Is the protein digestibility overestimated in piglet feed formulation?

Article by Simone Husballe Rasmussen, Trial Coordinator at HAMLET PROTEIN

Formulating feed for piglets is a challenging task, involving numerous considerations to make sure that the piglets eat the feed and grow efficiently. Nutrient digestibility – and especially protein digestibility – is a primary concern as most published values for ingredient digestibility have been determined in heavier growing or finishing pigs. Current formulation practices use these digestibility values when formulating diets for piglets, which, consequently leads to overestimated digestibility of raw materials when used in smaller animals.

A meta-analysis was conducted by HAMLET PROTEIN in collaboration with the University of Illinois to evaluate the age-related differences in nutrient digestibility. Standardized ileal digestibility (SID) data published in 1998 to 2013 were used, and covered soy-based ingredients for piglet starter feed.

Pig weight does have an impact

The meta-analysis also investigated the SID of CP in animals of different weight and results obtained for CP in SBM (48%) are displayed in table 2. Piglets below 20kg at the start of the experimental period had a significantly lower SID than pigs above 20kg, substantiating that published values for ingredient digestibility based on measurements in growing or finishing pigs are not applicable to pigs that weigh less than 20kg. Further, if those values are used to formulate diets for piglets, the amount of amino acids that is absorbed by the piglets is less than expected.

Table 2. Effect of initial body weight on SID (%) of CP in SBM (48%). Piglets below 20kg digest CP less efficient than piglets above 20kg.

Feed formulation based on age specific matrix values

Based on the meta-analysis, the most correct way to formulate feed for piglets would be to use a set of nutrient specifications that has been specifically developed for young pigs. Consequently, the same exercise should be done for all other raw materials, resulting in feed tables that contain two or more age specific matrix values, reflecting the physiological development of pigs. This requires further research. For now, the optimal strategy is to use already published values, which is based on growing and finishing pigs while keeping in mind that the amount of nutrients available to the newly weaned piglet is overestimated.

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