Pellet quality and its effects on poultry performance

Joe Moritz - Professor and State Extension Specialist - Feed Manufacture and Poultry Science - West Virginia University

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Pellet quality provided to meat birds throughout the industry is highly variable. Feeding birds pellets of poor quality can in part be attributed to an emphasis on pellet mill throughput to generate adequate feed volume. However, perhaps a more compelling reason that feeding poor quality pellets is permitted is the lack of understanding associated with the relationship between pellet quality, bird performance, and economic impact. These data conclude that feeding high quality pellets provide performance advantages in modern meat bird genotypes; however, benefits are dependent upon manufacturing techniques having a minimal impact on decreasing nutrient availability. One technique that can be implemented to improve pellet quality without detriment to nutrient availability is the use of ingredients in feed formulation that have pellet binding properties. Algae biomass represents a potential feed ingredient that has pellet binding properties. In addition, recent research has demonstrated that a Spirulina algae biomass contains 2,839 kcal/kg, 1.07, 2.10, and 1.97, digestible methionine, lysine, and threonine respectively and can be successfully utilized in broiler starter diets at a 16% inclusion.

Reasons for lack of understanding
Over the years, little progress has been made towards convincing the meat bird industry that feeding high quality pellets has justifiable advantages for bird performance and overall economics. This lack of progress may be attributed to conflicting results in commercial practice and past literature, variables per se and confounding variables that are not accounted for in commercial practice and past literature, and the fact that few companies and universities conduct feed manufacture and feeding research. The following are scenarios that demonstrate how confounding variables can lead to conflicting results:

– If thermally gentle manufacturing techniques are utilized (low conditioning temperature, thin pellet die, fast production rate, high pre-pellet (mixer-added) fat application, etc.) that create pellets of poor quality but maintain high nutrient availability then performance may be at an acceptable level and pellet quality could be viewed as not having importance;

– If thermally harsh manufacturing techniques are utilized (high conditioning temperature, thick pellet die, slow production rate, high post-pellet fat application, etc.) that create pellets of high quality but decrease nutrient availability then expected performance benefits may not be observed and pellet quality could be viewed as not having importance;

  • If pellets of high quality are manufactured using techniques that do not decrease nutrient availability then performance improvements may be attained and pellet quality could be viewed as having importance.

Feed form independent of nutrient availability
A more accurate assessment of feed form effects can be attained if all feed-to-be-used in a research study is made using the same manufacture techniques so that effects on nutrient availability are consistent, then a portion of that feed is ground and utilized as a treatment.

Nutrient availability independent of feed for
A more accurate assessment of nutrient availability effects can be attained if all feed-to-be-used in a research study is made using similar lots of ingredients, different manufacture techniques, and all feed being ground prior to feeding to eliminate feed form effects.

Feed form, ingredient, and nutrient segregation
The effects of pellet quality on ingredient and nutrient segregation are seldom accounted for in past research. Pellets and fines segregate within feed bins as well as during their conveyance throughout a house. If ingredients and nutrients vary between pellets and fines then birds within different locations of the house will consume different nutrient concentrations. This problem would likely be exacerbated when poor quality pellets are produced and liquid ingredients are applied post-pelleting. Collaborative research currently being conducted at West Virginia and Mississippi State Universities will attempt to better define segregation conditions and understand subsequent feeding effects. One replicate from our data set is included below as an example. In this example, phytase was applied post pelleting and samples were obtained from the feed mill and tracked to a commercial house.

Algae as a feed ingredient with pellet binding properties
Pellet binders have been shown to affect nutritional profile, feed manufacture, and nutrient availability in addition to pellet quality. Algae biomass, produced from a Spirulina source has demonstrated multiple benefits for use in feeding broiler chickens. Algae biomass, corn, and a 50% mix of the two were precision fed to intact and cecectomized Single Comb White Leghorn Roosters with 6 replications per treatment to determine TMEn and TAAD, respectively. All treatments differed for TMEn and TAAD (P<0.0001). Algae biomass metabolizable energy was determined to be 2,839 kcal/kg and the digestible methionine, cysteine, lysine, and threonine coefficients were determined to be 1.07, 0.42, 2.10, and 1.97, respectively. Algae biomass was also analyzed for total calcium and phosphorus and these values were adjusted to 90 and 33% availability, respectively. Commercial levels of nutrients for Cobb 500 broilers were used to formulate a diets to test the practicality of algae biomass as a feed ingredient. Based on metabolizable energy, digestible amino acids, and calculated mineral availabilities a starter diet containing up to 21% algae biomass was formulated. A diet containing 0% algae biomass was also formulated. Both diets were pelleted at 180°F, ground, and mixed at different ratios to create diets containing 6, 11, 16% algae biomass, as well as a diet containing 0% algae biomass with a green food coloring. The diet containing 21% algae biomass had a pellet durability index of 98%. The diet containing 0% algae biomass had a pellet durability index of 73%. Diets were randomly assigned to pens containing 10 broiler chicks and were fed from d1-21. On day 21, birds were euthanized and contents of the lower ileum were collected and analyzed for amino acid and titanium content. Diets containing 6, 11, and 16% algae biomass were statistically similar to the 0% algae biomass diet for ending bird weight, feed intake, live weight gain, and feed conversion ratio. The 21% algae biomass inclusion decreased performance, possibly due to nutrient binding properties that were similar to pellet binding properties. Ileal digestibility supported true amino acid digestibility data and performance data, demonstrating the most value in formulations with 16% algae biomass.

Conclusion
Feeding high quality pellets provides performance advantages in modern meat bird genotypes; however, benefits are dependent upon manufacturing techniques having a minimal impact on decreasing nutrient availability. Thus far, research has indicated that manufacturing technique can decrease amino acid digestibility, enzyme efficacy, and the protein to energy ratio. High quality pellets also have potential to provide performance and flock uniformity benefits by decreasing ingredient and nutrient segregation. Pellet binders that additionally enhance nutrient availability may provide a strategy to maximize economic return of feeding high quality pellets.