Pelleting has the ability to improve feed efficiency (FE) and growth response of broilers, but it does not increase ME per unit of feed. The positive effect of pelleting on FE is due partly to a marked increase in feed intake and the reduction in energy spent on feed ingestion. Thus, pelleting improves the productive energy content of the feed. There are reports which confirm that pelleting contributes to 187 kcal of ME/kg of diet at 100% pellets (no fines) and this value decreases with the increase in proportions of fines to pellets, but still contributing 76 kcal of ME/kg of feed at 20% pellets. Other reported a contribution of 151 kcal of ME/kg of diet from pellets compared with mash diets. Few other reports also showed that broiler fed with pellets had lower heat increment and used more of the feed energy for productive purpose than those fed with mash. Based on these observations and findings, it is very reasonable to consider any feeding strategy that may decrease the time and energy spent on ingestion that will result in higher productive energy and, thus, better growth response from birds. Therefore, increasing the pellet size, as the birds grow older may offer an opportunity to reduce the bird’s energy expenditure for feed consumption and to improve FE. The most sensitive part of a pellet is the surface of the break resulting from cutting the pelleted feed into cylindrical pieces.
The number of these sensitive breaks depends on the pellet length, with short pellets yielding a higher number per mass than longer pellets, which results a greater possibility of abrasion and fines. Many researchers have already reported a strong linear relationship between pellet length and durability, regardless of grain type and die hole diameter, increasing the pellet length improve pellet integrity. Therefore, pellet length, though not usually considered, can have a significant effect on pellet quality.
Birds select feed particles in accordance with the size of their beak and oral cavity, which increase with the age. The preferred feed particle size increases, as the birds grow older. This can provide an opportunity to improve growth response if the most favorable pellet size for different age periods of the birds is identified. Though it is evident that broilers show better growth response when offered pelleted diets as opposed to mash diets, research is limited on the appropriate pellet size, especially pellet length, required by broilers.
Taking the reference from above tabulated findings published in The Journal of Applied Poultry Research, 2013, it is found that increasing pellet length (PL) from 3 mm to 5 and 7 mm can significantly improve PDI and pellet hardness. Although improvements were observed in both 5 and 7 mm pellets, a marked increase was associated with increasing the pellet length from 3 to 5 mm, which improved PDI and pellet hardness by 72.5 and 127.5% respectively. Corresponding improvements, when the pellet length was increased from 5 to 7 mm, were much lower (4.9 and 36.3%, respectively). These findings are also compatible with our findings at Delst Global with different clients which confirm that altering the pellet length from 3 to 6 mm, irrespective of diet composition and pellet diameter, increased the PDI and pellet hardness. Although, increasing pellet length improves PDI and pellet hardness yet before going for any such change, age of the birds must be considered as young broilers (714 d of age) show a preference for shorter pellets (3 mm) compared with longer pellets (5 mm). As discussed previously, there is a linear relationship between pellet length and durability of the pellet. Increasing the pellet length (PL) decreases the formation of fines simply by reducing the number of sensitive breaks per mass of pellet. As a result of increased pellet hardness in longer pellets, resistance to pellet breakdown due to pressure in bulk bins will also increase. Increasing the pellet length might be viewed as a possible manipulation to improve pellet quality; a strategy which can be more favorable in situations like Indian subcontinent where pellets undergo significant pneumatic and mechanical handling stresses from the time they are manufactured to the time they reach the feeders. As suggested before, I would like to reiterate here once again that, in pelleted diets, the percentage of intact pellets at the feeder should be considered as the final pellet quality and not the percentage of intact pellets at the feed mill