of the enzymes for commercial applications.

Innovation and discovery are well recognized in the pork industry as critical to unlock profitability, competitiveness and sustainability. The breakthrough on this project underlines the need for science and its commitment to continuous improvement. Though image is not everything, success in reducing costs while protecting the environment should impress both producers and consumers, keeping Canadian pork producers ahead of the curve.