By Mark Knauer, North Carolina State University Assistant Professor and Extension Swine Specialist, and Eric van Heugten, North Carolina State University Professor and Extension Swine Specialist
Pelleting is a technology that is widely used in southeastern U.S. feed mills and gaining popularity in the Midwest as it offers economic, physical and nutritional benefits. Physical benefits of pelleting include improved ease of handling, reduced ingredient segregation, less feed wastage and increased bulk density (Behnke). Nutritional benefits of pelleting, as measured through feeding trials, are increased growth rate and increased nutrient utilization, resulting in improved feed efficiency. Pelleting research has tended to focus mainly on the benefits of pelleted diets in comparison to mash. Yet, limited research has evaluated the importance of pellet quality on finishing pig performance.
How is pellet quality measured? Pellet quality is commonly quantified by either the percentage of fines in the diet or by pellet durability index. More commonly used by scientists, pellet durability index is a standardized way to evaluate pellet quality. In short, pellet durability index is determined by placing 500 grams of pellets in a tumbling box, set at a standard speed, for 10 minutes. The remaining pellets are then screened, weighed and the ratio of remaining pellets to initial pellets is determined.
Does pellet quality impact the feed conversion of finishing pigs? Pacheco Dominguez (2014) reported the impact of feeding 25 versus 0% pellet fines on 760 finishing pigs. The author found feed efficiency was identical for both levels of pellet fines (2.64 versus 2.64). In agreement, Langdon (2015) found no impact of pellet fines (60, 45, 30, 15 or 0%) on the feed conversion of 180 pigs in late finishing. In contrast, Schell and van Heugten (1998) showed feed efficiency improved from 2.10 to 2.01 as the level of pellet fines decreased from 37% to 3% in grower pigs. In finishing pigs, Stark (1994) reported feed conversion improved from 2.82 to 2.65 as percent pellet fines decreased from 60% to 0%. Also in finishing pigs, Nemechek et al. (2013) reported feed efficiency for pigs fed 50% and 0% fines was 2.67 and 2.55, respectively. Perhaps differences between studies can be explained by whether the investigators adjusted feeders or not. In the study by Pacheco Dominguez (2014) feeders were adjusted on a regular basis in comparison to Stark (1994) where feeders were kept at a constant gap opening. This suggests that the impact of poor pellet quality on feed efficiency can be mitigated by proper feeder management. This is supported by Nemechek et al. (2013) who reported pigs fed 50% fines had improved feed conversion when feeders were adjusted to a ½-inch versus one-inch feeder opening (2.67 versus 2.82).
Does pellet quality impact the growth rate of finishing pigs? Studies have reported a greater level of pellet fines slightly decreases growth rate (Langdon, 2015) or has no impact on growth rate (Stark, 1994; Nemechek et al., 2013; Pacheco Dominguez, 2014; Langdon, 2015). These results suggest pellet quality generally has little or no impact on average daily gain. Yet pellet quality may influence the rate at which pigs eat. Langdon (2015) reported a tendency for greater pellet quality to be associated with less time spent eating. In agreement, Laitat et al. (2004) found pigs are able to consume pellets faster than mash feed. Hence lower pellet quality may increase feeder space requirements relative to pigs fed high-quality pellets.
— Without proper feeder management, poor or inconsistent pellet quality can impair finishing pig feed conversion.
— Pellet quality generally has little influence on finishing pig growth rate yet poor pellet quality may slightly increase feeder space requirements.
We would like to thank the National Pork Board and the North Carolina Pork Council for support of our pellet quality research.
Behnke, K. C. Factors influencing pellet quality.
Laitat, M., M. Vandenheede, A. Désiron, B. Canart, and B. Nicks. 2004. Influence of diet form (pellets or meal) on the optimal number of weaned pigs per feeding space. J. Swine Health Prod. 12(6):288-295.
Langdon, J. M. 2015. The Genetics of Pig Feeding Behavior. M.S. Thesis, North Carolina State University.
Nemechek, J., M. Tokach, E. Frugé, E. Hansen, S. Dritz, R. Goodband, J. DeRouchey, and J.Nelssen. 2013. Effects of pellet quality and feeder adjustment on growth performance of finishing pigs. J. Anim. Sci. 91(Suppl. 2):69.
Pacheco Dominguez, W. 2014. Effect of Particle Size and inclusion level of DDGS, and pellet quality on nutrient digestibility, gastrointestinal development, and live performance of broilers and swine. Ph.D. Dissertation.
Schell, T.C. and E. van Heugten. 1998. The effect of pellet quality on growth performance of grower pigs. J. Anim. Sci. 76(Suppl. 1):185.
Stark, C.R. 1994. Pellet quality I. Pellet quality and its effects on swine performance. Ph.D. Dissertation, Kansas State University, Manhattan.